SD cards which conform to Physical Layer Spec v3.01 can support additional Bus Speed Modes, Driver Strength, and Current Limit other than the default values. We use CMD6 mode 0 to read these additional card functions. The values read here will be used during UHS-I initialization steps.
Signed-off-by: Arindam Nath <[email protected]> --- drivers/mmc/core/sd.c | 66 ++++++++++++++++++++++++++++++++++++++++----- include/linux/mmc/card.h | 3 ++ 2 files changed, 61 insertions(+), 8 deletions(-) diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c index b967588..eefa4aa 100644 --- a/drivers/mmc/core/sd.c +++ b/drivers/mmc/core/sd.c @@ -284,25 +284,75 @@ static int mmc_read_switch(struct mmc_card *card) return -ENOMEM; } + /* Find out the supported Bus Speed Modes. */ err = mmc_sd_switch(card, 0, 0, 1, status); if (err) { - /* If the host or the card can't do the switch, - * fail more gracefully. */ + /* + * If the host or the card can't do the switch, + * fail more gracefully. + */ if ((err != -EINVAL) - && (err != -ENOSYS) - && (err != -EFAULT)) + && (err != -ENOSYS) + && (err != -EFAULT)) goto out; - printk(KERN_WARNING "%s: problem reading switch " - "capabilities, performance might suffer.\n", + printk(KERN_WARNING "%s: problem reading Bus Speed modes.\n", mmc_hostname(card->host)); err = 0; goto out; } - if (status[13] & 0x02) - card->sw_caps.hs_max_dtr = 50000000; + if (card->scr.sda_spec3) { + card->sw_caps.sd3_bus_mode = status[13]; + + /* Find out Driver Strengths supported by the card */ + err = mmc_sd_switch(card, 0, 2, 1, status); + if (err) { + /* + * If the host or the card can't do the switch, + * fail more gracefully. + */ + if ((err != -EINVAL) + && (err != -ENOSYS) + && (err != -EFAULT)) + goto out; + + printk(KERN_WARNING "%s: problem reading " + "Driver Strength.\n", + mmc_hostname(card->host)); + err = 0; + + goto out; + } + + card->sw_caps.sd3_drv_type = status[9]; + + /* Find out Current Limits supported by the card */ + err = mmc_sd_switch(card, 0, 3, 1, status); + if (err) { + /* + * If the host or the card can't do the switch, + * fail more gracefully. + */ + if ((err != -EINVAL) + && (err != -ENOSYS) + && (err != -EFAULT)) + goto out; + + printk(KERN_WARNING "%s: problem reading " + "Current Limit.\n", + mmc_hostname(card->host)); + err = 0; + + goto out; + } + + card->sw_caps.sd3_curr_limit = status[7]; + } else { + if (status[13] & 0x02) + card->sw_caps.hs_max_dtr = 50000000; + } out: kfree(status); diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h index 86d9672..18b0334 100644 --- a/include/linux/mmc/card.h +++ b/include/linux/mmc/card.h @@ -84,6 +84,9 @@ struct sd_ssr { struct sd_switch_caps { unsigned int hs_max_dtr; + unsigned int sd3_bus_mode; + unsigned int sd3_drv_type; + unsigned int sd3_curr_limit; }; struct sdio_cccr { -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
