Re: [PATCH v2 1/1] input: add driver for Bosch Sensortec's BMA150 accelerometer

+Description:	This is used to select the full scale acceleration range. The
+		values represent the range given as +/- G.
+		Possible values are: 2, 4, 8.
+
+		Reading: returns the current acceleration range.
+
+		Writing: sets a new acceleration range.

As there is no way to know the valid values I suspect it ought to pick
nearest inclusive for others <=8 ?

Similarly for the others

+			normal - Sets the sensor in full running mode.
+			sleep  - Sets the sensor in deep sleep.
+			wakeup - Sets the sensor to low-power mode using
+				 sequential sleep period.
+
+		Reading: returns the current operational mode.
+
+		Writing: sets a new operational mode.

We have runtime_pm for this (and in fact to switch from the bma023 driver
I posted to yours we'd need runtime pm)

+
+
+What:		/sys/bus/i2c/devices/<busnum>-<devaddr>/value
+Date:		May 2011
+Contact:	Eric Andersson [off-list ref]
+Description:	This is used to get the current acceleration values for each
+		axis. The values are represented as (x,y,z), where each axis can
+		hold a value between -512 and 511.
+
+		Reading: returns the current acceleration values.

This was nacked in the bma023 driver by the IIO folks - and Dmitry
pointed out you can do this without a sysfs hack. The trick is to do an
initial poll in input_open at which point the ioctl query for the
position will have data that is current and open/ioctl/close works and
providing we go nail that into other drivers that need that kind of use
the API is generic and input event based.

+
+
+What:		/sys/bus/i2c/devices/<busnum>-<devaddr>/delay
+Date:		May 2011
+Contact:	Eric Andersson [off-list ref]
+Description:	This is used to select the polling rate of the driver. The
+		value is represented in ms and can be between 0 and 200. Any

0-200 whats ?

+What:		/sys/bus/i2c/devices/<busnum>-<devaddr>/enable
+Date:		May 2011
+Contact:	Eric Andersson [off-list ref]
+Description:	This is used to enable and disable the chip. The chip will only
+		be disabled if there are no input device users.

How does this differ from the power one and why is it needed, why doesn't
it disable when not in use ? How does this interact with runtime pm

+static int bma150_set_bandwidth(struct i2c_client *client, unsigned char bw)
+{
+	s32 ret;
+	unsigned char data;
+	struct bma150_data *bma150 = i2c_get_clientdata(client);
+
+	mutex_lock(&bma150->mutex);
+	ret = i2c_smbus_read_byte_data(client, BMA150_BANDWIDTH_REG);
+	if (ret < 0)
+		goto error;
+
+	data = (ret & ~BMA150_BANDWIDTH_MSK) |
+		((bw << BMA150_BANDWIDTH_POS) & BMA150_BANDWIDTH_MSK);
+
+	ret = i2c_smbus_write_byte_data(client, BMA150_BANDWIDTH_REG, data);
+error:
+	mutex_unlock(&bma150->mutex);
+	return ret;
+}

A lot of remarkably similar functions

+	mutex_lock(&bma150->mutex);
+	bma150->x = x;
+	bma150->y = y;
+	bma150->z = z;
+	mutex_unlock(&bma150->mutex);

This locking would go away if you dropped the un-needed sysfs node

+static int bma150_open(struct input_dev *inputdev)
+{
+	struct bma150_data *dev = input_get_drvdata(inputdev);
+
+	if (!dev->sysfs_enable)
+		return bma150_start_polling(inputdev);
+
+	return 0;
+}

Most bma023 users will be IRQ based, so this driver would need chunks
extracting from the other bma023 driver submission for that to be handled.

+
+static void bma150_close(struct input_dev *inputdev)
+{
+	struct bma150_data *dev = input_get_drvdata(inputdev);
+
+	if (!dev->sysfs_enable)
+		bma150_stop_polling(inputdev);

What locks sysfs_enable ?

From the Intel side to use your driver instead of bma023 we'd need IRQ

support and runtime pm but otherwise it looks basically ok. I really
don't see how to reconcile proper power management with all your sysfs
enables and power bits though ?