ARM: tegra: Add support for tegra registers access.

Add support for accesssing tegra registers from user space.

Original-Change-Id: Iae880a7c06b02c866501e50a6eceddea21969d62
Reviewed-on: http://git-master/r/27677
Reviewed-by: Niket Sirsi <nsirsi@nvidia.com>
Tested-by: Niket Sirsi <nsirsi@nvidia.com>
Change-Id: I9263121eacc6d93cd92421855c8caa0e1fed52f7

1 files changed, 110 insertions, 0 deletions

diff --git a/arch/arm/mach-tegra/tegra_reg_access.c b/arch/arm/mach-tegra/tegra_reg_access.c
new file mode 100644
index 000000000000..dd110a8fc5b0
--- /dev/null
+++ b/arch/arm/mach-tegra/tegra_reg_access.c
@@ -0,0 +1,110 @@
+/*
+ * arch/arm/mach-tegra/tegra_reg_access.c
+ *
+ * Copyright (C) 2011 NVIDIA Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/miscdevice.h>
+#include <linux/fs.h>
+#include <asm/io.h>
+#include <mach/iomap.h>
+
+static struct miscdevice dev;
+
+static int tegra_reg_access_open(struct inode *inode, struct file *filp)
+{
+	int ret;
+
+	ret = nonseekable_open(inode, filp);
+	if (unlikely(ret))
+		return ret;
+	return 0;
+}
+
+static int tegra_reg_access_release(struct inode *inode, struct file *filp)
+{
+	return 0;
+}
+
+#define TEGRA_REG_WRITE 0
+#define TEGRA_REG_READ 1
+
+static long tegra_reg_access_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+	/*
+	 * For Reg Read,
+	 * arg[0] = phys address, arg[1] = returns value read.
+	 * For Reg Write,
+	 * arg[0] = phys address, arg[1] = value to write.
+	 */
+	unsigned long *uarg = (unsigned long *)arg;
+	void __iomem *reg_addr = IO_ADDRESS(uarg[0]);
+
+	if (reg_addr == NULL)
+		return -EINVAL;
+
+	switch (cmd) {
+	case TEGRA_REG_READ:
+		uarg[1] = readl(reg_addr);
+		break;
+	case TEGRA_REG_WRITE:
+		writel(uarg[1], reg_addr);
+		break;
+	default:
+		pr_err("\n tegra_reg_access unknown ioctl cmd=%d\n", cmd);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static const struct file_operations tegra_reg_access_fops = {
+	.owner		= THIS_MODULE,
+	.open		= tegra_reg_access_open,
+	.release	= tegra_reg_access_release,
+	.unlocked_ioctl	= tegra_reg_access_ioctl,
+};
+
+static int __devinit tegra_reg_access_init(void)
+{
+	int e;
+
+	dev.minor = MISC_DYNAMIC_MINOR;
+	dev.name = "tegra_reg_access";
+	dev.fops = &tegra_reg_access_fops;
+	dev.parent = NULL;
+
+	e = misc_register(&dev);
+	if (e) {
+		pr_err("\nunable to register tegra_reg_access dev\n");
+		return -ENODEV;
+	}
+	pr_warn("## WARNING: Tegra registers access, from user space, is enabled.\n"
+		"## This creates a hole in the system security.\n"
+		"## Ensure that this is intentional.\n");
+	return 0;
+}
+
+static void __exit tegra_reg_access_exit(void)
+{
+	misc_deregister(&dev);
+}
+
+module_init(tegra_reg_access_init);
+module_exit(tegra_reg_access_exit);