thinkpad-acpi: let other subdrivers know backlight level range

Extract the backlight level range size detection from the brightness
subdriver, and allow the other subdrivers access to that information.

This also allows us to relocate some code to a more convenient place.
The moved code was largerly unmodified, except for the return type of
tpacpi_check_std_acpi_brightness_support(), which now is correctly
marked as returning "unsigned int", and and two cosmetic fixes to make
checkpatch.pl happy.

Fixes for the NVRAM polling mode for the brightness hotkeys will need
this.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>

drivers/platform/x86/thinkpad_acpi.c

@@ -304,8 +304,8 @@ static struct {
 	u32 hotkey_tablet:1;
 	u32 light:1;
 	u32 light_status:1;
-	u32 bright_16levels:1;
 	u32 bright_acpimode:1;
+	u32 bright_unkfw:1;
 	u32 wan:1;
 	u32 uwb:1;
 	u32 fan_ctrl_status_undef:1;
@@ -368,6 +368,9 @@ struct tpacpi_led_classdev {
 	unsigned int led;
 };
 
+/* brightness level capabilities */
+static unsigned int bright_maxlvl;	/* 0 = unknown */
+
 #ifdef CONFIG_THINKPAD_ACPI_DEBUGFACILITIES
 static int dbg_wlswemul;
 static int tpacpi_wlsw_emulstate;
@@ -1051,80 +1054,6 @@ static void tpacpi_disable_brightness_delay(void)
 			"ACPI backlight control delay disabled\n");
 }
 
-static int __init tpacpi_query_bcl_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(TPACPI_ERR "Unknown _BCL data, "
-			       "please report this to %s\n", TPACPI_MAIL);
-			rc = 0;
-		} else {
-			rc = obj->package.count;
-		}
-	} else {
-		return 0;
-	}
-
-	kfree(buffer.pointer);
-	return rc;
-}
-
-static acpi_status __init tpacpi_acpi_walk_find_bcl(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("_BCL", name, sizeof(name) - 1)) {
-		BUG_ON(!rv || !*rv);
-		**(int **)rv = tpacpi_query_bcl_levels(handle);
-		return AE_CTRL_TERMINATE;
-	} else {
-		return AE_OK;
-	}
-}
-
-/*
- * Returns 0 (no ACPI _BCL or _BCL invalid), or size of brightness map
- */
-static int __init tpacpi_check_std_acpi_brightness_support(void)
-{
-	int status;
-	int bcl_levels = 0;
-	void *bcl_ptr = &bcl_levels;
-
-	if (!vid_handle) {
-		TPACPI_ACPIHANDLE_INIT(vid);
-	}
-	if (!vid_handle)
-		return 0;
-
-	/*
-	 * Search for a _BCL method, and execute it.  This is safe on all
-	 * ThinkPads, and as a side-effect, _BCL will place a Lenovo Vista
-	 * BIOS in ACPI backlight control mode.  We do NOT have to care
-	 * about calling the _BCL method in an enabled video device, any
-	 * will do for our purposes.
-	 */
-
-	status = acpi_walk_namespace(ACPI_TYPE_METHOD, vid_handle, 3,
-				     tpacpi_acpi_walk_find_bcl, NULL, NULL,
-				     &bcl_ptr);
-
-	if (ACPI_SUCCESS(status) && bcl_levels > 2) {
-		tp_features.bright_acpimode = 1;
-		return (bcl_levels - 2);
-	}
-
-	return 0;
-}
-
 static void printk_deprecated_attribute(const char * const what,
 					const char * const details)
 {
@@ -3420,11 +3349,8 @@ static int __init hotkey_init(struct ibm_init_struct *iibm)
 	}
 
 	/* Do not issue duplicate brightness change events to
-	 * userspace */
-	if (!tp_features.bright_acpimode)
-		/* update bright_acpimode... */
-		tpacpi_check_std_acpi_brightness_support();
-
+	 * userspace. tpacpi_detect_brightness_capabilities() must have
+	 * been called before this point  */
 	if (tp_features.bright_acpimode && acpi_video_backlight_support()) {
 		printk(TPACPI_INFO
 		       "This ThinkPad has standard ACPI backlight "
@@ -5989,7 +5915,7 @@ static unsigned int tpacpi_brightness_nvram_get(void)
 	lnvram = (nvram_read_byte(TP_NVRAM_ADDR_BRIGHTNESS)
 		  & TP_NVRAM_MASK_LEVEL_BRIGHTNESS)
 		  >> TP_NVRAM_POS_LEVEL_BRIGHTNESS;
-	lnvram &= (tp_features.bright_16levels) ? 0x0f : 0x07;
+	lnvram &= bright_maxlvl;
 
 	return lnvram;
 }
@@ -6098,8 +6024,7 @@ static int brightness_set(unsigned int value)
 {
 	int res;
 
-	if (value > ((tp_features.bright_16levels)? 15 : 7) ||
-	    value < 0)
+	if (value > bright_maxlvl || value < 0)
 		return -EINVAL;
 
 	vdbg_printk(TPACPI_DBG_BRGHT,
@@ -6174,6 +6099,80 @@ static struct backlight_ops ibm_backlight_data = {
 
 /* --------------------------------------------------------------------- */
 
+static int __init tpacpi_query_bcl_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(TPACPI_ERR "Unknown _BCL data, "
+			       "please report this to %s\n", TPACPI_MAIL);
+			rc = 0;
+		} else {
+			rc = obj->package.count;
+		}
+	} else {
+		return 0;
+	}
+
+	kfree(buffer.pointer);
+	return rc;
+}
+
+static acpi_status __init tpacpi_acpi_walk_find_bcl(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("_BCL", name, sizeof(name) - 1)) {
+		BUG_ON(!rv || !*rv);
+		**(int **)rv = tpacpi_query_bcl_levels(handle);
+		return AE_CTRL_TERMINATE;
+	} else {
+		return AE_OK;
+	}
+}
+
+/*
+ * Returns 0 (no ACPI _BCL or _BCL invalid), or size of brightness map
+ */
+static unsigned int __init tpacpi_check_std_acpi_brightness_support(void)
+{
+	int status;
+	int bcl_levels = 0;
+	void *bcl_ptr = &bcl_levels;
+
+	if (!vid_handle)
+		TPACPI_ACPIHANDLE_INIT(vid);
+
+	if (!vid_handle)
+		return 0;
+
+	/*
+	 * Search for a _BCL method, and execute it.  This is safe on all
+	 * ThinkPads, and as a side-effect, _BCL will place a Lenovo Vista
+	 * BIOS in ACPI backlight control mode.  We do NOT have to care
+	 * about calling the _BCL method in an enabled video device, any
+	 * will do for our purposes.
+	 */
+
+	status = acpi_walk_namespace(ACPI_TYPE_METHOD, vid_handle, 3,
+				     tpacpi_acpi_walk_find_bcl, NULL, NULL,
+				     &bcl_ptr);
+
+	if (ACPI_SUCCESS(status) && bcl_levels > 2) {
+		tp_features.bright_acpimode = 1;
+		return bcl_levels - 2;
+	}
+
+	return 0;
+}
+
 /*
  * These are only useful for models that have only one possibility
  * of GPU.  If the BIOS model handles both ATI and Intel, don't use
@@ -6204,6 +6203,47 @@ static const struct tpacpi_quirk brightness_quirk_table[] __initconst = {
 	TPACPI_Q_IBM('7', '5', TPACPI_BRGHT_Q_NOEC),	/* X41 Tablet */
 };
 
+/*
+ * Returns < 0 for error, otherwise sets tp_features.bright_*
+ * and bright_maxlvl.
+ */
+static void __init tpacpi_detect_brightness_capabilities(void)
+{
+	unsigned int b;
+
+	vdbg_printk(TPACPI_DBG_INIT,
+		    "detecting firmware brightness interface capabilities\n");
+
+	/* we could run a quirks check here (same table used by
+	 * brightness_init) if needed */
+
+	/*
+	 * We always attempt to detect acpi support, so as to switch
+	 * Lenovo Vista BIOS to ACPI brightness mode even if we are not
+	 * going to publish a backlight interface
+	 */
+	b = tpacpi_check_std_acpi_brightness_support();
+	switch (b) {
+	case 16:
+		bright_maxlvl = 15;
+		printk(TPACPI_INFO
+		       "detected a 16-level brightness capable ThinkPad\n");
+		break;
+	case 8:
+	case 0:
+		bright_maxlvl = 7;
+		printk(TPACPI_INFO
+		       "detected a 8-level brightness capable ThinkPad\n");
+		break;
+	default:
+		printk(TPACPI_ERR
+		       "Unsupported brightness interface, "
+		       "please contact %s\n", TPACPI_MAIL);
+		tp_features.bright_unkfw = 1;
+		bright_maxlvl = b - 1;
+	}
+}
+
 static int __init brightness_init(struct ibm_init_struct *iibm)
 {
 	struct backlight_properties props;
@@ -6217,14 +6257,13 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
 	quirks = tpacpi_check_quirks(brightness_quirk_table,
 				ARRAY_SIZE(brightness_quirk_table));
 
-	/*
-	 * We always attempt to detect acpi support, so as to switch
-	 * Lenovo Vista BIOS to ACPI brightness mode even if we are not
-	 * going to publish a backlight interface
-	 */
-	b = tpacpi_check_std_acpi_brightness_support();
-	if (b > 0) {
+	/* tpacpi_detect_brightness_capabilities() must have run already */
+
+	/* if it is unknown, we don't handle it: it wouldn't be safe */
+	if (tp_features.bright_unkfw)
+		return 1;
 
+	if (tp_features.bright_acpimode) {
 		if (acpi_video_backlight_support()) {
 			if (brightness_enable > 1) {
 				printk(TPACPI_NOTICE
@@ -6253,15 +6292,6 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
 		return 1;
 	}
 
-	if (b > 16) {
-		printk(TPACPI_ERR
-		       "Unsupported brightness interface, "
-		       "please contact %s\n", TPACPI_MAIL);
-		return 1;
-	}
-	if (b == 16)
-		tp_features.bright_16levels = 1;
-
 	/*
 	 * Check for module parameter bogosity, note that we
 	 * init brightness_mode to TPACPI_BRGHT_MODE_MAX in order to be
@@ -6292,12 +6322,9 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
 	if (tpacpi_brightness_get_raw(&b) < 0)
 		return 1;
 
-	if (tp_features.bright_16levels)
-		printk(TPACPI_INFO
-		       "detected a 16-level brightness capable ThinkPad\n");
-
 	memset(&props, 0, sizeof(struct backlight_properties));
-	props.max_brightness = (tp_features.bright_16levels) ? 15 : 7;
+	props.max_brightness = bright_maxlvl;
+	props.brightness = b & TP_EC_BACKLIGHT_LVLMSK;
 	ibm_backlight_device = backlight_device_register(TPACPI_BACKLIGHT_DEV_NAME,
 							 NULL, NULL,
 							 &ibm_backlight_data,
@@ -6320,7 +6347,6 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
 			"or not on your ThinkPad\n", TPACPI_MAIL);
 	}
 
-	ibm_backlight_device->props.brightness = b & TP_EC_BACKLIGHT_LVLMSK;
 	backlight_update_status(ibm_backlight_device);
 
 	vdbg_printk(TPACPI_DBG_INIT | TPACPI_DBG_BRGHT,
@@ -6363,9 +6389,8 @@ static int brightness_read(struct seq_file *m)
 	} else {
 		seq_printf(m, "level:\t\t%d\n", level);
 		seq_printf(m, "commands:\tup, down\n");
-		seq_printf(m, "commands:\tlevel <level>"
-			       " (<level> is 0-%d)\n",
-			       (tp_features.bright_16levels) ? 15 : 7);
+		seq_printf(m, "commands:\tlevel <level> (<level> is 0-%d)\n",
+			       bright_maxlvl);
 	}
 
 	return 0;
@@ -6376,7 +6401,6 @@ static int brightness_write(char *buf)
 	int level;
 	int rc;
 	char *cmd;
-	int max_level = (tp_features.bright_16levels) ? 15 : 7;
 
 	level = brightness_get(NULL);
 	if (level < 0)
@@ -6384,13 +6408,13 @@ static int brightness_write(char *buf)
 
 	while ((cmd = next_cmd(&buf))) {
 		if (strlencmp(cmd, "up") == 0) {
-			if (level < max_level)
+			if (level < bright_maxlvl)
 				level++;
 		} else if (strlencmp(cmd, "down") == 0) {
 			if (level > 0)
 				level--;
 		} else if (sscanf(cmd, "level %d", &level) == 1 &&
-			   level >= 0 && level <= max_level) {
+			   level >= 0 && level <= bright_maxlvl) {
 			/* new level set */
 		} else
 			return -EINVAL;
@@ -9130,6 +9154,11 @@ static int __init thinkpad_acpi_module_init(void)
 		tpacpi_inputdev->id.version = TPACPI_HKEY_INPUT_VERSION;
 		tpacpi_inputdev->dev.parent = &tpacpi_pdev->dev;
 	}
+
+	/* Init subdriver dependencies */
+	tpacpi_detect_brightness_capabilities();
+
+	/* Init subdrivers */
 	for (i = 0; i < ARRAY_SIZE(ibms_init); i++) {
 		ret = ibm_init(&ibms_init[i]);
 		if (ret >= 0 && *ibms_init[i].param)