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Message-ID: <da7e6b31a0f25106d7e2f56fb089c8fe71224654.1754559149.git.mazziesaccount@gmail.com>
Date: Thu, 7 Aug 2025 12:35:25 +0300
From: Matti Vaittinen <mazziesaccount@...il.com>
To: Matti Vaittinen <mazziesaccount@...il.com>,
Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
Cc: Lars-Peter Clausen <lars@...afoo.de>,
Michael Hennerich <Michael.Hennerich@...log.com>,
Jonathan Cameron <jic23@...nel.org>,
David Lechner <dlechner@...libre.com>,
Nuno Sá <nuno.sa@...log.com>,
Andy Shevchenko <andy@...nel.org>, Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>,
Matti Vaittinen <mazziesaccount@...il.com>,
Liam Girdwood <lgirdwood@...il.com>,
Mark Brown <broonie@...nel.org>, linux-iio@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 09/10] iio: adc: ad7476: Support ROHM BD79105
The ROHM BD79105 is a simple 16-bit ADC accessible via SPI*.
The BD79105 has a CONVSTART pin, which must be set high to start the ADC
conversion. Unlike with the ad7091 and ad7091r which also have a
CONVSTART pin, the BD79105 requires that the pin must remain high also
for the duration of the SPI access.
(*) Couple of words about the SPI. The BD79105 has pins named as
CONVSTART, SCLK, DIN and DOUT. For the curious reader, DIN is not SPI
ISO.
DIN is a signal which can be used as a chip-select. When DIN is pulled
low, the ADC will output the completed measurement via DOUT as SCLK is
clocked. According to the data-sheet, the DIN can also be used for
daisy-chaining multiple ADCs. Furthermore, DOUT can be used also for a
'data-ready' -IRQ. These modes aren't supported by this driver.
Support reading ADC scale and data from the BD79105 using SPI, when DIN
is used as a chip-select.
Signed-off-by: Matti Vaittinen <mazziesaccount@...il.com>
---
Revision history:
v1 => v2:
- Fix the conversion delay for the BD79105
- Drop unnecessary GPIO check from the convstart disable
- Drop unintended whitespace change
- Fix spelling
---
drivers/iio/adc/ad7476.c | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
index 8914861802be..aa8a522633eb 100644
--- a/drivers/iio/adc/ad7476.c
+++ b/drivers/iio/adc/ad7476.c
@@ -31,6 +31,7 @@ struct ad7476_chip_info {
struct iio_chan_spec channel[2];
void (*reset)(struct ad7476_state *);
void (*conversion_pre_op)(struct ad7476_state *st);
+ void (*conversion_post_op)(struct ad7476_state *st);
bool has_vref;
bool has_vdrive;
};
@@ -39,6 +40,7 @@ struct ad7476_state {
struct spi_device *spi;
struct gpio_desc *convst_gpio;
void (*conversion_pre_op)(struct ad7476_state *st);
+ void (*conversion_post_op)(struct ad7476_state *st);
struct spi_transfer xfer;
struct spi_message msg;
struct iio_chan_spec channel[2];
@@ -63,6 +65,21 @@ static void ad7091_convst(struct ad7476_state *st)
udelay(1); /* Conversion time: 650 ns max */
}
+static void bd79105_convst_disable(struct ad7476_state *st)
+{
+ gpiod_set_value(st->convst_gpio, 0);
+}
+
+static void bd79105_convst_enable(struct ad7476_state *st)
+{
+ if (!st->convst_gpio)
+ return;
+
+ gpiod_set_value(st->convst_gpio, 1);
+ /* Worst case, 2790 nS required for conversion */
+ ndelay(2790);
+}
+
static irqreturn_t ad7476_trigger_handler(int irq, void *p)
{
struct iio_poll_func *pf = p;
@@ -80,6 +97,8 @@ static irqreturn_t ad7476_trigger_handler(int irq, void *p)
iio_push_to_buffers_with_ts(indio_dev, st->data, sizeof(st->data),
iio_get_time_ns(indio_dev));
done:
+ if (st->conversion_post_op)
+ st->conversion_post_op(st);
iio_trigger_notify_done(indio_dev->trig);
return IRQ_HANDLED;
@@ -271,6 +290,20 @@ static const struct ad7476_chip_info ltc2314_14_chip_info = {
.has_vref = true,
};
+static const struct ad7476_chip_info bd79105_chip_info = {
+ .channel[0] = AD7091R_CHAN(16),
+ .channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+ /*
+ * The BD79105 starts ADC data conversion when the CONVSTART line is
+ * set HIGH. The CONVSTART must be kept HIGH until the data has been
+ * read from the ADC.
+ */
+ .conversion_pre_op = bd79105_convst_enable,
+ .conversion_post_op = bd79105_convst_disable,
+ .has_vref = true,
+ .has_vdrive = true,
+};
+
static const struct iio_info ad7476_info = {
.read_raw = &ad7476_read_raw,
};
@@ -325,6 +358,7 @@ static int ad7476_probe(struct spi_device *spi)
}
st->conversion_pre_op = chip_info->conversion_pre_op;
+ st->conversion_post_op = chip_info->conversion_post_op;
st->convst_gpio = devm_gpiod_get_optional(&spi->dev,
"adi,conversion-start",
GPIOD_OUT_LOW);
@@ -400,6 +434,7 @@ static const struct spi_device_id ad7476_id[] = {
{ "ads7866", (kernel_ulong_t)&ads7866_chip_info },
{ "ads7867", (kernel_ulong_t)&ads7867_chip_info },
{ "ads7868", (kernel_ulong_t)&ads7868_chip_info },
+ { "bd79105", (kernel_ulong_t)&bd79105_chip_info },
/*
* The ROHM BU79100G is identical to the TI's ADS7866 from the software
* point of view. The binding document mandates the ADS7866 to be
--
2.50.1
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