iio: addac: ad74xxx: Constify struct iio_chan_spec​

'struct iio_chan_spec' are not modified in these drivers.

Constifying this structure moves some data to a read-only section, so
increase overall security.

On a x86_64, with allmodconfig:
Before:
======
   text	   data	    bss	    dec	    hex	filename
  35749	   5879	    384	  42012	   a41c	drivers/iio/addac/ad74115.o
  32242	   3297	    384	  35923	   8c53	drivers/iio/addac/ad74413r.o

After:
=====
   text	   data	    bss	    dec	    hex	filename
  39109	   2519	    384	  42012	   a41c	drivers/iio/addac/ad74115.o
  33842	   1697	    384	  35923	   8c53	drivers/iio/addac/ad74413r.o

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://patch.msgid.link/da291278e78b983ea2e657a25769f7d82ea2a6d0.1725717045.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

2 files changed, 20 insertions, 19 deletions

diff --git a/drivers/iio/addac/ad74115.c b/drivers/iio/addac/ad74115.c
index 12dc43d487b4..bdbdd67536ff 100644
--- a/drivers/iio/addac/ad74115.c
+++ b/drivers/iio/addac/ad74115.c
@@ -191,7 +191,7 @@ enum ad74115_gpio_mode {
 };
 
 struct ad74115_channels {
-	struct iio_chan_spec		*channels;
+	const struct iio_chan_spec	*channels;
 	unsigned int			num_channels;
 };
 
@@ -1295,46 +1295,46 @@ static const struct iio_info ad74115_info = {
 	_AD74115_ADC_CHANNEL(_type, index, BIT(IIO_CHAN_INFO_SCALE)	\
 					   | BIT(IIO_CHAN_INFO_OFFSET))
 
-static struct iio_chan_spec ad74115_voltage_input_channels[] = {
+static const struct iio_chan_spec ad74115_voltage_input_channels[] = {
 	AD74115_ADC_CHANNEL(IIO_VOLTAGE, AD74115_ADC_CH_CONV1),
 	AD74115_ADC_CHANNEL(IIO_VOLTAGE, AD74115_ADC_CH_CONV2),
 };
 
-static struct iio_chan_spec ad74115_voltage_output_channels[] = {
+static const struct iio_chan_spec ad74115_voltage_output_channels[] = {
 	AD74115_DAC_CHANNEL(IIO_VOLTAGE, AD74115_DAC_CH_MAIN),
 	AD74115_ADC_CHANNEL(IIO_CURRENT, AD74115_ADC_CH_CONV1),
 	AD74115_ADC_CHANNEL(IIO_VOLTAGE, AD74115_ADC_CH_CONV2),
 };
 
-static struct iio_chan_spec ad74115_current_input_channels[] = {
+static const struct iio_chan_spec ad74115_current_input_channels[] = {
 	AD74115_ADC_CHANNEL(IIO_CURRENT, AD74115_ADC_CH_CONV1),
 	AD74115_ADC_CHANNEL(IIO_VOLTAGE, AD74115_ADC_CH_CONV2),
 };
 
-static struct iio_chan_spec ad74115_current_output_channels[] = {
+static const struct iio_chan_spec ad74115_current_output_channels[] = {
 	AD74115_DAC_CHANNEL(IIO_CURRENT, AD74115_DAC_CH_MAIN),
 	AD74115_ADC_CHANNEL(IIO_VOLTAGE, AD74115_ADC_CH_CONV1),
 	AD74115_ADC_CHANNEL(IIO_VOLTAGE, AD74115_ADC_CH_CONV2),
 };
 
-static struct iio_chan_spec ad74115_2_wire_resistance_input_channels[] = {
+static const struct iio_chan_spec ad74115_2_wire_resistance_input_channels[] = {
 	_AD74115_ADC_CHANNEL(IIO_RESISTANCE, AD74115_ADC_CH_CONV1,
 			     BIT(IIO_CHAN_INFO_PROCESSED)),
 	AD74115_ADC_CHANNEL(IIO_VOLTAGE, AD74115_ADC_CH_CONV2),
 };
 
-static struct iio_chan_spec ad74115_3_4_wire_resistance_input_channels[] = {
+static const struct iio_chan_spec ad74115_3_4_wire_resistance_input_channels[] = {
 	AD74115_ADC_CHANNEL(IIO_RESISTANCE, AD74115_ADC_CH_CONV1),
 	AD74115_ADC_CHANNEL(IIO_VOLTAGE, AD74115_ADC_CH_CONV2),
 };
 
-static struct iio_chan_spec ad74115_digital_input_logic_channels[] = {
+static const struct iio_chan_spec ad74115_digital_input_logic_channels[] = {
 	AD74115_DAC_CHANNEL(IIO_VOLTAGE, AD74115_DAC_CH_COMPARATOR),
 	AD74115_ADC_CHANNEL(IIO_VOLTAGE, AD74115_ADC_CH_CONV1),
 	AD74115_ADC_CHANNEL(IIO_VOLTAGE, AD74115_ADC_CH_CONV2),
 };
 
-static struct iio_chan_spec ad74115_digital_input_loop_channels[] = {
+static const struct iio_chan_spec ad74115_digital_input_loop_channels[] = {
 	AD74115_DAC_CHANNEL(IIO_CURRENT, AD74115_DAC_CH_MAIN),
 	AD74115_DAC_CHANNEL(IIO_VOLTAGE, AD74115_DAC_CH_COMPARATOR),
 	AD74115_ADC_CHANNEL(IIO_VOLTAGE, AD74115_ADC_CH_CONV1),
diff --git a/drivers/iio/addac/ad74413r.c b/drivers/iio/addac/ad74413r.c
index 2410d72da49b..1e2f6d9804e3 100644
--- a/drivers/iio/addac/ad74413r.c
+++ b/drivers/iio/addac/ad74413r.c
@@ -45,8 +45,8 @@ struct ad74413r_channel_config {
 };
 
 struct ad74413r_channels {
-	struct iio_chan_spec	*channels;
-	unsigned int		num_channels;
+	const struct iio_chan_spec	*channels;
+	unsigned int			num_channels;
 };
 
 struct ad74413r_state {
@@ -1138,34 +1138,34 @@ static const struct iio_info ad74413r_info = {
 	AD74413R_ADC_CHANNEL(IIO_CURRENT,  BIT(IIO_CHAN_INFO_SCALE)	\
 			     | BIT(IIO_CHAN_INFO_OFFSET))
 
-static struct iio_chan_spec ad74413r_voltage_output_channels[] = {
+static const struct iio_chan_spec ad74413r_voltage_output_channels[] = {
 	AD74413R_DAC_CHANNEL(IIO_VOLTAGE, BIT(IIO_CHAN_INFO_SCALE)),
 	AD74413R_ADC_CURRENT_CHANNEL,
 };
 
-static struct iio_chan_spec ad74413r_current_output_channels[] = {
+static const struct iio_chan_spec ad74413r_current_output_channels[] = {
 	AD74413R_DAC_CHANNEL(IIO_CURRENT, BIT(IIO_CHAN_INFO_SCALE)),
 	AD74413R_ADC_VOLTAGE_CHANNEL,
 };
 
-static struct iio_chan_spec ad74413r_voltage_input_channels[] = {
+static const struct iio_chan_spec ad74413r_voltage_input_channels[] = {
 	AD74413R_ADC_VOLTAGE_CHANNEL,
 };
 
-static struct iio_chan_spec ad74413r_current_input_channels[] = {
+static const struct iio_chan_spec ad74413r_current_input_channels[] = {
 	AD74413R_ADC_CURRENT_CHANNEL,
 };
 
-static struct iio_chan_spec ad74413r_current_input_loop_channels[] = {
+static const struct iio_chan_spec ad74413r_current_input_loop_channels[] = {
 	AD74413R_DAC_CHANNEL(IIO_CURRENT, BIT(IIO_CHAN_INFO_SCALE)),
 	AD74413R_ADC_CURRENT_CHANNEL,
 };
 
-static struct iio_chan_spec ad74413r_resistance_input_channels[] = {
+static const struct iio_chan_spec ad74413r_resistance_input_channels[] = {
 	AD74413R_ADC_CHANNEL(IIO_RESISTANCE, BIT(IIO_CHAN_INFO_PROCESSED)),
 };
 
-static struct iio_chan_spec ad74413r_digital_input_channels[] = {
+static const struct iio_chan_spec ad74413r_digital_input_channels[] = {
 	AD74413R_ADC_VOLTAGE_CHANNEL,
 };
 
@@ -1270,7 +1270,8 @@ static int ad74413r_setup_channels(struct iio_dev *indio_dev)
 {
 	struct ad74413r_state *st = iio_priv(indio_dev);
 	struct ad74413r_channel_config *config;
-	struct iio_chan_spec *channels, *chans;
+	const struct iio_chan_spec *chans;
+	struct iio_chan_spec *channels;
 	unsigned int i, num_chans, chan_i;
 	int ret;