[PATCH] sony-laptop: limit brightness range to DSDT provided ones

The new style brightness control provides an operating range of 9 values
(seems consistent over a large number of models sharing the same
brightness control methods).
Read and use the minimum and maximum values to limit the backlight
interface between those boundaries.

Signed-off-by: Mattia Dongili <malattia@linux.it>
Signed-off-by: Matthew Garrett <mjg@redhat.com>

diff --git a/drivers/platform/x86/sony-laptop.c b/drivers/platform/x86/sony-laptop.c
index 9d80ae4..6fe8cd6 100644 (file)
--- a/drivers/platform/x86/sony-laptop.c
+++ b/drivers/platform/x86/sony-laptop.c
@@ -934,6 +934,14 @@ static ssize_t sony_nc_sysfs_store(struct device *dev,
 /*
  * Backlight device
  */
+struct sony_backlight_props {
+       struct backlight_device *dev;
+       int                     handle;
+       u8                      offset;
+       u8                      maxlvl;
+};
+struct sony_backlight_props sony_bl_props;
+
 static int sony_backlight_update_status(struct backlight_device *bd)
 {
        return acpi_callsetfunc(sony_nc_acpi_handle, "SBRT",
@@ -954,19 +962,23 @@ static int sony_nc_get_brightness_ng(struct backlight_device *bd)
 {
        int result;
        int *handle = (int *)bl_get_data(bd);
+       struct sony_backlight_props *sdev =
+               (struct sony_backlight_props *)bl_get_data(bd);
 
-       sony_call_snc_handle(*handle, 0x0200, &result);
+       sony_call_snc_handle(sdev->handle, 0x0200, &result);
 
-       return result & 0xff;
+       return (result & 0xff) - sdev->offset;
 }
 
 static int sony_nc_update_status_ng(struct backlight_device *bd)
 {
        int value, result;
        int *handle = (int *)bl_get_data(bd);
+       struct sony_backlight_props *sdev =
+               (struct sony_backlight_props *)bl_get_data(bd);
 
-       value = bd->props.brightness;
-       if (sony_call_snc_handle(*handle, 0x0100 | (value << 16), &result))
+       value = bd->props.brightness + sdev->offset;
+       if (sony_call_snc_handle(sdev->handle, 0x0100 | (value << 16), &result))
                return -EIO;
 
        return value;
@@ -982,8 +994,6 @@ static const struct backlight_ops sony_backlight_ng_ops = {
        .update_status = sony_nc_update_status_ng,
        .get_brightness = sony_nc_get_brightness_ng,
 };
-static int backlight_ng_handle;
-static struct backlight_device *sony_backlight_device;
 
 /*
  * New SNC-only Vaios event mapping to driver known keys
@@ -1550,6 +1560,75 @@ static void sony_nc_kbd_backlight_resume(void)
                                &ignore);
 }
 
+static void sony_nc_backlight_ng_read_limits(int handle,
+               struct sony_backlight_props *props)
+{
+       int offset;
+       acpi_status status;
+       u8 brlvl, i;
+       u8 min = 0xff, max = 0x00;
+       struct acpi_object_list params;
+       union acpi_object in_obj;
+       union acpi_object *lvl_enum;
+       struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+
+       props->handle = handle;
+       props->offset = 0;
+       props->maxlvl = 0xff;
+
+       offset = sony_find_snc_handle(handle);
+       if (offset < 0)
+               return;
+
+       /* try to read the boundaries from ACPI tables, if we fail the above
+        * defaults should be reasonable
+        */
+       params.count = 1;
+       params.pointer = &in_obj;
+       in_obj.type = ACPI_TYPE_INTEGER;
+       in_obj.integer.value = offset;
+       status = acpi_evaluate_object(sony_nc_acpi_handle, "SN06", &params,
+                       &buffer);
+       if (ACPI_FAILURE(status))
+               return;
+
+       lvl_enum = (union acpi_object *) buffer.pointer;
+       if (!lvl_enum) {
+               pr_err("No SN06 return object.");
+               return;
+       }
+       if (lvl_enum->type != ACPI_TYPE_BUFFER) {
+               pr_err("Invalid SN06 return object 0x%.2x\n",
+                      lvl_enum->type);
+               goto out_invalid;
+       }
+
+       /* the buffer lists brightness levels available, brightness levels are
+        * from 0 to 8 in the array, other values are used by ALS control.
+        */
+       for (i = 0; i < 9 && i < lvl_enum->buffer.length; i++) {
+
+               brlvl = *(lvl_enum->buffer.pointer + i);
+               dprintk("Brightness level: %d\n", brlvl);
+
+               if (!brlvl)
+                       break;
+
+               if (brlvl > max)
+                       max = brlvl;
+               if (brlvl < min)
+                       min = brlvl;
+       }
+       props->offset = min;
+       props->maxlvl = max;
+       dprintk("Brightness levels: min=%d max=%d\n", props->offset,
+                       props->maxlvl);
+
+out_invalid:
+       kfree(buffer.pointer);
+       return;
+}
+
 static void sony_nc_backlight_setup(void)
 {
        acpi_handle unused;
@@ -1558,14 +1637,14 @@ static void sony_nc_backlight_setup(void)
        struct backlight_properties props;
 
        if (sony_find_snc_handle(0x12f) != -1) {
-               backlight_ng_handle = 0x12f;
                ops = &sony_backlight_ng_ops;
-               max_brightness = 0xff;
+               sony_nc_backlight_ng_read_limits(0x12f, &sony_bl_props);
+               max_brightness = sony_bl_props.maxlvl - sony_bl_props.offset;
 
        } else if (sony_find_snc_handle(0x137) != -1) {
-               backlight_ng_handle = 0x137;
                ops = &sony_backlight_ng_ops;
-               max_brightness = 0xff;
+               sony_nc_backlight_ng_read_limits(0x137, &sony_bl_props);
+               max_brightness = sony_bl_props.maxlvl - sony_bl_props.offset;
 
        } else if (ACPI_SUCCESS(acpi_get_handle(sony_nc_acpi_handle, "GBRT",
                                                &unused))) {
@@ -1578,22 +1657,22 @@ static void sony_nc_backlight_setup(void)
        memset(&props, 0, sizeof(struct backlight_properties));
        props.type = BACKLIGHT_PLATFORM;
        props.max_brightness = max_brightness;
-       sony_backlight_device = backlight_device_register("sony", NULL,
-                                                         &backlight_ng_handle,
-                                                         ops, &props);
+       sony_bl_props.dev = backlight_device_register("sony", NULL,
+                                                     &sony_bl_props,
+                                                     ops, &props);
 
-       if (IS_ERR(sony_backlight_device)) {
-               pr_warning(DRV_PFX "unable to register backlight device\n");
-               sony_backlight_device = NULL;
+       if (IS_ERR(sony_bl_props.dev)) {
+               pr_warn(DRV_PFX "unable to register backlight device\n");
+               sony_bl_props.dev = NULL;
        } else
-               sony_backlight_device->props.brightness =
-                   ops->get_brightness(sony_backlight_device);
+               sony_bl_props.dev->props.brightness =
+                       ops->get_brightness(sony_bl_props.dev);
 }
 
 static void sony_nc_backlight_cleanup(void)
 {
-       if (sony_backlight_device)
-               backlight_device_unregister(sony_backlight_device);
+       if (sony_bl_props.dev)
+               backlight_device_unregister(sony_bl_props.dev);
 }
 
 static int sony_nc_add(struct acpi_device *device)
@@ -2591,7 +2670,7 @@ static long sonypi_misc_ioctl(struct file *fp, unsigned int cmd,
        mutex_lock(&spic_dev.lock);
        switch (cmd) {
        case SONYPI_IOCGBRT:
-               if (sony_backlight_device == NULL) {
+               if (sony_bl_props.dev == NULL) {
                        ret = -EIO;
                        break;
                }
@@ -2604,7 +2683,7 @@ static long sonypi_misc_ioctl(struct file *fp, unsigned int cmd,
                                ret = -EFAULT;
                break;
        case SONYPI_IOCSBRT:
-               if (sony_backlight_device == NULL) {
+               if (sony_bl_props.dev == NULL) {
                        ret = -EIO;
                        break;
                }
@@ -2618,8 +2697,8 @@ static long sonypi_misc_ioctl(struct file *fp, unsigned int cmd,
                        break;
                }
                /* sync the backlight device status */
-               sony_backlight_device->props.brightness =
-                   sony_backlight_get_brightness(sony_backlight_device);
+               sony_bl_props.dev->props.brightness =
+                   sony_backlight_get_brightness(sony_bl_props.dev);
                break;
        case SONYPI_IOCGBAT1CAP:
                if (ec_read16(SONYPI_BAT1_FULL, &val16)) {