Hi Prafulla,
I haven't received feedback about this patch from you. Can I please kindly
remind you about it since I am about to send patches that deal with SPI clk
setting.
Thank you.
On 06/29/2012 02:17 PM, Valentin Longchamp wrote:
> The computation was not correct with low clock values: setting a 1MHz
> clock would result in an overlap that would then configure a 25Mhz
> clock.
>
> This patch implements a correct computation method according to the
> kirkwood functionnal spec. table 629 (Serial Memory Interface
> Configuration Register).
>
> Signed-off-by: Valentin Longchamp <valentin.longch...@keymile.com>
> cc: Holger Brunck <holger.bru...@keymile.com>
> cc: Prafulla Wadaskar <prafu...@marvell.com>
> ---
> arch/arm/include/asm/arch-kirkwood/spi.h | 1 +
> drivers/spi/kirkwood_spi.c | 5 +++--
> 2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/include/asm/arch-kirkwood/spi.h
> b/arch/arm/include/asm/arch-kirkwood/spi.h
> index 1d5043f..5a38dc5 100644
> --- a/arch/arm/include/asm/arch-kirkwood/spi.h
> +++ b/arch/arm/include/asm/arch-kirkwood/spi.h
> @@ -38,6 +38,7 @@ struct kwspi_registers {
> };
>
> #define KWSPI_CLKPRESCL_MASK 0x1f
> +#define KWSPI_CLKPRESCL_MIN 0x12
> #define KWSPI_CSN_ACT 1 /* Activates serial memory interface
> */
> #define KWSPI_SMEMRDY (1 << 1) /* SerMem Data xfer ready */
> #define KWSPI_IRQUNMASK 1 /* unmask SPI interrupt */
> diff --git a/drivers/spi/kirkwood_spi.c b/drivers/spi/kirkwood_spi.c
> index ee14669..9b3f6a4 100644
> --- a/drivers/spi/kirkwood_spi.c
> +++ b/drivers/spi/kirkwood_spi.c
> @@ -57,8 +57,9 @@ struct spi_slave *spi_setup_slave(unsigned int bus,
> unsigned int cs,
> writel(~KWSPI_CSN_ACT | KWSPI_SMEMRDY, &spireg->ctrl);
>
> /* calculate spi clock prescaller using max_hz */
> - data = ((CONFIG_SYS_TCLK / 2) / max_hz) & KWSPI_CLKPRESCL_MASK;
> - data |= 0x10;
> + data = ((CONFIG_SYS_TCLK / 2) / max_hz) + 0x10;
> + data = data < KWSPI_CLKPRESCL_MIN ? KWSPI_CLKPRESCL_MIN : data;
> + data = data > KWSPI_CLKPRESCL_MASK ? KWSPI_CLKPRESCL_MASK : data;
>
> /* program spi clock prescaller using max_hz */
> writel(KWSPI_ADRLEN_3BYTE | data, &spireg->cfg);
>
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