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/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>
 21
 22/* Prefix all names to avoid collisions with EC <-> AP nets */
 23static const char cros_ec_gpio_prefix[] = "EC:";
 24
 25/* Setting gpios is only supported when the system is unlocked */
 26static void cros_ec_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
 27{
 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 = {
 31		.val = val,
 32	};
 33	int ret;
 34	ssize_t copied;
 35
 36	copied = strscpy(params.name, name, sizeof(params.name));
 37	if (copied < 0)
 38		return;
 39
 40	ret = cros_ec_cmd(cros_ec, 0, EC_CMD_GPIO_SET, &params,
 41			  sizeof(params), NULL, 0);
 42	if (ret < 0)
 43		dev_err(gc->parent, "error setting gpio%d (%s) on EC: %d\n", gpio, name, ret);
 44}
 45
 46static int cros_ec_gpio_get(struct gpio_chip *gc, unsigned int gpio)
 47{
 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;
 52	int ret;
 53	ssize_t copied;
 54
 55	copied = strscpy(params.name, name, sizeof(params.name));
 56	if (copied < 0)
 57		return -EINVAL;
 58
 59	ret = cros_ec_cmd(cros_ec, 0, EC_CMD_GPIO_GET, &params,
 60			  sizeof(params), &response, sizeof(response));
 61	if (ret < 0) {
 62		dev_err(gc->parent, "error getting gpio%d (%s) on EC: %d\n", gpio, name, ret);
 63		return ret;
 64	}
 65
 66	return response.val;
 67}
 68
 69#define CROS_EC_GPIO_INPUT         BIT(8)
 70#define CROS_EC_GPIO_OUTPUT        BIT(9)
 71
 72static int cros_ec_gpio_get_direction(struct gpio_chip *gc, unsigned int gpio)
 73{
 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,
 79	};
 80	struct ec_response_gpio_get_v1 response;
 81	int ret;
 82
 83	ret = cros_ec_cmd(cros_ec, 1, EC_CMD_GPIO_GET, &params,
 84			  sizeof(params), &response, sizeof(response));
 85	if (ret < 0) {
 86		dev_err(gc->parent, "error getting direction of gpio%d (%s) on EC: %d\n", gpio, name, ret);
 87		return ret;
 88	}
 89
 90	if (response.get_info.flags & CROS_EC_GPIO_INPUT)
 91		return GPIO_LINE_DIRECTION_IN;
 92
 93	if (response.get_info.flags & CROS_EC_GPIO_OUTPUT)
 94		return GPIO_LINE_DIRECTION_OUT;
 95
 96	return -EINVAL;
 97}
 98
 99/* Query EC for all gpio line names */
100static int cros_ec_gpio_init_names(struct cros_ec_device *cros_ec, struct gpio_chip *gc)
101{
102	struct ec_params_gpio_get_v1 params = {
103		.subcmd = EC_GPIO_GET_INFO,
104	};
105	struct ec_response_gpio_get_v1 response;
106	int ret, i;
107	/* EC may not NUL terminate */
108	size_t name_len = strlen(cros_ec_gpio_prefix) + sizeof(response.get_info.name) + 1;
109	ssize_t copied;
110	const char **names;
111	char *str;
112
113	names = devm_kcalloc(gc->parent, gc->ngpio, sizeof(*names), GFP_KERNEL);
114	if (!names)
115		return -ENOMEM;
116	gc->names = names;
117
118	str = devm_kcalloc(gc->parent, gc->ngpio, name_len, GFP_KERNEL);
119	if (!str)
120		return -ENOMEM;
121
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, &params,
126				  sizeof(params), &response, sizeof(response));
127		if (ret < 0) {
128			dev_err_probe(gc->parent, ret, "error getting gpio%d info\n", i);
129			return ret;
130		}
131
132		names[i] = str;
133		copied = scnprintf(str, name_len, "%s%s", cros_ec_gpio_prefix,
134				   response.get_info.name);
135		if (copied < 0)
136			return copied;
137
138		str += copied + 1;
139	}
140
141	return 0;
142}
143
144/* Query EC for number of gpios */
145static int cros_ec_gpio_ngpios(struct cros_ec_device *cros_ec)
146{
147	struct ec_params_gpio_get_v1 params = {
148		.subcmd = EC_GPIO_GET_COUNT,
149	};
150	struct ec_response_gpio_get_v1 response;
151	int ret;
152
153	ret = cros_ec_cmd(cros_ec, 1, EC_CMD_GPIO_GET, &params,
154			  sizeof(params), &response, sizeof(response));
155	if (ret < 0)
156		return ret;
157
158	return response.get_count.val;
159}
160
161static int cros_ec_gpio_probe(struct platform_device *pdev)
162{
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;
168	int ngpios;
169	int ret;
170
171	/* Use the fwnode from the protocol device, e.g. cros-ec-spi */
172	device_set_node(dev, dev_fwnode(cros_ec->dev));
173
174	ngpios = cros_ec_gpio_ngpios(cros_ec);
175	if (ngpios < 0) {
176		dev_err_probe(dev, ngpios, "error getting gpio count\n");
177		return ngpios;
178	}
179
180	gc = devm_kzalloc(dev, sizeof(*gc), GFP_KERNEL);
181	if (!gc)
182		return -ENOMEM;
183
184	gc->ngpio = ngpios;
185	gc->parent = dev;
186	ret = cros_ec_gpio_init_names(cros_ec, gc);
187	if (ret)
188		return ret;
189
190	gc->can_sleep = true;
191	gc->label = dev_name(dev);
192	gc->base = -1;
193	gc->set = cros_ec_gpio_set;
194	gc->get = cros_ec_gpio_get;
195	gc->get_direction = cros_ec_gpio_get_direction;
196
197	return devm_gpiochip_add_data(dev, gc, cros_ec);
198}
199
200static struct platform_driver cros_ec_gpio_driver = {
201	.probe = cros_ec_gpio_probe,
202	.driver = {
203		.name = "cros-ec-gpio",
204	},
205};
206module_platform_driver(cros_ec_gpio_driver);
207
208MODULE_DESCRIPTION("ChromeOS EC GPIO Driver");
209MODULE_LICENSE("GPL");