[PATCH 21/21] HID: wiimote: add "bboard_calib" attribute

[David Herrmann <dh.herrmann@gmail.com>]

Balance-Boards provide 3 16bit calibration values for each of the 4
sensors. We provide these now as 192bit value via a new "bboard_calib"
sysfs attribute.
We also re-read the calibration data from the device whenever user-space
attempts to read this file. On normal Nintendo boards, this always
produces the same results, however, on some 3rd party devices these values
change until the device is fully initialized. As I have currently no idea
how long to wait until it's ready (sometimes takes up to 10s?) we provide
a simple workaround for users by reading this file.

If we, at some point, figure out how it works, we can implement it in the
kernel and provide offline data via "bboard_calib". This won't break
user-space then.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
---
 drivers/hid/hid-wiimote-modules.c | 68 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 67 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/hid-wiimote-modules.c b/drivers/hid/hid-wiimote-modules.c
index c3e823d..6e43917 100644
--- a/drivers/hid/hid-wiimote-modules.c
+++ b/drivers/hid/hid-wiimote-modules.c
@@ -1380,6 +1380,60 @@ static void wiimod_bboard_close(struct input_dev *dev)
 	spin_unlock_irqrestore(&wdata->state.lock, flags);
 }
 
+static ssize_t wiimod_bboard_calib_show(struct device *dev,
+					struct device_attribute *attr,
+					char *out)
+{
+	struct wiimote_data *wdata = dev_to_wii(dev);
+	int i, j, ret;
+	__u16 val;
+	__u8 buf[24], offs;
+
+	ret = wiimote_cmd_acquire(wdata);
+	if (ret)
+		return ret;
+
+	ret = wiimote_cmd_read(wdata, 0xa40024, buf, 12);
+	if (ret != 12) {
+		wiimote_cmd_release(wdata);
+		return ret < 0 ? ret : -EIO;
+	}
+	ret = wiimote_cmd_read(wdata, 0xa40024 + 12, buf + 12, 12);
+	if (ret != 12) {
+		wiimote_cmd_release(wdata);
+		return ret < 0 ? ret : -EIO;
+	}
+
+	wiimote_cmd_release(wdata);
+
+	spin_lock_irq(&wdata->state.lock);
+	offs = 0;
+	for (i = 0; i < 3; ++i) {
+		for (j = 0; j < 4; ++j) {
+			wdata->state.calib_bboard[j][i] = buf[offs];
+			wdata->state.calib_bboard[j][i] <<= 8;
+			wdata->state.calib_bboard[j][i] |= buf[offs + 1];
+			offs += 2;
+		}
+	}
+	spin_unlock_irq(&wdata->state.lock);
+
+	ret = 0;
+	for (i = 0; i < 3; ++i) {
+		for (j = 0; j < 4; ++j) {
+			val = wdata->state.calib_bboard[j][i];
+			if (i == 2 && j == 3)
+				ret += sprintf(&out[ret], "%04x\n", val);
+			else
+				ret += sprintf(&out[ret], "%04x:", val);
+		}
+	}
+
+	return ret;
+}
+
+static DEVICE_ATTR(bboard_calib, S_IRUGO, wiimod_bboard_calib_show, NULL);
+
 static int wiimod_bboard_probe(const struct wiimod_ops *ops,
 			       struct wiimote_data *wdata)
 {
@@ -1415,6 +1469,13 @@ static int wiimod_bboard_probe(const struct wiimod_ops *ops,
 	if (!wdata->extension.input)
 		return -ENOMEM;
 
+	ret = device_create_file(&wdata->hdev->dev,
+				 &dev_attr_bboard_calib);
+	if (ret) {
+		hid_err(wdata->hdev, "cannot create sysfs attribute\n");
+		goto err_free;
+	}
+
 	input_set_drvdata(wdata->extension.input, wdata);
 	wdata->extension.input->open = wiimod_bboard_open;
 	wdata->extension.input->close = wiimod_bboard_close;
@@ -1444,10 +1505,13 @@ static int wiimod_bboard_probe(const struct wiimod_ops *ops,
 
 	ret = input_register_device(wdata->extension.input);
 	if (ret)
-		goto err_free;
+		goto err_file;
 
 	return 0;
 
+err_file:
+	device_remove_file(&wdata->hdev->dev,
+			   &dev_attr_bboard_calib);
 err_free:
 	input_free_device(wdata->extension.input);
 	wdata->extension.input = NULL;
@@ -1462,6 +1526,8 @@ static void wiimod_bboard_remove(const struct wiimod_ops *ops,
 
 	input_unregister_device(wdata->extension.input);
 	wdata->extension.input = NULL;
+	device_remove_file(&wdata->hdev->dev,
+			   &dev_attr_bboard_calib);
 }
 
 static const struct wiimod_ops wiimod_bboard = {
-- 
1.8.2.1