On Mar 4, 2011, at 3:32 AM, Arindam Nath 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.
>
> Signed-off-by: Arindam Nath <arindam.nath@xxxxxxx>
> ---
> drivers/mmc/core/sd.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
> drivers/mmc/host/sdhci.c | 24 ++++++++++++++++++++++++
> include/linux/mmc/card.h | 9 +++++++++
> include/linux/mmc/host.h | 1 +
> 4 files changed, 79 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
> index ec0d8e6..df98a2c 100644
> --- a/drivers/mmc/core/sd.c
> +++ b/drivers/mmc/core/sd.c
> @@ -550,6 +550,46 @@ 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)
> +{
> + struct mmc_host *host = card->host;
> + int mmc_host_max_current_180, current_limit;
> + int err;
> +
> + /* sanity check */
> + if (!host->ops->get_max_current_180)
> + return 0;
> +
> + /* Maximum current supported by host at 1.8V */
> + mmc_host_max_current_180 = host->ops->get_max_current_180(host);
> +
> + if (mmc_host_max_current_180 >= 800) {
> + if (card->sw_caps.uhs_curr_limit & SD_MAX_CURRENT_800)
> + current_limit = SD_SET_CURRENT_LIMIT_800;
> + else if (card->sw_caps.uhs_curr_limit & SD_MAX_CURRENT_600)
> + current_limit = SD_SET_CURRENT_LIMIT_600;
> + else if (card->sw_caps.uhs_curr_limit & SD_MAX_CURRENT_400)
> + current_limit = SD_SET_CURRENT_LIMIT_400;
> + } else if (mmc_host_max_current_180 >= 600) {
> + if (card->sw_caps.uhs_curr_limit & SD_MAX_CURRENT_600)
> + current_limit = SD_SET_CURRENT_LIMIT_600;
> + else if (card->sw_caps.uhs_curr_limit & SD_MAX_CURRENT_400)
> + current_limit = SD_SET_CURRENT_LIMIT_400;
> + } else if (mmc_host_max_current_180 >= 400)
> + if (card->sw_caps.uhs_curr_limit & SD_MAX_CURRENT_400)
> + current_limit = SD_SET_CURRENT_LIMIT_400;
> +
> + 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;
> +}
> +
warning on current_limit may not be initialized.
> /*
> * UHS-I specific initialization procedure
> */
> @@ -590,6 +630,11 @@ 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 f127fa2..245cc39 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -1462,12 +1462,36 @@ static int sdhci_start_signal_voltage_switch(struct mmc_host *mmc)
> return -EAGAIN;
> }
>
> +static int sdhci_get_max_current_180(struct mmc_host *mmc)
> +{
> + struct sdhci_host *host;
> + u32 max_current_caps;
> + unsigned long flags;
> + int max_current_180;
> +
> + host = mmc_priv(mmc);
> +
> + spin_lock_irqsave(&host->lock, flags);
> +
> + max_current_caps = sdhci_readl(host, SDHCI_MAX_CURRENT);
> +
> + spin_unlock_irqrestore(&host->lock, flags);
> +
> + /* Maximum current is 4 times the register value for 1.8V */
> + max_current_180 = ((max_current_caps & SDHCI_MAX_CURRENT_180_MASK) >>
> + SDHCI_MAX_CURRENT_180_SHIFT) *
> + SDHCI_MAX_CURRENT_MULTIPLIER;
> +
> + return max_current_180;
> +}
> +
> static const struct mmc_host_ops sdhci_ops = {
> .request = sdhci_request,
> .set_ios = sdhci_set_ios,
> .get_ro = sdhci_get_ro,
> .enable_sdio_irq = sdhci_enable_sdio_irq,
> .start_signal_voltage_switch = sdhci_start_signal_voltage_switch,
> + .get_max_current_180 = sdhci_get_max_current_180,
> };
>
> /*****************************************************************************\
> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> index 0b24c41..a6811ae 100644
> --- a/include/linux/mmc/card.h
> +++ b/include/linux/mmc/card.h
> @@ -98,6 +98,15 @@ struct sd_switch_caps {
> #define SD_DRIVER_TYPE_C 0x04
> #define SD_DRIVER_TYPE_D 0x08
> unsigned int uhs_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 4dfff6d..e84cd05 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -128,6 +128,7 @@ struct mmc_host_ops {
> void (*init_card)(struct mmc_host *host, struct mmc_card *card);
>
> int (*start_signal_voltage_switch)(struct mmc_host *host);
> + int (*get_max_current_180)(struct mmc_host *mmc);
> };
>
> struct mmc_card;
> --
> 1.7.1
>
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