[U-Boot] [PATCH v2 3/4] kw_spi: support spi_claim/release_bus functions

[Prafulla Wadaskar]

> -----Original Message-----
> From: Valentin Longchamp [mailto:valentin.longchamp at keymile.com]
> Sent: 30 May 2012 21:12
> To: Prafulla Wadaskar
> Cc: Valentin Longchamp; holger.brunck at keymile.com; u-
> boot at lists.denx.de; Prafulla Wadaskar
> Subject: [PATCH v2 3/4] kw_spi: support spi_claim/release_bus
> functions
> 
> These two function nows ensure that the MPP is configured correctly
> for
> the SPI controller before any SPI access, and restore the initial
> configuration when the access is over.
> 
> Since the used pins for the SPI controller can differ (2 possibilities
> for each signal), the used pins are configured with
> CONFIG_SYS_KW_SPI_MPP.
> 
> Signed-off-by: Valentin Longchamp <valentin.longchamp at keymile.com>
> cc: Holger Brunck <holger.brunck at keymile.com>
> cc: Prafulla Wadaskar <prafulla at marvell.com>
> ---
>  arch/arm/include/asm/arch-kirkwood/spi.h |   11 ++++++++
>  drivers/spi/kirkwood_spi.c               |   38
> ++++++++++++++++++++++++++++++
>  2 files changed, 49 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/arm/include/asm/arch-kirkwood/spi.h
> b/arch/arm/include/asm/arch-kirkwood/spi.h
> index 1d5043f..c79bed7 100644
> --- a/arch/arm/include/asm/arch-kirkwood/spi.h
> +++ b/arch/arm/include/asm/arch-kirkwood/spi.h
> @@ -37,6 +37,17 @@ struct kwspi_registers {
>  	u32 irq_mask;	/* 0x10614 */
>  };
> 
> +/* They are used to define CONFIG_SYS_KW_SPI_MPP
> + * each of the below #defines selects which mpp is
> + * configured for each SPI signal in spi_claim_bus
> + * bit 0: selects pin for MOSI (MPP1 if 0, MPP6 if 1)
> + * bit 1: selects pin for SCK (MPP2 if 0, MPP10 if 1)
> + * bit 2: selects pin for MISO (MPP3 if 0, MPP11 if 1)
> + */
> +#define MOSI_MPP6	(1 << 0)
> +#define SCK_MPP10	(1 << 1)
> +#define MISO_MPP11	(1 << 2)
> +
>  #define KWSPI_CLKPRESCL_MASK	0x1f
>  #define KWSPI_CSN_ACT		1 /* Activates serial memory interface
> */
>  #define KWSPI_SMEMRDY		(1 << 1) /* SerMem Data xfer ready */
> diff --git a/drivers/spi/kirkwood_spi.c b/drivers/spi/kirkwood_spi.c
> index 2fd89d2..a3e6b6e 100644
> --- a/drivers/spi/kirkwood_spi.c
> +++ b/drivers/spi/kirkwood_spi.c
> @@ -84,13 +84,51 @@ void spi_free_slave(struct spi_slave *slave)
>  	free(slave);
>  }
> 
> +#if defined(CONFIG_SYS_KW_SPI_MPP)
> +u32 spi_mpp_backup[4];
> +#endif
> +
>  int spi_claim_bus(struct spi_slave *slave)
>  {
> +#if defined(CONFIG_SYS_KW_SPI_MPP)
> +	u32 config;
> +	u32 spi_mpp_config[4];
> +
> +	config = CONFIG_SYS_KW_SPI_MPP;
> +
> +	if (config & MOSI_MPP6)
> +		spi_mpp_config[0] = MPP6_SPI_MOSI;
> +	else
> +		spi_mpp_config[0] = MPP1_SPI_MOSI;
> +
> +	if (config & SCK_MPP10)
> +		spi_mpp_config[1] = MPP10_SPI_SCK;
> +	else
> +		spi_mpp_config[1] = MPP2_SPI_SCK;
> +
> +	if (config & MISO_MPP11)
> +		spi_mpp_config[2] = MPP11_SPI_MISO;
> +	else
> +		spi_mpp_config[2] = MPP3_SPI_MISO;
> +
> +	spi_mpp_config[3] = 0;
> +	spi_mpp_backup[3] = 0;
> +
> +	/* save current mpp configuration */
> +	kirkwood_mpp_read(spi_mpp_config, spi_mpp_backup);
> +
> +	/* finally set chosen mpp spi configuration */
> +	kirkwood_mpp_conf(spi_mpp_config);
> +#endif
> +
>  	return 0;
>  }
> 
>  void spi_release_bus(struct spi_slave *slave)
>  {
> +#if defined(CONFIG_SYS_KW_SPI_MPP)
> +	kirkwood_mpp_conf(spi_mpp_backup);
> +#endif
>  }
> 

Acked-By: Prafulla Wadaskar <Prafulla at marvell.com>
One more comment: do you think we should safeguard spi_claim_bus for repeatative calls, for ex. once bus is claimed, it should be reclaimed until we release it?

Regards...
Prafulla . . .

>  #ifndef CONFIG_SPI_CS_IS_VALID
> --
> 1.7.1