[PATCH v2 2/2] gpio: Add Cadence GPIO driver

[Jan Kotas <jank@xxxxxxxxxxx>]

This patch adds a driver for Cadence GPIO controller.

It can be enabled with GPIO_CADENCE Kconfig option.
It uses generic GPIO infrastructure and works
as an interrupt controller.
At the moment it only supports level sensitive irqs.

Signed-off-by: Jan Kotas <jank@xxxxxxxxxxx>
---
 drivers/gpio/Kconfig        |   8 ++
 drivers/gpio/Makefile       |   1 +
 drivers/gpio/gpio-cadence.c | 275 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 284 insertions(+)
 create mode 100644 drivers/gpio/gpio-cadence.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 833a1b51c..8259f8f25 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -160,6 +160,14 @@ config GPIO_BRCMSTB
 	help
 	  Say yes here to enable GPIO support for Broadcom STB (BCM7XXX) SoCs.
 
+config GPIO_CADENCE
+	tristate "Cadence GPIO support"
+	depends on OF_GPIO
+	select GPIO_GENERIC
+	select GPIOLIB_IRQCHIP
+	help
+	  Say yes here to enable support for Cadence GPIO controller.
+
 config GPIO_CLPS711X
 	tristate "CLPS711X GPIO support"
 	depends on ARCH_CLPS711X || COMPILE_TEST
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 671c4477c..5fce8634a 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -37,6 +37,7 @@ obj-$(CONFIG_GPIO_BCM_KONA)	+= gpio-bcm-kona.o
 obj-$(CONFIG_GPIO_BD9571MWV)	+= gpio-bd9571mwv.o
 obj-$(CONFIG_GPIO_BRCMSTB)	+= gpio-brcmstb.o
 obj-$(CONFIG_GPIO_BT8XX)	+= gpio-bt8xx.o
+obj-$(CONFIG_GPIO_CADENCE)	+= gpio-cadence.o
 obj-$(CONFIG_GPIO_CLPS711X)	+= gpio-clps711x.o
 obj-$(CONFIG_GPIO_CS5535)	+= gpio-cs5535.o
 obj-$(CONFIG_GPIO_CRYSTAL_COVE)	+= gpio-crystalcove.o
diff --git a/drivers/gpio/gpio-cadence.c b/drivers/gpio/gpio-cadence.c
new file mode 100644
index 000000000..16cc9f50f
--- /dev/null
+++ b/drivers/gpio/gpio-cadence.c
@@ -0,0 +1,275 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright 2017-2018 Cadence
+ *
+ * Authors:
+ *  Jan Kotas <jank@xxxxxxxxxxx>
+ *  Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
+ */
+
+#include <linux/gpio/driver.h>
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define CDNS_GPIO_BYPASS_MODE		0x00
+#define CDNS_GPIO_DIRECTION_MODE	0x04
+#define CDNS_GPIO_OUTPUT_EN		0x08
+#define CDNS_GPIO_OUTPUT_VALUE		0x0c
+#define CDNS_GPIO_INPUT_VALUE		0x10
+#define CDNS_GPIO_IRQ_MASK		0x14
+#define CDNS_GPIO_IRQ_EN		0x18
+#define CDNS_GPIO_IRQ_DIS		0x1c
+#define CDNS_GPIO_IRQ_STATUS		0x20
+#define CDNS_GPIO_IRQ_TYPE		0x24
+#define CDNS_GPIO_IRQ_VALUE		0x28
+#define CDNS_GPIO_IRQ_ANY_EDGE		0x2c
+
+struct cdns_gpio_chip {
+	struct gpio_chip gc;
+	struct clk *pclk;
+	void __iomem *regs;
+	u32 bypass_orig;
+};
+
+static int cdns_gpio_request(struct gpio_chip *chip, unsigned int offset)
+{
+	struct cdns_gpio_chip *cgpio = gpiochip_get_data(chip);
+
+	iowrite32(ioread32(cgpio->regs + CDNS_GPIO_BYPASS_MODE) & ~BIT(offset),
+		  cgpio->regs + CDNS_GPIO_BYPASS_MODE);
+
+	return 0;
+}
+
+static void cdns_gpio_free(struct gpio_chip *chip, unsigned int offset)
+{
+	struct cdns_gpio_chip *cgpio = gpiochip_get_data(chip);
+
+	iowrite32(ioread32(cgpio->regs + CDNS_GPIO_BYPASS_MODE) |
+		  (BIT(offset) & cgpio->bypass_orig),
+		  cgpio->regs + CDNS_GPIO_BYPASS_MODE);
+}
+
+static void cdns_gpio_irq_mask(struct irq_data *d)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
+	struct cdns_gpio_chip *cgpio = gpiochip_get_data(chip);
+
+	iowrite32(BIT(d->hwirq), cgpio->regs + CDNS_GPIO_IRQ_DIS);
+}
+
+static void cdns_gpio_irq_unmask(struct irq_data *d)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
+	struct cdns_gpio_chip *cgpio = gpiochip_get_data(chip);
+
+	iowrite32(BIT(d->hwirq), cgpio->regs + CDNS_GPIO_IRQ_EN);
+}
+
+static int cdns_gpio_irq_set_type(struct irq_data *d, unsigned int type)
+{
+	struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
+	struct cdns_gpio_chip *cgpio = gpiochip_get_data(chip);
+	u32 int_value = ioread32(cgpio->regs + CDNS_GPIO_IRQ_VALUE);
+	u32 int_type = ioread32(cgpio->regs + CDNS_GPIO_IRQ_TYPE);
+	u32 mask = BIT(d->hwirq);
+
+	int_value &= ~mask;
+	int_type &= ~mask;
+
+	/*
+	 * The GPIO controller doesn't have an ACK register.
+	 * All interrupt statuses are cleared on a status register read.
+	 * Don't support edge interrupts for now.
+	 */
+
+	if (type == IRQ_TYPE_LEVEL_HIGH) {
+		int_type |= mask;
+		int_value |= mask;
+	} else if (type == IRQ_TYPE_LEVEL_LOW) {
+		int_type |= mask;
+	} else {
+		return -EINVAL;
+	}
+
+	iowrite32(int_value, cgpio->regs + CDNS_GPIO_IRQ_VALUE);
+	iowrite32(int_type, cgpio->regs + CDNS_GPIO_IRQ_TYPE);
+
+	return 0;
+}
+
+static void cdns_gpio_irq_handler(struct irq_desc *desc)
+{
+	struct gpio_chip *chip = irq_desc_get_handler_data(desc);
+	struct cdns_gpio_chip *cgpio = gpiochip_get_data(chip);
+	struct irq_chip *irqchip = irq_desc_get_chip(desc);
+	unsigned long status;
+	int hwirq;
+
+	chained_irq_enter(irqchip, desc);
+
+	status = ioread32(cgpio->regs + CDNS_GPIO_IRQ_STATUS) &
+		~ioread32(cgpio->regs + CDNS_GPIO_IRQ_MASK);
+
+	for_each_set_bit(hwirq, &status, chip->ngpio)
+		generic_handle_irq(irq_find_mapping(chip->irq.domain, hwirq));
+
+	chained_irq_exit(irqchip, desc);
+}
+
+static struct irq_chip cdns_gpio_irqchip = {
+	.name		= "cdns-gpio",
+	.irq_mask	= cdns_gpio_irq_mask,
+	.irq_unmask	= cdns_gpio_irq_unmask,
+	.irq_set_type	= cdns_gpio_irq_set_type
+};
+
+static int cdns_gpio_probe(struct platform_device *pdev)
+{
+	struct cdns_gpio_chip *cgpio;
+	struct resource *res;
+	int ret, irq;
+	u32 dir_prev;
+	u32 num_gpios = 32;
+
+	cgpio = devm_kzalloc(&pdev->dev, sizeof(*cgpio), GFP_KERNEL);
+	if (!cgpio)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	cgpio->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(cgpio->regs))
+		return PTR_ERR(cgpio->regs);
+
+	of_property_read_u32(pdev->dev.of_node, "ngpios", &num_gpios);
+
+	if (num_gpios > 32) {
+		dev_err(&pdev->dev, "ngpios must be less or equal 32\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * Set all pins as inputs by default, otherwise:
+	 * gpiochip_lock_as_irq:
+	 * tried to flag a GPIO set as output for IRQ
+	 * Generic GPIO driver stores the direction value internally,
+	 * so it needs to be changed before bgpio_init() is called.
+	 */
+	dir_prev = ioread32(cgpio->regs + CDNS_GPIO_DIRECTION_MODE);
+	iowrite32(GENMASK(num_gpios - 1, 0),
+		  cgpio->regs + CDNS_GPIO_DIRECTION_MODE);
+
+	ret = bgpio_init(&cgpio->gc, &pdev->dev, 4,
+			 cgpio->regs + CDNS_GPIO_INPUT_VALUE,
+			 cgpio->regs + CDNS_GPIO_OUTPUT_VALUE,
+			 NULL,
+			 NULL,
+			 cgpio->regs + CDNS_GPIO_DIRECTION_MODE,
+			 BGPIOF_READ_OUTPUT_REG_SET);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to register generic gpio, %d\n",
+			ret);
+		goto err_revert_dir;
+	}
+
+	cgpio->gc.label = dev_name(&pdev->dev);
+	cgpio->gc.ngpio = num_gpios;
+	cgpio->gc.parent = &pdev->dev;
+	cgpio->gc.base = -1;
+	cgpio->gc.owner = THIS_MODULE;
+	cgpio->gc.request = cdns_gpio_request;
+	cgpio->gc.free = cdns_gpio_free;
+
+	cgpio->pclk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(cgpio->pclk)) {
+		ret = PTR_ERR(cgpio->pclk);
+		dev_err(&pdev->dev,
+			"Failed to retrieve peripheral clock, %d\n", ret);
+		goto err_revert_dir;
+	}
+
+	ret = clk_prepare_enable(cgpio->pclk);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"Failed to enable the peripheral clock, %d\n", ret);
+		goto err_revert_dir;
+	}
+
+	ret = devm_gpiochip_add_data(&pdev->dev, &cgpio->gc, cgpio);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Could not register gpiochip, %d\n", ret);
+		goto err_disable_clk;
+	}
+
+	/*
+	 * irq_chip support
+	 */
+	irq = platform_get_irq(pdev, 0);
+	if (irq >= 0) {
+		ret = gpiochip_irqchip_add(&cgpio->gc, &cdns_gpio_irqchip,
+					   0, handle_level_irq,
+					   IRQ_TYPE_NONE);
+		if (ret) {
+			dev_err(&pdev->dev, "Could not add irqchip, %d\n",
+				ret);
+			goto err_disable_clk;
+		}
+		gpiochip_set_chained_irqchip(&cgpio->gc, &cdns_gpio_irqchip,
+					     irq, cdns_gpio_irq_handler);
+	}
+
+	cgpio->bypass_orig = ioread32(cgpio->regs + CDNS_GPIO_BYPASS_MODE);
+
+	/*
+	 * Enable gpio outputs, ignored for input direction
+	 */
+	iowrite32(GENMASK(num_gpios - 1, 0),
+		  cgpio->regs + CDNS_GPIO_OUTPUT_EN);
+	iowrite32(0, cgpio->regs + CDNS_GPIO_BYPASS_MODE);
+
+	platform_set_drvdata(pdev, cgpio);
+	return 0;
+
+err_disable_clk:
+	clk_disable_unprepare(cgpio->pclk);
+
+err_revert_dir:
+	iowrite32(dir_prev, cgpio->regs + CDNS_GPIO_DIRECTION_MODE);
+
+	return ret;
+}
+
+static int cdns_gpio_remove(struct platform_device *pdev)
+{
+	struct cdns_gpio_chip *cgpio = platform_get_drvdata(pdev);
+
+	iowrite32(cgpio->bypass_orig, cgpio->regs + CDNS_GPIO_BYPASS_MODE);
+	clk_disable_unprepare(cgpio->pclk);
+
+	return 0;
+}
+
+static const struct of_device_id cdns_of_ids[] = {
+	{ .compatible = "cdns,gpio-r1p02" },
+	{ /* sentinel */ },
+};
+
+static struct platform_driver cdns_gpio_driver = {
+	.driver = {
+		.name = "cdns-gpio",
+		.of_match_table = cdns_of_ids,
+	},
+	.probe = cdns_gpio_probe,
+	.remove = cdns_gpio_remove,
+};
+module_platform_driver(cdns_gpio_driver);
+
+MODULE_AUTHOR("Jan Kotas <jank@xxxxxxxxxxx>");
+MODULE_DESCRIPTION("Cadence GPIO driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:cdns-gpio");
-- 
2.15.0