[RFC] [PATCH] panasonic-laptop.c: add support for CD power management

[Martin Lucina <mato@kotelna.sk>]

Hello,

attached is a patch to the panasonic-laptop driver to enable power
management (i.e. on/off) of the built-in optical drive.  It creates a
sysfs interface /sys/devices/platform/panasonic/cdpower which can be
either queried or written to.  Writing "0" enables the device, "1"
disables it.

This code is based on reading the existing code[1][2],
examining the DSDT on my CF-W4 system and experimentation.

The presence of the CF-Y series in the DMI table is based on the
assumption that this method works on recent CF-Yx models.

I have a few questions I'd like to clear up before actually submitting
this for inclusion:

1) Is a platform device the right way to do this?

2) Rather than checking the DMI system vendor and product name would it
be a better approach to simply check for the presence of the \_SB.FBAY()
and \_SB.STAT() ACPI methods and enable the platform device on any
(Panasonic) system where these are present?  This would seem like a
more future-proof approach.

3) Please advise on the correct way to propagate an error result from
the functions that call the ACPI methods {get,set}optd_power_state() to
userspace in the sysfs interface.  I couldn't find a straightforward
example anywhere.

Thanks!

-mato

[1] Referenced here http://www.da-cha.jp/letsnote as "A patch to handle
CD on/off button(need to merge)" (now a dead link)
[2] http://www.netlab.is.tsukuba.ac.jp/~yokota/izumi/panasonic_acpi/,
see the 20070907 version ("includes small hack for CD-ROM drive")

---

--- linux-2.6.28/drivers/misc/panasonic-laptop.c.orig	2009-01-13 17:01:53.327106958 +0100
+++ linux-2.6.28/drivers/misc/panasonic-laptop.c	2009-01-13 17:04:04.911106197 +0100
@@ -24,6 +24,8 @@
  *---------------------------------------------------------------------------
  *
  * ChangeLog:
+ *	Jan.13, 2009    Martin Lucina <mato@kotelna.sk>
+ *		-v0.96  add support for optical drive power in Y and W series
  *	Sep.23, 2008	Harald Welte <laforge@gnumonks.org>
  *		-v0.95	rename driver from drivers/acpi/pcc_acpi.c to
  *			drivers/misc/panasonic-laptop.c
@@ -127,6 +129,8 @@
 #include <acpi/acpi_bus.h>
 #include <acpi/acpi_drivers.h>
 #include <linux/input.h>
+#include <linux/platform_device.h>
+#include <linux/dmi.h>
 
 
 #ifndef ACPI_HOTKEY_COMPONENT
@@ -219,6 +223,7 @@ struct pcc_acpi {
 	struct acpi_device	*device;
 	struct input_dev	*input_dev;
 	struct backlight_device	*backlight;
+	struct platform_device  *platform;
 	int			keymap[KEYMAP_SIZE];
 };
 
@@ -226,6 +231,27 @@ struct pcc_keyinput {
 	struct acpi_hotkey      *hotkey;
 };
 
+/* known models with optical drive */
+static struct dmi_system_id pcc_platform_dmi_table[] = {
+	{
+		.ident = "Panasonic Toughbook W Series",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, 
+				"Matsushita Electric Industrial Co.,Ltd."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "CF-W"),
+		},
+	},
+	{
+		 .ident = "Panasonic Toughbook Y Series",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR,
+				"Matsushita Electric Industrial Co.,Ltd."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "CF-Y"),
+		},
+	},
+	{ }
+};
+
 /* method access functions */
 static int acpi_pcc_write_sset(struct pcc_acpi *pcc, int func, int val)
 {
@@ -360,6 +386,63 @@ static struct backlight_ops pcc_backligh
 	.update_status	= bl_set_status,
 };
 
+/* get optical driver power state */
+
+static int get_optd_power_state(void)
+{
+	acpi_status status;
+	unsigned long long state;
+	int result;
+	
+	status = acpi_evaluate_integer(NULL, "\\_SB.STAT", NULL, &state);
+	if (ACPI_FAILURE(status)) {
+		result = -EIO;
+		goto out;
+	}
+	switch (state) {
+	case 0: /* power off */
+		result = 1;
+		break;
+	case 0x0f: /* power on */
+		result = 0;
+		break;
+	default:
+		result = -EIO;
+		break;
+	}
+out:
+	return result;
+}
+
+/* set optical drive power state */
+
+static int set_optd_power_state(int new_state)
+{
+	int state, result;
+	acpi_status status;
+
+	state = get_optd_power_state();
+	if (new_state == state)
+		return 0;
+
+	result = 0;
+	switch (new_state) {
+	case 0: /* power on */
+		status = acpi_evaluate_object (NULL, "\\_SB.FBAY", NULL, NULL);
+		if (ACPI_FAILURE(status))
+			result = -EIO;
+		break;
+	case 1: /* power off */
+		status = acpi_evaluate_object (NULL, "\\_SB.CDDI", NULL, NULL);
+		if (ACPI_FAILURE(status))
+			result = -EIO;
+		break;
+	default:
+		result = -EINVAL;
+		break;
+	}
+	return result;
+}
 
 /* sysfs user interface functions */
 
@@ -427,10 +510,29 @@ static ssize_t set_sticky(struct device 
 	return count;
 }
 
+static ssize_t show_cdpower(struct device *dev, struct device_attribute *attr,
+			    char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "%d\n", get_optd_power_state());
+}
+
+static ssize_t set_cdpower(struct device *dev, struct device_attribute *attr,
+			   const char *buf, size_t count)
+{
+	int value;
+
+	if (count) {
+		value = simple_strtoul(buf, NULL, 10);
+		set_optd_power_state (value);
+	}
+	return count;
+}
+
 static DEVICE_ATTR(numbatt, S_IRUGO, show_numbatt, NULL);
 static DEVICE_ATTR(lcdtype, S_IRUGO, show_lcdtype, NULL);
 static DEVICE_ATTR(mute, S_IRUGO, show_mute, NULL);
 static DEVICE_ATTR(sticky_key, S_IRUGO | S_IWUSR, show_sticky, set_sticky);
+static DEVICE_ATTR(cdpower, S_IRUGO | S_IWUSR, show_cdpower, set_cdpower);
 
 static struct attribute *pcc_sysfs_entries[] = {
 	&dev_attr_numbatt.attr,
@@ -691,8 +793,26 @@ static int acpi_pcc_hotkey_add(struct ac
 	if (result)
 		goto out_backlight;
 
+	/* platform device initialization */
+	if (!dmi_check_system(pcc_platform_dmi_table)) {
+		pcc->platform = NULL;
+		goto out_no_optd;
+	}
+	pcc->platform = platform_device_register_simple("panasonic", -1,
+		NULL, 0);
+	if (IS_ERR(pcc->platform)) {
+		result = PTR_ERR(pcc->platform);
+		goto out_backlight;
+	}
+	result = device_create_file(&pcc->platform->dev, &dev_attr_cdpower);
+	if (result)
+		goto out_platform;
+
+out_no_optd:
 	return 0;
 
+out_platform:
+	platform_device_unregister(pcc->platform);
 out_backlight:
 	backlight_device_unregister(pcc->backlight);
 out_notify:
@@ -738,6 +858,11 @@ static int acpi_pcc_hotkey_remove(struct
 	if (!device || !pcc)
 		return -EINVAL;
 
+	if (pcc->platform) {
+		device_remove_file(&pcc->platform->dev, &dev_attr_cdpower);
+		platform_device_unregister(pcc->platform);
+	}
+
 	sysfs_remove_group(&device->dev.kobj, &pcc_attr_group);
 
 	backlight_device_unregister(pcc->backlight);