realtek: Add pinctrl support for RTL8231

Add pending patches to add RTL8231 support as a MDIO-bus attached
multi-functional device. This includes subdrivers for the pincontrol and
GPIO features, as well as the LED matrix support.

Leave the drivers disabled until required by a device.

Signed-off-by: Sander Vanheule <[email protected]>

target/linux/realtek/patches-6.6/800-gpio-regmap-Bypass-cache-for-shadowed-outputs.patch

@@ -0,0 +1,56 @@
+From b3f79468c90d8770f007d628a1e32b2d5d44a5c2 Mon Sep 17 00:00:00 2001
+From: Sander Vanheule <[email protected]>
+Date: Sat, 15 May 2021 11:57:32 +0200
+Subject: [PATCH] gpio: regmap: Bypass cache for shadowed outputs
+
+Some chips have the read-only input and write-only output data registers
+aliased to the same offset, but do not perform direction multiplexing on
+writes. Upon writing the register, this then always updates the output
+value, even when the pin is configured as input. As a result it is not
+safe to perform read-modify-writes on output pins, when other pins are
+still configured as input.
+
+For example, on a bit-banged I2C bus, where the lines are switched
+between out-low and in (with external pull-up)
+
+    OUT(L) IN     OUT(H)
+SCK ....../''''''|''''''
+
+SDA '''''''''\..........
+             ^   ^- SCK switches to direction to OUT, but now has a high
+             |      value, breaking the clock.
+             |
+             \- Perform RMW to update SDA. This reads the current input
+                value for SCK, updates the SDA value and writes back a 1
+                for SCK as well.
+
+If a register is used for both the data input and data output (and is
+not marked as volatile) the driver should ensure the cache is not
+updated on register reads. This ensures proper functioning of writing
+the output register with regmap_update_bits(), which will then use and
+update the cache only on register writes.
+
+Signed-off-by: Sander Vanheule <[email protected]>
+---
+ drivers/gpio/gpio-regmap.c | 10 +++++++++-
+ 1 file changed, 9 insertions(+), 1 deletion(-)
+
+--- a/drivers/gpio/gpio-regmap.c
++++ b/drivers/gpio/gpio-regmap.c
+@@ -74,7 +74,15 @@ static int gpio_regmap_get(struct gpio_c
+ 	if (ret)
+ 		return ret;
+
+-	ret = regmap_read(gpio->regmap, reg, &val);
++	/*
++	 * Ensure we don't spoil the register cache with pin input values and
++	 * perform a bypassed read. This way the cache (if any) is only used and
++	 * updated on register writes.
++	 */
++	if (gpio->reg_dat_base == gpio->reg_set_base)
++		ret = regmap_read_bypassed(gpio->regmap, reg, &val);
++	else
++		ret = regmap_read(gpio->regmap, reg, &val);
+ 	if (ret)
+ 		return ret;
+

target/linux/realtek/patches-6.6/801-gpio-regmap-Use-generic-request-free-ops.patch

@@ -0,0 +1,26 @@
+From f21b15dfe254b51f80c552750eb20b1dc752507a Mon Sep 17 00:00:00 2001
+From: Sander Vanheule <[email protected]>
+Date: Mon, 30 Dec 2024 17:59:24 +0100
+Subject: [PATCH] gpio: regmap: Use generic request/free ops
+
+Set the gpiochip request and free ops to the generic implementations.
+This way a user can provide a gpio-ranges property defined for a pinmux,
+allowing pins to automatically be muxed to their GPIO function when
+requested.
+
+Signed-off-by: Sander Vanheule <[email protected]>
+---
+ drivers/gpio/gpio-regmap.c | 2 ++
+ 1 file changed, 2 insertions(+)
+
+--- a/drivers/gpio/gpio-regmap.c
++++ b/drivers/gpio/gpio-regmap.c
+@@ -270,6 +270,8 @@ struct gpio_regmap *gpio_regmap_register
+ 	chip->label = config->label ?: dev_name(config->parent);
+ 	chip->can_sleep = regmap_might_sleep(config->regmap);
+
++	chip->request = gpiochip_generic_request;
++	chip->free = gpiochip_generic_free;
+ 	chip->get = gpio_regmap_get;
+ 	if (gpio->reg_set_base && gpio->reg_clr_base)
+ 		chip->set = gpio_regmap_set_with_clear;