mmc: Tinification of the mmc code

Add new configuration option CONFIG_MMC_TINY which strips away all
memory allocation within the MMC code and code for handling multiple
cards. This allows extremely space-constrained SPL code use the MMC
framework.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Tom Rini <trini@konsulko.com>
Cc: Jaehoon Chung <jh80.chung@samsung.com>

common/spl/spl_mmc.c

@@ -306,7 +306,11 @@ static int spl_mmc_load_image(struct spl_image_info *spl_image,
 			if (part == 7)
 				part = 0;
 
-			err = blk_dselect_hwpart(mmc_get_blk_desc(mmc), part);
+			if (CONFIG_IS_ENABLED(MMC_TINY))
+				err = mmc_switch_part(mmc, part);
+			else
+				err = blk_dselect_hwpart(mmc_get_blk_desc(mmc), part);
+
 			if (err) {
 #ifdef CONFIG_SPL_LIBCOMMON_SUPPORT
 				puts("spl: mmc partition switch failed\n");

drivers/mmc/Kconfig

@@ -26,6 +26,21 @@ config DM_MMC_OPS
 	  option will be removed as soon as all DM_MMC drivers use it, as it
 	  will the only supported behaviour.
 
+config SPL_MMC_TINY
+	bool "Tiny MMC framework in SPL"
+	help
+	  Enable MMC framework tinification support. This option is useful if
+	  if your SPL is extremely size constrained. Heed the warning, enable
+	  this option if and only if you know exactly what you are doing, if
+	  you are reading this help text, you most likely have no idea :-)
+
+	  The MMC framework is reduced to bare minimum to be useful. No malloc
+	  support is needed for the MMC framework operation with this option
+	  enabled. The framework supports exactly one MMC device and exactly
+	  one MMC driver. The MMC driver can be adjusted to avoid any malloc
+	  operations too, which can remove the need for malloc support in SPL
+	  and thus further reduce footprint.
+
 config MSM_SDHCI
 	bool "Qualcomm SDHCI controller"
 	depends on DM_MMC && BLK && DM_MMC_OPS

drivers/mmc/mmc.c

@@ -30,6 +30,29 @@ static const unsigned int sd_au_size[] = {
 	SZ_16M / 512,	(SZ_16M + SZ_8M) / 512,	SZ_32M / 512,	SZ_64M / 512,
 };
 
+#if CONFIG_IS_ENABLED(MMC_TINY)
+static struct mmc mmc_static;
+struct mmc *find_mmc_device(int dev_num)
+{
+	return &mmc_static;
+}
+
+void mmc_do_preinit(void)
+{
+	struct mmc *m = &mmc_static;
+#ifdef CONFIG_FSL_ESDHC_ADAPTER_IDENT
+	mmc_set_preinit(m, 1);
+#endif
+	if (m->preinit)
+		mmc_start_init(m);
+}
+
+struct blk_desc *mmc_get_blk_desc(struct mmc *mmc)
+{
+	return &mmc->block_dev;
+}
+#endif
+
 #ifndef CONFIG_DM_MMC_OPS
 __weak int board_mmc_getwp(struct mmc *mmc)
 {
@@ -259,7 +282,11 @@ ulong mmc_bread(struct blk_desc *block_dev, lbaint_t start, lbaint_t blkcnt,
 	if (!mmc)
 		return 0;
 
-	err = blk_dselect_hwpart(block_dev, block_dev->hwpart);
+	if (CONFIG_IS_ENABLED(MMC_TINY))
+		err = mmc_switch_part(mmc, block_dev->hwpart);
+	else
+		err = blk_dselect_hwpart(block_dev, block_dev->hwpart);
+
 	if (err < 0)
 		return 0;
 
@@ -1804,8 +1831,10 @@ int mmc_initialize(bd_t *bis)
 	initialized = 1;
 
 #ifndef CONFIG_BLK
+#if !CONFIG_IS_ENABLED(MMC_TINY)
 	mmc_list_init();
 #endif
+#endif
 	ret = mmc_probe(bis);
 	if (ret)
 		return ret;

drivers/mmc/mmc_legacy.c

@@ -13,6 +13,7 @@
 static struct list_head mmc_devices;
 static int cur_dev_num = -1;
 
+#if !CONFIG_IS_ENABLED(MMC_TINY)
 struct mmc *find_mmc_device(int dev_num)
 {
 	struct mmc *m;
@@ -62,6 +63,7 @@ void mmc_do_preinit(void)
 			mmc_start_init(m);
 	}
 }
+#endif
 
 void mmc_list_init(void)
 {
@@ -109,6 +111,35 @@ void print_mmc_devices(char separator)
 void print_mmc_devices(char separator) { }
 #endif
 
+#if CONFIG_IS_ENABLED(MMC_TINY)
+static struct mmc mmc_static = {
+	.dsr_imp		= 0,
+	.dsr			= 0xffffffff,
+	.block_dev = {
+		.if_type	= IF_TYPE_MMC,
+		.removable	= 1,
+		.devnum		= 0,
+		.block_read	= mmc_bread,
+		.block_write	= mmc_bwrite,
+		.block_erase	= mmc_berase,
+		.part_type	= 0,
+	},
+};
+
+struct mmc *mmc_create(const struct mmc_config *cfg, void *priv)
+{
+	struct mmc *mmc = &mmc_static;
+
+	mmc->cfg = cfg;
+	mmc->priv = priv;
+
+	return mmc;
+}
+
+void mmc_destroy(struct mmc *mmc)
+{
+}
+#else
 struct mmc *mmc_create(const struct mmc_config *cfg, void *priv)
 {
 	struct blk_desc *bdesc;
@@ -157,6 +188,7 @@ void mmc_destroy(struct mmc *mmc)
 	/* only freeing memory for now */
 	free(mmc);
 }
+#endif
 
 static int mmc_select_hwpartp(struct blk_desc *desc, int hwpart)
 {

include/mmc.h

@@ -515,6 +515,7 @@ void print_mmc_devices(char separator);
  * @return 0 if there is no MMC device, else the number of devices
  */
 int get_mmc_num(void);
+int mmc_switch_part(struct mmc *mmc, unsigned int part_num);
 int mmc_hwpart_config(struct mmc *mmc, const struct mmc_hwpart_conf *conf,
 		      enum mmc_hwpart_conf_mode mode);