linux/drivers/uio/uio_pdrv_genirq.c
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   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
  33struct 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 */
  41enum {
  42        UIO_IRQ_DISABLED = 0,
  43};
  44
  45static 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
  54static 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
  63static 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
  79static 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
 105static int uio_pdrv_genirq_probe(struct platform_device *pdev)
 106{
 107        struct uio_info *uioinfo = pdev->dev.platform_data;
 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 = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
 116                if (!uioinfo) {
 117                        ret = -ENOMEM;
 118                        dev_err(&pdev->dev, "unable to kmalloc\n");
 119                        return ret;
 120                }
 121                uioinfo->name = pdev->dev.of_node->name;
 122                uioinfo->version = "devicetree";
 123                /* Multiple IRQs are not supported */
 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                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                        goto bad1;
 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                goto bad2;
 213        }
 214
 215        platform_set_drvdata(pdev, priv);
 216        return 0;
 217 bad2:
 218        pm_runtime_disable(&pdev->dev);
 219 bad1:
 220        kfree(priv);
 221 bad0:
 222        /* kfree uioinfo for OF */
 223        if (pdev->dev.of_node)
 224                kfree(uioinfo);
 225        return ret;
 226}
 227
 228static int uio_pdrv_genirq_remove(struct platform_device *pdev)
 229{
 230        struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev);
 231
 232        uio_unregister_device(priv->uioinfo);
 233        pm_runtime_disable(&pdev->dev);
 234
 235        priv->uioinfo->handler = NULL;
 236        priv->uioinfo->irqcontrol = NULL;
 237
 238        /* kfree uioinfo for OF */
 239        if (pdev->dev.of_node)
 240                kfree(priv->uioinfo);
 241
 242        kfree(priv);
 243        return 0;
 244}
 245
 246static int uio_pdrv_genirq_runtime_nop(struct device *dev)
 247{
 248        /* Runtime PM callback shared between ->runtime_suspend()
 249         * and ->runtime_resume(). Simply returns success.
 250         *
 251         * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
 252         * are used at open() and release() time. This allows the
 253         * Runtime PM code to turn off power to the device while the
 254         * device is unused, ie before open() and after release().
 255         *
 256         * This Runtime PM callback does not need to save or restore
 257         * any registers since user space is responsbile for hardware
 258         * register reinitialization after open().
 259         */
 260        return 0;
 261}
 262
 263static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
 264        .runtime_suspend = uio_pdrv_genirq_runtime_nop,
 265        .runtime_resume = uio_pdrv_genirq_runtime_nop,
 266};
 267
 268#ifdef CONFIG_OF
 269static struct of_device_id uio_of_genirq_match[] = {
 270        { /* This is filled with module_parm */ },
 271        { /* Sentinel */ },
 272};
 273MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
 274module_param_string(of_id, uio_of_genirq_match[0].compatible, 128, 0);
 275MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio");
 276#endif
 277
 278static struct platform_driver uio_pdrv_genirq = {
 279        .probe = uio_pdrv_genirq_probe,
 280        .remove = uio_pdrv_genirq_remove,
 281        .driver = {
 282                .name = DRIVER_NAME,
 283                .owner = THIS_MODULE,
 284                .pm = &uio_pdrv_genirq_dev_pm_ops,
 285                .of_match_table = of_match_ptr(uio_of_genirq_match),
 286        },
 287};
 288
 289module_platform_driver(uio_pdrv_genirq);
 290
 291MODULE_AUTHOR("Magnus Damm");
 292MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
 293MODULE_LICENSE("GPL v2");
 294MODULE_ALIAS("platform:" DRIVER_NAME);
 295
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