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(ec_dev: cros_ec, version: 0, EC_CMD_GPIO_SET, outdata: &params,
41 outsize: sizeof(params), NULL, insize: 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(ec_dev: cros_ec, version: 0, EC_CMD_GPIO_GET, outdata: &params,
60 outsize: sizeof(params), indata: &response, insize: 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(ec_dev: cros_ec, version: 1, EC_CMD_GPIO_GET, outdata: &params,
84 outsize: sizeof(params), indata: &response, insize: 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(dev: gc->parent, n: gc->ngpio, size: sizeof(*names), GFP_KERNEL);
114 if (!names)
115 return -ENOMEM;
116 gc->names = names;
117
118 str = devm_kcalloc(dev: gc->parent, n: gc->ngpio, size: 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(ec_dev: cros_ec, version: 1, EC_CMD_GPIO_GET, outdata: &params,
126 outsize: sizeof(params), indata: &response, insize: sizeof(response));
127 if (ret < 0) {
128 dev_err_probe(dev: gc->parent, err: ret, fmt: "error getting gpio%d info\n", i);
129 return ret;
130 }
131
132 names[i] = str;
133 copied = scnprintf(buf: str, size: name_len, fmt: "%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(ec_dev: cros_ec, version: 1, EC_CMD_GPIO_GET, outdata: &params,
154 outsize: sizeof(params), indata: &response, insize: 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(dev: 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, err: ngpios, fmt: "error getting gpio count\n");
177 return ngpios;
178 }
179
180 gc = devm_kzalloc(dev, size: 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");
210

source code of linux/drivers/gpio/gpio-cros-ec.c