Re: + gpio-add-new-altera-pio-driver.patch added to -mm tree

Re: + gpio-add-new-altera-pio-driver.patch added to -mm tree

[Thomas Chou]

Dear Andrew,

On 01/27/2011 06:37 AM, akpm@linux-foundation.org wrote:
> The patch titled
>       gpio: add new Altera PIO driver
> has been added to the -mm tree.  Its filename is
>       gpio-add-new-altera-pio-driver.patch
>
> Before you just go and hit "reply", please:
>     a) Consider who else should be cc'ed
>     b) Prefer to cc a suitable mailing list as well
>     c) Ideally: find the original patch on the mailing list and do a
>        reply-to-all to that, adding suitable additional cc's
>
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
>
> See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
> out what to do about this
>
> The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
>
> ------------------------------------------------------
> Subject: gpio: add new Altera PIO driver
> From: Thomas Chou<thomas@wytron.com.tw>
>
> This driver supports the Altera PIO core.
>
> Signed-off-by: Thomas Chou<thomas@wytron.com.tw>
> Signed-off-by: Andrew Morton<akpm@linux-foundation.org>

Please kindly merge it into Linus's tree.

Best regards,
Thomas

> ---
>
>   drivers/gpio/Kconfig       |    6
>   drivers/gpio/Makefile      |    1
>   drivers/gpio/altera_gpio.c |  233 +++++++++++++++++++++++++++++++++++
>   3 files changed, 240 insertions(+)
>
> diff -puN drivers/gpio/Kconfig~gpio-add-new-altera-pio-driver drivers/gpio/Kconfig
> --- a/drivers/gpio/Kconfig~gpio-add-new-altera-pio-driver
> +++ a/drivers/gpio/Kconfig
> @@ -70,6 +70,12 @@ config GPIO_MAX730X
>
>   comment "Memory mapped GPIO expanders:"
>
> +config GPIO_ALTERA
> +	bool "Altera GPIO"
> +	depends on OF
> +	help
> +	  Say yes here to support the Altera PIO device
> +
>   config GPIO_BASIC_MMIO
>   	tristate "Basic memory-mapped GPIO controllers support"
>   	help
> diff -puN drivers/gpio/Makefile~gpio-add-new-altera-pio-driver drivers/gpio/Makefile
> --- a/drivers/gpio/Makefile~gpio-add-new-altera-pio-driver
> +++ a/drivers/gpio/Makefile
> @@ -8,6 +8,7 @@ ccflags-$(CONFIG_DEBUG_GPIO)	+= -DDEBUG
>
>   obj-$(CONFIG_GPIOLIB)		+= gpiolib.o
>
> +obj-$(CONFIG_GPIO_ALTERA)	+= altera_gpio.o
>   obj-$(CONFIG_GPIO_ADP5520)	+= adp5520-gpio.o
>   obj-$(CONFIG_GPIO_ADP5588)	+= adp5588-gpio.o
>   obj-$(CONFIG_GPIO_BASIC_MMIO)	+= basic_mmio_gpio.o
> diff -puN /dev/null drivers/gpio/altera_gpio.c
> --- /dev/null
> +++ a/drivers/gpio/altera_gpio.c
> @@ -0,0 +1,233 @@
> +/*
> + * Altera GPIO driver
> + *
> + * Copyright (C) 2011 Thomas Chou<thomas@wytron.com.tw>
> + *
> + * Based on Xilinx gpio driver, which is
> + * 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>
> +#include<linux/slab.h>
> +
> +#define DRV_NAME "altera_gpio"
> +
> +/* Register Offset Definitions */
> +#define ALTERA_GPIO_DATA_OFFSET   0x0	/* Data register  */
> +#define ALTERA_GPIO_DIR_OFFSET    0x4	/* I/O direction register  */
> +
> +struct altera_gpio_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 */
> +};
> +
> +/*
> + * altera_gpio_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 altera_gpio_get(struct gpio_chip *gc, unsigned int gpio)
> +{
> +	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
> +
> +	return (readl(mm_gc->regs + ALTERA_GPIO_DATA_OFFSET)>>  gpio)&  1;
> +}
> +
> +/*
> + * altera_gpio_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 altera_gpio_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 altera_gpio_instance *chip =
> +	    container_of(mm_gc, struct altera_gpio_instance, mmchip);
> +
> +	spin_lock_irqsave(&chip->gpio_lock, flags);
> +
> +	/* Write to shadow register and output */
> +	if (val)
> +		chip->gpio_state |= 1<<  gpio;
> +	else
> +		chip->gpio_state&= ~(1<<  gpio);
> +	writel(chip->gpio_state, mm_gc->regs + ALTERA_GPIO_DATA_OFFSET);
> +
> +	spin_unlock_irqrestore(&chip->gpio_lock, flags);
> +}
> +
> +/*
> + * altera_gpio_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 altera_gpio_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 altera_gpio_instance *chip =
> +	    container_of(mm_gc, struct altera_gpio_instance, mmchip);
> +
> +	spin_lock_irqsave(&chip->gpio_lock, flags);
> +
> +	/* Clear the GPIO bit in shadow register and set direction as input */
> +	chip->gpio_dir&= ~(1<<  gpio);
> +	writel(chip->gpio_dir, mm_gc->regs + ALTERA_GPIO_DIR_OFFSET);
> +
> +	spin_unlock_irqrestore(&chip->gpio_lock, flags);
> +
> +	return 0;
> +}
> +
> +/*
> + * altera_gpio_dir_out - Set the direction of the specified GPIO 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 altera_gpio_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 altera_gpio_instance *chip =
> +	    container_of(mm_gc, struct altera_gpio_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);
> +	writel(chip->gpio_state, mm_gc->regs + ALTERA_GPIO_DATA_OFFSET);
> +
> +	/* Set the GPIO bit in shadow register and set direction as output */
> +	chip->gpio_dir |= (1<<  gpio);
> +	writel(chip->gpio_dir, mm_gc->regs + ALTERA_GPIO_DIR_OFFSET);
> +
> +	spin_unlock_irqrestore(&chip->gpio_lock, flags);
> +
> +	return 0;
> +}
> +
> +/*
> + * altera_gpio_save_regs - Set initial values of GPIO pins
> + * @mm_gc: pointer to memory mapped GPIO chip structure
> + */
> +static void altera_gpio_save_regs(struct of_mm_gpio_chip *mm_gc)
> +{
> +	struct altera_gpio_instance *chip =
> +	    container_of(mm_gc, struct altera_gpio_instance, mmchip);
> +
> +	writel(chip->gpio_state, mm_gc->regs + ALTERA_GPIO_DATA_OFFSET);
> +	writel(chip->gpio_dir, mm_gc->regs + ALTERA_GPIO_DIR_OFFSET);
> +}
> +
> +/*
> + * altera_gpio_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 altera_gpio_of_probe(struct device_node *np)
> +{
> +	struct altera_gpio_instance *chip;
> +	int status = 0;
> +	const u32 *tree_info;
> +
> +	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
> +	if (!chip)
> +		return -ENOMEM;
> +
> +	/* Update GPIO state shadow register with default value */
> +	tree_info = of_get_property(np, "resetvalue", NULL);
> +	if (tree_info)
> +		chip->gpio_state = be32_to_cpup(tree_info);
> +
> +	/* Update GPIO direction shadow register with default value */
> +	chip->gpio_dir = 0; /* By default, all pins are inputs */
> +
> +	/* Check device node for device width */
> +	chip->mmchip.gc.ngpio = 32; /* By default assume full GPIO controller */
> +	tree_info = of_get_property(np, "width", NULL);
> +	if (tree_info)
> +		chip->mmchip.gc.ngpio = be32_to_cpup(tree_info);
> +
> +	spin_lock_init(&chip->gpio_lock);
> +
> +	chip->mmchip.gc.direction_input = altera_gpio_dir_in;
> +	chip->mmchip.gc.direction_output = altera_gpio_dir_out;
> +	chip->mmchip.gc.get = altera_gpio_get;
> +	chip->mmchip.gc.set = altera_gpio_set;
> +
> +	chip->mmchip.save_regs = altera_gpio_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(DRV_NAME ": %s: registered\n", np->full_name);
> +	return 0;
> +}
> +
> +static struct of_device_id altera_gpio_of_match[] __devinitdata = {
> +	{ .compatible = "altr,pio-1.0", },
> +	{},
> +};
> +
> +static int __init altera_gpio_init(void)
> +{
> +	struct device_node *np;
> +
> +	for_each_matching_node(np, altera_gpio_of_match)
> +		altera_gpio_of_probe(np);
> +
> +	return 0;
> +}
> +
> +/* Make sure we get initialized before anyone else tries to use us */
> +subsys_initcall(altera_gpio_init);
> +/* No exit call at the moment as we cannot unregister of GPIO chips */
> +
> +MODULE_DESCRIPTION("Altera GPIO driver");
> +MODULE_AUTHOR("Thomas Chou<thomas@wytron.com.tw>");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:" DRV_NAME);
> _
>
> Patches currently in -mm which might be from thomas@wytron.com.tw are
>
> gpio-add-new-altera-pio-driver.patch
>
>

[PATCH v2] gpio: add new Altera PIO driver

[Thomas Chou]

This driver supports the Altera PIO core.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
---
v2 change compatible vendor to uppercase, ALTR.
   add dts binding doc.

 .../devicetree/bindings/gpio/altera_gpio.txt       |    7 +
 drivers/gpio/Kconfig                               |    6 +
 drivers/gpio/Makefile                              |    1 +
 drivers/gpio/altera_gpio.c                         |  233 ++++++++++++++++++++
 4 files changed, 247 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/gpio/altera_gpio.txt
 create mode 100644 drivers/gpio/altera_gpio.c

diff --git a/Documentation/devicetree/bindings/gpio/altera_gpio.txt b/Documentation/devicetree/bindings/gpio/altera_gpio.txt
new file mode 100644
index 0000000..5ab751a
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/altera_gpio.txt
@@ -0,0 +1,7 @@
+Altera GPIO
+
+Required properties:
+- compatible : should be "ALTR,pio-1.0".
+Optional properties:
+- resetvalue : the reset value of the output port.
+- width : the width of the port in number of bits.
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 664660e..40271f0 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -70,6 +70,12 @@ config GPIO_MAX730X
 
 comment "Memory mapped GPIO expanders:"
 
+config GPIO_ALTERA
+	bool "Altera GPIO"
+	depends on OF
+	help
+	  Say yes here to support the Altera PIO device
+
 config GPIO_BASIC_MMIO
 	tristate "Basic memory-mapped GPIO controllers support"
 	help
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 3351cf8..ed11932 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -8,6 +8,7 @@ ccflags-$(CONFIG_DEBUG_GPIO)	+= -DDEBUG
 
 obj-$(CONFIG_GPIOLIB)		+= gpiolib.o
 
+obj-$(CONFIG_GPIO_ALTERA)	+= altera_gpio.o
 obj-$(CONFIG_GPIO_ADP5520)	+= adp5520-gpio.o
 obj-$(CONFIG_GPIO_ADP5588)	+= adp5588-gpio.o
 obj-$(CONFIG_GPIO_BASIC_MMIO)	+= basic_mmio_gpio.o
diff --git a/drivers/gpio/altera_gpio.c b/drivers/gpio/altera_gpio.c
new file mode 100644
index 0000000..a173eb3
--- /dev/null
+++ b/drivers/gpio/altera_gpio.c
@@ -0,0 +1,233 @@
+/*
+ * Altera GPIO driver
+ *
+ * Copyright (C) 2011 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * Based on Xilinx gpio driver, which is
+ * 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>
+#include <linux/slab.h>
+
+#define DRV_NAME "altera_gpio"
+
+/* Register Offset Definitions */
+#define ALTERA_GPIO_DATA_OFFSET   0x0	/* Data register  */
+#define ALTERA_GPIO_DIR_OFFSET    0x4	/* I/O direction register  */
+
+struct altera_gpio_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 */
+};
+
+/*
+ * altera_gpio_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 altera_gpio_get(struct gpio_chip *gc, unsigned int gpio)
+{
+	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
+
+	return (readl(mm_gc->regs + ALTERA_GPIO_DATA_OFFSET) >> gpio) & 1;
+}
+
+/*
+ * altera_gpio_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 altera_gpio_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 altera_gpio_instance *chip =
+	    container_of(mm_gc, struct altera_gpio_instance, mmchip);
+
+	spin_lock_irqsave(&chip->gpio_lock, flags);
+
+	/* Write to shadow register and output */
+	if (val)
+		chip->gpio_state |= 1 << gpio;
+	else
+		chip->gpio_state &= ~(1 << gpio);
+	writel(chip->gpio_state, mm_gc->regs + ALTERA_GPIO_DATA_OFFSET);
+
+	spin_unlock_irqrestore(&chip->gpio_lock, flags);
+}
+
+/*
+ * altera_gpio_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 altera_gpio_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 altera_gpio_instance *chip =
+	    container_of(mm_gc, struct altera_gpio_instance, mmchip);
+
+	spin_lock_irqsave(&chip->gpio_lock, flags);
+
+	/* Clear the GPIO bit in shadow register and set direction as input */
+	chip->gpio_dir &= ~(1 << gpio);
+	writel(chip->gpio_dir, mm_gc->regs + ALTERA_GPIO_DIR_OFFSET);
+
+	spin_unlock_irqrestore(&chip->gpio_lock, flags);
+
+	return 0;
+}
+
+/*
+ * altera_gpio_dir_out - Set the direction of the specified GPIO 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 altera_gpio_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 altera_gpio_instance *chip =
+	    container_of(mm_gc, struct altera_gpio_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);
+	writel(chip->gpio_state, mm_gc->regs + ALTERA_GPIO_DATA_OFFSET);
+
+	/* Set the GPIO bit in shadow register and set direction as output */
+	chip->gpio_dir |= (1 << gpio);
+	writel(chip->gpio_dir, mm_gc->regs + ALTERA_GPIO_DIR_OFFSET);
+
+	spin_unlock_irqrestore(&chip->gpio_lock, flags);
+
+	return 0;
+}
+
+/*
+ * altera_gpio_save_regs - Set initial values of GPIO pins
+ * @mm_gc: pointer to memory mapped GPIO chip structure
+ */
+static void altera_gpio_save_regs(struct of_mm_gpio_chip *mm_gc)
+{
+	struct altera_gpio_instance *chip =
+	    container_of(mm_gc, struct altera_gpio_instance, mmchip);
+
+	writel(chip->gpio_state, mm_gc->regs + ALTERA_GPIO_DATA_OFFSET);
+	writel(chip->gpio_dir, mm_gc->regs + ALTERA_GPIO_DIR_OFFSET);
+}
+
+/*
+ * altera_gpio_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 altera_gpio_of_probe(struct device_node *np)
+{
+	struct altera_gpio_instance *chip;
+	int status = 0;
+	const u32 *tree_info;
+
+	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	/* Update GPIO state shadow register with default value */
+	tree_info = of_get_property(np, "resetvalue", NULL);
+	if (tree_info)
+		chip->gpio_state = be32_to_cpup(tree_info);
+
+	/* Update GPIO direction shadow register with default value */
+	chip->gpio_dir = 0; /* By default, all pins are inputs */
+
+	/* Check device node for device width */
+	chip->mmchip.gc.ngpio = 32; /* By default assume full GPIO controller */
+	tree_info = of_get_property(np, "width", NULL);
+	if (tree_info)
+		chip->mmchip.gc.ngpio = be32_to_cpup(tree_info);
+
+	spin_lock_init(&chip->gpio_lock);
+
+	chip->mmchip.gc.direction_input = altera_gpio_dir_in;
+	chip->mmchip.gc.direction_output = altera_gpio_dir_out;
+	chip->mmchip.gc.get = altera_gpio_get;
+	chip->mmchip.gc.set = altera_gpio_set;
+
+	chip->mmchip.save_regs = altera_gpio_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(DRV_NAME ": %s: registered\n", np->full_name);
+	return 0;
+}
+
+static struct of_device_id altera_gpio_of_match[] __devinitdata = {
+	{ .compatible = "ALTR,pio-1.0", },
+	{},
+};
+
+static int __init altera_gpio_init(void)
+{
+	struct device_node *np;
+
+	for_each_matching_node(np, altera_gpio_of_match)
+		altera_gpio_of_probe(np);
+
+	return 0;
+}
+
+/* Make sure we get initialized before anyone else tries to use us */
+subsys_initcall(altera_gpio_init);
+/* No exit call at the moment as we cannot unregister of GPIO chips */
+
+MODULE_DESCRIPTION("Altera GPIO driver");
+MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRV_NAME);
-- 
1.7.3.5

Re: [PATCH v2] gpio: add new Altera PIO driver

[Grant Likely]

On Thu, Feb 03, 2011 at 03:56:57PM +0800, Thomas Chou wrote:
> This driver supports the Altera PIO core.
> 
> Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
> ---
> v2 change compatible vendor to uppercase, ALTR.
>    add dts binding doc.
> 
>  .../devicetree/bindings/gpio/altera_gpio.txt       |    7 +
>  drivers/gpio/Kconfig                               |    6 +
>  drivers/gpio/Makefile                              |    1 +
>  drivers/gpio/altera_gpio.c                         |  233 ++++++++++++++++++++
>  4 files changed, 247 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/gpio/altera_gpio.txt
>  create mode 100644 drivers/gpio/altera_gpio.c
> 
> diff --git a/Documentation/devicetree/bindings/gpio/altera_gpio.txt b/Documentation/devicetree/bindings/gpio/altera_gpio.txt
> new file mode 100644
> index 0000000..5ab751a
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/gpio/altera_gpio.txt
> @@ -0,0 +1,7 @@
> +Altera GPIO
> +
> +Required properties:
> +- compatible : should be "ALTR,pio-1.0".
> +Optional properties:
> +- resetvalue : the reset value of the output port.
> +- width : the width of the port in number of bits.
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 664660e..40271f0 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -70,6 +70,12 @@ config GPIO_MAX730X
>  
>  comment "Memory mapped GPIO expanders:"
>  
> +config GPIO_ALTERA
> +	bool "Altera GPIO"
> +	depends on OF
> +	help
> +	  Say yes here to support the Altera PIO device
> +
>  config GPIO_BASIC_MMIO
>  	tristate "Basic memory-mapped GPIO controllers support"
>  	help
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 3351cf8..ed11932 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -8,6 +8,7 @@ ccflags-$(CONFIG_DEBUG_GPIO)	+= -DDEBUG
>  
>  obj-$(CONFIG_GPIOLIB)		+= gpiolib.o
>  
> +obj-$(CONFIG_GPIO_ALTERA)	+= altera_gpio.o

This list is mostly alphabetized.  Please move down 2 lines below the
ADP5588 line.

>  obj-$(CONFIG_GPIO_ADP5520)	+= adp5520-gpio.o
>  obj-$(CONFIG_GPIO_ADP5588)	+= adp5588-gpio.o
>  obj-$(CONFIG_GPIO_BASIC_MMIO)	+= basic_mmio_gpio.o
> diff --git a/drivers/gpio/altera_gpio.c b/drivers/gpio/altera_gpio.c
> new file mode 100644
> index 0000000..a173eb3
> --- /dev/null
> +++ b/drivers/gpio/altera_gpio.c
> @@ -0,0 +1,233 @@
> +/*
> + * Altera GPIO driver
> + *
> + * Copyright (C) 2011 Thomas Chou <thomas@wytron.com.tw>
> + *
> + * Based on Xilinx gpio driver, which is
> + * 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>
> +#include <linux/slab.h>
> +
> +#define DRV_NAME "altera_gpio"
> +
> +/* Register Offset Definitions */
> +#define ALTERA_GPIO_DATA_OFFSET   0x0	/* Data register  */
> +#define ALTERA_GPIO_DIR_OFFSET    0x4	/* I/O direction register  */
> +
> +struct altera_gpio_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 */
> +};
> +
> +/*
> + * altera_gpio_get - Read the specified signal of the GPIO device.

Kerneldoc format is 2 asterisks on the first line of a function
documentation block, like this:

/**
 * altera_gpio_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 altera_gpio_get(struct gpio_chip *gc, unsigned int gpio)
> +{
> +	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
> +
> +	return (readl(mm_gc->regs + ALTERA_GPIO_DATA_OFFSET) >> gpio) & 1;
> +}
> +
> +/*
> + * altera_gpio_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 altera_gpio_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 altera_gpio_instance *chip =
> +	    container_of(mm_gc, struct altera_gpio_instance, mmchip);
> +
> +	spin_lock_irqsave(&chip->gpio_lock, flags);
> +
> +	/* Write to shadow register and output */
> +	if (val)
> +		chip->gpio_state |= 1 << gpio;
> +	else
> +		chip->gpio_state &= ~(1 << gpio);
> +	writel(chip->gpio_state, mm_gc->regs + ALTERA_GPIO_DATA_OFFSET);
> +
> +	spin_unlock_irqrestore(&chip->gpio_lock, flags);
> +}
> +
> +/*
> + * altera_gpio_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 altera_gpio_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 altera_gpio_instance *chip =
> +	    container_of(mm_gc, struct altera_gpio_instance, mmchip);
> +
> +	spin_lock_irqsave(&chip->gpio_lock, flags);
> +
> +	/* Clear the GPIO bit in shadow register and set direction as input */
> +	chip->gpio_dir &= ~(1 << gpio);
> +	writel(chip->gpio_dir, mm_gc->regs + ALTERA_GPIO_DIR_OFFSET);
> +
> +	spin_unlock_irqrestore(&chip->gpio_lock, flags);
> +
> +	return 0;
> +}
> +
> +/*
> + * altera_gpio_dir_out - Set the direction of the specified GPIO 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 altera_gpio_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 altera_gpio_instance *chip =
> +	    container_of(mm_gc, struct altera_gpio_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);
> +	writel(chip->gpio_state, mm_gc->regs + ALTERA_GPIO_DATA_OFFSET);
> +
> +	/* Set the GPIO bit in shadow register and set direction as output */
> +	chip->gpio_dir |= (1 << gpio);
> +	writel(chip->gpio_dir, mm_gc->regs + ALTERA_GPIO_DIR_OFFSET);
> +
> +	spin_unlock_irqrestore(&chip->gpio_lock, flags);
> +
> +	return 0;
> +}
> +
> +/*
> + * altera_gpio_save_regs - Set initial values of GPIO pins
> + * @mm_gc: pointer to memory mapped GPIO chip structure
> + */
> +static void altera_gpio_save_regs(struct of_mm_gpio_chip *mm_gc)
> +{
> +	struct altera_gpio_instance *chip =
> +	    container_of(mm_gc, struct altera_gpio_instance, mmchip);

This container_of is used several times.  It would be worth creating a
to_altera_gpio() macro.

> +
> +	writel(chip->gpio_state, mm_gc->regs + ALTERA_GPIO_DATA_OFFSET);
> +	writel(chip->gpio_dir, mm_gc->regs + ALTERA_GPIO_DIR_OFFSET);
> +}
> +
> +/*
> + * altera_gpio_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 altera_gpio_of_probe(struct device_node *np)
> +{
> +	struct altera_gpio_instance *chip;
> +	int status = 0;
> +	const u32 *tree_info;

const __be32 *tree_info;

> +
> +	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
> +	if (!chip)
> +		return -ENOMEM;
> +
> +	/* Update GPIO state shadow register with default value */
> +	tree_info = of_get_property(np, "resetvalue", NULL);
> +	if (tree_info)
> +		chip->gpio_state = be32_to_cpup(tree_info);

This would be better:
	tree_info = of_get_property(np, "resetvalue", &len);
	if (tree_info & len >= sizeof(u32))
		chip->gpio_state = be32_to_cpup(tree_info);

> +
> +	/* Update GPIO direction shadow register with default value */
> +	chip->gpio_dir = 0; /* By default, all pins are inputs */
> +
> +	/* Check device node for device width */
> +	chip->mmchip.gc.ngpio = 32; /* By default assume full GPIO controller */
> +	tree_info = of_get_property(np, "width", NULL);
> +	if (tree_info)
> +		chip->mmchip.gc.ngpio = be32_to_cpup(tree_info);
> +
> +	spin_lock_init(&chip->gpio_lock);
> +
> +	chip->mmchip.gc.direction_input = altera_gpio_dir_in;
> +	chip->mmchip.gc.direction_output = altera_gpio_dir_out;
> +	chip->mmchip.gc.get = altera_gpio_get;
> +	chip->mmchip.gc.set = altera_gpio_set;
> +
> +	chip->mmchip.save_regs = altera_gpio_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(DRV_NAME ": %s: registered\n", np->full_name);
> +	return 0;
> +}
> +
> +static struct of_device_id altera_gpio_of_match[] __devinitdata = {
> +	{ .compatible = "ALTR,pio-1.0", },
> +	{},
> +};
> +
> +static int __init altera_gpio_init(void)
> +{
> +	struct device_node *np;
> +
> +	for_each_matching_node(np, altera_gpio_of_match)
> +		altera_gpio_of_probe(np);
> +
> +	return 0;
> +}
> +
> +/* Make sure we get initialized before anyone else tries to use us */
> +subsys_initcall(altera_gpio_init);

Ugh.  I'd *really* rather see this implemented as a platform_driver,
but I understand the dependency requirements that it be done before
anyone tries to use it and there isn't a generic solution for
dependency management yet.

However, calling the subsys_initcall() from inside the driver code and
blindly looking for gpio chips is definitely not a good idea because
it doesn't provide architecture code the opportunity to override the
device registration if it needs to.  The altera_gpio_init() and
subsys_initcall() functions should be omitted from this patch and
instead be explicitly called from the board support code.

Otherwise the driver looks good.

g.

> +/* No exit call at the moment as we cannot unregister of GPIO chips */
> +
> +MODULE_DESCRIPTION("Altera GPIO driver");
> +MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:" DRV_NAME);
> -- 
> 1.7.3.5
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

[PATCH v3] gpio: add new Altera PIO driver

[Thomas Chou]

This driver supports the Altera PIO core.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
---
v2 change compatible vendor to uppercase, ALTR.
   add dts binding doc.
v3 remove subsys_initcall.
   add to_altera_gpio() macro.

 .../devicetree/bindings/gpio/altera_gpio.txt       |    7 +
 drivers/gpio/Kconfig                               |    6 +
 drivers/gpio/Makefile                              |    1 +
 drivers/gpio/altera_gpio.c                         |  231 ++++++++++++++++++++
 4 files changed, 245 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/gpio/altera_gpio.txt
 create mode 100644 drivers/gpio/altera_gpio.c

diff --git a/Documentation/devicetree/bindings/gpio/altera_gpio.txt b/Documentation/devicetree/bindings/gpio/altera_gpio.txt
new file mode 100644
index 0000000..5ab751a
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/altera_gpio.txt
@@ -0,0 +1,7 @@
+Altera GPIO
+
+Required properties:
+- compatible : should be "ALTR,pio-1.0".
+Optional properties:
+- resetvalue : the reset value of the output port.
+- width : the width of the port in number of bits.
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 664660e..40271f0 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -70,6 +70,12 @@ config GPIO_MAX730X
 
 comment "Memory mapped GPIO expanders:"
 
+config GPIO_ALTERA
+	bool "Altera GPIO"
+	depends on OF
+	help
+	  Say yes here to support the Altera PIO device
+
 config GPIO_BASIC_MMIO
 	tristate "Basic memory-mapped GPIO controllers support"
 	help
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 3351cf8..3b7b737 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_GPIOLIB)		+= gpiolib.o
 
 obj-$(CONFIG_GPIO_ADP5520)	+= adp5520-gpio.o
 obj-$(CONFIG_GPIO_ADP5588)	+= adp5588-gpio.o
+obj-$(CONFIG_GPIO_ALTERA)	+= altera_gpio.o
 obj-$(CONFIG_GPIO_BASIC_MMIO)	+= basic_mmio_gpio.o
 obj-$(CONFIG_GPIO_LANGWELL)	+= langwell_gpio.o
 obj-$(CONFIG_GPIO_MAX730X)	+= max730x.o
diff --git a/drivers/gpio/altera_gpio.c b/drivers/gpio/altera_gpio.c
new file mode 100644
index 0000000..ab09f81
--- /dev/null
+++ b/drivers/gpio/altera_gpio.c
@@ -0,0 +1,231 @@
+/*
+ * Altera GPIO driver
+ *
+ * Copyright (C) 2011 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * Based on Xilinx gpio driver, which is
+ * 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>
+#include <linux/slab.h>
+
+#define DRV_NAME "altera_gpio"
+
+/* Register Offset Definitions */
+#define ALTERA_GPIO_DATA_OFFSET   0x0	/* Data register  */
+#define ALTERA_GPIO_DIR_OFFSET    0x4	/* I/O direction register  */
+
+struct altera_gpio_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 */
+};
+
+static inline struct altera_gpio_instance *to_altera_gpio(
+	struct of_mm_gpio_chip *mm_gc)
+{
+	return container_of(mm_gc, struct altera_gpio_instance, mmchip);
+}
+
+/*
+ * altera_gpio_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 altera_gpio_get(struct gpio_chip *gc, unsigned int gpio)
+{
+	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
+
+	return (readl(mm_gc->regs + ALTERA_GPIO_DATA_OFFSET) >> gpio) & 1;
+}
+
+/*
+ * altera_gpio_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 altera_gpio_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 altera_gpio_instance *chip = to_altera_gpio(mm_gc);
+
+	spin_lock_irqsave(&chip->gpio_lock, flags);
+
+	/* Write to shadow register and output */
+	if (val)
+		chip->gpio_state |= 1 << gpio;
+	else
+		chip->gpio_state &= ~(1 << gpio);
+	writel(chip->gpio_state, mm_gc->regs + ALTERA_GPIO_DATA_OFFSET);
+
+	spin_unlock_irqrestore(&chip->gpio_lock, flags);
+}
+
+/*
+ * altera_gpio_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 altera_gpio_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 altera_gpio_instance *chip = to_altera_gpio(mm_gc);
+
+	spin_lock_irqsave(&chip->gpio_lock, flags);
+
+	/* Clear the GPIO bit in shadow register and set direction as input */
+	chip->gpio_dir &= ~(1 << gpio);
+	writel(chip->gpio_dir, mm_gc->regs + ALTERA_GPIO_DIR_OFFSET);
+
+	spin_unlock_irqrestore(&chip->gpio_lock, flags);
+
+	return 0;
+}
+
+/*
+ * altera_gpio_dir_out - Set the direction of the specified GPIO 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 altera_gpio_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 altera_gpio_instance *chip = to_altera_gpio(mm_gc);
+
+	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);
+	writel(chip->gpio_state, mm_gc->regs + ALTERA_GPIO_DATA_OFFSET);
+
+	/* Set the GPIO bit in shadow register and set direction as output */
+	chip->gpio_dir |= (1 << gpio);
+	writel(chip->gpio_dir, mm_gc->regs + ALTERA_GPIO_DIR_OFFSET);
+
+	spin_unlock_irqrestore(&chip->gpio_lock, flags);
+
+	return 0;
+}
+
+/*
+ * altera_gpio_save_regs - Set initial values of GPIO pins
+ * @mm_gc: pointer to memory mapped GPIO chip structure
+ */
+static void altera_gpio_save_regs(struct of_mm_gpio_chip *mm_gc)
+{
+	struct altera_gpio_instance *chip = to_altera_gpio(mm_gc);
+
+	writel(chip->gpio_state, mm_gc->regs + ALTERA_GPIO_DATA_OFFSET);
+	writel(chip->gpio_dir, mm_gc->regs + ALTERA_GPIO_DIR_OFFSET);
+}
+
+/*
+ * altera_gpio_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 altera_gpio_of_probe(struct device_node *np)
+{
+	struct altera_gpio_instance *chip;
+	int status = 0;
+	int len;
+	const __be32 *tree_info;
+
+	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	/* Update GPIO state shadow register with default value */
+	tree_info = of_get_property(np, "resetvalue", &len);
+	if (tree_info && len >= sizeof(__be32))
+		chip->gpio_state = be32_to_cpup(tree_info);
+
+	/* Update GPIO direction shadow register with default value */
+	chip->gpio_dir = 0; /* By default, all pins are inputs */
+
+	/* Check device node for device width */
+	chip->mmchip.gc.ngpio = 32; /* By default assume full GPIO controller */
+	tree_info = of_get_property(np, "width", &len);
+	if (tree_info && len >= sizeof(__be32))
+		chip->mmchip.gc.ngpio = be32_to_cpup(tree_info);
+
+	spin_lock_init(&chip->gpio_lock);
+
+	chip->mmchip.gc.direction_input = altera_gpio_dir_in;
+	chip->mmchip.gc.direction_output = altera_gpio_dir_out;
+	chip->mmchip.gc.get = altera_gpio_get;
+	chip->mmchip.gc.set = altera_gpio_set;
+
+	chip->mmchip.save_regs = altera_gpio_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(DRV_NAME ": %s: registered\n", np->full_name);
+	return 0;
+}
+
+static struct of_device_id altera_gpio_of_match[] __devinitdata = {
+	{ .compatible = "ALTR,pio-1.0", },
+	{},
+};
+
+/* Make sure we get initialized before anyone else tries to use us */
+void __init altera_gpio_init(void)
+{
+	struct device_node *np;
+
+	for_each_matching_node(np, altera_gpio_of_match)
+		altera_gpio_of_probe(np);
+}
+
+MODULE_DESCRIPTION("Altera GPIO driver");
+MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRV_NAME);
-- 
1.7.4