WSL2-Linux-Kernel/drivers/w1/slaves/w1_ds2780.c

164 строки
3.6 KiB
C
Исходник Обычный вид История

/*
* 1-Wire implementation for the ds2780 chip
*
* Copyright (C) 2010 Indesign, LLC
*
* Author: Clifton Barnes <cabarnes@indesign-llc.com>
*
* Based on w1-ds2760 driver
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/platform_device.h>
#include <linux/mutex.h>
#include <linux/idr.h>
#include <linux/w1.h>
#include "w1_ds2780.h"
#define W1_FAMILY_DS2780 0x32
static int w1_ds2780_do_io(struct device *dev, char *buf, int addr,
size_t count, int io)
{
struct w1_slave *sl = container_of(dev, struct w1_slave, dev);
if (addr > DS2780_DATA_SIZE || addr < 0)
return 0;
count = min_t(int, count, DS2780_DATA_SIZE - addr);
if (w1_reset_select_slave(sl) == 0) {
if (io) {
w1_write_8(sl->master, W1_DS2780_WRITE_DATA);
w1_write_8(sl->master, addr);
w1_write_block(sl->master, buf, count);
} else {
w1_write_8(sl->master, W1_DS2780_READ_DATA);
w1_write_8(sl->master, addr);
count = w1_read_block(sl->master, buf, count);
}
}
return count;
}
int w1_ds2780_io(struct device *dev, char *buf, int addr, size_t count,
int io)
{
struct w1_slave *sl = container_of(dev, struct w1_slave, dev);
int ret;
if (!dev)
return -ENODEV;
W1: split master mutex to avoid deadlocks. The 'mutex' in struct w1_master is use for two very different purposes. Firstly it protects various data structures such as the list of all slaves. Secondly it protects the w1 buss against concurrent accesses. This can lead to deadlocks when the ->probe code called while adding a slave needs to talk on the bus, as is the case for power_supply devices. ds2780 and ds2781 drivers contain a work around to track which process hold the lock simply to avoid this deadlock. bq27000 doesn't have that work around and so deadlocks. There are other possible deadlocks involving sysfs. When removing a device the sysfs s_active lock is held, so the lock that protects the slave list must take precedence over s_active. However when access power_supply attributes via sysfs, the s_active lock must take precedence over the lock that protects accesses to the bus. So to avoid deadlocks between w1 slaves and sysfs, these must be two separate locks. Making them separate means that the work around in ds2780 and ds2781 can be removed. So this patch: - adds a new mutex: "bus_mutex" which serialises access to the bus. - takes in mutex in w1_search and ds1wm_search while they access the bus for searching. The mutex is dropped before calling the callback which adds the slave. - changes all slaves to use bus_mutex instead of mutex to protect access to the bus - removes w1_ds2790_io_nolock and w1_ds2781_io_nolock, and the related code from drivers/power/ds278[01]_battery.c which calls them. Signed-off-by: NeilBrown <neilb@suse.de> Acked-by: Evgeniy Polyakov <zbr@ioremap.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-05-18 09:59:52 +04:00
mutex_lock(&sl->master->bus_mutex);
ret = w1_ds2780_do_io(dev, buf, addr, count, io);
W1: split master mutex to avoid deadlocks. The 'mutex' in struct w1_master is use for two very different purposes. Firstly it protects various data structures such as the list of all slaves. Secondly it protects the w1 buss against concurrent accesses. This can lead to deadlocks when the ->probe code called while adding a slave needs to talk on the bus, as is the case for power_supply devices. ds2780 and ds2781 drivers contain a work around to track which process hold the lock simply to avoid this deadlock. bq27000 doesn't have that work around and so deadlocks. There are other possible deadlocks involving sysfs. When removing a device the sysfs s_active lock is held, so the lock that protects the slave list must take precedence over s_active. However when access power_supply attributes via sysfs, the s_active lock must take precedence over the lock that protects accesses to the bus. So to avoid deadlocks between w1 slaves and sysfs, these must be two separate locks. Making them separate means that the work around in ds2780 and ds2781 can be removed. So this patch: - adds a new mutex: "bus_mutex" which serialises access to the bus. - takes in mutex in w1_search and ds1wm_search while they access the bus for searching. The mutex is dropped before calling the callback which adds the slave. - changes all slaves to use bus_mutex instead of mutex to protect access to the bus - removes w1_ds2790_io_nolock and w1_ds2781_io_nolock, and the related code from drivers/power/ds278[01]_battery.c which calls them. Signed-off-by: NeilBrown <neilb@suse.de> Acked-by: Evgeniy Polyakov <zbr@ioremap.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-05-18 09:59:52 +04:00
mutex_unlock(&sl->master->bus_mutex);
return ret;
}
EXPORT_SYMBOL(w1_ds2780_io);
int w1_ds2780_eeprom_cmd(struct device *dev, int addr, int cmd)
{
struct w1_slave *sl = container_of(dev, struct w1_slave, dev);
if (!dev)
return -EINVAL;
W1: split master mutex to avoid deadlocks. The 'mutex' in struct w1_master is use for two very different purposes. Firstly it protects various data structures such as the list of all slaves. Secondly it protects the w1 buss against concurrent accesses. This can lead to deadlocks when the ->probe code called while adding a slave needs to talk on the bus, as is the case for power_supply devices. ds2780 and ds2781 drivers contain a work around to track which process hold the lock simply to avoid this deadlock. bq27000 doesn't have that work around and so deadlocks. There are other possible deadlocks involving sysfs. When removing a device the sysfs s_active lock is held, so the lock that protects the slave list must take precedence over s_active. However when access power_supply attributes via sysfs, the s_active lock must take precedence over the lock that protects accesses to the bus. So to avoid deadlocks between w1 slaves and sysfs, these must be two separate locks. Making them separate means that the work around in ds2780 and ds2781 can be removed. So this patch: - adds a new mutex: "bus_mutex" which serialises access to the bus. - takes in mutex in w1_search and ds1wm_search while they access the bus for searching. The mutex is dropped before calling the callback which adds the slave. - changes all slaves to use bus_mutex instead of mutex to protect access to the bus - removes w1_ds2790_io_nolock and w1_ds2781_io_nolock, and the related code from drivers/power/ds278[01]_battery.c which calls them. Signed-off-by: NeilBrown <neilb@suse.de> Acked-by: Evgeniy Polyakov <zbr@ioremap.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-05-18 09:59:52 +04:00
mutex_lock(&sl->master->bus_mutex);
if (w1_reset_select_slave(sl) == 0) {
w1_write_8(sl->master, cmd);
w1_write_8(sl->master, addr);
}
W1: split master mutex to avoid deadlocks. The 'mutex' in struct w1_master is use for two very different purposes. Firstly it protects various data structures such as the list of all slaves. Secondly it protects the w1 buss against concurrent accesses. This can lead to deadlocks when the ->probe code called while adding a slave needs to talk on the bus, as is the case for power_supply devices. ds2780 and ds2781 drivers contain a work around to track which process hold the lock simply to avoid this deadlock. bq27000 doesn't have that work around and so deadlocks. There are other possible deadlocks involving sysfs. When removing a device the sysfs s_active lock is held, so the lock that protects the slave list must take precedence over s_active. However when access power_supply attributes via sysfs, the s_active lock must take precedence over the lock that protects accesses to the bus. So to avoid deadlocks between w1 slaves and sysfs, these must be two separate locks. Making them separate means that the work around in ds2780 and ds2781 can be removed. So this patch: - adds a new mutex: "bus_mutex" which serialises access to the bus. - takes in mutex in w1_search and ds1wm_search while they access the bus for searching. The mutex is dropped before calling the callback which adds the slave. - changes all slaves to use bus_mutex instead of mutex to protect access to the bus - removes w1_ds2790_io_nolock and w1_ds2781_io_nolock, and the related code from drivers/power/ds278[01]_battery.c which calls them. Signed-off-by: NeilBrown <neilb@suse.de> Acked-by: Evgeniy Polyakov <zbr@ioremap.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-05-18 09:59:52 +04:00
mutex_unlock(&sl->master->bus_mutex);
return 0;
}
EXPORT_SYMBOL(w1_ds2780_eeprom_cmd);
static ssize_t w1_slave_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *bin_attr, char *buf,
loff_t off, size_t count)
{
struct device *dev = container_of(kobj, struct device, kobj);
return w1_ds2780_io(dev, buf, off, count, 0);
}
static BIN_ATTR_RO(w1_slave, DS2780_DATA_SIZE);
static struct bin_attribute *w1_ds2780_bin_attrs[] = {
&bin_attr_w1_slave,
NULL,
};
static const struct attribute_group w1_ds2780_group = {
.bin_attrs = w1_ds2780_bin_attrs,
};
static const struct attribute_group *w1_ds2780_groups[] = {
&w1_ds2780_group,
NULL,
};
static int w1_ds2780_add_slave(struct w1_slave *sl)
{
int ret;
struct platform_device *pdev;
pdev = platform_device_alloc("ds2780-battery", PLATFORM_DEVID_AUTO);
if (!pdev)
return -ENOMEM;
pdev->dev.parent = &sl->dev;
ret = platform_device_add(pdev);
if (ret)
goto pdev_add_failed;
dev_set_drvdata(&sl->dev, pdev);
return 0;
pdev_add_failed:
platform_device_put(pdev);
return ret;
}
static void w1_ds2780_remove_slave(struct w1_slave *sl)
{
struct platform_device *pdev = dev_get_drvdata(&sl->dev);
platform_device_unregister(pdev);
}
static struct w1_family_ops w1_ds2780_fops = {
.add_slave = w1_ds2780_add_slave,
.remove_slave = w1_ds2780_remove_slave,
.groups = w1_ds2780_groups,
};
static struct w1_family w1_ds2780_family = {
.fid = W1_FAMILY_DS2780,
.fops = &w1_ds2780_fops,
};
module_w1_family(w1_ds2780_family);
MODULE_AUTHOR("Clifton Barnes <cabarnes@indesign-llc.com>");
MODULE_DESCRIPTION("1-wire Driver for Maxim/Dallas DS2780 Stand-Alone Fuel Gauge IC");
MODULE_LICENSE("GPL");
MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS2780));