1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright 2024 Google LLC
4 *
5 * This driver provides the ability to control GPIOs on the Chrome OS EC.
6 * There isn't any direction control, and setting values on GPIOs is only
7 * possible when the system is unlocked.
8 */
9
10 #include <linux/bitops.h>
11 #include <linux/device.h>
12 #include <linux/errno.h>
13 #include <linux/gpio/driver.h>
14 #include <linux/kernel.h>
15 #include <linux/mod_devicetable.h>
16 #include <linux/module.h>
17 #include <linux/platform_data/cros_ec_commands.h>
18 #include <linux/platform_data/cros_ec_proto.h>
19 #include <linux/platform_device.h>
20 #include <linux/property.h>
21 #include <linux/slab.h>
22
23 /* Prefix all names to avoid collisions with EC <-> AP nets */
24 static const char cros_ec_gpio_prefix[] = "EC:";
25
26 /* Setting gpios is only supported when the system is unlocked */
cros_ec_gpio_set(struct gpio_chip * gc,unsigned int gpio,int val)27 static void cros_ec_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
28 {
29 const char *name = gc->names[gpio] + strlen(cros_ec_gpio_prefix);
30 struct cros_ec_device *cros_ec = gpiochip_get_data(gc);
31 struct ec_params_gpio_set params = {
32 .val = val,
33 };
34 int ret;
35 ssize_t copied;
36
37 copied = strscpy(params.name, name, sizeof(params.name));
38 if (copied < 0)
39 return;
40
41 ret = cros_ec_cmd(cros_ec, 0, EC_CMD_GPIO_SET, ¶ms,
42 sizeof(params), NULL, 0);
43 if (ret < 0)
44 dev_err(gc->parent, "error setting gpio%d (%s) on EC: %d\n", gpio, name, ret);
45 }
46
cros_ec_gpio_get(struct gpio_chip * gc,unsigned int gpio)47 static int cros_ec_gpio_get(struct gpio_chip *gc, unsigned int gpio)
48 {
49 const char *name = gc->names[gpio] + strlen(cros_ec_gpio_prefix);
50 struct cros_ec_device *cros_ec = gpiochip_get_data(gc);
51 struct ec_params_gpio_get params;
52 struct ec_response_gpio_get response;
53 int ret;
54 ssize_t copied;
55
56 copied = strscpy(params.name, name, sizeof(params.name));
57 if (copied < 0)
58 return -EINVAL;
59
60 ret = cros_ec_cmd(cros_ec, 0, EC_CMD_GPIO_GET, ¶ms,
61 sizeof(params), &response, sizeof(response));
62 if (ret < 0) {
63 dev_err(gc->parent, "error getting gpio%d (%s) on EC: %d\n", gpio, name, ret);
64 return ret;
65 }
66
67 return response.val;
68 }
69
70 #define CROS_EC_GPIO_INPUT BIT(8)
71 #define CROS_EC_GPIO_OUTPUT BIT(9)
72
cros_ec_gpio_get_direction(struct gpio_chip * gc,unsigned int gpio)73 static int cros_ec_gpio_get_direction(struct gpio_chip *gc, unsigned int gpio)
74 {
75 const char *name = gc->names[gpio] + strlen(cros_ec_gpio_prefix);
76 struct cros_ec_device *cros_ec = gpiochip_get_data(gc);
77 struct ec_params_gpio_get_v1 params = {
78 .subcmd = EC_GPIO_GET_INFO,
79 .get_info.index = gpio,
80 };
81 struct ec_response_gpio_get_v1 response;
82 int ret;
83
84 ret = cros_ec_cmd(cros_ec, 1, EC_CMD_GPIO_GET, ¶ms,
85 sizeof(params), &response, sizeof(response));
86 if (ret < 0) {
87 dev_err(gc->parent, "error getting direction of gpio%d (%s) on EC: %d\n", gpio, name, ret);
88 return ret;
89 }
90
91 if (response.get_info.flags & CROS_EC_GPIO_INPUT)
92 return GPIO_LINE_DIRECTION_IN;
93
94 if (response.get_info.flags & CROS_EC_GPIO_OUTPUT)
95 return GPIO_LINE_DIRECTION_OUT;
96
97 return -EINVAL;
98 }
99
100 /* Query EC for all gpio line names */
cros_ec_gpio_init_names(struct cros_ec_device * cros_ec,struct gpio_chip * gc)101 static int cros_ec_gpio_init_names(struct cros_ec_device *cros_ec, struct gpio_chip *gc)
102 {
103 struct ec_params_gpio_get_v1 params = {
104 .subcmd = EC_GPIO_GET_INFO,
105 };
106 struct ec_response_gpio_get_v1 response;
107 int ret, i;
108 /* EC may not NUL terminate */
109 size_t name_len = strlen(cros_ec_gpio_prefix) + sizeof(response.get_info.name) + 1;
110 ssize_t copied;
111 const char **names;
112 char *str;
113
114 names = devm_kcalloc(gc->parent, gc->ngpio, sizeof(*names), GFP_KERNEL);
115 if (!names)
116 return -ENOMEM;
117 gc->names = names;
118
119 str = devm_kcalloc(gc->parent, gc->ngpio, name_len, GFP_KERNEL);
120 if (!str)
121 return -ENOMEM;
122
123 /* Get gpio line names one at a time */
124 for (i = 0; i < gc->ngpio; i++) {
125 params.get_info.index = i;
126 ret = cros_ec_cmd(cros_ec, 1, EC_CMD_GPIO_GET, ¶ms,
127 sizeof(params), &response, sizeof(response));
128 if (ret < 0) {
129 dev_err_probe(gc->parent, ret, "error getting gpio%d info\n", i);
130 return ret;
131 }
132
133 names[i] = str;
134 copied = scnprintf(str, name_len, "%s%s", cros_ec_gpio_prefix,
135 response.get_info.name);
136 if (copied < 0)
137 return copied;
138
139 str += copied + 1;
140 }
141
142 return 0;
143 }
144
145 /* Query EC for number of gpios */
cros_ec_gpio_ngpios(struct cros_ec_device * cros_ec)146 static int cros_ec_gpio_ngpios(struct cros_ec_device *cros_ec)
147 {
148 struct ec_params_gpio_get_v1 params = {
149 .subcmd = EC_GPIO_GET_COUNT,
150 };
151 struct ec_response_gpio_get_v1 response;
152 int ret;
153
154 ret = cros_ec_cmd(cros_ec, 1, EC_CMD_GPIO_GET, ¶ms,
155 sizeof(params), &response, sizeof(response));
156 if (ret < 0)
157 return ret;
158
159 return response.get_count.val;
160 }
161
cros_ec_gpio_probe(struct platform_device * pdev)162 static int cros_ec_gpio_probe(struct platform_device *pdev)
163 {
164 struct device *dev = &pdev->dev;
165 struct device *parent = dev->parent;
166 struct cros_ec_dev *ec_dev = dev_get_drvdata(parent);
167 struct cros_ec_device *cros_ec = ec_dev->ec_dev;
168 struct gpio_chip *gc;
169 int ngpios;
170 int ret;
171
172 /* Use the fwnode from the protocol device, e.g. cros-ec-spi */
173 device_set_node(dev, dev_fwnode(cros_ec->dev));
174
175 ngpios = cros_ec_gpio_ngpios(cros_ec);
176 if (ngpios < 0) {
177 dev_err_probe(dev, ngpios, "error getting gpio count\n");
178 return ngpios;
179 }
180
181 gc = devm_kzalloc(dev, sizeof(*gc), GFP_KERNEL);
182 if (!gc)
183 return -ENOMEM;
184
185 gc->ngpio = ngpios;
186 gc->parent = dev;
187 ret = cros_ec_gpio_init_names(cros_ec, gc);
188 if (ret)
189 return ret;
190
191 gc->can_sleep = true;
192 gc->label = dev_name(dev);
193 gc->base = -1;
194 gc->set = cros_ec_gpio_set;
195 gc->get = cros_ec_gpio_get;
196 gc->get_direction = cros_ec_gpio_get_direction;
197
198 return devm_gpiochip_add_data(dev, gc, cros_ec);
199 }
200
201 static const struct platform_device_id cros_ec_gpio_id[] = {
202 { "cros-ec-gpio", 0 },
203 {}
204 };
205 MODULE_DEVICE_TABLE(platform, cros_ec_gpio_id);
206
207 static struct platform_driver cros_ec_gpio_driver = {
208 .probe = cros_ec_gpio_probe,
209 .driver = {
210 .name = "cros-ec-gpio",
211 },
212 .id_table = cros_ec_gpio_id,
213 };
214 module_platform_driver(cros_ec_gpio_driver);
215
216 MODULE_DESCRIPTION("ChromeOS EC GPIO Driver");
217 MODULE_LICENSE("GPL");
218