Subject: [PATCH 3/3] mmc: atmel-mci: add support for odd clock dividers

From: [email-masked] (Nicolas Ferre)
Date: Thu, 22 Mar 2012 15:48:48 +0100

On 03/21/2012 04:41 PM, ludovic.desroches at atmel.com :
> From: Ludovic Desroches <[email-masked]>
> 
> Add an odd clock divider capability available from v5xx. It also involves
> changing the clock divider calculation.

Also tell here that you have changed the way that the switch/case
directive has been implemented.

> Signed-off-by: Ludovic Desroches <[email-masked]>

Otherwise:
Acked-by: Nicolas Ferre <[email-masked]>

> ---
>  drivers/mmc/host/atmel-mci-regs.h |    1 +
>  drivers/mmc/host/atmel-mci.c      |   48 ++++++++++++++++++++++--------------
>  2 files changed, 30 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/mmc/host/atmel-mci-regs.h b/drivers/mmc/host/atmel-mci-regs.h
> index 000b3ad..787aba1 100644
> --- a/drivers/mmc/host/atmel-mci-regs.h
> +++ b/drivers/mmc/host/atmel-mci-regs.h
> @@ -31,6 +31,7 @@
>  # define ATMCI_MR_PDCFBYTE		(  1 << 13)	/* Force Byte Transfer */
>  # define ATMCI_MR_PDCPADV		(  1 << 14)	/* Padding Value */
>  # define ATMCI_MR_PDCMODE		(  1 << 15)	/* PDC-oriented Mode */
> +# define ATMCI_MR_CLKODD(x)		((x) << 16)	/* LSB of Clock Divider */
>  #define ATMCI_DTOR			0x0008	/* Data Timeout */
>  # define ATMCI_DTOCYC(x)		((x) <<  0)	/* Data Timeout Cycles */
>  # define ATMCI_DTOMUL(x)		((x) <<  4)	/* Data Timeout Multiplier */
> diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
> index 9dcb236..75e28c0 100644
> --- a/drivers/mmc/host/atmel-mci.c
> +++ b/drivers/mmc/host/atmel-mci.c
> @@ -76,6 +76,7 @@ struct atmel_mci_caps {
>  	bool    has_cstor_reg;
>  	bool    has_highspeed;
>  	bool    has_rwproof;
> +	bool	has_odd_clk_div;
>  };
>  
>  struct atmel_mci_dma {
> @@ -1124,16 +1125,27 @@ static void atmci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>  		}
>  
>  		/* Calculate clock divider */
> -		clkdiv = DIV_ROUND_UP(host->bus_hz, 2 * clock_min) - 1;
> -		if (clkdiv > 255) {
> -			dev_warn(&mmc->class_dev,
> -				"clock %u too slow; using %lu\n",
> -				clock_min, host->bus_hz / (2 * 256));
> -			clkdiv = 255;
> +		if (host->caps.has_odd_clk_div) {
> +			clkdiv = DIV_ROUND_UP(host->bus_hz, clock_min) - 2;
> +			if (clkdiv > 511) {
> +				dev_warn(&mmc->class_dev,
> +				         "clock %u too slow; using %lu\n",
> +				         clock_min, host->bus_hz / (511 + 2));
> +				clkdiv = 511;
> +			}
> +			host->mode_reg = ATMCI_MR_CLKDIV(clkdiv >> 1)
> +			                 | ATMCI_MR_CLKODD(clkdiv & 1);
> +		} else {
> +			clkdiv = DIV_ROUND_UP(host->bus_hz, 2 * clock_min) - 1;
> +			if (clkdiv > 255) {
> +				dev_warn(&mmc->class_dev,
> +				         "clock %u too slow; using %lu\n",
> +				         clock_min, host->bus_hz / (2 * 256));
> +				clkdiv = 255;
> +			}
> +			host->mode_reg = ATMCI_MR_CLKDIV(clkdiv);
>  		}
>  
> -		host->mode_reg = ATMCI_MR_CLKDIV(clkdiv);
> -
>  		/*
>  		 * WRPROOF and RDPROOF prevent overruns/underruns by
>  		 * stopping the clock when the FIFO is full/empty.
> @@ -2000,37 +2012,35 @@ static void __init atmci_get_cap(struct atmel_mci *host)
>  			"version: 0x%x\n", version);
>  
>  	host->caps.has_dma = 0;
> -	host->caps.has_pdc = 0;
> +	host->caps.has_pdc = 1;
>  	host->caps.has_cfg_reg = 0;
>  	host->caps.has_cstor_reg = 0;
>  	host->caps.has_highspeed = 0;
>  	host->caps.has_rwproof = 0;
> +	host->caps.has_odd_clk_div = 0;
>  
>  	/* keep only major version number */
>  	switch (version & 0xf00) {
> -	case 0x100:
> -		host->caps.has_pdc = 1;
> -		break;
> -	case 0x200:
> -		host->caps.has_pdc = 1;
> -		host->caps.has_rwproof = 1;
> -		break;
> -	case 0x300:
> -	case 0x400:
>  	case 0x500:
> +		host->caps.has_odd_clk_div = 1;
> +	case 0x400:
> +	case 0x300:
>  #ifdef CONFIG_AT_HDMAC
>  		host->caps.has_dma = 1;
>  #else
> -		host->caps.has_dma = 0;
>  		dev_info(&host->pdev->dev,
>  			"has dma capability but dma engine is not selected, then use pio\n");
>  #endif
> +		host->caps.has_pdc = 0;
>  		host->caps.has_cfg_reg = 1;
>  		host->caps.has_cstor_reg = 1;
>  		host->caps.has_highspeed = 1;
> +	case 0x200:
>  		host->caps.has_rwproof = 1;
> +	case 0x100:
>  		break;
>  	default:
> +		host->caps.has_pdc = 0;
>  		dev_warn(&host->pdev->dev,
>  				"Unmanaged mci version, set minimum capabilities\n");
>  		break;

-- 
Nicolas Ferre