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 */ 24 static const char cros_ec_gpio_prefix[] = "EC:"; 25 26 /* Setting gpios is only supported when the system is unlocked */ 27 static int 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 ssize_t copied; 35 36 copied = strscpy(params.name, name, sizeof(params.name)); 37 if (copied < 0) 38 return copied; 39 40 return cros_ec_cmd(cros_ec, 0, EC_CMD_GPIO_SET, ¶ms, 41 sizeof(params), NULL, 0); 42 } 43 44 static int cros_ec_gpio_get(struct gpio_chip *gc, unsigned int gpio) 45 { 46 const char *name = gc->names[gpio] + strlen(cros_ec_gpio_prefix); 47 struct cros_ec_device *cros_ec = gpiochip_get_data(gc); 48 struct ec_params_gpio_get params; 49 struct ec_response_gpio_get response; 50 int ret; 51 ssize_t copied; 52 53 copied = strscpy(params.name, name, sizeof(params.name)); 54 if (copied < 0) 55 return -EINVAL; 56 57 ret = cros_ec_cmd(cros_ec, 0, EC_CMD_GPIO_GET, ¶ms, 58 sizeof(params), &response, sizeof(response)); 59 if (ret < 0) { 60 dev_err(gc->parent, "error getting gpio%d (%s) on EC: %d\n", gpio, name, ret); 61 return ret; 62 } 63 64 return response.val; 65 } 66 67 #define CROS_EC_GPIO_INPUT BIT(8) 68 #define CROS_EC_GPIO_OUTPUT BIT(9) 69 70 static int cros_ec_gpio_get_direction(struct gpio_chip *gc, unsigned int gpio) 71 { 72 const char *name = gc->names[gpio] + strlen(cros_ec_gpio_prefix); 73 struct cros_ec_device *cros_ec = gpiochip_get_data(gc); 74 struct ec_params_gpio_get_v1 params = { 75 .subcmd = EC_GPIO_GET_INFO, 76 .get_info.index = gpio, 77 }; 78 struct ec_response_gpio_get_v1 response; 79 int ret; 80 81 ret = cros_ec_cmd(cros_ec, 1, EC_CMD_GPIO_GET, ¶ms, 82 sizeof(params), &response, sizeof(response)); 83 if (ret < 0) { 84 dev_err(gc->parent, "error getting direction of gpio%d (%s) on EC: %d\n", gpio, name, ret); 85 return ret; 86 } 87 88 if (response.get_info.flags & CROS_EC_GPIO_INPUT) 89 return GPIO_LINE_DIRECTION_IN; 90 91 if (response.get_info.flags & CROS_EC_GPIO_OUTPUT) 92 return GPIO_LINE_DIRECTION_OUT; 93 94 return -EINVAL; 95 } 96 97 /* Query EC for all gpio line names */ 98 static int cros_ec_gpio_init_names(struct cros_ec_device *cros_ec, struct gpio_chip *gc) 99 { 100 struct ec_params_gpio_get_v1 params = { 101 .subcmd = EC_GPIO_GET_INFO, 102 }; 103 struct ec_response_gpio_get_v1 response; 104 int ret, i; 105 /* EC may not NUL terminate */ 106 size_t name_len = strlen(cros_ec_gpio_prefix) + sizeof(response.get_info.name) + 1; 107 ssize_t copied; 108 const char **names; 109 char *str; 110 111 names = devm_kcalloc(gc->parent, gc->ngpio, sizeof(*names), GFP_KERNEL); 112 if (!names) 113 return -ENOMEM; 114 gc->names = names; 115 116 str = devm_kcalloc(gc->parent, gc->ngpio, name_len, GFP_KERNEL); 117 if (!str) 118 return -ENOMEM; 119 120 /* Get gpio line names one at a time */ 121 for (i = 0; i < gc->ngpio; i++) { 122 params.get_info.index = i; 123 ret = cros_ec_cmd(cros_ec, 1, EC_CMD_GPIO_GET, ¶ms, 124 sizeof(params), &response, sizeof(response)); 125 if (ret < 0) { 126 dev_err_probe(gc->parent, ret, "error getting gpio%d info\n", i); 127 return ret; 128 } 129 130 names[i] = str; 131 copied = scnprintf(str, name_len, "%s%s", cros_ec_gpio_prefix, 132 response.get_info.name); 133 if (copied < 0) 134 return copied; 135 136 str += copied + 1; 137 } 138 139 return 0; 140 } 141 142 /* Query EC for number of gpios */ 143 static int cros_ec_gpio_ngpios(struct cros_ec_device *cros_ec) 144 { 145 struct ec_params_gpio_get_v1 params = { 146 .subcmd = EC_GPIO_GET_COUNT, 147 }; 148 struct ec_response_gpio_get_v1 response; 149 int ret; 150 151 ret = cros_ec_cmd(cros_ec, 1, EC_CMD_GPIO_GET, ¶ms, 152 sizeof(params), &response, sizeof(response)); 153 if (ret < 0) 154 return ret; 155 156 return response.get_count.val; 157 } 158 159 static int cros_ec_gpio_probe(struct platform_device *pdev) 160 { 161 struct device *dev = &pdev->dev; 162 struct device *parent = dev->parent; 163 struct cros_ec_dev *ec_dev = dev_get_drvdata(parent); 164 struct cros_ec_device *cros_ec = ec_dev->ec_dev; 165 struct gpio_chip *gc; 166 int ngpios; 167 int ret; 168 169 /* Use the fwnode from the protocol device, e.g. cros-ec-spi */ 170 device_set_node(dev, dev_fwnode(cros_ec->dev)); 171 172 ngpios = cros_ec_gpio_ngpios(cros_ec); 173 if (ngpios < 0) { 174 dev_err_probe(dev, ngpios, "error getting gpio count\n"); 175 return ngpios; 176 } 177 178 gc = devm_kzalloc(dev, sizeof(*gc), GFP_KERNEL); 179 if (!gc) 180 return -ENOMEM; 181 182 gc->ngpio = ngpios; 183 gc->parent = dev; 184 ret = cros_ec_gpio_init_names(cros_ec, gc); 185 if (ret) 186 return ret; 187 188 gc->can_sleep = true; 189 gc->label = dev_name(dev); 190 gc->base = -1; 191 gc->set_rv = cros_ec_gpio_set; 192 gc->get = cros_ec_gpio_get; 193 gc->get_direction = cros_ec_gpio_get_direction; 194 195 return devm_gpiochip_add_data(dev, gc, cros_ec); 196 } 197 198 static const struct platform_device_id cros_ec_gpio_id[] = { 199 { "cros-ec-gpio", 0 }, 200 {} 201 }; 202 MODULE_DEVICE_TABLE(platform, cros_ec_gpio_id); 203 204 static struct platform_driver cros_ec_gpio_driver = { 205 .probe = cros_ec_gpio_probe, 206 .driver = { 207 .name = "cros-ec-gpio", 208 }, 209 .id_table = cros_ec_gpio_id, 210 }; 211 module_platform_driver(cros_ec_gpio_driver); 212 213 MODULE_DESCRIPTION("ChromeOS EC GPIO Driver"); 214 MODULE_LICENSE("GPL"); 215