drivers/uio/uio_pdrv_genirq.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * drivers/uio/uio_pdrv_genirq.c
   4  *
   5  * Userspace I/O platform driver with generic IRQ handling code.
   6  *
   7  * Copyright (C) 2008 Magnus Damm
   8  *
   9  * Based on uio_pdrv.c by Uwe Kleine-Koenig,
  10  * Copyright (C) 2008 by Digi International Inc.
  11  * All rights reserved.
  12  */
  13
  14 #include <linux/platform_device.h>
  15 #include <linux/uio_driver.h>
  16 #include <linux/spinlock.h>
  17 #include <linux/bitops.h>
  18 #include <linux/module.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/stringify.h>
  21 #include <linux/pm_runtime.h>
  22 #include <linux/slab.h>
  23 #include <linux/irq.h>
  24
  25 #include <linux/of.h>
  26 #include <linux/mod_devicetable.h>
  27 #include <linux/property.h>
  28
  29 #define DRIVER_NAME "uio_pdrv_genirq"
  30
  31 struct uio_pdrv_genirq_platdata {
  32         struct uio_info *uioinfo;
  33         spinlock_t lock;
  34         unsigned long flags;
  35         struct platform_device *pdev;
  36 };
  37
  38 /* Bits in uio_pdrv_genirq_platdata.flags */
  39 enum {
  40         UIO_IRQ_DISABLED = 0,
  41 };
  42
  43 static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode)
  44 {
  45         struct uio_pdrv_genirq_platdata *priv = info->priv;
  46
  47         /* Wait until the Runtime PM code has woken up the device */
  48         pm_runtime_get_sync(&priv->pdev->dev);
  49         return 0;
  50 }
  51
  52 static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode)
  53 {
  54         struct uio_pdrv_genirq_platdata *priv = info->priv;
  55
  56         /* Tell the Runtime PM code that the device has become idle */
  57         pm_runtime_put_sync(&priv->pdev->dev);
  58         return 0;
  59 }
  60
  61 static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info)
  62 {
  63         struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
  64
  65         /* Just disable the interrupt in the interrupt controller, and
  66          * remember the state so we can allow user space to enable it later.
  67          */
  68
  69         spin_lock(&priv->lock);
  70         if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
  71                 disable_irq_nosync(irq);
  72         spin_unlock(&priv->lock);
  73
  74         return IRQ_HANDLED;
  75 }
  76
  77 static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
  78 {
  79         struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
  80         unsigned long flags;
  81
  82         /* Allow user space to enable and disable the interrupt
  83          * in the interrupt controller, but keep track of the
  84          * state to prevent per-irq depth damage.
  85          *
  86          * Serialize this operation to support multiple tasks and concurrency
  87          * with irq handler on SMP systems.
  88          */
  89
  90         spin_lock_irqsave(&priv->lock, flags);
  91         if (irq_on) {
  92                 if (__test_and_clear_bit(UIO_IRQ_DISABLED, &priv->flags))
  93                         enable_irq(dev_info->irq);
  94         } else {
  95                 if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
  96                         disable_irq_nosync(dev_info->irq);
  97         }
  98         spin_unlock_irqrestore(&priv->lock, flags);
  99
 100         return 0;
 101 }
 102
 103 static void uio_pdrv_genirq_cleanup(void *data)
 104 {
 105         struct device *dev = data;
 106
 107         pm_runtime_disable(dev);
 108 }
 109
 110 static int uio_pdrv_genirq_probe(struct platform_device *pdev)
 111 {
 112         struct uio_info *uioinfo = dev_get_platdata(&pdev->dev);
 113         struct fwnode_handle *node = dev_fwnode(&pdev->dev);
 114         struct uio_pdrv_genirq_platdata *priv;
 115         struct uio_mem *uiomem;
 116         int ret = -EINVAL;
 117         int i;
 118
 119         if (node) {
 120                 const char *name;
 121
 122                 /* alloc uioinfo for one device */
 123                 uioinfo = devm_kzalloc(&pdev->dev, sizeof(*uioinfo),
 124                                        GFP_KERNEL);
 125                 if (!uioinfo) {
 126                         dev_err(&pdev->dev, "unable to kmalloc\n");
 127                         return -ENOMEM;
 128                 }
 129
 130                 if (!device_property_read_string(&pdev->dev, "linux,uio-name", &name))
 131                         uioinfo->name = devm_kstrdup(&pdev->dev, name, GFP_KERNEL);
 132                 else
 133                         uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
 134                                                        "%pfwP", node);
 135
 136                 uioinfo->version = "devicetree";
 137                 /* Multiple IRQs are not supported */
 138         }
 139
 140         if (!uioinfo || !uioinfo->name || !uioinfo->version) {
 141                 dev_err(&pdev->dev, "missing platform_data\n");
 142                 return ret;
 143         }
 144
 145         if (uioinfo->handler || uioinfo->irqcontrol ||
 146             uioinfo->irq_flags & IRQF_SHARED) {
 147                 dev_err(&pdev->dev, "interrupt configuration error\n");
 148                 return ret;
 149         }
 150
 151         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 152         if (!priv) {
 153                 dev_err(&pdev->dev, "unable to kmalloc\n");
 154                 return -ENOMEM;
 155         }
 156
 157         priv->uioinfo = uioinfo;
 158         spin_lock_init(&priv->lock);
 159         priv->flags = 0; /* interrupt is enabled to begin with */
 160         priv->pdev = pdev;
 161
 162         if (!uioinfo->irq) {
 163                 ret = platform_get_irq_optional(pdev, 0);
 164                 uioinfo->irq = ret;
 165                 if (ret == -ENXIO)
 166                         uioinfo->irq = UIO_IRQ_NONE;
 167                 else if (ret == -EPROBE_DEFER)
 168                         return ret;
 169                 else if (ret < 0) {
 170                         dev_err(&pdev->dev, "failed to get IRQ\n");
 171                         return ret;
 172                 }
 173         }
 174
 175         if (uioinfo->irq) {
 176                 /*
 177                  * If a level interrupt, dont do lazy disable. Otherwise the
 178                  * irq will fire again since clearing of the actual cause, on
 179                  * device level, is done in userspace
 180                  * irqd_is_level_type() isn't used since isn't valid until
 181                  * irq is configured.
 182                  */
 183                 if (irq_get_trigger_type(uioinfo->irq) & IRQ_TYPE_LEVEL_MASK) {
 184                         dev_dbg(&pdev->dev, "disable lazy unmask\n");
 185                         irq_set_status_flags(uioinfo->irq, IRQ_DISABLE_UNLAZY);
 186                 }
 187         }
 188
 189         uiomem = &uioinfo->mem[0];
 190
 191         for (i = 0; i < pdev->num_resources; ++i) {
 192                 struct resource *r = &pdev->resource[i];
 193
 194                 if (r->flags != IORESOURCE_MEM)
 195                         continue;
 196
 197                 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
 198                         dev_warn(&pdev->dev, "device has more than "
 199                                         __stringify(MAX_UIO_MAPS)
 200                                         " I/O memory resources.\n");
 201                         break;
 202                 }
 203
 204                 uiomem->memtype = UIO_MEM_PHYS;
 205                 uiomem->addr = r->start & PAGE_MASK;
 206                 uiomem->offs = r->start & ~PAGE_MASK;
 207                 uiomem->size = (uiomem->offs + resource_size(r)
 208                                 + PAGE_SIZE - 1) & PAGE_MASK;
 209                 uiomem->name = r->name;
 210                 ++uiomem;
 211         }
 212
 213         while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
 214                 uiomem->size = 0;
 215                 ++uiomem;
 216         }
 217
 218         /* This driver requires no hardware specific kernel code to handle
 219          * interrupts. Instead, the interrupt handler simply disables the
 220          * interrupt in the interrupt controller. User space is responsible
 221          * for performing hardware specific acknowledge and re-enabling of
 222          * the interrupt in the interrupt controller.
 223          *
 224          * Interrupt sharing is not supported.
 225          */
 226
 227         uioinfo->handler = uio_pdrv_genirq_handler;
 228         uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
 229         uioinfo->open = uio_pdrv_genirq_open;
 230         uioinfo->release = uio_pdrv_genirq_release;
 231         uioinfo->priv = priv;
 232
 233         /* Enable Runtime PM for this device:
 234          * The device starts in suspended state to allow the hardware to be
 235          * turned off by default. The Runtime PM bus code should power on the
 236          * hardware and enable clocks at open().
 237          */
 238         pm_runtime_enable(&pdev->dev);
 239
 240         ret = devm_add_action_or_reset(&pdev->dev, uio_pdrv_genirq_cleanup,
 241                                        &pdev->dev);
 242         if (ret)
 243                 return ret;
 244
 245         ret = devm_uio_register_device(&pdev->dev, priv->uioinfo);
 246         if (ret)
 247                 dev_err(&pdev->dev, "unable to register uio device\n");
 248
 249         return ret;
 250 }
 251
 252 static int uio_pdrv_genirq_runtime_nop(struct device *dev)
 253 {
 254         /* Runtime PM callback shared between ->runtime_suspend()
 255          * and ->runtime_resume(). Simply returns success.
 256          *
 257          * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
 258          * are used at open() and release() time. This allows the
 259          * Runtime PM code to turn off power to the device while the
 260          * device is unused, ie before open() and after release().
 261          *
 262          * This Runtime PM callback does not need to save or restore
 263          * any registers since user space is responsbile for hardware
 264          * register reinitialization after open().
 265          */
 266         return 0;
 267 }
 268
 269 static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
 270         .runtime_suspend = uio_pdrv_genirq_runtime_nop,
 271         .runtime_resume = uio_pdrv_genirq_runtime_nop,
 272 };
 273
 274 #ifdef CONFIG_OF
 275 static struct of_device_id uio_of_genirq_match[] = {
 276         { /* This is filled with module_parm */ },
 277         { /* Sentinel */ },
 278 };
 279 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
 280 module_param_string(of_id, uio_of_genirq_match[0].compatible, 128, 0);
 281 MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio");
 282 #endif
 283
 284 static struct platform_driver uio_pdrv_genirq = {
 285         .probe = uio_pdrv_genirq_probe,
 286         .driver = {
 287                 .name = DRIVER_NAME,
 288                 .pm = &uio_pdrv_genirq_dev_pm_ops,
 289                 .of_match_table = of_match_ptr(uio_of_genirq_match),
 290         },
 291 };
 292
 293 module_platform_driver(uio_pdrv_genirq);
 294
 295 MODULE_AUTHOR("Magnus Damm");
 296 MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
 297 MODULE_LICENSE("GPL v2");
 298 MODULE_ALIAS("platform:" DRIVER_NAME);