spi: atmel-quadspi: Add verbose debug facilities to monitor register accesses

This feature should not be enabled in release but can be useful for
developers who need to monitor register accesses at some specific places.

Helped me identify a bug in u-boot, by comparing the register accesses
from the u-boot driver with the ones from its linux variant.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
[jagan: use 16 bit array with tmp variable]
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>

drivers/spi/atmel-quadspi.c

@@ -148,6 +148,7 @@ struct atmel_qspi {
 	void __iomem *mem;
 	resource_size_t mmap_size;
 	const struct atmel_qspi_caps *caps;
+	struct udevice *dev;
 	ulong bus_clk_rate;
 	u32 mr;
 };
@@ -169,6 +170,81 @@ static const struct atmel_qspi_mode atmel_qspi_modes[] = {
 	{ 4, 4, 4, QSPI_IFR_WIDTH_QUAD_CMD },
 };
 
+#ifdef VERBOSE_DEBUG
+static const char *atmel_qspi_reg_name(u32 offset, char *tmp, size_t sz)
+{
+	switch (offset) {
+	case QSPI_CR:
+		return "CR";
+	case QSPI_MR:
+		return "MR";
+	case QSPI_RD:
+		return "MR";
+	case QSPI_TD:
+		return "TD";
+	case QSPI_SR:
+		return "SR";
+	case QSPI_IER:
+		return "IER";
+	case QSPI_IDR:
+		return "IDR";
+	case QSPI_IMR:
+		return "IMR";
+	case QSPI_SCR:
+		return "SCR";
+	case QSPI_IAR:
+		return "IAR";
+	case QSPI_ICR:
+		return "ICR/WICR";
+	case QSPI_IFR:
+		return "IFR";
+	case QSPI_RICR:
+		return "RICR";
+	case QSPI_SMR:
+		return "SMR";
+	case QSPI_SKR:
+		return "SKR";
+	case QSPI_WPMR:
+		return "WPMR";
+	case QSPI_WPSR:
+		return "WPSR";
+	case QSPI_VERSION:
+		return "VERSION";
+	default:
+		snprintf(tmp, sz, "0x%02x", offset);
+		break;
+	}
+
+	return tmp;
+}
+#endif /* VERBOSE_DEBUG */
+
+static u32 atmel_qspi_read(struct atmel_qspi *aq, u32 offset)
+{
+	u32 value = readl(aq->regs + offset);
+
+#ifdef VERBOSE_DEBUG
+	char tmp[16];
+
+	dev_vdbg(aq->dev, "read 0x%08x from %s\n", value,
+		 atmel_qspi_reg_name(offset, tmp, sizeof(tmp)));
+#endif /* VERBOSE_DEBUG */
+
+	return value;
+}
+
+static void atmel_qspi_write(u32 value, struct atmel_qspi *aq, u32 offset)
+{
+#ifdef VERBOSE_DEBUG
+	char tmp[16];
+
+	dev_vdbg(aq->dev, "write 0x%08x into %s\n", value,
+		 atmel_qspi_reg_name(offset, tmp, sizeof(tmp)));
+#endif /* VERBOSE_DEBUG */
+
+	writel(value, aq->regs + offset);
+}
+
 static inline bool atmel_qspi_is_compatible(const struct spi_mem_op *op,
 					    const struct atmel_qspi_mode *mode)
 {
@@ -289,32 +365,32 @@ static int atmel_qspi_set_cfg(struct atmel_qspi *aq,
 	 * Serial Memory Mode (SMM).
 	 */
 	if (aq->mr != QSPI_MR_SMM) {
-		writel(QSPI_MR_SMM, aq->regs + QSPI_MR);
+		atmel_qspi_write(QSPI_MR_SMM, aq, QSPI_MR);
 		aq->mr = QSPI_MR_SMM;
 	}
 
 	/* Clear pending interrupts */
-	(void)readl(aq->regs + QSPI_SR);
+	(void)atmel_qspi_read(aq, QSPI_SR);
 
 	if (aq->caps->has_ricr) {
 		if (!op->addr.nbytes && op->data.dir == SPI_MEM_DATA_IN)
 			ifr |= QSPI_IFR_APBTFRTYP_READ;
 
 		/* Set QSPI Instruction Frame registers */
-		writel(iar, aq->regs + QSPI_IAR);
+		atmel_qspi_write(iar, aq, QSPI_IAR);
 		if (op->data.dir == SPI_MEM_DATA_IN)
-			writel(icr, aq->regs + QSPI_RICR);
+			atmel_qspi_write(icr, aq, QSPI_RICR);
 		else
-			writel(icr, aq->regs + QSPI_WICR);
+			atmel_qspi_write(icr, aq, QSPI_WICR);
-		writel(ifr, aq->regs + QSPI_IFR);
+		atmel_qspi_write(ifr, aq, QSPI_IFR);
 	} else {
 		if (op->data.dir == SPI_MEM_DATA_OUT)
 			ifr |= QSPI_IFR_SAMA5D2_WRITE_TRSFR;
 
 		/* Set QSPI Instruction Frame registers */
-		writel(iar, aq->regs + QSPI_IAR);
+		atmel_qspi_write(iar, aq, QSPI_IAR);
-		writel(icr, aq->regs + QSPI_ICR);
+		atmel_qspi_write(icr, aq, QSPI_ICR);
-		writel(ifr, aq->regs + QSPI_IFR);
+		atmel_qspi_write(ifr, aq, QSPI_IFR);
 	}
 
 	return 0;
@@ -342,7 +418,7 @@ static int atmel_qspi_exec_op(struct spi_slave *slave,
 	/* Skip to the final steps if there is no data */
 	if (op->data.nbytes) {
 		/* Dummy read of QSPI_IFR to synchronize APB and AHB accesses */
-		(void)readl(aq->regs + QSPI_IFR);
+		(void)atmel_qspi_read(aq, QSPI_IFR);
 
 		/* Send/Receive data */
 		if (op->data.dir == SPI_MEM_DATA_IN)
@@ -353,7 +429,7 @@ static int atmel_qspi_exec_op(struct spi_slave *slave,
 				    op->data.nbytes);
 
 		/* Release the chip-select */
-		writel(QSPI_CR_LASTXFER, aq->regs + QSPI_CR);
+		atmel_qspi_write(QSPI_CR_LASTXFER, aq, QSPI_CR);
 	}
 
 	/* Poll INSTruction End and Chip Select Rise flags. */
@@ -375,12 +451,12 @@ static int atmel_qspi_set_speed(struct udevice *bus, uint hz)
 	new_value = QSPI_SCR_SCBR(scbr);
 	mask = QSPI_SCR_SCBR_MASK;
 
-	scr = readl(aq->regs + QSPI_SCR);
+	scr = atmel_qspi_read(aq, QSPI_SCR);
 	if ((scr & mask) == new_value)
 		return 0;
 
 	scr = (scr & ~mask) | new_value;
-	writel(scr, aq->regs + QSPI_SCR);
+	atmel_qspi_write(scr, aq, QSPI_SCR);
 
 	return 0;
 }
@@ -397,12 +473,12 @@ static int atmel_qspi_set_mode(struct udevice *bus, uint mode)
 
 	mask = QSPI_SCR_CPOL | QSPI_SCR_CPHA;
 
-	scr = readl(aq->regs + QSPI_SCR);
+	scr = atmel_qspi_read(aq, QSPI_SCR);
 	if ((scr & mask) == new_value)
 		return 0;
 
 	scr = (scr & ~mask) | new_value;
-	writel(scr, aq->regs + QSPI_SCR);
+	atmel_qspi_write(scr, aq, QSPI_SCR);
 
 	return 0;
 }
@@ -455,14 +531,14 @@ free_pclk:
 static void atmel_qspi_init(struct atmel_qspi *aq)
 {
 	/* Reset the QSPI controller */
-	writel(QSPI_CR_SWRST, aq->regs + QSPI_CR);
+	atmel_qspi_write(QSPI_CR_SWRST, aq, QSPI_CR);
 
 	/* Set the QSPI controller by default in Serial Memory Mode */
-	writel(QSPI_MR_SMM, aq->regs + QSPI_MR);
+	atmel_qspi_write(QSPI_MR_SMM, aq, QSPI_MR);
 	aq->mr = QSPI_MR_SMM;
 
 	/* Enable the QSPI controller */
-	writel(QSPI_CR_QSPIEN, aq->regs + QSPI_CR);
+	atmel_qspi_write(QSPI_CR_QSPIEN, aq, QSPI_CR);
 }
 
 static int atmel_qspi_probe(struct udevice *dev)
@@ -505,6 +581,8 @@ static int atmel_qspi_probe(struct udevice *dev)
 	if (ret)
 		return ret;
 
+	aq->dev = dev;
+
 	atmel_qspi_init(aq);
 
 	return 0;