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WSL2-Linux-Kernel
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WSL2-Linux-Kernel/drivers/i2c/i2c-core-base.c

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66 KiB
C
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/*
* Linux I2C core
*
* Copyright (C) 1995-99 Simon G. Vogl
* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>
* Mux support by Rodolfo Giometti <giometti@enneenne.com> and
* Michael Lawnick <michael.lawnick.ext@nsn.com>
*
* Copyright (C) 2013-2017 Wolfram Sang <wsa@the-dreams.de>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
*/
#define pr_fmt(fmt) "i2c-core: " fmt
#include <dt-bindings/i2c/i2c.h>
#include <linux/acpi.h>
#include <linux/clk/clk-conf.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/i2c-smbus.h>
#include <linux/idr.h>
#include <linux/init.h>
#include <linux/irqflags.h>
#include <linux/jump_label.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of_device.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/pm_domain.h>
#include <linux/pm_runtime.h>
#include <linux/pm_wakeirq.h>
#include <linux/property.h>
#include <linux/rwsem.h>
#include <linux/slab.h>
#include "i2c-core.h"
#define CREATE_TRACE_POINTS
#include <trace/events/i2c.h>
#define I2C_ADDR_OFFSET_TEN_BIT 0xa000
#define I2C_ADDR_OFFSET_SLAVE 0x1000
#define I2C_ADDR_7BITS_MAX 0x77
#define I2C_ADDR_7BITS_COUNT (I2C_ADDR_7BITS_MAX + 1)
#define I2C_ADDR_DEVICE_ID 0x7c
/*
* core_lock protects i2c_adapter_idr, and guarantees that device detection,
* deletion of detected devices are serialized
*/
static DEFINE_MUTEX(core_lock);
static DEFINE_IDR(i2c_adapter_idr);
static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
static DEFINE_STATIC_KEY_FALSE(i2c_trace_msg_key);
static bool is_registered;
int i2c_transfer_trace_reg(void)
{
static_branch_inc(&i2c_trace_msg_key);
return 0;
}
void i2c_transfer_trace_unreg(void)
{
static_branch_dec(&i2c_trace_msg_key);
}
const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
const struct i2c_client *client)
{
if (!(id && client))
return NULL;
while (id->name[0]) {
if (strcmp(client->name, id->name) == 0)
return id;
id++;
}
return NULL;
}
EXPORT_SYMBOL_GPL(i2c_match_id);
static int i2c_device_match(struct device *dev, struct device_driver *drv)
{
struct i2c_client *client = i2c_verify_client(dev);
struct i2c_driver *driver;
/* Attempt an OF style match */
if (i2c_of_match_device(drv->of_match_table, client))
return 1;
/* Then ACPI style match */
if (acpi_driver_match_device(dev, drv))
return 1;
driver = to_i2c_driver(drv);
/* Finally an I2C match */
if (i2c_match_id(driver->id_table, client))
return 1;
return 0;
}
static int i2c_device_uevent(struct device *dev, struct kobj_uevent_env *env)
{
struct i2c_client *client = to_i2c_client(dev);
int rc;
rc = of_device_uevent_modalias(dev, env);
if (rc != -ENODEV)
return rc;
rc = acpi_device_uevent_modalias(dev, env);
if (rc != -ENODEV)
return rc;
return add_uevent_var(env, "MODALIAS=%s%s", I2C_MODULE_PREFIX, client->name);
}
/* i2c bus recovery routines */
static int get_scl_gpio_value(struct i2c_adapter *adap)
{
return gpiod_get_value_cansleep(adap->bus_recovery_info->scl_gpiod);
}
static void set_scl_gpio_value(struct i2c_adapter *adap, int val)
{
gpiod_set_value_cansleep(adap->bus_recovery_info->scl_gpiod, val);
}
static int get_sda_gpio_value(struct i2c_adapter *adap)
{
return gpiod_get_value_cansleep(adap->bus_recovery_info->sda_gpiod);
}
static void set_sda_gpio_value(struct i2c_adapter *adap, int val)
{
gpiod_set_value_cansleep(adap->bus_recovery_info->sda_gpiod, val);
}
static int i2c_generic_bus_free(struct i2c_adapter *adap)
{
struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
int ret = -EOPNOTSUPP;
if (bri->get_bus_free)
ret = bri->get_bus_free(adap);
else if (bri->get_sda)
ret = bri->get_sda(adap);
if (ret < 0)
return ret;
return ret ? 0 : -EBUSY;
}
/*
* We are generating clock pulses. ndelay() determines durating of clk pulses.
* We will generate clock with rate 100 KHz and so duration of both clock levels
* is: delay in ns = (10^6 / 100) / 2
*/
#define RECOVERY_NDELAY 5000
#define RECOVERY_CLK_CNT 9
int i2c_generic_scl_recovery(struct i2c_adapter *adap)
{
struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
int i = 0, scl = 1, ret = 0;
if (bri->prepare_recovery)
bri->prepare_recovery(adap);
/*
* If we can set SDA, we will always create a STOP to ensure additional
* pulses will do no harm. This is achieved by letting SDA follow SCL
* half a cycle later. Check the 'incomplete_write_byte' fault injector
* for details.
*/
bri->set_scl(adap, scl);
ndelay(RECOVERY_NDELAY / 2);
if (bri->set_sda)
bri->set_sda(adap, scl);
ndelay(RECOVERY_NDELAY / 2);
/*
* By this time SCL is high, as we need to give 9 falling-rising edges
*/
while (i++ < RECOVERY_CLK_CNT * 2) {
if (scl) {
/* SCL shouldn't be low here */
if (!bri->get_scl(adap)) {
dev_err(&adap->dev,
"SCL is stuck low, exit recovery\n");
ret = -EBUSY;
break;
}
}
scl = !scl;
bri->set_scl(adap, scl);
/* Creating STOP again, see above */
ndelay(RECOVERY_NDELAY / 2);
if (bri->set_sda)
bri->set_sda(adap, scl);
ndelay(RECOVERY_NDELAY / 2);
if (scl) {
ret = i2c_generic_bus_free(adap);
if (ret == 0)
break;
}
}
/* If we can't check bus status, assume recovery worked */
if (ret == -EOPNOTSUPP)
ret = 0;
if (bri->unprepare_recovery)
bri->unprepare_recovery(adap);
return ret;
}
EXPORT_SYMBOL_GPL(i2c_generic_scl_recovery);
int i2c_recover_bus(struct i2c_adapter *adap)
{
if (!adap->bus_recovery_info)
return -EOPNOTSUPP;
dev_dbg(&adap->dev, "Trying i2c bus recovery\n");
return adap->bus_recovery_info->recover_bus(adap);
}
EXPORT_SYMBOL_GPL(i2c_recover_bus);
static void i2c_init_recovery(struct i2c_adapter *adap)
{
struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
char *err_str;
if (!bri)
return;
if (!bri->recover_bus) {
err_str = "no recover_bus() found";
goto err;
}
if (bri->scl_gpiod && bri->recover_bus == i2c_generic_scl_recovery) {
bri->get_scl = get_scl_gpio_value;
bri->set_scl = set_scl_gpio_value;
if (bri->sda_gpiod) {
bri->get_sda = get_sda_gpio_value;
/* FIXME: add proper flag instead of '0' once available */
if (gpiod_get_direction(bri->sda_gpiod) == 0)
bri->set_sda = set_sda_gpio_value;
}
return;
}
if (bri->recover_bus == i2c_generic_scl_recovery) {
/* Generic SCL recovery */
if (!bri->set_scl || !bri->get_scl) {
err_str = "no {get|set}_scl() found";
goto err;
}
if (!bri->set_sda && !bri->get_sda) {
err_str = "either get_sda() or set_sda() needed";
goto err;
}
}
return;
err:
dev_err(&adap->dev, "Not using recovery: %s\n", err_str);
adap->bus_recovery_info = NULL;
}
static int i2c_smbus_host_notify_to_irq(const struct i2c_client *client)
{
struct i2c_adapter *adap = client->adapter;
unsigned int irq;
if (!adap->host_notify_domain)
return -ENXIO;
if (client->flags & I2C_CLIENT_TEN)
return -EINVAL;
irq = irq_create_mapping(adap->host_notify_domain, client->addr);
return irq > 0 ? irq : -ENXIO;
}
static int i2c_device_probe(struct device *dev)
{
struct i2c_client *client = i2c_verify_client(dev);
struct i2c_driver *driver;
int status;
if (!client)
return 0;
driver = to_i2c_driver(dev->driver);
if (!client->irq && !driver->disable_i2c_core_irq_mapping) {
int irq = -ENOENT;
if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
dev_dbg(dev, "Using Host Notify IRQ\n");
/* Keep adapter active when Host Notify is required */
pm_runtime_get_sync(&client->adapter->dev);
irq = i2c_smbus_host_notify_to_irq(client);
} else if (dev->of_node) {
irq = of_irq_get_byname(dev->of_node, "irq");
if (irq == -EINVAL || irq == -ENODATA)
irq = of_irq_get(dev->of_node, 0);
} else if (ACPI_COMPANION(dev)) {
irq = acpi_dev_gpio_irq_get(ACPI_COMPANION(dev), 0);
}
if (irq == -EPROBE_DEFER)
return irq;
if (irq < 0)
irq = 0;
client->irq = irq;
}
/*
* An I2C ID table is not mandatory, if and only if, a suitable OF
* or ACPI ID table is supplied for the probing device.
*/
if (!driver->id_table &&
!i2c_acpi_match_device(dev->driver->acpi_match_table, client) &&
!i2c_of_match_device(dev->driver->of_match_table, client))
return -ENODEV;
if (client->flags & I2C_CLIENT_WAKE) {
int wakeirq = -ENOENT;
if (dev->of_node) {
wakeirq = of_irq_get_byname(dev->of_node, "wakeup");
if (wakeirq == -EPROBE_DEFER)
return wakeirq;
}
device_init_wakeup(&client->dev, true);
if (wakeirq > 0 && wakeirq != client->irq)
status = dev_pm_set_dedicated_wake_irq(dev, wakeirq);
else if (client->irq > 0)
status = dev_pm_set_wake_irq(dev, client->irq);
else
status = 0;
if (status)
dev_warn(&client->dev, "failed to set up wakeup irq\n");
}
dev_dbg(dev, "probe\n");
status = of_clk_set_defaults(dev->of_node, false);
if (status < 0)
goto err_clear_wakeup_irq;
status = dev_pm_domain_attach(&client->dev, true);
if (status)
goto err_clear_wakeup_irq;
/*
* When there are no more users of probe(),
* rename probe_new to probe.
*/
if (driver->probe_new)
status = driver->probe_new(client);
else if (driver->probe)
status = driver->probe(client,
i2c_match_id(driver->id_table, client));
else
status = -EINVAL;
if (status)
goto err_detach_pm_domain;
return 0;
err_detach_pm_domain:
dev_pm_domain_detach(&client->dev, true);
err_clear_wakeup_irq:
dev_pm_clear_wake_irq(&client->dev);
device_init_wakeup(&client->dev, false);
return status;
}
static int i2c_device_remove(struct device *dev)
{
struct i2c_client *client = i2c_verify_client(dev);
struct i2c_driver *driver;
int status = 0;
if (!client || !dev->driver)
return 0;
driver = to_i2c_driver(dev->driver);
if (driver->remove) {
dev_dbg(dev, "remove\n");
status = driver->remove(client);
}
dev_pm_domain_detach(&client->dev, true);
dev_pm_clear_wake_irq(&client->dev);
device_init_wakeup(&client->dev, false);
client->irq = client->init_irq;
if (client->flags & I2C_CLIENT_HOST_NOTIFY)
pm_runtime_put(&client->adapter->dev);
return status;
}
static void i2c_device_shutdown(struct device *dev)
{
struct i2c_client *client = i2c_verify_client(dev);
struct i2c_driver *driver;
if (!client || !dev->driver)
return;
driver = to_i2c_driver(dev->driver);
if (driver->shutdown)
driver->shutdown(client);
}
static void i2c_client_dev_release(struct device *dev)
{
kfree(to_i2c_client(dev));
}
static ssize_t
show_name(struct device *dev, struct device_attribute *attr, char *buf)
{
return sprintf(buf, "%s\n", dev->type == &i2c_client_type ?
to_i2c_client(dev)->name : to_i2c_adapter(dev)->name);
}
static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
static ssize_t
show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
{
struct i2c_client *client = to_i2c_client(dev);
int len;
len = of_device_modalias(dev, buf, PAGE_SIZE);
if (len != -ENODEV)
return len;
len = acpi_device_modalias(dev, buf, PAGE_SIZE -1);
if (len != -ENODEV)
return len;
return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
}
static DEVICE_ATTR(modalias, S_IRUGO, show_modalias, NULL);
static struct attribute *i2c_dev_attrs[] = {
&dev_attr_name.attr,
/* modalias helps coldplug: modprobe $(cat .../modalias) */
&dev_attr_modalias.attr,
NULL
};
ATTRIBUTE_GROUPS(i2c_dev);
struct bus_type i2c_bus_type = {
.name = "i2c",
.match = i2c_device_match,
.probe = i2c_device_probe,
.remove = i2c_device_remove,
.shutdown = i2c_device_shutdown,
};
EXPORT_SYMBOL_GPL(i2c_bus_type);
struct device_type i2c_client_type = {
.groups = i2c_dev_groups,
.uevent = i2c_device_uevent,
.release = i2c_client_dev_release,
};
EXPORT_SYMBOL_GPL(i2c_client_type);
/**
* i2c_verify_client - return parameter as i2c_client, or NULL
* @dev: device, probably from some driver model iterator
*
* When traversing the driver model tree, perhaps using driver model
* iterators like @device_for_each_child(), you can't assume very much
* about the nodes you find. Use this function to avoid oopses caused
* by wrongly treating some non-I2C device as an i2c_client.
*/
struct i2c_client *i2c_verify_client(struct device *dev)
{
return (dev->type == &i2c_client_type)
? to_i2c_client(dev)
: NULL;
}
EXPORT_SYMBOL(i2c_verify_client);
/* Return a unique address which takes the flags of the client into account */
static unsigned short i2c_encode_flags_to_addr(struct i2c_client *client)
{
unsigned short addr = client->addr;
/* For some client flags, add an arbitrary offset to avoid collisions */
if (client->flags & I2C_CLIENT_TEN)
addr |= I2C_ADDR_OFFSET_TEN_BIT;
if (client->flags & I2C_CLIENT_SLAVE)
addr |= I2C_ADDR_OFFSET_SLAVE;
return addr;
}
/* This is a permissive address validity check, I2C address map constraints
* are purposely not enforced, except for the general call address. */
static int i2c_check_addr_validity(unsigned int addr, unsigned short flags)
{
if (flags & I2C_CLIENT_TEN) {
/* 10-bit address, all values are valid */
if (addr > 0x3ff)
return -EINVAL;
} else {
/* 7-bit address, reject the general call address */
if (addr == 0x00 || addr > 0x7f)
return -EINVAL;
}
return 0;
}
/* And this is a strict address validity check, used when probing. If a
* device uses a reserved address, then it shouldn't be probed. 7-bit
* addressing is assumed, 10-bit address devices are rare and should be
* explicitly enumerated. */
int i2c_check_7bit_addr_validity_strict(unsigned short addr)
{
/*
* Reserved addresses per I2C specification:
* 0x00 General call address / START byte
* 0x01 CBUS address
* 0x02 Reserved for different bus format
* 0x03 Reserved for future purposes
* 0x04-0x07 Hs-mode master code
* 0x78-0x7b 10-bit slave addressing
* 0x7c-0x7f Reserved for future purposes
*/
if (addr < 0x08 || addr > 0x77)
return -EINVAL;
return 0;
}
static int __i2c_check_addr_busy(struct device *dev, void *addrp)
{
struct i2c_client *client = i2c_verify_client(dev);
int addr = *(int *)addrp;
if (client && i2c_encode_flags_to_addr(client) == addr)
return -EBUSY;
return 0;
}
/* walk up mux tree */
static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
{
struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
int result;
result = device_for_each_child(&adapter->dev, &addr,
__i2c_check_addr_busy);
if (!result && parent)
result = i2c_check_mux_parents(parent, addr);
return result;
}
/* recurse down mux tree */
static int i2c_check_mux_children(struct device *dev, void *addrp)
{
int result;
if (dev->type == &i2c_adapter_type)
result = device_for_each_child(dev, addrp,
i2c_check_mux_children);
else
result = __i2c_check_addr_busy(dev, addrp);
return result;
}
static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
{
struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
int result = 0;
if (parent)
result = i2c_check_mux_parents(parent, addr);
if (!result)
result = device_for_each_child(&adapter->dev, &addr,
i2c_check_mux_children);
return result;
}
/**
* i2c_adapter_lock_bus - Get exclusive access to an I2C bus segment
* @adapter: Target I2C bus segment
* @flags: I2C_LOCK_ROOT_ADAPTER locks the root i2c adapter, I2C_LOCK_SEGMENT
* locks only this branch in the adapter tree
*/
static void i2c_adapter_lock_bus(struct i2c_adapter *adapter,
unsigned int flags)
{
rt_mutex_lock_nested(&adapter->bus_lock, i2c_adapter_depth(adapter));
}
/**
* i2c_adapter_trylock_bus - Try to get exclusive access to an I2C bus segment
* @adapter: Target I2C bus segment
* @flags: I2C_LOCK_ROOT_ADAPTER trylocks the root i2c adapter, I2C_LOCK_SEGMENT
* trylocks only this branch in the adapter tree
*/
static int i2c_adapter_trylock_bus(struct i2c_adapter *adapter,
unsigned int flags)
{
return rt_mutex_trylock(&adapter->bus_lock);
}
/**
* i2c_adapter_unlock_bus - Release exclusive access to an I2C bus segment
* @adapter: Target I2C bus segment
* @flags: I2C_LOCK_ROOT_ADAPTER unlocks the root i2c adapter, I2C_LOCK_SEGMENT
* unlocks only this branch in the adapter tree
*/
static void i2c_adapter_unlock_bus(struct i2c_adapter *adapter,
unsigned int flags)
{
rt_mutex_unlock(&adapter->bus_lock);
}
static void i2c_dev_set_name(struct i2c_adapter *adap,
struct i2c_client *client,
struct i2c_board_info const *info)
{
struct acpi_device *adev = ACPI_COMPANION(&client->dev);
if (info && info->dev_name) {
dev_set_name(&client->dev, "i2c-%s", info->dev_name);
return;
}
if (adev) {
dev_set_name(&client->dev, "i2c-%s", acpi_dev_name(adev));
return;
}
dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
i2c_encode_flags_to_addr(client));
}
static int i2c_dev_irq_from_resources(const struct resource *resources,
unsigned int num_resources)
{
struct irq_data *irqd;
int i;
for (i = 0; i < num_resources; i++) {
const struct resource *r = &resources[i];
if (resource_type(r) != IORESOURCE_IRQ)
continue;
if (r->flags & IORESOURCE_BITS) {
irqd = irq_get_irq_data(r->start);
if (!irqd)
break;
irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS);
}
return r->start;
}
return 0;
}
/**
* i2c_new_client_device - instantiate an i2c device
* @adap: the adapter managing the device
* @info: describes one I2C device; bus_num is ignored
* Context: can sleep
*
* Create an i2c device. Binding is handled through driver model
* probe()/remove() methods. A driver may be bound to this device when we
* return from this function, or any later moment (e.g. maybe hotplugging will
* load the driver module). This call is not appropriate for use by mainboard
* initialization logic, which usually runs during an arch_initcall() long
* before any i2c_adapter could exist.
*
* This returns the new i2c client, which may be saved for later use with
* i2c_unregister_device(); or an ERR_PTR to describe the error.
*/
static struct i2c_client *
i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
{
struct i2c_client *client;
int status;
client = kzalloc(sizeof *client, GFP_KERNEL);
if (!client)
return ERR_PTR(-ENOMEM);
client->adapter = adap;
client->dev.platform_data = info->platform_data;
client->flags = info->flags;
client->addr = info->addr;
client->init_irq = info->irq;
if (!client->init_irq)
client->init_irq = i2c_dev_irq_from_resources(info->resources,
info->num_resources);
client->irq = client->init_irq;
strlcpy(client->name, info->type, sizeof(client->name));
status = i2c_check_addr_validity(client->addr, client->flags);
if (status) {
dev_err(&adap->dev, "Invalid %d-bit I2C address 0x%02hx\n",
client->flags & I2C_CLIENT_TEN ? 10 : 7, client->addr);
goto out_err_silent;
}
/* Check for address business */
status = i2c_check_addr_busy(adap, i2c_encode_flags_to_addr(client));
if (status)
goto out_err;
client->dev.parent = &client->adapter->dev;
client->dev.bus = &i2c_bus_type;
client->dev.type = &i2c_client_type;
client->dev.of_node = of_node_get(info->of_node);
client->dev.fwnode = info->fwnode;
i2c_dev_set_name(adap, client, info);
if (info->properties) {
status = device_add_properties(&client->dev, info->properties);
if (status) {
dev_err(&adap->dev,
"Failed to add properties to client %s: %d\n",
client->name, status);
goto out_err_put_of_node;
}
}
status = device_register(&client->dev);
if (status)
goto out_free_props;
dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
client->name, dev_name(&client->dev));
return client;
out_free_props:
if (info->properties)
device_remove_properties(&client->dev);
out_err_put_of_node:
of_node_put(info->of_node);
out_err:
dev_err(&adap->dev,
"Failed to register i2c client %s at 0x%02x (%d)\n",
client->name, client->addr, status);
out_err_silent:
kfree(client);
return ERR_PTR(status);
}
EXPORT_SYMBOL_GPL(i2c_new_client_device);
/**
* i2c_new_device - instantiate an i2c device
* @adap: the adapter managing the device
* @info: describes one I2C device; bus_num is ignored
* Context: can sleep
*
* This deprecated function has the same functionality as
* @i2c_new_client_device, it just returns NULL instead of an ERR_PTR in case of
* an error for compatibility with current I2C API. It will be removed once all
* users are converted.
*
* This returns the new i2c client, which may be saved for later use with
* i2c_unregister_device(); or NULL to indicate an error.
*/
struct i2c_client *
i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
{
struct i2c_client *ret;
ret = i2c_new_client_device(adap, info);
return IS_ERR(ret) ? NULL : ret;
}
EXPORT_SYMBOL_GPL(i2c_new_device);
/**
* i2c_unregister_device - reverse effect of i2c_new_device()
* @client: value returned from i2c_new_device()
* Context: can sleep
*/
void i2c_unregister_device(struct i2c_client *client)
{
if (!client)
return;
if (client->dev.of_node) {
of_node_clear_flag(client->dev.of_node, OF_POPULATED);
of_node_put(client->dev.of_node);
}
if (ACPI_COMPANION(&client->dev))
acpi_device_clear_enumerated(ACPI_COMPANION(&client->dev));
device_unregister(&client->dev);
}
EXPORT_SYMBOL_GPL(i2c_unregister_device);
static const struct i2c_device_id dummy_id[] = {
{ "dummy", 0 },
{ },
};
static int dummy_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
return 0;
}
static int dummy_remove(struct i2c_client *client)
{
return 0;
}
static struct i2c_driver dummy_driver = {
.driver.name = "dummy",
.probe = dummy_probe,
.remove = dummy_remove,
.id_table = dummy_id,
};
/**
* i2c_new_dummy_device - return a new i2c device bound to a dummy driver
* @adapter: the adapter managing the device
* @address: seven bit address to be used
* Context: can sleep
*
* This returns an I2C client bound to the "dummy" driver, intended for use
* with devices that consume multiple addresses. Examples of such chips
* include various EEPROMS (like 24c04 and 24c08 models).
*
* These dummy devices have two main uses. First, most I2C and SMBus calls
* except i2c_transfer() need a client handle; the dummy will be that handle.
* And second, this prevents the specified address from being bound to a
* different driver.
*
* This returns the new i2c client, which should be saved for later use with
* i2c_unregister_device(); or an ERR_PTR to describe the error.
*/
static struct i2c_client *
i2c_new_dummy_device(struct i2c_adapter *adapter, u16 address)
{
struct i2c_board_info info = {
I2C_BOARD_INFO("dummy", address),
};
return i2c_new_client_device(adapter, &info);
}
EXPORT_SYMBOL_GPL(i2c_new_dummy_device);
/**
* i2c_new_dummy - return a new i2c device bound to a dummy driver
* @adapter: the adapter managing the device
* @address: seven bit address to be used
* Context: can sleep
*
* This deprecated function has the same functionality as @i2c_new_dummy_device,
* it just returns NULL instead of an ERR_PTR in case of an error for
* compatibility with current I2C API. It will be removed once all users are
* converted.
*
* This returns the new i2c client, which should be saved for later use with
* i2c_unregister_device(); or NULL to indicate an error.
*/
struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
{
struct i2c_client *ret;
ret = i2c_new_dummy_device(adapter, address);
return IS_ERR(ret) ? NULL : ret;
}
EXPORT_SYMBOL_GPL(i2c_new_dummy);
struct i2c_dummy_devres {
struct i2c_client *client;
};
static void devm_i2c_release_dummy(struct device *dev, void *res)
{
struct i2c_dummy_devres *this = res;
i2c_unregister_device(this->client);
}
/**
* devm_i2c_new_dummy_device - return a new i2c device bound to a dummy driver
* @dev: device the managed resource is bound to
* @adapter: the adapter managing the device
* @address: seven bit address to be used
* Context: can sleep
*
* This is the device-managed version of @i2c_new_dummy_device. It returns the
* new i2c client or an ERR_PTR in case of an error.
*/
struct i2c_client *devm_i2c_new_dummy_device(struct device *dev,
struct i2c_adapter *adapter,
u16 address)
{
struct i2c_dummy_devres *dr;
struct i2c_client *client;
dr = devres_alloc(devm_i2c_release_dummy, sizeof(*dr), GFP_KERNEL);
if (!dr)
return ERR_PTR(-ENOMEM);
client = i2c_new_dummy_device(adapter, address);
if (IS_ERR(client)) {
devres_free(dr);
} else {
dr->client = client;
devres_add(dev, dr);
}
return client;
}
EXPORT_SYMBOL_GPL(devm_i2c_new_dummy_device);
/**
* i2c_new_secondary_device - Helper to get the instantiated secondary address
* and create the associated device
* @client: Handle to the primary client
* @name: Handle to specify which secondary address to get
* @default_addr: Used as a fallback if no secondary address was specified
* Context: can sleep
*
* I2C clients can be composed of multiple I2C slaves bound together in a single
* component. The I2C client driver then binds to the master I2C slave and needs
* to create I2C dummy clients to communicate with all the other slaves.
*
* This function creates and returns an I2C dummy client whose I2C address is
* retrieved from the platform firmware based on the given slave name. If no
* address is specified by the firmware default_addr is used.
*
* On DT-based platforms the address is retrieved from the "reg" property entry
* cell whose "reg-names" value matches the slave name.
*
* This returns the new i2c client, which should be saved for later use with
* i2c_unregister_device(); or NULL to indicate an error.
*/
struct i2c_client *i2c_new_secondary_device(struct i2c_client *client,
const char *name,
u16 default_addr)
{
struct device_node *np = client->dev.of_node;
u32 addr = default_addr;
int i;
if (np) {
i = of_property_match_string(np, "reg-names", name);
if (i >= 0)
of_property_read_u32_index(np, "reg", i, &addr);
}
dev_dbg(&client->adapter->dev, "Address for %s : 0x%x\n", name, addr);
return i2c_new_dummy(client->adapter, addr);
}
EXPORT_SYMBOL_GPL(i2c_new_secondary_device);
/* ------------------------------------------------------------------------- */
/* I2C bus adapters -- one roots each I2C or SMBUS segment */
static void i2c_adapter_dev_release(struct device *dev)
{
struct i2c_adapter *adap = to_i2c_adapter(dev);
complete(&adap->dev_released);
}
unsigned int i2c_adapter_depth(struct i2c_adapter *adapter)
{
unsigned int depth = 0;
while ((adapter = i2c_parent_is_i2c_adapter(adapter)))
depth++;
WARN_ONCE(depth >= MAX_LOCKDEP_SUBCLASSES,
"adapter depth exceeds lockdep subclass limit\n");
return depth;
}
EXPORT_SYMBOL_GPL(i2c_adapter_depth);
/*
* Let users instantiate I2C devices through sysfs. This can be used when
* platform initialization code doesn't contain the proper data for
* whatever reason. Also useful for drivers that do device detection and
* detection fails, either because the device uses an unexpected address,
* or this is a compatible device with different ID register values.
*
* Parameter checking may look overzealous, but we really don't want
* the user to provide incorrect parameters.
*/
static ssize_t
i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct i2c_adapter *adap = to_i2c_adapter(dev);
struct i2c_board_info info;
struct i2c_client *client;
char *blank, end;
int res;
memset(&info, 0, sizeof(struct i2c_board_info));
blank = strchr(buf, ' ');
if (!blank) {
dev_err(dev, "%s: Missing parameters\n", "new_device");
return -EINVAL;
}
if (blank - buf > I2C_NAME_SIZE - 1) {
dev_err(dev, "%s: Invalid device name\n", "new_device");
return -EINVAL;
}
memcpy(info.type, buf, blank - buf);
/* Parse remaining parameters, reject extra parameters */
res = sscanf(++blank, "%hi%c", &info.addr, &end);
if (res < 1) {
dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
return -EINVAL;
}
if (res > 1 && end != '\n') {
dev_err(dev, "%s: Extra parameters\n", "new_device");
return -EINVAL;
}
if ((info.addr & I2C_ADDR_OFFSET_TEN_BIT) == I2C_ADDR_OFFSET_TEN_BIT) {
info.addr &= ~I2C_ADDR_OFFSET_TEN_BIT;
info.flags |= I2C_CLIENT_TEN;
}
if (info.addr & I2C_ADDR_OFFSET_SLAVE) {
info.addr &= ~I2C_ADDR_OFFSET_SLAVE;
info.flags |= I2C_CLIENT_SLAVE;
}
client = i2c_new_client_device(adap, &info);
if (IS_ERR(client))
return PTR_ERR(client);
/* Keep track of the added device */
mutex_lock(&adap->userspace_clients_lock);
list_add_tail(&client->detected, &adap->userspace_clients);
mutex_unlock(&adap->userspace_clients_lock);
dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
info.type, info.addr);
return count;
}
static DEVICE_ATTR(new_device, S_IWUSR, NULL, i2c_sysfs_new_device);
/*
* And of course let the users delete the devices they instantiated, if
* they got it wrong. This interface can only be used to delete devices
* instantiated by i2c_sysfs_new_device above. This guarantees that we
* don't delete devices to which some kernel code still has references.
*
* Parameter checking may look overzealous, but we really don't want
* the user to delete the wrong device.
*/
static ssize_t
i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct i2c_adapter *adap = to_i2c_adapter(dev);
struct i2c_client *client, *next;
unsigned short addr;
char end;
int res;
/* Parse parameters, reject extra parameters */
res = sscanf(buf, "%hi%c", &addr, &end);
if (res < 1) {
dev_err(dev, "%s: Can't parse I2C address\n", "delete_device");
return -EINVAL;
}
if (res > 1 && end != '\n') {
dev_err(dev, "%s: Extra parameters\n", "delete_device");
return -EINVAL;
}
/* Make sure the device was added through sysfs */
res = -ENOENT;
mutex_lock_nested(&adap->userspace_clients_lock,
i2c_adapter_depth(adap));
list_for_each_entry_safe(client, next, &adap->userspace_clients,
detected) {
if (i2c_encode_flags_to_addr(client) == addr) {
dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
"delete_device", client->name, client->addr);
list_del(&client->detected);
i2c_unregister_device(client);
res = count;
break;
}
}
mutex_unlock(&adap->userspace_clients_lock);
if (res < 0)
dev_err(dev, "%s: Can't find device in list\n",
"delete_device");
return res;
}
static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, S_IWUSR, NULL,
i2c_sysfs_delete_device);
static struct attribute *i2c_adapter_attrs[] = {
&dev_attr_name.attr,
&dev_attr_new_device.attr,
&dev_attr_delete_device.attr,
NULL
};
ATTRIBUTE_GROUPS(i2c_adapter);
struct device_type i2c_adapter_type = {
.groups = i2c_adapter_groups,
.release = i2c_adapter_dev_release,
};
EXPORT_SYMBOL_GPL(i2c_adapter_type);
/**
* i2c_verify_adapter - return parameter as i2c_adapter or NULL
* @dev: device, probably from some driver model iterator
*
* When traversing the driver model tree, perhaps using driver model
* iterators like @device_for_each_child(), you can't assume very much
* about the nodes you find. Use this function to avoid oopses caused
* by wrongly treating some non-I2C device as an i2c_adapter.
*/
struct i2c_adapter *i2c_verify_adapter(struct device *dev)
{
return (dev->type == &i2c_adapter_type)
? to_i2c_adapter(dev)
: NULL;
}
EXPORT_SYMBOL(i2c_verify_adapter);
#ifdef CONFIG_I2C_COMPAT
static struct class_compat *i2c_adapter_compat_class;
#endif
static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
{
struct i2c_devinfo *devinfo;
down_read(&__i2c_board_lock);
list_for_each_entry(devinfo, &__i2c_board_list, list) {
if (devinfo->busnum == adapter->nr
&& !i2c_new_device(adapter,
&devinfo->board_info))
dev_err(&adapter->dev,
"Can't create device at 0x%02x\n",
devinfo->board_info.addr);
}
up_read(&__i2c_board_lock);
}
static int i2c_do_add_adapter(struct i2c_driver *driver,
struct i2c_adapter *adap)
{
/* Detect supported devices on that bus, and instantiate them */
i2c_detect(adap, driver);
return 0;
}
static int __process_new_adapter(struct device_driver *d, void *data)
{
return i2c_do_add_adapter(to_i2c_driver(d), data);
}
static const struct i2c_lock_operations i2c_adapter_lock_ops = {
.lock_bus = i2c_adapter_lock_bus,
.trylock_bus = i2c_adapter_trylock_bus,
.unlock_bus = i2c_adapter_unlock_bus,
};
static void i2c_host_notify_irq_teardown(struct i2c_adapter *adap)
{
struct irq_domain *domain = adap->host_notify_domain;
irq_hw_number_t hwirq;
if (!domain)
return;
for (hwirq = 0 ; hwirq < I2C_ADDR_7BITS_COUNT ; hwirq++)
irq_dispose_mapping(irq_find_mapping(domain, hwirq));
irq_domain_remove(domain);
adap->host_notify_domain = NULL;
}
static int i2c_host_notify_irq_map(struct irq_domain *h,
unsigned int virq,
irq_hw_number_t hw_irq_num)
{
irq_set_chip_and_handler(virq, &dummy_irq_chip, handle_simple_irq);
return 0;
}
static const struct irq_domain_ops i2c_host_notify_irq_ops = {
.map = i2c_host_notify_irq_map,
};
static int i2c_setup_host_notify_irq_domain(struct i2c_adapter *adap)
{
struct irq_domain *domain;
if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_HOST_NOTIFY))
return 0;
domain = irq_domain_create_linear(adap->dev.fwnode,
I2C_ADDR_7BITS_COUNT,
&i2c_host_notify_irq_ops, adap);
if (!domain)
return -ENOMEM;
adap->host_notify_domain = domain;
return 0;
}
/**
* i2c_handle_smbus_host_notify - Forward a Host Notify event to the correct
* I2C client.
* @adap: the adapter
* @addr: the I2C address of the notifying device
* Context: can't sleep
*
* Helper function to be called from an I2C bus driver's interrupt
* handler. It will schedule the Host Notify IRQ.
*/
int i2c_handle_smbus_host_notify(struct i2c_adapter *adap, unsigned short addr)
{
int irq;
if (!adap)
return -EINVAL;
irq = irq_find_mapping(adap->host_notify_domain, addr);
if (irq <= 0)
return -ENXIO;
generic_handle_irq(irq);
return 0;
}
EXPORT_SYMBOL_GPL(i2c_handle_smbus_host_notify);
static int i2c_register_adapter(struct i2c_adapter *adap)
{
int res = -EINVAL;
/* Can't register until after driver model init */
if (WARN_ON(!is_registered)) {
res = -EAGAIN;
goto out_list;
}
/* Sanity checks */
if (WARN(!adap->name[0], "i2c adapter has no name"))
goto out_list;
if (!adap->algo) {
pr_err("adapter '%s': no algo supplied!\n", adap->name);
goto out_list;
}
if (!adap->lock_ops)
adap->lock_ops = &i2c_adapter_lock_ops;
adap->locked_flags = 0;
rt_mutex_init(&adap->bus_lock);
rt_mutex_init(&adap->mux_lock);
mutex_init(&adap->userspace_clients_lock);
INIT_LIST_HEAD(&adap->userspace_clients);
/* Set default timeout to 1 second if not already set */
if (adap->timeout == 0)
adap->timeout = HZ;
/* register soft irqs for Host Notify */
res = i2c_setup_host_notify_irq_domain(adap);
if (res) {
pr_err("adapter '%s': can't create Host Notify IRQs (%d)\n",
adap->name, res);
goto out_list;
}
dev_set_name(&adap->dev, "i2c-%d", adap->nr);
adap->dev.bus = &i2c_bus_type;
adap->dev.type = &i2c_adapter_type;
res = device_register(&adap->dev);
if (res) {
pr_err("adapter '%s': can't register device (%d)\n", adap->name, res);
goto out_list;
}
res = of_i2c_setup_smbus_alert(adap);
if (res)
goto out_reg;
dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
pm_runtime_no_callbacks(&adap->dev);
pm_suspend_ignore_children(&adap->dev, true);
pm_runtime_enable(&adap->dev);
#ifdef CONFIG_I2C_COMPAT
res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev,
adap->dev.parent);
if (res)
dev_warn(&adap->dev,
"Failed to create compatibility class link\n");
#endif
i2c_init_recovery(adap);
/* create pre-declared device nodes */
of_i2c_register_devices(adap);
i2c_acpi_register_devices(adap);
i2c_acpi_install_space_handler(adap);
if (adap->nr < __i2c_first_dynamic_bus_num)
i2c_scan_static_board_info(adap);
/* Notify drivers */
mutex_lock(&core_lock);
bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter);
mutex_unlock(&core_lock);
return 0;
out_reg:
init_completion(&adap->dev_released);
device_unregister(&adap->dev);
wait_for_completion(&adap->dev_released);
out_list:
mutex_lock(&core_lock);
idr_remove(&i2c_adapter_idr, adap->nr);
mutex_unlock(&core_lock);
return res;
}
/**
* __i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1
* @adap: the adapter to register (with adap->nr initialized)
* Context: can sleep
*
* See i2c_add_numbered_adapter() for details.
*/
static int __i2c_add_numbered_adapter(struct i2c_adapter *adap)
{
int id;
mutex_lock(&core_lock);
id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1, GFP_KERNEL);
mutex_unlock(&core_lock);
if (WARN(id < 0, "couldn't get idr"))
return id == -ENOSPC ? -EBUSY : id;
return i2c_register_adapter(adap);
}
/**
* i2c_add_adapter - declare i2c adapter, use dynamic bus number
* @adapter: the adapter to add
* Context: can sleep
*
* This routine is used to declare an I2C adapter when its bus number
* doesn't matter or when its bus number is specified by an dt alias.
* Examples of bases when the bus number doesn't matter: I2C adapters
* dynamically added by USB links or PCI plugin cards.
*
* When this returns zero, a new bus number was allocated and stored
* in adap->nr, and the specified adapter became available for clients.
* Otherwise, a negative errno value is returned.
*/
int i2c_add_adapter(struct i2c_adapter *adapter)
{
struct device *dev = &adapter->dev;
int id;
if (dev->of_node) {
id = of_alias_get_id(dev->of_node, "i2c");
if (id >= 0) {
adapter->nr = id;
return __i2c_add_numbered_adapter(adapter);
}
}
mutex_lock(&core_lock);
id = idr_alloc(&i2c_adapter_idr, adapter,
__i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
mutex_unlock(&core_lock);
if (WARN(id < 0, "couldn't get idr"))
return id;
adapter->nr = id;
return i2c_register_adapter(adapter);
}
EXPORT_SYMBOL(i2c_add_adapter);
/**
* i2c_add_numbered_adapter - declare i2c adapter, use static bus number
* @adap: the adapter to register (with adap->nr initialized)
* Context: can sleep
*
* This routine is used to declare an I2C adapter when its bus number
* matters. For example, use it for I2C adapters from system-on-chip CPUs,
* or otherwise built in to the system's mainboard, and where i2c_board_info
* is used to properly configure I2C devices.
*
* If the requested bus number is set to -1, then this function will behave
* identically to i2c_add_adapter, and will dynamically assign a bus number.
*
* If no devices have pre-been declared for this bus, then be sure to
* register the adapter before any dynamically allocated ones. Otherwise
* the required bus ID may not be available.
*
* When this returns zero, the specified adapter became available for
* clients using the bus number provided in adap->nr. Also, the table
* of I2C devices pre-declared using i2c_register_board_info() is scanned,
* and the appropriate driver model device nodes are created. Otherwise, a
* negative errno value is returned.
*/
int i2c_add_numbered_adapter(struct i2c_adapter *adap)
{
if (adap->nr == -1) /* -1 means dynamically assign bus id */
return i2c_add_adapter(adap);
return __i2c_add_numbered_adapter(adap);
}
EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
static void i2c_do_del_adapter(struct i2c_driver *driver,
struct i2c_adapter *adapter)
{
struct i2c_client *client, *_n;
/* Remove the devices we created ourselves as the result of hardware
* probing (using a driver's detect method) */
list_for_each_entry_safe(client, _n, &driver->clients, detected) {
if (client->adapter == adapter) {
dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
client->name, client->addr);
list_del(&client->detected);
i2c_unregister_device(client);
}
}
}
static int __unregister_client(struct device *dev, void *dummy)
{
struct i2c_client *client = i2c_verify_client(dev);
if (client && strcmp(client->name, "dummy"))
i2c_unregister_device(client);
return 0;
}
static int __unregister_dummy(struct device *dev, void *dummy)
{
struct i2c_client *client = i2c_verify_client(dev);
i2c_unregister_device(client);
return 0;
}
static int __process_removed_adapter(struct device_driver *d, void *data)
{
i2c_do_del_adapter(to_i2c_driver(d), data);
return 0;
}
/**
* i2c_del_adapter - unregister I2C adapter
* @adap: the adapter being unregistered
* Context: can sleep
*
* This unregisters an I2C adapter which was previously registered
* by @i2c_add_adapter or @i2c_add_numbered_adapter.
*/
void i2c_del_adapter(struct i2c_adapter *adap)
{
struct i2c_adapter *found;
struct i2c_client *client, *next;
/* First make sure that this adapter was ever added */
mutex_lock(&core_lock);
found = idr_find(&i2c_adapter_idr, adap->nr);
mutex_unlock(&core_lock);
if (found != adap) {
pr_debug("attempting to delete unregistered adapter [%s]\n", adap->name);
return;
}
i2c_acpi_remove_space_handler(adap);
/* Tell drivers about this removal */
mutex_lock(&core_lock);
bus_for_each_drv(&i2c_bus_type, NULL, adap,
__process_removed_adapter);
mutex_unlock(&core_lock);
/* Remove devices instantiated from sysfs */
mutex_lock_nested(&adap->userspace_clients_lock,
i2c_adapter_depth(adap));
list_for_each_entry_safe(client, next, &adap->userspace_clients,
detected) {
dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
client->addr);
list_del(&client->detected);
i2c_unregister_device(client);
}
mutex_unlock(&adap->userspace_clients_lock);
/* Detach any active clients. This can't fail, thus we do not
* check the returned value. This is a two-pass process, because
* we can't remove the dummy devices during the first pass: they
* could have been instantiated by real devices wishing to clean
* them up properly, so we give them a chance to do that first. */
device_for_each_child(&adap->dev, NULL, __unregister_client);
device_for_each_child(&adap->dev, NULL, __unregister_dummy);
#ifdef CONFIG_I2C_COMPAT
class_compat_remove_link(i2c_adapter_compat_class, &adap->dev,
adap->dev.parent);
#endif
/* device name is gone after device_unregister */
dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
pm_runtime_disable(&adap->dev);
i2c_host_notify_irq_teardown(adap);
/* wait until all references to the device are gone
*
* FIXME: This is old code and should ideally be replaced by an
* alternative which results in decoupling the lifetime of the struct
* device from the i2c_adapter, like spi or netdev do. Any solution
* should be thoroughly tested with DEBUG_KOBJECT_RELEASE enabled!
*/
init_completion(&adap->dev_released);
device_unregister(&adap->dev);
wait_for_completion(&adap->dev_released);
/* free bus id */
mutex_lock(&core_lock);
idr_remove(&i2c_adapter_idr, adap->nr);
mutex_unlock(&core_lock);
/* Clear the device structure in case this adapter is ever going to be
added again */
memset(&adap->dev, 0, sizeof(adap->dev));
}
EXPORT_SYMBOL(i2c_del_adapter);
/**
* i2c_parse_fw_timings - get I2C related timing parameters from firmware
* @dev: The device to scan for I2C timing properties
* @t: the i2c_timings struct to be filled with values
* @use_defaults: bool to use sane defaults derived from the I2C specification
* when properties are not found, otherwise use 0
*
* Scan the device for the generic I2C properties describing timing parameters
* for the signal and fill the given struct with the results. If a property was
* not found and use_defaults was true, then maximum timings are assumed which
* are derived from the I2C specification. If use_defaults is not used, the
* results will be 0, so drivers can apply their own defaults later. The latter
* is mainly intended for avoiding regressions of existing drivers which want
* to switch to this function. New drivers almost always should use the defaults.
*/
void i2c_parse_fw_timings(struct device *dev, struct i2c_timings *t, bool use_defaults)
{
int ret;
memset(t, 0, sizeof(*t));
ret = device_property_read_u32(dev, "clock-frequency", &t->bus_freq_hz);
if (ret && use_defaults)
t->bus_freq_hz = 100000;
ret = device_property_read_u32(dev, "i2c-scl-rising-time-ns", &t->scl_rise_ns);
if (ret && use_defaults) {
if (t->bus_freq_hz <= 100000)
t->scl_rise_ns = 1000;
else if (t->bus_freq_hz <= 400000)
t->scl_rise_ns = 300;
else
t->scl_rise_ns = 120;
}
ret = device_property_read_u32(dev, "i2c-scl-falling-time-ns", &t->scl_fall_ns);
if (ret && use_defaults) {
if (t->bus_freq_hz <= 400000)
t->scl_fall_ns = 300;
else
t->scl_fall_ns = 120;
}
device_property_read_u32(dev, "i2c-scl-internal-delay-ns", &t->scl_int_delay_ns);
ret = device_property_read_u32(dev, "i2c-sda-falling-time-ns", &t->sda_fall_ns);
if (ret && use_defaults)
t->sda_fall_ns = t->scl_fall_ns;
device_property_read_u32(dev, "i2c-sda-hold-time-ns", &t->sda_hold_ns);
}
EXPORT_SYMBOL_GPL(i2c_parse_fw_timings);
/* ------------------------------------------------------------------------- */
int i2c_for_each_dev(void *data, int (*fn)(struct device *, void *))
{
int res;
mutex_lock(&core_lock);
res = bus_for_each_dev(&i2c_bus_type, NULL, data, fn);
mutex_unlock(&core_lock);
return res;
}
EXPORT_SYMBOL_GPL(i2c_for_each_dev);
static int __process_new_driver(struct device *dev, void *data)
{
if (dev->type != &i2c_adapter_type)
return 0;
return i2c_do_add_adapter(data, to_i2c_adapter(dev));
}
/*
* An i2c_driver is used with one or more i2c_client (device) nodes to access
* i2c slave chips, on a bus instance associated with some i2c_adapter.
*/
int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
{
int res;
/* Can't register until after driver model init */
if (WARN_ON(!is_registered))
return -EAGAIN;
/* add the driver to the list of i2c drivers in the driver core */
driver->driver.owner = owner;
driver->driver.bus = &i2c_bus_type;
INIT_LIST_HEAD(&driver->clients);
/* When registration returns, the driver core
* will have called probe() for all matching-but-unbound devices.
*/
res = driver_register(&driver->driver);
if (res)
return res;
pr_debug("driver [%s] registered\n", driver->driver.name);
/* Walk the adapters that are already present */
i2c_for_each_dev(driver, __process_new_driver);
return 0;
}
EXPORT_SYMBOL(i2c_register_driver);
static int __process_removed_driver(struct device *dev, void *data)
{
if (dev->type == &i2c_adapter_type)
i2c_do_del_adapter(data, to_i2c_adapter(dev));
return 0;
}
/**
* i2c_del_driver - unregister I2C driver
* @driver: the driver being unregistered
* Context: can sleep
*/
void i2c_del_driver(struct i2c_driver *driver)
{
i2c_for_each_dev(driver, __process_removed_driver);
driver_unregister(&driver->driver);
pr_debug("driver [%s] unregistered\n", driver->driver.name);
}
EXPORT_SYMBOL(i2c_del_driver);
/* ------------------------------------------------------------------------- */
/**
* i2c_use_client - increments the reference count of the i2c client structure
* @client: the client being referenced
*
* Each live reference to a client should be refcounted. The driver model does
* that automatically as part of driver binding, so that most drivers don't
* need to do this explicitly: they hold a reference until they're unbound
* from the device.
*
* A pointer to the client with the incremented reference counter is returned.
*/
struct i2c_client *i2c_use_client(struct i2c_client *client)
{
if (client && get_device(&client->dev))
return client;
return NULL;
}
EXPORT_SYMBOL(i2c_use_client);
/**
* i2c_release_client - release a use of the i2c client structure
* @client: the client being no longer referenced
*
* Must be called when a user of a client is finished with it.
*/
void i2c_release_client(struct i2c_client *client)
{
if (client)
put_device(&client->dev);
}
EXPORT_SYMBOL(i2c_release_client);
struct i2c_cmd_arg {
unsigned cmd;
void *arg;
};
static int i2c_cmd(struct device *dev, void *_arg)
{
struct i2c_client *client = i2c_verify_client(dev);
struct i2c_cmd_arg *arg = _arg;
struct i2c_driver *driver;
if (!client || !client->dev.driver)
return 0;
driver = to_i2c_driver(client->dev.driver);
if (driver->command)
driver->command(client, arg->cmd, arg->arg);
return 0;
}
void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
{
struct i2c_cmd_arg cmd_arg;
cmd_arg.cmd = cmd;
cmd_arg.arg = arg;
device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd);
}
EXPORT_SYMBOL(i2c_clients_command);
static int __init i2c_init(void)
{
int retval;
retval = of_alias_get_highest_id("i2c");
down_write(&__i2c_board_lock);
if (retval >= __i2c_first_dynamic_bus_num)
__i2c_first_dynamic_bus_num = retval + 1;
up_write(&__i2c_board_lock);
retval = bus_register(&i2c_bus_type);
if (retval)
return retval;
is_registered = true;
#ifdef CONFIG_I2C_COMPAT
i2c_adapter_compat_class = class_compat_register("i2c-adapter");
if (!i2c_adapter_compat_class) {
retval = -ENOMEM;
goto bus_err;
}
#endif
retval = i2c_add_driver(&dummy_driver);
if (retval)
goto class_err;
if (IS_ENABLED(CONFIG_OF_DYNAMIC))
WARN_ON(of_reconfig_notifier_register(&i2c_of_notifier));
if (IS_ENABLED(CONFIG_ACPI))
WARN_ON(acpi_reconfig_notifier_register(&i2c_acpi_notifier));
return 0;
class_err:
#ifdef CONFIG_I2C_COMPAT
class_compat_unregister(i2c_adapter_compat_class);
bus_err:
#endif
is_registered = false;
bus_unregister(&i2c_bus_type);
return retval;
}
static void __exit i2c_exit(void)
{
if (IS_ENABLED(CONFIG_ACPI))
WARN_ON(acpi_reconfig_notifier_unregister(&i2c_acpi_notifier));
if (IS_ENABLED(CONFIG_OF_DYNAMIC))
WARN_ON(of_reconfig_notifier_unregister(&i2c_of_notifier));
i2c_del_driver(&dummy_driver);
#ifdef CONFIG_I2C_COMPAT
class_compat_unregister(i2c_adapter_compat_class);
#endif
bus_unregister(&i2c_bus_type);
tracepoint_synchronize_unregister();
}
/* We must initialize early, because some subsystems register i2c drivers
* in subsys_initcall() code, but are linked (and initialized) before i2c.
*/
postcore_initcall(i2c_init);
module_exit(i2c_exit);
/* ----------------------------------------------------
* the functional interface to the i2c busses.
* ----------------------------------------------------
*/
/* Check if val is exceeding the quirk IFF quirk is non 0 */
#define i2c_quirk_exceeded(val, quirk) ((quirk) && ((val) > (quirk)))
static int i2c_quirk_error(struct i2c_adapter *adap, struct i2c_msg *msg, char *err_msg)
{
dev_err_ratelimited(&adap->dev, "adapter quirk: %s (addr 0x%04x, size %u, %s)\n",
err_msg, msg->addr, msg->len,
msg->flags & I2C_M_RD ? "read" : "write");
return -EOPNOTSUPP;
}
static int i2c_check_for_quirks(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
{
const struct i2c_adapter_quirks *q = adap->quirks;
int max_num = q->max_num_msgs, i;
bool do_len_check = true;
if (q->flags & I2C_AQ_COMB) {
max_num = 2;
/* special checks for combined messages */
if (num == 2) {
if (q->flags & I2C_AQ_COMB_WRITE_FIRST && msgs[0].flags & I2C_M_RD)
return i2c_quirk_error(adap, &msgs[0], "1st comb msg must be write");
if (q->flags & I2C_AQ_COMB_READ_SECOND && !(msgs[1].flags & I2C_M_RD))
return i2c_quirk_error(adap, &msgs[1], "2nd comb msg must be read");
if (q->flags & I2C_AQ_COMB_SAME_ADDR && msgs[0].addr != msgs[1].addr)
return i2c_quirk_error(adap, &msgs[0], "comb msg only to same addr");
if (i2c_quirk_exceeded(msgs[0].len, q->max_comb_1st_msg_len))
return i2c_quirk_error(adap, &msgs[0], "msg too long");
if (i2c_quirk_exceeded(msgs[1].len, q->max_comb_2nd_msg_len))
return i2c_quirk_error(adap, &msgs[1], "msg too long");
do_len_check = false;
}
}
if (i2c_quirk_exceeded(num, max_num))
return i2c_quirk_error(adap, &msgs[0], "too many messages");
for (i = 0; i < num; i++) {
u16 len = msgs[i].len;
if (msgs[i].flags & I2C_M_RD) {
if (do_len_check && i2c_quirk_exceeded(len, q->max_read_len))
return i2c_quirk_error(adap, &msgs[i], "msg too long");
if (q->flags & I2C_AQ_NO_ZERO_LEN_READ && len == 0)
return i2c_quirk_error(adap, &msgs[i], "no zero length");
} else {
if (do_len_check && i2c_quirk_exceeded(len, q->max_write_len))
return i2c_quirk_error(adap, &msgs[i], "msg too long");
if (q->flags & I2C_AQ_NO_ZERO_LEN_WRITE && len == 0)
return i2c_quirk_error(adap, &msgs[i], "no zero length");
}
}
return 0;
}
/**
* __i2c_transfer - unlocked flavor of i2c_transfer
* @adap: Handle to I2C bus
* @msgs: One or more messages to execute before STOP is issued to
* terminate the operation; each message begins with a START.
* @num: Number of messages to be executed.
*
* Returns negative errno, else the number of messages executed.
*
* Adapter lock must be held when calling this function. No debug logging
* takes place. adap->algo->master_xfer existence isn't checked.
*/
int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
{
unsigned long orig_jiffies;
int ret, try;
if (WARN_ON(!msgs || num < 1))
return -EINVAL;
ret = __i2c_check_suspended(adap);
if (ret)
return ret;
if (adap->quirks && i2c_check_for_quirks(adap, msgs, num))
return -EOPNOTSUPP;
/*
* i2c_trace_msg_key gets enabled when tracepoint i2c_transfer gets
* enabled. This is an efficient way of keeping the for-loop from
* being executed when not needed.
*/
if (static_branch_unlikely(&i2c_trace_msg_key)) {
int i;
for (i = 0; i < num; i++)
if (msgs[i].flags & I2C_M_RD)
trace_i2c_read(adap, &msgs[i], i);
else
trace_i2c_write(adap, &msgs[i], i);
}
/* Retry automatically on arbitration loss */
orig_jiffies = jiffies;
for (ret = 0, try = 0; try <= adap->retries; try++) {
if (i2c_in_atomic_xfer_mode() && adap->algo->master_xfer_atomic)
ret = adap->algo->master_xfer_atomic(adap, msgs, num);
else
ret = adap->algo->master_xfer(adap, msgs, num);
if (ret != -EAGAIN)
break;
if (time_after(jiffies, orig_jiffies + adap->timeout))
break;
}
if (static_branch_unlikely(&i2c_trace_msg_key)) {
int i;
for (i = 0; i < ret; i++)
if (msgs[i].flags & I2C_M_RD)
trace_i2c_reply(adap, &msgs[i], i);
trace_i2c_result(adap, num, ret);
}
return ret;
}
EXPORT_SYMBOL(__i2c_transfer);
/**
* i2c_transfer - execute a single or combined I2C message
* @adap: Handle to I2C bus
* @msgs: One or more messages to execute before STOP is issued to
* terminate the operation; each message begins with a START.
* @num: Number of messages to be executed.
*
* Returns negative errno, else the number of messages executed.
*
* Note that there is no requirement that each message be sent to
* the same slave address, although that is the most common model.
*/
int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
{
int ret;
if (!adap->algo->master_xfer) {
dev_dbg(&adap->dev, "I2C level transfers not supported\n");
return -EOPNOTSUPP;
}
/* REVISIT the fault reporting model here is weak:
*
* - When we get an error after receiving N bytes from a slave,
* there is no way to report "N".
*
* - When we get a NAK after transmitting N bytes to a slave,
* there is no way to report "N" ... or to let the master
* continue executing the rest of this combined message, if
* that's the appropriate response.
*
* - When for example "num" is two and we successfully complete
* the first message but get an error part way through the
* second, it's unclear whether that should be reported as
* one (discarding status on the second message) or errno
* (discarding status on the first one).
*/
ret = __i2c_lock_bus_helper(adap);
if (ret)
return ret;
ret = __i2c_transfer(adap, msgs, num);
i2c_unlock_bus(adap, I2C_LOCK_SEGMENT);
return ret;
}
EXPORT_SYMBOL(i2c_transfer);
/**
* i2c_transfer_buffer_flags - issue a single I2C message transferring data
* to/from a buffer
* @client: Handle to slave device
* @buf: Where the data is stored
* @count: How many bytes to transfer, must be less than 64k since msg.len is u16
* @flags: The flags to be used for the message, e.g. I2C_M_RD for reads
*
* Returns negative errno, or else the number of bytes transferred.
*/
int i2c_transfer_buffer_flags(const struct i2c_client *client, char *buf,
int count, u16 flags)
{
int ret;
struct i2c_msg msg = {
.addr = client->addr,
.flags = flags | (client->flags & I2C_M_TEN),
.len = count,
.buf = buf,
};
ret = i2c_transfer(client->adapter, &msg, 1);
/*
* If everything went ok (i.e. 1 msg transferred), return #bytes
* transferred, else error code.
*/
return (ret == 1) ? count : ret;
}
EXPORT_SYMBOL(i2c_transfer_buffer_flags);
/**
* i2c_get_device_id - get manufacturer, part id and die revision of a device
* @client: The device to query
* @id: The queried information
*
* Returns negative errno on error, zero on success.
*/
int i2c_get_device_id(const struct i2c_client *client,
struct i2c_device_identity *id)
{
struct i2c_adapter *adap = client->adapter;
union i2c_smbus_data raw_id;
int ret;
if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
return -EOPNOTSUPP;
raw_id.block[0] = 3;
ret = i2c_smbus_xfer(adap, I2C_ADDR_DEVICE_ID, 0,
I2C_SMBUS_READ, client->addr << 1,
I2C_SMBUS_I2C_BLOCK_DATA, &raw_id);
if (ret)
return ret;
id->manufacturer_id = (raw_id.block[1] << 4) | (raw_id.block[2] >> 4);
id->part_id = ((raw_id.block[2] & 0xf) << 5) | (raw_id.block[3] >> 3);
id->die_revision = raw_id.block[3] & 0x7;
return 0;
}
EXPORT_SYMBOL_GPL(i2c_get_device_id);
/* ----------------------------------------------------
* the i2c address scanning function
* Will not work for 10-bit addresses!
* ----------------------------------------------------
*/
/*
* Legacy default probe function, mostly relevant for SMBus. The default
* probe method is a quick write, but it is known to corrupt the 24RF08
* EEPROMs due to a state machine bug, and could also irreversibly
* write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f,
* we use a short byte read instead. Also, some bus drivers don't implement
* quick write, so we fallback to a byte read in that case too.
* On x86, there is another special case for FSC hardware monitoring chips,
* which want regular byte reads (address 0x73.) Fortunately, these are the
* only known chips using this I2C address on PC hardware.
* Returns 1 if probe succeeded, 0 if not.
*/
static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr)
{
int err;
union i2c_smbus_data dummy;
#ifdef CONFIG_X86
if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON)
&& i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA))
err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
I2C_SMBUS_BYTE_DATA, &dummy);
else
#endif
if (!((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50)
&& i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK))
err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0,
I2C_SMBUS_QUICK, NULL);
else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE))
err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
I2C_SMBUS_BYTE, &dummy);
else {
dev_warn(&adap->dev, "No suitable probing method supported for address 0x%02X\n",
addr);
err = -EOPNOTSUPP;
}
return err >= 0;
}
static int i2c_detect_address(struct i2c_client *temp_client,
struct i2c_driver *driver)
{
struct i2c_board_info info;
struct i2c_adapter *adapter = temp_client->adapter;
int addr = temp_client->addr;
int err;
/* Make sure the address is valid */
err = i2c_check_7bit_addr_validity_strict(addr);
if (err) {
dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
addr);
return err;
}
/* Skip if already in use (7 bit, no need to encode flags) */
if (i2c_check_addr_busy(adapter, addr))
return 0;
/* Make sure there is something at this address */
if (!i2c_default_probe(adapter, addr))
return 0;
/* Finally call the custom detection function */
memset(&info, 0, sizeof(struct i2c_board_info));
info.addr = addr;
err = driver->detect(temp_client, &info);
if (err) {
/* -ENODEV is returned if the detection fails. We catch it
here as this isn't an error. */
return err == -ENODEV ? 0 : err;
}
/* Consistency check */
if (info.type[0] == '\0') {
dev_err(&adapter->dev,
"%s detection function provided no name for 0x%x\n",
driver->driver.name, addr);
} else {
struct i2c_client *client;
/* Detection succeeded, instantiate the device */
if (adapter->class & I2C_CLASS_DEPRECATED)
dev_warn(&adapter->dev,
"This adapter will soon drop class based instantiation of devices. "
"Please make sure client 0x%02x gets instantiated by other means. "
"Check 'Documentation/i2c/instantiating-devices' for details.\n",
info.addr);
dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
info.type, info.addr);
client = i2c_new_device(adapter, &info);
if (client)
list_add_tail(&client->detected, &driver->clients);
else
dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
info.type, info.addr);
}
return 0;
}
static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
{
const unsigned short *address_list;
struct i2c_client *temp_client;
int i, err = 0;
int adap_id = i2c_adapter_id(adapter);
address_list = driver->address_list;
if (!driver->detect || !address_list)
return 0;
/* Warn that the adapter lost class based instantiation */
if (adapter->class == I2C_CLASS_DEPRECATED) {
dev_dbg(&adapter->dev,
"This adapter dropped support for I2C classes and won't auto-detect %s devices anymore. "
"If you need it, check 'Documentation/i2c/instantiating-devices' for alternatives.\n",
driver->driver.name);
return 0;
}
/* Stop here if the classes do not match */
if (!(adapter->class & driver->class))
return 0;
/* Set up a temporary client to help detect callback */
temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
if (!temp_client)
return -ENOMEM;
temp_client->adapter = adapter;
for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
dev_dbg(&adapter->dev,
"found normal entry for adapter %d, addr 0x%02x\n",
adap_id, address_list[i]);
temp_client->addr = address_list[i];
err = i2c_detect_address(temp_client, driver);
if (unlikely(err))
break;
}
kfree(temp_client);
return err;
}
int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr)
{
return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
I2C_SMBUS_QUICK, NULL) >= 0;
}
EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
struct i2c_client *
i2c_new_probed_device(struct i2c_adapter *adap,
struct i2c_board_info *info,
unsigned short const *addr_list,
int (*probe)(struct i2c_adapter *, unsigned short addr))
{
int i;
if (!probe)
probe = i2c_default_probe;
for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {
/* Check address validity */
if (i2c_check_7bit_addr_validity_strict(addr_list[i]) < 0) {
dev_warn(&adap->dev, "Invalid 7-bit address 0x%02x\n",
addr_list[i]);
continue;
}
/* Check address availability (7 bit, no need to encode flags) */
if (i2c_check_addr_busy(adap, addr_list[i])) {
dev_dbg(&adap->dev,
"Address 0x%02x already in use, not probing\n",
addr_list[i]);
continue;
}
/* Test address responsiveness */
if (probe(adap, addr_list[i]))
break;
}
if (addr_list[i] == I2C_CLIENT_END) {
dev_dbg(&adap->dev, "Probing failed, no device found\n");
return NULL;
}
info->addr = addr_list[i];
return i2c_new_device(adap, info);
}
EXPORT_SYMBOL_GPL(i2c_new_probed_device);
struct i2c_adapter *i2c_get_adapter(int nr)
{
struct i2c_adapter *adapter;
mutex_lock(&core_lock);
adapter = idr_find(&i2c_adapter_idr, nr);
if (!adapter)
goto exit;
if (try_module_get(adapter->owner))
get_device(&adapter->dev);
else
adapter = NULL;
exit:
mutex_unlock(&core_lock);
return adapter;
}
EXPORT_SYMBOL(i2c_get_adapter);
void i2c_put_adapter(struct i2c_adapter *adap)
{
if (!adap)
return;
put_device(&adap->dev);
module_put(adap->owner);
}
EXPORT_SYMBOL(i2c_put_adapter);
/**
* i2c_get_dma_safe_msg_buf() - get a DMA safe buffer for the given i2c_msg
* @msg: the message to be checked
* @threshold: the minimum number of bytes for which using DMA makes sense.
* Should at least be 1.
*
* Return: NULL if a DMA safe buffer was not obtained. Use msg->buf with PIO.
* Or a valid pointer to be used with DMA. After use, release it by
* calling i2c_put_dma_safe_msg_buf().
*
* This function must only be called from process context!
*/
u8 *i2c_get_dma_safe_msg_buf(struct i2c_msg *msg, unsigned int threshold)
{
/* also skip 0-length msgs for bogus thresholds of 0 */
if (!threshold)
pr_debug("DMA buffer for addr=0x%02x with length 0 is bogus\n",
msg->addr);
if (msg->len < threshold || msg->len == 0)
return NULL;
if (msg->flags & I2C_M_DMA_SAFE)
return msg->buf;
pr_debug("using bounce buffer for addr=0x%02x, len=%d\n",
msg->addr, msg->len);
if (msg->flags & I2C_M_RD)
return kzalloc(msg->len, GFP_KERNEL);
else
return kmemdup(msg->buf, msg->len, GFP_KERNEL);
}
EXPORT_SYMBOL_GPL(i2c_get_dma_safe_msg_buf);
/**
* i2c_put_dma_safe_msg_buf - release DMA safe buffer and sync with i2c_msg
* @buf: the buffer obtained from i2c_get_dma_safe_msg_buf(). May be NULL.
* @msg: the message which the buffer corresponds to
* @xferred: bool saying if the message was transferred
*/
void i2c_put_dma_safe_msg_buf(u8 *buf, struct i2c_msg *msg, bool xferred)
{
if (!buf || buf == msg->buf)
return;
if (xferred && msg->flags & I2C_M_RD)
memcpy(msg->buf, buf, msg->len);
kfree(buf);
}
EXPORT_SYMBOL_GPL(i2c_put_dma_safe_msg_buf);
MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
MODULE_DESCRIPTION("I2C-Bus main module");
MODULE_LICENSE("GPL");
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