drivers/uio/uio_dmem_genirq.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * drivers/uio/uio_dmem_genirq.c
   4  *
   5  * Userspace I/O platform driver with generic IRQ handling code.
   6  *
   7  * Copyright (C) 2012 Damian Hobson-Garcia
   8  *
   9  * Based on uio_pdrv_genirq.c by Magnus Damm
  10  */
  11
  12 #include <linux/platform_device.h>
  13 #include <linux/uio_driver.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/bitops.h>
  16 #include <linux/module.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/platform_data/uio_dmem_genirq.h>
  19 #include <linux/stringify.h>
  20 #include <linux/pm_runtime.h>
  21 #include <linux/dma-mapping.h>
  22 #include <linux/slab.h>
  23
  24 #include <linux/of.h>
  25 #include <linux/of_platform.h>
  26 #include <linux/of_address.h>
  27
  28 #define DRIVER_NAME "uio_dmem_genirq"
  29 #define DMEM_MAP_ERROR (~0)
  30
  31 struct uio_dmem_genirq_platdata {
  32         struct uio_info *uioinfo;
  33         spinlock_t lock;
  34         unsigned long flags;
  35         struct platform_device *pdev;
  36         unsigned int dmem_region_start;
  37         unsigned int num_dmem_regions;
  38         void *dmem_region_vaddr[MAX_UIO_MAPS];
  39         struct mutex alloc_lock;
  40         unsigned int refcnt;
  41 };
  42
  43 static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
  44 {
  45         struct uio_dmem_genirq_platdata *priv = info->priv;
  46         struct uio_mem *uiomem;
  47         int ret = 0;
  48         int dmem_region = priv->dmem_region_start;
  49
  50         uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
  51
  52         mutex_lock(&priv->alloc_lock);
  53         while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
  54                 void *addr;
  55                 if (!uiomem->size)
  56                         break;
  57
  58                 addr = dma_alloc_coherent(&priv->pdev->dev, uiomem->size,
  59                                 (dma_addr_t *)&uiomem->addr, GFP_KERNEL);
  60                 if (!addr) {
  61                         uiomem->addr = DMEM_MAP_ERROR;
  62                 }
  63                 priv->dmem_region_vaddr[dmem_region++] = addr;
  64                 ++uiomem;
  65         }
  66         priv->refcnt++;
  67
  68         mutex_unlock(&priv->alloc_lock);
  69         /* Wait until the Runtime PM code has woken up the device */
  70         pm_runtime_get_sync(&priv->pdev->dev);
  71         return ret;
  72 }
  73
  74 static int uio_dmem_genirq_release(struct uio_info *info, struct inode *inode)
  75 {
  76         struct uio_dmem_genirq_platdata *priv = info->priv;
  77         struct uio_mem *uiomem;
  78         int dmem_region = priv->dmem_region_start;
  79
  80         /* Tell the Runtime PM code that the device has become idle */
  81         pm_runtime_put_sync(&priv->pdev->dev);
  82
  83         uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
  84
  85         mutex_lock(&priv->alloc_lock);
  86
  87         priv->refcnt--;
  88         while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
  89                 if (!uiomem->size)
  90                         break;
  91                 if (priv->dmem_region_vaddr[dmem_region]) {
  92                         dma_free_coherent(&priv->pdev->dev, uiomem->size,
  93                                         priv->dmem_region_vaddr[dmem_region],
  94                                         uiomem->addr);
  95                 }
  96                 uiomem->addr = DMEM_MAP_ERROR;
  97                 ++dmem_region;
  98                 ++uiomem;
  99         }
 100
 101         mutex_unlock(&priv->alloc_lock);
 102         return 0;
 103 }
 104
 105 static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info)
 106 {
 107         struct uio_dmem_genirq_platdata *priv = dev_info->priv;
 108
 109         /* Just disable the interrupt in the interrupt controller, and
 110          * remember the state so we can allow user space to enable it later.
 111          */
 112
 113         if (!test_and_set_bit(0, &priv->flags))
 114                 disable_irq_nosync(irq);
 115
 116         return IRQ_HANDLED;
 117 }
 118
 119 static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
 120 {
 121         struct uio_dmem_genirq_platdata *priv = dev_info->priv;
 122         unsigned long flags;
 123
 124         /* Allow user space to enable and disable the interrupt
 125          * in the interrupt controller, but keep track of the
 126          * state to prevent per-irq depth damage.
 127          *
 128          * Serialize this operation to support multiple tasks.
 129          */
 130
 131         spin_lock_irqsave(&priv->lock, flags);
 132         if (irq_on) {
 133                 if (test_and_clear_bit(0, &priv->flags))
 134                         enable_irq(dev_info->irq);
 135         } else {
 136                 if (!test_and_set_bit(0, &priv->flags))
 137                         disable_irq(dev_info->irq);
 138         }
 139         spin_unlock_irqrestore(&priv->lock, flags);
 140
 141         return 0;
 142 }
 143
 144 static int uio_dmem_genirq_probe(struct platform_device *pdev)
 145 {
 146         struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev);
 147         struct uio_info *uioinfo = &pdata->uioinfo;
 148         struct uio_dmem_genirq_platdata *priv;
 149         struct uio_mem *uiomem;
 150         int ret = -EINVAL;
 151         int i;
 152
 153         if (pdev->dev.of_node) {
 154                 int irq;
 155
 156                 /* alloc uioinfo for one device */
 157                 uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
 158                 if (!uioinfo) {
 159                         ret = -ENOMEM;
 160                         dev_err(&pdev->dev, "unable to kmalloc\n");
 161                         goto bad2;
 162                 }
 163                 uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn",
 164                                                pdev->dev.of_node);
 165                 uioinfo->version = "devicetree";
 166
 167                 /* Multiple IRQs are not supported */
 168                 irq = platform_get_irq(pdev, 0);
 169                 if (irq == -ENXIO)
 170                         uioinfo->irq = UIO_IRQ_NONE;
 171                 else
 172                         uioinfo->irq = irq;
 173         }
 174
 175         if (!uioinfo || !uioinfo->name || !uioinfo->version) {
 176                 dev_err(&pdev->dev, "missing platform_data\n");
 177                 goto bad0;
 178         }
 179
 180         if (uioinfo->handler || uioinfo->irqcontrol ||
 181             uioinfo->irq_flags & IRQF_SHARED) {
 182                 dev_err(&pdev->dev, "interrupt configuration error\n");
 183                 goto bad0;
 184         }
 185
 186         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 187         if (!priv) {
 188                 ret = -ENOMEM;
 189                 dev_err(&pdev->dev, "unable to kmalloc\n");
 190                 goto bad0;
 191         }
 192
 193         dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
 194
 195         priv->uioinfo = uioinfo;
 196         spin_lock_init(&priv->lock);
 197         priv->flags = 0; /* interrupt is enabled to begin with */
 198         priv->pdev = pdev;
 199         mutex_init(&priv->alloc_lock);
 200
 201         if (!uioinfo->irq) {
 202                 ret = platform_get_irq(pdev, 0);
 203                 if (ret < 0) {
 204                         dev_err(&pdev->dev, "failed to get IRQ\n");
 205                         goto bad1;
 206                 }
 207                 uioinfo->irq = ret;
 208         }
 209         uiomem = &uioinfo->mem[0];
 210
 211         for (i = 0; i < pdev->num_resources; ++i) {
 212                 struct resource *r = &pdev->resource[i];
 213
 214                 if (r->flags != IORESOURCE_MEM)
 215                         continue;
 216
 217                 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
 218                         dev_warn(&pdev->dev, "device has more than "
 219                                         __stringify(MAX_UIO_MAPS)
 220                                         " I/O memory resources.\n");
 221                         break;
 222                 }
 223
 224                 uiomem->memtype = UIO_MEM_PHYS;
 225                 uiomem->addr = r->start;
 226                 uiomem->size = resource_size(r);
 227                 ++uiomem;
 228         }
 229
 230         priv->dmem_region_start = uiomem - &uioinfo->mem[0];
 231         priv->num_dmem_regions = pdata->num_dynamic_regions;
 232
 233         for (i = 0; i < pdata->num_dynamic_regions; ++i) {
 234                 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
 235                         dev_warn(&pdev->dev, "device has more than "
 236                                         __stringify(MAX_UIO_MAPS)
 237                                         " dynamic and fixed memory regions.\n");
 238                         break;
 239                 }
 240                 uiomem->memtype = UIO_MEM_PHYS;
 241                 uiomem->addr = DMEM_MAP_ERROR;
 242                 uiomem->size = pdata->dynamic_region_sizes[i];
 243                 ++uiomem;
 244         }
 245
 246         while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
 247                 uiomem->size = 0;
 248                 ++uiomem;
 249         }
 250
 251         /* This driver requires no hardware specific kernel code to handle
 252          * interrupts. Instead, the interrupt handler simply disables the
 253          * interrupt in the interrupt controller. User space is responsible
 254          * for performing hardware specific acknowledge and re-enabling of
 255          * the interrupt in the interrupt controller.
 256          *
 257          * Interrupt sharing is not supported.
 258          */
 259
 260         uioinfo->handler = uio_dmem_genirq_handler;
 261         uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
 262         uioinfo->open = uio_dmem_genirq_open;
 263         uioinfo->release = uio_dmem_genirq_release;
 264         uioinfo->priv = priv;
 265
 266         /* Enable Runtime PM for this device:
 267          * The device starts in suspended state to allow the hardware to be
 268          * turned off by default. The Runtime PM bus code should power on the
 269          * hardware and enable clocks at open().
 270          */
 271         pm_runtime_enable(&pdev->dev);
 272
 273         ret = uio_register_device(&pdev->dev, priv->uioinfo);
 274         if (ret) {
 275                 dev_err(&pdev->dev, "unable to register uio device\n");
 276                 pm_runtime_disable(&pdev->dev);
 277                 goto bad1;
 278         }
 279
 280         platform_set_drvdata(pdev, priv);
 281         return 0;
 282  bad1:
 283         kfree(priv);
 284  bad0:
 285         /* kfree uioinfo for OF */
 286         if (pdev->dev.of_node)
 287                 kfree(uioinfo);
 288  bad2:
 289         return ret;
 290 }
 291
 292 static int uio_dmem_genirq_remove(struct platform_device *pdev)
 293 {
 294         struct uio_dmem_genirq_platdata *priv = platform_get_drvdata(pdev);
 295
 296         uio_unregister_device(priv->uioinfo);
 297         pm_runtime_disable(&pdev->dev);
 298
 299         priv->uioinfo->handler = NULL;
 300         priv->uioinfo->irqcontrol = NULL;
 301
 302         /* kfree uioinfo for OF */
 303         if (pdev->dev.of_node)
 304                 kfree(priv->uioinfo);
 305
 306         kfree(priv);
 307         return 0;
 308 }
 309
 310 static int uio_dmem_genirq_runtime_nop(struct device *dev)
 311 {
 312         /* Runtime PM callback shared between ->runtime_suspend()
 313          * and ->runtime_resume(). Simply returns success.
 314          *
 315          * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
 316          * are used at open() and release() time. This allows the
 317          * Runtime PM code to turn off power to the device while the
 318          * device is unused, ie before open() and after release().
 319          *
 320          * This Runtime PM callback does not need to save or restore
 321          * any registers since user space is responsbile for hardware
 322          * register reinitialization after open().
 323          */
 324         return 0;
 325 }
 326
 327 static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
 328         .runtime_suspend = uio_dmem_genirq_runtime_nop,
 329         .runtime_resume = uio_dmem_genirq_runtime_nop,
 330 };
 331
 332 #ifdef CONFIG_OF
 333 static const struct of_device_id uio_of_genirq_match[] = {
 334         { /* empty for now */ },
 335 };
 336 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
 337 #endif
 338
 339 static struct platform_driver uio_dmem_genirq = {
 340         .probe = uio_dmem_genirq_probe,
 341         .remove = uio_dmem_genirq_remove,
 342         .driver = {
 343                 .name = DRIVER_NAME,
 344                 .pm = &uio_dmem_genirq_dev_pm_ops,
 345                 .of_match_table = of_match_ptr(uio_of_genirq_match),
 346         },
 347 };
 348
 349 module_platform_driver(uio_dmem_genirq);
 350
 351 MODULE_AUTHOR("Damian Hobson-Garcia");
 352 MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
 353 MODULE_LICENSE("GPL v2");
 354 MODULE_ALIAS("platform:" DRIVER_NAME);