diff options
Diffstat (limited to 'drivers/uio/uio_pdrv_genirq.c')
| -rw-r--r-- | drivers/uio/uio_pdrv_genirq.c | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/drivers/uio/uio_pdrv_genirq.c b/drivers/uio/uio_pdrv_genirq.c new file mode 100644 index 000000000000..1f82c83a92ae --- /dev/null +++ b/drivers/uio/uio_pdrv_genirq.c @@ -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); |