UIO: add generic UIO platform driver

This patch adds a generic UIO platform driver. It eliminates the need for a
dedicated kernel module for simple platform devices. Users only need to
implement their irq handler in platform code and fill a struct uio_info
there. This helps avoiding code duplication as UIO platform drivers often
share a lot of common code.

Signed-off-by: Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com>
Signed-off-by: Hans J. Koch <hjk@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/uio/Kconfig

@@ -26,6 +26,13 @@ config UIO_CIF
 	  To compile this driver as a module, choose M here: the module
 	  will be called uio_cif.
 
+config UIO_PDRV
+	tristate "Userspace I/O platform driver"
+	help
+	  Generic platform driver for Userspace I/O devices.
+
+	  If you don't know what to do here, say N.
+
 config UIO_SMX
 	tristate "SMX cryptengine UIO interface"
 	default n

drivers/uio/Makefile

@@ -1,3 +1,4 @@
 obj-$(CONFIG_UIO)	+= uio.o
 obj-$(CONFIG_UIO_CIF)	+= uio_cif.o
+obj-$(CONFIG_UIO_PDRV)	+= uio_pdrv.o
 obj-$(CONFIG_UIO_SMX)	+= uio_smx.o

drivers/uio/uio_pdrv.c

@@ -0,0 +1,118 @@
+/*
+ * drivers/uio/uio_pdrv.c
+ *
+ * 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/stringify.h>
+
+#define DRIVER_NAME "uio"
+
+struct uio_platdata {
+	struct uio_info *uioinfo;
+};
+
+static int uio_pdrv_probe(struct platform_device *pdev)
+{
+	struct uio_info *uioinfo = pdev->dev.platform_data;
+	struct uio_platdata *pdata;
+	struct uio_mem *uiomem;
+	int ret = -ENODEV;
+	int i;
+
+	if (!uioinfo || !uioinfo->name || !uioinfo->version) {
+		dev_dbg(&pdev->dev, "%s: err_uioinfo\n", __func__);
+		goto err_uioinfo;
+	}
+
+	pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
+	if (!pdata) {
+		ret = -ENOMEM;
+		dev_dbg(&pdev->dev, "%s: err_alloc_pdata\n", __func__);
+		goto err_alloc_pdata;
+	}
+
+	pdata->uioinfo = uioinfo;
+
+	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;
+	}
+
+	pdata->uioinfo->priv = pdata;
+
+	ret = uio_register_device(&pdev->dev, pdata->uioinfo);
+
+	if (ret) {
+		kfree(pdata);
+err_alloc_pdata:
+err_uioinfo:
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, pdata);
+
+	return 0;
+}
+
+static int uio_pdrv_remove(struct platform_device *pdev)
+{
+	struct uio_platdata *pdata = platform_get_drvdata(pdev);
+
+	uio_unregister_device(pdata->uioinfo);
+
+	return 0;
+}
+
+static struct platform_driver uio_pdrv = {
+	.probe = uio_pdrv_probe,
+	.remove = uio_pdrv_remove,
+	.driver = {
+		.name = DRIVER_NAME,
+		.owner = THIS_MODULE,
+	},
+};
+
+static int __init uio_pdrv_init(void)
+{
+	return platform_driver_register(&uio_pdrv);
+}
+
+static void __exit uio_pdrv_exit(void)
+{
+	platform_driver_unregister(&uio_pdrv);
+}
+module_init(uio_pdrv_init);
+module_exit(uio_pdrv_exit);
+
+MODULE_AUTHOR("Uwe Kleine-Koenig");
+MODULE_DESCRIPTION("Userspace I/O platform driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRIVER_NAME);