1// SPDX-License-Identifier: GPL-2.0+
  2/*
  3 * Acer Iconia Tab A500 Embedded Controller Driver
  4 *
  5 * Copyright 2020 GRATE-driver project
  6 */
  7
  8#include <linux/delay.h>
  9#include <linux/i2c.h>
 10#include <linux/mfd/core.h>
 11#include <linux/module.h>
 12#include <linux/of.h>
 13#include <linux/reboot.h>
 14#include <linux/regmap.h>
 15
 16#define A500_EC_I2C_ERR_TIMEOUT		500
 17#define A500_EC_POWER_CMD_TIMEOUT	1000
 18
 19/*
 20 * Controller's firmware expects specific command opcodes to be used for the
 21 * corresponding registers. Unsupported commands are skipped by the firmware.
 22 */
 23#define CMD_SHUTDOWN			0x0
 24#define CMD_WARM_REBOOT			0x0
 25#define CMD_COLD_REBOOT			0x1
 26
 27enum {
 28	REG_CURRENT_NOW = 0x03,
 29	REG_SHUTDOWN = 0x52,
 30	REG_WARM_REBOOT = 0x54,
 31	REG_COLD_REBOOT = 0x55,
 32};
 33
 34static struct i2c_client *a500_ec_client_pm_off;
 35
 36static int a500_ec_read(void *context, const void *reg_buf, size_t reg_size,
 37			void *val_buf, size_t val_sizel)
 38{
 39	struct i2c_client *client = context;
 40	unsigned int reg, retries = 5;
 41	u16 *ret_val = val_buf;
 42	s32 ret = 0;
 43
 44	reg = *(u8 *)reg_buf;
 45
 46	while (retries-- > 0) {
 47		ret = i2c_smbus_read_word_data(client, reg);
 48		if (ret >= 0)
 49			break;
 50
 51		msleep(A500_EC_I2C_ERR_TIMEOUT);
 52	}
 53
 54	if (ret < 0) {
 55		dev_err(&client->dev, "read 0x%x failed: %d\n", reg, ret);
 56		return ret;
 57	}
 58
 59	*ret_val = ret;
 60
 61	if (reg == REG_CURRENT_NOW)
 62		fsleep(10000);
 63
 64	return 0;
 65}
 66
 67static int a500_ec_write(void *context, const void *data, size_t count)
 68{
 69	struct i2c_client *client = context;
 70	unsigned int reg, val, retries = 5;
 71	s32 ret = 0;
 72
 73	reg = *(u8  *)(data + 0);
 74	val = *(u16 *)(data + 1);
 75
 76	while (retries-- > 0) {
 77		ret = i2c_smbus_write_word_data(client, reg, val);
 78		if (ret >= 0)
 79			break;
 80
 81		msleep(A500_EC_I2C_ERR_TIMEOUT);
 82	}
 83
 84	if (ret < 0) {
 85		dev_err(&client->dev, "write 0x%x failed: %d\n", reg, ret);
 86		return ret;
 87	}
 88
 89	return 0;
 90}
 91
 92static const struct regmap_config a500_ec_regmap_config = {
 93	.name = "KB930",
 94	.reg_bits = 8,
 95	.val_bits = 16,
 96	.max_register = 0xff,
 97};
 98
 99static const struct regmap_bus a500_ec_regmap_bus = {
100	.reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
101	.val_format_endian_default = REGMAP_ENDIAN_LITTLE,
102	.write = a500_ec_write,
103	.read = a500_ec_read,
104	.max_raw_read = 2,
105};
106
107static void a500_ec_poweroff(void)
108{
109	i2c_smbus_write_word_data(a500_ec_client_pm_off,
110				  REG_SHUTDOWN, CMD_SHUTDOWN);
111
112	mdelay(A500_EC_POWER_CMD_TIMEOUT);
113}
114
115static int a500_ec_restart_notify(struct notifier_block *this,
116				  unsigned long reboot_mode, void *data)
117{
118	if (reboot_mode == REBOOT_WARM)
119		i2c_smbus_write_word_data(a500_ec_client_pm_off,
120					  REG_WARM_REBOOT, CMD_WARM_REBOOT);
121	else
122		i2c_smbus_write_word_data(a500_ec_client_pm_off,
123					  REG_COLD_REBOOT, CMD_COLD_REBOOT);
124
125	mdelay(A500_EC_POWER_CMD_TIMEOUT);
126
127	return NOTIFY_DONE;
128}
129
130static struct notifier_block a500_ec_restart_handler = {
131	.notifier_call = a500_ec_restart_notify,
132	.priority = 200,
133};
134
135static const struct mfd_cell a500_ec_cells[] = {
136	{ .name = "acer-a500-iconia-battery", },
137	{ .name = "acer-a500-iconia-leds", },
138};
139
140static int a500_ec_probe(struct i2c_client *client)
141{
142	struct regmap *regmap;
143	int err;
144
145	regmap = devm_regmap_init(&client->dev, &a500_ec_regmap_bus,
146				  client, &a500_ec_regmap_config);
147	if (IS_ERR(regmap))
148		return PTR_ERR(regmap);
149
150	err = devm_mfd_add_devices(&client->dev, PLATFORM_DEVID_AUTO,
151				   a500_ec_cells, ARRAY_SIZE(a500_ec_cells),
152				   NULL, 0, NULL);
153	if (err) {
154		dev_err(&client->dev, "failed to add sub-devices: %d\n", err);
155		return err;
156	}
157
158	if (of_device_is_system_power_controller(client->dev.of_node)) {
159		a500_ec_client_pm_off = client;
160
161		err = register_restart_handler(&a500_ec_restart_handler);
162		if (err)
163			return err;
164
165		if (!pm_power_off)
166			pm_power_off = a500_ec_poweroff;
167	}
168
169	return 0;
170}
171
172static void a500_ec_remove(struct i2c_client *client)
173{
174	if (of_device_is_system_power_controller(client->dev.of_node)) {
175		if (pm_power_off == a500_ec_poweroff)
176			pm_power_off = NULL;
177
178		unregister_restart_handler(&a500_ec_restart_handler);
179	}
180}
181
182static const struct of_device_id a500_ec_match[] = {
183	{ .compatible = "acer,a500-iconia-ec" },
184	{ }
185};
186MODULE_DEVICE_TABLE(of, a500_ec_match);
187
188static struct i2c_driver a500_ec_driver = {
189	.driver = {
190		.name = "acer-a500-embedded-controller",
191		.of_match_table = a500_ec_match,
192	},
193	.probe = a500_ec_probe,
194	.remove = a500_ec_remove,
195};
196module_i2c_driver(a500_ec_driver);
197
198MODULE_DESCRIPTION("Acer Iconia Tab A500 Embedded Controller driver");
199MODULE_AUTHOR("Dmitry Osipenko <digetx@gmail.com>");
200MODULE_LICENSE("GPL");