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path: root/drivers/uio/uio_pdrv_genirq.c
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Diffstat (limited to 'drivers/uio/uio_pdrv_genirq.c')
-rw-r--r--drivers/uio/uio_pdrv_genirq.c188
1 files changed, 188 insertions, 0 deletions
diff --git a/drivers/uio/uio_pdrv_genirq.c b/drivers/uio/uio_pdrv_genirq.c
new file mode 100644
index 000000000000..1f82c83a92ae
--- /dev/null
+++ b/drivers/uio/uio_pdrv_genirq.c
@@ -0,0 +1,188 @@
+/*
+ * drivers/uio/uio_pdrv_genirq.c
+ *
+ * Userspace I/O platform driver with generic IRQ handling code.
+ *
+ * Copyright (C) 2008 Magnus Damm
+ *
+ * Based on uio_pdrv.c by Uwe Kleine-Koenig,
+ * Copyright (C) 2008 by Digi International Inc.
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/uio_driver.h>
+#include <linux/spinlock.h>
+#include <linux/bitops.h>
+#include <linux/interrupt.h>
+#include <linux/stringify.h>
+
+#define DRIVER_NAME "uio_pdrv_genirq"
+
+struct uio_pdrv_genirq_platdata {
+ struct uio_info *uioinfo;
+ spinlock_t lock;
+ unsigned long flags;
+};
+
+static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info)
+{
+ struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
+
+ /* Just disable the interrupt in the interrupt controller, and
+ * remember the state so we can allow user space to enable it later.
+ */
+
+ if (!test_and_set_bit(0, &priv->flags))
+ disable_irq_nosync(irq);
+
+ return IRQ_HANDLED;
+}
+
+static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
+{
+ struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
+ unsigned long flags;
+
+ /* Allow user space to enable and disable the interrupt
+ * in the interrupt controller, but keep track of the
+ * state to prevent per-irq depth damage.
+ *
+ * Serialize this operation to support multiple tasks.
+ */
+
+ spin_lock_irqsave(&priv->lock, flags);
+ if (irq_on) {
+ if (test_and_clear_bit(0, &priv->flags))
+ enable_irq(dev_info->irq);
+ } else {
+ if (!test_and_set_bit(0, &priv->flags))
+ disable_irq(dev_info->irq);
+ }
+ spin_unlock_irqrestore(&priv->lock, flags);
+
+ return 0;
+}
+
+static int uio_pdrv_genirq_probe(struct platform_device *pdev)
+{
+ struct uio_info *uioinfo = pdev->dev.platform_data;
+ struct uio_pdrv_genirq_platdata *priv;
+ struct uio_mem *uiomem;
+ int ret = -EINVAL;
+ int i;
+
+ if (!uioinfo || !uioinfo->name || !uioinfo->version) {
+ dev_err(&pdev->dev, "missing platform_data\n");
+ goto bad0;
+ }
+
+ if (uioinfo->handler || uioinfo->irqcontrol || uioinfo->irq_flags) {
+ dev_err(&pdev->dev, "interrupt configuration error\n");
+ goto bad0;
+ }
+
+ priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+ if (!priv) {
+ ret = -ENOMEM;
+ dev_err(&pdev->dev, "unable to kmalloc\n");
+ goto bad0;
+ }
+
+ priv->uioinfo = uioinfo;
+ spin_lock_init(&priv->lock);
+ priv->flags = 0; /* interrupt is enabled to begin with */
+
+ uiomem = &uioinfo->mem[0];
+
+ for (i = 0; i < pdev->num_resources; ++i) {
+ struct resource *r = &pdev->resource[i];
+
+ if (r->flags != IORESOURCE_MEM)
+ continue;
+
+ if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
+ dev_warn(&pdev->dev, "device has more than "
+ __stringify(MAX_UIO_MAPS)
+ " I/O memory resources.\n");
+ break;
+ }
+
+ uiomem->memtype = UIO_MEM_PHYS;
+ uiomem->addr = r->start;
+ uiomem->size = r->end - r->start + 1;
+ ++uiomem;
+ }
+
+ while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
+ uiomem->size = 0;
+ ++uiomem;
+ }
+
+ /* This driver requires no hardware specific kernel code to handle
+ * interrupts. Instead, the interrupt handler simply disables the
+ * interrupt in the interrupt controller. User space is responsible
+ * for performing hardware specific acknowledge and re-enabling of
+ * the interrupt in the interrupt controller.
+ *
+ * Interrupt sharing is not supported.
+ */
+
+ uioinfo->irq_flags = IRQF_DISABLED;
+ uioinfo->handler = uio_pdrv_genirq_handler;
+ uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
+ uioinfo->priv = priv;
+
+ ret = uio_register_device(&pdev->dev, priv->uioinfo);
+ if (ret) {
+ dev_err(&pdev->dev, "unable to register uio device\n");
+ goto bad1;
+ }
+
+ platform_set_drvdata(pdev, priv);
+ return 0;
+ bad1:
+ kfree(priv);
+ bad0:
+ return ret;
+}
+
+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);
+ kfree(priv);
+ return 0;
+}
+
+static struct platform_driver uio_pdrv_genirq = {
+ .probe = uio_pdrv_genirq_probe,
+ .remove = uio_pdrv_genirq_remove,
+ .driver = {
+ .name = DRIVER_NAME,
+ .owner = THIS_MODULE,
+ },
+};
+
+static int __init uio_pdrv_genirq_init(void)
+{
+ return platform_driver_register(&uio_pdrv_genirq);
+}
+
+static void __exit uio_pdrv_genirq_exit(void)
+{
+ platform_driver_unregister(&uio_pdrv_genirq);
+}
+
+module_init(uio_pdrv_genirq_init);
+module_exit(uio_pdrv_genirq_exit);
+
+MODULE_AUTHOR("Magnus Damm");
+MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" DRIVER_NAME);