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| author | Marek Vasut <marex@denx.de> | 2022-03-28 22:47:22 +0300 |
|---|---|---|
| committer | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2022-04-04 11:11:26 +0300 |
| commit | 3139ff24e2bc25d619ef822491651ecfb886db90 (patch) | |
| tree | 257d92f27870174fd958a4c180ca46d9e9b1581c /drivers/iio/adc/ti-ads1015.c | |
| parent | f1c9ce0ced2d2596bd979933ca9f57fdf8aabdfc (diff) | |
| download | linux-3139ff24e2bc25d619ef822491651ecfb886db90.tar.xz | |
iio: adc: ti-ads1015: Add static assert to test if shifted realbits fit into storagebits
Add compile-time static_assert wrapper to verify that shifted realbits
fit into storagebits. The macro is implemented in a more generic way so
it can be used to verify other values if required.
Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Cc: Daniel Baluta <daniel.baluta@nxp.com>
Link: https://lore.kernel.org/r/20220328194725.149150-7-marex@denx.de
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Diffstat (limited to 'drivers/iio/adc/ti-ads1015.c')
| -rw-r--r-- | drivers/iio/adc/ti-ads1015.c | 26 |
1 files changed, 24 insertions, 2 deletions
diff --git a/drivers/iio/adc/ti-ads1015.c b/drivers/iio/adc/ti-ads1015.c index 51ab8bb3d9f1..73d848804a12 100644 --- a/drivers/iio/adc/ti-ads1015.c +++ b/drivers/iio/adc/ti-ads1015.c @@ -135,6 +135,28 @@ static const struct iio_event_spec ads1015_events[] = { }, }; +/* + * Compile-time check whether _fitbits can accommodate up to _testbits + * bits. Returns _fitbits on success, fails to compile otherwise. + * + * The test works such that it multiplies constant _fitbits by constant + * double-negation of size of a non-empty structure, i.e. it multiplies + * constant _fitbits by constant 1 in each successful compilation case. + * The non-empty structure may contain C11 _Static_assert(), make use of + * this and place the kernel variant of static assert in there, so that + * it performs the compile-time check for _testbits <= _fitbits. Note + * that it is not possible to directly use static_assert in compound + * statements, hence this convoluted construct. + */ +#define FIT_CHECK(_testbits, _fitbits) \ + ( \ + (_fitbits) * \ + !!sizeof(struct { \ + static_assert((_testbits) <= (_fitbits)); \ + int pad; \ + }) \ + ) + #define ADS1015_V_CHAN(_chan, _addr, _realbits, _shift, _event_spec, _num_event_specs) { \ .type = IIO_VOLTAGE, \ .indexed = 1, \ @@ -147,7 +169,7 @@ static const struct iio_event_spec ads1015_events[] = { .scan_type = { \ .sign = 's', \ .realbits = (_realbits), \ - .storagebits = 16, \ + .storagebits = FIT_CHECK((_realbits) + (_shift), 16), \ .shift = (_shift), \ .endianness = IIO_CPU, \ }, \ @@ -170,7 +192,7 @@ static const struct iio_event_spec ads1015_events[] = { .scan_type = { \ .sign = 's', \ .realbits = (_realbits), \ - .storagebits = 16, \ + .storagebits = FIT_CHECK((_realbits) + (_shift), 16), \ .shift = (_shift), \ .endianness = IIO_CPU, \ }, \ |