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/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>
23 /* Prefix all names to avoid collisions with EC <-> AP nets */
24 static const char cros_ec_gpio_prefix[] = "EC:";
26 /* Setting gpios is only supported when the system is unlocked */
27 static void cros_ec_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
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 = {
37 copied = strscpy(params.name, name, sizeof(params.name));
41 ret = cros_ec_cmd(cros_ec, 0, EC_CMD_GPIO_SET, ¶ms,
42 sizeof(params), NULL, 0);
44 dev_err(gc->parent, "error setting gpio%d (%s) on EC: %d\n", gpio, name, ret);
47 static int cros_ec_gpio_get(struct gpio_chip *gc, unsigned int gpio)
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;
56 copied = strscpy(params.name, name, sizeof(params.name));
60 ret = cros_ec_cmd(cros_ec, 0, EC_CMD_GPIO_GET, ¶ms,
61 sizeof(params), &response, sizeof(response));
63 dev_err(gc->parent, "error getting gpio%d (%s) on EC: %d\n", gpio, name, ret);
70 #define CROS_EC_GPIO_INPUT BIT(8)
71 #define CROS_EC_GPIO_OUTPUT BIT(9)
73 static int cros_ec_gpio_get_direction(struct gpio_chip *gc, unsigned int gpio)
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,
81 struct ec_response_gpio_get_v1 response;
84 ret = cros_ec_cmd(cros_ec, 1, EC_CMD_GPIO_GET, ¶ms,
85 sizeof(params), &response, sizeof(response));
87 dev_err(gc->parent, "error getting direction of gpio%d (%s) on EC: %d\n", gpio, name, ret);
91 if (response.get_info.flags & CROS_EC_GPIO_INPUT)
92 return GPIO_LINE_DIRECTION_IN;
94 if (response.get_info.flags & CROS_EC_GPIO_OUTPUT)
95 return GPIO_LINE_DIRECTION_OUT;
100 /* Query EC for all gpio line names */
101 static int cros_ec_gpio_init_names(struct cros_ec_device *cros_ec, struct gpio_chip *gc)
103 struct ec_params_gpio_get_v1 params = {
104 .subcmd = EC_GPIO_GET_INFO,
106 struct ec_response_gpio_get_v1 response;
108 /* EC may not NUL terminate */
109 size_t name_len = strlen(cros_ec_gpio_prefix) + sizeof(response.get_info.name) + 1;
114 names = devm_kcalloc(gc->parent, gc->ngpio, sizeof(*names), GFP_KERNEL);
119 str = devm_kcalloc(gc->parent, gc->ngpio, name_len, GFP_KERNEL);
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));
129 dev_err_probe(gc->parent, ret, "error getting gpio%d info\n", i);
134 copied = scnprintf(str, name_len, "%s%s", cros_ec_gpio_prefix,
135 response.get_info.name);
145 /* Query EC for number of gpios */
146 static int cros_ec_gpio_ngpios(struct cros_ec_device *cros_ec)
148 struct ec_params_gpio_get_v1 params = {
149 .subcmd = EC_GPIO_GET_COUNT,
151 struct ec_response_gpio_get_v1 response;
154 ret = cros_ec_cmd(cros_ec, 1, EC_CMD_GPIO_GET, ¶ms,
155 sizeof(params), &response, sizeof(response));
159 return response.get_count.val;
162 static int cros_ec_gpio_probe(struct platform_device *pdev)
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;
172 /* Use the fwnode from the protocol device, e.g. cros-ec-spi */
173 device_set_node(dev, dev_fwnode(cros_ec->dev));
175 ngpios = cros_ec_gpio_ngpios(cros_ec);
177 dev_err_probe(dev, ngpios, "error getting gpio count\n");
181 gc = devm_kzalloc(dev, sizeof(*gc), GFP_KERNEL);
187 ret = cros_ec_gpio_init_names(cros_ec, gc);
191 gc->can_sleep = true;
192 gc->label = dev_name(dev);
194 gc->set = cros_ec_gpio_set;
195 gc->get = cros_ec_gpio_get;
196 gc->get_direction = cros_ec_gpio_get_direction;
198 return devm_gpiochip_add_data(dev, gc, cros_ec);
201 static const struct platform_device_id cros_ec_gpio_id[] = {
202 { "cros-ec-gpio", 0 },
205 MODULE_DEVICE_TABLE(platform, cros_ec_gpio_id);
207 static struct platform_driver cros_ec_gpio_driver = {
208 .probe = cros_ec_gpio_probe,
210 .name = "cros-ec-gpio",
212 .id_table = cros_ec_gpio_id,
214 module_platform_driver(cros_ec_gpio_driver);
216 MODULE_DESCRIPTION("ChromeOS EC GPIO Driver");
217 MODULE_LICENSE("GPL");