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Message-ID: <6ee06d551256db9213ccbe72f44cfe9452717716.1754901948.git.mazziesaccount@gmail.com>
Date: Mon, 11 Aug 2025 11:52:22 +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 v4 10/11] 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>
Reviewed-by: Nuno Sá <nuno.sa@...log.com>
Reviewed-by: Andy Shevchenko <andy@...nel.org>
---
Revision history:
v3 => :
- No changes
v2 => v3:
- Check for missing convstart GPIO at probe.
- Use indirect call to convstart (via function pointer) also from the
ad7476_scan_direct().
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 | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
index 6cb2cbeafbd3..1bec6657394c 100644
--- a/drivers/iio/adc/ad7476.c
+++ b/drivers/iio/adc/ad7476.c
@@ -32,8 +32,10 @@ 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;
+ bool convstart_required;
};
struct ad7476_state {
@@ -64,6 +66,18 @@ 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_cansleep(st->convst_gpio, 0);
+}
+
+static void bd79105_convst_enable(struct ad7476_state *st)
+{
+ gpiod_set_value_cansleep(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;
@@ -81,6 +95,8 @@ 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->chip_info->conversion_post_op)
+ st->chip_info->conversion_post_op(st);
iio_trigger_notify_done(indio_dev->trig);
return IRQ_HANDLED;
@@ -103,6 +119,9 @@ static int ad7476_scan_direct(struct ad7476_state *st)
if (ret)
return ret;
+ if (st->chip_info->conversion_post_op)
+ st->chip_info->conversion_post_op(st);
+
return be16_to_cpup((__be16 *)st->data);
}
@@ -273,6 +292,22 @@ 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,
+ /* BD79105 won't do conversion without convstart */
+ .convstart_required = true,
+ .has_vref = true,
+ .has_vdrive = true,
+};
+
static const struct iio_info ad7476_info = {
.read_raw = &ad7476_read_raw,
};
@@ -332,6 +367,9 @@ static int ad7476_probe(struct spi_device *spi)
if (IS_ERR(st->convst_gpio))
return PTR_ERR(st->convst_gpio);
+ if (st->chip_info->convstart_required && !st->convst_gpio)
+ return dev_err_probe(&spi->dev, -EINVAL, "No convstart GPIO\n");
+
/*
* This will never happen. Unless someone changes the channel specs
* in this driver. And if someone does, without changing the loop
@@ -401,6 +439,7 @@ 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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