2021-01-25 00:41:23 +03:00
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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* The Netronix embedded controller is a microcontroller found in some
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* e-book readers designed by the original design manufacturer Netronix, Inc.
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* It contains RTC, battery monitoring, system power management, and PWM
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* functionality.
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*
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* This driver implements register access, version detection, and system
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* power-off/reset.
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*
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* Copyright 2020 Jonathan Neuschäfer <j.neuschaefer@gmx.net>
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*/
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#include <linux/delay.h>
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#include <linux/errno.h>
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#include <linux/i2c.h>
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#include <linux/mfd/core.h>
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#include <linux/mfd/ntxec.h>
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#include <linux/module.h>
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#include <linux/pm.h>
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#include <linux/reboot.h>
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#include <linux/regmap.h>
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#include <linux/types.h>
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#include <asm/unaligned.h>
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#define NTXEC_REG_VERSION 0x00
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#define NTXEC_REG_POWEROFF 0x50
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#define NTXEC_REG_POWERKEEP 0x70
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#define NTXEC_REG_RESET 0x90
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#define NTXEC_POWEROFF_VALUE 0x0100
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#define NTXEC_POWERKEEP_VALUE 0x0800
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#define NTXEC_RESET_VALUE 0xff00
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static struct i2c_client *poweroff_restart_client;
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static void ntxec_poweroff(void)
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{
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int res;
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u8 buf[3] = { NTXEC_REG_POWEROFF };
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struct i2c_msg msgs[] = {
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{
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.addr = poweroff_restart_client->addr,
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.flags = 0,
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.len = sizeof(buf),
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.buf = buf,
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},
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};
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put_unaligned_be16(NTXEC_POWEROFF_VALUE, buf + 1);
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res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs));
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if (res < 0)
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dev_warn(&poweroff_restart_client->dev,
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"Failed to power off (err = %d)\n", res);
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/*
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* The time from the register write until the host CPU is powered off
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* has been observed to be about 2.5 to 3 seconds. Sleep long enough to
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* safely avoid returning from the poweroff handler.
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*/
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msleep(5000);
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}
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static int ntxec_restart(struct notifier_block *nb,
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unsigned long action, void *data)
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{
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int res;
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u8 buf[3] = { NTXEC_REG_RESET };
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/*
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* NOTE: The lower half of the reset value is not sent, because sending
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* it causes an I2C error. (The reset handler in the downstream driver
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* does send the full two-byte value, but doesn't check the result).
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*/
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struct i2c_msg msgs[] = {
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{
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.addr = poweroff_restart_client->addr,
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.flags = 0,
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.len = sizeof(buf) - 1,
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.buf = buf,
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},
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};
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put_unaligned_be16(NTXEC_RESET_VALUE, buf + 1);
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res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs));
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if (res < 0)
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dev_warn(&poweroff_restart_client->dev,
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"Failed to restart (err = %d)\n", res);
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return NOTIFY_DONE;
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}
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static struct notifier_block ntxec_restart_handler = {
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.notifier_call = ntxec_restart,
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.priority = 128,
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};
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2021-03-15 22:18:32 +03:00
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static int regmap_ignore_write(void *context,
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unsigned int reg, unsigned int val)
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{
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struct regmap *regmap = context;
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regmap_write(regmap, reg, val);
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return 0;
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}
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static int regmap_wrap_read(void *context, unsigned int reg,
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unsigned int *val)
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{
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struct regmap *regmap = context;
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return regmap_read(regmap, reg, val);
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}
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/*
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* Some firmware versions do not ack written data, add a wrapper. It
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* is used to stack another regmap on top.
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*/
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static const struct regmap_config regmap_config_noack = {
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.name = "ntxec_noack",
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.reg_bits = 8,
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.val_bits = 16,
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.cache_type = REGCACHE_NONE,
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.reg_write = regmap_ignore_write,
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.reg_read = regmap_wrap_read
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};
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2021-01-25 00:41:23 +03:00
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static const struct regmap_config regmap_config = {
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.name = "ntxec",
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.reg_bits = 8,
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.val_bits = 16,
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.cache_type = REGCACHE_NONE,
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.val_format_endian = REGMAP_ENDIAN_BIG,
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};
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2021-03-15 22:18:32 +03:00
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static const struct mfd_cell ntxec_subdev[] = {
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2021-01-25 00:41:23 +03:00
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{ .name = "ntxec-rtc" },
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{ .name = "ntxec-pwm" },
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};
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2021-03-15 22:18:32 +03:00
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static const struct mfd_cell ntxec_subdev_pwm[] = {
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{ .name = "ntxec-pwm" },
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};
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2021-01-25 00:41:23 +03:00
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static int ntxec_probe(struct i2c_client *client)
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{
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struct ntxec *ec;
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unsigned int version;
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int res;
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2021-03-15 22:18:32 +03:00
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const struct mfd_cell *subdevs;
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size_t n_subdevs;
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2021-01-25 00:41:23 +03:00
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ec = devm_kmalloc(&client->dev, sizeof(*ec), GFP_KERNEL);
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if (!ec)
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return -ENOMEM;
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ec->dev = &client->dev;
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ec->regmap = devm_regmap_init_i2c(client, ®map_config);
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if (IS_ERR(ec->regmap)) {
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dev_err(ec->dev, "Failed to set up regmap for device\n");
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return PTR_ERR(ec->regmap);
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}
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/* Determine the firmware version */
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res = regmap_read(ec->regmap, NTXEC_REG_VERSION, &version);
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if (res < 0) {
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dev_err(ec->dev, "Failed to read firmware version number\n");
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return res;
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}
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/* Bail out if we encounter an unknown firmware version */
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switch (version) {
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case NTXEC_VERSION_KOBO_AURA:
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2021-03-15 22:18:32 +03:00
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subdevs = ntxec_subdev;
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n_subdevs = ARRAY_SIZE(ntxec_subdev);
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break;
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case NTXEC_VERSION_TOLINO_SHINE2:
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subdevs = ntxec_subdev_pwm;
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n_subdevs = ARRAY_SIZE(ntxec_subdev_pwm);
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/* Another regmap stacked on top of the other */
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ec->regmap = devm_regmap_init(ec->dev, NULL,
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ec->regmap,
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®map_config_noack);
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if (IS_ERR(ec->regmap))
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return PTR_ERR(ec->regmap);
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2021-01-25 00:41:23 +03:00
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break;
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default:
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dev_err(ec->dev,
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"Netronix embedded controller version %04x is not supported.\n",
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version);
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return -ENODEV;
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}
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dev_info(ec->dev,
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"Netronix embedded controller version %04x detected.\n", version);
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if (of_device_is_system_power_controller(ec->dev->of_node)) {
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/*
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* Set the 'powerkeep' bit. This is necessary on some boards
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* in order to keep the system running.
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*/
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res = regmap_write(ec->regmap, NTXEC_REG_POWERKEEP,
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NTXEC_POWERKEEP_VALUE);
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if (res < 0)
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return res;
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if (poweroff_restart_client)
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/*
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* Another instance of the driver already took
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* poweroff/restart duties.
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*/
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dev_err(ec->dev, "poweroff_restart_client already assigned\n");
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else
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poweroff_restart_client = client;
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if (pm_power_off)
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/* Another driver already registered a poweroff handler. */
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dev_err(ec->dev, "pm_power_off already assigned\n");
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else
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pm_power_off = ntxec_poweroff;
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res = register_restart_handler(&ntxec_restart_handler);
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if (res)
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dev_err(ec->dev,
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"Failed to register restart handler: %d\n", res);
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}
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i2c_set_clientdata(client, ec);
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2021-03-15 22:18:32 +03:00
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res = devm_mfd_add_devices(ec->dev, PLATFORM_DEVID_NONE,
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subdevs, n_subdevs, NULL, 0, NULL);
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2021-01-25 00:41:23 +03:00
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if (res)
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dev_err(ec->dev, "Failed to add subdevices: %d\n", res);
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return res;
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}
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2022-08-15 11:02:30 +03:00
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static void ntxec_remove(struct i2c_client *client)
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2021-01-25 00:41:23 +03:00
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{
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if (client == poweroff_restart_client) {
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poweroff_restart_client = NULL;
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pm_power_off = NULL;
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unregister_restart_handler(&ntxec_restart_handler);
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}
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}
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static const struct of_device_id of_ntxec_match_table[] = {
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{ .compatible = "netronix,ntxec", },
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{}
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};
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MODULE_DEVICE_TABLE(of, of_ntxec_match_table);
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static struct i2c_driver ntxec_driver = {
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.driver = {
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.name = "ntxec",
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.of_match_table = of_ntxec_match_table,
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},
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.probe_new = ntxec_probe,
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.remove = ntxec_remove,
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};
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module_i2c_driver(ntxec_driver);
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MODULE_AUTHOR("Jonathan Neuschäfer <j.neuschaefer@gmx.net>");
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MODULE_DESCRIPTION("Core driver for Netronix EC");
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MODULE_LICENSE("GPL");
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