gpio MIPS/OCTEON: Add a driver for OCTEON's on-chip GPIO pins.

The SOCs in the OCTEON family have 16 (or in some cases 20) on-chip
GPIO pins, this driver handles them all.  Configuring the pins as
interrupt sources is handled elsewhere (OCTEON's irq handling code).

Signed-off-by: David Daney <david.daney@cavium.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-gpio@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/5633/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

drivers/gpio/Kconfig

@@ -193,6 +193,14 @@ config GPIO_MXS
 	select GPIO_GENERIC
 	select GENERIC_IRQ_CHIP
 
+config GPIO_OCTEON
+	tristate "Cavium OCTEON GPIO"
+	depends on GPIOLIB && CAVIUM_OCTEON_SOC
+	default y
+	help
+	  Say yes here to support the on-chip GPIO lines on the OCTEON
+	  family of SOCs.
+
 config GPIO_PL061
 	bool "PrimeCell PL061 GPIO support"
 	depends on ARM && ARM_AMBA

drivers/gpio/Makefile

@@ -50,6 +50,7 @@ obj-$(CONFIG_GPIO_MSM_V2)	+= gpio-msm-v2.o
 obj-$(CONFIG_GPIO_MVEBU)        += gpio-mvebu.o
 obj-$(CONFIG_GPIO_MXC)		+= gpio-mxc.o
 obj-$(CONFIG_GPIO_MXS)		+= gpio-mxs.o
+obj-$(CONFIG_GPIO_OCTEON)	+= gpio-octeon.o
 obj-$(CONFIG_ARCH_OMAP)		+= gpio-omap.o
 obj-$(CONFIG_GPIO_PCA953X)	+= gpio-pca953x.o
 obj-$(CONFIG_GPIO_PCF857X)	+= gpio-pcf857x.o

drivers/gpio/gpio-octeon.c

@@ -0,0 +1,157 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2011, 2012 Cavium Inc.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/gpio.h>
+#include <linux/io.h>
+
+#include <asm/octeon/octeon.h>
+#include <asm/octeon/cvmx-gpio-defs.h>
+
+#define RX_DAT 0x80
+#define TX_SET 0x88
+#define TX_CLEAR 0x90
+/*
+ * The address offset of the GPIO configuration register for a given
+ * line.
+ */
+static unsigned int bit_cfg_reg(unsigned int offset)
+{
+	/*
+	 * The register stride is 8, with a discontinuity after the
+	 * first 16.
+	 */
+	if (offset < 16)
+		return 8 * offset;
+	else
+		return 8 * (offset - 16) + 0x100;
+}
+
+struct octeon_gpio {
+	struct gpio_chip chip;
+	u64 register_base;
+};
+
+static int octeon_gpio_dir_in(struct gpio_chip *chip, unsigned offset)
+{
+	struct octeon_gpio *gpio = container_of(chip, struct octeon_gpio, chip);
+
+	cvmx_write_csr(gpio->register_base + bit_cfg_reg(offset), 0);
+	return 0;
+}
+
+static void octeon_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct octeon_gpio *gpio = container_of(chip, struct octeon_gpio, chip);
+	u64 mask = 1ull << offset;
+	u64 reg = gpio->register_base + (value ? TX_SET : TX_CLEAR);
+	cvmx_write_csr(reg, mask);
+}
+
+static int octeon_gpio_dir_out(struct gpio_chip *chip, unsigned offset,
+			       int value)
+{
+	struct octeon_gpio *gpio = container_of(chip, struct octeon_gpio, chip);
+	union cvmx_gpio_bit_cfgx cfgx;
+
+	octeon_gpio_set(chip, offset, value);
+
+	cfgx.u64 = 0;
+	cfgx.s.tx_oe = 1;
+
+	cvmx_write_csr(gpio->register_base + bit_cfg_reg(offset), cfgx.u64);
+	return 0;
+}
+
+static int octeon_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+	struct octeon_gpio *gpio = container_of(chip, struct octeon_gpio, chip);
+	u64 read_bits = cvmx_read_csr(gpio->register_base + RX_DAT);
+
+	return ((1ull << offset) & read_bits) != 0;
+}
+
+static int octeon_gpio_probe(struct platform_device *pdev)
+{
+	struct octeon_gpio *gpio;
+	struct gpio_chip *chip;
+	struct resource *res_mem;
+	int err = 0;
+
+	gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
+	if (!gpio)
+		return -ENOMEM;
+	chip = &gpio->chip;
+
+	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (res_mem == NULL) {
+		dev_err(&pdev->dev, "found no memory resource\n");
+		err = -ENXIO;
+		goto out;
+	}
+	if (!devm_request_mem_region(&pdev->dev, res_mem->start,
+					resource_size(res_mem),
+				     res_mem->name)) {
+		dev_err(&pdev->dev, "request_mem_region failed\n");
+		err = -ENXIO;
+		goto out;
+	}
+	gpio->register_base = (u64)devm_ioremap(&pdev->dev, res_mem->start,
+						resource_size(res_mem));
+
+	pdev->dev.platform_data = chip;
+	chip->label = "octeon-gpio";
+	chip->dev = &pdev->dev;
+	chip->owner = THIS_MODULE;
+	chip->base = 0;
+	chip->can_sleep = 0;
+	chip->ngpio = 20;
+	chip->direction_input = octeon_gpio_dir_in;
+	chip->get = octeon_gpio_get;
+	chip->direction_output = octeon_gpio_dir_out;
+	chip->set = octeon_gpio_set;
+	err = gpiochip_add(chip);
+	if (err)
+		goto out;
+
+	dev_info(&pdev->dev, "OCTEON GPIO driver probed.\n");
+out:
+	return err;
+}
+
+static int octeon_gpio_remove(struct platform_device *pdev)
+{
+	struct gpio_chip *chip = pdev->dev.platform_data;
+	return gpiochip_remove(chip);
+}
+
+static struct of_device_id octeon_gpio_match[] = {
+	{
+		.compatible = "cavium,octeon-3860-gpio",
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, octeon_gpio_match);
+
+static struct platform_driver octeon_gpio_driver = {
+	.driver = {
+		.name		= "octeon_gpio",
+		.owner		= THIS_MODULE,
+		.of_match_table = octeon_gpio_match,
+	},
+	.probe		= octeon_gpio_probe,
+	.remove		= octeon_gpio_remove,
+};
+
+module_platform_driver(octeon_gpio_driver);
+
+MODULE_DESCRIPTION("Cavium Inc. OCTEON GPIO Driver");
+MODULE_AUTHOR("David Daney");
+MODULE_LICENSE("GPL");