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                 spin_unlock_irqrestore(&priv->lock, flags);
 139         } else {
 140                 if (!test_and_set_bit(0, &priv->flags)) {
 141                         spin_unlock_irqrestore(&priv->lock, flags);
 142                         disable_irq(dev_info->irq);
 143                 }
 144         }
 145
 146         return 0;
 147 }
 148
 149 static int uio_dmem_genirq_probe(struct platform_device *pdev)
 150 {
 151         struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev);
 152         struct uio_info *uioinfo = &pdata->uioinfo;
 153         struct uio_dmem_genirq_platdata *priv;
 154         struct uio_mem *uiomem;
 155         int ret = -EINVAL;
 156         int i;
 157
 158         if (pdev->dev.of_node) {
 159                 int irq;
 160
 161                 /* alloc uioinfo for one device */
 162                 uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
 163                 if (!uioinfo) {
 164                         ret = -ENOMEM;
 165                         dev_err(&pdev->dev, "unable to kmalloc\n");
 166                         goto bad2;
 167                 }
 168                 uioinfo->name = pdev->dev.of_node->name;
 169                 uioinfo->version = "devicetree";
 170
 171                 /* Multiple IRQs are not supported */
 172                 irq = platform_get_irq(pdev, 0);
 173                 if (irq == -ENXIO)
 174                         uioinfo->irq = UIO_IRQ_NONE;
 175                 else
 176                         uioinfo->irq = irq;
 177         }
 178
 179         if (!uioinfo || !uioinfo->name || !uioinfo->version) {
 180                 dev_err(&pdev->dev, "missing platform_data\n");
 181                 goto bad0;
 182         }
 183
 184         if (uioinfo->handler || uioinfo->irqcontrol ||
 185             uioinfo->irq_flags & IRQF_SHARED) {
 186                 dev_err(&pdev->dev, "interrupt configuration error\n");
 187                 goto bad0;
 188         }
 189
 190         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 191         if (!priv) {
 192                 ret = -ENOMEM;
 193                 dev_err(&pdev->dev, "unable to kmalloc\n");
 194                 goto bad0;
 195         }
 196
 197         dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
 198
 199         priv->uioinfo = uioinfo;
 200         spin_lock_init(&priv->lock);
 201         priv->flags = 0; /* interrupt is enabled to begin with */
 202         priv->pdev = pdev;
 203         mutex_init(&priv->alloc_lock);
 204
 205         if (!uioinfo->irq) {
 206                 ret = platform_get_irq(pdev, 0);
 207                 if (ret < 0) {
 208                         dev_err(&pdev->dev, "failed to get IRQ\n");
 209                         goto bad1;
 210                 }
 211                 uioinfo->irq = ret;
 212         }
 213         uiomem = &uioinfo->mem[0];
 214
 215         for (i = 0; i < pdev->num_resources; ++i) {
 216                 struct resource *r = &pdev->resource[i];
 217
 218                 if (r->flags != IORESOURCE_MEM)
 219                         continue;
 220
 221                 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
 222                         dev_warn(&pdev->dev, "device has more than "
 223                                         __stringify(MAX_UIO_MAPS)
 224                                         " I/O memory resources.\n");
 225                         break;
 226                 }
 227
 228                 uiomem->memtype = UIO_MEM_PHYS;
 229                 uiomem->addr = r->start;
 230                 uiomem->size = resource_size(r);
 231                 ++uiomem;
 232         }
 233
 234         priv->dmem_region_start = uiomem - &uioinfo->mem[0];
 235         priv->num_dmem_regions = pdata->num_dynamic_regions;
 236
 237         for (i = 0; i < pdata->num_dynamic_regions; ++i) {
 238                 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
 239                         dev_warn(&pdev->dev, "device has more than "
 240                                         __stringify(MAX_UIO_MAPS)
 241                                         " dynamic and fixed memory regions.\n");
 242                         break;
 243                 }
 244                 uiomem->memtype = UIO_MEM_PHYS;
 245                 uiomem->addr = DMEM_MAP_ERROR;
 246                 uiomem->size = pdata->dynamic_region_sizes[i];
 247                 ++uiomem;
 248         }
 249
 250         while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
 251                 uiomem->size = 0;
 252                 ++uiomem;
 253         }
 254
 255         /* This driver requires no hardware specific kernel code to handle
 256          * interrupts. Instead, the interrupt handler simply disables the
 257          * interrupt in the interrupt controller. User space is responsible
 258          * for performing hardware specific acknowledge and re-enabling of
 259          * the interrupt in the interrupt controller.
 260          *
 261          * Interrupt sharing is not supported.
 262          */
 263
 264         uioinfo->handler = uio_dmem_genirq_handler;
 265         uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
 266         uioinfo->open = uio_dmem_genirq_open;
 267         uioinfo->release = uio_dmem_genirq_release;
 268         uioinfo->priv = priv;
 269
 270         /* Enable Runtime PM for this device:
 271          * The device starts in suspended state to allow the hardware to be
 272          * turned off by default. The Runtime PM bus code should power on the
 273          * hardware and enable clocks at open().
 274          */
 275         pm_runtime_enable(&pdev->dev);
 276
 277         ret = uio_register_device(&pdev->dev, priv->uioinfo);
 278         if (ret) {
 279                 dev_err(&pdev->dev, "unable to register uio device\n");
 280                 pm_runtime_disable(&pdev->dev);
 281                 goto bad1;
 282         }
 283
 284         platform_set_drvdata(pdev, priv);
 285         return 0;
 286  bad1:
 287         kfree(priv);
 288  bad0:
 289         /* kfree uioinfo for OF */
 290         if (pdev->dev.of_node)
 291                 kfree(uioinfo);
 292  bad2:
 293         return ret;
 294 }
 295
 296 static int uio_dmem_genirq_remove(struct platform_device *pdev)
 297 {
 298         struct uio_dmem_genirq_platdata *priv = platform_get_drvdata(pdev);
 299
 300         uio_unregister_device(priv->uioinfo);
 301         pm_runtime_disable(&pdev->dev);
 302
 303         priv->uioinfo->handler = NULL;
 304         priv->uioinfo->irqcontrol = NULL;
 305
 306         /* kfree uioinfo for OF */
 307         if (pdev->dev.of_node)
 308                 kfree(priv->uioinfo);
 309
 310         kfree(priv);
 311         return 0;
 312 }
 313
 314 static int uio_dmem_genirq_runtime_nop(struct device *dev)
 315 {
 316         /* Runtime PM callback shared between ->runtime_suspend()
 317          * and ->runtime_resume(). Simply returns success.
 318          *
 319          * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
 320          * are used at open() and release() time. This allows the
 321          * Runtime PM code to turn off power to the device while the
 322          * device is unused, ie before open() and after release().
 323          *
 324          * This Runtime PM callback does not need to save or restore
 325          * any registers since user space is responsbile for hardware
 326          * register reinitialization after open().
 327          */
 328         return 0;
 329 }
 330
 331 static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
 332         .runtime_suspend = uio_dmem_genirq_runtime_nop,
 333         .runtime_resume = uio_dmem_genirq_runtime_nop,
 334 };
 335
 336 #ifdef CONFIG_OF
 337 static const struct of_device_id uio_of_genirq_match[] = {
 338         { /* empty for now */ },
 339 };
 340 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
 341 #endif
 342
 343 static struct platform_driver uio_dmem_genirq = {
 344         .probe = uio_dmem_genirq_probe,
 345         .remove = uio_dmem_genirq_remove,
 346         .driver = {
 347                 .name = DRIVER_NAME,
 348                 .pm = &uio_dmem_genirq_dev_pm_ops,
 349                 .of_match_table = of_match_ptr(uio_of_genirq_match),
 350         },
 351 };
 352
 353 module_platform_driver(uio_dmem_genirq);
 354
 355 MODULE_AUTHOR("Damian Hobson-Garcia");
 356 MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
 357 MODULE_LICENSE("GPL v2");
 358 MODULE_ALIAS("platform:" DRIVER_NAME);