[PATCH 4/4] mmc: core: Read performance enhancements registers for SD cards

[Ulf Hansson <ulf.hansson@xxxxxxxxxx>]

In SD spec v6.x the SD function extension registers for performance
enhancements were introduced. These registers let the SD card announce
supports for various performance related features, like "self-maintenance",
"cache" and "command queuing".

Let's extend the parsing of SD function extension registers and store the
information in the struct mmc_card. This allows subsequent changes to
easier implement the complete support for new the performance enhancement
features.

Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
---
 drivers/mmc/core/sd.c    | 46 ++++++++++++++++++++++++++++++++++++++++
 include/linux/mmc/card.h |  7 ++++++
 2 files changed, 53 insertions(+)

diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index d6e838b7c895..0e946afd6d22 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -1063,6 +1063,48 @@ static int sd_decode_ext_reg_power(struct mmc_card *card, u8 fno, u32 reg_addr)
 	return 0;
 }
 
+static int sd_decode_ext_reg_perf(struct mmc_card *card, u8 fno, u32 reg_addr)
+{
+	int err;
+	u8 *reg_buf;
+
+	err = sd_read_ext_reg_fno(card, fno, reg_addr, &reg_buf);
+	if (err) {
+		pr_warn("%s: error %d reading PERF func of ext reg\n",
+			mmc_hostname(card->host), err);
+		return err;
+	}
+
+	/* PERF revision. */
+	card->ext_perf.rev = reg_buf[0];
+
+	/* FX_EVENT support at bit 0. */
+	if (reg_buf[1] & 0x1)
+		card->ext_perf.feature_support |= SD_EXT_PERF_FX_EVENT;
+
+	/* Card initiated self-maintenance support at bit 0. */
+	if (reg_buf[2] & 0x1)
+		card->ext_perf.feature_support |= SD_EXT_PERF_CARD_MAINT;
+
+	/* Host initiated self-maintenance support at bit 1. */
+	if (reg_buf[2] & 0x2)
+		card->ext_perf.feature_support |= SD_EXT_PERF_HOST_MAINT;
+
+	/* Cache support at bit 0. */
+	if (reg_buf[4] & 0x1)
+		card->ext_perf.feature_support |= SD_EXT_PERF_CACHE;
+
+	/* Command queue support indicated via queue depth bits (0 to 4). */
+	if (reg_buf[6] & 0x1f)
+		card->ext_perf.feature_support |= SD_EXT_PERF_CMD_QUEUE;
+
+	card->ext_perf.reg_addr = reg_addr;
+	card->ext_perf.fno = fno;
+
+	kfree(reg_buf);
+	return 0;
+}
+
 static int sd_decode_ext_reg(struct mmc_card *card, u8 *gen_info_buf,
 			     u16 *next_ext_addr)
 {
@@ -1103,6 +1145,10 @@ static int sd_decode_ext_reg(struct mmc_card *card, u8 *gen_info_buf,
 	if (sfc == 0x1)
 		return sd_decode_ext_reg_power(card, fno, reg_addr);
 
+	/* Standard Function Code for performance enhancement. */
+	if (sfc == 0x2)
+		return sd_decode_ext_reg_perf(card, fno, reg_addr);
+
 	return 0;
 }
 
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 6a1d64fba0f3..8e21eebe704d 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -200,6 +200,12 @@ struct sd_ext_reg {
 #define SD_EXT_POWER_OFF_NOTIFY	(1<<0)
 #define SD_EXT_POWER_SUSTENANCE	(1<<1)
 #define SD_EXT_POWER_DOWN_MODE	(1<<2)
+/* Performance Enhancement Function. */
+#define SD_EXT_PERF_FX_EVENT	(1<<0)
+#define SD_EXT_PERF_CARD_MAINT	(1<<1)
+#define SD_EXT_PERF_HOST_MAINT	(1<<2)
+#define SD_EXT_PERF_CACHE	(1<<3)
+#define SD_EXT_PERF_CMD_QUEUE	(1<<4)
 };
 
 struct sdio_cccr {
@@ -304,6 +310,7 @@ struct mmc_card {
 	struct sd_ssr		ssr;		/* yet more SD information */
 	struct sd_switch_caps	sw_caps;	/* switch (CMD6) caps */
 	struct sd_ext_reg	ext_power;	/* SD extension reg for PM */
+	struct sd_ext_reg	ext_perf;	/* SD extension reg for PERF */
 
 	unsigned int		sdio_funcs;	/* number of SDIO functions */
 	atomic_t		sdio_funcs_probed; /* number of probed SDIO funcs */
-- 
2.25.1