ACPI: thinkpad-acpi: support 16 levels of brightness (v3)

Lenovo ThinkPads often have 16 brightness levels in EC, and not just eight
levels like older ThinkPads.  They also have standard ACPI backlight
brightness control.

We detect the number of brightness levels by the presence of a BCLL package
with 16 entries.  If BCLL is not there, we assume eight levels (Z6*).  If
it is there, but it doesn't have 16 entries, we assume eight levels (T60).
Otherwise we assume sixteen levels (T61, X61, etc).

We don't use _BCL because it can have side-effects in thinkpads.  Thanks to
Thomas Renninger <trenn@suse.de> for notifying me of this potential
problem.

Using the standard ACPI backlight brightness control *instead* of the
native thinkpad backlight control is a better idea, though.  A different
patch will take care of this.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Thomas Renninger <trenn@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>

2 files changed, 83 insertions, 11 deletions

diff --git a/drivers/misc/thinkpad_acpi.c b/drivers/misc/thinkpad_acpi.c
index 63b1e2610c60..322ba25b4798 100644
--- a/drivers/misc/thinkpad_acpi.c
+++ b/drivers/misc/thinkpad_acpi.c
@@ -3114,6 +3114,66 @@ static struct backlight_ops ibm_backlight_data = {
 
 static struct mutex brightness_mutex;
 
+static int __init tpacpi_query_bcll_levels(acpi_handle handle)
+{
+        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+        union acpi_object *obj;
+        int rc;
+
+        if (ACPI_SUCCESS(acpi_evaluate_object(handle, NULL, NULL, &buffer))) {
+                obj = (union acpi_object *)buffer.pointer;
+                if (!obj || (obj->type != ACPI_TYPE_PACKAGE)) {
+                        printk(IBM_ERR "Unknown BCLL data, "
+                               "please report this to %s\n", IBM_MAIL);
+                        rc = 0;
+                } else {
+                        rc = obj->package.count;
+                }
+        } else {
+                return 0;
+        }
+
+        kfree(buffer.pointer);
+        return rc;
+}
+
+static acpi_status __init brightness_find_bcll(acpi_handle handle, u32 lvl,
+                                        void *context, void **rv)
+{
+        char name[ACPI_PATH_SEGMENT_LENGTH];
+        struct acpi_buffer buffer = { sizeof(name), &name };
+
+        if (ACPI_SUCCESS(acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer)) &&
+            !strncmp("BCLL", name, sizeof(name) - 1)) {
+                if (tpacpi_query_bcll_levels(handle) == 16) {
+                        *rv = handle;
+                        return AE_CTRL_TERMINATE;
+                } else {
+                        return AE_OK;
+                }
+        } else {
+                return AE_OK;
+        }
+}
+
+static int __init brightness_check_levels(void)
+{
+        int status;
+        void *found_node = NULL;
+
+        if (!vid_handle) {
+                IBM_ACPIHANDLE_INIT(vid);
+        }
+        if (!vid_handle)
+                return 0;
+
+        /* Search for a BCLL package with 16 levels */
+        status = acpi_walk_namespace(ACPI_TYPE_PACKAGE, vid_handle, 3,
+                                        brightness_find_bcll, NULL, &found_node);
+
+        return (ACPI_SUCCESS(status) && found_node != NULL);
+}
+
 static int __init brightness_init(struct ibm_init_struct *iibm)
 {
         int b;
@@ -3135,10 +3195,17 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
         if (brightness_mode > 3)
                 return -EINVAL;
 
+        tp_features.bright_16levels =
+                        thinkpad_id.vendor == PCI_VENDOR_ID_LENOVO &&
+                        brightness_check_levels();
+
         b = brightness_get(NULL);
         if (b < 0)
                 return 1;
 
+        if (tp_features.bright_16levels)
+                printk(IBM_INFO "detected a 16-level brightness capable ThinkPad\n");
+
         ibm_backlight_device = backlight_device_register(
                                         TPACPI_BACKLIGHT_DEV_NAME, NULL, NULL,
                                         &ibm_backlight_data);
@@ -3148,7 +3215,8 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
         }
         vdbg_printk(TPACPI_DBG_INIT, "brightness is supported\n");
 
-        ibm_backlight_device->props.max_brightness = 7;
+        ibm_backlight_device->props.max_brightness =
+                                (tp_features.bright_16levels)? 15 : 7;
         ibm_backlight_device->props.brightness = b;
         backlight_update_status(ibm_backlight_device);
 
@@ -3184,13 +3252,14 @@ static int brightness_get(struct backlight_device *bd)
         if (brightness_mode & 1) {
                 if (!acpi_ec_read(brightness_offset, &lec))
                         return -EIO;
-                lec &= 7;
+                lec &= (tp_features.bright_16levels)? 0x0f : 0x07;
                 level = lec;
         };
         if (brightness_mode & 2) {
                 lcmos = (nvram_read_byte(TP_NVRAM_ADDR_BRIGHTNESS)
                          & TP_NVRAM_MASK_LEVEL_BRIGHTNESS)
                         >> TP_NVRAM_POS_LEVEL_BRIGHTNESS;
+                lcmos &= (tp_features.bright_16levels)? 0x0f : 0x07;
                 level = lcmos;
         }
 
@@ -3211,7 +3280,7 @@ static int brightness_set(int value)
         int cmos_cmd, inc, i, res;
         int current_value;
 
-        if (value > 7)
+        if (value > ((tp_features.bright_16levels)? 15 : 7))
                 return -EINVAL;
 
         res = mutex_lock_interruptible(&brightness_mutex);
@@ -3227,7 +3296,7 @@ static int brightness_set(int value)
         cmos_cmd = value > current_value ?
                         TP_CMOS_BRIGHTNESS_UP :
                         TP_CMOS_BRIGHTNESS_DOWN;
-        inc = value > current_value ? 1 : -1;
+        inc = (value > current_value)? 1 : -1;
 
         res = 0;
         for (i = current_value; i != value; i += inc) {
@@ -3256,10 +3325,11 @@ static int brightness_read(char *p)
         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);
+                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");
+                               " (<level> is 0-%d)\n",
+                               (tp_features.bright_16levels) ? 15 : 7);
         }
 
         return len;
@@ -3270,18 +3340,19 @@ static int brightness_write(char *buf)
         int level;
         int new_level;
         char *cmd;
+        int max_level = (tp_features.bright_16levels) ? 15 : 7;
 
         while ((cmd = next_cmd(&buf))) {
                 if ((level = brightness_get(NULL)) < 0)
                         return level;
-                level &= 7;
 
                 if (strlencmp(cmd, "up") == 0) {
-                        new_level = level == 7 ? 7 : level + 1;
+                        new_level = level == (max_level)?
+                                                max_level : level + 1;
                 } else if (strlencmp(cmd, "down") == 0) {
-                        new_level = level == 0 ? 0 : level - 1;
+                        new_level = level == 0? 0 : level - 1;
                 } else if (sscanf(cmd, "level %d", &new_level) == 1 &&
-                           new_level >= 0 && new_level <= 7) {
+                           new_level >= 0 && new_level <= max_level) {
                         /* new_level set */
                 } else
                         return -EINVAL;
diff --git a/drivers/misc/thinkpad_acpi.h b/drivers/misc/thinkpad_acpi.h
index 3abcc8120634..8ca19c333727 100644
--- a/drivers/misc/thinkpad_acpi.h
+++ b/drivers/misc/thinkpad_acpi.h
@@ -84,7 +84,7 @@
 
 /* ThinkPad CMOS NVRAM constants */
 #define TP_NVRAM_ADDR_BRIGHTNESS       0x5e
-#define TP_NVRAM_MASK_LEVEL_BRIGHTNESS 0x07
+#define TP_NVRAM_MASK_LEVEL_BRIGHTNESS 0x0f
 #define TP_NVRAM_POS_LEVEL_BRIGHTNESS 0
 
 #define onoff(status,bit) ((status) & (1 << (bit)) ? "on" : "off")
@@ -246,6 +246,7 @@ static struct {
         u32 hotkey_wlsw:1;
         u32 light:1;
         u32 light_status:1;
+        u32 bright_16levels:1;
         u32 wan:1;
         u32 fan_ctrl_status_undef:1;
         u32 input_device_registered:1;