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 #include <linux/of.h>
  27 #include <linux/of_platform.h>
  28 #include <linux/of_address.h>
  29
  30 #define DRIVER_NAME "uio_pdrv_genirq"
  31
  32 struct uio_pdrv_genirq_platdata {
  33         struct uio_info *uioinfo;
  34         spinlock_t lock;
  35         unsigned long flags;
  36         struct platform_device *pdev;
  37 };
  38
  39 static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode)
  40 {
  41         struct uio_pdrv_genirq_platdata *priv = info->priv;
  42
  43         /* Wait until the Runtime PM code has woken up the device */
  44         pm_runtime_get_sync(&priv->pdev->dev);
  45         return 0;
  46 }
  47
  48 static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode)
  49 {
  50         struct uio_pdrv_genirq_platdata *priv = info->priv;
  51
  52         /* Tell the Runtime PM code that the device has become idle */
  53         pm_runtime_put_sync(&priv->pdev->dev);
  54         return 0;
  55 }
  56
  57 static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info)
  58 {
  59         struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
  60
  61         /* Just disable the interrupt in the interrupt controller, and
  62          * remember the state so we can allow user space to enable it later.
  63          */
  64
  65         if (!test_and_set_bit(0, &priv->flags))
  66                 disable_irq_nosync(irq);
  67
  68         return IRQ_HANDLED;
  69 }
  70
  71 static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
  72 {
  73         struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
  74         unsigned long flags;
  75
  76         /* Allow user space to enable and disable the interrupt
  77          * in the interrupt controller, but keep track of the
  78          * state to prevent per-irq depth damage.
  79          *
  80          * Serialize this operation to support multiple tasks.
  81          */
  82
  83         spin_lock_irqsave(&priv->lock, flags);
  84         if (irq_on) {
  85                 if (test_and_clear_bit(0, &priv->flags))
  86                         enable_irq(dev_info->irq);
  87         } else {
  88                 if (!test_and_set_bit(0, &priv->flags))
  89                         disable_irq(dev_info->irq);
  90         }
  91         spin_unlock_irqrestore(&priv->lock, flags);
  92
  93         return 0;
  94 }
  95
  96 static int uio_pdrv_genirq_probe(struct platform_device *pdev)
  97 {
  98         struct uio_info *uioinfo = pdev->dev.platform_data;
  99         struct uio_pdrv_genirq_platdata *priv;
 100         struct uio_mem *uiomem;
 101         int ret = -EINVAL;
 102         int i;
 103
 104         if (!uioinfo) {
 105                 int irq;
 106
 107                 /* alloc uioinfo for one device */
 108                 uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
 109                 if (!uioinfo) {
 110                         ret = -ENOMEM;
 111                         dev_err(&pdev->dev, "unable to kmalloc\n");
 112                         goto bad2;
 113                 }
 114                 uioinfo->name = pdev->dev.of_node->name;
 115                 uioinfo->version = "devicetree";
 116
 117                 /* Multiple IRQs are not supported */
 118                 irq = platform_get_irq(pdev, 0);
 119                 if (irq == -ENXIO)
 120                         uioinfo->irq = UIO_IRQ_NONE;
 121                 else
 122                         uioinfo->irq = irq;
 123         }
 124
 125         if (!uioinfo || !uioinfo->name || !uioinfo->version) {
 126                 dev_err(&pdev->dev, "missing platform_data\n");
 127                 goto bad0;
 128         }
 129
 130         if (uioinfo->handler || uioinfo->irqcontrol ||
 131             uioinfo->irq_flags & IRQF_SHARED) {
 132                 dev_err(&pdev->dev, "interrupt configuration error\n");
 133                 goto bad0;
 134         }
 135
 136         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 137         if (!priv) {
 138                 ret = -ENOMEM;
 139                 dev_err(&pdev->dev, "unable to kmalloc\n");
 140                 goto bad0;
 141         }
 142
 143         priv->uioinfo = uioinfo;
 144         spin_lock_init(&priv->lock);
 145         priv->flags = 0; /* interrupt is enabled to begin with */
 146         priv->pdev = pdev;
 147
 148         uiomem = &uioinfo->mem[0];
 149
 150         for (i = 0; i < pdev->num_resources; ++i) {
 151                 struct resource *r = &pdev->resource[i];
 152
 153                 if (r->flags != IORESOURCE_MEM)
 154                         continue;
 155
 156                 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
 157                         dev_warn(&pdev->dev, "device has more than "
 158                                         __stringify(MAX_UIO_MAPS)
 159                                         " I/O memory resources.\n");
 160                         break;
 161                 }
 162
 163                 uiomem->memtype = UIO_MEM_PHYS;
 164                 uiomem->addr = r->start;
 165                 uiomem->size = r->end - r->start + 1;
 166                 ++uiomem;
 167         }
 168
 169         while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
 170                 uiomem->size = 0;
 171                 ++uiomem;
 172         }
 173
 174         /* This driver requires no hardware specific kernel code to handle
 175          * interrupts. Instead, the interrupt handler simply disables the
 176          * interrupt in the interrupt controller. User space is responsible
 177          * for performing hardware specific acknowledge and re-enabling of
 178          * the interrupt in the interrupt controller.
 179          *
 180          * Interrupt sharing is not supported.
 181          */
 182
 183         uioinfo->handler = uio_pdrv_genirq_handler;
 184         uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
 185         uioinfo->open = uio_pdrv_genirq_open;
 186         uioinfo->release = uio_pdrv_genirq_release;
 187         uioinfo->priv = priv;
 188
 189         /* Enable Runtime PM for this device:
 190          * The device starts in suspended state to allow the hardware to be
 191          * turned off by default. The Runtime PM bus code should power on the
 192          * hardware and enable clocks at open().
 193          */
 194         pm_runtime_enable(&pdev->dev);
 195
 196         ret = uio_register_device(&pdev->dev, priv->uioinfo);
 197         if (ret) {
 198                 dev_err(&pdev->dev, "unable to register uio device\n");
 199                 goto bad1;
 200         }
 201
 202         platform_set_drvdata(pdev, priv);
 203         return 0;
 204  bad1:
 205         kfree(priv);
 206         pm_runtime_disable(&pdev->dev);
 207  bad0:
 208         /* kfree uioinfo for OF */
 209         if (pdev->dev.of_node)
 210                 kfree(uioinfo);
 211  bad2:
 212         return ret;
 213 }
 214
 215 static int uio_pdrv_genirq_remove(struct platform_device *pdev)
 216 {
 217         struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev);
 218
 219         uio_unregister_device(priv->uioinfo);
 220         pm_runtime_disable(&pdev->dev);
 221
 222         priv->uioinfo->handler = NULL;
 223         priv->uioinfo->irqcontrol = NULL;
 224
 225         /* kfree uioinfo for OF */
 226         if (pdev->dev.of_node)
 227                 kfree(priv->uioinfo);
 228
 229         kfree(priv);
 230         return 0;
 231 }
 232
 233 static int uio_pdrv_genirq_runtime_nop(struct device *dev)
 234 {
 235         /* Runtime PM callback shared between ->runtime_suspend()
 236          * and ->runtime_resume(). Simply returns success.
 237          *
 238          * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
 239          * are used at open() and release() time. This allows the
 240          * Runtime PM code to turn off power to the device while the
 241          * device is unused, ie before open() and after release().
 242          *
 243          * This Runtime PM callback does not need to save or restore
 244          * any registers since user space is responsbile for hardware
 245          * register reinitialization after open().
 246          */
 247         return 0;
 248 }
 249
 250 static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
 251         .runtime_suspend = uio_pdrv_genirq_runtime_nop,
 252         .runtime_resume = uio_pdrv_genirq_runtime_nop,
 253 };
 254
 255 #ifdef CONFIG_OF
 256 static const struct of_device_id __devinitconst uio_of_genirq_match[] = {
 257         { /* empty for now */ },
 258 };
 259 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
 260 #else
 261 # define uio_of_genirq_match NULL
 262 #endif
 263
 264 static struct platform_driver uio_pdrv_genirq = {
 265         .probe = uio_pdrv_genirq_probe,
 266         .remove = uio_pdrv_genirq_remove,
 267         .driver = {
 268                 .name = DRIVER_NAME,
 269                 .owner = THIS_MODULE,
 270                 .pm = &uio_pdrv_genirq_dev_pm_ops,
 271                 .of_match_table = uio_of_genirq_match,
 272         },
 273 };
 274
 275 static int __init uio_pdrv_genirq_init(void)
 276 {
 277         return platform_driver_register(&uio_pdrv_genirq);
 278 }
 279
 280 static void __exit uio_pdrv_genirq_exit(void)
 281 {
 282         platform_driver_unregister(&uio_pdrv_genirq);
 283 }
 284
 285 module_init(uio_pdrv_genirq_init);
 286 module_exit(uio_pdrv_genirq_exit);
 287
 288 MODULE_AUTHOR("Magnus Damm");
 289 MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
 290 MODULE_LICENSE("GPL v2");
 291 MODULE_ALIAS("platform:" DRIVER_NAME);