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mmc: core: more fine-grained hooks for HS400 tuning

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This adds two new HS400 tuning operations:
* hs400_downgrade
* hs400_complete

These supplement the existing HS400 operation:
* prepare_hs400_tuning

This is motivated by a requirement of Renesas SDHI for the following:
1. Disabling SCC before selecting to HS if selection of HS400 has occurred.
   This can be done in an implementation of prepare_hs400_tuning_downgrade
2. Updating registers after switching to HS400
   This can be done in an implementation of complete_hs400_tuning

If hs400_downgrade or hs400_complete are not implemented then they are not
called. Thus means there should be no affect for existing drivers as none
implemt these ops.

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This commit is contained in:
Simon Horman 2018-06-18 14:57:49 +02:00 committed by Ulf Hansson
parent ecf7c7c585
commit ba6c7ac3a2
2 changed files with 17 additions and 0 deletions
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10
drivers/mmc/core/mmc.c
View File

@ -1169,6 +1169,10 @@ static int mmc_select_hs400(struct mmc_card *card)
/* Set host controller to HS timing */
mmc_set_timing(card->host, MMC_TIMING_MMC_HS);
/* Prepare host to downgrade to HS timing */
if (host->ops->hs400_downgrade)
host->ops->hs400_downgrade(host);
/* Reduce frequency to HS frequency */
max_dtr = card->ext_csd.hs_max_dtr;
mmc_set_clock(host, max_dtr);
@ -1209,6 +1213,9 @@ static int mmc_select_hs400(struct mmc_card *card)
if (err)
goto out_err;
if (host->ops->hs400_complete)
host->ops->hs400_complete(host);
return 0;
out_err:
@ -1256,6 +1263,9 @@ int mmc_hs400_to_hs200(struct mmc_card *card)
mmc_set_timing(host, MMC_TIMING_MMC_HS);
if (host->ops->hs400_downgrade)
host->ops->hs400_downgrade(host);
err = mmc_switch_status(card);
if (err)
goto out_err;

7
include/linux/mmc/host.h
View File

@ -146,6 +146,13 @@ struct mmc_host_ops {
/* Prepare HS400 target operating frequency depending host driver */
int (*prepare_hs400_tuning)(struct mmc_host *host, struct mmc_ios *ios);
/* Prepare for switching from HS400 to HS200 */
void (*hs400_downgrade)(struct mmc_host *host);
/* Complete selection of HS400 */
void (*hs400_complete)(struct mmc_host *host);
/* Prepare enhanced strobe depending host driver */
void (*hs400_enhanced_strobe)(struct mmc_host *host,
struct mmc_ios *ios);