mmc: sd: Export SD Status via “ssr” device attribute

The SD Status register contains several important fields related to the
SD Card proprietary features.
Those fields may be used by user space applications for vendor specific
usage.
None of those fields are exported today by the driver to user space.
In this patch, we are reading the SD Status register and exporting
(using MMC_DEV_ATTR) the SD Status register to the user space.

Signed-off-by: Uri Yanai <uri.yanai@sandisk.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/core/sd.c

@@ -223,8 +223,7 @@ static int mmc_decode_scr(struct mmc_card *card)
 static int mmc_read_ssr(struct mmc_card *card)
 {
 	unsigned int au, es, et, eo;
-	int err, i;
-	u32 *ssr;
+	int i;
 
 	if (!(card->csd.cmdclass & CCC_APP_SPEC)) {
 		pr_warn("%s: card lacks mandatory SD Status function\n",
@@ -232,33 +231,27 @@ static int mmc_read_ssr(struct mmc_card *card)
 		return 0;
 	}
 
-	ssr = kmalloc(64, GFP_KERNEL);
-	if (!ssr)
-		return -ENOMEM;
-
-	err = mmc_app_sd_status(card, ssr);
-	if (err) {
+	if (mmc_app_sd_status(card, card->raw_ssr)) {
 		pr_warn("%s: problem reading SD Status register\n",
 			mmc_hostname(card->host));
-		err = 0;
-		goto out;
+		return 0;
 	}
 
 	for (i = 0; i < 16; i++)
-		ssr[i] = be32_to_cpu(ssr[i]);
+		card->raw_ssr[i] = be32_to_cpu(card->raw_ssr[i]);
 
 	/*
 	 * UNSTUFF_BITS only works with four u32s so we have to offset the
 	 * bitfield positions accordingly.
 	 */
-	au = UNSTUFF_BITS(ssr, 428 - 384, 4);
+	au = UNSTUFF_BITS(card->raw_ssr, 428 - 384, 4);
 	if (au) {
 		if (au <= 9 || card->scr.sda_spec3) {
 			card->ssr.au = sd_au_size[au];
-			es = UNSTUFF_BITS(ssr, 408 - 384, 16);
-			et = UNSTUFF_BITS(ssr, 402 - 384, 6);
+			es = UNSTUFF_BITS(card->raw_ssr, 408 - 384, 16);
+			et = UNSTUFF_BITS(card->raw_ssr, 402 - 384, 6);
 			if (es && et) {
-				eo = UNSTUFF_BITS(ssr, 400 - 384, 2);
+				eo = UNSTUFF_BITS(card->raw_ssr, 400 - 384, 2);
 				card->ssr.erase_timeout = (et * 1000) / es;
 				card->ssr.erase_offset = eo * 1000;
 			}
@@ -267,9 +260,8 @@ static int mmc_read_ssr(struct mmc_card *card)
 				mmc_hostname(card->host));
 		}
 	}
-out:
-	kfree(ssr);
-	return err;
+
+	return 0;
 }
 
 /*
@@ -666,6 +658,14 @@ MMC_DEV_ATTR(cid, "%08x%08x%08x%08x\n", card->raw_cid[0], card->raw_cid[1],
 MMC_DEV_ATTR(csd, "%08x%08x%08x%08x\n", card->raw_csd[0], card->raw_csd[1],
 	card->raw_csd[2], card->raw_csd[3]);
 MMC_DEV_ATTR(scr, "%08x%08x\n", card->raw_scr[0], card->raw_scr[1]);
+MMC_DEV_ATTR(ssr,
+	"%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x\n",
+		card->raw_ssr[0], card->raw_ssr[1], card->raw_ssr[2],
+		card->raw_ssr[3], card->raw_ssr[4], card->raw_ssr[5],
+		card->raw_ssr[6], card->raw_ssr[7], card->raw_ssr[8],
+		card->raw_ssr[9], card->raw_ssr[10], card->raw_ssr[11],
+		card->raw_ssr[12], card->raw_ssr[13], card->raw_ssr[14],
+		card->raw_ssr[15]);
 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);
@@ -698,6 +698,7 @@ static struct attribute *sd_std_attrs[] = {
 	&dev_attr_cid.attr,
 	&dev_attr_csd.attr,
 	&dev_attr_scr.attr,
+	&dev_attr_ssr.attr,
 	&dev_attr_date.attr,
 	&dev_attr_erase_size.attr,
 	&dev_attr_preferred_erase_size.attr,

include/linux/mmc/card.h

@@ -292,6 +292,7 @@ struct mmc_card {
 	u32			raw_cid[4];	/* raw card CID */
 	u32			raw_csd[4];	/* raw card CSD */
 	u32			raw_scr[2];	/* raw card SCR */
+	u32			raw_ssr[16];	/* raw card SSR */
 	struct mmc_cid		cid;		/* card identification */
 	struct mmc_csd		csd;		/* card specific */
 	struct mmc_ext_csd	ext_csd;	/* mmc v4 extended card specific */