[U-Boot] [PATCH 2/2] mmc: jz_mmc: Compile-out write support if disabled

[Ezequiel Garcia]

Do not build write support, unless it's enabled.

In the SPL case, this change will typically remove
precious bytes (as write support is most often
not needed in SPL).

This is important on this platform, where the maximum
SPL size is 14 KiB.

With gcc v7.3, this change saves 144 bytes producing:

size spl/u-boot-spl
   text	   data	    bss	    dec	    hex	filename
   9240	    752	    712	  10704	   29d0	spl/u-boot-spl

To make the code easier to compile-out and more
readable, a pair of read_data/write_data helpers are created.

Signed-off-by: Ezequiel Garcia <ezequiel at collabora.com>
---
 drivers/mmc/jz_mmc.c | 105 +++++++++++++++++++++++++------------------
 1 file changed, 61 insertions(+), 44 deletions(-)

diff --git a/drivers/mmc/jz_mmc.c b/drivers/mmc/jz_mmc.c
index 3132c3e191ac..cb2a7c3eb5e1 100644
--- a/drivers/mmc/jz_mmc.c
+++ b/drivers/mmc/jz_mmc.c
@@ -134,6 +134,60 @@ static int jz_mmc_clock_rate(void)
 	return 24000000;
 }
 
+#if CONFIG_IS_ENABLED(MMC_WRITE)
+static inline void jz_mmc_write_data(struct jz_mmc_priv *priv, struct mmc_data *data)
+{
+	int sz = DIV_ROUND_UP(data->blocks * data->blocksize, 4);
+	const void *buf = data->src;
+
+	while (sz--) {
+		u32 val = get_unaligned_le32(buf);
+
+		wait_for_bit_le32(priv->regs + MSC_IREG,
+				  MSC_IREG_TXFIFO_WR_REQ,
+				  true, 10000, false);
+		writel(val, priv->regs + MSC_TXFIFO);
+		buf += 4;
+	}
+}
+#else
+static void jz_mmc_write_data(struct jz_mmc_priv *priv, struct mmc_data *data)
+{}
+#endif
+
+static inline int jz_mmc_read_data(struct jz_mmc_priv *priv, struct mmc_data *data)
+{
+	int sz = data->blocks * data->blocksize;
+	void *buf = data->dest;
+	u32 stat, val;
+
+	do {
+		stat = readl(priv->regs + MSC_STAT);
+
+		if (stat & MSC_STAT_TIME_OUT_READ)
+			return -ETIMEDOUT;
+		if (stat & MSC_STAT_CRC_READ_ERROR)
+			return -EINVAL;
+		if (stat & MSC_STAT_DATA_FIFO_EMPTY) {
+			udelay(10);
+			continue;
+		}
+		do {
+			val = readl(priv->regs + MSC_RXFIFO);
+			if (sz == 1)
+				*(u8 *)buf = (u8)val;
+			else if (sz == 2)
+				put_unaligned_le16(val, buf);
+			else if (sz >= 4)
+				put_unaligned_le32(val, buf);
+			buf += 4;
+			sz -= 4;
+			stat = readl(priv->regs + MSC_STAT);
+		} while (!(stat & MSC_STAT_DATA_FIFO_EMPTY));
+	} while (!(stat & MSC_STAT_DATA_TRAN_DONE));
+	return 0;
+}
+
 static int jz_mmc_send_cmd(struct mmc *mmc, struct jz_mmc_priv *priv,
 			   struct mmc_cmd *cmd, struct mmc_data *data)
 {
@@ -249,51 +303,14 @@ static int jz_mmc_send_cmd(struct mmc *mmc, struct jz_mmc_priv *priv,
 			cmd->response[0] |= readw(priv->regs + MSC_RES) & 0xff;
 		}
 	}
-
-	if (data && (data->flags & MMC_DATA_WRITE)) {
-		/* write the data */
-		int sz = DIV_ROUND_UP(data->blocks * data->blocksize, 4);
-		const void *buf = data->src;
-
-		while (sz--) {
-			u32 val = get_unaligned_le32(buf);
-
-			wait_for_bit_le32(priv->regs + MSC_IREG,
-					  MSC_IREG_TXFIFO_WR_REQ,
-					  true, 10000, false);
-			writel(val, priv->regs + MSC_TXFIFO);
-			buf += 4;
+	if (data) {
+		if (data->flags & MMC_DATA_WRITE)
+			jz_mmc_write_data(priv, data);
+		else if (data->flags & MMC_DATA_READ) {
+			ret = jz_mmc_read_data(priv, data);
+			if (ret)
+				return ret;
 		}
-	} else if (data && (data->flags & MMC_DATA_READ)) {
-		/* read the data */
-		int sz = data->blocks * data->blocksize;
-		void *buf = data->dest;
-
-		do {
-			stat = readl(priv->regs + MSC_STAT);
-
-			if (stat & MSC_STAT_TIME_OUT_READ)
-				return -ETIMEDOUT;
-			if (stat & MSC_STAT_CRC_READ_ERROR)
-				return -EINVAL;
-			if (stat & MSC_STAT_DATA_FIFO_EMPTY) {
-				udelay(10);
-				continue;
-			}
-			do {
-				u32 val = readl(priv->regs + MSC_RXFIFO);
-
-				if (sz == 1)
-					*(u8 *)buf = (u8)val;
-				else if (sz == 2)
-					put_unaligned_le16(val, buf);
-				else if (sz >= 4)
-					put_unaligned_le32(val, buf);
-				buf += 4;
-				sz -= 4;
-				stat = readl(priv->regs + MSC_STAT);
-			} while (!(stat & MSC_STAT_DATA_FIFO_EMPTY));
-		} while (!(stat & MSC_STAT_DATA_TRAN_DONE));
 	}
 
 	return 0;
-- 
2.20.1