mtd: nand: sunxi: improve ->cmd_ctrl() function

Try to pack address and command cycles into a single NAND controller
command to avoid polling the status register for each single change
on the NAND bus.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/nand/sunxi_nand.c

@@ -238,6 +238,10 @@ struct sunxi_nand_chip {
 	u32 timing_cfg;
 	u32 timing_ctl;
 	int selected;
+	int addr_cycles;
+	u32 addr[2];
+	int cmd_cycles;
+	u8 cmd[2];
 	int nsels;
 	struct sunxi_nand_chip_sel sels[0];
 };
@@ -525,17 +529,49 @@ static void sunxi_nfc_cmd_ctrl(struct mtd_info *mtd, int dat,
 		writel(tmp, nfc->regs + NFC_REG_CTL);
 	}
 
-	if (dat == NAND_CMD_NONE)
-		return;
+	if (dat == NAND_CMD_NONE && (ctrl & NAND_NCE) &&
+	    !(ctrl & (NAND_CLE | NAND_ALE))) {
+		u32 cmd = 0;
 
-	if (ctrl & NAND_CLE) {
-		writel(NFC_SEND_CMD1 | dat, nfc->regs + NFC_REG_CMD);
-	} else {
-		writel(dat, nfc->regs + NFC_REG_ADDR_LOW);
-		writel(NFC_SEND_ADR, nfc->regs + NFC_REG_CMD);
+		if (!sunxi_nand->addr_cycles && !sunxi_nand->cmd_cycles)
+			return;
+
+		if (sunxi_nand->cmd_cycles--)
+			cmd |= NFC_SEND_CMD1 | sunxi_nand->cmd[0];
+
+		if (sunxi_nand->cmd_cycles--) {
+			cmd |= NFC_SEND_CMD2;
+			writel(sunxi_nand->cmd[1],
+			       nfc->regs + NFC_REG_RCMD_SET);
+		}
+
+		sunxi_nand->cmd_cycles = 0;
+
+		if (sunxi_nand->addr_cycles) {
+			cmd |= NFC_SEND_ADR |
+			       NFC_ADR_NUM(sunxi_nand->addr_cycles);
+			writel(sunxi_nand->addr[0],
+			       nfc->regs + NFC_REG_ADDR_LOW);
+		}
+
+		if (sunxi_nand->addr_cycles > 4)
+			writel(sunxi_nand->addr[1],
+			       nfc->regs + NFC_REG_ADDR_HIGH);
+
+		writel(cmd, nfc->regs + NFC_REG_CMD);
+		sunxi_nand->addr[0] = 0;
+		sunxi_nand->addr[1] = 0;
+		sunxi_nand->addr_cycles = 0;
+		sunxi_nfc_wait_int(nfc, NFC_CMD_INT_FLAG, 0);
 	}
 
-	sunxi_nfc_wait_int(nfc, NFC_CMD_INT_FLAG, 0);
+	if (ctrl & NAND_CLE) {
+		sunxi_nand->cmd[sunxi_nand->cmd_cycles++] = dat;
+	} else if (ctrl & NAND_ALE) {
+		sunxi_nand->addr[sunxi_nand->addr_cycles / 4] |=
+				dat << ((sunxi_nand->addr_cycles % 4) * 8);
+		sunxi_nand->addr_cycles++;
+	}
 }
 
 /* These seed values have been extracted from Allwinner's BSP */