[PATCH v3] video: leds: backlight: lm3533: Support getting LED sources from DT

[Svyatoslav Ryhel <clamor95@gmail.com>]

Add Control Bank to HVLED/LVLED muxing support based on the led-sources
defined in the device tree.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>
---
This was part of the original LM3533 controller DT/OF conversion patchset,
but it appears to have been accidentally separated during the final iteration.
Therefore, I am sending it as a follow-up.

Changes in v2:
- leds: switch to macros in regmap_update_bits() calls to apply 0xff mask
  since regmap writes may cause unwanted writing.

Changes in v3:
- leds part moved into a separate patchset
- switched to dev_err_probe()
- for loop moved out of if condition
---
 drivers/video/backlight/lm3533_bl.c | 44 +++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/drivers/video/backlight/lm3533_bl.c b/drivers/video/backlight/lm3533_bl.c
index fd6e7f4f1f61c..cb9df6ff73001 100644
--- a/drivers/video/backlight/lm3533_bl.c
+++ b/drivers/video/backlight/lm3533_bl.c
@@ -7,6 +7,7 @@
  * Author: Johan Hovold <jhovold@gmail.com>
  */
 
+#include <linux/bits.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/platform_device.h>
@@ -21,6 +22,7 @@
 #define LM3533_HVCTRLBANK_COUNT		2
 #define LM3533_BL_MAX_BRIGHTNESS	255
 
+#define LM3533_REG_OUTPUT_CONF1		0x10
 #define LM3533_REG_CTRLBANK_AB_BCONF	0x1a
 #define   CTRLBANK_AB_BCONF_ALS(n)	BIT(2 * (n))
 #define   CTRLBANK_AB_BCONF_MODE(n)	BIT(2 * (n) + 1)
@@ -35,6 +37,9 @@ struct lm3533_bl {
 	u32 max_current;
 	u32 pwm;
 
+	int num_leds;
+	u32 led_strings[LM3533_HVCTRLBANK_COUNT];
+
 	bool have_als;
 	bool linear;
 };
@@ -236,6 +241,8 @@ static const struct attribute_group *lm3533_bl_attribute_groups[] = {
 static int lm3533_bl_setup(struct lm3533_bl *bl)
 {
 	int ctrlbank = lm3533_bl_get_ctrlbank_id(bl);
+	u32 output_cfg_val = 0;
+	u32 output_cfg_mask = 0;
 	int ret;
 
 	ret = regmap_assign_bits(bl->regmap, LM3533_REG_CTRLBANK_AB_BCONF,
@@ -243,6 +250,21 @@ static int lm3533_bl_setup(struct lm3533_bl *bl)
 	if (ret)
 		return ret;
 
+	for (int i = 0; i < bl->num_leds; i++) {
+		if (bl->led_strings[i] >= LM3533_HVCTRLBANK_COUNT)
+			continue;
+
+		output_cfg_val |= ctrlbank << bl->led_strings[i];
+		output_cfg_mask |= BIT(bl->led_strings[i]);
+	}
+
+	if (bl->num_leds) {
+		ret = regmap_update_bits(bl->regmap, LM3533_REG_OUTPUT_CONF1,
+					 output_cfg_mask, output_cfg_val);
+		if (ret)
+			return ret;
+	}
+
 	ret = lm3533_ctrlbank_set_max_current(&bl->cb, bl->max_current);
 	if (ret)
 		return ret;
@@ -320,6 +342,28 @@ static int lm3533_bl_probe(struct platform_device *pdev)
 
 	device_property_read_u32(&pdev->dev, "ti,pwm-config-mask", &bl->pwm);
 
+	/*
+	 * If led-sources property is not set then either this Control Bank uses
+	 * its default HVLED or is not linked to any HVLED at all.
+	 */
+	bl->num_leds = device_property_count_u32(&pdev->dev, "led-sources");
+	if (bl->num_leds > LM3533_HVCTRLBANK_COUNT)
+		return dev_err_probe(&pdev->dev, -EINVAL,
+				     "num of LED sources %d exceeds max %d\n",
+				     bl->num_leds, LM3533_HVCTRLBANK_COUNT);
+
+	if (bl->num_leds < 0)
+		bl->num_leds = 0;
+
+	if (bl->num_leds > 0) {
+		ret = device_property_read_u32_array(&pdev->dev, "led-sources",
+						     bl->led_strings,
+						     bl->num_leds);
+		if (ret)
+			return dev_err_probe(&pdev->dev, ret,
+					     "failed to get led-sources\n");
+	}
+
 	ret = lm3533_bl_setup(bl);
 	if (ret)
 		return ret;
-- 
2.53.0