From 6b104e7895ab16b9b7f466c5f2ca282b87f661e8 Mon Sep 17 00:00:00 2001 From: Florian Boor Date: Thu, 30 Sep 2021 12:42:48 +0200 Subject: [PATCH] iio: adc: ad799x: Implement selecting external reference voltage input on AD7991, AD7995 and AD7999. Make use of the AD7991_REF_SEL bit and support using the external reference voltage if 'vref-supply' is present. Use VCC voltage supply as reference if no extra reference is supplied. Signed-off-by: Florian Boor Link: https://lore.kernel.org/r/20210930104249.2924336-1-florian.boor@kernelconcepts.de Signed-off-by: Jonathan Cameron --- drivers/iio/adc/ad799x.c | 68 ++++++++++++++++++++++++++++++---------- 1 file changed, 51 insertions(+), 17 deletions(-) diff --git a/drivers/iio/adc/ad799x.c b/drivers/iio/adc/ad799x.c index 18bf8386d50a..220228c375d3 100644 --- a/drivers/iio/adc/ad799x.c +++ b/drivers/iio/adc/ad799x.c @@ -299,7 +299,11 @@ static int ad799x_read_raw(struct iio_dev *indio_dev, GENMASK(chan->scan_type.realbits - 1, 0); return IIO_VAL_INT; case IIO_CHAN_INFO_SCALE: - ret = regulator_get_voltage(st->vref); + if (st->vref) + ret = regulator_get_voltage(st->vref); + else + ret = regulator_get_voltage(st->reg); + if (ret < 0) return ret; *val = ret / 1000; @@ -770,6 +774,7 @@ static int ad799x_probe(struct i2c_client *client, const struct i2c_device_id *id) { int ret; + int extra_config = 0; struct ad799x_state *st; struct iio_dev *indio_dev; const struct ad799x_chip_info *chip_info = @@ -797,14 +802,36 @@ static int ad799x_probe(struct i2c_client *client, ret = regulator_enable(st->reg); if (ret) return ret; - st->vref = devm_regulator_get(&client->dev, "vref"); + + /* check if an external reference is supplied */ + st->vref = devm_regulator_get_optional(&client->dev, "vref"); + if (IS_ERR(st->vref)) { - ret = PTR_ERR(st->vref); - goto error_disable_reg; + if (PTR_ERR(st->vref) == -ENODEV) { + st->vref = NULL; + dev_info(&client->dev, "Using VCC reference voltage\n"); + } else { + ret = PTR_ERR(st->vref); + goto error_disable_reg; + } + } + + if (st->vref) { + /* + * Use external reference voltage if supported by hardware. + * This is optional if voltage / regulator present, use VCC otherwise. + */ + if ((st->id == ad7991) || (st->id == ad7995) || (st->id == ad7999)) { + dev_info(&client->dev, "Using external reference voltage\n"); + extra_config |= AD7991_REF_SEL; + ret = regulator_enable(st->vref); + if (ret) + goto error_disable_reg; + } else { + st->vref = NULL; + dev_warn(&client->dev, "Supplied reference not supported\n"); + } } - ret = regulator_enable(st->vref); - if (ret) - goto error_disable_reg; st->client = client; @@ -815,7 +842,7 @@ static int ad799x_probe(struct i2c_client *client, indio_dev->channels = st->chip_config->channel; indio_dev->num_channels = chip_info->num_channels; - ret = ad799x_update_config(st, st->chip_config->default_config); + ret = ad799x_update_config(st, st->chip_config->default_config | extra_config); if (ret) goto error_disable_vref; @@ -845,7 +872,8 @@ static int ad799x_probe(struct i2c_client *client, error_cleanup_ring: iio_triggered_buffer_cleanup(indio_dev); error_disable_vref: - regulator_disable(st->vref); + if (st->vref) + regulator_disable(st->vref); error_disable_reg: regulator_disable(st->reg); @@ -860,7 +888,8 @@ static int ad799x_remove(struct i2c_client *client) iio_device_unregister(indio_dev); iio_triggered_buffer_cleanup(indio_dev); - regulator_disable(st->vref); + if (st->vref) + regulator_disable(st->vref); regulator_disable(st->reg); kfree(st->rx_buf); @@ -872,7 +901,8 @@ static int __maybe_unused ad799x_suspend(struct device *dev) struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev)); struct ad799x_state *st = iio_priv(indio_dev); - regulator_disable(st->vref); + if (st->vref) + regulator_disable(st->vref); regulator_disable(st->reg); return 0; @@ -889,17 +919,21 @@ static int __maybe_unused ad799x_resume(struct device *dev) dev_err(dev, "Unable to enable vcc regulator\n"); return ret; } - ret = regulator_enable(st->vref); - if (ret) { - regulator_disable(st->reg); - dev_err(dev, "Unable to enable vref regulator\n"); - return ret; + + if (st->vref) { + ret = regulator_enable(st->vref); + if (ret) { + regulator_disable(st->reg); + dev_err(dev, "Unable to enable vref regulator\n"); + return ret; + } } /* resync config */ ret = ad799x_update_config(st, st->config); if (ret) { - regulator_disable(st->vref); + if (st->vref) + regulator_disable(st->vref); regulator_disable(st->reg); return ret; }