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 */ cros_ec_gpio_set(struct gpio_chip * gc,unsigned int gpio,int val)27 static 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 cros_ec_gpio_get(struct gpio_chip * gc,unsigned int gpio)47 static 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 cros_ec_gpio_get_direction(struct gpio_chip * gc,unsigned int gpio)73 static 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 */ cros_ec_gpio_init_names(struct cros_ec_device * cros_ec,struct gpio_chip * gc)101 static 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 */ cros_ec_gpio_ngpios(struct cros_ec_device * cros_ec)146 static 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 cros_ec_gpio_probe(struct platform_device * pdev)162 static 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 } 200 201 static const struct platform_device_id cros_ec_gpio_id[] = { 202 { "cros-ec-gpio", 0 }, 203 {} 204 }; 205 MODULE_DEVICE_TABLE(platform, cros_ec_gpio_id); 206 207 static 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 }; 214 module_platform_driver(cros_ec_gpio_driver); 215 216 MODULE_DESCRIPTION("ChromeOS EC GPIO Driver"); 217 MODULE_LICENSE("GPL"); 218