From: John Crispin <blogic@openwrt.org>
Date: Mon, 4 Aug 2014 20:36:29 +0200
Subject: [PATCH 2/2] GPIO: MIPS: ralink: add gpio driver for ralink SoC

Add gpio driver for Ralink SoC. This driver makes the gpio core on
RT2880, RT305x, rt3352, rt3662, rt3883, rt5350 and mt7620 work.

Signed-off-by: John Crispin <blogic@openwrt.org>
---
 drivers/gpio/Kconfig       |   8 ++
 drivers/gpio/Makefile      |   1 +
 drivers/gpio/gpio-ralink.c | 230 +++++++++++++++++++++++++++++++++++++
 3 files changed, 239 insertions(+)
 create mode 100644 drivers/gpio/gpio-ralink.c

--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -555,6 +555,14 @@ config GPIO_PXA
 	help
 	  Say yes here to support the PXA GPIO device.
 
+config GPIO_RALINK
+	bool "Ralink GPIO Support"
+	depends on SOC_RT288X || SOC_RT305X || SOC_RT3883 || SOC_MT7620 
+	select GPIO_GENERIC
+	select GPIOLIB_IRQCHIP
+	help
+	  Say yes here to support the Ralink SoC GPIO device
+
 config GPIO_RCAR
 	tristate "Renesas R-Car and RZ/G GPIO support"
 	depends on ARCH_RENESAS || COMPILE_TEST
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -136,6 +136,7 @@ obj-$(CONFIG_GPIO_PISOSR)		+= gpio-pisos
 obj-$(CONFIG_GPIO_PL061)		+= gpio-pl061.o
 obj-$(CONFIG_GPIO_PMIC_EIC_SPRD)	+= gpio-pmic-eic-sprd.o
 obj-$(CONFIG_GPIO_PXA)			+= gpio-pxa.o
+obj-$(CONFIG_GPIO_RALINK)		+= gpio-ralink.o
 obj-$(CONFIG_GPIO_RASPBERRYPI_EXP)	+= gpio-raspberrypi-exp.o
 obj-$(CONFIG_GPIO_RC5T583)		+= gpio-rc5t583.o
 obj-$(CONFIG_GPIO_RCAR)			+= gpio-rcar.o
--- /dev/null
+++ b/drivers/gpio/gpio-ralink.c
@@ -0,0 +1,230 @@
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>
+ * Copyright (C) 2013 John Crispin <blogic@openwrt.org>
+ */
+
+#include <linux/err.h>
+#include <linux/gpio/driver.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+
+enum ralink_gpio_reg {
+	GPIO_REG_INT = 0,
+	GPIO_REG_EDGE,
+	GPIO_REG_RENA,
+	GPIO_REG_FENA,
+	GPIO_REG_DATA,
+	GPIO_REG_DIR,
+	GPIO_REG_POL,
+	GPIO_REG_SET,
+	GPIO_REG_RESET,
+	GPIO_REG_TOGGLE,
+	GPIO_REG_MAX
+};
+
+struct ralink_gpio_chip {
+	struct gpio_chip chip;
+	u8 regs[GPIO_REG_MAX];
+
+	spinlock_t lock;
+	void __iomem *membase;
+	int gpio_irq;
+
+	u32 rising;
+	u32 falling;
+};
+
+static inline void rt_gpio_w32(struct ralink_gpio_chip *rg, u8 reg, u32 val)
+{
+	iowrite32(val, rg->membase + rg->regs[reg]);
+}
+
+static inline u32 rt_gpio_r32(struct ralink_gpio_chip *rg, u8 reg)
+{
+	return ioread32(rg->membase + rg->regs[reg]);
+}
+
+static irqreturn_t ralink_gpio_irq_handler(int irq, void *data)
+{	
+	struct gpio_chip *gc = data;
+	struct ralink_gpio_chip *rg = gpiochip_get_data(gc);
+	irqreturn_t ret = IRQ_NONE;
+	unsigned long pending;
+	int bit;
+
+	pending = rt_gpio_r32(rg, GPIO_REG_INT);
+	for_each_set_bit(bit, &pending, rg->chip.ngpio) {
+		generic_handle_domain_irq(gc->irq.domain, bit);
+		rt_gpio_w32(rg, GPIO_REG_INT, BIT(bit));
+		ret |= IRQ_HANDLED;
+	}
+
+	return ret;
+}
+
+static void ralink_gpio_irq_unmask(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct ralink_gpio_chip *rg = gpiochip_get_data(gc);
+	unsigned long flags;
+	u32 rise, fall;
+
+	rise = rt_gpio_r32(rg, GPIO_REG_RENA);
+	fall = rt_gpio_r32(rg, GPIO_REG_FENA);
+
+	spin_lock_irqsave(&rg->lock, flags);
+	rt_gpio_w32(rg, GPIO_REG_RENA, rise | (BIT(d->hwirq) & rg->rising));
+	rt_gpio_w32(rg, GPIO_REG_FENA, fall | (BIT(d->hwirq) & rg->falling));
+	spin_unlock_irqrestore(&rg->lock, flags);
+}
+
+static void ralink_gpio_irq_mask(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct ralink_gpio_chip *rg = gpiochip_get_data(gc);
+	unsigned long flags;
+	u32 rise, fall;
+
+	rise = rt_gpio_r32(rg, GPIO_REG_RENA);
+	fall = rt_gpio_r32(rg, GPIO_REG_FENA);
+
+	spin_lock_irqsave(&rg->lock, flags);
+	rt_gpio_w32(rg, GPIO_REG_FENA, fall & ~BIT(d->hwirq));
+	rt_gpio_w32(rg, GPIO_REG_RENA, rise & ~BIT(d->hwirq));
+	spin_unlock_irqrestore(&rg->lock, flags);
+}
+
+static int ralink_gpio_irq_type(struct irq_data *d, unsigned int type)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct ralink_gpio_chip *rg = gpiochip_get_data(gc);
+	u32 mask = BIT(d->hwirq);
+
+	if (type == IRQ_TYPE_PROBE) {
+		if ((rg->rising | rg->falling) & mask)
+			return 0;
+
+		type = IRQ_TYPE_EDGE_RISING | IRQ_TYPE_EDGE_FALLING;
+	}
+
+	if (type & IRQ_TYPE_EDGE_RISING)
+		rg->rising |= mask;
+	else
+		rg->rising &= ~mask;
+
+	if (type & IRQ_TYPE_EDGE_FALLING)
+		rg->falling |= mask;
+	else
+		rg->falling &= ~mask;
+
+	return 0;
+}
+
+static struct irq_chip ralink_gpio_irq_chip = {
+	.name		= "gpio-ralink",
+	.irq_unmask	= ralink_gpio_irq_unmask,
+	.irq_mask	= ralink_gpio_irq_mask,
+	.irq_mask_ack	= ralink_gpio_irq_mask,
+	.irq_set_type	= ralink_gpio_irq_type,
+	.flags		= IRQCHIP_IMMUTABLE,
+	GPIOCHIP_IRQ_RESOURCE_HELPERS,
+};
+
+static int ralink_gpio_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct ralink_gpio_chip *rg;
+	int ret;
+
+	rg = devm_kzalloc(dev, sizeof(struct ralink_gpio_chip), GFP_KERNEL);
+	if (!rg)
+		return -ENOMEM;
+
+	rg->membase = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(rg->membase))
+		return PTR_ERR(rg->membase);
+
+	if (of_property_read_u8_array(np, "ralink,register-map",
+			rg->regs, GPIO_REG_MAX)) {
+		dev_err(dev, "failed to read register definition\n");
+		return -EINVAL;
+	}
+
+	spin_lock_init(&rg->lock);
+
+	ret = bgpio_init(&rg->chip, dev, 4,
+			rg->membase + rg->regs[GPIO_REG_DATA],
+			rg->membase + rg->regs[GPIO_REG_SET],
+			rg->membase + rg->regs[GPIO_REG_RESET],
+			rg->membase + rg->regs[GPIO_REG_DIR],
+			NULL, 0);
+	if (ret)
+		return dev_err_probe(dev, ret, "bgpio_init() failed\n");
+
+	/* set polarity to low for all lines */
+	rt_gpio_w32(rg, GPIO_REG_POL, 0);
+
+	rg->gpio_irq = platform_get_irq(pdev, 0);
+	if (rg->gpio_irq < 0)
+		return rg->gpio_irq;
+
+	if (rg->gpio_irq) {
+		struct gpio_irq_chip *girq;
+
+		/*
+		 * Directly request the irq here instead of passing
+		 * a flow-handler because the irq is shared.
+		 */
+		ret = devm_request_irq(dev, rg->gpio_irq,
+				       ralink_gpio_irq_handler, IRQF_SHARED,
+				       NULL, &rg->chip);
+		if (ret) {
+			dev_err(dev, "Error requesting IRQ %d: %d\n",
+				rg->gpio_irq, ret);
+			return ret;
+		}
+
+		girq = &rg->chip.irq;
+		gpio_irq_chip_set_chip(girq, &ralink_gpio_irq_chip);
+		/* This will let us handle the parent IRQ in the driver */
+		girq->parent_handler = NULL;
+		girq->num_parents = 0;
+		girq->parents = NULL;
+		girq->default_type = IRQ_TYPE_NONE;
+		girq->handler = handle_simple_irq;
+
+		rt_gpio_w32(rg, GPIO_REG_RENA, 0);
+		rt_gpio_w32(rg, GPIO_REG_FENA, 0);
+	}
+
+	return devm_gpiochip_add_data(dev, &rg->chip, rg);
+}
+
+static const struct of_device_id ralink_gpio_match[] = {
+	{ .compatible = "ralink,rt2880-gpio" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, ralink_gpio_match);
+
+static struct platform_driver ralink_gpio_driver = {
+	.probe = ralink_gpio_probe,
+	.driver = {
+		.name = "ralink_gpio",
+		.of_match_table = ralink_gpio_match,
+	},
+};
+
+static int __init ralink_gpio_init(void)
+{
+	return platform_driver_register(&ralink_gpio_driver);
+}
+
+subsys_initcall(ralink_gpio_init);
