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         uiomem = &uioinfo->mem[0];
 150
 151         for (i = 0; i < pdev->num_resources; ++i) {
 152                 struct resource *r = &pdev->resource[i];
 153
 154                 if (r->flags != IORESOURCE_MEM)
 155                         continue;
 156
 157                 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
 158                         dev_warn(&pdev->dev, "device has more than "
 159                                         __stringify(MAX_UIO_MAPS)
 160                                         " I/O memory resources.\n");
 161                         break;
 162                 }
 163
 164                 uiomem->memtype = UIO_MEM_PHYS;
 165                 uiomem->addr = r->start;
 166                 uiomem->size = resource_size(r);
 167                 ++uiomem;
 168         }
 169
 170         while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
 171                 uiomem->size = 0;
 172                 ++uiomem;
 173         }
 174
 175         /* This driver requires no hardware specific kernel code to handle
 176          * interrupts. Instead, the interrupt handler simply disables the
 177          * interrupt in the interrupt controller. User space is responsible
 178          * for performing hardware specific acknowledge and re-enabling of
 179          * the interrupt in the interrupt controller.
 180          *
 181          * Interrupt sharing is not supported.
 182          */
 183
 184         uioinfo->handler = uio_pdrv_genirq_handler;
 185         uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
 186         uioinfo->open = uio_pdrv_genirq_open;
 187         uioinfo->release = uio_pdrv_genirq_release;
 188         uioinfo->priv = priv;
 189
 190         /* Enable Runtime PM for this device:
 191          * The device starts in suspended state to allow the hardware to be
 192          * turned off by default. The Runtime PM bus code should power on the
 193          * hardware and enable clocks at open().
 194          */
 195         pm_runtime_enable(&pdev->dev);
 196
 197         ret = uio_register_device(&pdev->dev, priv->uioinfo);
 198         if (ret) {
 199                 dev_err(&pdev->dev, "unable to register uio device\n");
 200                 goto bad1;
 201         }
 202
 203         platform_set_drvdata(pdev, priv);
 204         return 0;
 205  bad1:
 206         kfree(priv);
 207         pm_runtime_disable(&pdev->dev);
 208  bad0:
 209         /* kfree uioinfo for OF */
 210         if (pdev->dev.of_node)
 211                 kfree(uioinfo);
 212  bad2:
 213         return ret;
 214 }
 215
 216 static int uio_pdrv_genirq_remove(struct platform_device *pdev)
 217 {
 218         struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev);
 219
 220         uio_unregister_device(priv->uioinfo);
 221         pm_runtime_disable(&pdev->dev);
 222
 223         priv->uioinfo->handler = NULL;
 224         priv->uioinfo->irqcontrol = NULL;
 225
 226         /* kfree uioinfo for OF */
 227         if (pdev->dev.of_node)
 228                 kfree(priv->uioinfo);
 229
 230         kfree(priv);
 231         return 0;
 232 }
 233
 234 static int uio_pdrv_genirq_runtime_nop(struct device *dev)
 235 {
 236         /* Runtime PM callback shared between ->runtime_suspend()
 237          * and ->runtime_resume(). Simply returns success.
 238          *
 239          * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
 240          * are used at open() and release() time. This allows the
 241          * Runtime PM code to turn off power to the device while the
 242          * device is unused, ie before open() and after release().
 243          *
 244          * This Runtime PM callback does not need to save or restore
 245          * any registers since user space is responsbile for hardware
 246          * register reinitialization after open().
 247          */
 248         return 0;
 249 }
 250
 251 static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
 252         .runtime_suspend = uio_pdrv_genirq_runtime_nop,
 253         .runtime_resume = uio_pdrv_genirq_runtime_nop,
 254 };
 255
 256 #ifdef CONFIG_OF
 257 static const struct of_device_id uio_of_genirq_match[] = {
 258         { /* empty for now */ },
 259 };
 260 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
 261 #else
 262 # define uio_of_genirq_match NULL
 263 #endif
 264
 265 static struct platform_driver uio_pdrv_genirq = {
 266         .probe = uio_pdrv_genirq_probe,
 267         .remove = uio_pdrv_genirq_remove,
 268         .driver = {
 269                 .name = DRIVER_NAME,
 270                 .owner = THIS_MODULE,
 271                 .pm = &uio_pdrv_genirq_dev_pm_ops,
 272                 .of_match_table = uio_of_genirq_match,
 273         },
 274 };
 275
 276 module_platform_driver(uio_pdrv_genirq);
 277
 278 MODULE_AUTHOR("Magnus Damm");
 279 MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
 280 MODULE_LICENSE("GPL v2");
 281 MODULE_ALIAS("platform:" DRIVER_NAME);