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 000000000000..abfcf9f6e766
--- /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;
+}