mmc: add API to do eMMC hardware partitioning

This adds an API to do hardware partitioning on eMMC devices. The
new mmc_hwpart_config() function does the partitioning in one go.
As the different attributes and partitioning options on eMMC may
be interdependent validation has to be done based on the complete
partitioning configuration. The function accepts three modes:

- MMC_HWPART_CONF_CHECK: just validates that the configuration
  is valid.
- MMC_HWPART_CONF_SET: validates and sets all the fields in
  EXT_CSD but without setting the "partitioning completed" bit,
  and thus is reversible.
- MMC_HWPART_CONF_COMPLETE: does everything and is thus not
  reversible.

Signed-off-by: Diego Santa Cruz <Diego.SantaCruz@spinetix.com>

drivers/mmc/mmc.c

@@ -605,6 +605,161 @@ int mmc_switch_part(int dev_num, unsigned int part_num)
 	return ret;
 }
 
+int mmc_hwpart_config(struct mmc *mmc,
+		      const struct mmc_hwpart_conf *conf,
+		      enum mmc_hwpart_conf_mode mode)
+{
+	u8 part_attrs = 0;
+	u32 enh_size_mult;
+	u32 enh_start_addr;
+	u32 gp_size_mult[4];
+	u32 max_enh_size_mult;
+	u32 tot_enh_size_mult = 0;
+	int i, pidx, err;
+	ALLOC_CACHE_ALIGN_BUFFER(u8, ext_csd, MMC_MAX_BLOCK_LEN);
+
+	if (mode < MMC_HWPART_CONF_CHECK || mode > MMC_HWPART_CONF_COMPLETE)
+		return -EINVAL;
+
+	if (IS_SD(mmc) || (mmc->version < MMC_VERSION_4_41)) {
+		printf("eMMC >= 4.4 required for enhanced user data area\n");
+		return -EMEDIUMTYPE;
+	}
+
+	if (!(mmc->part_support & PART_SUPPORT)) {
+		printf("Card does not support partitioning\n");
+		return -EMEDIUMTYPE;
+	}
+
+	if (!mmc->hc_wp_grp_size) {
+		printf("Card does not define HC WP group size\n");
+		return -EMEDIUMTYPE;
+	}
+
+	/* check partition alignment and total enhanced size */
+	if (conf->user.enh_size) {
+		if (conf->user.enh_size % mmc->hc_wp_grp_size ||
+		    conf->user.enh_start % mmc->hc_wp_grp_size) {
+			printf("User data enhanced area not HC WP group "
+			       "size aligned\n");
+			return -EINVAL;
+		}
+		part_attrs |= EXT_CSD_ENH_USR;
+		enh_size_mult = conf->user.enh_size / mmc->hc_wp_grp_size;
+		if (mmc->high_capacity) {
+			enh_start_addr = conf->user.enh_start;
+		} else {
+			enh_start_addr = (conf->user.enh_start << 9);
+		}
+	} else {
+		enh_size_mult = 0;
+		enh_start_addr = 0;
+	}
+	tot_enh_size_mult += enh_size_mult;
+
+	for (pidx = 0; pidx < 4; pidx++) {
+		if (conf->gp_part[pidx].size % mmc->hc_wp_grp_size) {
+			printf("GP%i partition not HC WP group size "
+			       "aligned\n", pidx+1);
+			return -EINVAL;
+		}
+		gp_size_mult[pidx] = conf->gp_part[pidx].size / mmc->hc_wp_grp_size;
+		if (conf->gp_part[pidx].size && conf->gp_part[pidx].enhanced) {
+			part_attrs |= EXT_CSD_ENH_GP(pidx);
+			tot_enh_size_mult += gp_size_mult[pidx];
+		}
+	}
+
+	if (part_attrs && ! (mmc->part_support & ENHNCD_SUPPORT)) {
+		printf("Card does not support enhanced attribute\n");
+		return -EMEDIUMTYPE;
+	}
+
+	err = mmc_send_ext_csd(mmc, ext_csd);
+	if (err)
+		return err;
+
+	max_enh_size_mult =
+		(ext_csd[EXT_CSD_MAX_ENH_SIZE_MULT+2] << 16) +
+		(ext_csd[EXT_CSD_MAX_ENH_SIZE_MULT+1] << 8) +
+		ext_csd[EXT_CSD_MAX_ENH_SIZE_MULT];
+	if (tot_enh_size_mult > max_enh_size_mult) {
+		printf("Total enhanced size exceeds maximum (%u > %u)\n",
+		       tot_enh_size_mult, max_enh_size_mult);
+		return -EMEDIUMTYPE;
+	}
+
+	if (ext_csd[EXT_CSD_PARTITION_SETTING] &
+	    EXT_CSD_PARTITION_SETTING_COMPLETED) {
+		printf("Card already partitioned\n");
+		return -EPERM;
+	}
+
+	if (mode == MMC_HWPART_CONF_CHECK)
+		return 0;
+
+	/* Partitioning requires high-capacity size definitions */
+	if (!(ext_csd[EXT_CSD_ERASE_GROUP_DEF] & 0x01)) {
+		err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL,
+				 EXT_CSD_ERASE_GROUP_DEF, 1);
+
+		if (err)
+			return err;
+
+		ext_csd[EXT_CSD_ERASE_GROUP_DEF] = 1;
+
+		/* update erase group size to be high-capacity */
+		mmc->erase_grp_size =
+			ext_csd[EXT_CSD_HC_ERASE_GRP_SIZE] * 1024;
+
+	}
+
+	/* all OK, write the configuration */
+	for (i = 0; i < 4; i++) {
+		err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL,
+				 EXT_CSD_ENH_START_ADDR+i,
+				 (enh_start_addr >> (i*8)) & 0xFF);
+		if (err)
+			return err;
+	}
+	for (i = 0; i < 3; i++) {
+		err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL,
+				 EXT_CSD_ENH_SIZE_MULT+i,
+				 (enh_size_mult >> (i*8)) & 0xFF);
+		if (err)
+			return err;
+	}
+	for (pidx = 0; pidx < 4; pidx++) {
+		for (i = 0; i < 3; i++) {
+			err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL,
+					 EXT_CSD_GP_SIZE_MULT+pidx*3+i,
+					 (gp_size_mult[pidx] >> (i*8)) & 0xFF);
+			if (err)
+				return err;
+		}
+	}
+	err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL,
+			 EXT_CSD_PARTITIONS_ATTRIBUTE, part_attrs);
+	if (err)
+		return err;
+
+	if (mode == MMC_HWPART_CONF_SET)
+		return 0;
+
+	/* Setting PART_SETTING_COMPLETED confirms the partition
+	 * configuration but it only becomes effective after power
+	 * cycle, so we do not adjust the partition related settings
+	 * in the mmc struct. */
+
+	err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL,
+			 EXT_CSD_PARTITION_SETTING,
+			 EXT_CSD_PARTITION_SETTING_COMPLETED);
+	if (err)
+		return err;
+
+	return 0;
+}
+
 int mmc_getcd(struct mmc *mmc)
 {
 	int cd;