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Commit 0c758bb6 authored by Asutosh Das's avatar Asutosh Das Committed by Subhash Jadavani
Browse files

mmc: core: add clock-scaling support to HS400 cards 



This patch adds clock scaling support to HS400 cards.
Scaling down to 52MHz from HS400 involves:
 - switching the bus-speed mode to HS at 52MHz

Scaling up to HS400 would require all of the initialization
process upto HS400 mode selection.

Change-Id: I8196d6666bcc0ef327659253df53a17792fa51f7
Signed-off-by: default avatarAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: default avatarKrishna Konda <kkonda@codeaurora.org>
[venkatg@codeaurora.org: fix mmc_select_hs args and MAX_DTRs
as used in 3.14 kernel]
Signed-off-by: default avatarVenkat Gopalakrishnan <venkatg@codeaurora.org>
[subhashj@codeaurora.org: fixed merge conflicts]
Signed-off-by: default avatarSubhash Jadavani <subhashj@codeaurora.org>
parent 3f3e47cf

drivers/mmc/core/core.c

+13 −1
Original line number Diff line number Diff line
@@ -2689,13 +2689,19 @@ EXPORT_SYMBOL_GPL(mmc_reset_clk_scale_stats); 
unsigned long mmc_get_max_frequency(struct mmc_host *host)

{

	unsigned long freq;

	unsigned char timing;



	if (host->ops && host->ops->get_max_frequency) {

		freq = host->ops->get_max_frequency(host);

		goto out;

	}



	switch (host->ios.timing) {

	if (mmc_card_hs400(host->card))

		timing = MMC_TIMING_MMC_HS400;

	else

		timing = host->ios.timing;



	switch (timing) {

	case MMC_TIMING_UHS_SDR50:

		freq = UHS_SDR50_MAX_DTR;

		break;
@@ -2708,6 +2714,9 @@ unsigned long mmc_get_max_frequency(struct mmc_host *host) 
	case MMC_TIMING_UHS_DDR50:

		freq = UHS_DDR50_MAX_DTR;

		break;

	case MMC_TIMING_MMC_HS400:

		freq = MMC_HS200_MAX_DTR;

		break;

	default:

		mmc_host_clk_hold(host);

		freq = host->ios.clock;
@@ -2748,6 +2757,9 @@ static unsigned long mmc_get_min_frequency(struct mmc_host *host) 
	case MMC_TIMING_MMC_HS200:

		freq = MMC_HIGH_52_MAX_DTR;

		break;

	case MMC_TIMING_MMC_HS400:

		freq = MMC_HIGH_52_MAX_DTR;

		break;

	case MMC_TIMING_UHS_DDR50:

		freq = UHS_DDR50_MAX_DTR / 2;

		break;

drivers/mmc/core/mmc.c

+28 −1
Original line number Diff line number Diff line
@@ -624,6 +624,7 @@ static int mmc_read_ext_csd(struct mmc_card *card) 
		return err;

	}



	memcpy(&card->cached_ext_csd, ext_csd, sizeof(card->ext_csd));

	err = mmc_decode_ext_csd(card, ext_csd);

	kfree(ext_csd);

	return err;
@@ -1299,6 +1300,26 @@ err: 
	return err;

}



int mmc_set_clock_bus_speed(struct mmc_card *card, unsigned long freq)

{

	int err;



	if (freq < MMC_HS200_MAX_DTR) {

		/*

		 * Lower the clock and adjust the timing to be able

		 * to switch to HighSpeed mode

		 */

		mmc_set_timing(card->host, MMC_TIMING_LEGACY);

		mmc_set_clock(card->host, MMC_HIGH_26_MAX_DTR);



		err = mmc_select_hs(card);

	} else {

		err = mmc_select_hs400(card);

	}



	return err;

}



/**

 * mmc_change_bus_speed() - Change MMC card bus frequency at runtime

 * @host: pointer to mmc host structure
@@ -1340,7 +1361,13 @@ static int mmc_change_bus_speed(struct mmc_host *host, unsigned long *freq) 
	if (*freq < host->f_min)

		*freq = host->f_min;



	if (mmc_card_hs400(card)) {

		err = mmc_set_clock_bus_speed(card, *freq);

		if (err)

			goto out;

	} else {

		mmc_set_clock(host, (unsigned int) (*freq));

	}



	if (mmc_card_hs200(card) && card->host->ops->execute_tuning) {

		/*

include/linux/mmc/card.h

+1 −0
Original line number Diff line number Diff line
@@ -345,6 +345,7 @@ struct mmc_card { 
	struct mmc_wr_pack_stats wr_pack_stats; /* packed commands stats*/

	struct notifier_block        reboot_notify;

	bool issue_long_pon;

	u8 cached_ext_csd;

};



/*