ACPI: introduce drivers/acpi/debugfs.c

Introduce drivers/acpi/debugfs.c.

Code for ACPI debugfs I/F,
i.e. /sys/kernel/debug/acpi/custom_method,
is moved to this file.

And make ACPI debugfs always built in,
even if CONFIG_ACPI_DEBUG is cleared.

BTW:this adds about 400bytes code to ACPI, when
CONFIG_ACPI_DEBUG is cleared.

[uaccess.h build fix from Andrew Morton <akpm@linux-foundation.org>]

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 85 insertions, 0 deletions

diff --git a/drivers/acpi/debugfs.c b/drivers/acpi/debugfs.c
new file mode 100644
index 00000000000..abfcf9f6e76
--- /dev/null
+++ b/drivers/acpi/debugfs.c
@@ -0,0 +1,85 @@
+/*
+ * debugfs.c - ACPI debugfs interface to userspace.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/uaccess.h>
+#include <linux/debugfs.h>
+#include <acpi/acpi_drivers.h>
+
+#define _COMPONENT		ACPI_SYSTEM_COMPONENT
+ACPI_MODULE_NAME("debugfs");
+
+/* /sys/kernel/debug/acpi/custom_method */
+
+static ssize_t cm_write(struct file *file, const char __user * user_buf,
+			size_t count, loff_t *ppos)
+{
+	static char *buf;
+	static int uncopied_bytes;
+	struct acpi_table_header table;
+	acpi_status status;
+
+	if (!(*ppos)) {
+		/* parse the table header to get the table length */
+		if (count <= sizeof(struct acpi_table_header))
+			return -EINVAL;
+		if (copy_from_user(&table, user_buf,
+				   sizeof(struct acpi_table_header)))
+			return -EFAULT;
+		uncopied_bytes = table.length;
+		buf = kzalloc(uncopied_bytes, GFP_KERNEL);
+		if (!buf)
+			return -ENOMEM;
+	}
+
+	if (uncopied_bytes < count) {
+		kfree(buf);
+		return -EINVAL;
+	}
+
+	if (copy_from_user(buf + (*ppos), user_buf, count)) {
+		kfree(buf);
+		return -EFAULT;
+	}
+
+	uncopied_bytes -= count;
+	*ppos += count;
+
+	if (!uncopied_bytes) {
+		status = acpi_install_method(buf);
+		kfree(buf);
+		if (ACPI_FAILURE(status))
+			return -EINVAL;
+		add_taint(TAINT_OVERRIDDEN_ACPI_TABLE);
+	}
+
+	return count;
+}
+
+static const struct file_operations cm_fops = {
+	.write = cm_write,
+};
+
+int __init acpi_debugfs_init(void)
+{
+	struct dentry *acpi_dir, *cm_dentry;
+
+	acpi_dir = debugfs_create_dir("acpi", NULL);
+	if (!acpi_dir)
+		goto err;
+
+	cm_dentry = debugfs_create_file("custom_method", S_IWUGO,
+					acpi_dir, NULL, &cm_fops);
+	if (!cm_dentry)
+		goto err;
+
+	return 0;
+
+err:
+	if (acpi_dir)
+		debugfs_remove(acpi_dir);
+	return -EINVAL;
+}