diff options
Diffstat (limited to 'drivers/gpio/gpio-cros-ec.c')
| -rw-r--r-- | drivers/gpio/gpio-cros-ec.c | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-cros-ec.c b/drivers/gpio/gpio-cros-ec.c new file mode 100644 index 000000000..842e1c060 --- /dev/null +++ b/drivers/gpio/gpio-cros-ec.c @@ -0,0 +1,209 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright 2024 Google LLC + * + * This driver provides the ability to control GPIOs on the Chrome OS EC. + * There isn't any direction control, and setting values on GPIOs is only + * possible when the system is unlocked. + */ + +#include <linux/bitops.h> +#include <linux/device.h> +#include <linux/errno.h> +#include <linux/gpio/driver.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/platform_data/cros_ec_commands.h> +#include <linux/platform_data/cros_ec_proto.h> +#include <linux/platform_device.h> +#include <linux/property.h> +#include <linux/slab.h> + +/* Prefix all names to avoid collisions with EC <-> AP nets */ +static const char cros_ec_gpio_prefix[] = "EC:"; + +/* Setting gpios is only supported when the system is unlocked */ +static void cros_ec_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val) +{ + const char *name = gc->names[gpio] + strlen(cros_ec_gpio_prefix); + struct cros_ec_device *cros_ec = gpiochip_get_data(gc); + struct ec_params_gpio_set params = { + .val = val, + }; + int ret; + ssize_t copied; + + copied = strscpy(params.name, name, sizeof(params.name)); + if (copied < 0) + return; + + ret = cros_ec_cmd(cros_ec, 0, EC_CMD_GPIO_SET, ¶ms, + sizeof(params), NULL, 0); + if (ret < 0) + dev_err(gc->parent, "error setting gpio%d (%s) on EC: %d\n", gpio, name, ret); +} + +static int cros_ec_gpio_get(struct gpio_chip *gc, unsigned int gpio) +{ + const char *name = gc->names[gpio] + strlen(cros_ec_gpio_prefix); + struct cros_ec_device *cros_ec = gpiochip_get_data(gc); + struct ec_params_gpio_get params; + struct ec_response_gpio_get response; + int ret; + ssize_t copied; + + copied = strscpy(params.name, name, sizeof(params.name)); + if (copied < 0) + return -EINVAL; + + ret = cros_ec_cmd(cros_ec, 0, EC_CMD_GPIO_GET, ¶ms, + sizeof(params), &response, sizeof(response)); + if (ret < 0) { + dev_err(gc->parent, "error getting gpio%d (%s) on EC: %d\n", gpio, name, ret); + return ret; + } + + return response.val; +} + +#define CROS_EC_GPIO_INPUT BIT(8) +#define CROS_EC_GPIO_OUTPUT BIT(9) + +static int cros_ec_gpio_get_direction(struct gpio_chip *gc, unsigned int gpio) +{ + const char *name = gc->names[gpio] + strlen(cros_ec_gpio_prefix); + struct cros_ec_device *cros_ec = gpiochip_get_data(gc); + struct ec_params_gpio_get_v1 params = { + .subcmd = EC_GPIO_GET_INFO, + .get_info.index = gpio, + }; + struct ec_response_gpio_get_v1 response; + int ret; + + ret = cros_ec_cmd(cros_ec, 1, EC_CMD_GPIO_GET, ¶ms, + sizeof(params), &response, sizeof(response)); + if (ret < 0) { + dev_err(gc->parent, "error getting direction of gpio%d (%s) on EC: %d\n", gpio, name, ret); + return ret; + } + + if (response.get_info.flags & CROS_EC_GPIO_INPUT) + return GPIO_LINE_DIRECTION_IN; + + if (response.get_info.flags & CROS_EC_GPIO_OUTPUT) + return GPIO_LINE_DIRECTION_OUT; + + return -EINVAL; +} + +/* Query EC for all gpio line names */ +static int cros_ec_gpio_init_names(struct cros_ec_device *cros_ec, struct gpio_chip *gc) +{ + struct ec_params_gpio_get_v1 params = { + .subcmd = EC_GPIO_GET_INFO, + }; + struct ec_response_gpio_get_v1 response; + int ret, i; + /* EC may not NUL terminate */ + size_t name_len = strlen(cros_ec_gpio_prefix) + sizeof(response.get_info.name) + 1; + ssize_t copied; + const char **names; + char *str; + + names = devm_kcalloc(gc->parent, gc->ngpio, sizeof(*names), GFP_KERNEL); + if (!names) + return -ENOMEM; + gc->names = names; + + str = devm_kcalloc(gc->parent, gc->ngpio, name_len, GFP_KERNEL); + if (!str) + return -ENOMEM; + + /* Get gpio line names one at a time */ + for (i = 0; i < gc->ngpio; i++) { + params.get_info.index = i; + ret = cros_ec_cmd(cros_ec, 1, EC_CMD_GPIO_GET, ¶ms, + sizeof(params), &response, sizeof(response)); + if (ret < 0) { + dev_err_probe(gc->parent, ret, "error getting gpio%d info\n", i); + return ret; + } + + names[i] = str; + copied = scnprintf(str, name_len, "%s%s", cros_ec_gpio_prefix, + response.get_info.name); + if (copied < 0) + return copied; + + str += copied + 1; + } + + return 0; +} + +/* Query EC for number of gpios */ +static int cros_ec_gpio_ngpios(struct cros_ec_device *cros_ec) +{ + struct ec_params_gpio_get_v1 params = { + .subcmd = EC_GPIO_GET_COUNT, + }; + struct ec_response_gpio_get_v1 response; + int ret; + + ret = cros_ec_cmd(cros_ec, 1, EC_CMD_GPIO_GET, ¶ms, + sizeof(params), &response, sizeof(response)); + if (ret < 0) + return ret; + + return response.get_count.val; +} + +static int cros_ec_gpio_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct device *parent = dev->parent; + struct cros_ec_dev *ec_dev = dev_get_drvdata(parent); + struct cros_ec_device *cros_ec = ec_dev->ec_dev; + struct gpio_chip *gc; + int ngpios; + int ret; + + /* Use the fwnode from the protocol device, e.g. cros-ec-spi */ + device_set_node(dev, dev_fwnode(cros_ec->dev)); + + ngpios = cros_ec_gpio_ngpios(cros_ec); + if (ngpios < 0) { + dev_err_probe(dev, ngpios, "error getting gpio count\n"); + return ngpios; + } + + gc = devm_kzalloc(dev, sizeof(*gc), GFP_KERNEL); + if (!gc) + return -ENOMEM; + + gc->ngpio = ngpios; + gc->parent = dev; + ret = cros_ec_gpio_init_names(cros_ec, gc); + if (ret) + return ret; + + gc->can_sleep = true; + gc->label = dev_name(dev); + gc->base = -1; + gc->set = cros_ec_gpio_set; + gc->get = cros_ec_gpio_get; + gc->get_direction = cros_ec_gpio_get_direction; + + return devm_gpiochip_add_data(dev, gc, cros_ec); +} + +static struct platform_driver cros_ec_gpio_driver = { + .probe = cros_ec_gpio_probe, + .driver = { + .name = "cros-ec-gpio", + }, +}; +module_platform_driver(cros_ec_gpio_driver); + +MODULE_DESCRIPTION("ChromeOS EC GPIO Driver"); +MODULE_LICENSE("GPL"); |