Patchwork PPC440EPx gpio driver

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Submitter Steven A. Falco
Date Oct. 8, 2008, 8:56 p.m.
Message ID <48ED1E96.4060406@harris.com>
Download mbox | patch
Permalink /patch/3377/
State Superseded, archived
Headers show

Comments

Steven A. Falco - Oct. 8, 2008, 8:56 p.m.
I have begun writing a driver for the GPIOs of the PPC440EPx.  I just
noticed that the PIKA Warp .dts references a device "ibm,gpio-440ep",
but so far I have not been able to find a driver for that device.

So, here is what I have so far (patch is off 2.6.27-rc9).  It is not
sufficiently general to be merged at this point, but it does appear
to function with my Sequoia board (only tested gpio input, so far).

Signed-off-by: Steve Falco <sfalco at harris.com>
Anton Vorontsov - Oct. 9, 2008, 1:49 p.m.
Hi Steven,

On Wed, Oct 08, 2008 at 04:56:54PM -0400, Steven A. Falco wrote:
> I have begun writing a driver for the GPIOs of the PPC440EPx.  I just
> noticed that the PIKA Warp .dts references a device "ibm,gpio-440ep",
> but so far I have not been able to find a driver for that device.
> 
> So, here is what I have so far (patch is off 2.6.27-rc9).  It is not
> sufficiently general to be merged at this point, but it does appear
> to function with my Sequoia board (only tested gpio input, so far).

It looks good. Few comments below.

> Signed-off-by: Steve Falco <sfalco at harris.com>
> 
> diff --git a/arch/powerpc/platforms/44x/ppc4xx-gpio.c b/arch/powerpc/platforms/44x/ppc4xx-gpio.c
> new file mode 100644
> index 0000000..ce552b4
> --- /dev/null
> +++ b/arch/powerpc/platforms/44x/ppc4xx-gpio.c
> @@ -0,0 +1,246 @@
> +/*
> + * PPC4xx gpio driver
> + *
> + * Copyright (c) 2008 Harris Corporation
> + * Copyright (c) 2008 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
> + *
> + * 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.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * 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/of.h>
> +#include <linux/kernel.h>
> +#include <linux/of_gpio.h>
> +#include <linux/io.h>
> +#include <linux/of_platform.h>
#include <linux/init.h> (for *_initcall)
#include <linux/compiler.h> (for __iomem)
#include <linux/types.h> (in case you'll use __be32).
#include <linux/spinlock.h>

> +
> +#include <asm/gpio.h>

Please don't include asm/gpio.h directly. There is a new header
to include: linux/gpio.h.

> +#include <asm/ppc4xx.h>
> +
> +static DEFINE_SPINLOCK(gpio_lock);

Why not move this lock into the ppc4xx_gpiochip? Per-bank
locks are better anyway, one bank won't block another.

> +struct ppc4xx_gpiochip {
> +	struct of_mm_gpio_chip mmchip;
> +	unsigned int shadow_or;

I'd suggest to use __be32 types here.

> +	unsigned int shadow_tcr;
> +	unsigned int shadow_osrl;
> +	unsigned int shadow_osrh;
> +	unsigned int shadow_tsrl;
> +	unsigned int shadow_tsrh;
> +	unsigned int shadow_odr;
> +};
> +
> +/*
> + * GPIO LIB API implementation for GPIOs
> + *
> + * There are a maximum of 64 gpios, spread over two sets of control registers.
> + * The sets are called GPIO0 and GPIO1.  Each set is managed separately, so
> + * there will be two entried in the .dts file.
> + */
> +
> +static int ppc4xx_gpio_get(struct gpio_chip *gc, unsigned int gpio)
> +{
> +	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
> +	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
> +	unsigned int ret;

u32 ret; would look better, I think.

> +
> +	ret = (in_be32(&regs->gpio_ir) >> (31 - gpio)) & 1;
> +
> +	return ret;
> +}
> +
> +static inline void
> +__ppc4xx_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
> +{
> +	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
> +	struct ppc4xx_gpiochip *chip = container_of(mm_gc,
> +			struct ppc4xx_gpiochip, mmchip);
> +	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
> +
> +	if (val)
> +		chip->shadow_or |= 1 << (31 - gpio);
> +	else
> +		chip->shadow_or &= ~(1 << (31 - gpio));
> +	out_be32(&regs->gpio_or, chip->shadow_or);
> +}
> +
> +static void
> +ppc4xx_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&gpio_lock, flags);
> +
> +	__ppc4xx_gpio_set(gc, gpio, val);
> +
> +	spin_unlock_irqrestore(&gpio_lock, flags);
> +
> +	pr_debug("%s: gpio: %d val: %d\n", __func__, gpio, val);
> +}
> +
> +static int ppc4xx_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
> +{
> +	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
> +	struct ppc4xx_gpiochip *chip = container_of(mm_gc,
> +			struct ppc4xx_gpiochip, mmchip);
> +	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&gpio_lock, flags);
> +
> +	/* Disable open-drain function */
> +	chip->shadow_odr &= ~(1 << (31 - gpio));
> +	out_be32(&regs->gpio_odr, chip->shadow_odr);
> +
> +	/* Float the pin */
> +	chip->shadow_tcr &= ~(1 << (31 - gpio));
> +	out_be32(&regs->gpio_tcr, chip->shadow_tcr);
> +
> +	/* Bits 0-15 use TSRL/OSRL, bits 16-31 use TSRH/OSRH */
> +	if(gpio < 16) {
> +		chip->shadow_osrl &= ~(3 << ((15 - gpio) * 2));
> +		out_be32(&regs->gpio_osrl, chip->shadow_osrl);
> +
> +		chip->shadow_tsrl &= ~(3 << ((15 - gpio) * 2));
> +		out_be32(&regs->gpio_tsrl, chip->shadow_tsrl);
> +	} else {
> +		chip->shadow_osrh &= ~(3 << ((31 - gpio) * 2));
> +		out_be32(&regs->gpio_osrh, chip->shadow_osrh);
> +
> +		chip->shadow_tsrh &= ~(3 << ((31 - gpio) * 2));
> +		out_be32(&regs->gpio_tsrh, chip->shadow_tsrh);
> +	}
> +
> +	spin_unlock_irqrestore(&gpio_lock, flags);
> +
> +	return 0;
> +}
> +
> +static int
> +ppc4xx_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
> +{
> +	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
> +	struct ppc4xx_gpiochip *chip = container_of(mm_gc,
> +			struct ppc4xx_gpiochip, mmchip);
> +	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&gpio_lock, flags);
> +
> +	/* First set initial value */
> +	__ppc4xx_gpio_set(gc, gpio, val);
> +
> +	/* Disable open-drain function */
> +	chip->shadow_odr &= ~(1 << (31 - gpio));
> +	out_be32(&regs->gpio_odr, chip->shadow_odr);
> +
> +	/* Drive the pin */
> +	chip->shadow_tcr |= (1 << (31 - gpio));
> +	out_be32(&regs->gpio_tcr, chip->shadow_tcr);
> +
> +	/* Bits 0-15 use TSRL, bits 16-31 use TSRH */
> +	if(gpio < 16) {
> +		chip->shadow_osrl &= ~(3 << ((15 - gpio) * 2));
> +		out_be32(&regs->gpio_osrl, chip->shadow_osrl);
> +
> +		chip->shadow_tsrl &= ~(3 << ((15 - gpio) * 2));
> +		out_be32(&regs->gpio_tsrl, chip->shadow_tsrl);
> +	} else {
> +		chip->shadow_osrh &= ~(3 << ((31 - gpio) * 2));
> +		out_be32(&regs->gpio_osrh, chip->shadow_osrh);
> +
> +		chip->shadow_tsrh &= ~(3 << ((31 - gpio) * 2));
> +		out_be32(&regs->gpio_tsrh, chip->shadow_tsrh);
> +	}
> +
> +	spin_unlock_irqrestore(&gpio_lock, flags);
> +
> +	pr_debug("%s: gpio: %d val: %d\n", __func__, gpio, val);
> +
> +	return 0;
> +}
> +
> +static int __devinit ppc4xx_gpiochip_probe(struct of_device *ofdev,
> +					const struct of_device_id *match)
> +{
> +	struct ppc4xx_gpiochip *chip;
> +	struct of_gpio_chip *ofchip;
> +	struct ppc4xx_gpio __iomem *regs;
> +	int ret;
> +
> +	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
> +	if (!chip)
> +		return -ENOMEM;
> +
> +	ofchip = &chip->mmchip.of_gc;
> +
> +	ofchip->gpio_cells          = 2;
> +	ofchip->gc.ngpio            = 32;
> +	ofchip->gc.direction_input  = ppc4xx_gpio_dir_in;
> +	ofchip->gc.direction_output = ppc4xx_gpio_dir_out;
> +	ofchip->gc.get              = ppc4xx_gpio_get;
> +	ofchip->gc.set              = ppc4xx_gpio_set;
> +
> +	ret = of_mm_gpiochip_add(ofdev->node, &chip->mmchip);
> +	if (ret)
> +		return ret;

Leaking the allocated "chip".

> +
> +	regs = chip->mmchip.regs;
> +	chip->shadow_or = in_be32(&regs->gpio_or);

The chip is already added, but you set the shadow values just now.
I mean, this is racy.

There is special .save_regs() callback in the struct of_mm_gpio_chip,
made especially to solve this problem.

> +	chip->shadow_tcr = in_be32(&regs->gpio_tcr);
> +	chip->shadow_osrl = in_be32(&regs->gpio_osrl);
> +	chip->shadow_osrh = in_be32(&regs->gpio_osrh);
> +	chip->shadow_tsrl = in_be32(&regs->gpio_tsrl);
> +	chip->shadow_tsrh = in_be32(&regs->gpio_tsrh);
> +	chip->shadow_odr = in_be32(&regs->gpio_odr);
> +
> +	return 0;
> +}
> +
> +static int ppc4xx_gpiochip_remove(struct of_device *ofdev)
> +{
> +	return -EBUSY;
> +}
> +
> +static const struct of_device_id ppc4xx_gpiochip_match[] = {
> +	{
> +		.compatible = "amcc,ppc4xx-gpio",
> +	},
> +	{}
> +};
> +
> +static struct of_platform_driver ppc4xx_gpiochip_driver = {
> +	.name = "gpio",

The name seems too generic.

> +	.match_table = ppc4xx_gpiochip_match,
> +	.probe = ppc4xx_gpiochip_probe,
> +	.remove = ppc4xx_gpiochip_remove,
> +};
> +
> +static int __init ppc4xx_gpio_init(void)
> +{
> +	if (of_register_platform_driver(&ppc4xx_gpiochip_driver))
> +		printk(KERN_ERR "Unable to register GPIO driver\n");

printk(KERN_ERR "%s: ...", __func__); would make it much clearer which
GPIO driver failed.

> +
> +	return 0;
> +}
> +
> +
> +/* Make sure we get initialised before anyone else tries to use us */
> +subsys_initcall(ppc4xx_gpio_init);

You could get rid of the of_platform_driver and make this
arch_initcall()... I.e. like arch/powerpc/sysdev/qe_lib/gpio.c.

But the driver approach is also OK... I don't have any preference
for this.


Thanks,
Stefan Roese - Oct. 9, 2008, 2:23 p.m.
On Wednesday 08 October 2008, Steven A. Falco wrote:
> I have begun writing a driver for the GPIOs of the PPC440EPx.  I just
> noticed that the PIKA Warp .dts references a device "ibm,gpio-440ep",
> but so far I have not been able to find a driver for that device.
>
> So, here is what I have so far (patch is off 2.6.27-rc9).  It is not
> sufficiently general to be merged at this point, but it does appear
> to function with my Sequoia board (only tested gpio input, so far).

Thanks for this driver.

I have "another" 4xx-gpiolib driver version in my patch queue. It's also not 
polished yet. That's the reason why I didn't post it till now. I'll post my 
driver version in a short while. It's tested on a 405EP and an 440EPx system 
and "should" work on all other 4xx based platforms.

The community then can decide which driver version should be polished for 
upstream merge...

Best regards,
Stefan
Sean MacLennan - Oct. 9, 2008, 10:08 p.m.
On Wed, 08 Oct 2008 16:56:54 -0400
"Steven A. Falco" <sfalco@harris.com> wrote:

>  have begun writing a driver for the GPIOs of the PPC440EPx.  I just
> noticed that the PIKA Warp .dts references a device "ibm,gpio-440ep",
> but so far I have not been able to find a driver for that device.

It's just around the corner, through the blue door ;) That device string
was put in optimistically hoping somebody would write a gpio driver.

FYI the warp has two leds tied to gpios. It currently uses a custom led
driver. Once a gpio driver is written, the of gpio leds driver should
work and the custom driver will go away.

So I am very interested in your driver ;)

Cheers,
   Sean

Patch

diff --git a/arch/powerpc/platforms/44x/ppc4xx-gpio.c b/arch/powerpc/platforms/44x/ppc4xx-gpio.c
new file mode 100644
index 0000000..ce552b4
--- /dev/null
+++ b/arch/powerpc/platforms/44x/ppc4xx-gpio.c
@@ -0,0 +1,246 @@ 
+/*
+ * PPC4xx gpio driver
+ *
+ * Copyright (c) 2008 Harris Corporation
+ * Copyright (c) 2008 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * 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/of.h>
+#include <linux/kernel.h>
+#include <linux/of_gpio.h>
+#include <linux/io.h>
+#include <linux/of_platform.h>
+
+#include <asm/gpio.h>
+#include <asm/ppc4xx.h>
+
+static DEFINE_SPINLOCK(gpio_lock);
+
+struct ppc4xx_gpiochip {
+	struct of_mm_gpio_chip mmchip;
+	unsigned int shadow_or;
+	unsigned int shadow_tcr;
+	unsigned int shadow_osrl;
+	unsigned int shadow_osrh;
+	unsigned int shadow_tsrl;
+	unsigned int shadow_tsrh;
+	unsigned int shadow_odr;
+};
+
+/*
+ * GPIO LIB API implementation for GPIOs
+ *
+ * There are a maximum of 64 gpios, spread over two sets of control registers.
+ * The sets are called GPIO0 and GPIO1.  Each set is managed separately, so
+ * there will be two entried in the .dts file.
+ */
+
+static int ppc4xx_gpio_get(struct gpio_chip *gc, unsigned int gpio)
+{
+	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
+	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
+	unsigned int ret;
+
+	ret = (in_be32(&regs->gpio_ir) >> (31 - gpio)) & 1;
+
+	return ret;
+}
+
+static inline void
+__ppc4xx_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
+{
+	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
+	struct ppc4xx_gpiochip *chip = container_of(mm_gc,
+			struct ppc4xx_gpiochip, mmchip);
+	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
+
+	if (val)
+		chip->shadow_or |= 1 << (31 - gpio);
+	else
+		chip->shadow_or &= ~(1 << (31 - gpio));
+	out_be32(&regs->gpio_or, chip->shadow_or);
+}
+
+static void
+ppc4xx_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	__ppc4xx_gpio_set(gc, gpio, val);
+
+	spin_unlock_irqrestore(&gpio_lock, flags);
+
+	pr_debug("%s: gpio: %d val: %d\n", __func__, gpio, val);
+}
+
+static int ppc4xx_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
+{
+	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
+	struct ppc4xx_gpiochip *chip = container_of(mm_gc,
+			struct ppc4xx_gpiochip, mmchip);
+	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
+	unsigned long flags;
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	/* Disable open-drain function */
+	chip->shadow_odr &= ~(1 << (31 - gpio));
+	out_be32(&regs->gpio_odr, chip->shadow_odr);
+
+	/* Float the pin */
+	chip->shadow_tcr &= ~(1 << (31 - gpio));
+	out_be32(&regs->gpio_tcr, chip->shadow_tcr);
+
+	/* Bits 0-15 use TSRL/OSRL, bits 16-31 use TSRH/OSRH */
+	if(gpio < 16) {
+		chip->shadow_osrl &= ~(3 << ((15 - gpio) * 2));
+		out_be32(&regs->gpio_osrl, chip->shadow_osrl);
+
+		chip->shadow_tsrl &= ~(3 << ((15 - gpio) * 2));
+		out_be32(&regs->gpio_tsrl, chip->shadow_tsrl);
+	} else {
+		chip->shadow_osrh &= ~(3 << ((31 - gpio) * 2));
+		out_be32(&regs->gpio_osrh, chip->shadow_osrh);
+
+		chip->shadow_tsrh &= ~(3 << ((31 - gpio) * 2));
+		out_be32(&regs->gpio_tsrh, chip->shadow_tsrh);
+	}
+
+	spin_unlock_irqrestore(&gpio_lock, flags);
+
+	return 0;
+}
+
+static int
+ppc4xx_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
+{
+	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
+	struct ppc4xx_gpiochip *chip = container_of(mm_gc,
+			struct ppc4xx_gpiochip, mmchip);
+	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
+	unsigned long flags;
+
+	spin_lock_irqsave(&gpio_lock, flags);
+
+	/* First set initial value */
+	__ppc4xx_gpio_set(gc, gpio, val);
+
+	/* Disable open-drain function */
+	chip->shadow_odr &= ~(1 << (31 - gpio));
+	out_be32(&regs->gpio_odr, chip->shadow_odr);
+
+	/* Drive the pin */
+	chip->shadow_tcr |= (1 << (31 - gpio));
+	out_be32(&regs->gpio_tcr, chip->shadow_tcr);
+
+	/* Bits 0-15 use TSRL, bits 16-31 use TSRH */
+	if(gpio < 16) {
+		chip->shadow_osrl &= ~(3 << ((15 - gpio) * 2));
+		out_be32(&regs->gpio_osrl, chip->shadow_osrl);
+
+		chip->shadow_tsrl &= ~(3 << ((15 - gpio) * 2));
+		out_be32(&regs->gpio_tsrl, chip->shadow_tsrl);
+	} else {
+		chip->shadow_osrh &= ~(3 << ((31 - gpio) * 2));
+		out_be32(&regs->gpio_osrh, chip->shadow_osrh);
+
+		chip->shadow_tsrh &= ~(3 << ((31 - gpio) * 2));
+		out_be32(&regs->gpio_tsrh, chip->shadow_tsrh);
+	}
+
+	spin_unlock_irqrestore(&gpio_lock, flags);
+
+	pr_debug("%s: gpio: %d val: %d\n", __func__, gpio, val);
+
+	return 0;
+}
+
+static int __devinit ppc4xx_gpiochip_probe(struct of_device *ofdev,
+					const struct of_device_id *match)
+{
+	struct ppc4xx_gpiochip *chip;
+	struct of_gpio_chip *ofchip;
+	struct ppc4xx_gpio __iomem *regs;
+	int ret;
+
+	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	ofchip = &chip->mmchip.of_gc;
+
+	ofchip->gpio_cells          = 2;
+	ofchip->gc.ngpio            = 32;
+	ofchip->gc.direction_input  = ppc4xx_gpio_dir_in;
+	ofchip->gc.direction_output = ppc4xx_gpio_dir_out;
+	ofchip->gc.get              = ppc4xx_gpio_get;
+	ofchip->gc.set              = ppc4xx_gpio_set;
+
+	ret = of_mm_gpiochip_add(ofdev->node, &chip->mmchip);
+	if (ret)
+		return ret;
+
+	regs = chip->mmchip.regs;
+	chip->shadow_or = in_be32(&regs->gpio_or);
+	chip->shadow_tcr = in_be32(&regs->gpio_tcr);
+	chip->shadow_osrl = in_be32(&regs->gpio_osrl);
+	chip->shadow_osrh = in_be32(&regs->gpio_osrh);
+	chip->shadow_tsrl = in_be32(&regs->gpio_tsrl);
+	chip->shadow_tsrh = in_be32(&regs->gpio_tsrh);
+	chip->shadow_odr = in_be32(&regs->gpio_odr);
+
+	return 0;
+}
+
+static int ppc4xx_gpiochip_remove(struct of_device *ofdev)
+{
+	return -EBUSY;
+}
+
+static const struct of_device_id ppc4xx_gpiochip_match[] = {
+	{
+		.compatible = "amcc,ppc4xx-gpio",
+	},
+	{}
+};
+
+static struct of_platform_driver ppc4xx_gpiochip_driver = {
+	.name = "gpio",
+	.match_table = ppc4xx_gpiochip_match,
+	.probe = ppc4xx_gpiochip_probe,
+	.remove = ppc4xx_gpiochip_remove,
+};
+
+static int __init ppc4xx_gpio_init(void)
+{
+	if (of_register_platform_driver(&ppc4xx_gpiochip_driver))
+		printk(KERN_ERR "Unable to register GPIO driver\n");
+
+	return 0;
+}
+
+
+/* Make sure we get initialised before anyone else tries to use us */
+subsys_initcall(ppc4xx_gpio_init);
+
+/* No exit call at the moment as we cannot unregister of gpio chips */
+
+MODULE_DESCRIPTION("AMCC PPC4xx gpio driver");
+MODULE_AUTHOR("Steve Falco <sfalco@harris.com");
+MODULE_LICENSE("GPL v2");
+