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 and version detection. Third-party hardware documentation is available at: https://github.com/neuschaefer/linux/wiki/Netronix-MSP430-embedded-controller The EC supports interrupts, but the driver doesn't make use of them so far. Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@xxxxxxx> Acked-for-MFD-by: Lee Jones <lee.jones@xxxxxxxxxx> --- v9: - Fix return value after regmap failure (bug found by kernel test robot <lkp@xxxxxxxxx>) v8: - https://lore.kernel.org/lkml/20210116194826.3866540-4-j.neuschaefer@xxxxxxx/ - Add missing MODULE_DEVICE_TABLE - Add module metadata (author, description, license) v7: - Add #define for version number (suggested by Lee Jones). v6: - Add Lee Jones' ACK v5: - no changes v4: - include asm/unaligned.h after linux/* - Use put_unaligned_be16 instead of open-coded big-endian packing - Clarify that 0x90=0xff00 causes an error in downstream kernel too - Add commas after non-sentinel positions - ntxec.h: declare structs device and regmap - Replace WARN_ON usage and add comments to explain errors - Replace dev_alert with dev_warn when the result isn't handled - Change subdevice registration error message to dev_err - Declare ntxec_reg8 as returning __be16 - Restructure version detection code - Spell out ODM v3: - Add (EC) to CONFIG_MFD_NTXEC prompt - Relicense as GPLv2 or later - Add email address to copyright line - remove empty lines in ntxec_poweroff and ntxec_restart functions - Split long lines - Remove 'Install ... handler' comments - Make naming of struct i2c_client parameter consistent - Remove struct ntxec_info - Rework 'depends on' lines in Kconfig, hard-depend on I2C, select REGMAP_I2C and MFD_CORE - Register subdevices via mfd_cells - Move 8-bit register conversion to ntxec.h v2: - Add a description of the device to the patch text - Unify spelling as 'Netronix embedded controller'. 'Netronix' is the proper name of the manufacturer, but 'embedded controller' is just a label that I have assigned to the device. - Switch to regmap, avoid regmap use in poweroff and reboot handlers. Inspired by cf84dc0bb40f4 ("mfd: rn5t618: Make restart handler atomic safe") - Use a list of known-working firmware versions instead of checking for a known-incompatible version - Prefix registers with NTXEC_REG_ - Define register values as constants - Various style cleanups as suggested by Lee Jones - Don't align = signs in struct initializers [Uwe Kleine-König] - Don't use dev_dbg for an error message - Explain sleep in poweroff handler - Remove (struct ntxec).client - Switch to .probe_new in i2c driver - Add .remove callback - Make CONFIG_MFD_NTXEC a tristate option --- drivers/mfd/Kconfig | 11 ++ drivers/mfd/Makefile | 1 + drivers/mfd/ntxec.c | 221 ++++++++++++++++++++++++++++++++++++++ include/linux/mfd/ntxec.h | 37 +++++++ 4 files changed, 270 insertions(+) create mode 100644 drivers/mfd/ntxec.c create mode 100644 include/linux/mfd/ntxec.h diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig index bdfce7b156216..4280bcd47ec7d 100644 --- a/drivers/mfd/Kconfig +++ b/drivers/mfd/Kconfig @@ -976,6 +976,17 @@ config MFD_VIPERBOARD You need to select the mfd cell drivers separately. The drivers do not support all features the board exposes. +config MFD_NTXEC + tristate "Netronix embedded controller (EC)" + depends on OF || COMPILE_TEST + depends on I2C + select REGMAP_I2C + select MFD_CORE + help + Say yes here if you want to support the embedded controller found in + certain e-book readers designed by the original design manufacturer + Netronix. + config MFD_RETU tristate "Nokia Retu and Tahvo multi-function device" select MFD_CORE diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile index 14fdb188af022..948a3bf8e3e57 100644 --- a/drivers/mfd/Makefile +++ b/drivers/mfd/Makefile @@ -219,6 +219,7 @@ obj-$(CONFIG_MFD_INTEL_PMC_BXT) += intel_pmc_bxt.o obj-$(CONFIG_MFD_INTEL_PMT) += intel_pmt.o obj-$(CONFIG_MFD_PALMAS) += palmas.o obj-$(CONFIG_MFD_VIPERBOARD) += viperboard.o +obj-$(CONFIG_MFD_NTXEC) += ntxec.o obj-$(CONFIG_MFD_RC5T583) += rc5t583.o rc5t583-irq.o obj-$(CONFIG_MFD_RK808) += rk808.o obj-$(CONFIG_MFD_RN5T618) += rn5t618.o diff --git a/drivers/mfd/ntxec.c b/drivers/mfd/ntxec.c new file mode 100644 index 0000000000000..957de2b035290 --- /dev/null +++ b/drivers/mfd/ntxec.c @@ -0,0 +1,221 @@ +// 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@xxxxxxx> + */ + +#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 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_subdevices[] = { + { .name = "ntxec-rtc" }, + { .name = "ntxec-pwm" }, +}; + +static int ntxec_probe(struct i2c_client *client) +{ + struct ntxec *ec; + unsigned int version; + int res; + + 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: + 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, ntxec_subdevices, + ARRAY_SIZE(ntxec_subdevices), NULL, 0, NULL); + if (res) + dev_err(ec->dev, "Failed to add subdevices: %d\n", res); + + return res; +} + +static int 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); + } + + return 0; +} + +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@xxxxxxx>"); +MODULE_DESCRIPTION("Core driver for Netronix EC"); +MODULE_LICENSE("GPL"); diff --git a/include/linux/mfd/ntxec.h b/include/linux/mfd/ntxec.h new file mode 100644 index 0000000000000..361204d125f1a --- /dev/null +++ b/include/linux/mfd/ntxec.h @@ -0,0 +1,37 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright 2020 Jonathan Neuschäfer + * + * Register access and version information for the Netronix embedded + * controller. + */ + +#ifndef NTXEC_H +#define NTXEC_H + +#include <linux/types.h> + +struct device; +struct regmap; + +struct ntxec { + struct device *dev; + struct regmap *regmap; +}; + +/* + * Some registers, such as the battery status register (0x41), are in + * big-endian, but others only have eight significant bits, which are in the + * first byte transmitted over I2C (the MSB of the big-endian value). + * This convenience function converts an 8-bit value to 16-bit for use in the + * second kind of register. + */ +static inline __be16 ntxec_reg8(u8 value) +{ + return value << 8; +} + +/* Known firmware versions */ +#define NTXEC_VERSION_KOBO_AURA 0xd726 /* found in Kobo Aura */ + +#endif -- 2.29.2
