[PATCH] mmc: add wp_grp_size node

[Bo Ye]

From: "lin.gui" <lin.gui at mediatek.com>

Detail:
Add node "wp_grp_size", corresponding to WP_GRP_SIZE
(write protect group size) of eMMC's CSD register.

Scenario:
The eMMC card can be set into write-protected mode to
prevent data from being accidentally modified or deleted.
Wp_grp_size (Write Protect Group Size) refers to an
attribute of the eMMC card, used to manage write protection,
and is the CSD register  [36:32] of the eMMC device.
Wp_grp_size (Write Protect Group Size) indicates how many
eMMC blocks are contained in each write protection group on the eMMC card.

Final rendered file:
"/sys/class/mmc_host/mmc0/mmc0:0001/wp_grp_size"

Signed-off-by: lin.gui <lin.gui at mediatek.com>
Change-Id: I73952dbde2db375ba918daadb3264380b7863096
---
 drivers/mmc/core/mmc.c   | 16 +++++++++++++++-
 include/linux/mmc/card.h |  2 ++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 4a4bab9aa726..9b67e49a9e63 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -136,6 +136,17 @@ static void mmc_set_erase_size(struct mmc_card *card)
 	mmc_init_erase(card);
 }
 
+
+static void mmc_set_wp_grp_size(struct mmc_card *card)
+{
+	if (card->ext_csd.erase_group_def & 1)
+		card->wp_grp_size = card->ext_csd.hc_erase_size *
+			card->ext_csd.raw_hc_erase_gap_size;
+	else
+		card->wp_grp_size = card->csd.erase_size *
+			(card->csd.wp_grp_size + 1);
+}
+
 /*
  * Given a 128-bit response, decode to our card CSD structure.
  */
@@ -186,6 +197,7 @@ static int mmc_decode_csd(struct mmc_card *card)
 		b = UNSTUFF_BITS(resp, 37, 5);
 		csd->erase_size = (a + 1) * (b + 1);
 		csd->erase_size <<= csd->write_blkbits - 9;
+		csd->wp_grp_size = UNSTUFF_BITS(resp, 32, 5);
 	}
 
 	return 0;
@@ -791,6 +803,7 @@ MMC_DEV_ATTR(csd, "%08x%08x%08x%08x\n", card->raw_csd[0], card->raw_csd[1],
 MMC_DEV_ATTR(date, "%02d/%04d\n", card->cid.month, card->cid.year);
 MMC_DEV_ATTR(erase_size, "%u\n", card->erase_size << 9);
 MMC_DEV_ATTR(preferred_erase_size, "%u\n", card->pref_erase << 9);
+MMC_DEV_ATTR(wp_grp_size, "%u\n", card->wp_grp_size << 9);
 MMC_DEV_ATTR(ffu_capable, "%d\n", card->ext_csd.ffu_capable);
 MMC_DEV_ATTR(hwrev, "0x%x\n", card->cid.hwrev);
 MMC_DEV_ATTR(manfid, "0x%06x\n", card->cid.manfid);
@@ -851,6 +864,7 @@ static struct attribute *mmc_std_attrs[] = {
 	&dev_attr_date.attr,
 	&dev_attr_erase_size.attr,
 	&dev_attr_preferred_erase_size.attr,
+	&dev_attr_wp_grp_size.attr,
 	&dev_attr_fwrev.attr,
 	&dev_attr_ffu_capable.attr,
 	&dev_attr_hwrev.attr,
@@ -1759,7 +1773,7 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
 			mmc_set_erase_size(card);
 		}
 	}
-
+	mmc_set_wp_grp_size(card);
 	/*
 	 * Ensure eMMC user default partition is enabled
 	 */
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index daa2f40d9ce6..62873ecc52f1 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -32,6 +32,7 @@ struct mmc_csd {
 	unsigned int		r2w_factor;
 	unsigned int		max_dtr;
 	unsigned int		erase_size;		/* In sectors */
+	unsigned int		wp_grp_size;
 	unsigned int		read_blkbits;
 	unsigned int		write_blkbits;
 	unsigned int		capacity;
@@ -304,6 +305,7 @@ struct mmc_card {
 	unsigned int		eg_boundary;	/* don't cross erase-group boundaries */
 	unsigned int		erase_arg;	/* erase / trim / discard */
  	u8			erased_byte;	/* value of erased bytes */
+	unsigned int		wp_grp_size; /* write group size in sectors */
 
 	u32			raw_cid[4];	/* raw card CID */
 	u32			raw_csd[4];	/* raw card CSD */
-- 
2.17.0