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