On Thu, May 5, 2011 at 2:49 AM, Arindam Nath <arindam.nath@xxxxxxx> wrote:
> We decide on the current limit to be set for the card based on the
> Capability of Host Controller to provide current at 1.8V signalling,
> and the maximum current limit of the card as indicated by CMD6
> mode 0. We then set the current limit for the card using CMD6 mode 1.
> As per the Physical Layer Spec v3.01, the current limit switch is
> only applicable for SDR50, SDR104, and DDR50 bus speed modes. For
> other UHS-I modes, we set the default current limit of 200mA.
>
> Signed-off-by: Arindam Nath <arindam.nath@xxxxxxx>
> Reviewed-by: Philip Rakity <prakity@xxxxxxxxxxx>
> Tested-by: Philip Rakity <prakity@xxxxxxxxxxx>
Acked-by: Zhangfei Gao<zhangfei.gao@xxxxxxxxxxx>
Verified with Toshiba uhs card and general hs card, on mmp2 in SDMA mode.
> ---
> drivers/mmc/core/sd.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++
> drivers/mmc/host/sdhci.c | 10 +++++++
> include/linux/mmc/card.h | 9 ++++++
> include/linux/mmc/host.h | 4 +++
> 4 files changed, 86 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
> index 0491978..9270d82 100644
> --- a/drivers/mmc/core/sd.c
> +++ b/drivers/mmc/core/sd.c
> @@ -517,6 +517,64 @@ static int sd_set_bus_speed_mode(struct mmc_card *card, u8 *status)
> return 0;
> }
>
> +static int sd_set_current_limit(struct mmc_card *card, u8 *status)
> +{
> + int current_limit = 0;
> + int err;
> +
> + /*
> + * Current limit switch is only defined for SDR50, SDR104, and DDR50
> + * bus speed modes. For other bus speed modes, we set the default
> + * current limit of 200mA.
> + */
> + if ((card->sd_bus_speed == UHS_SDR50_BUS_SPEED) ||
> + (card->sd_bus_speed == UHS_SDR104_BUS_SPEED) ||
> + (card->sd_bus_speed == UHS_DDR50_BUS_SPEED)) {
> + if (card->host->caps & MMC_CAP_MAX_CURRENT_800) {
> + if (card->sw_caps.sd3_curr_limit & SD_MAX_CURRENT_800)
> + current_limit = SD_SET_CURRENT_LIMIT_800;
> + else if (card->sw_caps.sd3_curr_limit &
> + SD_MAX_CURRENT_600)
> + current_limit = SD_SET_CURRENT_LIMIT_600;
> + else if (card->sw_caps.sd3_curr_limit &
> + SD_MAX_CURRENT_400)
> + current_limit = SD_SET_CURRENT_LIMIT_400;
> + else if (card->sw_caps.sd3_curr_limit &
> + SD_MAX_CURRENT_200)
> + current_limit = SD_SET_CURRENT_LIMIT_200;
> + } else if (card->host->caps & MMC_CAP_MAX_CURRENT_600) {
> + if (card->sw_caps.sd3_curr_limit & SD_MAX_CURRENT_600)
> + current_limit = SD_SET_CURRENT_LIMIT_600;
> + else if (card->sw_caps.sd3_curr_limit &
> + SD_MAX_CURRENT_400)
> + current_limit = SD_SET_CURRENT_LIMIT_400;
> + else if (card->sw_caps.sd3_curr_limit &
> + SD_MAX_CURRENT_200)
> + current_limit = SD_SET_CURRENT_LIMIT_200;
> + } else if (card->host->caps & MMC_CAP_MAX_CURRENT_400) {
> + if (card->sw_caps.sd3_curr_limit & SD_MAX_CURRENT_400)
> + current_limit = SD_SET_CURRENT_LIMIT_400;
> + else if (card->sw_caps.sd3_curr_limit &
> + SD_MAX_CURRENT_200)
> + current_limit = SD_SET_CURRENT_LIMIT_200;
> + } else if (card->host->caps & MMC_CAP_MAX_CURRENT_200) {
> + if (card->sw_caps.sd3_curr_limit & SD_MAX_CURRENT_200)
> + current_limit = SD_SET_CURRENT_LIMIT_200;
> + }
> + } else
> + current_limit = SD_SET_CURRENT_LIMIT_200;
> +
> + err = mmc_sd_switch(card, 1, 3, current_limit, status);
> + if (err)
> + return err;
> +
> + if (((status[15] >> 4) & 0x0F) != current_limit)
> + printk(KERN_WARNING "%s: Problem setting current limit!\n",
> + mmc_hostname(card->host));
> +
> + return 0;
> +}
> +
> /*
> * UHS-I specific initialization procedure
> */
> @@ -555,6 +613,11 @@ static int mmc_sd_init_uhs_card(struct mmc_card *card)
>
> /* Set bus speed mode of the card */
> err = sd_set_bus_speed_mode(card, status);
> + if (err)
> + goto out;
> +
> + /* Set current limit for the card */
> + err = sd_set_current_limit(card, status);
>
> out:
> kfree(status);
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index de7e6e9..9176911 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2217,6 +2217,16 @@ int sdhci_add_host(struct sdhci_host *host)
>
> if (max_current_180 > 150)
> mmc->caps |= MMC_CAP_SET_XPC_180;
> +
> + /* Maximum current capabilities of the host at 1.8V */
> + if (max_current_180 >= 800)
> + mmc->caps |= MMC_CAP_MAX_CURRENT_800;
> + else if (max_current_180 >= 600)
> + mmc->caps |= MMC_CAP_MAX_CURRENT_600;
> + else if (max_current_180 >= 400)
> + mmc->caps |= MMC_CAP_MAX_CURRENT_400;
> + else
> + mmc->caps |= MMC_CAP_MAX_CURRENT_200;
> }
>
> mmc->ocr_avail = ocr_avail;
> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> index 4ef6ded..47b5ad3 100644
> --- a/include/linux/mmc/card.h
> +++ b/include/linux/mmc/card.h
> @@ -105,6 +105,15 @@ struct sd_switch_caps {
> #define SD_DRIVER_TYPE_C 0x04
> #define SD_DRIVER_TYPE_D 0x08
> unsigned int sd3_curr_limit;
> +#define SD_SET_CURRENT_LIMIT_200 0
> +#define SD_SET_CURRENT_LIMIT_400 1
> +#define SD_SET_CURRENT_LIMIT_600 2
> +#define SD_SET_CURRENT_LIMIT_800 3
> +
> +#define SD_MAX_CURRENT_200 (1 << SD_SET_CURRENT_LIMIT_200)
> +#define SD_MAX_CURRENT_400 (1 << SD_SET_CURRENT_LIMIT_400)
> +#define SD_MAX_CURRENT_600 (1 << SD_SET_CURRENT_LIMIT_600)
> +#define SD_MAX_CURRENT_800 (1 << SD_SET_CURRENT_LIMIT_800)
> };
>
> struct sdio_cccr {
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index 6237599..52b5dc9 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -203,6 +203,10 @@ struct mmc_host {
> #define MMC_CAP_DRIVER_TYPE_A (1 << 23) /* Host supports Driver Type A */
> #define MMC_CAP_DRIVER_TYPE_C (1 << 24) /* Host supports Driver Type C */
> #define MMC_CAP_DRIVER_TYPE_D (1 << 25) /* Host supports Driver Type D */
> +#define MMC_CAP_MAX_CURRENT_200 (1 << 26) /* Host max current limit is 200mA */
> +#define MMC_CAP_MAX_CURRENT_400 (1 << 27) /* Host max current limit is 400mA */
> +#define MMC_CAP_MAX_CURRENT_600 (1 << 28) /* Host max current limit is 600mA */
> +#define MMC_CAP_MAX_CURRENT_800 (1 << 29) /* Host max current limit is 800mA */
>
> mmc_pm_flag_t pm_caps; /* supported pm features */
>
> --
> 1.7.1
>
>
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