Re: [PATCH v3 1/1] staging: iio: adc: ad7280a: use crc8.h API to build crc table

[Jonathan Cameron <jic23@kernel.org>]

On Fri, 19 Oct 2018 08:41:00 +0200
Lars-Peter Clausen <lars@metafoo.de> wrote:

> On 10/18/2018 08:59 PM, Slawomir Stepien wrote:
> > The custom build function ad7280_crc8_build_table is not needed. The
> > crc8_populate_msb function from linux/crc8.h will build the same crc
> > table.
> > 
> > Signed-off-by: Slawomir Stepien <sst@poczta.fm>  
> 
> Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Applied to the togreg branch of iio.git and pushed out as testing for
the autobuilders to play with it.

Thanks,

Jonathan

> 
> > ---
> > Since v2:
> > * Fix compilation by adding "select CRC8" in Kconfig.
> > 
> > Since v1:
> > * Fix typo in commit message.
> > ---
> >  drivers/staging/iio/adc/Kconfig   |  1 +
> >  drivers/staging/iio/adc/ad7280a.c | 24 +++---------------------
> >  2 files changed, 4 insertions(+), 21 deletions(-)
> > 
> > diff --git a/drivers/staging/iio/adc/Kconfig b/drivers/staging/iio/adc/Kconfig
> > index e17efb03bac0..d6bd1bb9d2e6 100644
> > --- a/drivers/staging/iio/adc/Kconfig
> > +++ b/drivers/staging/iio/adc/Kconfig
> > @@ -73,6 +73,7 @@ config AD7192
> >  config AD7280
> >  	tristate "Analog Devices AD7280A Lithium Ion Battery Monitoring System"
> >  	depends on SPI
> > +	select CRC8
> >  	help
> >  	  Say yes here to build support for Analog Devices AD7280A
> >  	  Lithium Ion Battery Monitoring System.
> > diff --git a/drivers/staging/iio/adc/ad7280a.c b/drivers/staging/iio/adc/ad7280a.c
> > index b736275c10f5..c701f07853fa 100644
> > --- a/drivers/staging/iio/adc/ad7280a.c
> > +++ b/drivers/staging/iio/adc/ad7280a.c
> > @@ -6,6 +6,7 @@
> >   * Licensed under the GPL-2.
> >   */
> >  
> > +#include <linux/crc8.h>
> >  #include <linux/device.h>
> >  #include <linux/kernel.h>
> >  #include <linux/slab.h>
> > @@ -121,8 +122,6 @@ static unsigned int ad7280a_devaddr(unsigned int addr)
> >   * P(x) = x^8 + x^5 + x^3 + x^2 + x^1 + x^0 = 0b100101111 => 0x2F
> >   */
> >  #define POLYNOM		0x2F
> > -#define POLYNOM_ORDER	8
> > -#define HIGHBIT		(1 << (POLYNOM_ORDER - 1))
> >  
> >  struct ad7280_state {
> >  	struct spi_device		*spi;
> > @@ -131,7 +130,7 @@ struct ad7280_state {
> >  	int				slave_num;
> >  	int				scan_cnt;
> >  	int				readback_delay_us;
> > -	unsigned char			crc_tab[256];
> > +	unsigned char			crc_tab[CRC8_TABLE_SIZE];
> >  	unsigned char			ctrl_hb;
> >  	unsigned char			ctrl_lb;
> >  	unsigned char			cell_threshhigh;
> > @@ -144,23 +143,6 @@ struct ad7280_state {
> >  	__be32				buf[2] ____cacheline_aligned;
> >  };
> >  
> > -static void ad7280_crc8_build_table(unsigned char *crc_tab)
> > -{
> > -	unsigned char bit, crc;
> > -	int cnt, i;
> > -
> > -	for (cnt = 0; cnt < 256; cnt++) {
> > -		crc = cnt;
> > -		for (i = 0; i < 8; i++) {
> > -			bit = crc & HIGHBIT;
> > -			crc <<= 1;
> > -			if (bit)
> > -				crc ^= POLYNOM;
> > -		}
> > -		crc_tab[cnt] = crc;
> > -	}
> > -}
> > -
> >  static unsigned char ad7280_calc_crc8(unsigned char *crc_tab, unsigned int val)
> >  {
> >  	unsigned char crc;
> > @@ -857,7 +839,7 @@ static int ad7280_probe(struct spi_device *spi)
> >  	if (!pdata)
> >  		pdata = &ad7793_default_pdata;
> >  
> > -	ad7280_crc8_build_table(st->crc_tab);
> > +	crc8_populate_msb(st->crc_tab, POLYNOM);
> >  
> >  	st->spi->max_speed_hz = AD7280A_MAX_SPI_CLK_HZ;
> >  	st->spi->mode = SPI_MODE_1;
> >   
>