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// SPDX-License-Identifier: BSD-2-Clause OR GPL-2.0-or-later
/*
* ENE KB3930 Embedded Controller Driver
*
* Copyright (C) 2020 Lubomir Rintel
*/
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/mfd/core.h>
#include <linux/module.h>
#include <linux/reboot.h>
#include <linux/regmap.h>
/* I2C registers that are multiplexing access to the EC RAM. */
enum {
EC_DATA_IN = 0x00,
EC_RAM_OUT = 0x80,
EC_RAM_IN = 0x81,
};
/* EC RAM registers. */
enum {
EC_MODEL = 0x30,
EC_VERSION_MAJ = 0x31,
EC_VERSION_MIN = 0x32,
};
struct kb3930 {
struct i2c_client *client;
struct regmap *ram_regmap;
struct gpio_descs *off_gpios;
};
static struct kb3930 *kb3930_power_off;
#define EC_GPIO_WAVE 0
#define EC_GPIO_OFF_MODE 1
#define EC_OFF_MODE_REBOOT 0
#define EC_OFF_MODE_POWER 1
static void kb3930_off(struct kb3930 *ddata, int off_mode)
{
gpiod_direction_output(ddata->off_gpios->desc[EC_GPIO_OFF_MODE],
off_mode);
/*
* This creates a 10 Hz wave on EC_GPIO_WAVE that signals a
* shutdown request to the EC. Once the EC detects it, it will
* proceed to turn the power off or reset the board depending on
* the value of EC_GPIO_OFF_MODE.
*/
while (1) {
mdelay(50);
gpiod_direction_output(ddata->off_gpios->desc[EC_GPIO_WAVE], 0);
mdelay(50);
gpiod_direction_output(ddata->off_gpios->desc[EC_GPIO_WAVE], 1);
}
}
static int kb3930_restart(struct notifier_block *this,
unsigned long mode, void *cmd)
{
kb3930_off(kb3930_power_off, EC_OFF_MODE_REBOOT);
return NOTIFY_DONE;
}
static void kb3930_pm_power_off(void)
{
kb3930_off(kb3930_power_off, EC_OFF_MODE_POWER);
}
static struct notifier_block kb3930_restart_nb = {
.notifier_call = kb3930_restart,
};
static const struct mfd_cell ariel_ec_cells[] = {
{ .name = "dell-wyse-ariel-led", },
{ .name = "dell-wyse-ariel-power", },
};
static int kb3930_ec_ram_reg_write(void *context, unsigned int reg,
unsigned int val)
{
struct kb3930 *ddata = context;
return i2c_smbus_write_word_data(ddata->client, EC_RAM_OUT,
(val << 8) | reg);
}
static int kb3930_ec_ram_reg_read(void *context, unsigned int reg,
unsigned int *val)
{
struct kb3930 *ddata = context;
int ret;
ret = i2c_smbus_write_word_data(ddata->client, EC_RAM_IN, reg);
if (ret < 0)
return ret;
ret = i2c_smbus_read_word_data(ddata->client, EC_DATA_IN);
if (ret < 0)
return ret;
*val = ret >> 8;
return 0;
}
static const struct regmap_config kb3930_ram_regmap_config = {
.name = "ec_ram",
.reg_bits = 8,
.val_bits = 8,
.reg_stride = 1,
.max_register = 0xff,
.reg_write = kb3930_ec_ram_reg_write,
.reg_read = kb3930_ec_ram_reg_read,
.fast_io = false,
};
static int kb3930_probe(struct i2c_client *client)
{
struct device *dev = &client->dev;
struct device_node *np = dev->of_node;
struct kb3930 *ddata;
unsigned int model;
int ret;
ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
if (!ddata)
return -ENOMEM;
kb3930_power_off = ddata;
ddata->client = client;
i2c_set_clientdata(client, ddata);
ddata->ram_regmap = devm_regmap_init(dev, NULL, ddata,
&kb3930_ram_regmap_config);
if (IS_ERR(ddata->ram_regmap))
return PTR_ERR(ddata->ram_regmap);
ret = regmap_read(ddata->ram_regmap, EC_MODEL, &model);
if (ret < 0)
return ret;
/* Currently we only support the cells present on Dell Ariel model. */
if (model != 'J') {
dev_err(dev, "unknown board model: %02x\n", model);
return -ENODEV;
}
ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_AUTO,
ariel_ec_cells,
ARRAY_SIZE(ariel_ec_cells),
NULL, 0, NULL);
if (ret)
return ret;
if (of_property_read_bool(np, "system-power-controller")) {
ddata->off_gpios =
devm_gpiod_get_array_optional(dev, "off", GPIOD_IN);
if (IS_ERR(ddata->off_gpios))
return PTR_ERR(ddata->off_gpios);
if (ddata->off_gpios->ndescs < 2) {
dev_err(dev, "invalid off-gpios property\n");
return -EINVAL;
}
}
if (ddata->off_gpios) {
register_restart_handler(&kb3930_restart_nb);
if (!pm_power_off)
pm_power_off = kb3930_pm_power_off;
}
return 0;
}
static void kb3930_remove(struct i2c_client *client)
{
struct kb3930 *ddata = i2c_get_clientdata(client);
if (ddata->off_gpios) {
if (pm_power_off == kb3930_pm_power_off)
pm_power_off = NULL;
unregister_restart_handler(&kb3930_restart_nb);
}
kb3930_power_off = NULL;
}
static const struct of_device_id kb3930_dt_ids[] = {
{ .compatible = "ene,kb3930" },
{ }
};
MODULE_DEVICE_TABLE(of, kb3930_dt_ids);
static struct i2c_driver kb3930_driver = {
.probe_new = kb3930_probe,
.remove = kb3930_remove,
.driver = {
.name = "ene-kb3930",
.of_match_table = kb3930_dt_ids,
},
};
module_i2c_driver(kb3930_driver);
MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
MODULE_DESCRIPTION("ENE KB3930 Embedded Controller Driver");
MODULE_LICENSE("Dual BSD/GPL");
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