// 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 <[email protected]>
*/
#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 <linux/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:
case NTXEC_VERSION_TOLINO_VISION:
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 = ntxec_probe,
.remove = ntxec_remove,
};
module_i2c_driver(ntxec_driver);
MODULE_AUTHOR("Jonathan Neuschäfer <[email protected]>");
MODULE_DESCRIPTION("Core driver for Netronix EC");
MODULE_LICENSE("GPL");
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