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1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 | // SPDX-License-Identifier: GPL-2.0-only /* * BU27034 ROHM Ambient Light Sensor * * Copyright (c) 2023, ROHM Semiconductor. * https://fscdn.rohm.com/en/products/databook/datasheet/ic/sensor/light/bu27034nuc-e.pdf */ #include <linux/bitfield.h> #include <linux/bits.h> #include <linux/device.h> #include <linux/i2c.h> #include <linux/module.h> #include <linux/property.h> #include <linux/regmap.h> #include <linux/regulator/consumer.h> #include <linux/units.h> #include <linux/iio/buffer.h> #include <linux/iio/iio.h> #include <linux/iio/iio-gts-helper.h> #include <linux/iio/kfifo_buf.h> #define BU27034_REG_SYSTEM_CONTROL 0x40 #define BU27034_MASK_SW_RESET BIT(7) #define BU27034_MASK_PART_ID GENMASK(5, 0) #define BU27034_ID 0x19 #define BU27034_REG_MODE_CONTROL1 0x41 #define BU27034_MASK_MEAS_MODE GENMASK(2, 0) #define BU27034_REG_MODE_CONTROL2 0x42 #define BU27034_MASK_D01_GAIN GENMASK(7, 3) #define BU27034_MASK_D2_GAIN_HI GENMASK(7, 6) #define BU27034_MASK_D2_GAIN_LO GENMASK(2, 0) #define BU27034_REG_MODE_CONTROL3 0x43 #define BU27034_REG_MODE_CONTROL4 0x44 #define BU27034_MASK_MEAS_EN BIT(0) #define BU27034_MASK_VALID BIT(7) #define BU27034_REG_DATA0_LO 0x50 #define BU27034_REG_DATA1_LO 0x52 #define BU27034_REG_DATA2_LO 0x54 #define BU27034_REG_DATA2_HI 0x55 #define BU27034_REG_MANUFACTURER_ID 0x92 #define BU27034_REG_MAX BU27034_REG_MANUFACTURER_ID /* * The BU27034 does not have interrupt to trigger the data read when a * measurement has finished. Hence we poll the VALID bit in a thread. We will * try to wake the thread BU27034_MEAS_WAIT_PREMATURE_MS milliseconds before * the expected sampling time to prevent the drifting. * * If we constantly wake up a bit too late we would eventually skip a sample. * And because the sleep can't wake up _exactly_ at given time this would be * inevitable even if the sensor clock would be perfectly phase-locked to CPU * clock - which we can't say is the case. * * This is still fragile. No matter how big advance do we have, we will still * risk of losing a sample because things can in a rainy-day scenario be * delayed a lot. Yet, more we reserve the time for polling, more we also lose * the performance by spending cycles polling the register. So, selecting this * value is a balancing dance between severity of wasting CPU time and severity * of losing samples. * * In most cases losing the samples is not _that_ crucial because light levels * tend to change slowly. * * Other option that was pointed to me would be always sleeping 1/2 of the * measurement time, checking the VALID bit and just sleeping again if the bit * was not set. That should be pretty tolerant against missing samples due to * the scheduling delays while also not wasting much of cycles for polling. * Downside is that the time-stamps would be very inaccurate as the wake-up * would not really be tied to the sensor toggling the valid bit. This would also * result 'jumps' in the time-stamps when the delay drifted so that wake-up was * performed during the consecutive wake-ups (Or, when sensor and CPU clocks * were very different and scheduling the wake-ups was very close to given * timeout - and when the time-outs were very close to the actual sensor * sampling, Eg. once in a blue moon, two consecutive time-outs would occur * without having a sample ready). */ #define BU27034_MEAS_WAIT_PREMATURE_MS 5 #define BU27034_DATA_WAIT_TIME_US 1000 #define BU27034_TOTAL_DATA_WAIT_TIME_US (BU27034_MEAS_WAIT_PREMATURE_MS * 1000) #define BU27034_RETRY_LIMIT 18 enum { BU27034_CHAN_ALS, BU27034_CHAN_DATA0, BU27034_CHAN_DATA1, BU27034_CHAN_DATA2, BU27034_NUM_CHANS }; static const unsigned long bu27034_scan_masks[] = { GENMASK(BU27034_CHAN_DATA2, BU27034_CHAN_ALS), 0 }; /* * Available scales with gain 1x - 4096x, timings 55, 100, 200, 400 mS * Time impacts to gain: 1x, 2x, 4x, 8x. * * => Max total gain is HWGAIN * gain by integration time (8 * 4096) = 32768 * * Using NANO precision for scale we must use scale 64x corresponding gain 1x * to avoid precision loss. (32x would result scale 976 562.5(nanos). */ #define BU27034_SCALE_1X 64 /* See the data sheet for the "Gain Setting" table */ #define BU27034_GSEL_1X 0x00 /* 00000 */ #define BU27034_GSEL_4X 0x08 /* 01000 */ #define BU27034_GSEL_16X 0x0a /* 01010 */ #define BU27034_GSEL_32X 0x0b /* 01011 */ #define BU27034_GSEL_64X 0x0c /* 01100 */ #define BU27034_GSEL_256X 0x18 /* 11000 */ #define BU27034_GSEL_512X 0x19 /* 11001 */ #define BU27034_GSEL_1024X 0x1a /* 11010 */ #define BU27034_GSEL_2048X 0x1b /* 11011 */ #define BU27034_GSEL_4096X 0x1c /* 11100 */ /* Available gain settings */ static const struct iio_gain_sel_pair bu27034_gains[] = { GAIN_SCALE_GAIN(1, BU27034_GSEL_1X), GAIN_SCALE_GAIN(4, BU27034_GSEL_4X), GAIN_SCALE_GAIN(16, BU27034_GSEL_16X), GAIN_SCALE_GAIN(32, BU27034_GSEL_32X), GAIN_SCALE_GAIN(64, BU27034_GSEL_64X), GAIN_SCALE_GAIN(256, BU27034_GSEL_256X), GAIN_SCALE_GAIN(512, BU27034_GSEL_512X), GAIN_SCALE_GAIN(1024, BU27034_GSEL_1024X), GAIN_SCALE_GAIN(2048, BU27034_GSEL_2048X), GAIN_SCALE_GAIN(4096, BU27034_GSEL_4096X), }; /* * The IC has 5 modes for sampling time. 5 mS mode is exceptional as it limits * the data collection to data0-channel only and cuts the supported range to * 10 bit. It is not supported by the driver. * * "normal" modes are 55, 100, 200 and 400 mS modes - which do have direct * multiplying impact to the register values (similar to gain). * * This means that if meas-mode is changed for example from 400 => 200, * the scale is doubled. Eg, time impact to total gain is x1, x2, x4, x8. */ #define BU27034_MEAS_MODE_100MS 0 #define BU27034_MEAS_MODE_55MS 1 #define BU27034_MEAS_MODE_200MS 2 #define BU27034_MEAS_MODE_400MS 4 static const struct iio_itime_sel_mul bu27034_itimes[] = { GAIN_SCALE_ITIME_US(400000, BU27034_MEAS_MODE_400MS, 8), GAIN_SCALE_ITIME_US(200000, BU27034_MEAS_MODE_200MS, 4), GAIN_SCALE_ITIME_US(100000, BU27034_MEAS_MODE_100MS, 2), GAIN_SCALE_ITIME_US(55000, BU27034_MEAS_MODE_55MS, 1), }; #define BU27034_CHAN_DATA(_name, _ch2) \ { \ .type = IIO_INTENSITY, \ .channel = BU27034_CHAN_##_name, \ .channel2 = (_ch2), \ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \ BIT(IIO_CHAN_INFO_SCALE), \ .info_mask_separate_available = BIT(IIO_CHAN_INFO_SCALE), \ .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME), \ .info_mask_shared_by_all_available = \ BIT(IIO_CHAN_INFO_INT_TIME), \ .address = BU27034_REG_##_name##_LO, \ .scan_index = BU27034_CHAN_##_name, \ .scan_type = { \ .sign = 'u', \ .realbits = 16, \ .storagebits = 16, \ .endianness = IIO_LE, \ }, \ .indexed = 1, \ } static const struct iio_chan_spec bu27034_channels[] = { { .type = IIO_LIGHT, .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), .channel = BU27034_CHAN_ALS, .scan_index = BU27034_CHAN_ALS, .scan_type = { .sign = 'u', .realbits = 32, .storagebits = 32, .endianness = IIO_CPU, }, }, /* * The BU27034 DATA0 and DATA1 channels are both on the visible light * area (mostly). The data0 sensitivity peaks at 500nm, DATA1 at 600nm. * These wave lengths are pretty much on the border of colours making * these a poor candidates for R/G/B standardization. Hence they're both * marked as clear channels */ BU27034_CHAN_DATA(DATA0, IIO_MOD_LIGHT_CLEAR), BU27034_CHAN_DATA(DATA1, IIO_MOD_LIGHT_CLEAR), BU27034_CHAN_DATA(DATA2, IIO_MOD_LIGHT_IR), IIO_CHAN_SOFT_TIMESTAMP(4), }; struct bu27034_data { struct regmap *regmap; struct device *dev; /* * Protect gain and time during scale adjustment and data reading. * Protect measurement enabling/disabling. */ struct mutex mutex; struct iio_gts gts; struct task_struct *task; __le16 raw[3]; struct { u32 mlux; __le16 channels[3]; s64 ts __aligned(8); } scan; }; struct bu27034_result { u16 ch0; u16 ch1; u16 ch2; }; static const struct regmap_range bu27034_volatile_ranges[] = { { .range_min = BU27034_REG_SYSTEM_CONTROL, .range_max = BU27034_REG_SYSTEM_CONTROL, }, { .range_min = BU27034_REG_MODE_CONTROL4, .range_max = BU27034_REG_MODE_CONTROL4, }, { .range_min = BU27034_REG_DATA0_LO, .range_max = BU27034_REG_DATA2_HI, }, }; static const struct regmap_access_table bu27034_volatile_regs = { .yes_ranges = &bu27034_volatile_ranges[0], .n_yes_ranges = ARRAY_SIZE(bu27034_volatile_ranges), }; static const struct regmap_range bu27034_read_only_ranges[] = { { .range_min = BU27034_REG_DATA0_LO, .range_max = BU27034_REG_DATA2_HI, }, { .range_min = BU27034_REG_MANUFACTURER_ID, .range_max = BU27034_REG_MANUFACTURER_ID, } }; static const struct regmap_access_table bu27034_ro_regs = { .no_ranges = &bu27034_read_only_ranges[0], .n_no_ranges = ARRAY_SIZE(bu27034_read_only_ranges), }; static const struct regmap_config bu27034_regmap = { .reg_bits = 8, .val_bits = 8, .max_register = BU27034_REG_MAX, .cache_type = REGCACHE_RBTREE, .volatile_table = &bu27034_volatile_regs, .wr_table = &bu27034_ro_regs, }; struct bu27034_gain_check { int old_gain; int new_gain; int chan; }; static int bu27034_get_gain_sel(struct bu27034_data *data, int chan) { int ret, val; switch (chan) { case BU27034_CHAN_DATA0: case BU27034_CHAN_DATA1: { int reg[] = { [BU27034_CHAN_DATA0] = BU27034_REG_MODE_CONTROL2, [BU27034_CHAN_DATA1] = BU27034_REG_MODE_CONTROL3, }; ret = regmap_read(data->regmap, reg[chan], &val); if (ret) return ret; return FIELD_GET(BU27034_MASK_D01_GAIN, val); } case BU27034_CHAN_DATA2: { int d2_lo_bits = fls(BU27034_MASK_D2_GAIN_LO); ret = regmap_read(data->regmap, BU27034_REG_MODE_CONTROL2, &val); if (ret) return ret; /* * The data2 channel gain is composed by 5 non continuous bits * [7:6], [2:0]. Thus when we combine the 5-bit 'selector' * from register value we must right shift the high bits by 3. */ return FIELD_GET(BU27034_MASK_D2_GAIN_HI, val) << d2_lo_bits | FIELD_GET(BU27034_MASK_D2_GAIN_LO, val); } default: return -EINVAL; } } static int bu27034_get_gain(struct bu27034_data *data, int chan, int *gain) { int ret, sel; ret = bu27034_get_gain_sel(data, chan); if (ret < 0) return ret; sel = ret; ret = iio_gts_find_gain_by_sel(&data->gts, sel); if (ret < 0) { dev_err(data->dev, "chan %u: unknown gain value 0x%x\n", chan, sel); return ret; } *gain = ret; return 0; } static int bu27034_get_int_time(struct bu27034_data *data) { int ret, sel; ret = regmap_read(data->regmap, BU27034_REG_MODE_CONTROL1, &sel); if (ret) return ret; return iio_gts_find_int_time_by_sel(&data->gts, sel & BU27034_MASK_MEAS_MODE); } static int _bu27034_get_scale(struct bu27034_data *data, int channel, int *val, int *val2) { int gain, ret; ret = bu27034_get_gain(data, channel, &gain); if (ret) return ret; ret = bu27034_get_int_time(data); if (ret < 0) return ret; return iio_gts_get_scale(&data->gts, gain, ret, val, val2); } static int bu27034_get_scale(struct bu27034_data *data, int channel, int *val, int *val2) { int ret; if (channel == BU27034_CHAN_ALS) { *val = 0; *val2 = 1000; return IIO_VAL_INT_PLUS_MICRO; } mutex_lock(&data->mutex); ret = _bu27034_get_scale(data, channel, val, val2); mutex_unlock(&data->mutex); if (ret) return ret; return IIO_VAL_INT_PLUS_NANO; } /* Caller should hold the lock to protect lux reading */ static int bu27034_write_gain_sel(struct bu27034_data *data, int chan, int sel) { static const int reg[] = { [BU27034_CHAN_DATA0] = BU27034_REG_MODE_CONTROL2, [BU27034_CHAN_DATA1] = BU27034_REG_MODE_CONTROL3, }; int mask, val; if (chan != BU27034_CHAN_DATA0 && chan != BU27034_CHAN_DATA1) return -EINVAL; val = FIELD_PREP(BU27034_MASK_D01_GAIN, sel); mask = BU27034_MASK_D01_GAIN; if (chan == BU27034_CHAN_DATA0) { /* * We keep the same gain for channel 2 as we set for channel 0 * We can't allow them to be individually controlled because * setting one will impact also the other. Also, if we don't * always update both gains we may result unsupported bit * combinations. * * This is not nice but this is yet another place where the * user space must be prepared to surprizes. Namely, see chan 2 * gain changed when chan 0 gain is changed. * * This is not fatal for most users though. I don't expect the * channel 2 to be used in any generic cases - the intensity * values provided by the sensor for IR area are not openly * documented. Also, channel 2 is not used for visible light. * * So, if there is application which is written to utilize the * channel 2 - then it is probably specifically targeted to this * sensor and knows how to utilize those values. It is safe to * hope such user can also cope with the gain changes. */ mask |= BU27034_MASK_D2_GAIN_LO; /* * The D2 gain bits are directly the lowest bits of selector. * Just do add those bits to the value */ val |= sel & BU27034_MASK_D2_GAIN_LO; } return regmap_update_bits(data->regmap, reg[chan], mask, val); } static int bu27034_set_gain(struct bu27034_data *data, int chan, int gain) { int ret; /* * We don't allow setting channel 2 gain as it messes up the * gain for channel 0 - which shares the high bits */ if (chan != BU27034_CHAN_DATA0 && chan != BU27034_CHAN_DATA1) return -EINVAL; ret = iio_gts_find_sel_by_gain(&data->gts, gain); if (ret < 0) return ret; return bu27034_write_gain_sel(data, chan, ret); } /* Caller should hold the lock to protect data->int_time */ static int bu27034_set_int_time(struct bu27034_data *data, int time) { int ret; ret = iio_gts_find_sel_by_int_time(&data->gts, time); if (ret < 0) return ret; return regmap_update_bits(data->regmap, BU27034_REG_MODE_CONTROL1, BU27034_MASK_MEAS_MODE, ret); } /* * We try to change the time in such way that the scale is maintained for * given channels by adjusting gain so that it compensates the time change. */ static int bu27034_try_set_int_time(struct bu27034_data *data, int time_us) { struct bu27034_gain_check gains[] = { { .chan = BU27034_CHAN_DATA0 }, { .chan = BU27034_CHAN_DATA1 }, }; int numg = ARRAY_SIZE(gains); int ret, int_time_old, i; mutex_lock(&data->mutex); ret = bu27034_get_int_time(data); if (ret < 0) goto unlock_out; int_time_old = ret; if (!iio_gts_valid_time(&data->gts, time_us)) { dev_err(data->dev, "Unsupported integration time %u\n", time_us); ret = -EINVAL; goto unlock_out; } if (time_us == int_time_old) { ret = 0; goto unlock_out; } for (i = 0; i < numg; i++) { ret = bu27034_get_gain(data, gains[i].chan, &gains[i].old_gain); if (ret) goto unlock_out; ret = iio_gts_find_new_gain_by_old_gain_time(&data->gts, gains[i].old_gain, int_time_old, time_us, &gains[i].new_gain); if (ret) { int scale1, scale2; bool ok; _bu27034_get_scale(data, gains[i].chan, &scale1, &scale2); dev_dbg(data->dev, "chan %u, can't support time %u with scale %u %u\n", gains[i].chan, time_us, scale1, scale2); if (gains[i].new_gain < 0) goto unlock_out; /* * If caller requests for integration time change and we * can't support the scale - then the caller should be * prepared to 'pick up the pieces and deal with the * fact that the scale changed'. */ ret = iio_find_closest_gain_low(&data->gts, gains[i].new_gain, &ok); if (!ok) dev_dbg(data->dev, "optimal gain out of range for chan %u\n", gains[i].chan); if (ret < 0) { dev_dbg(data->dev, "Total gain increase. Risk of saturation"); ret = iio_gts_get_min_gain(&data->gts); if (ret < 0) goto unlock_out; } dev_dbg(data->dev, "chan %u scale changed\n", gains[i].chan); gains[i].new_gain = ret; dev_dbg(data->dev, "chan %u new gain %u\n", gains[i].chan, gains[i].new_gain); } } for (i = 0; i < numg; i++) { ret = bu27034_set_gain(data, gains[i].chan, gains[i].new_gain); if (ret) goto unlock_out; } ret = bu27034_set_int_time(data, time_us); unlock_out: mutex_unlock(&data->mutex); return ret; } static int bu27034_set_scale(struct bu27034_data *data, int chan, int val, int val2) { int ret, time_sel, gain_sel, i; bool found = false; if (chan == BU27034_CHAN_DATA2) return -EINVAL; if (chan == BU27034_CHAN_ALS) { if (val == 0 && val2 == 1000000) return 0; return -EINVAL; } mutex_lock(&data->mutex); ret = regmap_read(data->regmap, BU27034_REG_MODE_CONTROL1, &time_sel); if (ret) goto unlock_out; ret = iio_gts_find_gain_sel_for_scale_using_time(&data->gts, time_sel, val, val2, &gain_sel); if (ret) { /* * Could not support scale with given time. Need to change time. * We still want to maintain the scale for all channels */ struct bu27034_gain_check gain; int new_time_sel; /* * Populate information for the other channel which should also * maintain the scale. (Due to the HW limitations the chan2 * gets the same gain as chan0, so we only need to explicitly * set the chan 0 and 1). */ if (chan == BU27034_CHAN_DATA0) gain.chan = BU27034_CHAN_DATA1; else if (chan == BU27034_CHAN_DATA1) gain.chan = BU27034_CHAN_DATA0; ret = bu27034_get_gain(data, gain.chan, &gain.old_gain); if (ret) goto unlock_out; /* * Iterate through all the times to see if we find one which * can support requested scale for requested channel, while * maintaining the scale for other channels */ for (i = 0; i < data->gts.num_itime; i++) { new_time_sel = data->gts.itime_table[i].sel; if (new_time_sel == time_sel) continue; /* Can we provide requested scale with this time? */ ret = iio_gts_find_gain_sel_for_scale_using_time( &data->gts, new_time_sel, val, val2, &gain_sel); if (ret) continue; /* Can the other channel(s) maintain scale? */ ret = iio_gts_find_new_gain_sel_by_old_gain_time( &data->gts, gain.old_gain, time_sel, new_time_sel, &gain.new_gain); if (!ret) { /* Yes - we found suitable time */ found = true; break; } } if (!found) { dev_dbg(data->dev, "Can't set scale maintaining other channels\n"); ret = -EINVAL; goto unlock_out; } ret = bu27034_set_gain(data, gain.chan, gain.new_gain); if (ret) goto unlock_out; ret = regmap_update_bits(data->regmap, BU27034_REG_MODE_CONTROL1, BU27034_MASK_MEAS_MODE, new_time_sel); if (ret) goto unlock_out; } ret = bu27034_write_gain_sel(data, chan, gain_sel); unlock_out: mutex_unlock(&data->mutex); return ret; } /* * for (D1/D0 < 0.87): * lx = 0.004521097 * D1 - 0.002663996 * D0 + * 0.00012213 * D1 * D1 / D0 * * => 115.7400832 * ch1 / gain1 / mt - * 68.1982976 * ch0 / gain0 / mt + * 0.00012213 * 25600 * (ch1 / gain1 / mt) * 25600 * * (ch1 /gain1 / mt) / (25600 * ch0 / gain0 / mt) * * A = 0.00012213 * 25600 * (ch1 /gain1 / mt) * 25600 * * (ch1 /gain1 / mt) / (25600 * ch0 / gain0 / mt) * => 0.00012213 * 25600 * (ch1 /gain1 / mt) * * (ch1 /gain1 / mt) / (ch0 / gain0 / mt) * => 0.00012213 * 25600 * (ch1 / gain1) * (ch1 /gain1 / mt) / * (ch0 / gain0) * => 0.00012213 * 25600 * (ch1 / gain1) * (ch1 /gain1 / mt) * * gain0 / ch0 * => 3.126528 * ch1 * ch1 * gain0 / gain1 / gain1 / mt /ch0 * * lx = (115.7400832 * ch1 / gain1 - 68.1982976 * ch0 / gain0) / * mt + A * => (115.7400832 * ch1 / gain1 - 68.1982976 * ch0 / gain0) / * mt + 3.126528 * ch1 * ch1 * gain0 / gain1 / gain1 / mt / * ch0 * * => (115.7400832 * ch1 / gain1 - 68.1982976 * ch0 / gain0 + * 3.126528 * ch1 * ch1 * gain0 / gain1 / gain1 / ch0) / * mt * * For (0.87 <= D1/D0 < 1.00) * lx = (0.001331* D0 + 0.0000354 * D1) * ((D1/D0 – 0.87) * (0.385) + 1) * => (0.001331 * 256 * 100 * ch0 / gain0 / mt + 0.0000354 * 256 * * 100 * ch1 / gain1 / mt) * ((D1/D0 - 0.87) * (0.385) + 1) * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) * * ((D1/D0 - 0.87) * (0.385) + 1) * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) * * (0.385 * D1/D0 - 0.66505) * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) * * (0.385 * 256 * 100 * ch1 / gain1 / mt / (256 * 100 * ch0 / gain0 / mt) - 0.66505) * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) * * (9856 * ch1 / gain1 / mt / (25600 * ch0 / gain0 / mt) + 0.66505) * => 13.118336 * ch1 / (gain1 * mt) * + 22.66064768 * ch0 / (gain0 * mt) * + 8931.90144 * ch1 * ch1 * gain0 / * (25600 * ch0 * gain1 * gain1 * mt) * + 0.602694912 * ch1 / (gain1 * mt) * * => [0.3489024 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) * + 22.66064768 * ch0 / gain0 * + 13.721030912 * ch1 / gain1 * ] / mt * * For (D1/D0 >= 1.00) * * lx = (0.001331* D0 + 0.0000354 * D1) * ((D1/D0 – 2.0) * (-0.05) + 1) * => (0.001331* D0 + 0.0000354 * D1) * (-0.05D1/D0 + 1.1) * => (0.001331 * 256 * 100 * ch0 / gain0 / mt + 0.0000354 * 256 * * 100 * ch1 / gain1 / mt) * (-0.05D1/D0 + 1.1) * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) * * (-0.05 * 256 * 100 * ch1 / gain1 / mt / (256 * 100 * ch0 / gain0 / mt) + 1.1) * => (34.0736 * ch0 / gain0 / mt + 0.90624 * ch1 / gain1 / mt) * * (-1280 * ch1 / (gain1 * mt * 25600 * ch0 / gain0 / mt) + 1.1) * => (34.0736 * ch0 * -1280 * ch1 * gain0 * mt /( gain0 * mt * gain1 * mt * 25600 * ch0) * + 34.0736 * 1.1 * ch0 / (gain0 * mt) * + 0.90624 * ch1 * -1280 * ch1 *gain0 * mt / (gain1 * mt *gain1 * mt * 25600 * ch0) * + 1.1 * 0.90624 * ch1 / (gain1 * mt) * => -43614.208 * ch1 / (gain1 * mt * 25600) * + 37.48096 ch0 / (gain0 * mt) * - 1159.9872 * ch1 * ch1 * gain0 / (gain1 * gain1 * mt * 25600 * ch0) * + 0.996864 ch1 / (gain1 * mt) * => [ * - 0.045312 * ch1 * ch1 * gain0 / (gain1 * gain1 * ch0) * - 0.706816 * ch1 / gain1 * + 37.48096 ch0 /gain0 * ] * mt * * * So, the first case (D1/D0 < 0.87) can be computed to a form: * * lx = (3.126528 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) + * 115.7400832 * ch1 / gain1 + * -68.1982976 * ch0 / gain0 * / mt * * Second case (0.87 <= D1/D0 < 1.00) goes to form: * * => [0.3489024 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) + * 13.721030912 * ch1 / gain1 + * 22.66064768 * ch0 / gain0 * ] / mt * * Third case (D1/D0 >= 1.00) goes to form: * => [-0.045312 * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) + * -0.706816 * ch1 / gain1 + * 37.48096 ch0 /(gain0 * ] / mt * * This can be unified to format: * lx = [ * A * ch1 * ch1 * gain0 / (ch0 * gain1 * gain1) + * B * ch1 / gain1 + * C * ch0 / gain0 * ] / mt * * For case 1: * A = 3.126528, * B = 115.7400832 * C = -68.1982976 * * For case 2: * A = 0.3489024 * B = 13.721030912 * C = 22.66064768 * * For case 3: * A = -0.045312 * B = -0.706816 * C = 37.48096 */ struct bu27034_lx_coeff { unsigned int A; unsigned int B; unsigned int C; /* Indicate which of the coefficients above are negative */ bool is_neg[3]; }; static inline u64 gain_mul_div_helper(u64 val, unsigned int gain, unsigned int div) { /* * Max gain for a channel is 4096. The max u64 (0xffffffffffffffffULL) * divided by 4096 is 0xFFFFFFFFFFFFF (GENMASK_ULL(51, 0)) (floored). * Thus, the 0xFFFFFFFFFFFFF is the largest value we can safely multiply * with the gain, no matter what gain is set. * * So, multiplication with max gain may overflow if val is greater than * 0xFFFFFFFFFFFFF (52 bits set).. * * If this is the case we divide first. */ if (val < GENMASK_ULL(51, 0)) { val *= gain; do_div(val, div); } else { do_div(val, div); val *= gain; } return val; } static u64 bu27034_fixp_calc_t1_64bit(unsigned int coeff, unsigned int ch0, unsigned int ch1, unsigned int gain0, unsigned int gain1) { unsigned int helper; u64 helper64; helper64 = (u64)coeff * (u64)ch1 * (u64)ch1; helper = gain1 * gain1; if (helper > ch0) { do_div(helper64, helper); return gain_mul_div_helper(helper64, gain0, ch0); } do_div(helper64, ch0); return gain_mul_div_helper(helper64, gain0, helper); } static u64 bu27034_fixp_calc_t1(unsigned int coeff, unsigned int ch0, unsigned int ch1, unsigned int gain0, unsigned int gain1) { unsigned int helper, tmp; /* * Here we could overflow even the 64bit value. Hence we * multiply with gain0 only after the divisions - even though * it may result loss of accuracy */ helper = coeff * ch1 * ch1; tmp = helper * gain0; helper = ch1 * ch1; if (check_mul_overflow(helper, coeff, &helper)) return bu27034_fixp_calc_t1_64bit(coeff, ch0, ch1, gain0, gain1); if (check_mul_overflow(helper, gain0, &tmp)) return bu27034_fixp_calc_t1_64bit(coeff, ch0, ch1, gain0, gain1); return tmp / (gain1 * gain1) / ch0; } static u64 bu27034_fixp_calc_t23(unsigned int coeff, unsigned int ch, unsigned int gain) { unsigned int helper; u64 helper64; if (!check_mul_overflow(coeff, ch, &helper)) return helper / gain; helper64 = (u64)coeff * (u64)ch; do_div(helper64, gain); return helper64; } static int bu27034_fixp_calc_lx(unsigned int ch0, unsigned int ch1, unsigned int gain0, unsigned int gain1, unsigned int meastime, int coeff_idx) { static const struct bu27034_lx_coeff coeff[] = { { .A = 31265280, /* 3.126528 */ .B = 1157400832, /*115.7400832 */ .C = 681982976, /* -68.1982976 */ .is_neg = {false, false, true}, }, { .A = 3489024, /* 0.3489024 */ .B = 137210309, /* 13.721030912 */ .C = 226606476, /* 22.66064768 */ /* All terms positive */ }, { .A = 453120, /* -0.045312 */ .B = 7068160, /* -0.706816 */ .C = 374809600, /* 37.48096 */ .is_neg = {true, true, false}, } }; const struct bu27034_lx_coeff *c = &coeff[coeff_idx]; u64 res = 0, terms[3]; int i; if (coeff_idx >= ARRAY_SIZE(coeff)) return -EINVAL; terms[0] = bu27034_fixp_calc_t1(c->A, ch0, ch1, gain0, gain1); terms[1] = bu27034_fixp_calc_t23(c->B, ch1, gain1); terms[2] = bu27034_fixp_calc_t23(c->C, ch0, gain0); /* First, add positive terms */ for (i = 0; i < 3; i++) if (!c->is_neg[i]) res += terms[i]; /* No positive term => zero lux */ if (!res) return 0; /* Then, subtract negative terms (if any) */ for (i = 0; i < 3; i++) if (c->is_neg[i]) { /* * If the negative term is greater than positive - then * the darkness has taken over and we are all doomed! Eh, * I mean, then we can just return 0 lx and go out */ if (terms[i] >= res) return 0; res -= terms[i]; } meastime *= 10; do_div(res, meastime); return (int) res; } static bool bu27034_has_valid_sample(struct bu27034_data *data) { int ret, val; ret = regmap_read(data->regmap, BU27034_REG_MODE_CONTROL4, &val); if (ret) { dev_err(data->dev, "Read failed %d\n", ret); return false; } return val & BU27034_MASK_VALID; } /* * Reading the register where VALID bit is clears this bit. (So does changing * any gain / integration time configuration registers) The bit gets * set when we have acquired new data. We use this bit to indicate data * validity. */ static void bu27034_invalidate_read_data(struct bu27034_data *data) { bu27034_has_valid_sample(data); } static int bu27034_read_result(struct bu27034_data *data, int chan, int *res) { int reg[] = { [BU27034_CHAN_DATA0] = BU27034_REG_DATA0_LO, [BU27034_CHAN_DATA1] = BU27034_REG_DATA1_LO, [BU27034_CHAN_DATA2] = BU27034_REG_DATA2_LO, }; int valid, ret; __le16 val; ret = regmap_read_poll_timeout(data->regmap, BU27034_REG_MODE_CONTROL4, valid, (valid & BU27034_MASK_VALID), BU27034_DATA_WAIT_TIME_US, 0); if (ret) return ret; ret = regmap_bulk_read(data->regmap, reg[chan], &val, sizeof(val)); if (ret) return ret; *res = le16_to_cpu(val); return 0; } static int bu27034_get_result_unlocked(struct bu27034_data *data, __le16 *res, int size) { int ret = 0, retry_cnt = 0; retry: /* Get new value from sensor if data is ready */ if (bu27034_has_valid_sample(data)) { ret = regmap_bulk_read(data->regmap, BU27034_REG_DATA0_LO, res, size); if (ret) return ret; bu27034_invalidate_read_data(data); } else { /* No new data in sensor. Wait and retry */ retry_cnt++; if (retry_cnt > BU27034_RETRY_LIMIT) { dev_err(data->dev, "No data from sensor\n"); return -ETIMEDOUT; } msleep(25); goto retry; } return ret; } static int bu27034_meas_set(struct bu27034_data *data, bool en) { if (en) return regmap_set_bits(data->regmap, BU27034_REG_MODE_CONTROL4, BU27034_MASK_MEAS_EN); return regmap_clear_bits(data->regmap, BU27034_REG_MODE_CONTROL4, BU27034_MASK_MEAS_EN); } static int bu27034_get_single_result(struct bu27034_data *data, int chan, int *val) { int ret; if (chan < BU27034_CHAN_DATA0 || chan > BU27034_CHAN_DATA2) return -EINVAL; ret = bu27034_meas_set(data, true); if (ret) return ret; ret = bu27034_get_int_time(data); if (ret < 0) return ret; msleep(ret / 1000); return bu27034_read_result(data, chan, val); } /* * The formula given by vendor for computing luxes out of data0 and data1 * (in open air) is as follows: * * Let's mark: * D0 = data0/ch0_gain/meas_time_ms * 25600 * D1 = data1/ch1_gain/meas_time_ms * 25600 * * Then: * if (D1/D0 < 0.87) * lx = (0.001331 * D0 + 0.0000354 * D1) * ((D1 / D0 - 0.87) * 3.45 + 1) * else if (D1/D0 < 1) * lx = (0.001331 * D0 + 0.0000354 * D1) * ((D1 / D0 - 0.87) * 0.385 + 1) * else * lx = (0.001331 * D0 + 0.0000354 * D1) * ((D1 / D0 - 2) * -0.05 + 1) * * We use it here. Users who have for example some colored lens * need to modify the calculation but I hope this gives a starting point for * those working with such devices. */ static int bu27034_calc_mlux(struct bu27034_data *data, __le16 *res, int *val) { unsigned int gain0, gain1, meastime; unsigned int d1_d0_ratio_scaled; u16 ch0, ch1; u64 helper64; int ret; /* * We return 0 lux if calculation fails. This should be reasonably * easy to spot from the buffers especially if raw-data channels show * valid values */ *val = 0; ch0 = max_t(u16, 1, le16_to_cpu(res[0])); ch1 = max_t(u16, 1, le16_to_cpu(res[1])); ret = bu27034_get_gain(data, BU27034_CHAN_DATA0, &gain0); if (ret) return ret; ret = bu27034_get_gain(data, BU27034_CHAN_DATA1, &gain1); if (ret) return ret; ret = bu27034_get_int_time(data); if (ret < 0) return ret; meastime = ret; d1_d0_ratio_scaled = (unsigned int)ch1 * (unsigned int)gain0 * 100; helper64 = (u64)ch1 * (u64)gain0 * 100LLU; if (helper64 != d1_d0_ratio_scaled) { unsigned int div = (unsigned int)ch0 * gain1; do_div(helper64, div); d1_d0_ratio_scaled = helper64; } else { d1_d0_ratio_scaled /= ch0 * gain1; } if (d1_d0_ratio_scaled < 87) ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 0); else if (d1_d0_ratio_scaled < 100) ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 1); else ret = bu27034_fixp_calc_lx(ch0, ch1, gain0, gain1, meastime, 2); if (ret < 0) return ret; *val = ret; return 0; } static int bu27034_get_mlux(struct bu27034_data *data, int chan, int *val) { __le16 res[3]; int ret; ret = bu27034_meas_set(data, true); if (ret) return ret; ret = bu27034_get_result_unlocked(data, &res[0], sizeof(res)); if (ret) return ret; ret = bu27034_calc_mlux(data, res, val); if (ret) return ret; ret = bu27034_meas_set(data, false); if (ret) dev_err(data->dev, "failed to disable measurement\n"); return 0; } static int bu27034_read_raw(struct iio_dev *idev, struct iio_chan_spec const *chan, int *val, int *val2, long mask) { struct bu27034_data *data = iio_priv(idev); int ret; switch (mask) { case IIO_CHAN_INFO_INT_TIME: *val = 0; *val2 = bu27034_get_int_time(data); if (*val2 < 0) return *val2; return IIO_VAL_INT_PLUS_MICRO; case IIO_CHAN_INFO_SCALE: return bu27034_get_scale(data, chan->channel, val, val2); case IIO_CHAN_INFO_RAW: { int (*result_get)(struct bu27034_data *data, int chan, int *val); if (chan->type == IIO_INTENSITY) result_get = bu27034_get_single_result; else if (chan->type == IIO_LIGHT) result_get = bu27034_get_mlux; else return -EINVAL; /* Don't mess with measurement enabling while buffering */ ret = iio_device_claim_direct_mode(idev); if (ret) return ret; mutex_lock(&data->mutex); /* * Reading one channel at a time is inefficient but we * don't care here. Buffered version should be used if * performance is an issue. */ ret = result_get(data, chan->channel, val); mutex_unlock(&data->mutex); iio_device_release_direct_mode(idev); if (ret) return ret; return IIO_VAL_INT; } default: return -EINVAL; } } static int bu27034_write_raw_get_fmt(struct iio_dev *indio_dev, struct iio_chan_spec const *chan, long mask) { switch (mask) { case IIO_CHAN_INFO_SCALE: return IIO_VAL_INT_PLUS_NANO; case IIO_CHAN_INFO_INT_TIME: return IIO_VAL_INT_PLUS_MICRO; default: return -EINVAL; } } static int bu27034_write_raw(struct iio_dev *idev, struct iio_chan_spec const *chan, int val, int val2, long mask) { struct bu27034_data *data = iio_priv(idev); int ret; ret = iio_device_claim_direct_mode(idev); if (ret) return ret; switch (mask) { case IIO_CHAN_INFO_SCALE: ret = bu27034_set_scale(data, chan->channel, val, val2); break; case IIO_CHAN_INFO_INT_TIME: if (!val) ret = bu27034_try_set_int_time(data, val2); else ret = -EINVAL; break; default: ret = -EINVAL; break; } iio_device_release_direct_mode(idev); return ret; } static int bu27034_read_avail(struct iio_dev *idev, struct iio_chan_spec const *chan, const int **vals, int *type, int *length, long mask) { struct bu27034_data *data = iio_priv(idev); switch (mask) { case IIO_CHAN_INFO_INT_TIME: return iio_gts_avail_times(&data->gts, vals, type, length); case IIO_CHAN_INFO_SCALE: return iio_gts_all_avail_scales(&data->gts, vals, type, length); default: return -EINVAL; } } static const struct iio_info bu27034_info = { .read_raw = &bu27034_read_raw, .write_raw = &bu27034_write_raw, .write_raw_get_fmt = &bu27034_write_raw_get_fmt, .read_avail = &bu27034_read_avail, }; static int bu27034_chip_init(struct bu27034_data *data) { int ret, sel; /* Reset */ ret = regmap_write_bits(data->regmap, BU27034_REG_SYSTEM_CONTROL, BU27034_MASK_SW_RESET, BU27034_MASK_SW_RESET); if (ret) return dev_err_probe(data->dev, ret, "Sensor reset failed\n"); msleep(1); ret = regmap_reinit_cache(data->regmap, &bu27034_regmap); if (ret) { dev_err(data->dev, "Failed to reinit reg cache\n"); return ret; } /* * Read integration time here to ensure it is in regmap cache. We do * this to speed-up the int-time acquisition in the start of the buffer * handling thread where longer delays could make it more likely we end * up skipping a sample, and where the longer delays make timestamps * less accurate. */ ret = regmap_read(data->regmap, BU27034_REG_MODE_CONTROL1, &sel); if (ret) dev_err(data->dev, "reading integration time failed\n"); return 0; } static int bu27034_wait_for_data(struct bu27034_data *data) { int ret, val; ret = regmap_read_poll_timeout(data->regmap, BU27034_REG_MODE_CONTROL4, val, val & BU27034_MASK_VALID, BU27034_DATA_WAIT_TIME_US, BU27034_TOTAL_DATA_WAIT_TIME_US); if (ret) { dev_err(data->dev, "data polling %s\n", !(val & BU27034_MASK_VALID) ? "timeout" : "fail"); return ret; } ret = regmap_bulk_read(data->regmap, BU27034_REG_DATA0_LO, &data->scan.channels[0], sizeof(data->scan.channels)); if (ret) return ret; bu27034_invalidate_read_data(data); return 0; } static int bu27034_buffer_thread(void *arg) { struct iio_dev *idev = arg; struct bu27034_data *data; int wait_ms; data = iio_priv(idev); wait_ms = bu27034_get_int_time(data); wait_ms /= 1000; wait_ms -= BU27034_MEAS_WAIT_PREMATURE_MS; while (!kthread_should_stop()) { int ret; int64_t tstamp; msleep(wait_ms); ret = bu27034_wait_for_data(data); if (ret) continue; tstamp = iio_get_time_ns(idev); if (test_bit(BU27034_CHAN_ALS, idev->active_scan_mask)) { int mlux; ret = bu27034_calc_mlux(data, &data->scan.channels[0], &mlux); if (ret) dev_err(data->dev, "failed to calculate lux\n"); /* * The maximum Milli lux value we get with gain 1x time * 55mS data ch0 = 0xffff ch1 = 0xffff fits in 26 bits * so there should be no problem returning int from * computations and casting it to u32 */ data->scan.mlux = (u32)mlux; } iio_push_to_buffers_with_timestamp(idev, &data->scan, tstamp); } return 0; } static int bu27034_buffer_enable(struct iio_dev *idev) { struct bu27034_data *data = iio_priv(idev); struct task_struct *task; int ret; mutex_lock(&data->mutex); ret = bu27034_meas_set(data, true); if (ret) goto unlock_out; task = kthread_run(bu27034_buffer_thread, idev, "bu27034-buffering-%u", iio_device_id(idev)); if (IS_ERR(task)) { ret = PTR_ERR(task); goto unlock_out; } data->task = task; unlock_out: mutex_unlock(&data->mutex); return ret; } static int bu27034_buffer_disable(struct iio_dev *idev) { struct bu27034_data *data = iio_priv(idev); int ret; mutex_lock(&data->mutex); if (data->task) { kthread_stop(data->task); data->task = NULL; } ret = bu27034_meas_set(data, false); mutex_unlock(&data->mutex); return ret; } static const struct iio_buffer_setup_ops bu27034_buffer_ops = { .postenable = &bu27034_buffer_enable, .predisable = &bu27034_buffer_disable, }; static int bu27034_probe(struct i2c_client *i2c) { struct device *dev = &i2c->dev; struct bu27034_data *data; struct regmap *regmap; struct iio_dev *idev; unsigned int part_id, reg; int ret; regmap = devm_regmap_init_i2c(i2c, &bu27034_regmap); if (IS_ERR(regmap)) return dev_err_probe(dev, PTR_ERR(regmap), "Failed to initialize Regmap\n"); idev = devm_iio_device_alloc(dev, sizeof(*data)); if (!idev) return -ENOMEM; ret = devm_regulator_get_enable(dev, "vdd"); if (ret) return dev_err_probe(dev, ret, "Failed to get regulator\n"); data = iio_priv(idev); ret = regmap_read(regmap, BU27034_REG_SYSTEM_CONTROL, ®); if (ret) return dev_err_probe(dev, ret, "Failed to access sensor\n"); part_id = FIELD_GET(BU27034_MASK_PART_ID, reg); if (part_id != BU27034_ID) dev_warn(dev, "unknown device 0x%x\n", part_id); ret = devm_iio_init_iio_gts(dev, BU27034_SCALE_1X, 0, bu27034_gains, ARRAY_SIZE(bu27034_gains), bu27034_itimes, ARRAY_SIZE(bu27034_itimes), &data->gts); if (ret) return ret; mutex_init(&data->mutex); data->regmap = regmap; data->dev = dev; idev->channels = bu27034_channels; idev->num_channels = ARRAY_SIZE(bu27034_channels); idev->name = "bu27034"; idev->info = &bu27034_info; idev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE; idev->available_scan_masks = bu27034_scan_masks; ret = bu27034_chip_init(data); if (ret) return ret; ret = devm_iio_kfifo_buffer_setup(dev, idev, &bu27034_buffer_ops); if (ret) return dev_err_probe(dev, ret, "buffer setup failed\n"); ret = devm_iio_device_register(dev, idev); if (ret < 0) return dev_err_probe(dev, ret, "Unable to register iio device\n"); return ret; } static const struct of_device_id bu27034_of_match[] = { { .compatible = "rohm,bu27034" }, { } }; MODULE_DEVICE_TABLE(of, bu27034_of_match); static struct i2c_driver bu27034_i2c_driver = { .driver = { .name = "bu27034-als", .of_match_table = bu27034_of_match, .probe_type = PROBE_PREFER_ASYNCHRONOUS, }, .probe = bu27034_probe, }; module_i2c_driver(bu27034_i2c_driver); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>"); MODULE_DESCRIPTION("ROHM BU27034 ambient light sensor driver"); MODULE_IMPORT_NS(IIO_GTS_HELPER); |