mtd: cqspi: Simplify indirect write code

The indirect write code is buggy pile of nastiness which fails horribly
when the system runs fast enough to saturate the controller. The failure
results in some pages (256B) not being written to the flash. This can be
observed on systems which run with Dcache enabled and L2 cache enabled,
like the Altera SoCFPGA.

This patch replaces the whole unmaintainable indirect write implementation
with the one from upcoming Linux CQSPI driver, which went through multiple
rounds of thorough review and testing. While this makes the patch look
terrifying and violates all best-practices of software development, all
the patch does is it plucks out duplicate ad-hoc code distributed across
the driver and replaces it with more compact code doing exactly the same
thing.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Anatolij Gustschin <agust@denx.de>
Cc: Chin Liang See <clsee@altera.com>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Cc: Jagan Teki <jteki@openedev.com>
Cc: Pavel Machek <pavel@denx.de>
Cc: Stefan Roese <sr@denx.de>
Cc: Vignesh R <vigneshr@ti.com>

1 files changed, 30 insertions, 96 deletions

diff --git a/drivers/spi/cadence_qspi_apb.c b/drivers/spi/cadence_qspi_apb.c
index 7786dd65f5..5e84144940 100644
--- a/drivers/spi/cadence_qspi_apb.c
+++ b/drivers/spi/cadence_qspi_apb.c
@@ -28,6 +28,7 @@
 #include <common.h>
 #include <asm/io.h>
 #include <asm/errno.h>
+#include <wait_bit.h>
 #include "cadence_qspi.h"
 
 #define CQSPI_REG_POLL_US			(1) /* 1us */
@@ -214,32 +215,6 @@ static void cadence_qspi_apb_read_fifo_data(void *dest,
 	return;
 }
 
-static void cadence_qspi_apb_write_fifo_data(const void *dest_ahb_addr,
-	const void *src, unsigned int bytes)
-{
-	unsigned int temp = 0;
-	int i;
-	int remaining = bytes;
-	unsigned int *dest_ptr = (unsigned int *)dest_ahb_addr;
-	unsigned int *src_ptr = (unsigned int *)src;
-
-	while (remaining >= CQSPI_FIFO_WIDTH) {
-		for (i = CQSPI_FIFO_WIDTH/sizeof(src_ptr) - 1; i >= 0; i--)
-			writel(*(src_ptr+i), dest_ptr+i);
-		src_ptr += CQSPI_FIFO_WIDTH/sizeof(src_ptr);
-		remaining -= CQSPI_FIFO_WIDTH;
-	}
-	if (remaining) {
-		/* dangling bytes */
-		i = remaining/sizeof(dest_ptr);
-		memcpy(&temp, src_ptr+i, remaining % sizeof(dest_ptr));
-		writel(temp, dest_ptr+i);
-		for (--i; i >= 0; i--)
-			writel(*(src_ptr+i), dest_ptr+i);
-	}
-	return;
-}
-
 /* Read from SRAM FIFO with polling SRAM fill level. */
 static int qspi_read_sram_fifo_poll(const void *reg_base, void *dest_addr,
 			const void *src_addr,  unsigned int num_bytes)
@@ -276,44 +251,6 @@ static int qspi_read_sram_fifo_poll(const void *reg_base, void *dest_addr,
 	return 0;
 }
 
-/* Write to SRAM FIFO with polling SRAM fill level. */
-static int qpsi_write_sram_fifo_push(struct cadence_spi_platdata *plat,
-				const void *src_addr, unsigned int num_bytes)
-{
-	const void *reg_base = plat->regbase;
-	void *dest_addr = plat->ahbbase;
-	unsigned int retry = CQSPI_REG_RETRY;
-	unsigned int sram_level;
-	unsigned int wr_bytes;
-	unsigned char *src = (unsigned char *)src_addr;
-	int remaining = num_bytes;
-	unsigned int page_size = plat->page_size;
-	unsigned int sram_threshold_words = CQSPI_REG_SRAM_THRESHOLD_WORDS;
-
-	while (remaining > 0) {
-		retry = CQSPI_REG_RETRY;
-		while (retry--) {
-			sram_level = CQSPI_GET_WR_SRAM_LEVEL(reg_base);
-			if (sram_level <= sram_threshold_words)
-				break;
-		}
-		if (!retry) {
-			printf("QSPI: SRAM fill level (0x%08x) not hit lower expected level (0x%08x)",
-			       sram_level, sram_threshold_words);
-			return -1;
-		}
-		/* Write a page or remaining bytes. */
-		wr_bytes = (remaining > page_size) ?
-					page_size : remaining;
-
-		cadence_qspi_apb_write_fifo_data(dest_addr, src, wr_bytes);
-		src += wr_bytes;
-		remaining -= wr_bytes;
-	}
-
-	return 0;
-}
-
 void cadence_qspi_apb_controller_enable(void *reg_base)
 {
 	unsigned int reg;
@@ -810,48 +747,45 @@ int cadence_qspi_apb_indirect_write_setup(struct cadence_spi_platdata *plat,
 }
 
 int cadence_qspi_apb_indirect_write_execute(struct cadence_spi_platdata *plat,
-	unsigned int txlen, const u8 *txbuf)
+	unsigned int n_tx, const u8 *txbuf)
 {
-	unsigned int reg = 0;
-	unsigned int retry;
+	unsigned int page_size = plat->page_size;
+	unsigned int remaining = n_tx;
+	unsigned int write_bytes;
+	int ret;
 
 	/* Configure the indirect read transfer bytes */
-	writel(txlen, plat->regbase + CQSPI_REG_INDIRECTWRBYTES);
+	writel(n_tx, plat->regbase + CQSPI_REG_INDIRECTWRBYTES);
 
 	/* Start the indirect write transfer */
 	writel(CQSPI_REG_INDIRECTWR_START_MASK,
 	       plat->regbase + CQSPI_REG_INDIRECTWR);
 
-	if (qpsi_write_sram_fifo_push(plat, (const void *)txbuf, txlen))
-		goto failwr;
-
-	/* Wait until last write is completed (FIFO empty) */
-	retry = CQSPI_REG_RETRY;
-	while (retry--) {
-		reg = CQSPI_GET_WR_SRAM_LEVEL(plat->regbase);
-		if (reg == 0)
-			break;
-
-		udelay(1);
-	}
-
-	if (reg != 0) {
-		printf("QSPI: timeout for indirect write\n");
-		goto failwr;
-	}
+	while (remaining > 0) {
+		write_bytes = remaining > page_size ? page_size : remaining;
+		/* Handle non-4-byte aligned access to avoid data abort. */
+		if (((uintptr_t)txbuf % 4) || (write_bytes % 4))
+			writesb(plat->ahbbase, txbuf, write_bytes);
+		else
+			writesl(plat->ahbbase, txbuf, write_bytes >> 2);
+
+		ret = wait_for_bit("QSPI", plat->regbase + CQSPI_REG_SDRAMLEVEL,
+				   CQSPI_REG_SDRAMLEVEL_WR_MASK <<
+				   CQSPI_REG_SDRAMLEVEL_WR_LSB, 0, 10, 0);
+		if (ret) {
+			printf("Indirect write timed out (%i)\n", ret);
+			goto failwr;
+		}
 
-	/* Check flash indirect controller status */
-	retry = CQSPI_REG_RETRY;
-	while (retry--) {
-		reg = readl(plat->regbase + CQSPI_REG_INDIRECTWR);
-		if (reg & CQSPI_REG_INDIRECTWR_DONE_MASK)
-			break;
-		udelay(1);
+		txbuf += write_bytes;
+		remaining -= write_bytes;
 	}
 
-	if (!(reg & CQSPI_REG_INDIRECTWR_DONE_MASK)) {
-		printf("QSPI: indirect completion status error with reg 0x%08x\n",
-		       reg);
+	/* Check indirect done status */
+	ret = wait_for_bit("QSPI", plat->regbase + CQSPI_REG_INDIRECTWR,
+			   CQSPI_REG_INDIRECTWR_DONE_MASK, 1, 10, 0);
+	if (ret) {
+		printf("Indirect write completion error (%i)\n", ret);
 		goto failwr;
 	}
 
@@ -864,7 +798,7 @@ failwr:
 	/* Cancel the indirect write */
 	writel(CQSPI_REG_INDIRECTWR_CANCEL_MASK,
 	       plat->regbase + CQSPI_REG_INDIRECTWR);
-	return -1;
+	return ret;
 }
 
 void cadence_qspi_apb_enter_xip(void *reg_base, char xip_dummy)