1 files changed, 54 insertions, 0 deletions

diff --git a/drivers/uio/uio_pdrv_genirq.c b/drivers/uio/uio_pdrv_genirq.c
index 3f06818cf9fa..02347c57357d 100644
--- a/drivers/uio/uio_pdrv_genirq.c
+++ b/drivers/uio/uio_pdrv_genirq.c
@@ -20,6 +20,7 @@
 #include <linux/bitops.h>
 #include <linux/interrupt.h>
 #include <linux/stringify.h>
+#include <linux/pm_runtime.h>
 
 #define DRIVER_NAME "uio_pdrv_genirq"
 
@@ -27,8 +28,27 @@ struct uio_pdrv_genirq_platdata {
         struct uio_info *uioinfo;
         spinlock_t lock;
         unsigned long flags;
+        struct platform_device *pdev;
 };
 
+static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode)
+{
+        struct uio_pdrv_genirq_platdata *priv = info->priv;
+
+        /* Wait until the Runtime PM code has woken up the device */
+        pm_runtime_get_sync(&priv->pdev->dev);
+        return 0;
+}
+
+static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode)
+{
+        struct uio_pdrv_genirq_platdata *priv = info->priv;
+
+        /* Tell the Runtime PM code that the device has become idle */
+        pm_runtime_put_sync(&priv->pdev->dev);
+        return 0;
+}
+
 static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info)
 {
         struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
@@ -97,6 +117,7 @@ static int uio_pdrv_genirq_probe(struct platform_device *pdev)
         priv->uioinfo = uioinfo;
         spin_lock_init(&priv->lock);
         priv->flags = 0; /* interrupt is enabled to begin with */
+        priv->pdev = pdev;
 
         uiomem = &uioinfo->mem[0];
 
@@ -136,8 +157,17 @@ static int uio_pdrv_genirq_probe(struct platform_device *pdev)
         uioinfo->irq_flags |= IRQF_DISABLED;
         uioinfo->handler = uio_pdrv_genirq_handler;
         uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
+        uioinfo->open = uio_pdrv_genirq_open;
+        uioinfo->release = uio_pdrv_genirq_release;
         uioinfo->priv = priv;
 
+        /* Enable Runtime PM for this device:
+         * The device starts in suspended state to allow the hardware to be
+         * turned off by default. The Runtime PM bus code should power on the
+         * hardware and enable clocks at open().
+         */
+        pm_runtime_enable(&pdev->dev);
+
         ret = uio_register_device(&pdev->dev, priv->uioinfo);
         if (ret) {
                 dev_err(&pdev->dev, "unable to register uio device\n");
@@ -157,16 +187,40 @@ static int uio_pdrv_genirq_remove(struct platform_device *pdev)
         struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev);
 
         uio_unregister_device(priv->uioinfo);
+        pm_runtime_disable(&pdev->dev);
         kfree(priv);
         return 0;
 }
 
+static int uio_pdrv_genirq_runtime_nop(struct device *dev)
+{
+        /* Runtime PM callback shared between ->runtime_suspend()
+         * and ->runtime_resume(). Simply returns success.
+         *
+         * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
+         * are used at open() and release() time. This allows the
+         * Runtime PM code to turn off power to the device while the
+         * device is unused, ie before open() and after release().
+         *
+         * This Runtime PM callback does not need to save or restore
+         * any registers since user space is responsbile for hardware
+         * register reinitialization after open().
+         */
+        return 0;
+}
+
+static struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
+        .runtime_suspend = uio_pdrv_genirq_runtime_nop,
+        .runtime_resume = uio_pdrv_genirq_runtime_nop,
+};
+
 static struct platform_driver uio_pdrv_genirq = {
         .probe = uio_pdrv_genirq_probe,
         .remove = uio_pdrv_genirq_remove,
         .driver = {
                 .name = DRIVER_NAME,
                 .owner = THIS_MODULE,
+                .pm = &uio_pdrv_genirq_dev_pm_ops,
         },
 };