PATCH [2/3]: Provide generic backlight support in IBM ACPI driver

Matthew Garrett
2006-04-18T08:31:01Z

This provides support for altering IBM backlight brightness via
/sys/class/backlight. It does not remove the legacy /proc interface.

Signed-off-by: Matthew Garrett <mjg59@srcf.ucam.org>

diff -urp drivers/acpi.bak/ibm_acpi.c drivers/acpi/ibm_acpi.c
--- drivers/acpi.bak/ibm_acpi.c 2006-04-03 04:22:10 +0100
+++ a/drivers/acpi/ibm_acpi.c 2006-04-18 09:19:21 +0100
@@ -78,6 +78,8 @@
#include <linux/init.h>
#include <linux/types.h>
#include <linux/proc_fs.h>
+#include <linux/backlight.h>
+#include <linux/err.h>
#include <asm/uaccess.h>

#include <acpi/acpi_drivers.h>
@@ -243,6 +245,8 @@ 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)))
@@ -1318,15 +1322,25 @@ static int ecdump_write(char *buf)

static int brightness_offset = 0x31;

+static int brightness_read_value(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 = brightness_read_value(NULL);

- if (!acpi_ec_read(brightness_offset, &level)) {
+ if (level < 0) {
len += sprintf(p + len, "level:\t\tunreadable\n");
} else {
- len += sprintf(p + len, "level:\t\t%d\n", level & 0x7);
+ len += sprintf(p + len, "level:\t\t%d\n", level);
len += sprintf(p + len, "commands:\tup, down\n");
len += sprintf(p + len, "commands:\tlevel <level>"
" (<level> is 0-7)\n");
@@ -1338,9 +1352,38 @@ static int brightness_read(char *p)
#define BRIGHTNESS_UP 4
#define BRIGHTNESS_DOWN 5

+static int brightness_write_value(struct backlight_device *bd, int value)
+{
+ int current_value = brightness_read_value(bd);
+ int inc;
+ int cmos_cmd;
+
+ value &= 7;
+
+ cmos_cmd = value > current_value ? BRIGHTNESS_UP : BRIGHTNESS_DOWN;
+
+ inc = value > current_value ? 1 : -1;
+
+ while (value != current_value) {
+ current_value += inc;
+
+ if (!cmos_eval(cmos_cmd))
+ return -EIO;
+ if (!acpi_ec_write(brightness_offset, current_value))
+ return -EIO;
+ }
+
+ return 0;
+}
+
+static int brightness_update_value(struct backlight_device *bd)
+{
+ int value = bd->props->brightness;
+ return brightness_write_value(bd, value);
+}
+
static int brightness_write(char *buf)
{
- int cmos_cmd, inc, i;
u8 level;
int new_level;
char *cmd;
@@ -1360,14 +1403,8 @@ 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_write_value(NULL, new_level);
+
}

return 0;
@@ -1895,10 +1932,20 @@ IBM_PARAM(brightness);
IBM_PARAM(volume);
IBM_PARAM(fan);

+
+static struct backlight_properties ibmbl_data = {
+ .owner = THIS_MODULE,
+ .get_brightness = brightness_read_value,
+ .update_status = brightness_update_value,
+ .max_brightness = 7,
+};
+
static void acpi_ibm_exit(void)
{
int i;

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

@@ -1966,6 +2013,11 @@ static int __init acpi_ibm_init(void)
}
}

+ ibm_backlight_device = backlight_device_register ("ibm_bl", NULL,
+ &ibmbl_data);
+ if (IS_ERR (ibm_backlight_device))
+ acpi_ibm_exit();
+
return 0;
}

diff -urp drivers/acpi.bak/Kconfig drivers/acpi/Kconfig
--- drivers/acpi.bak/Kconfig 2006-04-18 08:51:49 +0100
+++ a/drivers/acpi/Kconfig 2006-04-18 09:13:09 +0100
@@ -195,7 +195,7 @@ config ACPI_ASUS

config ACPI_IBM
tristate "IBM ThinkPad Laptop Extras"
- depends on X86
+ depends on X86 && BACKLIGHT_DEVICE
---help---
This is a Linux ACPI driver for the IBM ThinkPad laptops. It adds
support for Fn-Fx key combinations, Bluetooth control, video