[PATCH v3] memory: renesas-rpc-if: Fix HF/OSPI data transfer in Manual mode

[Geert Uytterhoeven]

HyperFlash devices fail to probe:

    rpc-if-hyperflash rpc-if-hyperflash: probing of hyperbus device failed

In HyperFlash or Octal-SPI Flash mode, the Transfer Data Enable bits
(SPIDE) in the Manual Mode Enable Setting Register (SMENR) are derived
from half of the transfer size, cfr. the rpcif_bits_set() helper
function.  However, rpcif_reg_{read,write}() does not take the bus size
into account, and does not double all Manual Mode Data Register access
sizes when communicating with a HyperFlash or Octal-SPI Flash device.

Fix this, and avoid the back-and-forth conversion between transfer size
and Transfer Data Enable bits, by explicitly storing the transfer size
in struct rpcif, and using that value to determine access size in
rpcif_reg_{read,write}().

Enforce that the "high" Manual Mode Read/Write Data Registers
(SM[RW]DR1) are only used for 8-byte data accesses.
While at it, forbid writing to the Manual Mode Read Data Registers,
as they are read-only.

Fixes: fff53a551db50f5e ("memory: renesas-rpc-if: Correct QSPI data transfer in Manual mode")
Signed-off-by: Geert Uytterhoeven <geert+renesas at glider.be>
Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj at bp.renesas.com> [QSPI]
---
Lightly (read-only) tested on:
  - Salvator-XS, ULCB, Ebisu-4D, and Draak (with R-Car H3 ES1.1 and
    ES2.0, M3-W ES1.0, M3-N ES1.0, E3 ES1.0, and D3 ES1.0) with
    HyperFlash,
  - Falcon with R-Car V3U ES1.0 with QSPI.

v3:
  - Add Tested-by,
  - Update comments to match changed code,
  - Add explicit {read,write}l() for the 4/8 byte case, to increase
    readability,
  - Remove redundant break statements,
  - Tested HyperFlash on more boards and SoCs.

v2:
  - Use rpc->xfer_size instead of SPIDE register reads and
    rpc->bus_size.
      Note: Alternatively, rpcif_manual_xfer() could bypass regmap and
      use {read,write}[bwl]() directly, cfr. commit 0d37f69cacb33435
      ("memory: renesas-rpc-if: Correct QSPI data transfer in Manual
      mode") in the BSP.
  - HF dirmap reads are confirmed to work on R-Car M3-W,
  - Drop RFC.
---
 drivers/memory/renesas-rpc-if.c | 60 +++++++++++++++++++++++++--------
 include/memory/renesas-rpc-if.h |  1 +
 2 files changed, 47 insertions(+), 14 deletions(-)

diff --git a/drivers/memory/renesas-rpc-if.c b/drivers/memory/renesas-rpc-if.c
index e4cc64f560196d55..64582b54400da2ba 100644
--- a/drivers/memory/renesas-rpc-if.c
+++ b/drivers/memory/renesas-rpc-if.c
@@ -164,25 +164,39 @@ static const struct regmap_access_table rpcif_volatile_table = {
 
 
 /*
- * Custom accessor functions to ensure SMRDR0 and SMWDR0 are always accessed
- * with proper width. Requires SMENR_SPIDE to be correctly set before!
+ * Custom accessor functions to ensure SM[RW]DR[01] are always accessed with
+ * proper width.  Requires rpcif.xfer_size to be correctly set before!
  */
 static int rpcif_reg_read(void *context, unsigned int reg, unsigned int *val)
 {
 	struct rpcif *rpc = context;
 
-	if (reg == RPCIF_SMRDR0 || reg == RPCIF_SMWDR0) {
-		u32 spide = readl(rpc->base + RPCIF_SMENR) & RPCIF_SMENR_SPIDE(0xF);
-
-		if (spide == 0x8) {
+	switch (reg) {
+	case RPCIF_SMRDR0:
+	case RPCIF_SMWDR0:
+		switch (rpc->xfer_size) {
+		case 1:
 			*val = readb(rpc->base + reg);
 			return 0;
-		} else if (spide == 0xC) {
+
+		case 2:
 			*val = readw(rpc->base + reg);
 			return 0;
-		} else if (spide != 0xF) {
+
+		case 4:
+		case 8:
+			*val = readl(rpc->base + reg);
+			return 0;
+
+		default:
 			return -EILSEQ;
 		}
+
+	case RPCIF_SMRDR1:
+	case RPCIF_SMWDR1:
+		if (rpc->xfer_size != 8)
+			return -EILSEQ;
+		break;
 	}
 
 	*val = readl(rpc->base + reg);
@@ -193,18 +207,34 @@ static int rpcif_reg_write(void *context, unsigned int reg, unsigned int val)
 {
 	struct rpcif *rpc = context;
 
-	if (reg == RPCIF_SMRDR0 || reg == RPCIF_SMWDR0) {
-		u32 spide = readl(rpc->base + RPCIF_SMENR) & RPCIF_SMENR_SPIDE(0xF);
-
-		if (spide == 0x8) {
+	switch (reg) {
+	case RPCIF_SMWDR0:
+		switch (rpc->xfer_size) {
+		case 1:
 			writeb(val, rpc->base + reg);
 			return 0;
-		} else if (spide == 0xC) {
+
+		case 2:
 			writew(val, rpc->base + reg);
 			return 0;
-		} else if (spide != 0xF) {
+
+		case 4:
+		case 8:
+			writel(val, rpc->base + reg);
+			return 0;
+
+		default:
 			return -EILSEQ;
 		}
+
+	case RPCIF_SMWDR1:
+		if (rpc->xfer_size != 8)
+			return -EILSEQ;
+		break;
+
+	case RPCIF_SMRDR0:
+	case RPCIF_SMRDR1:
+		return -EPERM;
 	}
 
 	writel(val, rpc->base + reg);
@@ -469,6 +499,7 @@ int rpcif_manual_xfer(struct rpcif *rpc)
 
 			smenr |= RPCIF_SMENR_SPIDE(rpcif_bits_set(rpc, nbytes));
 			regmap_write(rpc->regmap, RPCIF_SMENR, smenr);
+			rpc->xfer_size = nbytes;
 
 			memcpy(data, rpc->buffer + pos, nbytes);
 			if (nbytes == 8) {
@@ -533,6 +564,7 @@ int rpcif_manual_xfer(struct rpcif *rpc)
 			regmap_write(rpc->regmap, RPCIF_SMENR, smenr);
 			regmap_write(rpc->regmap, RPCIF_SMCR,
 				     rpc->smcr | RPCIF_SMCR_SPIE);
+			rpc->xfer_size = nbytes;
 			ret = wait_msg_xfer_end(rpc);
 			if (ret)
 				goto err_out;
diff --git a/include/memory/renesas-rpc-if.h b/include/memory/renesas-rpc-if.h
index 7c93f5177532f187..9c0ad64b8d292d49 100644
--- a/include/memory/renesas-rpc-if.h
+++ b/include/memory/renesas-rpc-if.h
@@ -72,6 +72,7 @@ struct rpcif {
 	enum rpcif_type type;
 	enum rpcif_data_dir dir;
 	u8 bus_size;
+	u8 xfer_size;
 	void *buffer;
 	u32 xferlen;
 	u32 smcr;
-- 
2.25.1