Samsung N130 ATA exception after 5min uptime -- Phoenix FailSafeissue?

[Johannes Stezenbach]

Hi,

I'm refering to
http://bugzilla.kernel.org/show_bug.cgi?id=14314
and I still have this issue on a N130 with latest BIOS (05CM),
running kernel 2.6.32-rc8 + wireless-testing.

BIOS Information
        Vendor: Phoenix Technologies Ltd.
        Version: 05CM.M011.20091013.JIP
        Release Date: 10/13/2009
        Address: 0xE6300
        Runtime Size: 105728 bytes
        ROM Size: 2048 kB
        Characteristics:
                ISA is supported
                PCI is supported
                PNP is supported
                BIOS is upgradeable
                BIOS shadowing is allowed
                ESCD support is available
                ACPI is supported
                USB legacy is supported
                Smart battery is supported
                BIOS boot specification is supported
                Targeted content distribution is supported
        BIOS Revision: 5.0

Around 5min after boot or resume if generates the following error:

[  302.364174] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
[  302.364201] ata1.00: failed command: WRITE DMA
[  302.364234] ata1.00: cmd ca/00:08:f7:01:1a/00:00:00:00:00/e0 tag 0 dma 4096 out
[  302.364241]          res 40/00:00:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[  302.364257] ata1.00: status: { DRDY }
[  307.408107] ata1: link is slow to respond, please be patient (ready=0)
[  312.392109] ata1: device not ready (errno=-16), forcing hardreset
[  312.392138] ata1: soft resetting link
[  312.574482] ata1.00: configured for UDMA/133
[  312.574506] ata1.00: device reported invalid CHS sector 0
[  312.574542] ata1: EH complete

This also happens when booting with rdinit=/bin/sh, i.e. only running busybox sh
inside initrd.  The error then appears when accessing the disk after the 5min
period with dd if=/dev/sda of=/dev/null count=10000.


The link in comment #14 is dead but eventually I found
http://download.opensuse.org/repositories/Moblin:/Base/openSUSE_11.1/src/kernel-source-2.6.31.6-37.1.src.rpm
which contains the attached patch with a samsung_laptop driver.

I think it is weird that the Samsung BIOS has a special "SECLINUX" mode,
but anyway the samsung_laptop driver works (the backlight control via ACPI
also works with the 05CM BIOS, though).

However, it does not prevent the ATA exception.

(Side note about backlight level 0: I noticed that in Windows when you
set the backlight to the lowest level, after a minute of inactivity
the screen would dim one level more. Stupid -- why not allow the user
to choose that level manually?)

So I guess one really needs the special Linux BIOS that Greg was talking
about in comments #14 and #16?  It is not clear from comment #17
which BIOS worked for Mikhail.

Or did I just miss some patch or magic config setting?


According to $subject, I have a wild theory that the issue
might be caused by the Phoenix "FailSafe" BIOS feature.
first of all, there is no indication on Samsung's web pages
anywhere that the N130 has it, but I had looked at the pre-installed
Windows before I wiped it (and did the BIOS update while at it),
and it had a "Phoenix FailSafe" icon prominently placed on the desktop.
Some searching yields:
http://www.failsafe.com/samsung-partner-profile

And after some more searching:
http://www.blackhat.com/presentations/bh-usa-09/ORTEGA/BHUSA09-Ortega-DeactivateRootkit-PAPER.pdf
which is about Computrace which appears to be a similar technology.

What I think is what happens is that the BIOS waits to be contacted
by the Windows "FailSafe" agent, and if that doesn't happen then the BIOS
tries to reinstall the agent into the Windows installation. Thus it
accesses the disk behind the OS's back, and this causes the ATA exception.
When FailSafe isn't activated by the user then the BIOS shouldn't do that,
but the BIOS developers might have thought different...

Note however that the BIOS setup screen contains no indication about FailSafe
support, so this is all wild guessing. It would fit in with the "special
Linux BIOS" info, though.  But I had hoped that the "SECLINUX" mode
would also disable it.


Thanks
Johannes
>From foo@baz Fri Aug 21 15:51:53 PDT 2009
Date: Fri, 21 Aug 2009 15:51:53 -0700
To: Greg KH <greg@xxxxxxxxx>
From: Greg Kroah-Hartman <gregkh@xxxxxxx>
Subject: Samsung laptop driver

This driver implements backlight controls for Samsung laptops that
currently do not have ACPI support for this control.

It has been tested on the N130 laptop and properly works there.

Info for the NC10 was provided by Soeren Sonnenburg <bugreports@xxxxxx>
Info for the NP-Q45 from Jérémie Huchet <jeremie@xxxxxxxxxx>

Many thanks to Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> for cleanups
and other suggestions on how to make the driver simpler.

Cc: Soeren Sonnenburg <bugreports@xxxxxx>
Cc: Jérémie Huchet <jeremie@xxxxxxxxxx>
Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/platform/x86/Kconfig          |   12 
 drivers/platform/x86/Makefile         |    1 
 drivers/platform/x86/samsung-laptop.c |  582 ++++++++++++++++++++++++++++++++++
 3 files changed, 595 insertions(+)


--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -425,4 +425,16 @@ config ACPI_TOSHIBA
 
 	  If you have a legacy free Toshiba laptop (such as the Libretto L1
 	  series), say Y.
+
+config SAMSUNG_LAPTOP
+	tristate "Samsung Laptop driver"
+	depends on BACKLIGHT_CLASS_DEVICE
+	depends on DMI
+	---help---
+	  This driver adds support to control the backlight on a number of
+	  Samsung laptops, like the N130, and control for some of the LEDs
+
+	  It will only be loaded on laptops that properly need it, so it is
+	  safe to say Y here.
+
 endif # X86_PLATFORM_DEVICES
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -20,3 +20,4 @@ obj-$(CONFIG_INTEL_MENLOW)	+= intel_menl
 obj-$(CONFIG_ACPI_WMI)		+= wmi.o
 obj-$(CONFIG_ACPI_ASUS)		+= asus_acpi.o
 obj-$(CONFIG_ACPI_TOSHIBA)	+= toshiba_acpi.o
+obj-$(CONFIG_SAMSUNG_LAPTOP)	+= samsung-laptop.o
--- /dev/null
+++ b/drivers/platform/x86/samsung-laptop.c
@@ -0,0 +1,582 @@
+/*
+ * Samsung N130 Laptop driver
+ *
+ * Copyright (C) 2009 Greg Kroah-Hartman (gregkh@xxxxxxx)
+ * Copyright (C) 2009 Novell Inc.
+ *
+ * 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/version.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/pci.h>
+#include <linux/backlight.h>
+#include <linux/fb.h>
+#include <linux/dmi.h>
+#include <linux/platform_device.h>
+#include <linux/rfkill.h>
+
+/*
+ * This driver is needed because a number of Samsung laptops do not hook
+ * their control settings through ACPI.  So we have to poke around in the
+ * BIOS to do things like brightness values, and "special" key controls.
+ */
+
+/*
+ * We have 0 - 8 as valid brightness levels.  The specs say that level 0 should
+ * be reserved by the BIOS (which really doesn't make much sense), we tell
+ * userspace that the value is 0 - 7 and then just tell the hardware 1 - 8
+ */
+#define MAX_BRIGHT	0x07
+
+/* Brightness is 0 - 8, as described above.  Value 0 is for the BIOS to use */
+#define GET_BRIGHTNESS			0x00
+#define SET_BRIGHTNESS			0x01
+
+/* first byte:
+ * 0x00 - wireless is off
+ * 0x01 - wireless is on
+ * second byte:
+ * 0x02 - 3G is off
+ * 0x03 - 3G is on
+ * TODO, verify 3G is correct, that doesn't seem right...
+ */
+#define GET_WIRELESS_BUTTON		0x02
+#define SET_WIRELESS_BUTTON		0x03
+
+/* 0 is off, 1 is on */
+#define GET_BACKLIGHT			0x04
+#define SET_BACKLIGHT			0x05
+
+/*
+ * 0x80 or 0x00 - no action
+ * 0x81 - recovery key pressed
+ */
+#define GET_RECOVERY_METHOD		0x06
+#define SET_RECOVERY_METHOD		0x07
+
+/* 0 is low, 1 is high */
+#define GET_PERFORMANCE_LEVEL		0x08
+#define SET_PERFORMANCE_LEVEL		0x09
+
+/*
+ * Tell the BIOS that Linux is running on this machine.
+ * 81 is on, 80 is off
+ */
+#define SET_LINUX			0x0a
+
+
+#define MAIN_FUNCTION			0x4c49
+
+#define SABI_HEADER_PORT		0x00
+#define SABI_HEADER_RE_MEM		0x02
+#define SABI_HEADER_IFACEFUNC		0x03
+#define SABI_HEADER_EN_MEM		0x04
+#define SABI_HEADER_DATA_OFFSET		0x05
+#define SABI_HEADER_DATA_SEGMENT	0x07
+
+#define SABI_IFACE_MAIN			0x00
+#define SABI_IFACE_SUB			0x02
+#define SABI_IFACE_COMPLETE		0x04
+#define SABI_IFACE_DATA			0x05
+
+/* Structure to get data back to the calling function */
+struct sabi_retval {
+	u8 retval[20];
+};
+
+static void __iomem *sabi;
+static void __iomem *sabi_iface;
+static void __iomem *f0000_segment;
+static struct backlight_device *backlight_device;
+static struct mutex sabi_mutex;
+static struct platform_device *sdev;
+static struct rfkill *rfk;
+
+static int force;
+module_param(force, bool, 0);
+MODULE_PARM_DESC(force, "Disable the DMI check and forces the driver to be loaded");
+
+static int debug;
+module_param(debug, bool, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(debug, "Debug enabled or not");
+
+static int sabi_get_command(u8 command, struct sabi_retval *sretval)
+{
+	int retval = 0;
+	u16 port = readw(sabi + SABI_HEADER_PORT);
+
+	mutex_lock(&sabi_mutex);
+
+	/* enable memory to be able to write to it */
+	outb(readb(sabi + SABI_HEADER_EN_MEM), port);
+
+	/* write out the command */
+	writew(MAIN_FUNCTION, sabi_iface + SABI_IFACE_MAIN);
+	writew(command, sabi_iface + SABI_IFACE_SUB);
+	writeb(0, sabi_iface + SABI_IFACE_COMPLETE);
+	outb(readb(sabi + SABI_HEADER_IFACEFUNC), port);
+
+	/* write protect memory to make it safe */
+	outb(readb(sabi + SABI_HEADER_RE_MEM), port);
+
+	/* see if the command actually succeeded */
+	if (readb(sabi_iface + SABI_IFACE_COMPLETE) == 0xaa &&
+	    readb(sabi_iface + SABI_IFACE_DATA) != 0xff) {
+		/*
+		 * It did!
+		 * Save off the data into a structure so the caller use it.
+		 * Right now we only care about the first 4 bytes,
+		 * I suppose there are commands that need more, but I don't
+		 * know about them.
+		 */
+		sretval->retval[0] = readb(sabi_iface + SABI_IFACE_DATA);
+		sretval->retval[1] = readb(sabi_iface + SABI_IFACE_DATA + 1);
+		sretval->retval[2] = readb(sabi_iface + SABI_IFACE_DATA + 2);
+		sretval->retval[3] = readb(sabi_iface + SABI_IFACE_DATA + 3);
+		goto exit;
+	}
+
+	/* Something bad happened, so report it and error out */
+	printk(KERN_WARNING "SABI command 0x%02x failed with completion flag 0x%02x and output 0x%02x\n",
+		command, readb(sabi_iface + SABI_IFACE_COMPLETE),
+		readb(sabi_iface + SABI_IFACE_DATA));
+	retval = -EINVAL;
+exit:
+	mutex_unlock(&sabi_mutex);
+	return retval;
+
+}
+
+static int sabi_set_command(u8 command, u8 data)
+{
+	int retval = 0;
+	u16 port = readw(sabi + SABI_HEADER_PORT);
+
+	mutex_lock(&sabi_mutex);
+
+	/* enable memory to be able to write to it */
+	outb(readb(sabi + SABI_HEADER_EN_MEM), port);
+
+	/* write out the command */
+	writew(MAIN_FUNCTION, sabi_iface + SABI_IFACE_MAIN);
+	writew(command, sabi_iface + SABI_IFACE_SUB);
+	writeb(0, sabi_iface + SABI_IFACE_COMPLETE);
+	writeb(data, sabi_iface + SABI_IFACE_DATA);
+	outb(readb(sabi + SABI_HEADER_IFACEFUNC), port);
+
+	/* write protect memory to make it safe */
+	outb(readb(sabi + SABI_HEADER_RE_MEM), port);
+
+	/* see if the command actually succeeded */
+	if (readb(sabi_iface + SABI_IFACE_COMPLETE) == 0xaa &&
+	    readb(sabi_iface + SABI_IFACE_DATA) != 0xff) {
+		/* it did! */
+		goto exit;
+	}
+
+	/* Something bad happened, so report it and error out */
+	printk(KERN_WARNING "SABI command 0x%02x failed with completion flag 0x%02x and output 0x%02x\n",
+		command, readb(sabi_iface + SABI_IFACE_COMPLETE),
+		readb(sabi_iface + SABI_IFACE_DATA));
+	retval = -EINVAL;
+exit:
+	mutex_unlock(&sabi_mutex);
+	return retval;
+}
+
+static void test_backlight(void)
+{
+	struct sabi_retval sretval;
+
+	sabi_get_command(GET_BACKLIGHT, &sretval);
+	printk(KERN_DEBUG "backlight = 0x%02x\n", sretval.retval[0]);
+
+	sabi_set_command(SET_BACKLIGHT, 0);
+	printk(KERN_DEBUG "backlight should be off\n");
+
+	sabi_get_command(GET_BACKLIGHT, &sretval);
+	printk(KERN_DEBUG "backlight = 0x%02x\n", sretval.retval[0]);
+
+	msleep(1000);
+
+	sabi_set_command(SET_BACKLIGHT, 1);
+	printk(KERN_DEBUG "backlight should be on\n");
+
+	sabi_get_command(GET_BACKLIGHT, &sretval);
+	printk(KERN_DEBUG "backlight = 0x%02x\n", sretval.retval[0]);
+}
+
+static void test_wireless(void)
+{
+	struct sabi_retval sretval;
+
+	sabi_get_command(GET_WIRELESS_BUTTON, &sretval);
+	printk(KERN_DEBUG "wireless led = 0x%02x\n", sretval.retval[0]);
+
+	sabi_set_command(SET_WIRELESS_BUTTON, 0);
+	printk(KERN_DEBUG "wireless led should be off\n");
+
+	sabi_get_command(GET_WIRELESS_BUTTON, &sretval);
+	printk(KERN_DEBUG "wireless led = 0x%02x\n", sretval.retval[0]);
+
+	msleep(1000);
+
+	sabi_set_command(SET_WIRELESS_BUTTON, 1);
+	printk(KERN_DEBUG "wireless led should be on\n");
+
+	sabi_get_command(GET_WIRELESS_BUTTON, &sretval);
+	printk(KERN_DEBUG "wireless led = 0x%02x\n", sretval.retval[0]);
+}
+
+static u8 read_brightness(void)
+{
+	struct sabi_retval sretval;
+	int user_brightness = 0;
+	int retval;
+
+	retval = sabi_get_command(GET_BACKLIGHT, &sretval);
+	if (!retval)
+		user_brightness = sretval.retval[0];
+		if (user_brightness != 0)
+			--user_brightness;
+	return user_brightness;
+}
+
+static void set_brightness(u8 user_brightness)
+{
+	sabi_set_command(SET_BRIGHTNESS, user_brightness + 1);
+}
+
+static int get_brightness(struct backlight_device *bd)
+{
+	return bd->props.brightness;
+}
+
+static int update_status(struct backlight_device *bd)
+{
+	set_brightness(bd->props.brightness);
+
+	if (bd->props.power == FB_BLANK_UNBLANK)
+		sabi_set_command(SET_BACKLIGHT, 1);
+	else
+		sabi_set_command(SET_BACKLIGHT, 0);
+	return 0;
+}
+
+static struct backlight_ops backlight_ops = {
+	.get_brightness	= get_brightness,
+	.update_status	= update_status,
+};
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,31)
+static int rfkill_set(void *data, bool blocked)
+{
+	/* Do something with blocked...*/
+	/*
+	 * blocked == false is on
+	 * blocked == true is off
+	 */
+	if (blocked)
+		sabi_set_command(SET_WIRELESS_BUTTON, 0);
+	else
+		sabi_set_command(SET_WIRELESS_BUTTON, 1);
+
+	return 0;
+}
+
+static struct rfkill_ops rfkill_ops = {
+	.set_block = rfkill_set,
+};
+
+static int init_wireless(struct platform_device *sdev)
+{
+	int retval;
+
+	rfk = rfkill_alloc("samsung-wifi", &sdev->dev, RFKILL_TYPE_WLAN,
+			   &rfkill_ops, NULL);
+	if (!rfk)
+		return -ENOMEM;
+
+	retval = rfkill_register(rfk);
+	if (retval) {
+		rfkill_destroy(rfk);
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static void destroy_wireless(void)
+{
+	rfkill_unregister(rfk);
+	rfkill_destroy(rfk);
+}
+
+#else
+
+static int rfkill_set(void *data, enum rfkill_state state)
+{
+	if (state ==  RFKILL_STATE_UNBLOCKED)
+		sabi_set_command(SET_WIRELESS_BUTTON, 1);
+	else
+		sabi_set_command(SET_WIRELESS_BUTTON, 0);
+
+	return 0;
+}
+
+static int init_wireless(struct platform_device *sdev)
+{
+	int retval;
+
+	rfk = rfkill_allocate(&sdev->dev, RFKILL_TYPE_WLAN);
+	if (!rfk)
+		return -ENOMEM;
+	rfk->toggle_radio = rfkill_set;
+	rfk->name = "samsung-wifi";
+
+	retval = rfkill_register(rfk);
+	if (retval) {
+		rfkill_free(rfk);
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static void destroy_wireless(void)
+{
+	rfkill_unregister(rfk);
+}
+
+#endif
+
+static ssize_t get_silent_state(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct sabi_retval sretval;
+	int retval;
+
+	/* Read the state */
+	retval = sabi_get_command(GET_PERFORMANCE_LEVEL, &sretval);
+	if (retval)
+		return retval;
+
+	/* The logic is backwards, yeah, lots of fun... */
+	if (sretval.retval[0] == 0)
+		retval = 1;
+	else
+		retval = 0;
+	return sprintf(buf, "%d\n", retval);
+}
+
+static ssize_t set_silent_state(struct device *dev,
+				struct device_attribute *attr, const char *buf,
+				size_t count)
+{
+	char value;
+
+	if (count >= 1) {
+		value = buf[0];
+		if ((value == '0') || (value == 'n') || (value == 'N')) {
+			/* Turn speed up */
+			sabi_set_command(SET_PERFORMANCE_LEVEL, 0x01);
+		} else if ((value == '1') || (value == 'y') || (value == 'Y')) {
+			/* Turn speed down */
+			sabi_set_command(SET_PERFORMANCE_LEVEL, 0x00);
+		} else {
+			return -EINVAL;
+		}
+	}
+	return count;
+}
+static DEVICE_ATTR(silent, S_IWUGO | S_IRUGO,
+		   get_silent_state, set_silent_state);
+
+
+static int __init dmi_check_cb(const struct dmi_system_id *id)
+{
+	printk(KERN_INFO KBUILD_MODNAME ": found laptop model '%s'\n",
+		id->ident);
+	return 0;
+}
+
+static struct dmi_system_id __initdata samsung_dmi_table[] = {
+	{
+		.ident = "N128",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "N128"),
+			DMI_MATCH(DMI_BOARD_NAME, "N128"),
+		},
+		.callback = dmi_check_cb,
+	},
+	{
+		.ident = "N130",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "N130"),
+			DMI_MATCH(DMI_BOARD_NAME, "N130"),
+		},
+		.callback = dmi_check_cb,
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(dmi, samsung_dmi_table);
+
+static int __init samsung_init(void)
+{
+	struct sabi_retval sretval;
+	const char *testStr = "SECLINUX";
+	void __iomem *memcheck;
+	unsigned int ifaceP;
+	int pStr;
+	int loca;
+	int retval;
+
+	mutex_init(&sabi_mutex);
+
+	if (!force && !dmi_check_system(samsung_dmi_table))
+		return -ENODEV;
+
+	f0000_segment = ioremap(0xf0000, 0xffff);
+	if (!f0000_segment) {
+		printk(KERN_ERR "Can't map the segment at 0xf0000\n");
+		return -EINVAL;
+	}
+
+	/* Try to find the signature "SECLINUX" in memory to find the header */
+	pStr = 0;
+	memcheck = f0000_segment;
+	for (loca = 0; loca < 0xffff; loca++) {
+		char temp = readb(memcheck + loca);
+
+		if (temp == testStr[pStr]) {
+			if (pStr == strlen(testStr)-1)
+				break;
+			++pStr;
+		} else {
+			pStr = 0;
+		}
+	}
+	if (loca == 0xffff) {
+		printk(KERN_ERR "This computer does not support SABI\n");
+		goto error_no_signature;
+		}
+
+	/* point to the SMI port Number */
+	loca += 1;
+	sabi = (memcheck + loca);
+
+	if (debug) {
+		printk(KERN_DEBUG "This computer supports SABI==%x\n",
+			loca + 0xf0000 - 6);
+		printk(KERN_DEBUG "SABI header:\n");
+		printk(KERN_DEBUG " SMI Port Number = 0x%04x\n",
+			readw(sabi + SABI_HEADER_PORT));
+		printk(KERN_DEBUG " SMI Interface Function = 0x%02x\n",
+			readb(sabi + SABI_HEADER_IFACEFUNC));
+		printk(KERN_DEBUG " SMI enable memory buffer = 0x%02x\n",
+			readb(sabi + SABI_HEADER_EN_MEM));
+		printk(KERN_DEBUG " SMI restore memory buffer = 0x%02x\n",
+			readb(sabi + SABI_HEADER_RE_MEM));
+		printk(KERN_DEBUG " SABI data offset = 0x%04x\n",
+			readw(sabi + SABI_HEADER_DATA_OFFSET));
+		printk(KERN_DEBUG " SABI data segment = 0x%04x\n",
+			readw(sabi + SABI_HEADER_DATA_SEGMENT));
+	}
+
+	/* Get a pointer to the SABI Interface */
+	ifaceP = (readw(sabi + SABI_HEADER_DATA_SEGMENT) & 0x0ffff) << 4;
+	ifaceP += readw(sabi + SABI_HEADER_DATA_OFFSET) & 0x0ffff;
+	sabi_iface = ioremap(ifaceP, 16);
+	if (!sabi_iface) {
+		printk(KERN_ERR "Can't remap %x\n", ifaceP);
+		goto exit;
+	}
+	if (debug) {
+		printk(KERN_DEBUG "ifaceP = 0x%08x\n", ifaceP);
+		printk(KERN_DEBUG "sabi_iface = %p\n", sabi_iface);
+
+		test_backlight();
+		test_wireless();
+
+		retval = sabi_get_command(GET_BRIGHTNESS, &sretval);
+		printk(KERN_DEBUG "brightness = 0x%02x\n", sretval.retval[0]);
+	}
+
+	/* Turn on "Linux" mode in the BIOS */
+	retval = sabi_set_command(SET_LINUX, 0x81);
+	if (retval) {
+		printk(KERN_ERR KBUILD_MODNAME ": Linux mode was not set!\n");
+		goto error_no_platform;
+	}
+
+	/* knock up a platform device to hang stuff off of */
+	sdev = platform_device_register_simple("samsung", -1, NULL, 0);
+	if (IS_ERR(sdev))
+		goto error_no_platform;
+
+	/* create a backlight device to talk to this one */
+	backlight_device = backlight_device_register("samsung", &sdev->dev,
+						     NULL, &backlight_ops);
+	if (IS_ERR(backlight_device))
+		goto error_no_backlight;
+
+	backlight_device->props.max_brightness = MAX_BRIGHT;
+	backlight_device->props.brightness = read_brightness();
+	backlight_device->props.power = FB_BLANK_UNBLANK;
+	backlight_update_status(backlight_device);
+
+	retval = init_wireless(sdev);
+	if (retval)
+		goto error_no_rfk;
+
+	retval = device_create_file(&sdev->dev, &dev_attr_silent);
+	if (retval)
+		goto error_file_create;
+
+exit:
+	return 0;
+
+error_file_create:
+	destroy_wireless();
+
+error_no_rfk:
+	backlight_device_unregister(backlight_device);
+
+error_no_backlight:
+	platform_device_unregister(sdev);
+
+error_no_platform:
+	iounmap(sabi_iface);
+
+error_no_signature:
+	iounmap(f0000_segment);
+	return -EINVAL;
+}
+
+static void __exit samsung_exit(void)
+{
+	/* Turn off "Linux" mode in the BIOS */
+	sabi_set_command(SET_LINUX, 0x80);
+
+	device_remove_file(&sdev->dev, &dev_attr_silent);
+	backlight_device_unregister(backlight_device);
+	destroy_wireless();
+	iounmap(sabi_iface);
+	iounmap(f0000_segment);
+	platform_device_unregister(sdev);
+}
+
+module_init(samsung_init);
+module_exit(samsung_exit);
+
+MODULE_AUTHOR("Greg Kroah-Hartman <gregkh@xxxxxxx>");
+MODULE_DESCRIPTION("Samsung Backlight driver");
+MODULE_LICENSE("GPL");