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Commit 4ea71e5c authored by Akinobu Mita's avatar Akinobu Mita Committed by Jonathan Cameron
Browse files

iio: adc: mcp320x: support more differential voltage measurement 



mcp320x driver supports the pseudo-differential mode by
in_voltage'IN+'-voltage'IN-'_raw where (IN+, IN-) = (0, 1), (2, 3), ...

mcp320x chips except MCP3X01 can also select swapped IN+ and IN-
pairs in the pseudo-differential mode.
i.e. in_voltage'IN+'-voltage'IN-'_raw where (IN+, IN-) = (1, 0),
(3, 2), ...

If the voltage level of IN+ is equal to or less than IN-, the
resultant code will be 000h.  So it is useful to provide these, too.

Signed-off-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Cc: Oskar Andero <oskar.andero@gmail.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Hartmut Knaack <knaack.h@gmx.de>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Peter Meerwald <pmeerw@pmeerw.net>
Cc: linux-iio@vger.kernel.org
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent b9cd7a25

drivers/iio/adc/mcp320x.c

+19 −12
Original line number Diff line number Diff line
@@ -187,26 +187,27 @@ static int mcp320x_read_raw(struct iio_dev *indio_dev, 
		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \

	}



#define MCP320X_VOLTAGE_CHANNEL_DIFF(num)			\

#define MCP320X_VOLTAGE_CHANNEL_DIFF(chan1, chan2)		\

	{							\

		.type = IIO_VOLTAGE,				\

		.indexed = 1,					\

		.channel = (num * 2),				\

		.channel2 = (num * 2 + 1),			\

		.address = (num * 2),				\

		.channel = (chan1),				\

		.channel2 = (chan2),				\

		.address = (chan1),				\

		.differential = 1,				\

		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\

		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \

	}



static const struct iio_chan_spec mcp3201_channels[] = {

	MCP320X_VOLTAGE_CHANNEL_DIFF(0),

	MCP320X_VOLTAGE_CHANNEL_DIFF(0, 1),

};



static const struct iio_chan_spec mcp3202_channels[] = {

	MCP320X_VOLTAGE_CHANNEL(0),

	MCP320X_VOLTAGE_CHANNEL(1),

	MCP320X_VOLTAGE_CHANNEL_DIFF(0),

	MCP320X_VOLTAGE_CHANNEL_DIFF(0, 1),

	MCP320X_VOLTAGE_CHANNEL_DIFF(1, 0),

};



static const struct iio_chan_spec mcp3204_channels[] = {
@@ -214,8 +215,10 @@ static const struct iio_chan_spec mcp3204_channels[] = { 
	MCP320X_VOLTAGE_CHANNEL(1),

	MCP320X_VOLTAGE_CHANNEL(2),

	MCP320X_VOLTAGE_CHANNEL(3),

	MCP320X_VOLTAGE_CHANNEL_DIFF(0),

	MCP320X_VOLTAGE_CHANNEL_DIFF(1),

	MCP320X_VOLTAGE_CHANNEL_DIFF(0, 1),

	MCP320X_VOLTAGE_CHANNEL_DIFF(1, 0),

	MCP320X_VOLTAGE_CHANNEL_DIFF(2, 3),

	MCP320X_VOLTAGE_CHANNEL_DIFF(3, 2),

};



static const struct iio_chan_spec mcp3208_channels[] = {
@@ -227,10 +230,14 @@ static const struct iio_chan_spec mcp3208_channels[] = { 
	MCP320X_VOLTAGE_CHANNEL(5),

	MCP320X_VOLTAGE_CHANNEL(6),

	MCP320X_VOLTAGE_CHANNEL(7),

	MCP320X_VOLTAGE_CHANNEL_DIFF(0),

	MCP320X_VOLTAGE_CHANNEL_DIFF(1),

	MCP320X_VOLTAGE_CHANNEL_DIFF(2),

	MCP320X_VOLTAGE_CHANNEL_DIFF(3),

	MCP320X_VOLTAGE_CHANNEL_DIFF(0, 1),

	MCP320X_VOLTAGE_CHANNEL_DIFF(1, 0),

	MCP320X_VOLTAGE_CHANNEL_DIFF(2, 3),

	MCP320X_VOLTAGE_CHANNEL_DIFF(3, 2),

	MCP320X_VOLTAGE_CHANNEL_DIFF(4, 5),

	MCP320X_VOLTAGE_CHANNEL_DIFF(5, 4),

	MCP320X_VOLTAGE_CHANNEL_DIFF(6, 7),

	MCP320X_VOLTAGE_CHANNEL_DIFF(7, 6),

};



static const struct iio_info mcp320x_info = {