gpio: Add MT7621 GPIO support

This patch adds GPIO support for the Mediatek MT7621 SoC, tested on
MT7688 (Gardena smart-gateway). The driver is loosly based on the
Linux kernel version.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
[fixed checkpatch.pl warnings: Prefer 'unsigned int' to bare use of 'unsigned']
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>

drivers/gpio/Kconfig

@@ -314,4 +314,12 @@ config MPC8XXX_GPIO
 	  Aside from the standard functions of input/output mode, and output
 	  value setting, the open-drain feature, which can configure individual
 	  GPIOs to work as open-drain outputs, is supported.
+
+config MT7621_GPIO
+	bool "MediaTek MT7621 GPIO driver"
+	depends on DM_GPIO && ARCH_MT7620
+	default y
+	help
+	  Say yes here to support MediaTek MT7621 compatible GPIOs.
+
 endmenu

drivers/gpio/Makefile

@@ -58,3 +58,4 @@ obj-$(CONFIG_MVEBU_GPIO)	+= mvebu_gpio.o
 obj-$(CONFIG_MSM_GPIO)		+= msm_gpio.o
 obj-$(CONFIG_$(SPL_)PCF8575_GPIO)	+= pcf8575_gpio.o
 obj-$(CONFIG_PM8916_GPIO)	+= pm8916_gpio.o
+obj-$(CONFIG_MT7621_GPIO)	+= mt7621_gpio.o

drivers/gpio/mt7621_gpio.c

@@ -0,0 +1,183 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018 Stefan Roese <sr@denx.de>
+ *
+ * Based on the Linux driver version which is:
+ *   Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>
+ *   Copyright (C) 2013 John Crispin <blogic@openwrt.org>
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <fdtdec.h>
+#include <malloc.h>
+#include <linux/io.h>
+#include <asm/io.h>
+#include <asm/gpio.h>
+#include <dm/device-internal.h>
+#include <dt-bindings/gpio/gpio.h>
+
+#define MTK_MAX_BANK		3
+#define MTK_BANK_WIDTH		32
+
+enum mediatek_gpio_reg {
+	GPIO_REG_CTRL = 0,
+	GPIO_REG_POL,
+	GPIO_REG_DATA,
+	GPIO_REG_DSET,
+	GPIO_REG_DCLR,
+	GPIO_REG_REDGE,
+	GPIO_REG_FEDGE,
+	GPIO_REG_HLVL,
+	GPIO_REG_LLVL,
+	GPIO_REG_STAT,
+	GPIO_REG_EDGE,
+};
+
+static void __iomem *mediatek_gpio_membase;
+
+struct mediatek_gpio_platdata {
+	char bank_name[3];	/* Name of bank, e.g. "PA", "PB" etc */
+	int gpio_count;
+	int bank;
+};
+
+static u32 reg_offs(struct mediatek_gpio_platdata *plat, int reg)
+{
+	return (reg * 0x10) + (plat->bank * 0x4);
+}
+
+static int mediatek_gpio_get_value(struct udevice *dev, unsigned int offset)
+{
+	struct mediatek_gpio_platdata *plat = dev_get_platdata(dev);
+
+	return !!(ioread32(mediatek_gpio_membase +
+			   reg_offs(plat, GPIO_REG_DATA)) & BIT(offset));
+}
+
+static int mediatek_gpio_set_value(struct udevice *dev, unsigned int offset,
+				   int value)
+{
+	struct mediatek_gpio_platdata *plat = dev_get_platdata(dev);
+
+	iowrite32(BIT(offset), mediatek_gpio_membase +
+		  reg_offs(plat, value ? GPIO_REG_DSET : GPIO_REG_DCLR));
+
+	return 0;
+}
+
+static int mediatek_gpio_direction_input(struct udevice *dev, unsigned int offset)
+{
+	struct mediatek_gpio_platdata *plat = dev_get_platdata(dev);
+
+	clrbits_le32(mediatek_gpio_membase + reg_offs(plat, GPIO_REG_CTRL),
+		     BIT(offset));
+
+	return 0;
+}
+
+static int mediatek_gpio_direction_output(struct udevice *dev, unsigned int offset,
+					  int value)
+{
+	struct mediatek_gpio_platdata *plat = dev_get_platdata(dev);
+
+	setbits_le32(mediatek_gpio_membase + reg_offs(plat, GPIO_REG_CTRL),
+		     BIT(offset));
+	mediatek_gpio_set_value(dev, offset, value);
+
+	return 0;
+}
+
+static int mediatek_gpio_get_function(struct udevice *dev, unsigned int offset)
+{
+	struct mediatek_gpio_platdata *plat = dev_get_platdata(dev);
+	u32 t;
+
+	t = ioread32(mediatek_gpio_membase + reg_offs(plat, GPIO_REG_CTRL));
+	if (t & BIT(offset))
+		return GPIOF_OUTPUT;
+
+	return GPIOF_INPUT;
+}
+
+static const struct dm_gpio_ops gpio_mediatek_ops = {
+	.direction_input	= mediatek_gpio_direction_input,
+	.direction_output	= mediatek_gpio_direction_output,
+	.get_value		= mediatek_gpio_get_value,
+	.set_value		= mediatek_gpio_set_value,
+	.get_function		= mediatek_gpio_get_function,
+};
+
+static int gpio_mediatek_probe(struct udevice *dev)
+{
+	struct mediatek_gpio_platdata *plat = dev_get_platdata(dev);
+	struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	/* Tell the uclass how many GPIOs we have */
+	if (plat) {
+		uc_priv->gpio_count = plat->gpio_count;
+		uc_priv->bank_name = plat->bank_name;
+	}
+
+	return 0;
+}
+
+/**
+ * We have a top-level GPIO device with no actual GPIOs. It has a child
+ * device for each Mediatek bank.
+ */
+static int gpio_mediatek_bind(struct udevice *parent)
+{
+	struct mediatek_gpio_platdata *plat = parent->platdata;
+	ofnode node;
+	int bank = 0;
+	int ret;
+
+	/* If this is a child device, there is nothing to do here */
+	if (plat)
+		return 0;
+
+	mediatek_gpio_membase = dev_remap_addr(parent);
+	if (!mediatek_gpio_membase)
+		return -EINVAL;
+
+	for (node = dev_read_first_subnode(parent); ofnode_valid(node);
+	     node = dev_read_next_subnode(node)) {
+		struct mediatek_gpio_platdata *plat;
+		struct udevice *dev;
+
+		plat = calloc(1, sizeof(*plat));
+		if (!plat)
+			return -ENOMEM;
+		plat->bank_name[0] = 'P';
+		plat->bank_name[1] = 'A' + bank;
+		plat->bank_name[2] = '\0';
+		plat->gpio_count = MTK_BANK_WIDTH;
+		plat->bank = bank;
+
+		ret = device_bind(parent, parent->driver,
+				  plat->bank_name, plat, -1, &dev);
+		if (ret)
+			return ret;
+
+		dev->node = node;
+		bank++;
+	}
+
+	return 0;
+}
+
+static const struct udevice_id mediatek_gpio_ids[] = {
+	{ .compatible = "mtk,mt7621-gpio" },
+	{ }
+};
+
+U_BOOT_DRIVER(gpio_mediatek) = {
+	.name	= "gpio_mediatek",
+	.id	= UCLASS_GPIO,
+	.ops	= &gpio_mediatek_ops,
+	.of_match = mediatek_gpio_ids,
+	.bind	= gpio_mediatek_bind,
+	.probe	= gpio_mediatek_probe,
+};