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. Known problems: - The reboot handler is installed in such a way that it directly calls into the i2c subsystem to send the reboot command to the EC. This means that the reboot handler may sleep, which is not allowed. Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@xxxxxxx> --- drivers/mfd/Kconfig | 7 ++ drivers/mfd/Makefile | 1 + drivers/mfd/ntxec.c | 188 ++++++++++++++++++++++++++++++++++++++ include/linux/mfd/ntxec.h | 30 ++++++ 4 files changed, 226 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 a37d7d1713820..78410b928648e 100644 --- a/drivers/mfd/Kconfig +++ b/drivers/mfd/Kconfig @@ -978,6 +978,13 @@ 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 + bool "Netronix Embedded Controller" + depends on I2C && OF + help + Say yes here if you want to support the embedded controller of + certain e-book readers designed by the ODM 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 9367a92f795a6..19d9391ed6f32 100644 --- a/drivers/mfd/Makefile +++ b/drivers/mfd/Makefile @@ -218,6 +218,7 @@ obj-$(CONFIG_MFD_INTEL_MSIC) += intel_msic.o obj-$(CONFIG_MFD_INTEL_PMC_BXT) += intel_pmc_bxt.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..82adea34ea746 --- /dev/null +++ b/drivers/mfd/ntxec.c @@ -0,0 +1,188 @@ +// SPDX-License-Identifier: GPL-2.0-only +// Copyright 2020 Jonathan Neuschäfer +// +// MFD driver for the usually MSP430-based embedded controller used in certain +// Netronix ebook reader board designs + +#include <asm/unaligned.h> +#include <linux/delay.h> +#include <linux/errno.h> +#include <linux/i2c.h> +#include <linux/mfd/ntxec.h> +#include <linux/of_platform.h> +#include <linux/pm.h> +#include <linux/reboot.h> +#include <linux/types.h> + + +#define NTXEC_VERSION 0x00 +#define NTXEC_POWEROFF 0x50 +#define NTXEC_POWERKEEP 0x70 +#define NTXEC_RESET 0x90 + + +/* Register access */ + +int ntxec_read16(struct ntxec *ec, u8 addr) +{ + u8 request[1] = { addr }; + u8 response[2]; + int res; + + struct i2c_msg msgs[] = { + { + .addr = ec->client->addr, + .flags = ec->client->flags, + .len = sizeof(request), + .buf = request + }, { + .addr = ec->client->addr, + .flags = ec->client->flags | I2C_M_RD, + .len = sizeof(response), + .buf = response + } + }; + + res = i2c_transfer(ec->client->adapter, msgs, ARRAY_SIZE(msgs)); + if (res < 0) + return res; + if (res != ARRAY_SIZE(msgs)) + return -EIO; + + return get_unaligned_be16(response); +} +EXPORT_SYMBOL(ntxec_read16); + +int ntxec_write16(struct ntxec *ec, u8 addr, u16 value) +{ + u8 request[3] = { addr, }; + int res; + + put_unaligned_be16(value, request + 1); + + res = i2c_transfer_buffer_flags(ec->client, request, sizeof(request), + ec->client->flags); + if (res < 0) + return res; + + return 0; +} +EXPORT_SYMBOL(ntxec_write16); + +int ntxec_read8(struct ntxec *ec, u8 addr) +{ + int res = ntxec_read16(ec, addr); + + if (res < 0) + return res; + + return (res >> 8) & 0xff; +} +EXPORT_SYMBOL(ntxec_read8); + +int ntxec_write8(struct ntxec *ec, u8 addr, u8 value) +{ + return ntxec_write16(ec, addr, value << 8); +} +EXPORT_SYMBOL(ntxec_write8); + + +/* Reboot/poweroff handling */ + +static struct ntxec *poweroff_restart_instance; + +static void ntxec_poweroff(void) +{ + ntxec_write8(poweroff_restart_instance, NTXEC_POWEROFF, 0x01); + msleep(5000); +} + +static int ntxec_restart(struct notifier_block *nb, + unsigned long action, void *data) +{ + /* FIXME: The I2C driver sleeps, but restart handlers may not sleep */ + ntxec_write8(poweroff_restart_instance, NTXEC_RESET, 0xff); + /* TODO: delay? */ + return NOTIFY_DONE; +} + +static struct notifier_block ntxec_restart_handler = { + .notifier_call = ntxec_restart, + .priority = 128 +}; + + +/* Driver setup */ + +static int ntxec_probe(struct i2c_client *client, + const struct i2c_device_id *ids) +{ + struct ntxec *ec; + int res; + + ec = devm_kmalloc(&client->dev, sizeof(*ec), GFP_KERNEL); + if (!ec) + return -ENOMEM; + + ec->dev = &client->dev; + ec->client = client; + + /* Determine the firmware version */ + res = ntxec_read16(ec, NTXEC_VERSION); + if (res < 0) { + dev_dbg(ec->dev, "Failed to read firmware version number\n"); + return res; + } + ec->version = res; + + dev_info(ec->dev, + "Netronix embedded controller version %04x detected.\n", + ec->version); + + /* For now, we don't support the new register layout. */ + if (ntxec_has_new_layout(ec)) + return -EOPNOTSUPP; + + 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 = ntxec_write8(ec, NTXEC_POWERKEEP, 0x08); + if (res < 0) + return res; + + /* Install poweroff handler */ + WARN_ON(poweroff_restart_instance); + poweroff_restart_instance = ec; + if (pm_power_off != NULL) + /* TODO: Refactor among all poweroff drivers */ + dev_err(ec->dev, "pm_power_off already assigned\n"); + else + pm_power_off = ntxec_poweroff; + + /* Install board reset handler */ + res = register_restart_handler(&ntxec_restart_handler); + if (res < 0) + dev_err(ec->dev, + "Failed to register restart handler: %d\n", res); + } + + i2c_set_clientdata(client, ec); + + return devm_of_platform_populate(ec->dev); +} + +static const struct of_device_id of_ntxec_match_table[] = { + { .compatible = "netronix,ntxec", }, + {} +}; + +static struct i2c_driver ntxec_driver = { + .driver = { + .name = "ntxec", + .of_match_table = of_ntxec_match_table, + }, + .probe = ntxec_probe, +}; +builtin_i2c_driver(ntxec_driver); diff --git a/include/linux/mfd/ntxec.h b/include/linux/mfd/ntxec.h new file mode 100644 index 0000000000000..9f9d6f2141751 --- /dev/null +++ b/include/linux/mfd/ntxec.h @@ -0,0 +1,30 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright 2020 Jonathan Neuschäfer + * + * MFD access functions for the Netronix embedded controller. + */ + +#ifndef NTXEC_H +#define NTXEC_H + +#include <linux/types.h> + +struct ntxec { + struct device *dev; + struct i2c_client *client; + u16 version; + /* TODO: Add a mutex to protect actions consisting of multiple accesses? */ +}; + +static inline bool ntxec_has_new_layout(struct ntxec *ec) +{ + return ec->version == 0xe916; +} + +int ntxec_read16(struct ntxec *ec, u8 addr); +int ntxec_write16(struct ntxec *ec, u8 addr, u16 value); +int ntxec_read8(struct ntxec *ec, u8 addr); +int ntxec_write8(struct ntxec *ec, u8 addr, u8 value); + +#endif -- 2.27.0
