spi: cadence-quadspi: Set dummy cycles from STIG commands

If a command does not have an address phase it goes via the STIG path.
The dummy cycles are not initialized for the STIG commands. As a result,
STIG commands with dummy cycles will not work.

Initialize the dummy cycle field before issuing the STIG command to make
sure it is sent correctly. Move the code to calculate dummy cycle value
to a separate function so it is not repeated twice. DTR support will add
some more logic here to it is worth it to extract it out in a function.

Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
Link: https://lore.kernel.org/r/20201222184425.7028-4-p.yadav@ti.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-cadence-quadspi.c

@@ -188,6 +188,7 @@ struct cqspi_driver_platdata {
 #define CQSPI_REG_CMDCTRL			0x90
 #define CQSPI_REG_CMDCTRL_EXECUTE_MASK		BIT(0)
 #define CQSPI_REG_CMDCTRL_INPROGRESS_MASK	BIT(1)
+#define CQSPI_REG_CMDCTRL_DUMMY_LSB		7
 #define CQSPI_REG_CMDCTRL_WR_BYTES_LSB		12
 #define CQSPI_REG_CMDCTRL_WR_EN_LSB		15
 #define CQSPI_REG_CMDCTRL_ADD_BYTES_LSB		16
@@ -198,6 +199,7 @@ struct cqspi_driver_platdata {
 #define CQSPI_REG_CMDCTRL_WR_BYTES_MASK		0x7
 #define CQSPI_REG_CMDCTRL_ADD_BYTES_MASK	0x3
 #define CQSPI_REG_CMDCTRL_RD_BYTES_MASK		0x7
+#define CQSPI_REG_CMDCTRL_DUMMY_MASK		0x1F
 
 #define CQSPI_REG_INDIRECTWR			0x70
 #define CQSPI_REG_INDIRECTWR_START_MASK		BIT(0)
@@ -288,6 +290,15 @@ static unsigned int cqspi_calc_rdreg(struct cqspi_flash_pdata *f_pdata)
 	return rdreg;
 }
 
+static unsigned int cqspi_calc_dummy(const struct spi_mem_op *op)
+{
+	unsigned int dummy_clk;
+
+	dummy_clk = op->dummy.nbytes * 8;
+
+	return dummy_clk;
+}
+
 static int cqspi_wait_idle(struct cqspi_st *cqspi)
 {
 	const unsigned int poll_idle_retry = 3;
@@ -355,6 +366,7 @@ static int cqspi_command_read(struct cqspi_flash_pdata *f_pdata,
 	size_t n_rx = op->data.nbytes;
 	unsigned int rdreg;
 	unsigned int reg;
+	unsigned int dummy_clk;
 	size_t read_len;
 	int status;
 
@@ -370,6 +382,14 @@ static int cqspi_command_read(struct cqspi_flash_pdata *f_pdata,
 	rdreg = cqspi_calc_rdreg(f_pdata);
 	writel(rdreg, reg_base + CQSPI_REG_RD_INSTR);
 
+	dummy_clk = cqspi_calc_dummy(op);
+	if (dummy_clk > CQSPI_DUMMY_CLKS_MAX)
+		return -EOPNOTSUPP;
+
+	if (dummy_clk)
+		reg |= (dummy_clk & CQSPI_REG_CMDCTRL_DUMMY_MASK)
+		     << CQSPI_REG_CMDCTRL_DUMMY_LSB;
+
 	reg |= (0x1 << CQSPI_REG_CMDCTRL_RD_EN_LSB);
 
 	/* 0 means 1 byte. */
@@ -459,7 +479,8 @@ static int cqspi_read_setup(struct cqspi_flash_pdata *f_pdata,
 	reg |= cqspi_calc_rdreg(f_pdata);
 
 	/* Setup dummy clock cycles */
-	dummy_clk = op->dummy.nbytes * 8;
+	dummy_clk = cqspi_calc_dummy(op);
+
 	if (dummy_clk > CQSPI_DUMMY_CLKS_MAX)
 		return -EOPNOTSUPP;