/*
* 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>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#define DRIVER_NAME "uio_pdrv_genirq"
struct uio_pdrv_genirq_platdata {
struct uio_info *uioinfo;
spinlock_t lock;
unsigned long flags;
struct platform_device *pdev;
};
static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode)
{
struct uio_pdrv_genirq_platdata *priv = info->priv;
/* Wait until the Runtime PM code has woken up the device */
pm_runtime_get_sync(&priv->pdev->dev);
return 0;
}
static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode)
{
struct uio_pdrv_genirq_platdata *priv = info->priv;
/* Tell the Runtime PM code that the device has become idle */
pm_runtime_put_sync(&priv->pdev->dev);
return 0;
}
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 & IRQF_SHARED) {
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 */
priv->pdev = pdev;
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->handler = uio_pdrv_genirq_handler;
uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
uioinfo->open = uio_pdrv_genirq_open;
uioinfo->release = uio_pdrv_genirq_release;
uioinfo->priv = priv;
/* Enable Runtime PM for this device:
* The device starts in suspended state to allow the hardware to be
* turned off by default. The Runtime PM bus code should power on the
* hardware and enable clocks at open().
*/
pm_runtime_enable(&pdev->dev);
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);
pm_runtime_disable(&pdev->dev);
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);
pm_runtime_disable(&pdev->dev);
kfree(priv);
return 0;
}
static int uio_pdrv_genirq_runtime_nop(struct device *dev)
{
/* Runtime PM callback shared between ->runtime_suspend()
* and ->runtime_resume(). Simply returns success.
*
* In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
* are used at open() and release() time. This allows the
* Runtime PM code to turn off power to the device while the
* device is unused, ie before open() and after release().
*
* This Runtime PM callback does not need to save or restore
* any registers since user space is responsbile for hardware
* register reinitialization after open().
*/
return 0;
}
static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
.runtime_suspend = uio_pdrv_genirq_runtime_nop,
.runtime_resume = uio_pdrv_genirq_runtime_nop,
};
static struct platform_driver uio_pdrv_genirq = {
.probe = uio_pdrv_genirq_probe,
.remove = uio_pdrv_genirq_remove,
.driver = {
.name = DRIVER_NAME,
.owner = THIS_MODULE,
.pm = &uio_pdrv_genirq_dev_pm_ops,
},
};
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);
