gpio: Add a driver for Cortina Systems Gemini GPIO

This is a heavy edit/rewrite of the GPIO driver for the Gemini
SoC from arch/arm/mach-gemini/gpio.c.

This rewrite uses all the best-in-class helper like generic
GPIO and GPIOLIB_IRQCHIP and has been tested on ITian Square One
Gemini-based NAS/router.

Cc: Janos Laube <janos.dev@gmail.com>
Cc: Paulius Zaleckas <paulius.zaleckas@gmail.com>
Cc: Hans Ulli Kroll <ulli.kroll@googlemail.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/Kconfig

@@ -197,6 +197,15 @@ config GPIO_GE_FPGA
 	  and write pin state) for GPIO implemented in a number of GE single
 	  board computers.
 
+config GPIO_GEMINI
+	bool "Gemini GPIO"
+	depends on ARCH_GEMINI
+	depends on OF_GPIO
+	select GPIO_GENERIC
+	select GPIOLIB_IRQCHIP
+	help
+	  Support for common GPIOs found in Cortina systems Gemini platforms.
+
 config GPIO_GENERIC_PLATFORM
 	tristate "Generic memory-mapped GPIO controller support (MMIO platform device)"
 	select GPIO_GENERIC

drivers/gpio/Makefile

@@ -48,6 +48,7 @@ obj-$(CONFIG_GPIO_EP93XX)	+= gpio-ep93xx.o
 obj-$(CONFIG_GPIO_ETRAXFS)	+= gpio-etraxfs.o
 obj-$(CONFIG_GPIO_F7188X)	+= gpio-f7188x.o
 obj-$(CONFIG_GPIO_GE_FPGA)	+= gpio-ge.o
+obj-$(CONFIG_GPIO_GEMINI)	+= gpio-gemini.o
 obj-$(CONFIG_GPIO_GPIO_MM)	+= gpio-gpio-mm.o
 obj-$(CONFIG_GPIO_GRGPIO)	+= gpio-grgpio.o
 obj-$(CONFIG_HTC_EGPIO)		+= gpio-htc-egpio.o

drivers/gpio/gpio-gemini.c

+/*
+ * Gemini gpiochip and interrupt routines
+ * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
+ *
+ * Based on arch/arm/mach-gemini/gpio.c:
+ * Copyright (C) 2008-2009 Paulius Zaleckas <paulius.zaleckas@teltonika.lt>
+ *
+ * Based on plat-mxc/gpio.c:
+ * MXC GPIO support. (c) 2008 Daniel Mack <daniel@caiaq.de>
+ * Copyright 2008 Juergen Beisert, kernel@pengutronix.de
+ */
+#include <linux/gpio/driver.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/of_gpio.h>
+#include <linux/bitops.h>
+
+/* GPIO registers definition */
+#define GPIO_DATA_OUT		0x00
+#define GPIO_DATA_IN		0x04
+#define GPIO_DIR		0x08
+#define GPIO_DATA_SET		0x10
+#define GPIO_DATA_CLR		0x14
+#define GPIO_PULL_EN		0x18
+#define GPIO_PULL_TYPE		0x1C
+#define GPIO_INT_EN		0x20
+#define GPIO_INT_STAT		0x24
+#define GPIO_INT_MASK		0x2C
+#define GPIO_INT_CLR		0x30
+#define GPIO_INT_TYPE		0x34
+#define GPIO_INT_BOTH_EDGE	0x38
+#define GPIO_INT_LEVEL		0x3C
+#define GPIO_DEBOUNCE_EN	0x40
+#define GPIO_DEBOUNCE_PRESCALE	0x44
+
+/**
+ * struct gemini_gpio - Gemini GPIO state container
+ * @dev: containing device for this instance
+ * @gc: gpiochip for this instance
+ */
+struct gemini_gpio {
+	struct device *dev;
+	struct gpio_chip gc;
+	void __iomem *base;
+};
+
+static void gemini_gpio_ack_irq(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct gemini_gpio *g = gpiochip_get_data(gc);
+
+	writel(BIT(irqd_to_hwirq(d)), g->base + GPIO_INT_CLR);
+}
+
+static void gemini_gpio_mask_irq(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct gemini_gpio *g = gpiochip_get_data(gc);
+	u32 val;
+
+	val = readl(g->base + GPIO_INT_EN);
+	val &= ~BIT(irqd_to_hwirq(d));
+	writel(val, g->base + GPIO_INT_EN);
+}
+
+static void gemini_gpio_unmask_irq(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct gemini_gpio *g = gpiochip_get_data(gc);
+	u32 val;
+
+	val = readl(g->base + GPIO_INT_EN);
+	val |= BIT(irqd_to_hwirq(d));
+	writel(val, g->base + GPIO_INT_EN);
+}
+
+static int gemini_gpio_set_irq_type(struct irq_data *d, unsigned int type)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct gemini_gpio *g = gpiochip_get_data(gc);
+	u32 mask = BIT(irqd_to_hwirq(d));
+	u32 reg_both, reg_level, reg_type;
+
+	reg_type = readl(g->base + GPIO_INT_TYPE);
+	reg_level = readl(g->base + GPIO_INT_LEVEL);
+	reg_both = readl(g->base + GPIO_INT_BOTH_EDGE);
+
+	switch (type) {
+	case IRQ_TYPE_EDGE_BOTH:
+		irq_set_handler_locked(d, handle_edge_irq);
+		reg_type &= ~mask;
+		reg_both |= mask;
+		break;
+	case IRQ_TYPE_EDGE_RISING:
+		irq_set_handler_locked(d, handle_edge_irq);
+		reg_type &= ~mask;
+		reg_both &= ~mask;
+		reg_level &= ~mask;
+		break;
+	case IRQ_TYPE_EDGE_FALLING:
+		irq_set_handler_locked(d, handle_edge_irq);
+		reg_type &= ~mask;
+		reg_both &= ~mask;
+		reg_level |= mask;
+		break;
+	case IRQ_TYPE_LEVEL_HIGH:
+		irq_set_handler_locked(d, handle_level_irq);
+		reg_type |= mask;
+		reg_level &= ~mask;
+		break;
+	case IRQ_TYPE_LEVEL_LOW:
+		irq_set_handler_locked(d, handle_level_irq);
+		reg_type |= mask;
+		reg_level |= mask;
+		break;
+	default:
+		irq_set_handler_locked(d, handle_bad_irq);
+		return -EINVAL;
+	}
+
+	writel(reg_type, g->base + GPIO_INT_TYPE);
+	writel(reg_level, g->base + GPIO_INT_LEVEL);
+	writel(reg_both, g->base + GPIO_INT_BOTH_EDGE);
+
+	gemini_gpio_ack_irq(d);
+
+	return 0;
+}
+
+static struct irq_chip gemini_gpio_irqchip = {
+	.name = "GPIO",
+	.irq_ack = gemini_gpio_ack_irq,
+	.irq_mask = gemini_gpio_mask_irq,
+	.irq_unmask = gemini_gpio_unmask_irq,
+	.irq_set_type = gemini_gpio_set_irq_type,
+};
+
+static void gemini_gpio_irq_handler(struct irq_desc *desc)
+{
+	struct gpio_chip *gc = irq_desc_get_handler_data(desc);
+	struct gemini_gpio *g = gpiochip_get_data(gc);
+	struct irq_chip *irqchip = irq_desc_get_chip(desc);
+	int offset;
+	unsigned long stat;
+
+	chained_irq_enter(irqchip, desc);
+
+	stat = readl(g->base + GPIO_INT_STAT);
+	if (stat)
+		for_each_set_bit(offset, &stat, gc->ngpio)
+			generic_handle_irq(irq_find_mapping(gc->irqdomain,
+							    offset));
+
+	chained_irq_exit(irqchip, desc);
+}
+
+static int gemini_gpio_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	struct gemini_gpio *g;
+	int irq;
+	int ret;
+
+	g = devm_kzalloc(dev, sizeof(*g), GFP_KERNEL);
+	if (!g)
+		return -ENOMEM;
+
+	g->dev = dev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	g->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(g->base))
+		return PTR_ERR(g->base);
+
+	irq = platform_get_irq(pdev, 0);
+	if (!irq)
+		return -EINVAL;
+
+	ret = bgpio_init(&g->gc, dev, 4,
+			 g->base + GPIO_DATA_IN,
+			 g->base + GPIO_DATA_SET,
+			 g->base + GPIO_DATA_CLR,
+			 g->base + GPIO_DIR,
+			 NULL,
+			 0);
+	if (ret) {
+		dev_err(dev, "unable to init generic GPIO\n");
+		return ret;
+	}
+	g->gc.label = "Gemini";
+	g->gc.base = -1;
+	g->gc.parent = dev;
+	g->gc.owner = THIS_MODULE;
+	/* ngpio is set by bgpio_init() */
+
+	ret = devm_gpiochip_add_data(dev, &g->gc, g);
+	if (ret)
+		return ret;
+
+	/* Disable, unmask and clear all interrupts */
+	writel(0x0, g->base + GPIO_INT_EN);
+	writel(0x0, g->base + GPIO_INT_MASK);
+	writel(~0x0, g->base + GPIO_INT_CLR);
+
+	ret = gpiochip_irqchip_add(&g->gc, &gemini_gpio_irqchip,
+				   0, handle_bad_irq,
+				   IRQ_TYPE_NONE);
+	if (ret) {
+		dev_info(dev, "could not add irqchip\n");
+		return ret;
+	}
+	gpiochip_set_chained_irqchip(&g->gc, &gemini_gpio_irqchip,
+				     irq, gemini_gpio_irq_handler);
+
+	dev_info(dev, "Gemini GPIO @%p registered\n", g->base);
+
+	return 0;
+}
+
+static const struct of_device_id gemini_gpio_of_match[] = {
+	{
+		.compatible = "cortina,gemini-gpio",
+	},
+	{},
+};
+
+static struct platform_driver gemini_gpio_driver = {
+	.driver = {
+		.name		= "gemini-gpio",
+		.of_match_table = of_match_ptr(gemini_gpio_of_match),
+	},
+	.probe	= gemini_gpio_probe,
+};
+builtin_platform_driver(gemini_gpio_driver);