[PATCH 7/7] spi: cadence-quadspi: Add DTR support

[Pratyush Yadav <p.yadav@xxxxxx>]

Double Transfer Rate (DTR) mode transfers data twice per clock cycle.
Add support for parsing DTR ops and set up the registers to allow it.

Most SPI NOR flashes expect 2 byte commands. Parse the 2-byte opcode
from SPI MEM and set it up in the CQSPI_REG_OP_EXT_LOWER register.

Increment the delay needed before issuing indirect writes because larger
delay is needed for DTR mode. With the current delay some writes end up
missing.

Signed-off-by: Pratyush Yadav <p.yadav@xxxxxx>
---
 drivers/spi/spi-cadence-quadspi.c | 281 +++++++++++++++++++++++++-----
 1 file changed, 242 insertions(+), 39 deletions(-)

diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
index 90040664e1b9..06a65e9a8a60 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -52,6 +52,7 @@ struct cqspi_flash_pdata {
 	u8		inst_width;
 	u8		addr_width;
 	u8		data_width;
+	bool		dtr;
 	u8		cs;
 };
 
@@ -111,6 +112,8 @@ struct cqspi_driver_platdata {
 #define CQSPI_REG_CONFIG_CHIPSELECT_LSB		10
 #define CQSPI_REG_CONFIG_DMA_MASK		BIT(15)
 #define CQSPI_REG_CONFIG_BAUD_LSB		19
+#define CQSPI_REG_CONFIG_DTR_PROTO		BIT(24)
+#define CQSPI_REG_CONFIG_DUAL_OPCODE		BIT(30)
 #define CQSPI_REG_CONFIG_IDLE_LSB		31
 #define CQSPI_REG_CONFIG_CHIPSELECT_MASK	0xF
 #define CQSPI_REG_CONFIG_BAUD_MASK		0xF
@@ -173,6 +176,9 @@ struct cqspi_driver_platdata {
 #define CQSPI_REG_SDRAMLEVEL_RD_MASK		0xFFFF
 #define CQSPI_REG_SDRAMLEVEL_WR_MASK		0xFFFF
 
+#define CQSPI_REG_WR_COMPLETION_CTRL		0x38
+#define CQSPI_REG_WR_DISABLE_AUTO_POLL		BIT(14)
+
 #define CQSPI_REG_IRQSTATUS			0x40
 #define CQSPI_REG_IRQMASK			0x44
 
@@ -216,6 +222,14 @@ struct cqspi_driver_platdata {
 #define CQSPI_REG_CMDWRITEDATALOWER		0xA8
 #define CQSPI_REG_CMDWRITEDATAUPPER		0xAC
 
+#define CQSPI_REG_POLLING_STATUS		0xB0
+#define CQSPI_REG_POLLING_STATUS_DUMMY_LSB	16
+
+#define CQSPI_REG_OP_EXT_LOWER			0xE0
+#define CQSPI_REG_OP_EXT_READ_LSB		24
+#define CQSPI_REG_OP_EXT_WRITE_LSB		16
+#define CQSPI_REG_OP_EXT_STIG_LSB		0
+
 /* Interrupt status bits */
 #define CQSPI_REG_IRQ_MODE_ERR			BIT(0)
 #define CQSPI_REG_IRQ_UNDERFLOW			BIT(1)
@@ -290,15 +304,80 @@ 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)
+static unsigned int cqspi_calc_dummy(const struct spi_mem_op *op, bool dtr)
 {
 	unsigned int dummy_clk;
 
 	dummy_clk = op->dummy.nbytes * (8 / op->dummy.buswidth);
+	if (dtr)
+		dummy_clk /= 2;
 
 	return dummy_clk;
 }
 
+static int cqspi_set_protocol(struct cqspi_flash_pdata *f_pdata,
+			      const struct spi_mem_op *op)
+{
+	f_pdata->inst_width = CQSPI_INST_TYPE_SINGLE;
+	f_pdata->addr_width = CQSPI_INST_TYPE_SINGLE;
+	f_pdata->data_width = CQSPI_INST_TYPE_SINGLE;
+	f_pdata->dtr = op->data.dtr && op->cmd.dtr && op->addr.dtr;
+
+	switch (op->data.buswidth) {
+	case 0:
+		break;
+	case 1:
+		f_pdata->data_width = CQSPI_INST_TYPE_SINGLE;
+		break;
+	case 2:
+		f_pdata->data_width = CQSPI_INST_TYPE_DUAL;
+		break;
+	case 4:
+		f_pdata->data_width = CQSPI_INST_TYPE_QUAD;
+		break;
+	case 8:
+		f_pdata->data_width = CQSPI_INST_TYPE_OCTAL;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* Right now we only support 8-8-8 DTR mode. */
+	if (f_pdata->dtr) {
+		switch (op->cmd.buswidth) {
+		case 0:
+			break;
+		case 8:
+			f_pdata->inst_width = CQSPI_INST_TYPE_OCTAL;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		switch (op->addr.buswidth) {
+		case 0:
+			break;
+		case 8:
+			f_pdata->addr_width = CQSPI_INST_TYPE_OCTAL;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		switch (op->data.buswidth) {
+		case 0:
+			break;
+		case 8:
+			f_pdata->data_width = CQSPI_INST_TYPE_OCTAL;
+			break;
+		default:
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
 static int cqspi_wait_idle(struct cqspi_st *cqspi)
 {
 	const unsigned int poll_idle_retry = 3;
@@ -356,13 +435,69 @@ static int cqspi_exec_flash_cmd(struct cqspi_st *cqspi, unsigned int reg)
 	return cqspi_wait_idle(cqspi);
 }
 
+static int cqspi_setup_opcode_ext(struct cqspi_flash_pdata *f_pdata,
+				  const struct spi_mem_op *op,
+				  unsigned int shift)
+{
+	struct cqspi_st *cqspi = f_pdata->cqspi;
+	void __iomem *reg_base = cqspi->iobase;
+	unsigned int reg;
+	u8 ext;
+
+	if (op->cmd.nbytes != 2)
+		return -EINVAL;
+
+	/* Opcode extension is the LSB. */
+	ext = op->cmd.opcode & 0xff;
+
+	reg = readl(reg_base + CQSPI_REG_OP_EXT_LOWER);
+	reg &= ~(0xff << shift);
+	reg |= ext << shift;
+	writel(reg, reg_base + CQSPI_REG_OP_EXT_LOWER);
+
+	return 0;
+}
+
+static int cqspi_enable_dtr(struct cqspi_flash_pdata *f_pdata,
+			    const struct spi_mem_op *op, unsigned int shift,
+			    bool enable)
+{
+	struct cqspi_st *cqspi = f_pdata->cqspi;
+	void __iomem *reg_base = cqspi->iobase;
+	unsigned int reg;
+	int ret;
+
+	reg = readl(reg_base + CQSPI_REG_CONFIG);
+
+	/*
+	 * We enable dual byte opcode here. The callers have to set up the
+	 * extension opcode based on which type of operation it is.
+	 */
+	if (enable) {
+		reg |= CQSPI_REG_CONFIG_DTR_PROTO;
+		reg |= CQSPI_REG_CONFIG_DUAL_OPCODE;
+
+		/* Set up command opcode extension. */
+		ret = cqspi_setup_opcode_ext(f_pdata, op, shift);
+		if (ret)
+			return ret;
+	} else {
+		reg &= ~CQSPI_REG_CONFIG_DTR_PROTO;
+		reg &= ~CQSPI_REG_CONFIG_DUAL_OPCODE;
+	}
+
+	writel(reg, reg_base + CQSPI_REG_CONFIG);
+
+	return cqspi_wait_idle(cqspi);
+}
+
 static int cqspi_command_read(struct cqspi_flash_pdata *f_pdata,
 			      const struct spi_mem_op *op)
 {
 	struct cqspi_st *cqspi = f_pdata->cqspi;
 	void __iomem *reg_base = cqspi->iobase;
 	u8 *rxbuf = op->data.buf.in;
-	u8 opcode = op->cmd.opcode;
+	u8 opcode;
 	size_t n_rx = op->data.nbytes;
 	unsigned int rdreg;
 	unsigned int reg;
@@ -370,6 +505,15 @@ static int cqspi_command_read(struct cqspi_flash_pdata *f_pdata,
 	size_t read_len;
 	int status;
 
+	status = cqspi_set_protocol(f_pdata, op);
+	if (status)
+		return status;
+
+	status = cqspi_enable_dtr(f_pdata, op, CQSPI_REG_OP_EXT_STIG_LSB,
+				  f_pdata->dtr);
+	if (status)
+		return status;
+
 	if (!n_rx || n_rx > CQSPI_STIG_DATA_LEN_MAX || !rxbuf) {
 		dev_err(&cqspi->pdev->dev,
 			"Invalid input argument, len %zu rxbuf 0x%p\n",
@@ -377,12 +521,17 @@ static int cqspi_command_read(struct cqspi_flash_pdata *f_pdata,
 		return -EINVAL;
 	}
 
+	if (f_pdata->dtr)
+		opcode = op->cmd.opcode >> 8;
+	else
+		opcode = op->cmd.opcode;
+
 	reg = opcode << CQSPI_REG_CMDCTRL_OPCODE_LSB;
 
 	rdreg = cqspi_calc_rdreg(f_pdata);
 	writel(rdreg, reg_base + CQSPI_REG_RD_INSTR);
 
-	dummy_clk = cqspi_calc_dummy(op);
+	dummy_clk = cqspi_calc_dummy(op, f_pdata->dtr);
 	if (dummy_clk > CQSPI_DUMMY_CLKS_MAX)
 		return -EOPNOTSUPP;
 
@@ -421,12 +570,22 @@ static int cqspi_command_write(struct cqspi_flash_pdata *f_pdata,
 {
 	struct cqspi_st *cqspi = f_pdata->cqspi;
 	void __iomem *reg_base = cqspi->iobase;
-	const u8 opcode = op->cmd.opcode;
+	u8 opcode;
 	const u8 *txbuf = op->data.buf.out;
 	size_t n_tx = op->data.nbytes;
 	unsigned int reg;
 	unsigned int data;
 	size_t write_len;
+	int ret;
+
+	ret = cqspi_set_protocol(f_pdata, op);
+	if (ret)
+		return ret;
+
+	ret = cqspi_enable_dtr(f_pdata, op, CQSPI_REG_OP_EXT_STIG_LSB,
+			       f_pdata->dtr);
+	if (ret)
+		return ret;
 
 	if (n_tx > CQSPI_STIG_DATA_LEN_MAX || (n_tx && !txbuf)) {
 		dev_err(&cqspi->pdev->dev,
@@ -435,6 +594,14 @@ static int cqspi_command_write(struct cqspi_flash_pdata *f_pdata,
 		return -EINVAL;
 	}
 
+	reg = cqspi_calc_rdreg(f_pdata);
+	writel(reg, reg_base + CQSPI_REG_RD_INSTR);
+
+	if (f_pdata->dtr)
+		opcode = op->cmd.opcode >> 8;
+	else
+		opcode = op->cmd.opcode;
+
 	reg = opcode << CQSPI_REG_CMDCTRL_OPCODE_LSB;
 
 	if (op->addr.nbytes) {
@@ -474,12 +641,24 @@ static int cqspi_read_setup(struct cqspi_flash_pdata *f_pdata,
 	void __iomem *reg_base = cqspi->iobase;
 	unsigned int dummy_clk = 0;
 	unsigned int reg;
+	int ret;
+	u8 opcode;
 
-	reg = op->cmd.opcode << CQSPI_REG_RD_INSTR_OPCODE_LSB;
+	ret = cqspi_enable_dtr(f_pdata, op, CQSPI_REG_OP_EXT_READ_LSB,
+			       f_pdata->dtr);
+	if (ret)
+		return ret;
+
+	if (f_pdata->dtr)
+		opcode = op->cmd.opcode >> 8;
+	else
+		opcode = op->cmd.opcode;
+
+	reg = opcode << CQSPI_REG_RD_INSTR_OPCODE_LSB;
 	reg |= cqspi_calc_rdreg(f_pdata);
 
 	/* Setup dummy clock cycles */
-	dummy_clk = cqspi_calc_dummy(op);
+	dummy_clk = cqspi_calc_dummy(op, f_pdata->dtr);
 
 	if (dummy_clk > CQSPI_DUMMY_CLKS_MAX)
 		return -EOPNOTSUPP;
@@ -594,15 +773,43 @@ static int cqspi_write_setup(struct cqspi_flash_pdata *f_pdata,
 			     const struct spi_mem_op *op)
 {
 	unsigned int reg;
+	int ret;
 	struct cqspi_st *cqspi = f_pdata->cqspi;
 	void __iomem *reg_base = cqspi->iobase;
+	u8 opcode;
+
+	ret = cqspi_enable_dtr(f_pdata, op, CQSPI_REG_OP_EXT_WRITE_LSB,
+			       f_pdata->dtr);
+	if (ret)
+		return ret;
+
+	if (f_pdata->dtr)
+		opcode = op->cmd.opcode >> 8;
+	else
+		opcode = op->cmd.opcode;
 
 	/* Set opcode. */
-	reg = op->cmd.opcode << CQSPI_REG_WR_INSTR_OPCODE_LSB;
+	reg = opcode << CQSPI_REG_WR_INSTR_OPCODE_LSB;
+	reg |= f_pdata->data_width << CQSPI_REG_WR_INSTR_TYPE_DATA_LSB;
+	reg |= f_pdata->addr_width << CQSPI_REG_WR_INSTR_TYPE_ADDR_LSB;
 	writel(reg, reg_base + CQSPI_REG_WR_INSTR);
 	reg = cqspi_calc_rdreg(f_pdata);
 	writel(reg, reg_base + CQSPI_REG_RD_INSTR);
 
+	if (f_pdata->dtr) {
+		/*
+		 * Some flashes like the cypress Semper flash expect a 4-byte
+		 * dummy address with the Read SR command in DTR mode, but this
+		 * controller does not support sending address with the Read SR
+		 * command. So, disable write completion polling on the
+		 * controller's side. spi-nor will take care of polling the
+		 * status register.
+		 */
+		reg = readl(reg_base + CQSPI_REG_WR_COMPLETION_CTRL);
+		reg |= CQSPI_REG_WR_DISABLE_AUTO_POLL;
+		writel(reg, reg_base + CQSPI_REG_WR_COMPLETION_CTRL);
+	}
+
 	reg = readl(reg_base + CQSPI_REG_SIZE);
 	reg &= ~CQSPI_REG_SIZE_ADDRESS_MASK;
 	reg |= (op->addr.nbytes - 1);
@@ -856,35 +1063,6 @@ static void cqspi_configure(struct cqspi_flash_pdata *f_pdata,
 		cqspi_controller_enable(cqspi, 1);
 }
 
-static int cqspi_set_protocol(struct cqspi_flash_pdata *f_pdata,
-			      const struct spi_mem_op *op)
-{
-	f_pdata->inst_width = CQSPI_INST_TYPE_SINGLE;
-	f_pdata->addr_width = CQSPI_INST_TYPE_SINGLE;
-	f_pdata->data_width = CQSPI_INST_TYPE_SINGLE;
-
-	if (op->data.dir == SPI_MEM_DATA_IN) {
-		switch (op->data.buswidth) {
-		case 1:
-			f_pdata->data_width = CQSPI_INST_TYPE_SINGLE;
-			break;
-		case 2:
-			f_pdata->data_width = CQSPI_INST_TYPE_DUAL;
-			break;
-		case 4:
-			f_pdata->data_width = CQSPI_INST_TYPE_QUAD;
-			break;
-		case 8:
-			f_pdata->data_width = CQSPI_INST_TYPE_OCTAL;
-			break;
-		default:
-			return -EINVAL;
-		}
-	}
-
-	return 0;
-}
-
 static ssize_t cqspi_write(struct cqspi_flash_pdata *f_pdata,
 			   const struct spi_mem_op *op)
 {
@@ -902,7 +1080,16 @@ static ssize_t cqspi_write(struct cqspi_flash_pdata *f_pdata,
 	if (ret)
 		return ret;
 
-	if (cqspi->use_direct_mode && ((to + len) <= cqspi->ahb_size)) {
+	/*
+	 * Some flashes like the Cypress Semper flash expect a dummy 4-byte
+	 * address (all 0s) with the read status register command in DTR mode.
+	 * But this controller does not support sending dummy address bytes to
+	 * the flash when it is polling the write completion register in DTR
+	 * mode. So, we can not use direct mode when in DTR mode for writing
+	 * data.
+	 */
+	if (!f_pdata->dtr && cqspi->use_direct_mode &&
+	    ((to + len) <= cqspi->ahb_size)) {
 		memcpy_toio(cqspi->ahb_base + to, buf, len);
 		return cqspi_wait_idle(cqspi);
 	}
@@ -1072,6 +1259,8 @@ static int cqspi_check_buswidth_req(struct spi_mem *mem, u8 buswidth, bool tx)
 static bool cqspi_supports_mem_op(struct spi_mem *mem,
 				  const struct spi_mem_op *op)
 {
+	bool all_true, all_false;
+
 	if (cqspi_check_buswidth_req(mem, op->cmd.buswidth, true))
 		return false;
 
@@ -1088,6 +1277,19 @@ static bool cqspi_supports_mem_op(struct spi_mem *mem,
 				     op->data.dir == SPI_MEM_DATA_OUT))
 		return false;
 
+	all_true = op->cmd.dtr && op->addr.dtr && op->dummy.dtr &&
+		   op->data.dtr;
+	all_false = !op->cmd.dtr && !op->addr.dtr && !op->dummy.dtr &&
+		    !op->data.dtr;
+
+	/* Mixed DTR modes not supported. */
+	if (!(all_true || all_false))
+		return false;
+
+	/* DTR mode opcodes should be 2 bytes. */
+	if (all_true && op->cmd.nbytes != 2)
+		return false;
+
 	return true;
 }
 
@@ -1365,10 +1567,10 @@ static int cqspi_probe(struct platform_device *pdev)
 	ddata  = of_device_get_match_data(dev);
 	if (ddata) {
 		if (ddata->quirks & CQSPI_NEEDS_WR_DELAY)
-			cqspi->wr_delay = 5 * DIV_ROUND_UP(NSEC_PER_SEC,
+			cqspi->wr_delay = 50 * DIV_ROUND_UP(NSEC_PER_SEC,
 						cqspi->master_ref_clk_hz);
 		if (ddata->hwcaps_mask & CQSPI_SUPPORTS_OCTAL)
-			master->mode_bits |= SPI_RX_OCTAL;
+			master->mode_bits |= SPI_RX_OCTAL | SPI_TX_OCTAL;
 		if (!(ddata->quirks & CQSPI_DISABLE_DAC_MODE))
 			cqspi->use_direct_mode = true;
 	}
@@ -1510,3 +1712,4 @@ MODULE_AUTHOR("Ley Foon Tan <lftan@xxxxxxxxxx>");
 MODULE_AUTHOR("Graham Moore <grmoore@xxxxxxxxxxxxxxxxxxxxx>");
 MODULE_AUTHOR("Vadivel Murugan R <vadivel.muruganx.ramuthevar@xxxxxxxxx>");
 MODULE_AUTHOR("Vignesh Raghavendra <vigneshr@xxxxxx>");
+MODULE_AUTHOR("Pratyush Yadav <p.yadav@xxxxxx>");
-- 
2.28.0