drivers/platform/chrome/chromeos_pstore.c

// SPDX-License-Identifier: GPL-2.0
// Driver to instantiate Chromebook ramoops device.
//
// Copyright (C) 2013 Google, Inc.

#include <linux/acpi.h>
#include <linux/dmi.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pstore_ram.h>

static const struct dmi_system_id chromeos_pstore_dmi_table[] __initconst = {
	{
		/*
		 * Today all Chromebooks/boxes ship with Google_* as version and
		 * coreboot as bios vendor. No other systems with this
		 * combination are known to date.
		 */
		.matches = {
			DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
			DMI_MATCH(DMI_BIOS_VERSION, "Google_"),
		},
	},
	{
		/* x86-alex, the first Samsung Chromebook. */
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
			DMI_MATCH(DMI_PRODUCT_NAME, "Alex"),
		},
	},
	{
		/* x86-mario, the Cr-48 pilot device from Google. */
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "IEC"),
			DMI_MATCH(DMI_PRODUCT_NAME, "Mario"),
		},
	},
	{
		/* x86-zgb, the first Acer Chromebook. */
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "ACER"),
			DMI_MATCH(DMI_PRODUCT_NAME, "ZGB"),
		},
	},
	{ }
};
MODULE_DEVICE_TABLE(dmi, chromeos_pstore_dmi_table);

/*
 * On x86 chromebooks/boxes, the firmware will keep the legacy VGA memory
 * range untouched across reboots, so we use that to store our pstore
 * contents for panic logs, etc.
 */
static struct ramoops_platform_data chromeos_ramoops_data = {
	.mem_size	= 0x100000,
	.mem_address	= 0xf00000,
	.record_size	= 0x40000,
	.console_size	= 0x20000,
	.ftrace_size	= 0x20000,
	.pmsg_size	= 0x20000,
	.max_reason	= KMSG_DUMP_OOPS,
};

static struct platform_device chromeos_ramoops = {
	.name = "ramoops",
	.dev = {
		.platform_data = &chromeos_ramoops_data,
	},
};

#ifdef CONFIG_ACPI
static const struct acpi_device_id cros_ramoops_acpi_match[] = {
	{ "GOOG9999", 0 },
	{ }
};
MODULE_DEVICE_TABLE(acpi, cros_ramoops_acpi_match);

static struct platform_driver chromeos_ramoops_acpi = {
	.driver		= {
		.name	= "chromeos_pstore",
		.acpi_match_table = ACPI_PTR(cros_ramoops_acpi_match),
	},
};

static int __init chromeos_probe_acpi(struct platform_device *pdev)
{
	struct resource *res;
	resource_size_t len;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res)
		return -ENOMEM;

	len = resource_size(res);
	if (!res->start || !len)
		return -ENOMEM;

	pr_info("chromeos ramoops using acpi device.\n");

	chromeos_ramoops_data.mem_size = len;
	chromeos_ramoops_data.mem_address = res->start;

	return 0;
}

static bool __init chromeos_check_acpi(void)
{
	if (!platform_driver_probe(&chromeos_ramoops_acpi, chromeos_probe_acpi))
		return true;
	return false;
}
#else
static inline bool chromeos_check_acpi(void) { return false; }
#endif

static int __init chromeos_pstore_init(void)
{
	bool acpi_dev_found;

	/* First check ACPI for non-hardcoded values from firmware. */
	acpi_dev_found = chromeos_check_acpi();

	if (acpi_dev_found || dmi_check_system(chromeos_pstore_dmi_table))
		return platform_device_register(&chromeos_ramoops);

	return -ENODEV;
}

static void __exit chromeos_pstore_exit(void)
{
	platform_device_unregister(&chromeos_ramoops);
}

module_init(chromeos_pstore_init);
module_exit(chromeos_pstore_exit);

MODULE_DESCRIPTION("ChromeOS pstore module");
MODULE_LICENSE("GPL v2");