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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright 2024 Google LLC4 *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 only7 * 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, ¶ms,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, ¶ms,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, ¶ms,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, ¶ms,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, ¶ms,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");218