linux-kernel - [PATCH v5 1/2] mmc: Add cache

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Date:   Sun, 25 Apr 2021 09:02:06 +0300
From:   Avri Altman <avri.altman@....com>
To:     Ulf Hansson <ulf.hansson@...aro.org>, linux-mmc@...r.kernel.org,
        Adrian Hunter <adrian.hunter@...el.com>
Cc:     linux-kernel@...r.kernel.org, Avri Altman <avri.altman@....com>
Subject: [PATCH v5 1/2] mmc: Add cache_enabled bus ops

Add a new bus ops callback ->cache_enabled() and implement it for the
mmc bus type.

>From the mmc block layer point of view, it would then mean that if the
callback isn't implemented, the cache ctrl isn't supported (which
would be the case for SD then).

Going forward, newer SD cards support both cache and command queueing
nowadays, which means that we need to make the code in the mmc block
layer more agnostic. To do that, we should use the bus_ops callbacks,
e.g. adding the ->flush_cache() callback in the near future.

Signed-off-by: Avri Altman <avri.altman@....com>
---
 drivers/mmc/core/core.h    | 9 +++++++++
 drivers/mmc/core/mmc.c     | 7 +++++++
 drivers/mmc/core/mmc_ops.c | 4 +---
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
index 8032451abaea..db3c9c68875d 100644
--- a/drivers/mmc/core/core.h
+++ b/drivers/mmc/core/core.h
@@ -29,6 +29,7 @@ struct mmc_bus_ops {
 	int (*shutdown)(struct mmc_host *);
 	int (*hw_reset)(struct mmc_host *);
 	int (*sw_reset)(struct mmc_host *);
+	bool (*cache_enabled)(struct mmc_host *);
 };
 
 void mmc_attach_bus(struct mmc_host *host, const struct mmc_bus_ops *ops);
@@ -163,4 +164,12 @@ static inline void mmc_post_req(struct mmc_host *host, struct mmc_request *mrq,
 		host->ops->post_req(host, mrq, err);
 }
 
+static inline bool mmc_cache_enabled(struct mmc_host *host)
+{
+	if (host->bus_ops->cache_enabled)
+		return host->bus_ops->cache_enabled(host);
+
+	return false;
+}
+
 #endif
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index d35231feac68..8674c3e0c02c 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -2029,6 +2029,12 @@ static void mmc_detect(struct mmc_host *host)
 	}
 }
 
+static bool _mmc_cache_enabled(struct mmc_host *host)
+{
+	return host->card->ext_csd.cache_size > 0 &&
+	       host->card->ext_csd.cache_ctrl & 1;
+}
+
 static int _mmc_suspend(struct mmc_host *host, bool is_suspend)
 {
 	int err = 0;
@@ -2208,6 +2214,7 @@ static const struct mmc_bus_ops mmc_ops = {
 	.alive = mmc_alive,
 	.shutdown = mmc_shutdown,
 	.hw_reset = _mmc_hw_reset,
+	.cache_enabled = _mmc_cache_enabled,
 };
 
 /*
diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
index cdf02d88fe92..5756781fef37 100644
--- a/drivers/mmc/core/mmc_ops.c
+++ b/drivers/mmc/core/mmc_ops.c
@@ -968,9 +968,7 @@ int mmc_flush_cache(struct mmc_card *card)
 {
 	int err = 0;
 
-	if (mmc_card_mmc(card) &&
-			(card->ext_csd.cache_size > 0) &&
-			(card->ext_csd.cache_ctrl & 1)) {
+	if (mmc_cache_enabled(card->host)) {
 		err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
 				 EXT_CSD_FLUSH_CACHE, 1,
 				 MMC_CACHE_FLUSH_TIMEOUT_MS);
-- 
2.25.1