gpio/sifive: Add GPIO driver for SiFive SoCs

Adds the GPIO driver for SiFive RISC-V SoCs.

Signed-off-by: Wesley W. Terpstra <[e-mail]>
[Atish: Various fixes and code cleanup]
Signed-off-by: Atish Patra <[e-mail]>
Signed-off-by: Yash Shah <[e-mail]>
Signed-off-by: Marc Zyngier <[e-mail]>
Reviewed-by: Bartosz Golaszewski <[e-mail]>
Reviewed-by: Linus Walleij <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/gpio/Kconfig

···
 	  The difference from regular GPIOs is that they
 	  maintain their value during backup/self-refresh.
 
+config GPIO_SIFIVE
+	bool "SiFive GPIO support"
+	depends on OF_GPIO && IRQ_DOMAIN_HIERARCHY
+	select GPIO_GENERIC
+	select GPIOLIB_IRQCHIP
+	select REGMAP_MMIO
+	help
+	  Say yes here to support the GPIO device on SiFive SoCs.
+
 config GPIO_SIOX
 	tristate "SIOX GPIO support"
 	depends on SIOX

drivers/gpio/Makefile

···
 obj-$(CONFIG_GPIO_SAMA5D2_PIOBU)	+= gpio-sama5d2-piobu.o
 obj-$(CONFIG_GPIO_SCH311X)		+= gpio-sch311x.o
 obj-$(CONFIG_GPIO_SCH)			+= gpio-sch.o
+obj-$(CONFIG_GPIO_SIFIVE)		+= gpio-sifive.o
 obj-$(CONFIG_GPIO_SIOX)			+= gpio-siox.o
 obj-$(CONFIG_GPIO_SODAVILLE)		+= gpio-sodaville.o
 obj-$(CONFIG_GPIO_SPEAR_SPICS)		+= gpio-spear-spics.o

drivers/gpio/gpio-sifive.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 SiFive
+ */
+
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/of_irq.h>
+#include <linux/gpio/driver.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/regmap.h>
+
+#define SIFIVE_GPIO_INPUT_VAL	0x00
+#define SIFIVE_GPIO_INPUT_EN	0x04
+#define SIFIVE_GPIO_OUTPUT_EN	0x08
+#define SIFIVE_GPIO_OUTPUT_VAL	0x0C
+#define SIFIVE_GPIO_RISE_IE	0x18
+#define SIFIVE_GPIO_RISE_IP	0x1C
+#define SIFIVE_GPIO_FALL_IE	0x20
+#define SIFIVE_GPIO_FALL_IP	0x24
+#define SIFIVE_GPIO_HIGH_IE	0x28
+#define SIFIVE_GPIO_HIGH_IP	0x2C
+#define SIFIVE_GPIO_LOW_IE	0x30
+#define SIFIVE_GPIO_LOW_IP	0x34
+#define SIFIVE_GPIO_OUTPUT_XOR	0x40
+
+#define SIFIVE_GPIO_MAX		32
+#define SIFIVE_GPIO_IRQ_OFFSET	7
+
+struct sifive_gpio {
+	void __iomem		*base;
+	struct gpio_chip	gc;
+	struct regmap		*regs;
+	u32			irq_state;
+	unsigned int		trigger[SIFIVE_GPIO_MAX];
+	unsigned int		irq_parent[SIFIVE_GPIO_MAX];
+};
+
+static void sifive_gpio_set_ie(struct sifive_gpio *chip, unsigned int offset)
+{
+	unsigned long flags;
+	unsigned int trigger;
+
+	spin_lock_irqsave(&chip->gc.bgpio_lock, flags);
+	trigger = (chip->irq_state & BIT(offset)) ? chip->trigger[offset] : 0;
+	regmap_update_bits(chip->regs, SIFIVE_GPIO_RISE_IE, BIT(offset),
+			   (trigger & IRQ_TYPE_EDGE_RISING) ? BIT(offset) : 0);
+	regmap_update_bits(chip->regs, SIFIVE_GPIO_FALL_IE, BIT(offset),
+			   (trigger & IRQ_TYPE_EDGE_FALLING) ? BIT(offset) : 0);
+	regmap_update_bits(chip->regs, SIFIVE_GPIO_HIGH_IE, BIT(offset),
+			   (trigger & IRQ_TYPE_LEVEL_HIGH) ? BIT(offset) : 0);
+	regmap_update_bits(chip->regs, SIFIVE_GPIO_LOW_IE, BIT(offset),
+			   (trigger & IRQ_TYPE_LEVEL_LOW) ? BIT(offset) : 0);
+	spin_unlock_irqrestore(&chip->gc.bgpio_lock, flags);
+}
+
+static int sifive_gpio_irq_set_type(struct irq_data *d, unsigned int trigger)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct sifive_gpio *chip = gpiochip_get_data(gc);
+	int offset = irqd_to_hwirq(d);
+
+	if (offset < 0 || offset >= gc->ngpio)
+		return -EINVAL;
+
+	chip->trigger[offset] = trigger;
+	sifive_gpio_set_ie(chip, offset);
+	return 0;
+}
+
+static void sifive_gpio_irq_enable(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct sifive_gpio *chip = gpiochip_get_data(gc);
+	int offset = irqd_to_hwirq(d) % SIFIVE_GPIO_MAX;
+	u32 bit = BIT(offset);
+	unsigned long flags;
+
+	irq_chip_enable_parent(d);
+
+	/* Switch to input */
+	gc->direction_input(gc, offset);
+
+	spin_lock_irqsave(&gc->bgpio_lock, flags);
+	/* Clear any sticky pending interrupts */
+	regmap_write(chip->regs, SIFIVE_GPIO_RISE_IP, bit);
+	regmap_write(chip->regs, SIFIVE_GPIO_FALL_IP, bit);
+	regmap_write(chip->regs, SIFIVE_GPIO_HIGH_IP, bit);
+	regmap_write(chip->regs, SIFIVE_GPIO_LOW_IP, bit);
+	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
+
+	/* Enable interrupts */
+	assign_bit(offset, (unsigned long *)&chip->irq_state, 1);
+	sifive_gpio_set_ie(chip, offset);
+}
+
+static void sifive_gpio_irq_disable(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct sifive_gpio *chip = gpiochip_get_data(gc);
+	int offset = irqd_to_hwirq(d) % SIFIVE_GPIO_MAX;
+
+	assign_bit(offset, (unsigned long *)&chip->irq_state, 0);
+	sifive_gpio_set_ie(chip, offset);
+	irq_chip_disable_parent(d);
+}
+
+static void sifive_gpio_irq_eoi(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct sifive_gpio *chip = gpiochip_get_data(gc);
+	int offset = irqd_to_hwirq(d) % SIFIVE_GPIO_MAX;
+	u32 bit = BIT(offset);
+	unsigned long flags;
+
+	spin_lock_irqsave(&gc->bgpio_lock, flags);
+	/* Clear all pending interrupts */
+	regmap_write(chip->regs, SIFIVE_GPIO_RISE_IP, bit);
+	regmap_write(chip->regs, SIFIVE_GPIO_FALL_IP, bit);
+	regmap_write(chip->regs, SIFIVE_GPIO_HIGH_IP, bit);
+	regmap_write(chip->regs, SIFIVE_GPIO_LOW_IP, bit);
+	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
+
+	irq_chip_eoi_parent(d);
+}
+
+static struct irq_chip sifive_gpio_irqchip = {
+	.name		= "sifive-gpio",
+	.irq_set_type	= sifive_gpio_irq_set_type,
+	.irq_mask	= irq_chip_mask_parent,
+	.irq_unmask	= irq_chip_unmask_parent,
+	.irq_enable	= sifive_gpio_irq_enable,
+	.irq_disable	= sifive_gpio_irq_disable,
+	.irq_eoi	= sifive_gpio_irq_eoi,
+};
+
+static int sifive_gpio_child_to_parent_hwirq(struct gpio_chip *gc,
+					     unsigned int child,
+					     unsigned int child_type,
+					     unsigned int *parent,
+					     unsigned int *parent_type)
+{
+	*parent_type = IRQ_TYPE_NONE;
+	*parent = child + SIFIVE_GPIO_IRQ_OFFSET;
+	return 0;
+}
+
+static const struct regmap_config sifive_gpio_regmap_config = {
+	.reg_bits = 32,
+	.reg_stride = 4,
+	.val_bits = 32,
+	.fast_io = true,
+	.disable_locking = true,
+};
+
+static int sifive_gpio_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *node = pdev->dev.of_node;
+	struct device_node *irq_parent;
+	struct irq_domain *parent;
+	struct gpio_irq_chip *girq;
+	struct sifive_gpio *chip;
+	int ret, ngpio;
+
+	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	chip->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(chip->base)) {
+		dev_err(dev, "failed to allocate device memory\n");
+		return PTR_ERR(chip->base);
+	}
+
+	chip->regs = devm_regmap_init_mmio(dev, chip->base,
+					   &sifive_gpio_regmap_config);
+	if (IS_ERR(chip->regs))
+		return PTR_ERR(chip->regs);
+
+	ngpio = of_irq_count(node);
+	if (ngpio >= SIFIVE_GPIO_MAX) {
+		dev_err(dev, "Too many GPIO interrupts (max=%d)\n",
+			SIFIVE_GPIO_MAX);
+		return -ENXIO;
+	}
+
+	irq_parent = of_irq_find_parent(node);
+	if (!irq_parent) {
+		dev_err(dev, "no IRQ parent node\n");
+		return -ENODEV;
+	}
+	parent = irq_find_host(irq_parent);
+	if (!parent) {
+		dev_err(dev, "no IRQ parent domain\n");
+		return -ENODEV;
+	}
+
+	ret = bgpio_init(&chip->gc, dev, 4,
+			 chip->base + SIFIVE_GPIO_INPUT_VAL,
+			 chip->base + SIFIVE_GPIO_OUTPUT_VAL,
+			 NULL,
+			 chip->base + SIFIVE_GPIO_OUTPUT_EN,
+			 chip->base + SIFIVE_GPIO_INPUT_EN,
+			 0);
+	if (ret) {
+		dev_err(dev, "unable to init generic GPIO\n");
+		return ret;
+	}
+
+	/* Disable all GPIO interrupts before enabling parent interrupts */
+	regmap_write(chip->regs, SIFIVE_GPIO_RISE_IE, 0);
+	regmap_write(chip->regs, SIFIVE_GPIO_FALL_IE, 0);
+	regmap_write(chip->regs, SIFIVE_GPIO_HIGH_IE, 0);
+	regmap_write(chip->regs, SIFIVE_GPIO_LOW_IE, 0);
+	chip->irq_state = 0;
+
+	chip->gc.base = -1;
+	chip->gc.ngpio = ngpio;
+	chip->gc.label = dev_name(dev);
+	chip->gc.parent = dev;
+	chip->gc.owner = THIS_MODULE;
+	girq = &chip->gc.irq;
+	girq->chip = &sifive_gpio_irqchip;
+	girq->fwnode = of_node_to_fwnode(node);
+	girq->parent_domain = parent;
+	girq->child_to_parent_hwirq = sifive_gpio_child_to_parent_hwirq;
+	girq->handler = handle_bad_irq;
+	girq->default_type = IRQ_TYPE_NONE;
+
+	platform_set_drvdata(pdev, chip);
+	return gpiochip_add_data(&chip->gc, chip);
+}
+
+static const struct of_device_id sifive_gpio_match[] = {
+	{ .compatible = "sifive,gpio0" },
+	{ .compatible = "sifive,fu540-c000-gpio" },
+	{ },
+};
+
+static struct platform_driver sifive_gpio_driver = {
+	.probe		= sifive_gpio_probe,
+	.driver = {
+		.name	= "sifive_gpio",
+		.of_match_table = of_match_ptr(sifive_gpio_match),
+	},
+};
+builtin_platform_driver(sifive_gpio_driver)