Re: [PATCH][RESEND] uio: uio_pdrv_genirq V3

From: Hans J. Koch
Date: Tue Jul 29 2008 - 08:29:20 EST


On Tue, Jul 29, 2008 at 09:10:15PM +0900, Magnus Damm wrote:
> From: Magnus Damm <damm@xxxxxxxxxx>
>
> This is V3 of uio_pdrv_genirq.c, a platform driver for UIO with
> generic IRQ handling code. This driver is very similar to the regular
> UIO platform driver, but is only suitable for devices that are
> connected to the interrupt controller using unique interrupt lines.

Hi Magnus,
I already sent this to Greg on July, 15. I guess this will be merged
soon. Greg was probably busy with tons of other stuff during the merge
window.

Thanks,
Hans

>
> The uio_pdrv_genirq driver includes generic interrupt handling code
> which disables the serviced interrupt in the interrupt controller
> and makes the user space driver responsible for acknowledging the
> interrupt in the device and reenabling the interrupt in the interrupt
> controller.
>
> Shared interrupts are not supported since the in-kernel interrupt
> handler will disable the interrupt line in the interrupt controller,
> and in a shared interrupt configuration this will stop other devices
> from delivering interrupts.
>
> Signed-off-by: Magnus Damm <damm@xxxxxxxxxx>
> Signed-off-by: Hans J. Koch <hjk@xxxxxxxxxxxxx>
> ---
>
> Patch sent to lkml on July 11th, please pick up.
> Platform data already in place in arch/sh/kernel/cpu/sh4a/...
>
> Changes since V2
> - readded bitops
> - removed irq handler spinlock to fix potential deadlock
> - kept irq control spinlock to serialize user space access
>
> Changes since V1
> - allow user space to enable _and_ disable the interrupt
> - replaced bitops with spinlock + irq_disabled variable
> - renamed pdata variable name to priv
>
> drivers/uio/Kconfig | 13 ++
> drivers/uio/Makefile | 1
> drivers/uio/uio_pdrv_genirq.c | 188 +++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 202 insertions(+)
>
> --- 0001/drivers/uio/Kconfig
> +++ work/drivers/uio/Kconfig 2008-07-29 20:59:36.000000000 +0900
> @@ -33,6 +33,19 @@ config UIO_PDRV
>
> 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
> --- 0001/drivers/uio/Makefile
> +++ work/drivers/uio/Makefile 2008-07-29 20:59:36.000000000 +0900
> @@ -1,4 +1,5 @@
> 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
> --- /dev/null
> +++ work/drivers/uio/uio_pdrv_genirq.c 2008-07-29 20:59:36.000000000 +0900
> @@ -0,0 +1,188 @@
> +/*
> + * 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);
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