HID: wiimote: Allow direct eeprom access

The wiimote provides direct access to parts of its eeprom. This implements read
support for small chunks of the eeprom. This isn't very fast but prevents the
reader from blocking the wiimote stream for too long.

Write support is not yet supported as the wiimote breaks if we overwrite its
memory. Use hidraw to reverse-engineer the eeprom before implementing write
support here.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 76 insertions, 0 deletions

diff --git a/drivers/hid/hid-wiimote-debug.c b/drivers/hid/hid-wiimote-debug.c
index 6282e3c1a362..f81243c86790 100644
--- a/drivers/hid/hid-wiimote-debug.c
+++ b/drivers/hid/hid-wiimote-debug.c
@@ -10,12 +10,80 @@
  * any later version.
  */
 
+#include <linux/debugfs.h>
 #include <linux/module.h>
 #include <linux/spinlock.h>
+#include <linux/uaccess.h>
 #include "hid-wiimote.h"
 
 struct wiimote_debug {
 	struct wiimote_data *wdata;
+	struct dentry *eeprom;
+};
+
+static int wiidebug_eeprom_open(struct inode *i, struct file *f)
+{
+	f->private_data = i->i_private;
+	return 0;
+}
+
+static ssize_t wiidebug_eeprom_read(struct file *f, char __user *u, size_t s,
+								loff_t *off)
+{
+	struct wiimote_debug *dbg = f->private_data;
+	struct wiimote_data *wdata = dbg->wdata;
+	unsigned long flags;
+	ssize_t ret;
+	char buf[16];
+	__u16 size;
+
+	if (s == 0)
+		return -EINVAL;
+	if (*off > 0xffffff)
+		return 0;
+	if (s > 16)
+		s = 16;
+
+	ret = wiimote_cmd_acquire(wdata);
+	if (ret)
+		return ret;
+
+	spin_lock_irqsave(&wdata->state.lock, flags);
+	wdata->state.cmd_read_size = s;
+	wdata->state.cmd_read_buf = buf;
+	wiimote_cmd_set(wdata, WIIPROTO_REQ_RMEM, *off & 0xffff);
+	wiiproto_req_reeprom(wdata, *off, s);
+	spin_unlock_irqrestore(&wdata->state.lock, flags);
+
+	ret = wiimote_cmd_wait(wdata);
+	if (!ret)
+		size = wdata->state.cmd_read_size;
+
+	spin_lock_irqsave(&wdata->state.lock, flags);
+	wdata->state.cmd_read_buf = NULL;
+	spin_unlock_irqrestore(&wdata->state.lock, flags);
+
+	wiimote_cmd_release(wdata);
+
+	if (ret)
+		return ret;
+	else if (size == 0)
+		return -EIO;
+
+	if (copy_to_user(u, buf, size))
+		return -EFAULT;
+
+	*off += size;
+	ret = size;
+
+	return ret;
+}
+
+static const struct file_operations wiidebug_eeprom_fops = {
+	.owner = THIS_MODULE,
+	.open = wiidebug_eeprom_open,
+	.read = wiidebug_eeprom_read,
+	.llseek = generic_file_llseek,
 };
 
 int wiidebug_init(struct wiimote_data *wdata)
@@ -29,6 +97,13 @@ int wiidebug_init(struct wiimote_data *wdata)
 
 	dbg->wdata = wdata;
 
+	dbg->eeprom = debugfs_create_file("eeprom", S_IRUSR,
+		dbg->wdata->hdev->debug_dir, dbg, &wiidebug_eeprom_fops);
+	if (!dbg->eeprom) {
+		kfree(dbg);
+		return -ENOMEM;
+	}
+
 	spin_lock_irqsave(&wdata->state.lock, flags);
 	wdata->debug = dbg;
 	spin_unlock_irqrestore(&wdata->state.lock, flags);
@@ -48,5 +123,6 @@ void wiidebug_deinit(struct wiimote_data *wdata)
 	wdata->debug = NULL;
 	spin_unlock_irqrestore(&wdata->state.lock, flags);
 
+	debugfs_remove(dbg->eeprom);
 	kfree(dbg);
 }