1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright 2024 Google LLC
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.
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/module.h>
16 #include <linux/platform_data/cros_ec_commands.h>
17 #include <linux/platform_data/cros_ec_proto.h>
18 #include <linux/platform_device.h>
19 #include <linux/property.h>
20 #include <linux/slab.h>
22 /* Prefix all names to avoid collisions with EC <-> AP nets */
23 static const char cros_ec_gpio_prefix[] = "EC:";
25 /* Setting gpios is only supported when the system is unlocked */
26 static void cros_ec_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
28 const char *name = gc->names[gpio] + strlen(cros_ec_gpio_prefix);
29 struct cros_ec_device *cros_ec = gpiochip_get_data(gc);
30 struct ec_params_gpio_set params = {
36 copied = strscpy(params.name, name, sizeof(params.name));
40 ret = cros_ec_cmd(cros_ec, 0, EC_CMD_GPIO_SET, ¶ms,
41 sizeof(params), NULL, 0);
43 dev_err(gc->parent, "error setting gpio%d (%s) on EC: %d\n", gpio, name, ret);
46 static int cros_ec_gpio_get(struct gpio_chip *gc, unsigned int gpio)
48 const char *name = gc->names[gpio] + strlen(cros_ec_gpio_prefix);
49 struct cros_ec_device *cros_ec = gpiochip_get_data(gc);
50 struct ec_params_gpio_get params;
51 struct ec_response_gpio_get response;
55 copied = strscpy(params.name, name, sizeof(params.name));
59 ret = cros_ec_cmd(cros_ec, 0, EC_CMD_GPIO_GET, ¶ms,
60 sizeof(params), &response, sizeof(response));
62 dev_err(gc->parent, "error getting gpio%d (%s) on EC: %d\n", gpio, name, ret);
69 #define CROS_EC_GPIO_INPUT BIT(8)
70 #define CROS_EC_GPIO_OUTPUT BIT(9)
72 static int cros_ec_gpio_get_direction(struct gpio_chip *gc, unsigned int gpio)
74 const char *name = gc->names[gpio] + strlen(cros_ec_gpio_prefix);
75 struct cros_ec_device *cros_ec = gpiochip_get_data(gc);
76 struct ec_params_gpio_get_v1 params = {
77 .subcmd = EC_GPIO_GET_INFO,
78 .get_info.index = gpio,
80 struct ec_response_gpio_get_v1 response;
83 ret = cros_ec_cmd(cros_ec, 1, EC_CMD_GPIO_GET, ¶ms,
84 sizeof(params), &response, sizeof(response));
86 dev_err(gc->parent, "error getting direction of gpio%d (%s) on EC: %d\n", gpio, name, ret);
90 if (response.get_info.flags & CROS_EC_GPIO_INPUT)
91 return GPIO_LINE_DIRECTION_IN;
93 if (response.get_info.flags & CROS_EC_GPIO_OUTPUT)
94 return GPIO_LINE_DIRECTION_OUT;
99 /* Query EC for all gpio line names */
100 static int cros_ec_gpio_init_names(struct cros_ec_device *cros_ec, struct gpio_chip *gc)
102 struct ec_params_gpio_get_v1 params = {
103 .subcmd = EC_GPIO_GET_INFO,
105 struct ec_response_gpio_get_v1 response;
107 /* EC may not NUL terminate */
108 size_t name_len = strlen(cros_ec_gpio_prefix) + sizeof(response.get_info.name) + 1;
113 names = devm_kcalloc(gc->parent, gc->ngpio, sizeof(*names), GFP_KERNEL);
118 str = devm_kcalloc(gc->parent, gc->ngpio, name_len, GFP_KERNEL);
122 /* Get gpio line names one at a time */
123 for (i = 0; i < gc->ngpio; i++) {
124 params.get_info.index = i;
125 ret = cros_ec_cmd(cros_ec, 1, EC_CMD_GPIO_GET, ¶ms,
126 sizeof(params), &response, sizeof(response));
128 dev_err_probe(gc->parent, ret, "error getting gpio%d info\n", i);
133 copied = scnprintf(str, name_len, "%s%s", cros_ec_gpio_prefix,
134 response.get_info.name);
144 /* Query EC for number of gpios */
145 static int cros_ec_gpio_ngpios(struct cros_ec_device *cros_ec)
147 struct ec_params_gpio_get_v1 params = {
148 .subcmd = EC_GPIO_GET_COUNT,
150 struct ec_response_gpio_get_v1 response;
153 ret = cros_ec_cmd(cros_ec, 1, EC_CMD_GPIO_GET, ¶ms,
154 sizeof(params), &response, sizeof(response));
158 return response.get_count.val;
161 static int cros_ec_gpio_probe(struct platform_device *pdev)
163 struct device *dev = &pdev->dev;
164 struct device *parent = dev->parent;
165 struct cros_ec_dev *ec_dev = dev_get_drvdata(parent);
166 struct cros_ec_device *cros_ec = ec_dev->ec_dev;
167 struct gpio_chip *gc;
171 /* Use the fwnode from the protocol device, e.g. cros-ec-spi */
172 device_set_node(dev, dev_fwnode(cros_ec->dev));
174 ngpios = cros_ec_gpio_ngpios(cros_ec);
176 dev_err_probe(dev, ngpios, "error getting gpio count\n");
180 gc = devm_kzalloc(dev, sizeof(*gc), GFP_KERNEL);
186 ret = cros_ec_gpio_init_names(cros_ec, gc);
190 gc->can_sleep = true;
191 gc->label = dev_name(dev);
193 gc->set = cros_ec_gpio_set;
194 gc->get = cros_ec_gpio_get;
195 gc->get_direction = cros_ec_gpio_get_direction;
197 return devm_gpiochip_add_data(dev, gc, cros_ec);
200 static struct platform_driver cros_ec_gpio_driver = {
201 .probe = cros_ec_gpio_probe,
203 .name = "cros-ec-gpio",
206 module_platform_driver(cros_ec_gpio_driver);
208 MODULE_DESCRIPTION("ChromeOS EC GPIO Driver");
209 MODULE_LICENSE("GPL");