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271 lines
6.6 KiB
271 lines
6.6 KiB
// 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 <[email protected]> |
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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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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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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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static const struct mfd_cell ntxec_subdev[] = { |
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{ .name = "ntxec-rtc" }, |
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{ .name = "ntxec-pwm" }, |
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}; |
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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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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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const struct mfd_cell *subdevs; |
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size_t n_subdevs; |
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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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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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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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res = devm_mfd_add_devices(ec->dev, PLATFORM_DEVID_NONE, |
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subdevs, n_subdevs, NULL, 0, NULL); |
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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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static int ntxec_remove(struct i2c_client *client) |
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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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return 0; |
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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 <[email protected]>"); |
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MODULE_DESCRIPTION("Core driver for Netronix EC"); |
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MODULE_LICENSE("GPL");
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