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 /* Bits in uio_pdrv_genirq_platdata.flags */
  41 enum {
  42         UIO_IRQ_DISABLED = 0,
  43 };
  44
  45 static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode)
  46 {
  47         struct uio_pdrv_genirq_platdata *priv = info->priv;
  48
  49         /* Wait until the Runtime PM code has woken up the device */
  50         pm_runtime_get_sync(&priv->pdev->dev);
  51         return 0;
  52 }
  53
  54 static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode)
  55 {
  56         struct uio_pdrv_genirq_platdata *priv = info->priv;
  57
  58         /* Tell the Runtime PM code that the device has become idle */
  59         pm_runtime_put_sync(&priv->pdev->dev);
  60         return 0;
  61 }
  62
  63 static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info)
  64 {
  65         struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
  66
  67         /* Just disable the interrupt in the interrupt controller, and
  68          * remember the state so we can allow user space to enable it later.
  69          */
  70
  71         spin_lock(&priv->lock);
  72         if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
  73                 disable_irq_nosync(irq);
  74         spin_unlock(&priv->lock);
  75
  76         return IRQ_HANDLED;
  77 }
  78
  79 static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
  80 {
  81         struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
  82         unsigned long flags;
  83
  84         /* Allow user space to enable and disable the interrupt
  85          * in the interrupt controller, but keep track of the
  86          * state to prevent per-irq depth damage.
  87          *
  88          * Serialize this operation to support multiple tasks and concurrency
  89          * with irq handler on SMP systems.
  90          */
  91
  92         spin_lock_irqsave(&priv->lock, flags);
  93         if (irq_on) {
  94                 if (__test_and_clear_bit(UIO_IRQ_DISABLED, &priv->flags))
  95                         enable_irq(dev_info->irq);
  96         } else {
  97                 if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
  98                         disable_irq_nosync(dev_info->irq);
  99         }
 100         spin_unlock_irqrestore(&priv->lock, flags);
 101
 102         return 0;
 103 }
 104
 105 static int uio_pdrv_genirq_probe(struct platform_device *pdev)
 106 {
 107         struct uio_info *uioinfo = dev_get_platdata(&pdev->dev);
 108         struct uio_pdrv_genirq_platdata *priv;
 109         struct uio_mem *uiomem;
 110         int ret = -EINVAL;
 111         int i;
 112
 113         if (pdev->dev.of_node) {
 114                 /* alloc uioinfo for one device */
 115                 uioinfo = devm_kzalloc(&pdev->dev, sizeof(*uioinfo),
 116                                        GFP_KERNEL);
 117                 if (!uioinfo) {
 118                         dev_err(&pdev->dev, "unable to kmalloc\n");
 119                         return -ENOMEM;
 120                 }
 121                 uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn",
 122                                                pdev->dev.of_node);
 123                 uioinfo->version = "devicetree";
 124                 /* Multiple IRQs are not supported */
 125         }
 126
 127         if (!uioinfo || !uioinfo->name || !uioinfo->version) {
 128                 dev_err(&pdev->dev, "missing platform_data\n");
 129                 return ret;
 130         }
 131
 132         if (uioinfo->handler || uioinfo->irqcontrol ||
 133             uioinfo->irq_flags & IRQF_SHARED) {
 134                 dev_err(&pdev->dev, "interrupt configuration error\n");
 135                 return ret;
 136         }
 137
 138         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 139         if (!priv) {
 140                 dev_err(&pdev->dev, "unable to kmalloc\n");
 141                 return -ENOMEM;
 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                 uioinfo->irq = ret;
 152                 if (ret == -ENXIO && pdev->dev.of_node)
 153                         uioinfo->irq = UIO_IRQ_NONE;
 154                 else if (ret < 0) {
 155                         dev_err(&pdev->dev, "failed to get IRQ\n");
 156                         return ret;
 157                 }
 158         }
 159
 160         uiomem = &uioinfo->mem[0];
 161
 162         for (i = 0; i < pdev->num_resources; ++i) {
 163                 struct resource *r = &pdev->resource[i];
 164
 165                 if (r->flags != IORESOURCE_MEM)
 166                         continue;
 167
 168                 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
 169                         dev_warn(&pdev->dev, "device has more than "
 170                                         __stringify(MAX_UIO_MAPS)
 171                                         " I/O memory resources.\n");
 172                         break;
 173                 }
 174
 175                 uiomem->memtype = UIO_MEM_PHYS;
 176                 uiomem->addr = r->start;
 177                 uiomem->size = resource_size(r);
 178                 uiomem->name = r->name;
 179                 ++uiomem;
 180         }
 181
 182         while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
 183                 uiomem->size = 0;
 184                 ++uiomem;
 185         }
 186
 187         /* This driver requires no hardware specific kernel code to handle
 188          * interrupts. Instead, the interrupt handler simply disables the
 189          * interrupt in the interrupt controller. User space is responsible
 190          * for performing hardware specific acknowledge and re-enabling of
 191          * the interrupt in the interrupt controller.
 192          *
 193          * Interrupt sharing is not supported.
 194          */
 195
 196         uioinfo->handler = uio_pdrv_genirq_handler;
 197         uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
 198         uioinfo->open = uio_pdrv_genirq_open;
 199         uioinfo->release = uio_pdrv_genirq_release;
 200         uioinfo->priv = priv;
 201
 202         /* Enable Runtime PM for this device:
 203          * The device starts in suspended state to allow the hardware to be
 204          * turned off by default. The Runtime PM bus code should power on the
 205          * hardware and enable clocks at open().
 206          */
 207         pm_runtime_enable(&pdev->dev);
 208
 209         ret = uio_register_device(&pdev->dev, priv->uioinfo);
 210         if (ret) {
 211                 dev_err(&pdev->dev, "unable to register uio device\n");
 212                 pm_runtime_disable(&pdev->dev);
 213                 return ret;
 214         }
 215
 216         platform_set_drvdata(pdev, priv);
 217         return 0;
 218 }
 219
 220 static int uio_pdrv_genirq_remove(struct platform_device *pdev)
 221 {
 222         struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev);
 223
 224         uio_unregister_device(priv->uioinfo);
 225         pm_runtime_disable(&pdev->dev);
 226
 227         priv->uioinfo->handler = NULL;
 228         priv->uioinfo->irqcontrol = NULL;
 229
 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 struct of_device_id uio_of_genirq_match[] = {
 257         { /* This is filled with module_parm */ },
 258         { /* Sentinel */ },
 259 };
 260 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
 261 module_param_string(of_id, uio_of_genirq_match[0].compatible, 128, 0);
 262 MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio");
 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                 .pm = &uio_pdrv_genirq_dev_pm_ops,
 271                 .of_match_table = of_match_ptr(uio_of_genirq_match),
 272         },
 273 };
 274
 275 module_platform_driver(uio_pdrv_genirq);
 276
 277 MODULE_AUTHOR("Magnus Damm");
 278 MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
 279 MODULE_LICENSE("GPL v2");
 280 MODULE_ALIAS("platform:" DRIVER_NAME);