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Subject[PATCH] Add support for the generic backlight device to the IBM ACPI driver
Add support for the generic backlight interface below
/sys/class/backlight. The patch keeps the procfs brightness handling for
backward compatibility. For this to archive, the patch adds two generic
functions brightness_get and brightness_set to be used both by the procfs
related and the sysfs related methods.

Signed-off-by: Holger Macht <hmacht@suse.de>
---
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 0f9d4be..6e47501 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -200,6 +200,7 @@ config ACPI_ASUS
config ACPI_IBM
tristate "IBM ThinkPad Laptop Extras"
depends on X86
+ select BACKLIGHT
---help---
This is a Linux ACPI driver for the IBM ThinkPad laptops. It adds
support for Fn-Fx key combinations, Bluetooth control, video
diff --git a/drivers/acpi/ibm_acpi.c b/drivers/acpi/ibm_acpi.c
index 15fc124..1160f92 100644
--- a/drivers/acpi/ibm_acpi.c
+++ b/drivers/acpi/ibm_acpi.c
@@ -78,6 +78,7 @@ #include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/proc_fs.h>
+#include <linux/backlight.h>
#include <asm/uaccess.h>

#include <acpi/acpi_drivers.h>
@@ -243,6 +244,8 @@ struct ibm_struct {

static struct proc_dir_entry *proc_dir = NULL;

+static struct backlight_device *ibm_backlight_device;
+
#define onoff(status,bit) ((status) & (1 << (bit)) ? "on" : "off")
#define enabled(status,bit) ((status) & (1 << (bit)) ? "enabled" : "disabled")
#define strlencmp(a,b) (strncmp((a), (b), strlen(b)))
@@ -1381,12 +1384,22 @@ static int ecdump_write(char *buf)

static int brightness_offset = 0x31;

+static int brightness_get(struct backlight_device *bd)
+{
+ u8 level;
+ if (!acpi_ec_read(brightness_offset, &level))
+ return -EIO;
+
+ level &= 0x7;
+ return level;
+}
+
static int brightness_read(char *p)
{
int len = 0;
- u8 level;
+ int level;

- if (!acpi_ec_read(brightness_offset, &level)) {
+ if ((level = brightness_get(NULL)) < 0) {
len += sprintf(p + len, "level:\t\tunreadable\n");
} else {
len += sprintf(p + len, "level:\t\t%d\n", level & 0x7);
@@ -1401,16 +1414,34 @@ static int brightness_read(char *p)
#define BRIGHTNESS_UP 4
#define BRIGHTNESS_DOWN 5

-static int brightness_write(char *buf)
+static int brightness_set(int value)
{
int cmos_cmd, inc, i;
- u8 level;
+ int current_value = brightness_get(NULL);
+
+ value &= 7;
+
+ cmos_cmd = value > current_value ? BRIGHTNESS_UP : BRIGHTNESS_DOWN;
+ inc = value > current_value ? 1 : -1;
+ for (i = current_value; i != value; i += inc) {
+ if (!cmos_eval(cmos_cmd))
+ return -EIO;
+ if (!acpi_ec_write(brightness_offset, i + inc))
+ return -EIO;
+ }
+
+ return 0;
+}
+
+static int brightness_write(char *buf)
+{
+ int level;
int new_level;
char *cmd;

while ((cmd = next_cmd(&buf))) {
- if (!acpi_ec_read(brightness_offset, &level))
- return -EIO;
+ if ((level = brightness_get(NULL)) < 0)
+ return level;
level &= 7;

if (strlencmp(cmd, "up") == 0) {
@@ -1423,19 +1454,17 @@ static int brightness_write(char *buf)
} else
return -EINVAL;

- cmos_cmd = new_level > level ? BRIGHTNESS_UP : BRIGHTNESS_DOWN;
- inc = new_level > level ? 1 : -1;
- for (i = level; i != new_level; i += inc) {
- if (!cmos_eval(cmos_cmd))
- return -EIO;
- if (!acpi_ec_write(brightness_offset, i + inc))
- return -EIO;
- }
+ brightness_set(new_level);
}

return 0;
}

+static int brightness_update_status(struct backlight_device *bd)
+{
+ return brightness_set(bd->props->brightness);
+}
+
static int volume_offset = 0x30;

static int volume_read(char *p)
@@ -1965,10 +1994,20 @@ IBM_PARAM(brightness);
IBM_PARAM(volume);
IBM_PARAM(fan);

+static struct backlight_properties ibm_backlight_data = {
+ .owner = THIS_MODULE,
+ .get_brightness = brightness_get,
+ .update_status = brightness_update_status,
+ .max_brightness = 7,
+};
+
static void acpi_ibm_exit(void)
{
int i;

+ if (ibm_backlight_device)
+ backlight_device_unregister(ibm_backlight_device);
+
for (i = ARRAY_SIZE(ibms) - 1; i >= 0; i--)
ibm_exit(&ibms[i]);

@@ -2036,6 +2075,14 @@ #endif
}
}

+ ibm_backlight_device = backlight_device_register("ibm", NULL,
+ &ibm_backlight_data);
+ if (IS_ERR(ibm_backlight_device)) {
+ printk(IBM_ERR "Could not register ibm backlight device\n");
+ ibm_backlight_device = NULL;
+ acpi_ibm_exit();
+ }
+
return 0;
}
-
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