leds: leds-is31fl32xx: Add support for is31fl3236a

Also add an additional and optional control register for setting the
output PWM frequency to 22kHz. The default is 3kHz and this option puts
the operational frequency outside of the audible range.

Signed-off-by: Pawel Zalewski <pzalewski@thegoodpenguin.co.uk>
Link: https://lore.kernel.org/r/20250723-leds-is31fl3236a-v6-3-210328058625@thegoodpenguin.co.uk
Signed-off-by: Lee Jones <lee@kernel.org>

Author: pzalewski-thegoodpenguin

drivers/leds/leds-is31fl32xx.c

@@ -32,6 +32,8 @@
 #define IS31FL3216_CONFIG_SSD_ENABLE  BIT(7)
 #define IS31FL3216_CONFIG_SSD_DISABLE 0
 
+#define IS31FL32XX_PWM_FREQUENCY_22KHZ  0x01
+
 struct is31fl32xx_priv;
 struct is31fl32xx_led_data {
 	struct led_classdev cdev;
@@ -53,6 +55,7 @@ struct is31fl32xx_priv {
  * @pwm_update_reg      : address of PWM Update register
  * @global_control_reg  : address of Global Control register (optional)
  * @reset_reg           : address of Reset register (optional)
+ * @output_frequency_setting_reg: address of output frequency register (optional)
  * @pwm_register_base   : address of first PWM register
  * @pwm_registers_reversed: : true if PWM registers count down instead of up
  * @led_control_register_base : address of first LED control register (optional)
@@ -76,6 +79,7 @@ struct is31fl32xx_chipdef {
 	u8	pwm_update_reg;
 	u8	global_control_reg;
 	u8	reset_reg;
+	u8	output_frequency_setting_reg;
 	u8	pwm_register_base;
 	bool	pwm_registers_reversed;
 	u8	led_control_register_base;
@@ -90,6 +94,19 @@ static const struct is31fl32xx_chipdef is31fl3236_cdef = {
 	.pwm_update_reg				= 0x25,
 	.global_control_reg			= 0x4a,
 	.reset_reg				= 0x4f,
+	.output_frequency_setting_reg		= IS31FL32XX_REG_NONE,
+	.pwm_register_base			= 0x01,
+	.led_control_register_base		= 0x26,
+	.enable_bits_per_led_control_register	= 1,
+};
+
+static const struct is31fl32xx_chipdef is31fl3236a_cdef = {
+	.channels				= 36,
+	.shutdown_reg				= 0x00,
+	.pwm_update_reg				= 0x25,
+	.global_control_reg			= 0x4a,
+	.reset_reg				= 0x4f,
+	.output_frequency_setting_reg		= 0x4b,
 	.pwm_register_base			= 0x01,
 	.led_control_register_base		= 0x26,
 	.enable_bits_per_led_control_register	= 1,
@@ -101,6 +118,7 @@ static const struct is31fl32xx_chipdef is31fl3235_cdef = {
 	.pwm_update_reg				= 0x25,
 	.global_control_reg			= 0x4a,
 	.reset_reg				= 0x4f,
+	.output_frequency_setting_reg		= IS31FL32XX_REG_NONE,
 	.pwm_register_base			= 0x05,
 	.led_control_register_base		= 0x2a,
 	.enable_bits_per_led_control_register	= 1,
@@ -112,6 +130,7 @@ static const struct is31fl32xx_chipdef is31fl3218_cdef = {
 	.pwm_update_reg				= 0x16,
 	.global_control_reg			= IS31FL32XX_REG_NONE,
 	.reset_reg				= 0x17,
+	.output_frequency_setting_reg		= IS31FL32XX_REG_NONE,
 	.pwm_register_base			= 0x01,
 	.led_control_register_base		= 0x13,
 	.enable_bits_per_led_control_register	= 6,
@@ -126,6 +145,7 @@ static const struct is31fl32xx_chipdef is31fl3216_cdef = {
 	.pwm_update_reg				= 0xB0,
 	.global_control_reg			= IS31FL32XX_REG_NONE,
 	.reset_reg				= IS31FL32XX_REG_NONE,
+	.output_frequency_setting_reg		= IS31FL32XX_REG_NONE,
 	.pwm_register_base			= 0x10,
 	.pwm_registers_reversed			= true,
 	.led_control_register_base		= 0x01,
@@ -363,8 +383,21 @@ static struct is31fl32xx_led_data *is31fl32xx_find_led_data(
 static int is31fl32xx_parse_dt(struct device *dev,
 			       struct is31fl32xx_priv *priv)
 {
+	const struct is31fl32xx_chipdef *cdef = priv->cdef;
 	int ret = 0;
 
+	if ((cdef->output_frequency_setting_reg != IS31FL32XX_REG_NONE) &&
+	    of_property_read_bool(dev_of_node(dev), "issi,22khz-pwm")) {
+
+		ret = is31fl32xx_write(priv, cdef->output_frequency_setting_reg,
+				       IS31FL32XX_PWM_FREQUENCY_22KHZ);
+
+		if (ret) {
+			dev_err(dev, "Failed to write output PWM frequency register\n");
+			return ret;
+		}
+	}
+
 	for_each_available_child_of_node_scoped(dev_of_node(dev), child) {
 		struct led_init_data init_data = {};
 		struct is31fl32xx_led_data *led_data =
@@ -404,12 +437,13 @@ static int is31fl32xx_parse_dt(struct device *dev,
 }
 
 static const struct of_device_id of_is31fl32xx_match[] = {
-	{ .compatible = "issi,is31fl3236", .data = &is31fl3236_cdef, },
-	{ .compatible = "issi,is31fl3235", .data = &is31fl3235_cdef, },
-	{ .compatible = "issi,is31fl3218", .data = &is31fl3218_cdef, },
-	{ .compatible = "si-en,sn3218",    .data = &is31fl3218_cdef, },
-	{ .compatible = "issi,is31fl3216", .data = &is31fl3216_cdef, },
-	{ .compatible = "si-en,sn3216",    .data = &is31fl3216_cdef, },
+	{ .compatible = "issi,is31fl3236",  .data = &is31fl3236_cdef, },
+	{ .compatible = "issi,is31fl3236a", .data = &is31fl3236a_cdef, },
+	{ .compatible = "issi,is31fl3235",  .data = &is31fl3235_cdef, },
+	{ .compatible = "issi,is31fl3218",  .data = &is31fl3218_cdef, },
+	{ .compatible = "si-en,sn3218",     .data = &is31fl3218_cdef, },
+	{ .compatible = "issi,is31fl3216",  .data = &is31fl3216_cdef, },
+	{ .compatible = "si-en,sn3216",     .data = &is31fl3216_cdef, },
 	{},
 };
 
@@ -466,6 +500,7 @@ static void is31fl32xx_remove(struct i2c_client *client)
  */
 static const struct i2c_device_id is31fl32xx_id[] = {
 	{ "is31fl3236" },
+	{ "is31fl3236a" },
 	{ "is31fl3235" },
 	{ "is31fl3218" },
 	{ "sn3218" },