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 #include <linux/pm_runtime.h>
  24 #include <linux/slab.h>
  25
  26 #define DRIVER_NAME "uio_pdrv_genirq"
  27
  28 struct uio_pdrv_genirq_platdata {
  29         struct uio_info *uioinfo;
  30         spinlock_t lock;
  31         unsigned long flags;
  32         struct platform_device *pdev;
  33 };
  34
  35 static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode)
  36 {
  37         struct uio_pdrv_genirq_platdata *priv = info->priv;
  38
  39         /* Wait until the Runtime PM code has woken up the device */
  40         pm_runtime_get_sync(&priv->pdev->dev);
  41         return 0;
  42 }
  43
  44 static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode)
  45 {
  46         struct uio_pdrv_genirq_platdata *priv = info->priv;
  47
  48         /* Tell the Runtime PM code that the device has become idle */
  49         pm_runtime_put_sync(&priv->pdev->dev);
  50         return 0;
  51 }
  52
  53 static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info)
  54 {
  55         struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
  56
  57         /* Just disable the interrupt in the interrupt controller, and
  58          * remember the state so we can allow user space to enable it later.
  59          */
  60
  61         if (!test_and_set_bit(0, &priv->flags))
  62                 disable_irq_nosync(irq);
  63
  64         return IRQ_HANDLED;
  65 }
  66
  67 static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
  68 {
  69         struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
  70         unsigned long flags;
  71
  72         /* Allow user space to enable and disable the interrupt
  73          * in the interrupt controller, but keep track of the
  74          * state to prevent per-irq depth damage.
  75          *
  76          * Serialize this operation to support multiple tasks.
  77          */
  78
  79         spin_lock_irqsave(&priv->lock, flags);
  80         if (irq_on) {
  81                 if (test_and_clear_bit(0, &priv->flags))
  82                         enable_irq(dev_info->irq);
  83         } else {
  84                 if (!test_and_set_bit(0, &priv->flags))
  85                         disable_irq(dev_info->irq);
  86         }
  87         spin_unlock_irqrestore(&priv->lock, flags);
  88
  89         return 0;
  90 }
  91
  92 static int uio_pdrv_genirq_probe(struct platform_device *pdev)
  93 {
  94         struct uio_info *uioinfo = pdev->dev.platform_data;
  95         struct uio_pdrv_genirq_platdata *priv;
  96         struct uio_mem *uiomem;
  97         int ret = -EINVAL;
  98         int i;
  99
 100         if (!uioinfo || !uioinfo->name || !uioinfo->version) {
 101                 dev_err(&pdev->dev, "missing platform_data\n");
 102                 goto bad0;
 103         }
 104
 105         if (uioinfo->handler || uioinfo->irqcontrol ||
 106             uioinfo->irq_flags & IRQF_SHARED) {
 107                 dev_err(&pdev->dev, "interrupt configuration error\n");
 108                 goto bad0;
 109         }
 110
 111         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 112         if (!priv) {
 113                 ret = -ENOMEM;
 114                 dev_err(&pdev->dev, "unable to kmalloc\n");
 115                 goto bad0;
 116         }
 117
 118         priv->uioinfo = uioinfo;
 119         spin_lock_init(&priv->lock);
 120         priv->flags = 0; /* interrupt is enabled to begin with */
 121         priv->pdev = pdev;
 122
 123         uiomem = &uioinfo->mem[0];
 124
 125         for (i = 0; i < pdev->num_resources; ++i) {
 126                 struct resource *r = &pdev->resource[i];
 127
 128                 if (r->flags != IORESOURCE_MEM)
 129                         continue;
 130
 131                 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
 132                         dev_warn(&pdev->dev, "device has more than "
 133                                         __stringify(MAX_UIO_MAPS)
 134                                         " I/O memory resources.\n");
 135                         break;
 136                 }
 137
 138                 uiomem->memtype = UIO_MEM_PHYS;
 139                 uiomem->addr = r->start;
 140                 uiomem->size = r->end - r->start + 1;
 141                 ++uiomem;
 142         }
 143
 144         while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
 145                 uiomem->size = 0;
 146                 ++uiomem;
 147         }
 148
 149         /* This driver requires no hardware specific kernel code to handle
 150          * interrupts. Instead, the interrupt handler simply disables the
 151          * interrupt in the interrupt controller. User space is responsible
 152          * for performing hardware specific acknowledge and re-enabling of
 153          * the interrupt in the interrupt controller.
 154          *
 155          * Interrupt sharing is not supported.
 156          */
 157
 158         uioinfo->handler = uio_pdrv_genirq_handler;
 159         uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
 160         uioinfo->open = uio_pdrv_genirq_open;
 161         uioinfo->release = uio_pdrv_genirq_release;
 162         uioinfo->priv = priv;
 163
 164         /* Enable Runtime PM for this device:
 165          * The device starts in suspended state to allow the hardware to be
 166          * turned off by default. The Runtime PM bus code should power on the
 167          * hardware and enable clocks at open().
 168          */
 169         pm_runtime_enable(&pdev->dev);
 170
 171         ret = uio_register_device(&pdev->dev, priv->uioinfo);
 172         if (ret) {
 173                 dev_err(&pdev->dev, "unable to register uio device\n");
 174                 goto bad1;
 175         }
 176
 177         platform_set_drvdata(pdev, priv);
 178         return 0;
 179  bad1:
 180         kfree(priv);
 181         pm_runtime_disable(&pdev->dev);
 182  bad0:
 183         return ret;
 184 }
 185
 186 static int uio_pdrv_genirq_remove(struct platform_device *pdev)
 187 {
 188         struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev);
 189
 190         uio_unregister_device(priv->uioinfo);
 191         pm_runtime_disable(&pdev->dev);
 192
 193         priv->uioinfo->handler = NULL;
 194         priv->uioinfo->irqcontrol = NULL;
 195
 196         kfree(priv);
 197         return 0;
 198 }
 199
 200 static int uio_pdrv_genirq_runtime_nop(struct device *dev)
 201 {
 202         /* Runtime PM callback shared between ->runtime_suspend()
 203          * and ->runtime_resume(). Simply returns success.
 204          *
 205          * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
 206          * are used at open() and release() time. This allows the
 207          * Runtime PM code to turn off power to the device while the
 208          * device is unused, ie before open() and after release().
 209          *
 210          * This Runtime PM callback does not need to save or restore
 211          * any registers since user space is responsbile for hardware
 212          * register reinitialization after open().
 213          */
 214         return 0;
 215 }
 216
 217 static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
 218         .runtime_suspend = uio_pdrv_genirq_runtime_nop,
 219         .runtime_resume = uio_pdrv_genirq_runtime_nop,
 220 };
 221
 222 static struct platform_driver uio_pdrv_genirq = {
 223         .probe = uio_pdrv_genirq_probe,
 224         .remove = uio_pdrv_genirq_remove,
 225         .driver = {
 226                 .name = DRIVER_NAME,
 227                 .owner = THIS_MODULE,
 228                 .pm = &uio_pdrv_genirq_dev_pm_ops,
 229         },
 230 };
 231
 232 static int __init uio_pdrv_genirq_init(void)
 233 {
 234         return platform_driver_register(&uio_pdrv_genirq);
 235 }
 236
 237 static void __exit uio_pdrv_genirq_exit(void)
 238 {
 239         platform_driver_unregister(&uio_pdrv_genirq);
 240 }
 241
 242 module_init(uio_pdrv_genirq_init);
 243 module_exit(uio_pdrv_genirq_exit);
 244
 245 MODULE_AUTHOR("Magnus Damm");
 246 MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
 247 MODULE_LICENSE("GPL v2");
 248 MODULE_ALIAS("platform:" DRIVER_NAME);