diff options
Diffstat (limited to 'drivers/mfd/ntxec.c')
| -rw-r--r-- | drivers/mfd/ntxec.c | 269 |
1 files changed, 269 insertions, 0 deletions
diff --git a/drivers/mfd/ntxec.c b/drivers/mfd/ntxec.c new file mode 100644 index 000000000..e16a7a82a --- /dev/null +++ b/drivers/mfd/ntxec.c @@ -0,0 +1,269 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * The Netronix embedded controller is a microcontroller found in some + * e-book readers designed by the original design manufacturer Netronix, Inc. + * It contains RTC, battery monitoring, system power management, and PWM + * functionality. + * + * This driver implements register access, version detection, and system + * power-off/reset. + * + * Copyright 2020 Jonathan Neuschäfer <j.neuschaefer@gmx.net> + */ + +#include <linux/delay.h> +#include <linux/errno.h> +#include <linux/i2c.h> +#include <linux/mfd/core.h> +#include <linux/mfd/ntxec.h> +#include <linux/module.h> +#include <linux/pm.h> +#include <linux/reboot.h> +#include <linux/regmap.h> +#include <linux/types.h> +#include <asm/unaligned.h> + +#define NTXEC_REG_VERSION 0x00 +#define NTXEC_REG_POWEROFF 0x50 +#define NTXEC_REG_POWERKEEP 0x70 +#define NTXEC_REG_RESET 0x90 + +#define NTXEC_POWEROFF_VALUE 0x0100 +#define NTXEC_POWERKEEP_VALUE 0x0800 +#define NTXEC_RESET_VALUE 0xff00 + +static struct i2c_client *poweroff_restart_client; + +static void ntxec_poweroff(void) +{ + int res; + u8 buf[3] = { NTXEC_REG_POWEROFF }; + struct i2c_msg msgs[] = { + { + .addr = poweroff_restart_client->addr, + .flags = 0, + .len = sizeof(buf), + .buf = buf, + }, + }; + + put_unaligned_be16(NTXEC_POWEROFF_VALUE, buf + 1); + + res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs)); + if (res < 0) + dev_warn(&poweroff_restart_client->dev, + "Failed to power off (err = %d)\n", res); + + /* + * The time from the register write until the host CPU is powered off + * has been observed to be about 2.5 to 3 seconds. Sleep long enough to + * safely avoid returning from the poweroff handler. + */ + msleep(5000); +} + +static int ntxec_restart(struct notifier_block *nb, + unsigned long action, void *data) +{ + int res; + u8 buf[3] = { NTXEC_REG_RESET }; + /* + * NOTE: The lower half of the reset value is not sent, because sending + * it causes an I2C error. (The reset handler in the downstream driver + * does send the full two-byte value, but doesn't check the result). + */ + struct i2c_msg msgs[] = { + { + .addr = poweroff_restart_client->addr, + .flags = 0, + .len = sizeof(buf) - 1, + .buf = buf, + }, + }; + + put_unaligned_be16(NTXEC_RESET_VALUE, buf + 1); + + res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs)); + if (res < 0) + dev_warn(&poweroff_restart_client->dev, + "Failed to restart (err = %d)\n", res); + + return NOTIFY_DONE; +} + +static struct notifier_block ntxec_restart_handler = { + .notifier_call = ntxec_restart, + .priority = 128, +}; + +static int regmap_ignore_write(void *context, + unsigned int reg, unsigned int val) + +{ + struct regmap *regmap = context; + + regmap_write(regmap, reg, val); + + return 0; +} + +static int regmap_wrap_read(void *context, unsigned int reg, + unsigned int *val) +{ + struct regmap *regmap = context; + + return regmap_read(regmap, reg, val); +} + +/* + * Some firmware versions do not ack written data, add a wrapper. It + * is used to stack another regmap on top. + */ +static const struct regmap_config regmap_config_noack = { + .name = "ntxec_noack", + .reg_bits = 8, + .val_bits = 16, + .cache_type = REGCACHE_NONE, + .reg_write = regmap_ignore_write, + .reg_read = regmap_wrap_read +}; + +static const struct regmap_config regmap_config = { + .name = "ntxec", + .reg_bits = 8, + .val_bits = 16, + .cache_type = REGCACHE_NONE, + .val_format_endian = REGMAP_ENDIAN_BIG, +}; + +static const struct mfd_cell ntxec_subdev[] = { + { .name = "ntxec-rtc" }, + { .name = "ntxec-pwm" }, +}; + +static const struct mfd_cell ntxec_subdev_pwm[] = { + { .name = "ntxec-pwm" }, +}; + +static int ntxec_probe(struct i2c_client *client) +{ + struct ntxec *ec; + unsigned int version; + int res; + const struct mfd_cell *subdevs; + size_t n_subdevs; + + ec = devm_kmalloc(&client->dev, sizeof(*ec), GFP_KERNEL); + if (!ec) + return -ENOMEM; + + ec->dev = &client->dev; + + ec->regmap = devm_regmap_init_i2c(client, ®map_config); + if (IS_ERR(ec->regmap)) { + dev_err(ec->dev, "Failed to set up regmap for device\n"); + return PTR_ERR(ec->regmap); + } + + /* Determine the firmware version */ + res = regmap_read(ec->regmap, NTXEC_REG_VERSION, &version); + if (res < 0) { + dev_err(ec->dev, "Failed to read firmware version number\n"); + return res; + } + + /* Bail out if we encounter an unknown firmware version */ + switch (version) { + case NTXEC_VERSION_KOBO_AURA: + subdevs = ntxec_subdev; + n_subdevs = ARRAY_SIZE(ntxec_subdev); + break; + case NTXEC_VERSION_TOLINO_SHINE2: + subdevs = ntxec_subdev_pwm; + n_subdevs = ARRAY_SIZE(ntxec_subdev_pwm); + /* Another regmap stacked on top of the other */ + ec->regmap = devm_regmap_init(ec->dev, NULL, + ec->regmap, + ®map_config_noack); + if (IS_ERR(ec->regmap)) + return PTR_ERR(ec->regmap); + break; + default: + dev_err(ec->dev, + "Netronix embedded controller version %04x is not supported.\n", + version); + return -ENODEV; + } + + dev_info(ec->dev, + "Netronix embedded controller version %04x detected.\n", version); + + if (of_device_is_system_power_controller(ec->dev->of_node)) { + /* + * Set the 'powerkeep' bit. This is necessary on some boards + * in order to keep the system running. + */ + res = regmap_write(ec->regmap, NTXEC_REG_POWERKEEP, + NTXEC_POWERKEEP_VALUE); + if (res < 0) + return res; + + if (poweroff_restart_client) + /* + * Another instance of the driver already took + * poweroff/restart duties. + */ + dev_err(ec->dev, "poweroff_restart_client already assigned\n"); + else + poweroff_restart_client = client; + + if (pm_power_off) + /* Another driver already registered a poweroff handler. */ + dev_err(ec->dev, "pm_power_off already assigned\n"); + else + pm_power_off = ntxec_poweroff; + + res = register_restart_handler(&ntxec_restart_handler); + if (res) + dev_err(ec->dev, + "Failed to register restart handler: %d\n", res); + } + + i2c_set_clientdata(client, ec); + + res = devm_mfd_add_devices(ec->dev, PLATFORM_DEVID_NONE, + subdevs, n_subdevs, NULL, 0, NULL); + if (res) + dev_err(ec->dev, "Failed to add subdevices: %d\n", res); + + return res; +} + +static void ntxec_remove(struct i2c_client *client) +{ + if (client == poweroff_restart_client) { + poweroff_restart_client = NULL; + pm_power_off = NULL; + unregister_restart_handler(&ntxec_restart_handler); + } +} + +static const struct of_device_id of_ntxec_match_table[] = { + { .compatible = "netronix,ntxec", }, + {} +}; +MODULE_DEVICE_TABLE(of, of_ntxec_match_table); + +static struct i2c_driver ntxec_driver = { + .driver = { + .name = "ntxec", + .of_match_table = of_ntxec_match_table, + }, + .probe_new = ntxec_probe, + .remove = ntxec_remove, +}; +module_i2c_driver(ntxec_driver); + +MODULE_AUTHOR("Jonathan Neuschäfer <j.neuschaefer@gmx.net>"); +MODULE_DESCRIPTION("Core driver for Netronix EC"); +MODULE_LICENSE("GPL"); |