UIO: generic irq handling for some uio platform devices

	  If you don't know what to do here, say N.

config UIO_PDRV_GENIRQ

	tristate "Userspace I/O platform driver with generic IRQ handling"

	help

	  Platform driver for Userspace I/O devices, including generic

	  interrupt handling code. Shared interrupts are not supported.

	  This kernel driver requires that the matching userspace driver

	  handles interrupts in a special way. Userspace is responsible

	  for acknowledging the hardware device if needed, and re-enabling

	  interrupts in the interrupt controller using the write() syscall.

	  If you don't know what to do here, say N.

config UIO_SMX

	tristate "SMX cryptengine UIO interface"

	default n

obj-$(CONFIG_UIO)	+= uio.o

obj-$(CONFIG_UIO_CIF)	+= uio_cif.o

obj-$(CONFIG_UIO_PDRV)	+= uio_pdrv.o

obj-$(CONFIG_UIO_PDRV_GENIRQ)	+= uio_pdrv_genirq.o

obj-$(CONFIG_UIO_SMX)	+= uio_smx.o

/*

 * drivers/uio/uio_pdrv_genirq.c

 *

 * Userspace I/O platform driver with generic IRQ handling code.

 *

 * Copyright (C) 2008 Magnus Damm

 *

 * Based on uio_pdrv.c by Uwe Kleine-Koenig,

 * Copyright (C) 2008 by Digi International Inc.

 * All rights reserved.

 *

 * 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.

 */

#include <linux/platform_device.h>

#include <linux/uio_driver.h>

#include <linux/spinlock.h>

#include <linux/bitops.h>

#include <linux/interrupt.h>

#include <linux/stringify.h>

#define DRIVER_NAME "uio_pdrv_genirq"

struct uio_pdrv_genirq_platdata {

	struct uio_info *uioinfo;

	spinlock_t lock;

	unsigned long flags;

};

static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info)

{

	struct uio_pdrv_genirq_platdata *priv = dev_info->priv;

	/* Just disable the interrupt in the interrupt controller, and

	 * remember the state so we can allow user space to enable it later.

	 */

	if (!test_and_set_bit(0, &priv->flags))

		disable_irq_nosync(irq);

	return IRQ_HANDLED;

}

static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)

{

	struct uio_pdrv_genirq_platdata *priv = dev_info->priv;

	unsigned long flags;

	/* Allow user space to enable and disable the interrupt

	 * in the interrupt controller, but keep track of the

	 * state to prevent per-irq depth damage.

	 *

	 * Serialize this operation to support multiple tasks.

	 */

	spin_lock_irqsave(&priv->lock, flags);

	if (irq_on) {

		if (test_and_clear_bit(0, &priv->flags))

			enable_irq(dev_info->irq);

	} else {

		if (!test_and_set_bit(0, &priv->flags))

			disable_irq(dev_info->irq);

	}

	spin_unlock_irqrestore(&priv->lock, flags);

	return 0;

}

static int uio_pdrv_genirq_probe(struct platform_device *pdev)

{

	struct uio_info *uioinfo = pdev->dev.platform_data;

	struct uio_pdrv_genirq_platdata *priv;

	struct uio_mem *uiomem;

	int ret = -EINVAL;

	int i;

	if (!uioinfo || !uioinfo->name || !uioinfo->version) {

		dev_err(&pdev->dev, "missing platform_data\n");

		goto bad0;

	}

	if (uioinfo->handler || uioinfo->irqcontrol || uioinfo->irq_flags) {

		dev_err(&pdev->dev, "interrupt configuration error\n");

		goto bad0;

	}

	priv = kzalloc(sizeof(*priv), GFP_KERNEL);

	if (!priv) {

		ret = -ENOMEM;

		dev_err(&pdev->dev, "unable to kmalloc\n");

		goto bad0;

	}

	priv->uioinfo = uioinfo;

	spin_lock_init(&priv->lock);

	priv->flags = 0; /* interrupt is enabled to begin with */

	uiomem = &uioinfo->mem[0];

	for (i = 0; i < pdev->num_resources; ++i) {

		struct resource *r = &pdev->resource[i];

		if (r->flags != IORESOURCE_MEM)

			continue;

		if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {

			dev_warn(&pdev->dev, "device has more than "

					__stringify(MAX_UIO_MAPS)

					" I/O memory resources.\n");

			break;

		}

		uiomem->memtype = UIO_MEM_PHYS;

		uiomem->addr = r->start;

		uiomem->size = r->end - r->start + 1;

		++uiomem;

	}

	while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {

		uiomem->size = 0;

		++uiomem;

	}

	/* This driver requires no hardware specific kernel code to handle

	 * interrupts. Instead, the interrupt handler simply disables the

	 * interrupt in the interrupt controller. User space is responsible

	 * for performing hardware specific acknowledge and re-enabling of

	 * the interrupt in the interrupt controller.

	 *

	 * Interrupt sharing is not supported.

	 */

	uioinfo->irq_flags = IRQF_DISABLED;

	uioinfo->handler = uio_pdrv_genirq_handler;

	uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;

	uioinfo->priv = priv;

	ret = uio_register_device(&pdev->dev, priv->uioinfo);

	if (ret) {

		dev_err(&pdev->dev, "unable to register uio device\n");

		goto bad1;

	}

	platform_set_drvdata(pdev, priv);

	return 0;

 bad1:

	kfree(priv);

 bad0:

	return ret;

}

static int uio_pdrv_genirq_remove(struct platform_device *pdev)

{

	struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev);

	uio_unregister_device(priv->uioinfo);

	kfree(priv);

	return 0;

}

static struct platform_driver uio_pdrv_genirq = {

	.probe = uio_pdrv_genirq_probe,

	.remove = uio_pdrv_genirq_remove,

	.driver = {

		.name = DRIVER_NAME,

		.owner = THIS_MODULE,

	},

};

static int __init uio_pdrv_genirq_init(void)

{

	return platform_driver_register(&uio_pdrv_genirq);

}

static void __exit uio_pdrv_genirq_exit(void)

{

	platform_driver_unregister(&uio_pdrv_genirq);

}

module_init(uio_pdrv_genirq_init);

module_exit(uio_pdrv_genirq_exit);

MODULE_AUTHOR("Magnus Damm");

MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");

MODULE_LICENSE("GPL v2");

MODULE_ALIAS("platform:" DRIVER_NAME);