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