x86: geode: New PCEngines Alix system driver

This new driver replaces the old PCEngines Alix 2/3 LED driver with a
new driver that controls the LEDs through the leds-gpio driver. The
old driver accessed GPIOs directly, which created a conflict and
prevented also loading the cs5535-gpio driver to read other GPIOs on
the Alix board. With this new driver, we hook into leds-gpio which in
turn uses GPIO to control the LEDs and therefore it's possible to
control both the LEDs and access onboard GPIOs

Driver is moved to platform/geode as requested by Grant and any other
geode initialisation modules should move here also

This driver is inspired by leds-net5501.c by Alessandro Zummo.

Ideally, leds-net5501.c should also be moved to platform/geode. 
Additionally the driver relies on parts of the patch: 7f131cf3ed ("leds:
leds-alix2c - take port address from MSR) by Daniel Mack to perform
detection of the Alix board.

[akpm@linux-foundation.org: include module.h]

Signed-off-by: Ed Wildgoose <kernel@wildgooses.com>
Cc: git@wildgooses.com
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Daniel Mack <daniel@caiaq.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Reviewed-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/platform/Makefile

@@ -1,6 +1,7 @@
 # Platform specific code goes here
 obj-y	+= ce4100/
 obj-y	+= efi/
+obj-y	+= geode/
 obj-y	+= iris/
 obj-y	+= mrst/
 obj-y	+= olpc/

arch/x86/platform/geode/Makefile

@@ -0,0 +1 @@
+obj-$(CONFIG_ALIX)		+= alix.o

arch/x86/platform/geode/alix.c

@@ -0,0 +1,142 @@
+/*
+ * 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>
+ *
+ * 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
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/string.h>
+#include <linux/module.h>
+#include <linux/leds.h>
+#include <linux/platform_device.h>
+#include <linux/gpio.h>
+
+#include <asm/geode.h>
+
+static int 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 struct gpio_led alix_leds[] = {
+	{
+		.name = "alix:1",
+		.gpio = 6,
+		.default_trigger = "default-on",
+		.active_low = 1,
+	},
+	{
+		.name = "alix:2",
+		.gpio = 25,
+		.default_trigger = "default-off",
+		.active_low = 1,
+	},
+	{
+		.name = "alix:3",
+		.gpio = 27,
+		.default_trigger = "default-off",
+		.active_low = 1,
+	},
+};
+
+static struct gpio_led_platform_data alix_leds_data = {
+	.num_leds = ARRAY_SIZE(alix_leds),
+	.leds = alix_leds,
+};
+
+static struct platform_device alix_leds_dev = {
+	.name = "leds-gpio",
+	.id = -1,
+	.dev.platform_data = &alix_leds_data,
+};
+
+static void __init register_alix(void)
+{
+	/* Setup LED control through leds-gpio driver */
+	platform_device_register(&alix_leds_dev);
+}
+
+static int __init alix_present(unsigned long bios_phys,
+				const char *alix_sig,
+				size_t alix_sig_len)
+{
+	const size_t bios_len = 0x00010000;
+	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 1;
+	}
+
+	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')) {
+			printk(KERN_INFO
+			       "%s: system is recognized as \"%s\"\n",
+			       KBUILD_MODNAME, name);
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+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(0xf0000, tinybios_sig, sizeof(tinybios_sig) - 1) ||
+	    alix_present(0x500, coreboot_sig, sizeof(coreboot_sig) - 1))
+		register_alix();
+
+	return 0;
+}
+
+module_init(alix_init);
+
+MODULE_AUTHOR("Ed Wildgoose <kernel@wildgooses.com>");
+MODULE_DESCRIPTION("PCEngines ALIX System Setup");
+MODULE_LICENSE("GPL");