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");
201