drivers/uio/uio_dmem_genirq.c

   1 /*
   2  * drivers/uio/uio_dmem_genirq.c
   3  *
   4  * Userspace I/O platform driver with generic IRQ handling code.
   5  *
   6  * Copyright (C) 2012 Damian Hobson-Garcia
   7  *
   8  * Based on uio_pdrv_genirq.c by Magnus Damm
   9  *
  10  * This program is free software; you can redistribute it and/or modify it
  11  * under the terms of the GNU General Public License version 2 as published by
  12  * the Free Software Foundation.
  13  */
  14
  15 #include <linux/platform_device.h>
  16 #include <linux/uio_driver.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/bitops.h>
  19 #include <linux/module.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/platform_data/uio_dmem_genirq.h>
  22 #include <linux/stringify.h>
  23 #include <linux/pm_runtime.h>
  24 #include <linux/dma-mapping.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_dmem_genirq"
  32 #define DMEM_MAP_ERROR (~0)
  33
  34 struct uio_dmem_genirq_platdata {
  35         struct uio_info *uioinfo;
  36         spinlock_t lock;
  37         unsigned long flags;
  38         struct platform_device *pdev;
  39         unsigned int dmem_region_start;
  40         unsigned int num_dmem_regions;
  41         void *dmem_region_vaddr[MAX_UIO_MAPS];
  42         struct mutex alloc_lock;
  43         unsigned int refcnt;
  44 };
  45
  46 static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
  47 {
  48         struct uio_dmem_genirq_platdata *priv = info->priv;
  49         struct uio_mem *uiomem;
  50         int ret = 0;
  51         int dmem_region = priv->dmem_region_start;
  52
  53         uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
  54
  55         mutex_lock(&priv->alloc_lock);
  56         while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
  57                 void *addr;
  58                 if (!uiomem->size)
  59                         break;
  60
  61                 addr = dma_alloc_coherent(&priv->pdev->dev, uiomem->size,
  62                                 (dma_addr_t *)&uiomem->addr, GFP_KERNEL);
  63                 if (!addr) {
  64                         uiomem->addr = DMEM_MAP_ERROR;
  65                 }
  66                 priv->dmem_region_vaddr[dmem_region++] = addr;
  67                 ++uiomem;
  68         }
  69         priv->refcnt++;
  70
  71         mutex_unlock(&priv->alloc_lock);
  72         /* Wait until the Runtime PM code has woken up the device */
  73         pm_runtime_get_sync(&priv->pdev->dev);
  74         return ret;
  75 }
  76
  77 static int uio_dmem_genirq_release(struct uio_info *info, struct inode *inode)
  78 {
  79         struct uio_dmem_genirq_platdata *priv = info->priv;
  80         struct uio_mem *uiomem;
  81         int dmem_region = priv->dmem_region_start;
  82
  83         /* Tell the Runtime PM code that the device has become idle */
  84         pm_runtime_put_sync(&priv->pdev->dev);
  85
  86         uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
  87
  88         mutex_lock(&priv->alloc_lock);
  89
  90         priv->refcnt--;
  91         while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
  92                 if (!uiomem->size)
  93                         break;
  94                 if (priv->dmem_region_vaddr[dmem_region]) {
  95                         dma_free_coherent(&priv->pdev->dev, uiomem->size,
  96                                         priv->dmem_region_vaddr[dmem_region],
  97                                         uiomem->addr);
  98                 }
  99                 uiomem->addr = DMEM_MAP_ERROR;
 100                 ++dmem_region;
 101                 ++uiomem;
 102         }
 103
 104         mutex_unlock(&priv->alloc_lock);
 105         return 0;
 106 }
 107
 108 static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info)
 109 {
 110         struct uio_dmem_genirq_platdata *priv = dev_info->priv;
 111
 112         /* Just disable the interrupt in the interrupt controller, and
 113          * remember the state so we can allow user space to enable it later.
 114          */
 115
 116         if (!test_and_set_bit(0, &priv->flags))
 117                 disable_irq_nosync(irq);
 118
 119         return IRQ_HANDLED;
 120 }
 121
 122 static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
 123 {
 124         struct uio_dmem_genirq_platdata *priv = dev_info->priv;
 125         unsigned long flags;
 126
 127         /* Allow user space to enable and disable the interrupt
 128          * in the interrupt controller, but keep track of the
 129          * state to prevent per-irq depth damage.
 130          *
 131          * Serialize this operation to support multiple tasks.
 132          */
 133
 134         spin_lock_irqsave(&priv->lock, flags);
 135         if (irq_on) {
 136                 if (test_and_clear_bit(0, &priv->flags))
 137                         enable_irq(dev_info->irq);
 138         } else {
 139                 if (!test_and_set_bit(0, &priv->flags))
 140                         disable_irq(dev_info->irq);
 141         }
 142         spin_unlock_irqrestore(&priv->lock, flags);
 143
 144         return 0;
 145 }
 146
 147 static int uio_dmem_genirq_probe(struct platform_device *pdev)
 148 {
 149         struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev);
 150         struct uio_info *uioinfo = &pdata->uioinfo;
 151         struct uio_dmem_genirq_platdata *priv;
 152         struct uio_mem *uiomem;
 153         int ret = -EINVAL;
 154         int i;
 155
 156         if (pdev->dev.of_node) {
 157                 int irq;
 158
 159                 /* alloc uioinfo for one device */
 160                 uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
 161                 if (!uioinfo) {
 162                         ret = -ENOMEM;
 163                         dev_err(&pdev->dev, "unable to kmalloc\n");
 164                         goto bad2;
 165                 }
 166                 uioinfo->name = pdev->dev.of_node->name;
 167                 uioinfo->version = "devicetree";
 168
 169                 /* Multiple IRQs are not supported */
 170                 irq = platform_get_irq(pdev, 0);
 171                 if (irq == -ENXIO)
 172                         uioinfo->irq = UIO_IRQ_NONE;
 173                 else
 174                         uioinfo->irq = irq;
 175         }
 176
 177         if (!uioinfo || !uioinfo->name || !uioinfo->version) {
 178                 dev_err(&pdev->dev, "missing platform_data\n");
 179                 goto bad0;
 180         }
 181
 182         if (uioinfo->handler || uioinfo->irqcontrol ||
 183             uioinfo->irq_flags & IRQF_SHARED) {
 184                 dev_err(&pdev->dev, "interrupt configuration error\n");
 185                 goto bad0;
 186         }
 187
 188         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 189         if (!priv) {
 190                 ret = -ENOMEM;
 191                 dev_err(&pdev->dev, "unable to kmalloc\n");
 192                 goto bad0;
 193         }
 194
 195         dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
 196
 197         priv->uioinfo = uioinfo;
 198         spin_lock_init(&priv->lock);
 199         priv->flags = 0; /* interrupt is enabled to begin with */
 200         priv->pdev = pdev;
 201         mutex_init(&priv->alloc_lock);
 202
 203         if (!uioinfo->irq) {
 204                 ret = platform_get_irq(pdev, 0);
 205                 if (ret < 0) {
 206                         dev_err(&pdev->dev, "failed to get IRQ\n");
 207                         goto bad1;
 208                 }
 209                 uioinfo->irq = ret;
 210         }
 211         uiomem = &uioinfo->mem[0];
 212
 213         for (i = 0; i < pdev->num_resources; ++i) {
 214                 struct resource *r = &pdev->resource[i];
 215
 216                 if (r->flags != IORESOURCE_MEM)
 217                         continue;
 218
 219                 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
 220                         dev_warn(&pdev->dev, "device has more than "
 221                                         __stringify(MAX_UIO_MAPS)
 222                                         " I/O memory resources.\n");
 223                         break;
 224                 }
 225
 226                 uiomem->memtype = UIO_MEM_PHYS;
 227                 uiomem->addr = r->start;
 228                 uiomem->size = resource_size(r);
 229                 ++uiomem;
 230         }
 231
 232         priv->dmem_region_start = uiomem - &uioinfo->mem[0];
 233         priv->num_dmem_regions = pdata->num_dynamic_regions;
 234
 235         for (i = 0; i < pdata->num_dynamic_regions; ++i) {
 236                 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
 237                         dev_warn(&pdev->dev, "device has more than "
 238                                         __stringify(MAX_UIO_MAPS)
 239                                         " dynamic and fixed memory regions.\n");
 240                         break;
 241                 }
 242                 uiomem->memtype = UIO_MEM_PHYS;
 243                 uiomem->addr = DMEM_MAP_ERROR;
 244                 uiomem->size = pdata->dynamic_region_sizes[i];
 245                 ++uiomem;
 246         }
 247
 248         while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
 249                 uiomem->size = 0;
 250                 ++uiomem;
 251         }
 252
 253         /* This driver requires no hardware specific kernel code to handle
 254          * interrupts. Instead, the interrupt handler simply disables the
 255          * interrupt in the interrupt controller. User space is responsible
 256          * for performing hardware specific acknowledge and re-enabling of
 257          * the interrupt in the interrupt controller.
 258          *
 259          * Interrupt sharing is not supported.
 260          */
 261
 262         uioinfo->handler = uio_dmem_genirq_handler;
 263         uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
 264         uioinfo->open = uio_dmem_genirq_open;
 265         uioinfo->release = uio_dmem_genirq_release;
 266         uioinfo->priv = priv;
 267
 268         /* Enable Runtime PM for this device:
 269          * The device starts in suspended state to allow the hardware to be
 270          * turned off by default. The Runtime PM bus code should power on the
 271          * hardware and enable clocks at open().
 272          */
 273         pm_runtime_enable(&pdev->dev);
 274
 275         ret = uio_register_device(&pdev->dev, priv->uioinfo);
 276         if (ret) {
 277                 dev_err(&pdev->dev, "unable to register uio device\n");
 278                 pm_runtime_disable(&pdev->dev);
 279                 goto bad1;
 280         }
 281
 282         platform_set_drvdata(pdev, priv);
 283         return 0;
 284  bad1:
 285         kfree(priv);
 286  bad0:
 287         /* kfree uioinfo for OF */
 288         if (pdev->dev.of_node)
 289                 kfree(uioinfo);
 290  bad2:
 291         return ret;
 292 }
 293
 294 static int uio_dmem_genirq_remove(struct platform_device *pdev)
 295 {
 296         struct uio_dmem_genirq_platdata *priv = platform_get_drvdata(pdev);
 297
 298         uio_unregister_device(priv->uioinfo);
 299         pm_runtime_disable(&pdev->dev);
 300
 301         priv->uioinfo->handler = NULL;
 302         priv->uioinfo->irqcontrol = NULL;
 303
 304         /* kfree uioinfo for OF */
 305         if (pdev->dev.of_node)
 306                 kfree(priv->uioinfo);
 307
 308         kfree(priv);
 309         return 0;
 310 }
 311
 312 static int uio_dmem_genirq_runtime_nop(struct device *dev)
 313 {
 314         /* Runtime PM callback shared between ->runtime_suspend()
 315          * and ->runtime_resume(). Simply returns success.
 316          *
 317          * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
 318          * are used at open() and release() time. This allows the
 319          * Runtime PM code to turn off power to the device while the
 320          * device is unused, ie before open() and after release().
 321          *
 322          * This Runtime PM callback does not need to save or restore
 323          * any registers since user space is responsbile for hardware
 324          * register reinitialization after open().
 325          */
 326         return 0;
 327 }
 328
 329 static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
 330         .runtime_suspend = uio_dmem_genirq_runtime_nop,
 331         .runtime_resume = uio_dmem_genirq_runtime_nop,
 332 };
 333
 334 #ifdef CONFIG_OF
 335 static const struct of_device_id uio_of_genirq_match[] = {
 336         { /* empty for now */ },
 337 };
 338 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
 339 #endif
 340
 341 static struct platform_driver uio_dmem_genirq = {
 342         .probe = uio_dmem_genirq_probe,
 343         .remove = uio_dmem_genirq_remove,
 344         .driver = {
 345                 .name = DRIVER_NAME,
 346                 .pm = &uio_dmem_genirq_dev_pm_ops,
 347                 .of_match_table = of_match_ptr(uio_of_genirq_match),
 348         },
 349 };
 350
 351 module_platform_driver(uio_dmem_genirq);
 352
 353 MODULE_AUTHOR("Damian Hobson-Garcia");
 354 MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
 355 MODULE_LICENSE("GPL v2");
 356 MODULE_ALIAS("platform:" DRIVER_NAME);