gpio: add sl28cpld driver

The gpio block is part of the sl28cpld sl28cpld management controller.
There are three different flavors: the usual input and output where the
direction is configurable, but also input only and output only variants.

Signed-off-by: Michael Walle <michael@walle.cc>
[Rebased]
Signed-off-by: Priyanka Jain <priyanka.jain@nxp.com>

MAINTAINERS

@@ -1164,6 +1164,7 @@ F:	arch/sh/
 SL28CLPD
 M:	Michael Walle <michael@walle.cc>
 S:	Maintained
+F:	drivers/gpio/sl28cpld-gpio.c
 F:	drivers/misc/sl28cpld.c
 F:	drivers/watchdog/sl28cpld-wdt.c
 

drivers/gpio/Kconfig

@@ -544,4 +544,10 @@ config ZYNQMP_GPIO_MODEPIN
 	  are accessed using xilinx firmware. In modepin register, [3:0] bits
 	  set direction, [7:4] bits read IO, [11:8] bits set/clear IO.
 
+config SL28CPLD_GPIO
+	bool "Kontron sl28cpld GPIO driver"
+	depends on DM_GPIO && SL28CPLD
+	help
+	  Support GPIO access on Kontron sl28cpld board management controllers.
+
 endif

drivers/gpio/Makefile

@@ -70,4 +70,5 @@ obj-$(CONFIG_NX_GPIO)		+= nx_gpio.o
 obj-$(CONFIG_SIFIVE_GPIO)	+= sifive-gpio.o
 obj-$(CONFIG_NOMADIK_GPIO)	+= nmk_gpio.o
 obj-$(CONFIG_MAX7320_GPIO)	+= max7320_gpio.o
+obj-$(CONFIG_SL28CPLD_GPIO)	+= sl28cpld-gpio.o
 obj-$(CONFIG_ZYNQMP_GPIO_MODEPIN)	+= zynqmp_gpio_modepin.o

drivers/gpio/sl28cpld-gpio.c

@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * GPIO driver for the sl28cpld
+ *
+ * Copyright (c) 2021 Michael Walle <michael@walle.cc>
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <asm/gpio.h>
+#include <sl28cpld.h>
+
+/* GPIO flavor */
+#define SL28CPLD_GPIO_DIR	0x00
+#define SL28CPLD_GPIO_OUT	0x01
+#define SL28CPLD_GPIO_IN	0x02
+
+/* input-only flavor */
+#define SL28CPLD_GPI_IN		0x00
+
+/* output-only flavor */
+#define SL28CPLD_GPO_OUT	0x00
+
+enum {
+	SL28CPLD_GPIO,
+	SL28CPLD_GPI,
+	SL28CPLD_GPO,
+};
+
+static int sl28cpld_gpio_get_value(struct udevice *dev, unsigned int gpio)
+{
+	ulong type = dev_get_driver_data(dev);
+	int val, reg;
+
+	switch (type) {
+	case SL28CPLD_GPIO:
+		reg = SL28CPLD_GPIO_IN;
+		break;
+	case SL28CPLD_GPI:
+		reg = SL28CPLD_GPI_IN;
+		break;
+	case SL28CPLD_GPO:
+		/* we are output only, thus just return the output value */
+		reg = SL28CPLD_GPO_OUT;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	val = sl28cpld_read(dev, reg);
+
+	return val < 0 ? val : !!(val & BIT(gpio));
+}
+
+static int sl28cpld_gpio_set_value(struct udevice *dev, unsigned int gpio,
+				   int value)
+{
+	ulong type = dev_get_driver_data(dev);
+	uint reg;
+
+	switch (type) {
+	case SL28CPLD_GPIO:
+		reg = SL28CPLD_GPIO_OUT;
+		break;
+	case SL28CPLD_GPO:
+		reg = SL28CPLD_GPO_OUT;
+		break;
+	case SL28CPLD_GPI:
+	default:
+		return -EINVAL;
+	}
+
+	if (value)
+		return sl28cpld_update(dev, reg, 0, BIT(gpio));
+	else
+		return sl28cpld_update(dev, reg, BIT(gpio), 0);
+}
+
+static int sl28cpld_gpio_direction_input(struct udevice *dev, unsigned int gpio)
+{
+	ulong type = dev_get_driver_data(dev);
+
+	switch (type) {
+	case SL28CPLD_GPI:
+		return 0;
+	case SL28CPLD_GPIO:
+		return sl28cpld_update(dev, SL28CPLD_GPIO_DIR, BIT(gpio), 0);
+	case SL28CPLD_GPO:
+	default:
+		return -EINVAL;
+	}
+}
+
+static int sl28cpld_gpio_direction_output(struct udevice *dev,
+					  unsigned int gpio, int value)
+{
+	ulong type = dev_get_driver_data(dev);
+	int ret;
+
+	/* set_value() will report an error if we are input-only */
+	ret = sl28cpld_gpio_set_value(dev, gpio, value);
+	if (ret)
+		return ret;
+
+	if (type == SL28CPLD_GPIO)
+		return sl28cpld_update(dev, SL28CPLD_GPIO_DIR, 0, BIT(gpio));
+
+	return 0;
+}
+
+static int sl28cpld_gpio_get_function(struct udevice *dev, unsigned int gpio)
+{
+	ulong type = dev_get_driver_data(dev);
+	int val;
+
+	switch (type) {
+	case SL28CPLD_GPIO:
+		val = sl28cpld_read(dev, SL28CPLD_GPIO_DIR);
+		if (val < 0)
+			return val;
+		if (val & BIT(gpio))
+			return GPIOF_OUTPUT;
+		else
+			return GPIOF_INPUT;
+	case SL28CPLD_GPI:
+		return GPIOF_INPUT;
+	case SL28CPLD_GPO:
+		return GPIOF_OUTPUT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct dm_gpio_ops sl28cpld_gpio_ops = {
+	.direction_input = sl28cpld_gpio_direction_input,
+	.direction_output = sl28cpld_gpio_direction_output,
+	.get_value = sl28cpld_gpio_get_value,
+	.set_value = sl28cpld_gpio_set_value,
+	.get_function = sl28cpld_gpio_get_function,
+};
+
+static int sl28cpld_gpio_probe(struct udevice *dev)
+{
+	struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	uc_priv->gpio_count = 8;
+	uc_priv->bank_name = dev_read_name(dev);
+
+	return 0;
+}
+
+static const struct udevice_id sl28cpld_gpio_ids[] = {
+	{ .compatible = "kontron,sl28cpld-gpio", .data = SL28CPLD_GPIO},
+	{ .compatible = "kontron,sl28cpld-gpo", .data = SL28CPLD_GPO},
+	{ .compatible = "kontron,sl28cpld-gpi", .data = SL28CPLD_GPI},
+	{ }
+};
+
+U_BOOT_DRIVER(sl28cpld_gpio) = {
+	.name	= "sl28cpld_gpio",
+	.id	= UCLASS_GPIO,
+	.of_match = sl28cpld_gpio_ids,
+	.probe	= sl28cpld_gpio_probe,
+	.ops	= &sl28cpld_gpio_ops,
+};