gpio: Loongson1: add Loongson1 GPIO driver

This patch adds GPIO driver for Loongson1B.

Signed-off-by: Kelvin Cheung <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/gpio/Kconfig

···
 	help
 	  Say yes here to support the GPIO device on ZTE ZX SoCs.
 
+config GPIO_LOONGSON1
+	tristate "Loongson1 GPIO support"
+	depends on MACH_LOONGSON32
+	select GPIO_GENERIC
+	help
+	  Say Y or M here to support GPIO on Loongson1 SoCs.
+
 endmenu
 
 menu "Port-mapped I/O GPIO drivers"

drivers/gpio/Makefile

···
 obj-$(CONFIG_GPIO_ZEVIO)	+= gpio-zevio.o
 obj-$(CONFIG_GPIO_ZYNQ)		+= gpio-zynq.o
 obj-$(CONFIG_GPIO_ZX)		+= gpio-zx.o
+obj-$(CONFIG_GPIO_LOONGSON1)	+= gpio-loongson1.o

drivers/gpio/gpio-loongson1.c

···
+/*
+ * GPIO Driver for Loongson 1 SoC
+ *
+ * Copyright (C) 2015-2016 Zhang, Keguang <[e-mail]>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/gpio/driver.h>
+#include <linux/platform_device.h>
+
+/* Loongson 1 GPIO Register Definitions */
+#define GPIO_CFG		0x0
+#define GPIO_DIR		0x10
+#define GPIO_DATA		0x20
+#define GPIO_OUTPUT		0x30
+
+static void __iomem *gpio_reg_base;
+
+static int ls1x_gpio_request(struct gpio_chip *gc, unsigned int offset)
+{
+	unsigned long pinmask = gc->pin2mask(gc, offset);
+	unsigned long flags;
+
+	spin_lock_irqsave(&gc->bgpio_lock, flags);
+	__raw_writel(__raw_readl(gpio_reg_base + GPIO_CFG) | pinmask,
+		     gpio_reg_base + GPIO_CFG);
+	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
+
+	return 0;
+}
+
+static void ls1x_gpio_free(struct gpio_chip *gc, unsigned int offset)
+{
+	unsigned long pinmask = gc->pin2mask(gc, offset);
+	unsigned long flags;
+
+	spin_lock_irqsave(&gc->bgpio_lock, flags);
+	__raw_writel(__raw_readl(gpio_reg_base + GPIO_CFG) & ~pinmask,
+		     gpio_reg_base + GPIO_CFG);
+	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
+}
+
+static int ls1x_gpio_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct gpio_chip *gc;
+	struct resource *res;
+	int ret;
+
+	gc = devm_kzalloc(dev, sizeof(*gc), GFP_KERNEL);
+	if (!gc)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(dev, "failed to get I/O memory\n");
+		return -EINVAL;
+	}
+
+	gpio_reg_base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(gpio_reg_base))
+		return PTR_ERR(gpio_reg_base);
+
+	ret = bgpio_init(gc, dev, 4, gpio_reg_base + GPIO_DATA,
+			 gpio_reg_base + GPIO_OUTPUT, NULL,
+			 NULL, gpio_reg_base + GPIO_DIR, 0);
+	if (ret)
+		goto err;
+
+	gc->owner = THIS_MODULE;
+	gc->request = ls1x_gpio_request;
+	gc->free = ls1x_gpio_free;
+	gc->base = pdev->id * 32;
+
+	ret = devm_gpiochip_add_data(dev, gc, NULL);
+	if (ret)
+		goto err;
+
+	platform_set_drvdata(pdev, gc);
+	dev_info(dev, "Loongson1 GPIO driver registered\n");
+
+	return 0;
+err:
+	dev_err(dev, "failed to register GPIO device\n");
+	return ret;
+}
+
+static struct platform_driver ls1x_gpio_driver = {
+	.probe	= ls1x_gpio_probe,
+	.driver	= {
+		.name	= "ls1x-gpio",
+	},
+};
+
+module_platform_driver(ls1x_gpio_driver);
+
+MODULE_AUTHOR("Kelvin Cheung <[e-mail]>");
+MODULE_DESCRIPTION("Loongson1 GPIO driver");
+MODULE_LICENSE("GPL");