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
  40static 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
  49static 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
  58static 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
  72static 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
  97static 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 (pdev->dev.of_node) {
 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->name = r->name;
 176                ++uiomem;
 177        }
 178
 179        while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
 180                uiomem->size = 0;
 181                ++uiomem;
 182        }
 183
 184        /* This driver requires no hardware specific kernel code to handle
 185         * interrupts. Instead, the interrupt handler simply disables the
 186         * interrupt in the interrupt controller. User space is responsible
 187         * for performing hardware specific acknowledge and re-enabling of
 188         * the interrupt in the interrupt controller.
 189         *
 190         * Interrupt sharing is not supported.
 191         */
 192
 193        uioinfo->handler = uio_pdrv_genirq_handler;
 194        uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
 195        uioinfo->open = uio_pdrv_genirq_open;
 196        uioinfo->release = uio_pdrv_genirq_release;
 197        uioinfo->priv = priv;
 198
 199        /* Enable Runtime PM for this device:
 200         * The device starts in suspended state to allow the hardware to be
 201         * turned off by default. The Runtime PM bus code should power on the
 202         * hardware and enable clocks at open().
 203         */
 204        pm_runtime_enable(&pdev->dev);
 205
 206        ret = uio_register_device(&pdev->dev, priv->uioinfo);
 207        if (ret) {
 208                dev_err(&pdev->dev, "unable to register uio device\n");
 209                goto bad1;
 210        }
 211
 212        platform_set_drvdata(pdev, priv);
 213        return 0;
 214 bad1:
 215        kfree(priv);
 216        pm_runtime_disable(&pdev->dev);
 217 bad0:
 218        /* kfree uioinfo for OF */
 219        if (pdev->dev.of_node)
 220                kfree(uioinfo);
 221 bad2:
 222        return ret;
 223}
 224
 225static int uio_pdrv_genirq_remove(struct platform_device *pdev)
 226{
 227        struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev);
 228
 229        uio_unregister_device(priv->uioinfo);
 230        pm_runtime_disable(&pdev->dev);
 231
 232        priv->uioinfo->handler = NULL;
 233        priv->uioinfo->irqcontrol = NULL;
 234
 235        /* kfree uioinfo for OF */
 236        if (pdev->dev.of_node)
 237                kfree(priv->uioinfo);
 238
 239        kfree(priv);
 240        return 0;
 241}
 242
 243static int uio_pdrv_genirq_runtime_nop(struct device *dev)
 244{
 245        /* Runtime PM callback shared between ->runtime_suspend()
 246         * and ->runtime_resume(). Simply returns success.
 247         *
 248         * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
 249         * are used at open() and release() time. This allows the
 250         * Runtime PM code to turn off power to the device while the
 251         * device is unused, ie before open() and after release().
 252         *
 253         * This Runtime PM callback does not need to save or restore
 254         * any registers since user space is responsbile for hardware
 255         * register reinitialization after open().
 256         */
 257        return 0;
 258}
 259
 260static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
 261        .runtime_suspend = uio_pdrv_genirq_runtime_nop,
 262        .runtime_resume = uio_pdrv_genirq_runtime_nop,
 263};
 264
 265#ifdef CONFIG_OF
 266static const struct of_device_id uio_of_genirq_match[] = {
 267        { /* empty for now */ },
 268};
 269MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
 270#else
 271# define uio_of_genirq_match NULL
 272#endif
 273
 274static struct platform_driver uio_pdrv_genirq = {
 275        .probe = uio_pdrv_genirq_probe,
 276        .remove = uio_pdrv_genirq_remove,
 277        .driver = {
 278                .name = DRIVER_NAME,
 279                .owner = THIS_MODULE,
 280                .pm = &uio_pdrv_genirq_dev_pm_ops,
 281                .of_match_table = uio_of_genirq_match,
 282        },
 283};
 284
 285module_platform_driver(uio_pdrv_genirq);
 286
 287MODULE_AUTHOR("Magnus Damm");
 288MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
 289MODULE_LICENSE("GPL v2");
 290MODULE_ALIAS("platform:" DRIVER_NAME);
 291
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