xref: /openbmc/linux/drivers/mfd/ene-kb3930.c (revision 9816d859)
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