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/of_platform.h>
  27 #include <linux/of_address.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 device_node *node = pdev->dev.of_node;
 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 (!of_property_read_string(node, "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                                                        "%pOFn", 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                 struct irq_data *irq_data = irq_get_irq_data(uioinfo->irq);
 177
 178                 /*
 179                  * If a level interrupt, dont do lazy disable. Otherwise the
 180                  * irq will fire again since clearing of the actual cause, on
 181                  * device level, is done in userspace
 182                  * irqd_is_level_type() isn't used since isn't valid until
 183                  * irq is configured.
 184                  */
 185                 if (irq_data &&
 186                     irqd_get_trigger_type(irq_data) & IRQ_TYPE_LEVEL_MASK) {
 187                         dev_dbg(&pdev->dev, "disable lazy unmask\n");
 188                         irq_set_status_flags(uioinfo->irq, IRQ_DISABLE_UNLAZY);
 189                 }
 190         }
 191
 192         uiomem = &uioinfo->mem[0];
 193
 194         for (i = 0; i < pdev->num_resources; ++i) {
 195                 struct resource *r = &pdev->resource[i];
 196
 197                 if (r->flags != IORESOURCE_MEM)
 198                         continue;
 199
 200                 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
 201                         dev_warn(&pdev->dev, "device has more than "
 202                                         __stringify(MAX_UIO_MAPS)
 203                                         " I/O memory resources.\n");
 204                         break;
 205                 }
 206
 207                 uiomem->memtype = UIO_MEM_PHYS;
 208                 uiomem->addr = r->start & PAGE_MASK;
 209                 uiomem->offs = r->start & ~PAGE_MASK;
 210                 uiomem->size = (uiomem->offs + resource_size(r)
 211                                 + PAGE_SIZE - 1) & PAGE_MASK;
 212                 uiomem->name = r->name;
 213                 ++uiomem;
 214         }
 215
 216         while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
 217                 uiomem->size = 0;
 218                 ++uiomem;
 219         }
 220
 221         /* This driver requires no hardware specific kernel code to handle
 222          * interrupts. Instead, the interrupt handler simply disables the
 223          * interrupt in the interrupt controller. User space is responsible
 224          * for performing hardware specific acknowledge and re-enabling of
 225          * the interrupt in the interrupt controller.
 226          *
 227          * Interrupt sharing is not supported.
 228          */
 229
 230         uioinfo->handler = uio_pdrv_genirq_handler;
 231         uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
 232         uioinfo->open = uio_pdrv_genirq_open;
 233         uioinfo->release = uio_pdrv_genirq_release;
 234         uioinfo->priv = priv;
 235
 236         /* Enable Runtime PM for this device:
 237          * The device starts in suspended state to allow the hardware to be
 238          * turned off by default. The Runtime PM bus code should power on the
 239          * hardware and enable clocks at open().
 240          */
 241         pm_runtime_enable(&pdev->dev);
 242
 243         ret = devm_add_action_or_reset(&pdev->dev, uio_pdrv_genirq_cleanup,
 244                                        &pdev->dev);
 245         if (ret)
 246                 return ret;
 247
 248         ret = devm_uio_register_device(&pdev->dev, priv->uioinfo);
 249         if (ret)
 250                 dev_err(&pdev->dev, "unable to register uio device\n");
 251
 252         return ret;
 253 }
 254
 255 static int uio_pdrv_genirq_runtime_nop(struct device *dev)
 256 {
 257         /* Runtime PM callback shared between ->runtime_suspend()
 258          * and ->runtime_resume(). Simply returns success.
 259          *
 260          * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
 261          * are used at open() and release() time. This allows the
 262          * Runtime PM code to turn off power to the device while the
 263          * device is unused, ie before open() and after release().
 264          *
 265          * This Runtime PM callback does not need to save or restore
 266          * any registers since user space is responsbile for hardware
 267          * register reinitialization after open().
 268          */
 269         return 0;
 270 }
 271
 272 static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
 273         .runtime_suspend = uio_pdrv_genirq_runtime_nop,
 274         .runtime_resume = uio_pdrv_genirq_runtime_nop,
 275 };
 276
 277 #ifdef CONFIG_OF
 278 static struct of_device_id uio_of_genirq_match[] = {
 279         { /* This is filled with module_parm */ },
 280         { /* Sentinel */ },
 281 };
 282 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
 283 module_param_string(of_id, uio_of_genirq_match[0].compatible, 128, 0);
 284 MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio");
 285 #endif
 286
 287 static struct platform_driver uio_pdrv_genirq = {
 288         .probe = uio_pdrv_genirq_probe,
 289         .driver = {
 290                 .name = DRIVER_NAME,
 291                 .pm = &uio_pdrv_genirq_dev_pm_ops,
 292                 .of_match_table = of_match_ptr(uio_of_genirq_match),
 293         },
 294 };
 295
 296 module_platform_driver(uio_pdrv_genirq);
 297
 298 MODULE_AUTHOR("Magnus Damm");
 299 MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
 300 MODULE_LICENSE("GPL v2");
 301 MODULE_ALIAS("platform:" DRIVER_NAME);