iio:ad5064: Structural changes to support LTC2617

This patch makes minor structural changes to support specifics
for LTC2617 DAC. This DAC requires different handling of the
power down modes. The configuration to actually support the
DAC will be submitted in a secondary patch.

Adjust the DECLARE_AD5064_CHANNELS() macro to accept a new
ext_info parameter. This allows to use different power down
modes per DAC. (e.g. DAC only support 90kohm to ground)

Add the chip_info parameter "powerdown_ltc". This parameter is
used in the ad5064_sync_powerdown_mode() function to handle the
power down command for LTC diffently. For those devices the
power down command must be addressed to the channel.
Signed-off-by: Marc Andre <marc.andre@netline.ch>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/dac/ad5064.c

@@ -50,10 +50,12 @@
 /**
  * struct ad5064_chip_info - chip specific information
  * @shared_vref:	whether the vref supply is shared between channels
- * @internal_vref:	internal reference voltage. 0 if the chip has no internal
- *			vref.
+ * @internal_vref:	internal reference voltage. 0 if the chip has no
+			internal vref.
  * @channel:		channel specification
  * @num_channels:	number of channels
+ * @powerdown_ltc:	Use alternative power down addressing as required by
+ *			ltc2617 and others.
  */
 
 struct ad5064_chip_info {
@@ -61,6 +63,7 @@ struct ad5064_chip_info {
 	unsigned long internal_vref;
 	const struct iio_chan_spec *channels;
 	unsigned int num_channels;
+	bool powerdown_ltc;
 };
 
 struct ad5064_state;
@@ -136,15 +139,21 @@ static int ad5064_write(struct ad5064_state *st, unsigned int cmd,
 static int ad5064_sync_powerdown_mode(struct ad5064_state *st,
 	const struct iio_chan_spec *chan)
 {
-	unsigned int val;
+	unsigned int val, address;
 	int ret;
 
+	if (st->chip_info->powerdown_ltc) {
+		val = 0;
+		address = chan->address;
+	} else {
+		address = 0;
 		val = (0x1 << chan->address);
 
 		if (st->pwr_down[chan->channel])
 			val |= st->pwr_down_mode[chan->channel] << 8;
+	}
 
-	ret = ad5064_write(st, AD5064_CMD_POWERDOWN_DAC, 0, val, 0);
+	ret = ad5064_write(st, AD5064_CMD_POWERDOWN_DAC, address, val, 0);
 
 	return ret;
 }
@@ -295,7 +304,7 @@ static const struct iio_chan_spec_ext_info ad5064_ext_info[] = {
 	{ },
 };
 
-#define AD5064_CHANNEL(chan, addr, bits, _shift) {		\
+#define AD5064_CHANNEL(chan, addr, bits, _shift, _ext_info) {		\
 	.type = IIO_VOLTAGE,					\
 	.indexed = 1,						\
 	.output = 1,						\
@@ -309,37 +318,37 @@ static const struct iio_chan_spec_ext_info ad5064_ext_info[] = {
 		.storagebits = 16,				\
 		.shift = (_shift),				\
 	},							\
-	.ext_info = ad5064_ext_info,				\
+	.ext_info = (_ext_info),				\
 }
 
-#define DECLARE_AD5064_CHANNELS(name, bits, shift) \
+#define DECLARE_AD5064_CHANNELS(name, bits, shift, ext_info) \
 const struct iio_chan_spec name[] = { \
-	AD5064_CHANNEL(0, 0, bits, shift), \
-	AD5064_CHANNEL(1, 1, bits, shift), \
-	AD5064_CHANNEL(2, 2, bits, shift), \
-	AD5064_CHANNEL(3, 3, bits, shift), \
-	AD5064_CHANNEL(4, 4, bits, shift), \
-	AD5064_CHANNEL(5, 5, bits, shift), \
-	AD5064_CHANNEL(6, 6, bits, shift), \
-	AD5064_CHANNEL(7, 7, bits, shift), \
+	AD5064_CHANNEL(0, 0, bits, shift, ext_info), \
+	AD5064_CHANNEL(1, 1, bits, shift, ext_info), \
+	AD5064_CHANNEL(2, 2, bits, shift, ext_info), \
+	AD5064_CHANNEL(3, 3, bits, shift, ext_info), \
+	AD5064_CHANNEL(4, 4, bits, shift, ext_info), \
+	AD5064_CHANNEL(5, 5, bits, shift, ext_info), \
+	AD5064_CHANNEL(6, 6, bits, shift, ext_info), \
+	AD5064_CHANNEL(7, 7, bits, shift, ext_info), \
 }
 
-#define DECLARE_AD5065_CHANNELS(name, bits, shift) \
+#define DECLARE_AD5065_CHANNELS(name, bits, shift, ext_info) \
 const struct iio_chan_spec name[] = { \
-	AD5064_CHANNEL(0, 0, bits, shift), \
-	AD5064_CHANNEL(1, 3, bits, shift), \
+	AD5064_CHANNEL(0, 0, bits, shift, ext_info), \
+	AD5064_CHANNEL(1, 3, bits, shift, ext_info), \
 }
 
-static DECLARE_AD5064_CHANNELS(ad5024_channels, 12, 8);
-static DECLARE_AD5064_CHANNELS(ad5044_channels, 14, 6);
-static DECLARE_AD5064_CHANNELS(ad5064_channels, 16, 4);
+static DECLARE_AD5064_CHANNELS(ad5024_channels, 12, 8, ad5064_ext_info);
+static DECLARE_AD5064_CHANNELS(ad5044_channels, 14, 6, ad5064_ext_info);
+static DECLARE_AD5064_CHANNELS(ad5064_channels, 16, 4, ad5064_ext_info);
 
-static DECLARE_AD5065_CHANNELS(ad5025_channels, 12, 8);
-static DECLARE_AD5065_CHANNELS(ad5045_channels, 14, 6);
-static DECLARE_AD5065_CHANNELS(ad5065_channels, 16, 4);
+static DECLARE_AD5065_CHANNELS(ad5025_channels, 12, 8, ad5064_ext_info);
+static DECLARE_AD5065_CHANNELS(ad5045_channels, 14, 6, ad5064_ext_info);
+static DECLARE_AD5065_CHANNELS(ad5065_channels, 16, 4, ad5064_ext_info);
 
-static DECLARE_AD5064_CHANNELS(ad5629_channels, 12, 4);
-static DECLARE_AD5064_CHANNELS(ad5669_channels, 16, 0);
+static DECLARE_AD5064_CHANNELS(ad5629_channels, 12, 4, ad5064_ext_info);
+static DECLARE_AD5064_CHANNELS(ad5669_channels, 16, 0, ad5064_ext_info);
 
 static const struct ad5064_chip_info ad5064_chip_info_tbl[] = {
 	[ID_AD5024] = {