system76-coreboot/src/drivers/i2c/generic/generic.c

/* SPDX-License-Identifier: GPL-2.0-only */

#include <acpi/acpi_device.h>
#include <acpi/acpigen.h>
#include <console/console.h>
#include <device/i2c_bus.h>
#include <device/i2c_simple.h>
#include <device/device.h>
#include <device/path.h>
#include <gpio.h>
#include <string.h>
#include "chip.h"

#if CONFIG(HAVE_ACPI_TABLES)

static bool i2c_generic_add_gpios_to_crs(struct drivers_i2c_generic_config *cfg)
{
	/*
	 * Return false if:
	 * 1. Request to explicitly disable export of GPIOs in CRS, or
	 * 2. Both reset and enable GPIOs are not provided.
	 */
	if (cfg->disable_gpio_export_in_crs ||
	    ((cfg->reset_gpio.pin_count == 0) &&
	     (cfg->enable_gpio.pin_count == 0)))
		return false;

	return true;
}

static int i2c_generic_write_gpio(struct acpi_gpio *gpio, int *curr_index)
{
	int ret = -1;

	if (gpio->pin_count == 0)
		return ret;

	acpi_device_write_gpio(gpio);
	ret = *curr_index;
	(*curr_index)++;

	return ret;
}

void i2c_generic_fill_ssdt(const struct device *dev,
			void (*callback)(const struct device *dev),
			struct drivers_i2c_generic_config *config)
{
	const char *scope = acpi_device_scope(dev);
	struct acpi_i2c i2c = {
		.address = dev->path.i2c.device,
		.mode_10bit = dev->path.i2c.mode_10bit,
		.speed = config->speed ? : I2C_SPEED_FAST,
		.resource = scope,
	};
	struct acpi_dp *dsd = NULL;
	int curr_index = 0;
	int reset_gpio_index = -1, enable_gpio_index = -1, irq_gpio_index = -1;
	const char *path = acpi_device_path(dev);

	if (!scope)
		return;

	if (!config->hid) {
		printk(BIOS_ERR, "%s: HID required but not set\n", dev_path(dev));
		return;
	}

	if (config->detect) {
		struct device *const busdev = i2c_busdev(dev);
		if (!i2c_dev_detect(busdev, dev->path.i2c.device)) {
			printk(BIOS_SPEW, "%s: %s at %s -- NOT FOUND, skipping\n",
				path,
				config->desc ? : dev->chip_ops->name,
				dev_path(dev));
			return;
		}
	}

	if (config->has_power_resource && !config->disable_gpio_export_in_crs) {
		/*
		 * This case will most likely cause timing problems. The OS driver might be
		 * controlling the GPIOs, but the ACPI Power Resource will also be controlling
		 * them. This will result in the two fighting and stomping on each other.
		 */
		printk(BIOS_ERR, "%s: Exposing GPIOs in Power Resource and _CRS\n",
		       dev_path(dev));
	}

	/* Device */
	acpigen_write_scope(scope);
	acpigen_write_device(acpi_device_name(dev));
	acpigen_write_name_string("_HID", config->hid);
	if (config->cid)
		acpigen_write_name_string("_CID", config->cid);
	acpigen_write_name_integer("_UID", config->uid);
	if (config->desc)
		acpigen_write_name_string("_DDN", config->desc);
	acpigen_write_STA(acpi_device_status(dev));

	/* Resources */
	acpigen_write_name("_CRS");
	acpigen_write_resourcetemplate_header();
	acpi_device_write_i2c(&i2c);

	/* Use either Interrupt() or GpioInt() */
	if (config->irq_gpio.pin_count)
		irq_gpio_index = i2c_generic_write_gpio(&config->irq_gpio,
							&curr_index);
	else
		acpi_device_write_interrupt(&config->irq);

	if (i2c_generic_add_gpios_to_crs(config) == true) {
		reset_gpio_index = i2c_generic_write_gpio(&config->reset_gpio,
							&curr_index);
		enable_gpio_index = i2c_generic_write_gpio(&config->enable_gpio,
							&curr_index);
	}
	acpigen_write_resourcetemplate_footer();

	/* Wake capabilities */
	if (config->wake) {
		acpigen_write_name_integer("_S0W", ACPI_DEVICE_SLEEP_D3_HOT);
		acpigen_write_PRW(config->wake, 3);
	}

	/* DSD */
	if (config->probed || config->property_count || config->compat_string ||
	    (reset_gpio_index != -1) ||
	    (enable_gpio_index != -1) || (irq_gpio_index != -1)) {
		dsd = acpi_dp_new_table("_DSD");
		if (config->compat_string)
			acpi_dp_add_string(dsd, "compatible",
					   config->compat_string);
		if (config->probed)
			acpi_dp_add_integer(dsd, "linux,probed", 1);
		if (irq_gpio_index != -1)
			acpi_dp_add_gpio(dsd, "irq-gpios", path,
					 irq_gpio_index, 0,
					 config->irq_gpio.active_low);
		if (reset_gpio_index != -1)
			acpi_dp_add_gpio(dsd, "reset-gpios", path,
					reset_gpio_index, 0,
					config->reset_gpio.active_low);
		if (enable_gpio_index != -1)
			acpi_dp_add_gpio(dsd, "enable-gpios", path,
					enable_gpio_index, 0,
					config->enable_gpio.active_low);
		/* Add generic property list */
		acpi_dp_add_property_list(dsd, config->property_list,
					  config->property_count);
		acpi_dp_write(dsd);
	}

	/* Power Resource */
	if (config->has_power_resource) {
		const struct acpi_power_res_params power_res_params = {
			&config->reset_gpio,
			config->reset_delay_ms,
			config->reset_off_delay_ms,
			&config->enable_gpio,
			config->enable_delay_ms,
			config->enable_off_delay_ms,
			&config->stop_gpio,
			config->stop_delay_ms,
			config->stop_off_delay_ms
		};
		acpi_device_add_power_res(&power_res_params);
	}

	/* Callback if any. */
	if (callback)
		callback(dev);

	acpigen_pop_len(); /* Device */
	acpigen_pop_len(); /* Scope */

	printk(BIOS_INFO, "%s: %s at %s\n", path,
	       config->desc ? : dev->chip_ops->name, dev_path(dev));
}

static void i2c_generic_fill_ssdt_generator(const struct device *dev)
{
	i2c_generic_fill_ssdt(dev, NULL, dev->chip_info);
}

/* Use name specified in config or build one from I2C address */
static const char *i2c_generic_acpi_name(const struct device *dev)
{
	struct drivers_i2c_generic_config *config = dev->chip_info;
	static char name[5];

	if (config->name)
		return config->name;

	snprintf(name, sizeof(name), "D%03.3X", dev->path.i2c.device);
	name[4] = '\0';
	return name;
}
#endif

static struct device_operations i2c_generic_ops = {
	.read_resources		= noop_read_resources,
	.set_resources		= noop_set_resources,
#if CONFIG(HAVE_ACPI_TABLES)
	.acpi_name		= i2c_generic_acpi_name,
	.acpi_fill_ssdt		= i2c_generic_fill_ssdt_generator,
#endif
};

static void i2c_generic_enable(struct device *dev)
{
	struct drivers_i2c_generic_config *config = dev->chip_info;

	if (!config)
		return;

	/* Check if device is present by reading GPIO */
	if (config->device_present_gpio) {
		int present = gpio_get(config->device_present_gpio);
		present ^= config->device_present_gpio_invert;

		printk(BIOS_INFO, "%s is %spresent\n",
		       dev->chip_ops->name, present ? "" : "not ");

		if (!present) {
			dev->enabled = 0;
			return;
		}
	}

	dev->ops = &i2c_generic_ops;

	/* Name the device as per description provided in devicetree */
	if (config->desc)
		dev->name = config->desc;
}

struct chip_operations drivers_i2c_generic_ops = {
	CHIP_NAME("I2C Device")
	.enable_dev = i2c_generic_enable
};