This adds two new HS400 tuning operations: * prepare_hs400_tuning_downgrade * complete_hs400_tuning
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 After this patch the call sequence is as follows: * Initial tuning i. prepare_hs400_tuning 2. Tuning procedure 3. Select HS400 4. complete_hs400_tuning * Retune 1. prepare_hs400_tuning_downgrade 2. Select HS200 3. prepare_hs400_tuning 4. Tuning procedure 5. Select HS400 6. complete_hs400_tuning If prepare_hs400_tuning or complete_hs400_tuning are not implemented they are not called. And if neither are called the procedure is the same as before this patch. Design consideration: In the case of Renesas SDHI it is likely that prepare_hs400_tuning_downgrade and prepare_hs400_tuning could be combined if the latter was called before selecting HS200 during tuning. When I say likely, I believe it matches my understanding of the hardware. However, I did not test this as I am entirely unsure if moving the prepare_hs400_tuning call would work for other hardware that uses this operation and I am in no position to test such hardware. Signed-off-by: Simon Horman <[email protected]> --- v4 * New patch --- drivers/mmc/core/host.c | 13 ++++++++++++- drivers/mmc/core/mmc.c | 19 ++++++++++++++----- include/linux/mmc/host.h | 26 +++++++++++++++++++++++++- 3 files changed, 51 insertions(+), 7 deletions(-) diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c index 64b03d6eaf18..5e60df7ca11f 100644 --- a/drivers/mmc/core/host.c +++ b/drivers/mmc/core/host.c @@ -138,6 +138,10 @@ int mmc_retune(struct mmc_host *host) host->doing_retune = 1; if (host->ios.timing == MMC_TIMING_MMC_HS400) { + if (host->ops->prepare_hs400_tuning_downgrade) + host->ops->prepare_hs400_tuning_downgrade(host, + &host->ios); + err = mmc_hs400_to_hs200(host->card); if (err) goto out; @@ -152,8 +156,15 @@ int mmc_retune(struct mmc_host *host) if (err) goto out; - if (return_to_hs400) + if (return_to_hs400) { err = mmc_hs200_to_hs400(host->card); + if (err) + goto out; + + if (host->ops->complete_hs400_tuning) + host->ops->complete_hs400_tuning(host, &host->ios); + } + out: host->doing_retune = 0; diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index 099b327e10ca..a108a1a3e27f 100644 --- a/drivers/mmc/core/mmc.c +++ b/drivers/mmc/core/mmc.c @@ -1508,22 +1508,31 @@ static int mmc_select_timing(struct mmc_card *card) static int mmc_hs200_tuning(struct mmc_card *card) { struct mmc_host *host = card->host; + bool run_hs400_ops; int err; + run_hs400_ops = card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400 && + host->ios.bus_width == MMC_BUS_WIDTH_8; + /* * Timing should be adjusted to the HS400 target * operation frequency for tuning process */ - if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400 && - host->ios.bus_width == MMC_BUS_WIDTH_8) - if (host->ops->prepare_hs400_tuning) - host->ops->prepare_hs400_tuning(host, &host->ios); + if (run_hs400_ops && host->ops->prepare_hs400_tuning) + host->ops->prepare_hs400_tuning(host, &host->ios); err = mmc_execute_tuning(card); if (err) return err; - return mmc_select_hs400(card); + err = mmc_select_hs400(card); + if (err) + return err; + + if (run_hs400_ops && host->ops->complete_hs400_tuning) + host->ops->complete_hs400_tuning(host, &host->ios); + + return 0; } /* diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index 85146235231e..5d3ae1071d2f 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -143,8 +143,32 @@ struct mmc_host_ops { /* The tuning command opcode value is different for SD and eMMC cards */ int (*execute_tuning)(struct mmc_host *host, u32 opcode); - /* Prepare HS400 target operating frequency depending host driver */ + /* Prepare for HS400 downgrade during tuning of target operating frequency depending on host driver + * If provided and retuning is in progress, this is called before: + * 1. Switching from HS400 to HS200; which preceeds + * 2. Calling .prepare_hs400_tuning, if present; which preceeds + * 3. The HS400 tuning procedure + */ + void (*prepare_hs400_tuning_downgrade)(struct mmc_host *host, struct mmc_ios *ios); + + /* Prepare for tuning HS400 target operating frequency depending on host driver + * If provided, this called: + * - In the case that retuning is in progress, after: + * 1. .prepare_hs400_tuning_downgrade(), if present + * 2. Switching from HS400 to HS200 + * - And in any case before: + * 3. The HS400 tuning procedure + */ + int (*prepare_hs400_tuning)(struct mmc_host *host, struct mmc_ios *ios); + + /* Complete tuning HS400 target operating frequency depending host driver + * If provided, this is called after: + * 1. The HS400 tuning procedure + * 2. Switching from HS200 to HS400 + */ + void (*complete_hs400_tuning)(struct mmc_host *host, struct mmc_ios *ios); + /* Prepare enhanced strobe depending host driver */ void (*hs400_enhanced_strobe)(struct mmc_host *host, struct mmc_ios *ios); -- 2.11.0
