[PATCH 7/7] spi: cadence: Force single modebyte

[Witold Sadowski <wsadowski@xxxxxxxxxxx>]

During dummy-cycles xSPI will switch GPIO into Hi-Z mode.
To prevent unforeseen consequences of that behaviour, force send
single modebyte(0x00).
Modebyte will be send only if number of dummy-cycles is not equal
to 0. Code must also reduce dummycycle byte count by one - as one byte
is send as modebyte.

Signed-off-by: Witold Sadowski <wsadowski@xxxxxxxxxxx>
Reviewed-by: Chandrakala Chavva <cchavva@xxxxxxxxxxx>
---
 drivers/spi/spi-cadence-xspi.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/spi/spi-cadence-xspi.c b/drivers/spi/spi-cadence-xspi.c
index c73faf6b0546..7d467169f62b 100644
--- a/drivers/spi/spi-cadence-xspi.c
+++ b/drivers/spi/spi-cadence-xspi.c
@@ -146,6 +146,9 @@
 #define CDNS_XSPI_STIG_DONE_FLAG		BIT(0)
 #define CDNS_XSPI_TRD_STATUS			0x0104
 
+#define MODE_NO_OF_BYTES			GENMASK(25, 24)
+#define MODEBYTES_COUNT			1
+
 /* Helper macros for filling command registers */
 #define CDNS_XSPI_CMD_FLD_P1_INSTR_CMD_1(op, data_phase) ( \
 	FIELD_PREP(CDNS_XSPI_CMD_INSTR_TYPE, (data_phase) ? \
@@ -158,9 +161,10 @@
 	FIELD_PREP(CDNS_XSPI_CMD_P1_R2_ADDR3, ((op)->addr.val >> 24) & 0xFF) | \
 	FIELD_PREP(CDNS_XSPI_CMD_P1_R2_ADDR4, ((op)->addr.val >> 32) & 0xFF))
 
-#define CDNS_XSPI_CMD_FLD_P1_INSTR_CMD_3(op) ( \
+#define CDNS_XSPI_CMD_FLD_P1_INSTR_CMD_3(op, modebytes) ( \
 	FIELD_PREP(CDNS_XSPI_CMD_P1_R3_ADDR5, ((op)->addr.val >> 40) & 0xFF) | \
 	FIELD_PREP(CDNS_XSPI_CMD_P1_R3_CMD, (op)->cmd.opcode) | \
+	FIELD_PREP(MODE_NO_OF_BYTES, modebytes) | \
 	FIELD_PREP(CDNS_XSPI_CMD_P1_R3_NUM_ADDR_BYTES, (op)->addr.nbytes))
 
 #define CDNS_XSPI_CMD_FLD_P1_INSTR_CMD_4(op, chipsel) ( \
@@ -174,12 +178,12 @@
 #define CDNS_XSPI_CMD_FLD_DSEQ_CMD_2(op) \
 	FIELD_PREP(CDNS_XSPI_CMD_DSEQ_R2_DCNT_L, (op)->data.nbytes & 0xFFFF)
 
-#define CDNS_XSPI_CMD_FLD_DSEQ_CMD_3(op) ( \
+#define CDNS_XSPI_CMD_FLD_DSEQ_CMD_3(op, dummybytes) ( \
 	FIELD_PREP(CDNS_XSPI_CMD_DSEQ_R3_DCNT_H, \
 		((op)->data.nbytes >> 16) & 0xffff) | \
 	FIELD_PREP(CDNS_XSPI_CMD_DSEQ_R3_NUM_OF_DUMMY, \
 		  (op)->dummy.buswidth != 0 ? \
-		  (((op)->dummy.nbytes * 8) / (op)->dummy.buswidth) : \
+		  (((dummybytes) * 8) / (op)->dummy.buswidth) : \
 		  0))
 
 #define CDNS_XSPI_CMD_FLD_DSEQ_CMD_4(op, chipsel) ( \
@@ -607,6 +611,7 @@ static int cdns_xspi_send_stig_command(struct cdns_xspi_dev *cdns_xspi,
 	u32 cmd_regs[6];
 	u32 cmd_status;
 	int ret;
+	int dummybytes = op->dummy.nbytes;
 
 	ret = cdns_xspi_wait_for_controller_idle(cdns_xspi);
 	if (ret < 0)
@@ -621,7 +626,12 @@ static int cdns_xspi_send_stig_command(struct cdns_xspi_dev *cdns_xspi,
 	memset(cmd_regs, 0, sizeof(cmd_regs));
 	cmd_regs[1] = CDNS_XSPI_CMD_FLD_P1_INSTR_CMD_1(op, data_phase);
 	cmd_regs[2] = CDNS_XSPI_CMD_FLD_P1_INSTR_CMD_2(op);
-	cmd_regs[3] = CDNS_XSPI_CMD_FLD_P1_INSTR_CMD_3(op);
+	if (dummybytes != 0) {
+		cmd_regs[3] = CDNS_XSPI_CMD_FLD_P1_INSTR_CMD_3(op, 1);
+		dummybytes--;
+	} else {
+		cmd_regs[3] = CDNS_XSPI_CMD_FLD_P1_INSTR_CMD_3(op, 0);
+	}
 	cmd_regs[4] = CDNS_XSPI_CMD_FLD_P1_INSTR_CMD_4(op,
 						       cdns_xspi->cur_cs);
 
@@ -631,7 +641,7 @@ static int cdns_xspi_send_stig_command(struct cdns_xspi_dev *cdns_xspi,
 		cmd_regs[0] = CDNS_XSPI_STIG_DONE_FLAG;
 		cmd_regs[1] = CDNS_XSPI_CMD_FLD_DSEQ_CMD_1(op);
 		cmd_regs[2] = CDNS_XSPI_CMD_FLD_DSEQ_CMD_2(op);
-		cmd_regs[3] = CDNS_XSPI_CMD_FLD_DSEQ_CMD_3(op);
+		cmd_regs[3] = CDNS_XSPI_CMD_FLD_DSEQ_CMD_3(op, dummybytes);
 		cmd_regs[4] = CDNS_XSPI_CMD_FLD_DSEQ_CMD_4(op,
 							   cdns_xspi->cur_cs);
 
-- 
2.17.1