[PATCH v4 07/11] iio: adc: ad7476: Conditionally call convstart

[Matti Vaittinen <mazziesaccount@gmail.com>]

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The ad7476 supports two IC variants which may have a 'convstart' -GPIO
for starting the conversion. Currently the driver calls a function which
tries to access the GPIO for all of the IC variants, whether they
support 'convstart' or not. This is not an error because this function
returns early if GPIO information is not populated.

We can do a tad better by calling this function only for the ICs which
have the 'convstart' by providing a function pointer to the convstart
function from the chip_info structure, and calling this function only
for the ICs which have the function pointer set.

This does also allow to support ICs which require different convstart
handling than the currently supported ICs.

Call convstart function only on the ICs which can support it and allow
IC-specific convstart functions for the ICs which require different
handling.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>

---
Revision history:
 v3 => :
 - No changes

 v2 => v3:
 - Use indirect call to convstart (via function pointer) also from the
   ad7476_scan_direct().
 - Adapt to the change which returned the chip_info pointer back to the
   driver's state structure.

 v1 => v2:
 - Adapt to the change which removed the chip_info pointer from the
  driver's state structure.

The follow-up patch adding support for the ROHM BD79105 will bring
different 'convstart' functions in use. The IC specific pointer will
also prepare the way for this.
---
 drivers/iio/adc/ad7476.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
index ad9e629f0cbd..6cb2cbeafbd3 100644
--- a/drivers/iio/adc/ad7476.c
+++ b/drivers/iio/adc/ad7476.c
@@ -31,6 +31,7 @@ struct ad7476_chip_info {
 	unsigned int			int_vref_mv;
 	struct iio_chan_spec		channel[2];
 	void (*reset)(struct ad7476_state *);
+	void (*conversion_pre_op)(struct ad7476_state *st);
 	bool				has_vref;
 	bool				has_vdrive;
 };
@@ -70,7 +71,8 @@ static irqreturn_t ad7476_trigger_handler(int irq, void  *p)
 	struct ad7476_state *st = iio_priv(indio_dev);
 	int b_sent;
 
-	ad7091_convst(st);
+	if (st->chip_info->conversion_pre_op)
+		st->chip_info->conversion_pre_op(st);
 
 	b_sent = spi_sync(st->spi, &st->msg);
 	if (b_sent < 0)
@@ -94,7 +96,8 @@ static int ad7476_scan_direct(struct ad7476_state *st)
 {
 	int ret;
 
-	ad7091_convst(st);
+	if (st->chip_info->conversion_pre_op)
+		st->chip_info->conversion_pre_op(st);
 
 	ret = spi_sync(st->spi, &st->msg);
 	if (ret)
@@ -160,12 +163,14 @@ static int ad7476_read_raw(struct iio_dev *indio_dev,
 static const struct ad7476_chip_info ad7091_chip_info = {
 	.channel[0] = AD7091R_CHAN(12),
 	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+	.conversion_pre_op = ad7091_convst,
 	.reset = ad7091_reset,
 };
 
 static const struct ad7476_chip_info ad7091r_chip_info = {
 	.channel[0] = AD7091R_CHAN(12),
 	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+	.conversion_pre_op = ad7091_convst,
 	.int_vref_mv = 2500,
 	.has_vref = true,
 	.reset = ad7091_reset,
-- 
2.50.1


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