Hi Aaron, Thanks for the fixes! Some comments below:
On 2015-03-30 19:49, Aaron Brice wrote: > Add delay between chip select and clock signals, before clock starts and > after clock stops. This 50ns are specifc to the SPI slave at hand (SRAM) is this correct? If yes, this would probably need new slave properties. I found a TI controller which also supports such properties: http://lists.infradead.org/pipermail/linux-arm-kernel/2014-September/285761.html > > Signed-off-by: Aaron Brice <aaron.br...@datasoft.com> > --- > drivers/spi/spi-fsl-dspi.c | 53 > ++++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 51 insertions(+), 2 deletions(-) > > diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c > index 96cac87..41284cc 100644 > --- a/drivers/spi/spi-fsl-dspi.c > +++ b/drivers/spi/spi-fsl-dspi.c > @@ -20,6 +20,7 @@ > #include <linux/interrupt.h> > #include <linux/io.h> > #include <linux/kernel.h> > +#include <linux/math64.h> > #include <linux/module.h> > #include <linux/of.h> > #include <linux/of_device.h> > @@ -51,7 +52,7 @@ > #define SPI_CTAR_CPOL(x) ((x) << 26) > #define SPI_CTAR_CPHA(x) ((x) << 25) > #define SPI_CTAR_LSBFE(x) ((x) << 24) > -#define SPI_CTAR_PCSSCR(x) (((x) & 0x00000003) << 22) > +#define SPI_CTAR_PCSSCK(x) (((x) & 0x00000003) << 22) > #define SPI_CTAR_PASC(x) (((x) & 0x00000003) << 20) > #define SPI_CTAR_PDT(x) (((x) & 0x00000003) << 18) > #define SPI_CTAR_PBR(x) (((x) & 0x00000003) << 16) > @@ -59,6 +60,7 @@ > #define SPI_CTAR_ASC(x) (((x) & 0x0000000f) << 8) > #define SPI_CTAR_DT(x) (((x) & 0x0000000f) << 4) > #define SPI_CTAR_BR(x) ((x) & 0x0000000f) > +#define SPI_CTAR_SCALE_BITS 0xf > > #define SPI_CTAR0_SLAVE 0x0c > > @@ -99,6 +101,8 @@ > #define SPI_CS_ASSERT 0x02 > #define SPI_CS_DROP 0x04 > > +#define NSEC_PER_SEC 1000000000L > + Avoid redefine this, should be available from headers (e.g. time.h) > struct chip_data { > u32 mcr_val; > u32 ctar_val; > @@ -174,6 +178,40 @@ static void hz_to_spi_baud(char *pbr, char *br, > int speed_hz, > } > } > > +static void ns_delay_scale(char *psc, char *sc, int delay_ns, > + unsigned long clkrate) > +{ > + int pscale_tbl[4] = {1, 3, 5, 7}; > + int scale_needed, scale, minscale = INT_MAX; > + int i, j; > + u32 remainder; > + > + scale_needed = div_u64_rem((u64)delay_ns * clkrate, NSEC_PER_SEC, > + &remainder); > + if (remainder) > + scale_needed++; > + > + for (i = 0; i < ARRAY_SIZE(pscale_tbl); i++) > + for (j = 0; j <= SPI_CTAR_SCALE_BITS; j++) { > + scale = pscale_tbl[i] * (2 << j); > + if (scale >= scale_needed) { > + if (scale < minscale) { > + minscale = scale; > + *psc = i; > + *sc = j; > + } > + break; > + } > + } > + > + if (minscale == INT_MAX) { > + pr_warn("Cannot find correct scale values for %dns delay at > clkrate > %ld, using max prescaler value", > + delay_ns, clkrate); > + *psc = ARRAY_SIZE(pscale_tbl) - 1; > + *sc = SPI_CTAR_SCALE_BITS; > + } > +} > + > static int dspi_transfer_write(struct fsl_dspi *dspi) > { > int tx_count = 0; > @@ -352,7 +390,8 @@ static int dspi_setup(struct spi_device *spi) > { > struct chip_data *chip; > struct fsl_dspi *dspi = spi_master_get_devdata(spi->master); > - unsigned char br = 0, pbr = 0, fmsz = 0; > + unsigned char br = 0, pbr = 0, pcssck = 0, cssck = 0; > + unsigned char pasc = 0, asc = 0, fmsz = 0; > > if ((spi->bits_per_word >= 4) && (spi->bits_per_word <= 16)) { > fmsz = spi->bits_per_word - 1; > @@ -377,10 +416,20 @@ static int dspi_setup(struct spi_device *spi) > hz_to_spi_baud(&pbr, &br, > spi->max_speed_hz, clk_get_rate(dspi->clk)); > > + /* Set PCS to SCK delay scale values for 50ns delay*/ > + ns_delay_scale(&pcssck, &cssck, 50, clk_get_rate(dspi->clk)); > + > + /* Set After SCK delay scale values for 50ns delay*/ > + ns_delay_scale(&pasc, &asc, 50, clk_get_rate(dspi->clk)); > + This functions calls clk_get_rate three times, can you add a local variable for it? > chip->ctar_val = SPI_CTAR_FMSZ(fmsz) > | SPI_CTAR_CPOL(spi->mode & SPI_CPOL ? 1 : 0) > | SPI_CTAR_CPHA(spi->mode & SPI_CPHA ? 1 : 0) > | SPI_CTAR_LSBFE(spi->mode & SPI_LSB_FIRST ? 1 : 0) > + | SPI_CTAR_PCSSCK(pcssck) > + | SPI_CTAR_CSSCK(cssck) > + | SPI_CTAR_PASC(pasc) > + | SPI_CTAR_ASC(asc) > | SPI_CTAR_PBR(pbr) > | SPI_CTAR_BR(br); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
