From: "harish_kandiga@mentor.com" <harish_kandiga@mentor.com>
Date: Tue, 10 Apr 2018 12:30:31 +0530
Subject: mmc: core: Add a new quirk for limiting clock rate

Git-commit: ebc5a1bf4f2afc2f2b348320dcfb45a8c0ac3de5
Patch-mainline: v4.18-rc1
References: fate#326470

This patch adds a quirk to limit clock rate which
can be used to reduce the SDIO clock rate for some
chips with broken UHS.

Signed-off-by: Harish Jenny K N <harish_kandiga@mentor.com>
Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
 drivers/mmc/core/card.h  | 6 ++++++
 drivers/mmc/core/sdio.c  | 6 +++++-
 include/linux/mmc/card.h | 1 +
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/core/card.h b/drivers/mmc/core/card.h
index 9c821eedd156..1170feb8f969 100644
--- a/drivers/mmc/core/card.h
+++ b/drivers/mmc/core/card.h
@@ -149,6 +149,12 @@ static inline void __maybe_unused remove_quirk(struct mmc_card *card, int data)
 	card->quirks &= ~data;
 }
 
+static inline void __maybe_unused add_limit_rate_quirk(struct mmc_card *card,
+						       int data)
+{
+	card->quirk_max_rate = data;
+}
+
 /*
  * Quirk add/remove for MMC products.
  */
diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
index c599a628a387..24b510b743da 100644
--- a/drivers/mmc/core/sdio.c
+++ b/drivers/mmc/core/sdio.c
@@ -444,6 +444,7 @@ static int sdio_set_bus_speed_mode(struct mmc_card *card)
 	unsigned int bus_speed, timing;
 	int err;
 	unsigned char speed;
+	unsigned int max_rate;
 
 	/*
 	 * If the host doesn't support any of the UHS-I modes, fallback on
@@ -500,9 +501,12 @@ static int sdio_set_bus_speed_mode(struct mmc_card *card)
 	if (err)
 		return err;
 
+	max_rate = min_not_zero(card->quirk_max_rate,
+				card->sw_caps.uhs_max_dtr);
+
 	if (bus_speed) {
 		mmc_set_timing(card->host, timing);
-		mmc_set_clock(card->host, card->sw_caps.uhs_max_dtr);
+		mmc_set_clock(card->host, max_rate);
 	}
 
 	return 0;
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 279b39008a33..5ebc47855721 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -252,6 +252,7 @@ struct mmc_card {
 #define MMC_TYPE_SD_COMBO	3		/* SD combo (IO+mem) card */
 	unsigned int		state;		/* (our) card state */
 	unsigned int		quirks; 	/* card quirks */
+	unsigned int		quirk_max_rate;	/* max rate set by quirks */
 #define MMC_QUIRK_LENIENT_FN0	(1<<0)		/* allow SDIO FN0 writes outside of the VS CCCR range */
 #define MMC_QUIRK_BLKSZ_FOR_BYTE_MODE (1<<1)	/* use func->cur_blksize */
 						/* for byte mode */
-- 
2.11.0