drivers/uio/uio_pdrv_genirq.c

   1 /*
   2  * drivers/uio/uio_pdrv_genirq.c
   3  *
   4  * Userspace I/O platform driver with generic IRQ handling code.
   5  *
   6  * Copyright (C) 2008 Magnus Damm
   7  *
   8  * Based on uio_pdrv.c by Uwe Kleine-Koenig,
   9  * Copyright (C) 2008 by Digi International Inc.
  10  * All rights reserved.
  11  *
  12  * This program is free software; you can redistribute it and/or modify it
  13  * under the terms of the GNU General Public License version 2 as published by
  14  * the Free Software Foundation.
  15  */
  16
  17 #include <linux/platform_device.h>
  18 #include <linux/uio_driver.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/bitops.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/stringify.h>
  23
  24 #define DRIVER_NAME "uio_pdrv_genirq"
  25
  26 struct uio_pdrv_genirq_platdata {
  27         struct uio_info *uioinfo;
  28         spinlock_t lock;
  29         unsigned long flags;
  30 };
  31
  32 static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info)
  33 {
  34         struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
  35
  36         /* Just disable the interrupt in the interrupt controller, and
  37          * remember the state so we can allow user space to enable it later.
  38          */
  39
  40         if (!test_and_set_bit(0, &priv->flags))
  41                 disable_irq_nosync(irq);
  42
  43         return IRQ_HANDLED;
  44 }
  45
  46 static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
  47 {
  48         struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
  49         unsigned long flags;
  50
  51         /* Allow user space to enable and disable the interrupt
  52          * in the interrupt controller, but keep track of the
  53          * state to prevent per-irq depth damage.
  54          *
  55          * Serialize this operation to support multiple tasks.
  56          */
  57
  58         spin_lock_irqsave(&priv->lock, flags);
  59         if (irq_on) {
  60                 if (test_and_clear_bit(0, &priv->flags))
  61                         enable_irq(dev_info->irq);
  62         } else {
  63                 if (!test_and_set_bit(0, &priv->flags))
  64                         disable_irq(dev_info->irq);
  65         }
  66         spin_unlock_irqrestore(&priv->lock, flags);
  67
  68         return 0;
  69 }
  70
  71 static int uio_pdrv_genirq_probe(struct platform_device *pdev)
  72 {
  73         struct uio_info *uioinfo = pdev->dev.platform_data;
  74         struct uio_pdrv_genirq_platdata *priv;
  75         struct uio_mem *uiomem;
  76         int ret = -EINVAL;
  77         int i;
  78
  79         if (!uioinfo || !uioinfo->name || !uioinfo->version) {
  80                 dev_err(&pdev->dev, "missing platform_data\n");
  81                 goto bad0;
  82         }
  83
  84         if (uioinfo->handler || uioinfo->irqcontrol ||
  85             uioinfo->irq_flags & IRQF_SHARED) {
  86                 dev_err(&pdev->dev, "interrupt configuration error\n");
  87                 goto bad0;
  88         }
  89
  90         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
  91         if (!priv) {
  92                 ret = -ENOMEM;
  93                 dev_err(&pdev->dev, "unable to kmalloc\n");
  94                 goto bad0;
  95         }
  96
  97         priv->uioinfo = uioinfo;
  98         spin_lock_init(&priv->lock);
  99         priv->flags = 0; /* interrupt is enabled to begin with */
 100
 101         uiomem = &uioinfo->mem[0];
 102
 103         for (i = 0; i < pdev->num_resources; ++i) {
 104                 struct resource *r = &pdev->resource[i];
 105
 106                 if (r->flags != IORESOURCE_MEM)
 107                         continue;
 108
 109                 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
 110                         dev_warn(&pdev->dev, "device has more than "
 111                                         __stringify(MAX_UIO_MAPS)
 112                                         " I/O memory resources.\n");
 113                         break;
 114                 }
 115
 116                 uiomem->memtype = UIO_MEM_PHYS;
 117                 uiomem->addr = r->start;
 118                 uiomem->size = r->end - r->start + 1;
 119                 ++uiomem;
 120         }
 121
 122         while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
 123                 uiomem->size = 0;
 124                 ++uiomem;
 125         }
 126
 127         /* This driver requires no hardware specific kernel code to handle
 128          * interrupts. Instead, the interrupt handler simply disables the
 129          * interrupt in the interrupt controller. User space is responsible
 130          * for performing hardware specific acknowledge and re-enabling of
 131          * the interrupt in the interrupt controller.
 132          *
 133          * Interrupt sharing is not supported.
 134          */
 135
 136         uioinfo->irq_flags |= IRQF_DISABLED;
 137         uioinfo->handler = uio_pdrv_genirq_handler;
 138         uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
 139         uioinfo->priv = priv;
 140
 141         ret = uio_register_device(&pdev->dev, priv->uioinfo);
 142         if (ret) {
 143                 dev_err(&pdev->dev, "unable to register uio device\n");
 144                 goto bad1;
 145         }
 146
 147         platform_set_drvdata(pdev, priv);
 148         return 0;
 149  bad1:
 150         kfree(priv);
 151  bad0:
 152         return ret;
 153 }
 154
 155 static int uio_pdrv_genirq_remove(struct platform_device *pdev)
 156 {
 157         struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev);
 158
 159         uio_unregister_device(priv->uioinfo);
 160         kfree(priv);
 161         return 0;
 162 }
 163
 164 static struct platform_driver uio_pdrv_genirq = {
 165         .probe = uio_pdrv_genirq_probe,
 166         .remove = uio_pdrv_genirq_remove,
 167         .driver = {
 168                 .name = DRIVER_NAME,
 169                 .owner = THIS_MODULE,
 170         },
 171 };
 172
 173 static int __init uio_pdrv_genirq_init(void)
 174 {
 175         return platform_driver_register(&uio_pdrv_genirq);
 176 }
 177
 178 static void __exit uio_pdrv_genirq_exit(void)
 179 {
 180         platform_driver_unregister(&uio_pdrv_genirq);
 181 }
 182
 183 module_init(uio_pdrv_genirq_init);
 184 module_exit(uio_pdrv_genirq_exit);
 185
 186 MODULE_AUTHOR("Magnus Damm");
 187 MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
 188 MODULE_LICENSE("GPL v2");
 189 MODULE_ALIAS("platform:" DRIVER_NAME);