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 */
 24static const char cros_ec_gpio_prefix[] = "EC:";
 25
 26/* Setting gpios is only supported when the system is unlocked */
 27static 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, &params,
 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
 47static 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, &params,
 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
 73static 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, &params,
 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 */
101static 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, &params,
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 */
146static 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, &params,
155			  sizeof(params), &response, sizeof(response));
156	if (ret < 0)
157		return ret;
158
159	return response.get_count.val;
160}
161
162static 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
201static const struct platform_device_id cros_ec_gpio_id[] = {
202	{ "cros-ec-gpio", 0 },
203	{}
204};
205MODULE_DEVICE_TABLE(platform, cros_ec_gpio_id);
206
207static 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};
214module_platform_driver(cros_ec_gpio_driver);
215
216MODULE_DESCRIPTION("ChromeOS EC GPIO Driver");
217MODULE_LICENSE("GPL");