183  * Available scales with gain 1x - 1024x, timings 55, 100, 200, 400 mS
184  * Time impacts to gain: 1x, 2x, 4x, 8x.
186  * => Max total gain is HWGAIN * gain by integration time (8 * 1024) = 8192
191  * total gain 8192 will be 1953125
196  * On BU27010 available scales with gain 1x - 4096x,
197  * timings 55, 100, 200, 400 mS. Time impacts to gain: 1x, 2x, 4x, 8x.
199  * => Max total gain is HWGAIN * gain by integration time (8 * 4096)
201  * Using NANO precision for scale we must use scale 64x corresponding gain 1x
206 /* See the data sheet for the "Gain Setting" table */
296  * All the RGBC channels share the same gain.
297  * IR gain can be fine-tuned from the gain set for the RGBC by 2 bit, but this
298  * would yield quite complex gain setting. Especially since not all bit
299  * compinations are supported. And in any case setting GAIN for RGBC will
300  * always also change the IR-gain.
302  * On top of this, the selector '0' which corresponds to hw-gain 1X on RGBC,
303  * corresponds to gain 2X on IR. Rest of the selctors correspond to same gains
304  * though. This, however, makes it not possible to use shared gain for all
334 	 * We don't allow setting scale for IR (because of shared gain bits).
391 	 * Prevent changing gain/time config when scale is read/written.
393 	 * Prevent changing gain/time when data is read.
474 	 * gain and integration time settings and we need to ensure those are
504 	 * We do always set also the LOW bits of IR-gain because othervice we  in bu27008_write_gain_sel()
505 	 * would risk resulting an invalid GAIN register value.  in bu27008_write_gain_sel()
508 	 * values were such that HW could support both gain settings.  in bu27008_write_gain_sel()
509 	 * Eg, when the shared bits were same for both gain values.  in bu27008_write_gain_sel()
514 	 * This would end up with nasty logic for computing gain values for  in bu27008_write_gain_sel()
544 	 * Gain 'selector' is composed of two registers. Selector is 6bit value,  in bu27010_write_gain_sel()
545 	 * 4 high bits being the RGBC gain fieild in MODE_CONTROL1 register and  in bu27010_write_gain_sel()
546 	 * two low bits being the channel specific gain in MODE_CONTROL2.  in bu27010_write_gain_sel()
549 	 * the MODE_CONTROL1 value (RGBC gain part).  in bu27010_write_gain_sel()
578 	 * If we always "lock" the gain selectors for all channels to prevent  in bu27008_get_gain_sel()
604 	 * We always "lock" the gain selectors for all channels to prevent  in bu27010_get_gain_sel()
608 	 * Read the channel0 gain.  in bu27010_get_gain_sel()
616 	/* Read the shared gain */  in bu27010_get_gain_sel()
622 	 * The gain selector is made as a combination of common RGBC gain and  in bu27010_get_gain_sel()
623 	 * the channel specific gain. The channel specific gain forms the low  in bu27010_get_gain_sel()
624 	 * bits of selector and RGBC gain is appended right after it.  in bu27010_get_gain_sel()
626 	 * Compose the selector from channel0 gain and shared RGBC gain.  in bu27010_get_gain_sel()
777 static int bu27008_get_gain(struct bu27008_data *data, struct iio_gts *gts, int *gain)  in bu27008_get_gain()  argument
787 		dev_err(data->dev, "unknown gain value 0x%x\n", sel);  in bu27008_get_gain()
791 	*gain = ret;  in bu27008_get_gain()
796 static int bu27008_set_gain(struct bu27008_data *data, int gain)  in bu27008_set_gain()  argument
800 	ret = iio_gts_find_sel_by_gain(&data->gts, gain);  in bu27008_set_gain()
846 	int gain, ret;  in _bu27008_get_scale()  local
853 	ret = bu27008_get_gain(data, gts, &gain);  in _bu27008_get_scale()
861 	return iio_gts_get_scale(gts, gain, ret, val, val2);  in _bu27008_get_scale()
937 			dev_dbg(data->dev, "optimal gain out of range\n");  in bu27008_try_set_int_time()
941 				 "Total gain increase. Risk of saturation");  in bu27008_try_set_int_time()
947 		dev_dbg(data->dev, "scale changed, new gain %u\n", new_gain);  in bu27008_try_set_int_time()
1071  * Red = RedData*1024 / Gain * 20 / meas_mode
1072  * Green = GreenData* 1024 / Gain * 20 / meas_mode
1073  * Blue = BlueData* 1024 / Gain * 20 / meas_mode
1074  * IR = IrData* 1024 / Gain * 20 / meas_mode
1091 #define NORM_CHAN_DATA_FOR_LX_CALC(chan, gain, time) (le16_to_cpu(chan) * \  argument
1092 				   1024 * 20 / (gain) / (time))
1094 		unsigned int gain, unsigned int gain_ir, unsigned int time)  in bu27008_calc_nlux()  argument
1101 	red = NORM_CHAN_DATA_FOR_LX_CALC(lux_data[BU27008_LUX_DATA_RED], gain, time);  in bu27008_calc_nlux()
1102 	green = NORM_CHAN_DATA_FOR_LX_CALC(lux_data[BU27008_LUX_DATA_GREEN], gain, time);  in bu27008_calc_nlux()
1103 	blue = NORM_CHAN_DATA_FOR_LX_CALC(lux_data[BU27008_LUX_DATA_BLUE], gain, time);  in bu27008_calc_nlux()
1120 		unsigned int *gain, unsigned int *gain_ir, unsigned int *time)  in bu27008_get_time_n_gains()  argument
1124 	ret = bu27008_get_gain(data, &data->gts, gain);  in bu27008_get_time_n_gains()
1151 	unsigned int gain, gain_ir, time;  in bu27008_buffer_fill_lux()  local
1154 	ret = bu27008_get_time_n_gains(data, &gain, &gain_ir, &time);  in bu27008_buffer_fill_lux()
1158 	raw->lux = bu27008_calc_nlux(data, raw->chan, gain, gain_ir, time);  in bu27008_buffer_fill_lux()
1168 	unsigned int gain, gain_ir, time;  in bu27008_read_lux()  local
1172 	ret = bu27008_get_time_n_gains(data, &gain, &gain_ir, &time);  in bu27008_read_lux()
1180 	nlux = bu27008_calc_nlux(data, lux_data, gain, gain_ir, time);  in bu27008_read_lux()