3 files changed, 202 insertions, 0 deletions

diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig
index 2e9079df26b3..4190be64917f 100644
--- a/drivers/uio/Kconfig
+++ b/drivers/uio/Kconfig
@@ -33,6 +33,19 @@ config UIO_PDRV
 
           If you don't know what to do here, say N.
 
+config UIO_PDRV_GENIRQ
+        tristate "Userspace I/O platform driver with generic IRQ handling"
+        help
+          Platform driver for Userspace I/O devices, including generic
+          interrupt handling code. Shared interrupts are not supported.
+
+          This kernel driver requires that the matching userspace driver
+          handles interrupts in a special way. Userspace is responsible
+          for acknowledging the hardware device if needed, and re-enabling
+          interrupts in the interrupt controller using the write() syscall.
+
+          If you don't know what to do here, say N.
+
 config UIO_SMX
         tristate "SMX cryptengine UIO interface"
         default n
diff --git a/drivers/uio/Makefile b/drivers/uio/Makefile
index e00ce0def1a0..8667bbdef904 100644
--- a/drivers/uio/Makefile
+++ b/drivers/uio/Makefile
@@ -1,4 +1,5 @@
 obj-$(CONFIG_UIO)       += uio.o
 obj-$(CONFIG_UIO_CIF)   += uio_cif.o
 obj-$(CONFIG_UIO_PDRV)  += uio_pdrv.o
+obj-$(CONFIG_UIO_PDRV_GENIRQ)   += uio_pdrv_genirq.o
 obj-$(CONFIG_UIO_SMX)   += uio_smx.o
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);