[PATCH v3] mmc: core: Optimize the mmc erase size alignment

[Baolin Wang <baolin.wang@linaro.org>]

Before issuing mmc_erase() function, users always have checked if it can
erase with mmc_can_erase/trim/discard() function, thus remove the redundant
erase checking in mmc_erase() function.

This patch also optimizes the erase start/end sector alignment with
round_up()/round_down() function, when erase command is MMC_ERASE_ARG.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
Changes since v2:
 - Add nr checking and other optimization in mmc_erase() function.

Changes since v1:
 - Add the alignment if card->erase_size is not power of 2.
---
 drivers/mmc/core/core.c |   82 ++++++++++++++++++++++++++++++-----------------
 1 file changed, 53 insertions(+), 29 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index e55cde6..52156d4 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -2202,6 +2202,51 @@ out:
 	return err;
 }
 
+static unsigned int mmc_align_erase_size(struct mmc_card *card,
+					 unsigned int *from,
+					 unsigned int *to,
+					 unsigned int nr)
+{
+	unsigned int from_new = *from, nr_new = nr, rem;
+
+	if (is_power_of_2(card->erase_size)) {
+		unsigned int temp = from_new;
+
+		from_new = round_up(temp, card->erase_size);
+		rem = from_new - temp;
+
+		if (nr_new > rem)
+			nr_new -= rem;
+		else
+			return 0;
+
+		nr_new = round_down(nr_new, card->erase_size);
+	} else {
+		rem = from_new % card->erase_size;
+		if (rem) {
+			rem = card->erase_size - rem;
+			from_new += rem;
+			if (nr_new > rem)
+				nr_new -= rem;
+			else
+				return 0;
+		}
+
+		rem = nr_new % card->erase_size;
+		if (rem)
+			nr_new -= rem;
+	}
+
+	if (nr_new == 0)
+		return 0;
+
+	/* 'from' and 'to' are inclusive */
+	*to = from_new + nr_new - 1;
+	*from = from_new;
+
+	return nr_new;
+}
+
 /**
  * mmc_erase - erase sectors.
  * @card: card to erase
@@ -2217,13 +2262,6 @@ int mmc_erase(struct mmc_card *card, unsigned int from, unsigned int nr,
 	unsigned int rem, to = from + nr;
 	int err;
 
-	if (!(card->host->caps & MMC_CAP_ERASE) ||
-	    !(card->csd.cmdclass & CCC_ERASE))
-		return -EOPNOTSUPP;
-
-	if (!card->erase_size)
-		return -EOPNOTSUPP;
-
 	if (mmc_card_sd(card) && arg != MMC_ERASE_ARG)
 		return -EOPNOTSUPP;
 
@@ -2240,31 +2278,17 @@ int mmc_erase(struct mmc_card *card, unsigned int from, unsigned int nr,
 			return -EINVAL;
 	}
 
-	if (arg == MMC_ERASE_ARG) {
-		rem = from % card->erase_size;
-		if (rem) {
-			rem = card->erase_size - rem;
-			from += rem;
-			if (nr > rem)
-				nr -= rem;
-			else
-				return 0;
-		}
-		rem = nr % card->erase_size;
-		if (rem)
-			nr -= rem;
-	}
-
 	if (nr == 0)
 		return 0;
 
-	to = from + nr;
-
-	if (to <= from)
-		return -EINVAL;
-
-	/* 'from' and 'to' are inclusive */
-	to -= 1;
+	if (arg == MMC_ERASE_ARG) {
+		nr = mmc_align_erase_size(card, &from, &to, nr);
+		if (nr == 0)
+			return 0;
+	} else {
+		/* 'from' and 'to' are inclusive */
+		to -= 1;
+	}
 
 	/*
 	 * Special case where only one erase-group fits in the timeout budget:
-- 
1.7.9.5