linux/arch/x86/platform/geode/alix.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * System Specific setup for PCEngines ALIX.
 * At the moment this means setup of GPIO control of LEDs
 * on Alix.2/3/6 boards.
 *
 * Copyright (C) 2008 Constantin Baranov <const@mimas.ru>
 * Copyright (C) 2011 Ed Wildgoose <kernel@wildgooses.com>
 *                and Philip Prindeville <philipp@redfish-solutions.com>
 *
 * TODO: There are large similarities with leds-net5501.c
 * by Alessandro Zummo <a.zummo@towertech.it>
 * In the future leds-net5501.c should be migrated over to platform
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/string.h>
#include <linux/moduleparam.h>
#include <linux/dmi.h>

#include <asm/geode.h>

#include "geode-common.h"

#define BIOS_SIGNATURE_TINYBIOS		0xf0000
#define BIOS_SIGNATURE_COREBOOT		0x500
#define BIOS_REGION_SIZE		0x10000

/*
 * This driver is not modular, but to keep back compatibility
 * with existing use cases, continuing with module_param is
 * the easiest way forward.
 */
static bool force = 0;
module_param(force, bool, 0444);
/* FIXME: Award bios is not automatically detected as Alix platform */
MODULE_PARM_DESC(force, "Force detection as ALIX.2/ALIX.3 platform");

static const struct geode_led alix_leds[] __initconst = {
	{ 6, true },
	{ 25, false },
	{ 27, false },
};

static void __init register_alix(void)
{
	geode_create_restart_key(24);
	geode_create_leds("alix", alix_leds, ARRAY_SIZE(alix_leds));
}

static bool __init alix_present(unsigned long bios_phys,
				const char *alix_sig,
				size_t alix_sig_len)
{
	const size_t bios_len = BIOS_REGION_SIZE;
	const char *bios_virt;
	const char *scan_end;
	const char *p;
	char name[64];

	if (force) {
		printk(KERN_NOTICE "%s: forced to skip BIOS test, "
		       "assume system is ALIX.2/ALIX.3\n",
		       KBUILD_MODNAME);
		return true;
	}

	bios_virt = phys_to_virt(bios_phys);
	scan_end = bios_virt + bios_len - (alix_sig_len + 2);
	for (p = bios_virt; p < scan_end; p++) {
		const char *tail;
		char *a;

		if (memcmp(p, alix_sig, alix_sig_len) != 0)
			continue;

		memcpy(name, p, sizeof(name));

		/* remove the first \0 character from string */
		a = strchr(name, '\0');
		if (a)
			*a = ' ';

		/* cut the string at a newline */
		a = strchr(name, '\r');
		if (a)
			*a = '\0';

		tail = p + alix_sig_len;
		if ((tail[0] == '2' || tail[0] == '3' || tail[0] == '6')) {
			printk(KERN_INFO
			       "%s: system is recognized as \"%s\"\n",
			       KBUILD_MODNAME, name);
			return true;
		}
	}

	return false;
}

static bool __init alix_present_dmi(void)
{
	const char *vendor, *product;

	vendor = dmi_get_system_info(DMI_SYS_VENDOR);
	if (!vendor || strcmp(vendor, "PC Engines"))
		return false;

	product = dmi_get_system_info(DMI_PRODUCT_NAME);
	if (!product || (strcmp(product, "ALIX.2D") && strcmp(product, "ALIX.6")))
		return false;

	printk(KERN_INFO "%s: system is recognized as \"%s %s\"\n",
	       KBUILD_MODNAME, vendor, product);

	return true;
}

static int __init alix_init(void)
{
	const char tinybios_sig[] = "PC Engines ALIX.";
	const char coreboot_sig[] = "PC Engines\0ALIX.";

	if (!is_geode())
		return 0;

	if (alix_present(BIOS_SIGNATURE_TINYBIOS, tinybios_sig, sizeof(tinybios_sig) - 1) ||
	    alix_present(BIOS_SIGNATURE_COREBOOT, coreboot_sig, sizeof(coreboot_sig) - 1) ||
	    alix_present_dmi())
		register_alix();

	return 0;
}
device_initcall(alix_init);