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 */ 23 static const char cros_ec_gpio_prefix[] = "EC:"; 24 25 /* Setting gpios is only supported when the system is unlocked */ 26 static 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, ¶ms, 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 46 static 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, ¶ms, 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 72 static 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, ¶ms, 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 */ 100 static 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, ¶ms, 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 */ 145 static 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, ¶ms, 154 sizeof(params), &response, sizeof(response)); 155 if (ret < 0) 156 return ret; 157 158 return response.get_count.val; 159 } 160 161 static 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 } 199 200 static struct platform_driver cros_ec_gpio_driver = { 201 .probe = cros_ec_gpio_probe, 202 .driver = { 203 .name = "cros-ec-gpio", 204 }, 205 }; 206 module_platform_driver(cros_ec_gpio_driver); 207 208 MODULE_DESCRIPTION("ChromeOS EC GPIO Driver"); 209 MODULE_LICENSE("GPL"); 210