2020-01-29 08:55:14

by Mircea Caprioru

Subject: [PATCH V3] iio: adc: ad7124: Add direct reg access

This patch adds the possibility to read and write registers from userspace
using the kernel debug direct register access option.

Signed-off-by: Mircea Caprioru <[email protected]>
---
Changelog v2 -> v3

- fix typo in commit message
- add bounds check for ad7124_reg_size

drivers/iio/adc/ad7124.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)

diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
index 52f45b13da4a..26e2677c97c5 100644
--- a/drivers/iio/adc/ad7124.c
+++ b/drivers/iio/adc/ad7124.c
@@ -71,6 +71,8 @@
#define AD7124_FILTER_FS_MSK GENMASK(10, 0)
#define AD7124_FILTER_FS(x) FIELD_PREP(AD7124_FILTER_FS_MSK, x)

+#define AD7124_REG_NO 57
+
enum ad7124_ids {
ID_AD7124_4,
ID_AD7124_8,
@@ -93,6 +95,14 @@ static const unsigned int ad7124_gain[8] = {
1, 2, 4, 8, 16, 32, 64, 128
};

+static const unsigned int ad7124_reg_size[] = {
+ 1, 2, 3, 3, 2, 1, 3, 3, 1, 2, 2, 2, 2,
+ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+ 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3,
+ 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+ 3, 3, 3, 3, 3
+};
+
static const int ad7124_master_clk_freq_hz[3] = {
[AD7124_LOW_POWER] = 76800,
[AD7124_MID_POWER] = 153600,
@@ -360,6 +370,27 @@ static int ad7124_write_raw(struct iio_dev *indio_dev,
}
}

+static int ad7124_reg_access(struct iio_dev *indio_dev,
+ unsigned int reg,
+ unsigned int writeval,
+ unsigned int *readval)
+{
+ struct ad7124_state *st = iio_priv(indio_dev);
+ int ret;
+
+ if (reg >= AD7124_REG_NO)
+ return -EINVAL;
+
+ if (readval)
+ ret = ad_sd_read_reg(&st->sd, reg, ad7124_reg_size[reg],
+ readval);
+ else
+ ret = ad_sd_write_reg(&st->sd, reg, ad7124_reg_size[reg],
+ writeval);
+
+ return ret;
+}
+
static IIO_CONST_ATTR(in_voltage_scale_available,
"0.000001164 0.000002328 0.000004656 0.000009313 0.000018626 0.000037252 0.000074505 0.000149011 0.000298023");

@@ -375,6 +406,7 @@ static const struct attribute_group ad7124_attrs_group = {
static const struct iio_info ad7124_info = {
.read_raw = ad7124_read_raw,
.write_raw = ad7124_write_raw,
+ .debugfs_reg_access = &ad7124_reg_access,
.validate_trigger = ad_sd_validate_trigger,
.attrs = &ad7124_attrs_group,
};
--
2.17.1

2020-01-29 18:50:28

by Lars-Peter Clausen

Subject: Re: [PATCH V3] iio: adc: ad7124: Add direct reg access

[...]
>
> +static int ad7124_reg_access(struct iio_dev *indio_dev,
> + unsigned int reg,
> + unsigned int writeval,
> + unsigned int *readval)
> +{
> + struct ad7124_state *st = iio_priv(indio_dev);
> + int ret;
> +
> + if (reg >= AD7124_REG_NO)

How about ARRAY_SIZE(ad7124_reg_size)? That will make sure that the
check is always correct and does not depend on an extra constant that
might go out-of-sync with the array. It also makes it easier for
reviewers to check that the code is correct. Otherwise they'll have to
count how many entries there are in ad7124_reg_size.

> + return -EINVAL;
> +
> + if (readval)
> + ret = ad_sd_read_reg(&st->sd, reg, ad7124_reg_size[reg],
> + readval);
> + else
> + ret = ad_sd_write_reg(&st->sd, reg, ad7124_reg_size[reg],
> + writeval);
> +
> + return ret;
> +}
> +
> static IIO_CONST_ATTR(in_voltage_scale_available,
> "0.000001164 0.000002328 0.000004656 0.000009313 0.000018626 0.000037252 0.000074505 0.000149011 0.000298023");
>
> @@ -375,6 +406,7 @@ static const struct attribute_group ad7124_attrs_group = {
> static const struct iio_info ad7124_info = {
> .read_raw = ad7124_read_raw,
> .write_raw = ad7124_write_raw,
> + .debugfs_reg_access = &ad7124_reg_access,
> .validate_trigger = ad_sd_validate_trigger,
> .attrs = &ad7124_attrs_group,
> };
>