/* * 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 & 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 */ 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);