GPIO: add new Xilinx driver for powerpc

This driver supports the Xilinx XPS GPIO IP core which has the typical
GPIO features.

Signed-off-by: Kiran Sutariya <[e-mail]>
Signed-off-by: John Linn <[e-mail]>
Cc: David Brownell <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Cc: Kumar Gala <[e-mail]>
Cc: "Grant Likely" <[e-mail]>
Cc: <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/gpio/Kconfig

···
 
 # put expanders in the right section, in alphabetical order
 
+comment "Memory mapped GPIO expanders:"
+
+config GPIO_XILINX
+	bool "Xilinx GPIO support"
+	depends on PPC_OF
+	help
+	  Say yes here to support the Xilinx FPGA GPIO device
+
 comment "I2C GPIO expanders:"
 
 config GPIO_MAX732X

drivers/gpio/Makefile

···
 obj-$(CONFIG_GPIO_PCA953X)	+= pca953x.o
 obj-$(CONFIG_GPIO_PCF857X)	+= pcf857x.o
 obj-$(CONFIG_GPIO_TWL4030)	+= twl4030-gpio.o
+obj-$(CONFIG_GPIO_XILINX)	+= xilinx_gpio.o
 obj-$(CONFIG_GPIO_BT8XX)	+= bt8xxgpio.o

drivers/gpio/xilinx_gpio.c

···
+/*
+ * Xilinx gpio driver
+ *
+ * Copyright 2008 Xilinx, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+#include <linux/of_gpio.h>
+#include <linux/io.h>
+#include <linux/gpio.h>
+
+/* Register Offset Definitions */
+#define XGPIO_DATA_OFFSET   (0x0)	/* Data register  */
+#define XGPIO_TRI_OFFSET    (0x4)	/* I/O direction register  */
+
+struct xgpio_instance {
+	struct of_mm_gpio_chip mmchip;
+	u32 gpio_state;		/* GPIO state shadow register */
+	u32 gpio_dir;		/* GPIO direction shadow register */
+	spinlock_t gpio_lock;	/* Lock used for synchronization */
+};
+
+/**
+ * xgpio_get - Read the specified signal of the GPIO device.
+ * @gc:     Pointer to gpio_chip device structure.
+ * @gpio:   GPIO signal number.
+ *
+ * This function reads the specified signal of the GPIO device. It returns 0 if
+ * the signal clear, 1 if signal is set or negative value on error.
+ */
+static int xgpio_get(struct gpio_chip *gc, unsigned int gpio)
+{
+	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
+
+	return (in_be32(mm_gc->regs + XGPIO_DATA_OFFSET) >> gpio) & 1;
+}
+
+/**
+ * xgpio_set - Write the specified signal of the GPIO device.
+ * @gc:     Pointer to gpio_chip device structure.
+ * @gpio:   GPIO signal number.
+ * @val:    Value to be written to specified signal.
+ *
+ * This function writes the specified value in to the specified signal of the
+ * GPIO device.
+ */
+static void xgpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
+{
+	unsigned long flags;
+	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
+	struct xgpio_instance *chip =
+	    container_of(mm_gc, struct xgpio_instance, mmchip);
+
+	spin_lock_irqsave(&chip->gpio_lock, flags);
+
+	/* Write to GPIO signal and set its direction to output */
+	if (val)
+		chip->gpio_state |= 1 << gpio;
+	else
+		chip->gpio_state &= ~(1 << gpio);
+	out_be32(mm_gc->regs + XGPIO_DATA_OFFSET, chip->gpio_state);
+
+	spin_unlock_irqrestore(&chip->gpio_lock, flags);
+}
+
+/**
+ * xgpio_dir_in - Set the direction of the specified GPIO signal as input.
+ * @gc:     Pointer to gpio_chip device structure.
+ * @gpio:   GPIO signal number.
+ *
+ * This function sets the direction of specified GPIO signal as input.
+ * It returns 0 if direction of GPIO signals is set as input otherwise it
+ * returns negative error value.
+ */
+static int xgpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
+{
+	unsigned long flags;
+	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
+	struct xgpio_instance *chip =
+	    container_of(mm_gc, struct xgpio_instance, mmchip);
+
+	spin_lock_irqsave(&chip->gpio_lock, flags);
+
+	/* Set the GPIO bit in shadow register and set direction as input */
+	chip->gpio_dir |= (1 << gpio);
+	out_be32(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir);
+
+	spin_unlock_irqrestore(&chip->gpio_lock, flags);
+
+	return 0;
+}
+
+/**
+ * xgpio_dir_out - Set the direction of the specified GPIO signal as output.
+ * @gc:     Pointer to gpio_chip device structure.
+ * @gpio:   GPIO signal number.
+ * @val:    Value to be written to specified signal.
+ *
+ * This function sets the direction of specified GPIO signal as output. If all
+ * GPIO signals of GPIO chip is configured as input then it returns
+ * error otherwise it returns 0.
+ */
+static int xgpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
+{
+	unsigned long flags;
+	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
+	struct xgpio_instance *chip =
+	    container_of(mm_gc, struct xgpio_instance, mmchip);
+
+	spin_lock_irqsave(&chip->gpio_lock, flags);
+
+	/* Write state of GPIO signal */
+	if (val)
+		chip->gpio_state |= 1 << gpio;
+	else
+		chip->gpio_state &= ~(1 << gpio);
+	out_be32(mm_gc->regs + XGPIO_DATA_OFFSET, chip->gpio_state);
+
+	/* Clear the GPIO bit in shadow register and set direction as output */
+	chip->gpio_dir &= (~(1 << gpio));
+	out_be32(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir);
+
+	spin_unlock_irqrestore(&chip->gpio_lock, flags);
+
+	return 0;
+}
+
+/**
+ * xgpio_save_regs - Set initial values of GPIO pins
+ * @mm_gc: pointer to memory mapped GPIO chip structure
+ */
+static void xgpio_save_regs(struct of_mm_gpio_chip *mm_gc)
+{
+	struct xgpio_instance *chip =
+	    container_of(mm_gc, struct xgpio_instance, mmchip);
+
+	out_be32(mm_gc->regs + XGPIO_DATA_OFFSET, chip->gpio_state);
+	out_be32(mm_gc->regs + XGPIO_TRI_OFFSET, chip->gpio_dir);
+}
+
+/**
+ * xgpio_of_probe - Probe method for the GPIO device.
+ * @np: pointer to device tree node
+ *
+ * This function probes the GPIO device in the device tree. It initializes the
+ * driver data structure. It returns 0, if the driver is bound to the GPIO
+ * device, or a negative value if there is an error.
+ */
+static int __devinit xgpio_of_probe(struct device_node *np)
+{
+	struct xgpio_instance *chip;
+	struct of_gpio_chip *ofchip;
+	int status = 0;
+	const u32 *tree_info;
+
+	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+	ofchip = &chip->mmchip.of_gc;
+
+	/* Update GPIO state shadow register with default value */
+	tree_info = of_get_property(np, "xlnx,dout-default", NULL);
+	if (tree_info)
+		chip->gpio_state = *tree_info;
+
+	/* Update GPIO direction shadow register with default value */
+	chip->gpio_dir = 0xFFFFFFFF; /* By default, all pins are inputs */
+	tree_info = of_get_property(np, "xlnx,tri-default", NULL);
+	if (tree_info)
+		chip->gpio_dir = *tree_info;
+
+	/* Check device node and parent device node for device width */
+	ofchip->gc.ngpio = 32; /* By default assume full GPIO controller */
+	tree_info = of_get_property(np, "xlnx,gpio-width", NULL);
+	if (!tree_info)
+		tree_info = of_get_property(np->parent,
+					    "xlnx,gpio-width", NULL);
+	if (tree_info)
+		ofchip->gc.ngpio = *tree_info;
+
+	spin_lock_init(&chip->gpio_lock);
+
+	ofchip->gpio_cells = 2;
+	ofchip->gc.direction_input = xgpio_dir_in;
+	ofchip->gc.direction_output = xgpio_dir_out;
+	ofchip->gc.get = xgpio_get;
+	ofchip->gc.set = xgpio_set;
+
+	chip->mmchip.save_regs = xgpio_save_regs;
+
+	/* Call the OF gpio helper to setup and register the GPIO device */
+	status = of_mm_gpiochip_add(np, &chip->mmchip);
+	if (status) {
+		kfree(chip);
+		pr_err("%s: error in probe function with status %d\n",
+		       np->full_name, status);
+		return status;
+	}
+	pr_info("XGpio: %s: registered\n", np->full_name);
+	return 0;
+}
+
+static struct of_device_id xgpio_of_match[] __devinitdata = {
+	{ .compatible = "xlnx,xps-gpio-1.00.a", },
+	{ /* end of list */ },
+};
+
+static int __init xgpio_init(void)
+{
+	struct device_node *np;
+
+	for_each_matching_node(np, xgpio_of_match)
+		xgpio_of_probe(np);
+
+	return 0;
+}
+
+/* Make sure we get initialized before anyone else tries to use us */
+subsys_initcall(xgpio_init);
+/* No exit call at the moment as we cannot unregister of GPIO chips */
+
+MODULE_AUTHOR("Xilinx, Inc.");
+MODULE_DESCRIPTION("Xilinx GPIO driver");
+MODULE_LICENSE("GPL");