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 void uio_pdrv_genirq_cleanup(void *data)
 103 {
 104         struct device *dev = data;
 105
 106         pm_runtime_disable(dev);
 107 }
 108
 109 static int uio_pdrv_genirq_probe(struct platform_device *pdev)
 110 {
 111         struct uio_info *uioinfo = dev_get_platdata(&pdev->dev);
 112         struct device_node *node = pdev->dev.of_node;
 113         struct uio_pdrv_genirq_platdata *priv;
 114         struct uio_mem *uiomem;
 115         int ret = -EINVAL;
 116         int i;
 117
 118         if (node) {
 119                 const char *name;
 120
 121                 /* alloc uioinfo for one device */
 122                 uioinfo = devm_kzalloc(&pdev->dev, sizeof(*uioinfo),
 123                                        GFP_KERNEL);
 124                 if (!uioinfo) {
 125                         dev_err(&pdev->dev, "unable to kmalloc\n");
 126                         return -ENOMEM;
 127                 }
 128
 129                 if (!of_property_read_string(node, "linux,uio-name", &name))
 130                         uioinfo->name = devm_kstrdup(&pdev->dev, name, GFP_KERNEL);
 131                 else
 132                         uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
 133                                                        "%pOFn", node);
 134
 135                 uioinfo->version = "devicetree";
 136                 /* Multiple IRQs are not supported */
 137         }
 138
 139         if (!uioinfo || !uioinfo->name || !uioinfo->version) {
 140                 dev_err(&pdev->dev, "missing platform_data\n");
 141                 return ret;
 142         }
 143
 144         if (uioinfo->handler || uioinfo->irqcontrol ||
 145             uioinfo->irq_flags & IRQF_SHARED) {
 146                 dev_err(&pdev->dev, "interrupt configuration error\n");
 147                 return ret;
 148         }
 149
 150         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 151         if (!priv) {
 152                 dev_err(&pdev->dev, "unable to kmalloc\n");
 153                 return -ENOMEM;
 154         }
 155
 156         priv->uioinfo = uioinfo;
 157         spin_lock_init(&priv->lock);
 158         priv->flags = 0; /* interrupt is enabled to begin with */
 159         priv->pdev = pdev;
 160
 161         if (!uioinfo->irq) {
 162                 ret = platform_get_irq(pdev, 0);
 163                 uioinfo->irq = ret;
 164                 if (ret == -ENXIO && pdev->dev.of_node)
 165                         uioinfo->irq = UIO_IRQ_NONE;
 166                 else if (ret == -EPROBE_DEFER)
 167                         return ret;
 168                 else if (ret < 0) {
 169                         dev_err(&pdev->dev, "failed to get IRQ\n");
 170                         return ret;
 171                 }
 172         }
 173
 174         uiomem = &uioinfo->mem[0];
 175
 176         for (i = 0; i < pdev->num_resources; ++i) {
 177                 struct resource *r = &pdev->resource[i];
 178
 179                 if (r->flags != IORESOURCE_MEM)
 180                         continue;
 181
 182                 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
 183                         dev_warn(&pdev->dev, "device has more than "
 184                                         __stringify(MAX_UIO_MAPS)
 185                                         " I/O memory resources.\n");
 186                         break;
 187                 }
 188
 189                 uiomem->memtype = UIO_MEM_PHYS;
 190                 uiomem->addr = r->start;
 191                 uiomem->size = resource_size(r);
 192                 uiomem->name = r->name;
 193                 ++uiomem;
 194         }
 195
 196         while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
 197                 uiomem->size = 0;
 198                 ++uiomem;
 199         }
 200
 201         /* This driver requires no hardware specific kernel code to handle
 202          * interrupts. Instead, the interrupt handler simply disables the
 203          * interrupt in the interrupt controller. User space is responsible
 204          * for performing hardware specific acknowledge and re-enabling of
 205          * the interrupt in the interrupt controller.
 206          *
 207          * Interrupt sharing is not supported.
 208          */
 209
 210         uioinfo->handler = uio_pdrv_genirq_handler;
 211         uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
 212         uioinfo->open = uio_pdrv_genirq_open;
 213         uioinfo->release = uio_pdrv_genirq_release;
 214         uioinfo->priv = priv;
 215
 216         /* Enable Runtime PM for this device:
 217          * The device starts in suspended state to allow the hardware to be
 218          * turned off by default. The Runtime PM bus code should power on the
 219          * hardware and enable clocks at open().
 220          */
 221         pm_runtime_enable(&pdev->dev);
 222
 223         ret = devm_add_action_or_reset(&pdev->dev, uio_pdrv_genirq_cleanup,
 224                                        &pdev->dev);
 225         if (ret)
 226                 return ret;
 227
 228         ret = devm_uio_register_device(&pdev->dev, priv->uioinfo);
 229         if (ret)
 230                 dev_err(&pdev->dev, "unable to register uio device\n");
 231
 232         return ret;
 233 }
 234
 235 static int uio_pdrv_genirq_runtime_nop(struct device *dev)
 236 {
 237         /* Runtime PM callback shared between ->runtime_suspend()
 238          * and ->runtime_resume(). Simply returns success.
 239          *
 240          * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
 241          * are used at open() and release() time. This allows the
 242          * Runtime PM code to turn off power to the device while the
 243          * device is unused, ie before open() and after release().
 244          *
 245          * This Runtime PM callback does not need to save or restore
 246          * any registers since user space is responsbile for hardware
 247          * register reinitialization after open().
 248          */
 249         return 0;
 250 }
 251
 252 static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
 253         .runtime_suspend = uio_pdrv_genirq_runtime_nop,
 254         .runtime_resume = uio_pdrv_genirq_runtime_nop,
 255 };
 256
 257 #ifdef CONFIG_OF
 258 static struct of_device_id uio_of_genirq_match[] = {
 259         { /* This is filled with module_parm */ },
 260         { /* Sentinel */ },
 261 };
 262 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
 263 module_param_string(of_id, uio_of_genirq_match[0].compatible, 128, 0);
 264 MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio");
 265 #endif
 266
 267 static struct platform_driver uio_pdrv_genirq = {
 268         .probe = uio_pdrv_genirq_probe,
 269         .driver = {
 270                 .name = DRIVER_NAME,
 271                 .pm = &uio_pdrv_genirq_dev_pm_ops,
 272                 .of_match_table = of_match_ptr(uio_of_genirq_match),
 273         },
 274 };
 275
 276 module_platform_driver(uio_pdrv_genirq);
 277
 278 MODULE_AUTHOR("Magnus Damm");
 279 MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
 280 MODULE_LICENSE("GPL v2");
 281 MODULE_ALIAS("platform:" DRIVER_NAME);