mmc: core: Read performance enhancements registers for SD cards

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 prepares for subsequent changes to
implement the complete support for new the performance enhancement
features.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>
Link: https://lore.kernel.org/r/20210504161222.101536-11-ulf.hansson@linaro.org

drivers/mmc/core/sd.c

@@ -1058,6 +1058,55 @@ static int sd_parse_ext_reg_power(struct mmc_card *card, u8 fno, u8 page,
 	return err;
 }
 
+static int sd_parse_ext_reg_perf(struct mmc_card *card, u8 fno, u8 page,
+				 u16 offset)
+{
+	int err;
+	u8 *reg_buf;
+
+	reg_buf = kzalloc(512, GFP_KERNEL);
+	if (!reg_buf)
+		return -ENOMEM;
+
+	err = sd_read_ext_reg(card, fno, page, offset, 512, reg_buf);
+	if (err) {
+		pr_warn("%s: error %d reading PERF func of ext reg\n",
+			mmc_hostname(card->host), err);
+		goto out;
+	}
+
+	/* PERF revision. */
+	card->ext_perf.rev = reg_buf[0];
+
+	/* FX_EVENT support at bit 0. */
+	if (reg_buf[1] & BIT(0))
+		card->ext_perf.feature_support |= SD_EXT_PERF_FX_EVENT;
+
+	/* Card initiated self-maintenance support at bit 0. */
+	if (reg_buf[2] & BIT(0))
+		card->ext_perf.feature_support |= SD_EXT_PERF_CARD_MAINT;
+
+	/* Host initiated self-maintenance support at bit 1. */
+	if (reg_buf[2] & BIT(1))
+		card->ext_perf.feature_support |= SD_EXT_PERF_HOST_MAINT;
+
+	/* Cache support at bit 0. */
+	if (reg_buf[4] & BIT(0))
+		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.fno = fno;
+	card->ext_perf.page = page;
+	card->ext_perf.offset = offset;
+
+out:
+	kfree(reg_buf);
+	return err;
+}
+
 static int sd_parse_ext_reg(struct mmc_card *card, u8 *gen_info_buf,
 			    u16 *next_ext_addr)
 {
@@ -1102,6 +1151,10 @@ static int sd_parse_ext_reg(struct mmc_card *card, u8 *gen_info_buf,
 	if (sfc == 0x1)
 		return sd_parse_ext_reg_power(card, fno, page, offset);
 
+	/* Standard Function Code for performance enhancement. */
+	if (sfc == 0x2)
+		return sd_parse_ext_reg_perf(card, fno, page, offset);
+
 	return 0;
 }
 

include/linux/mmc/card.h

@@ -201,6 +201,12 @@ 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 {
@@ -305,6 +311,7 @@ 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 */