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/module.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/stringify.h>
  24 #include <linux/pm_runtime.h>
  25 #include <linux/slab.h>
  26
  27 #include <linux/of.h>
  28 #include <linux/of_platform.h>
  29 #include <linux/of_address.h>
  30
  31 #define DRIVER_NAME "uio_pdrv_genirq"
  32
  33 struct uio_pdrv_genirq_platdata {
  34         struct uio_info *uioinfo;
  35         spinlock_t lock;
  36         unsigned long flags;
  37         struct platform_device *pdev;
  38 };
  39
  40 static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode)
  41 {
  42         struct uio_pdrv_genirq_platdata *priv = info->priv;
  43
  44         /* Wait until the Runtime PM code has woken up the device */
  45         pm_runtime_get_sync(&priv->pdev->dev);
  46         return 0;
  47 }
  48
  49 static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode)
  50 {
  51         struct uio_pdrv_genirq_platdata *priv = info->priv;
  52
  53         /* Tell the Runtime PM code that the device has become idle */
  54         pm_runtime_put_sync(&priv->pdev->dev);
  55         return 0;
  56 }
  57
  58 static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info)
  59 {
  60         struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
  61
  62         /* Just disable the interrupt in the interrupt controller, and
  63          * remember the state so we can allow user space to enable it later.
  64          */
  65
  66         if (!test_and_set_bit(0, &priv->flags))
  67                 disable_irq_nosync(irq);
  68
  69         return IRQ_HANDLED;
  70 }
  71
  72 static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
  73 {
  74         struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
  75         unsigned long flags;
  76
  77         /* Allow user space to enable and disable the interrupt
  78          * in the interrupt controller, but keep track of the
  79          * state to prevent per-irq depth damage.
  80          *
  81          * Serialize this operation to support multiple tasks.
  82          */
  83
  84         spin_lock_irqsave(&priv->lock, flags);
  85         if (irq_on) {
  86                 if (test_and_clear_bit(0, &priv->flags))
  87                         enable_irq(dev_info->irq);
  88         } else {
  89                 if (!test_and_set_bit(0, &priv->flags))
  90                         disable_irq(dev_info->irq);
  91         }
  92         spin_unlock_irqrestore(&priv->lock, flags);
  93
  94         return 0;
  95 }
  96
  97 static int uio_pdrv_genirq_probe(struct platform_device *pdev)
  98 {
  99         struct uio_info *uioinfo = pdev->dev.platform_data;
 100         struct uio_pdrv_genirq_platdata *priv;
 101         struct uio_mem *uiomem;
 102         int ret = -EINVAL;
 103         int i;
 104
 105         if (!uioinfo) {
 106                 int irq;
 107
 108                 /* alloc uioinfo for one device */
 109                 uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
 110                 if (!uioinfo) {
 111                         ret = -ENOMEM;
 112                         dev_err(&pdev->dev, "unable to kmalloc\n");
 113                         goto bad2;
 114                 }
 115                 uioinfo->name = pdev->dev.of_node->name;
 116                 uioinfo->version = "devicetree";
 117
 118                 /* Multiple IRQs are not supported */
 119                 irq = platform_get_irq(pdev, 0);
 120                 if (irq == -ENXIO)
 121                         uioinfo->irq = UIO_IRQ_NONE;
 122                 else
 123                         uioinfo->irq = irq;
 124         }
 125
 126         if (!uioinfo || !uioinfo->name || !uioinfo->version) {
 127                 dev_err(&pdev->dev, "missing platform_data\n");
 128                 goto bad0;
 129         }
 130
 131         if (uioinfo->handler || uioinfo->irqcontrol ||
 132             uioinfo->irq_flags & IRQF_SHARED) {
 133                 dev_err(&pdev->dev, "interrupt configuration error\n");
 134                 goto bad0;
 135         }
 136
 137         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 138         if (!priv) {
 139                 ret = -ENOMEM;
 140                 dev_err(&pdev->dev, "unable to kmalloc\n");
 141                 goto bad0;
 142         }
 143
 144         priv->uioinfo = uioinfo;
 145         spin_lock_init(&priv->lock);
 146         priv->flags = 0; /* interrupt is enabled to begin with */
 147         priv->pdev = pdev;
 148
 149         if (!uioinfo->irq) {
 150                 ret = platform_get_irq(pdev, 0);
 151                 if (ret < 0) {
 152                         dev_err(&pdev->dev, "failed to get IRQ\n");
 153                         goto bad0;
 154                 }
 155                 uioinfo->irq = ret;
 156         }
 157         uiomem = &uioinfo->mem[0];
 158
 159         for (i = 0; i < pdev->num_resources; ++i) {
 160                 struct resource *r = &pdev->resource[i];
 161
 162                 if (r->flags != IORESOURCE_MEM)
 163                         continue;
 164
 165                 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
 166                         dev_warn(&pdev->dev, "device has more than "
 167                                         __stringify(MAX_UIO_MAPS)
 168                                         " I/O memory resources.\n");
 169                         break;
 170                 }
 171
 172                 uiomem->memtype = UIO_MEM_PHYS;
 173                 uiomem->addr = r->start;
 174                 uiomem->size = resource_size(r);
 175                 ++uiomem;
 176         }
 177
 178         while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
 179                 uiomem->size = 0;
 180                 ++uiomem;
 181         }
 182
 183         /* This driver requires no hardware specific kernel code to handle
 184          * interrupts. Instead, the interrupt handler simply disables the
 185          * interrupt in the interrupt controller. User space is responsible
 186          * for performing hardware specific acknowledge and re-enabling of
 187          * the interrupt in the interrupt controller.
 188          *
 189          * Interrupt sharing is not supported.
 190          */
 191
 192         uioinfo->handler = uio_pdrv_genirq_handler;
 193         uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
 194         uioinfo->open = uio_pdrv_genirq_open;
 195         uioinfo->release = uio_pdrv_genirq_release;
 196         uioinfo->priv = priv;
 197
 198         /* Enable Runtime PM for this device:
 199          * The device starts in suspended state to allow the hardware to be
 200          * turned off by default. The Runtime PM bus code should power on the
 201          * hardware and enable clocks at open().
 202          */
 203         pm_runtime_enable(&pdev->dev);
 204
 205         ret = uio_register_device(&pdev->dev, priv->uioinfo);
 206         if (ret) {
 207                 dev_err(&pdev->dev, "unable to register uio device\n");
 208                 goto bad1;
 209         }
 210
 211         platform_set_drvdata(pdev, priv);
 212         return 0;
 213  bad1:
 214         kfree(priv);
 215         pm_runtime_disable(&pdev->dev);
 216  bad0:
 217         /* kfree uioinfo for OF */
 218         if (pdev->dev.of_node)
 219                 kfree(uioinfo);
 220  bad2:
 221         return ret;
 222 }
 223
 224 static int uio_pdrv_genirq_remove(struct platform_device *pdev)
 225 {
 226         struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev);
 227
 228         uio_unregister_device(priv->uioinfo);
 229         pm_runtime_disable(&pdev->dev);
 230
 231         priv->uioinfo->handler = NULL;
 232         priv->uioinfo->irqcontrol = NULL;
 233
 234         /* kfree uioinfo for OF */
 235         if (pdev->dev.of_node)
 236                 kfree(priv->uioinfo);
 237
 238         kfree(priv);
 239         return 0;
 240 }
 241
 242 static int uio_pdrv_genirq_runtime_nop(struct device *dev)
 243 {
 244         /* Runtime PM callback shared between ->runtime_suspend()
 245          * and ->runtime_resume(). Simply returns success.
 246          *
 247          * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
 248          * are used at open() and release() time. This allows the
 249          * Runtime PM code to turn off power to the device while the
 250          * device is unused, ie before open() and after release().
 251          *
 252          * This Runtime PM callback does not need to save or restore
 253          * any registers since user space is responsbile for hardware
 254          * register reinitialization after open().
 255          */
 256         return 0;
 257 }
 258
 259 static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
 260         .runtime_suspend = uio_pdrv_genirq_runtime_nop,
 261         .runtime_resume = uio_pdrv_genirq_runtime_nop,
 262 };
 263
 264 #ifdef CONFIG_OF
 265 static const struct of_device_id uio_of_genirq_match[] = {
 266         { /* empty for now */ },
 267 };
 268 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
 269 #else
 270 # define uio_of_genirq_match NULL
 271 #endif
 272
 273 static struct platform_driver uio_pdrv_genirq = {
 274         .probe = uio_pdrv_genirq_probe,
 275         .remove = uio_pdrv_genirq_remove,
 276         .driver = {
 277                 .name = DRIVER_NAME,
 278                 .owner = THIS_MODULE,
 279                 .pm = &uio_pdrv_genirq_dev_pm_ops,
 280                 .of_match_table = uio_of_genirq_match,
 281         },
 282 };
 283
 284 module_platform_driver(uio_pdrv_genirq);
 285
 286 MODULE_AUTHOR("Magnus Damm");
 287 MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
 288 MODULE_LICENSE("GPL v2");
 289 MODULE_ALIAS("platform:" DRIVER_NAME);