1 // SPDX-License-Identifier: BSD-2-Clause OR GPL-2.0-or-later
2 /*
3 * ENE KB3930 Embedded Controller Driver
4 *
5 * Copyright (C) 2020 Lubomir Rintel
6 */
7
8 #include <linux/delay.h>
9 #include <linux/gpio/consumer.h>
10 #include <linux/i2c.h>
11 #include <linux/mfd/core.h>
12 #include <linux/module.h>
13 #include <linux/reboot.h>
14 #include <linux/regmap.h>
15
16 /* I2C registers that are multiplexing access to the EC RAM. */
17 enum {
18 EC_DATA_IN = 0x00,
19 EC_RAM_OUT = 0x80,
20 EC_RAM_IN = 0x81,
21 };
22
23 /* EC RAM registers. */
24 enum {
25 EC_MODEL = 0x30,
26 EC_VERSION_MAJ = 0x31,
27 EC_VERSION_MIN = 0x32,
28 };
29
30 struct kb3930 {
31 struct i2c_client *client;
32 struct regmap *ram_regmap;
33 struct gpio_descs *off_gpios;
34 };
35
36 static struct kb3930 *kb3930_power_off;
37
38 #define EC_GPIO_WAVE 0
39 #define EC_GPIO_OFF_MODE 1
40
41 #define EC_OFF_MODE_REBOOT 0
42 #define EC_OFF_MODE_POWER 1
43
kb3930_off(struct kb3930 * ddata,int off_mode)44 static void kb3930_off(struct kb3930 *ddata, int off_mode)
45 {
46 gpiod_direction_output(ddata->off_gpios->desc[EC_GPIO_OFF_MODE],
47 off_mode);
48
49 /*
50 * This creates a 10 Hz wave on EC_GPIO_WAVE that signals a
51 * shutdown request to the EC. Once the EC detects it, it will
52 * proceed to turn the power off or reset the board depending on
53 * the value of EC_GPIO_OFF_MODE.
54 */
55 while (1) {
56 mdelay(50);
57 gpiod_direction_output(ddata->off_gpios->desc[EC_GPIO_WAVE], 0);
58 mdelay(50);
59 gpiod_direction_output(ddata->off_gpios->desc[EC_GPIO_WAVE], 1);
60 }
61 }
62
kb3930_restart(struct notifier_block * this,unsigned long mode,void * cmd)63 static int kb3930_restart(struct notifier_block *this,
64 unsigned long mode, void *cmd)
65 {
66 kb3930_off(kb3930_power_off, EC_OFF_MODE_REBOOT);
67 return NOTIFY_DONE;
68 }
69
kb3930_pm_power_off(void)70 static void kb3930_pm_power_off(void)
71 {
72 kb3930_off(kb3930_power_off, EC_OFF_MODE_POWER);
73 }
74
75 static struct notifier_block kb3930_restart_nb = {
76 .notifier_call = kb3930_restart,
77 };
78
79 static const struct mfd_cell ariel_ec_cells[] = {
80 { .name = "dell-wyse-ariel-led", },
81 { .name = "dell-wyse-ariel-power", },
82 };
83
kb3930_ec_ram_reg_write(void * context,unsigned int reg,unsigned int val)84 static int kb3930_ec_ram_reg_write(void *context, unsigned int reg,
85 unsigned int val)
86 {
87 struct kb3930 *ddata = context;
88
89 return i2c_smbus_write_word_data(ddata->client, EC_RAM_OUT,
90 (val << 8) | reg);
91 }
92
kb3930_ec_ram_reg_read(void * context,unsigned int reg,unsigned int * val)93 static int kb3930_ec_ram_reg_read(void *context, unsigned int reg,
94 unsigned int *val)
95 {
96 struct kb3930 *ddata = context;
97 int ret;
98
99 ret = i2c_smbus_write_word_data(ddata->client, EC_RAM_IN, reg);
100 if (ret < 0)
101 return ret;
102
103 ret = i2c_smbus_read_word_data(ddata->client, EC_DATA_IN);
104 if (ret < 0)
105 return ret;
106
107 *val = ret >> 8;
108 return 0;
109 }
110
111 static const struct regmap_config kb3930_ram_regmap_config = {
112 .name = "ec_ram",
113 .reg_bits = 8,
114 .val_bits = 8,
115 .reg_stride = 1,
116 .max_register = 0xff,
117 .reg_write = kb3930_ec_ram_reg_write,
118 .reg_read = kb3930_ec_ram_reg_read,
119 .fast_io = false,
120 };
121
kb3930_probe(struct i2c_client * client)122 static int kb3930_probe(struct i2c_client *client)
123 {
124 struct device *dev = &client->dev;
125 struct device_node *np = dev->of_node;
126 struct kb3930 *ddata;
127 unsigned int model;
128 int ret;
129
130 ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
131 if (!ddata)
132 return -ENOMEM;
133
134 kb3930_power_off = ddata;
135 ddata->client = client;
136 i2c_set_clientdata(client, ddata);
137
138 ddata->ram_regmap = devm_regmap_init(dev, NULL, ddata,
139 &kb3930_ram_regmap_config);
140 if (IS_ERR(ddata->ram_regmap))
141 return PTR_ERR(ddata->ram_regmap);
142
143 ret = regmap_read(ddata->ram_regmap, EC_MODEL, &model);
144 if (ret < 0)
145 return ret;
146
147 /* Currently we only support the cells present on Dell Ariel model. */
148 if (model != 'J') {
149 dev_err(dev, "unknown board model: %02x\n", model);
150 return -ENODEV;
151 }
152
153 ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_AUTO,
154 ariel_ec_cells,
155 ARRAY_SIZE(ariel_ec_cells),
156 NULL, 0, NULL);
157 if (ret)
158 return ret;
159
160 if (of_property_read_bool(np, "system-power-controller")) {
161 ddata->off_gpios =
162 devm_gpiod_get_array_optional(dev, "off", GPIOD_IN);
163 if (IS_ERR(ddata->off_gpios))
164 return PTR_ERR(ddata->off_gpios);
165 if (ddata->off_gpios->ndescs < 2) {
166 dev_err(dev, "invalid off-gpios property\n");
167 return -EINVAL;
168 }
169 }
170
171 if (ddata->off_gpios) {
172 register_restart_handler(&kb3930_restart_nb);
173 if (!pm_power_off)
174 pm_power_off = kb3930_pm_power_off;
175 }
176
177 return 0;
178 }
179
kb3930_remove(struct i2c_client * client)180 static void kb3930_remove(struct i2c_client *client)
181 {
182 struct kb3930 *ddata = i2c_get_clientdata(client);
183
184 if (ddata->off_gpios) {
185 if (pm_power_off == kb3930_pm_power_off)
186 pm_power_off = NULL;
187 unregister_restart_handler(&kb3930_restart_nb);
188 }
189 kb3930_power_off = NULL;
190 }
191
192 static const struct of_device_id kb3930_dt_ids[] = {
193 { .compatible = "ene,kb3930" },
194 { }
195 };
196 MODULE_DEVICE_TABLE(of, kb3930_dt_ids);
197
198 static struct i2c_driver kb3930_driver = {
199 .probe = kb3930_probe,
200 .remove = kb3930_remove,
201 .driver = {
202 .name = "ene-kb3930",
203 .of_match_table = kb3930_dt_ids,
204 },
205 };
206 module_i2c_driver(kb3930_driver);
207
208 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
209 MODULE_DESCRIPTION("ENE KB3930 Embedded Controller Driver");
210 MODULE_LICENSE("Dual BSD/GPL");
211