179  * Available scales with gain 1x - 1024x, timings 55, 100, 200, 400 mS
180  * Time impacts to gain: 1x, 2x, 4x, 8x.
182  * => Max total gain is HWGAIN * gain by integration time (8 * 1024) = 8192
187  * total gain 8192 will be 1953125
192  * On BU27010 available scales with gain 1x - 4096x,
193  * timings 55, 100, 200, 400 mS. Time impacts to gain: 1x, 2x, 4x, 8x.
195  * => Max total gain is HWGAIN * gain by integration time (8 * 4096)
197  * Using NANO precision for scale we must use scale 64x corresponding gain 1x
202 /* See the data sheet for the "Gain Setting" table */
292  * All the RGBC channels share the same gain.
293  * IR gain can be fine-tuned from the gain set for the RGBC by 2 bit, but this
294  * would yield quite complex gain setting. Especially since not all bit
295  * compinations are supported. And in any case setting GAIN for RGBC will
296  * always also change the IR-gain.
298  * On top of this, the selector '0' which corresponds to hw-gain 1X on RGBC,
299  * corresponds to gain 2X on IR. Rest of the selctors correspond to same gains
300  * though. This, however, makes it not possible to use shared gain for all
330 	 * We don't allow setting scale for IR (because of shared gain bits).
374 	 * Prevent changing gain/time config when scale is read/written.
376 	 * Prevent changing gain/time when data is read.
457 	 * gain and integration time settings and we need to ensure those are
487 	 * We do always set also the LOW bits of IR-gain because othervice we  in bu27008_write_gain_sel()
488 	 * would risk resulting an invalid GAIN register value.  in bu27008_write_gain_sel()
491 	 * values were such that HW could support both gain settings.  in bu27008_write_gain_sel()
492 	 * Eg, when the shared bits were same for both gain values.  in bu27008_write_gain_sel()
497 	 * This would end up with nasty logic for computing gain values for  in bu27008_write_gain_sel()
527 	 * Gain 'selector' is composed of two registers. Selector is 6bit value,  in bu27010_write_gain_sel()
528 	 * 4 high bits being the RGBC gain fieild in MODE_CONTROL1 register and  in bu27010_write_gain_sel()
529 	 * two low bits being the channel specific gain in MODE_CONTROL2.  in bu27010_write_gain_sel()
532 	 * the MODE_CONTROL1 value (RGBC gain part).  in bu27010_write_gain_sel()
561 	 * If we always "lock" the gain selectors for all channels to prevent  in bu27008_get_gain_sel()
587 	 * We always "lock" the gain selectors for all channels to prevent  in bu27010_get_gain_sel()
591 	 * Read the channel0 gain.  in bu27010_get_gain_sel()
599 	/* Read the shared gain */  in bu27010_get_gain_sel()
605 	 * The gain selector is made as a combination of common RGBC gain and  in bu27010_get_gain_sel()
606 	 * the channel specific gain. The channel specific gain forms the low  in bu27010_get_gain_sel()
607 	 * bits of selector and RGBC gain is appended right after it.  in bu27010_get_gain_sel()
609 	 * Compose the selector from channel0 gain and shared RGBC gain.  in bu27010_get_gain_sel()
760 static int bu27008_get_gain(struct bu27008_data *data, struct iio_gts *gts, int *gain)  in bu27008_get_gain()  argument
770 		dev_err(data->dev, "unknown gain value 0x%x\n", sel);  in bu27008_get_gain()
774 	*gain = ret;  in bu27008_get_gain()
779 static int bu27008_set_gain(struct bu27008_data *data, int gain)  in bu27008_set_gain()  argument
783 	ret = iio_gts_find_sel_by_gain(&data->gts, gain);  in bu27008_set_gain()
829 	int gain, ret;  in _bu27008_get_scale()  local
836 	ret = bu27008_get_gain(data, gts, &gain);  in _bu27008_get_scale()
844 	return iio_gts_get_scale(gts, gain, ret, val, val2);  in _bu27008_get_scale()
920 			dev_dbg(data->dev, "optimal gain out of range\n");  in bu27008_try_set_int_time()
924 				 "Total gain increase. Risk of saturation");  in bu27008_try_set_int_time()
930 		dev_dbg(data->dev, "scale changed, new gain %u\n", new_gain);  in bu27008_try_set_int_time()