Miscellaneous fixes and clean-ups

Merge series from Santhosh Kumar K <s-k6@ti.com>:

This series introduces some small but important fixes and cleanups in
the Cadence QSPI Controller.

Tested on TI's AM62A SK and AM62P SK:
Logs: https://gist.github.com/santhosh21/0d25767b58d9a1d9624f2c502dd8f36b

Author: broonie

drivers/spi/spi-cadence-quadspi.c

@@ -335,7 +335,7 @@ static bool cqspi_is_idle(struct cqspi_st *cqspi)
 {
 	u32 reg = readl(cqspi->iobase + CQSPI_REG_CONFIG);
 
-	return reg & (1UL << CQSPI_REG_CONFIG_IDLE_LSB);
+	return reg & BIT(CQSPI_REG_CONFIG_IDLE_LSB);
 }
 
 static u32 cqspi_get_rd_sram_level(struct cqspi_st *cqspi)
@@ -571,15 +571,15 @@ static int cqspi_command_read(struct cqspi_flash_pdata *f_pdata,
 		reg |= (dummy_clk & CQSPI_REG_CMDCTRL_DUMMY_MASK)
 		     << CQSPI_REG_CMDCTRL_DUMMY_LSB;
 
-	reg |= (0x1 << CQSPI_REG_CMDCTRL_RD_EN_LSB);
+	reg |= BIT(CQSPI_REG_CMDCTRL_RD_EN_LSB);
 
 	/* 0 means 1 byte. */
 	reg |= (((n_rx - 1) & CQSPI_REG_CMDCTRL_RD_BYTES_MASK)
 		<< CQSPI_REG_CMDCTRL_RD_BYTES_LSB);
 
 	/* setup ADDR BIT field */
 	if (op->addr.nbytes) {
-		reg |= (0x1 << CQSPI_REG_CMDCTRL_ADDR_EN_LSB);
+		reg |= BIT(CQSPI_REG_CMDCTRL_ADDR_EN_LSB);
 		reg |= ((op->addr.nbytes - 1) &
 			CQSPI_REG_CMDCTRL_ADD_BYTES_MASK)
 			<< CQSPI_REG_CMDCTRL_ADD_BYTES_LSB;
@@ -646,7 +646,7 @@ static int cqspi_command_write(struct cqspi_flash_pdata *f_pdata,
 	reg = opcode << CQSPI_REG_CMDCTRL_OPCODE_LSB;
 
 	if (op->addr.nbytes) {
-		reg |= (0x1 << CQSPI_REG_CMDCTRL_ADDR_EN_LSB);
+		reg |= BIT(CQSPI_REG_CMDCTRL_ADDR_EN_LSB);
 		reg |= ((op->addr.nbytes - 1) &
 			CQSPI_REG_CMDCTRL_ADD_BYTES_MASK)
 			<< CQSPI_REG_CMDCTRL_ADD_BYTES_LSB;
@@ -655,7 +655,7 @@ static int cqspi_command_write(struct cqspi_flash_pdata *f_pdata,
 	}
 
 	if (n_tx) {
-		reg |= (0x1 << CQSPI_REG_CMDCTRL_WR_EN_LSB);
+		reg |= BIT(CQSPI_REG_CMDCTRL_WR_EN_LSB);
 		reg |= ((n_tx - 1) & CQSPI_REG_CMDCTRL_WR_BYTES_MASK)
 			<< CQSPI_REG_CMDCTRL_WR_BYTES_LSB;
 		data = 0;
@@ -719,6 +719,7 @@ static int cqspi_read_setup(struct cqspi_flash_pdata *f_pdata,
 	reg &= ~CQSPI_REG_SIZE_ADDRESS_MASK;
 	reg |= (op->addr.nbytes - 1);
 	writel(reg, reg_base + CQSPI_REG_SIZE);
+	readl(reg_base + CQSPI_REG_SIZE); /* Flush posted write. */
 	return 0;
 }
 
@@ -764,6 +765,7 @@ static int cqspi_indirect_read_execute(struct cqspi_flash_pdata *f_pdata,
 	reinit_completion(&cqspi->transfer_complete);
 	writel(CQSPI_REG_INDIRECTRD_START_MASK,
 	       reg_base + CQSPI_REG_INDIRECTRD);
+	readl(reg_base + CQSPI_REG_INDIRECTRD); /* Flush posted write. */
 
 	while (remaining > 0) {
 		if (use_irq &&
@@ -1062,6 +1064,7 @@ static int cqspi_write_setup(struct cqspi_flash_pdata *f_pdata,
 	reg &= ~CQSPI_REG_SIZE_ADDRESS_MASK;
 	reg |= (op->addr.nbytes - 1);
 	writel(reg, reg_base + CQSPI_REG_SIZE);
+	readl(reg_base + CQSPI_REG_SIZE); /* Flush posted write. */
 	return 0;
 }
 
@@ -1090,6 +1093,8 @@ static int cqspi_indirect_write_execute(struct cqspi_flash_pdata *f_pdata,
 	reinit_completion(&cqspi->transfer_complete);
 	writel(CQSPI_REG_INDIRECTWR_START_MASK,
 	       reg_base + CQSPI_REG_INDIRECTWR);
+	readl(reg_base + CQSPI_REG_INDIRECTWR); /* Flush posted write. */
+
 	/*
 	 * As per 66AK2G02 TRM SPRUHY8F section 11.15.5.3 Indirect Access
 	 * Controller programming sequence, couple of cycles of
@@ -1186,7 +1191,7 @@ static void cqspi_chipselect(struct cqspi_flash_pdata *f_pdata)
 		 * CS2 to 4b'1011
 		 * CS3 to 4b'0111
 		 */
-		chip_select = 0xF & ~(1 << chip_select);
+		chip_select = 0xF & ~BIT(chip_select);
 	}
 
 	reg &= ~(CQSPI_REG_CONFIG_CHIPSELECT_MASK
@@ -1272,9 +1277,9 @@ static void cqspi_readdata_capture(struct cqspi_st *cqspi,
 	reg = readl(reg_base + CQSPI_REG_READCAPTURE);
 
 	if (bypass)
-		reg |= (1 << CQSPI_REG_READCAPTURE_BYPASS_LSB);
+		reg |= BIT(CQSPI_REG_READCAPTURE_BYPASS_LSB);
 	else
-		reg &= ~(1 << CQSPI_REG_READCAPTURE_BYPASS_LSB);
+		reg &= ~BIT(CQSPI_REG_READCAPTURE_BYPASS_LSB);
 
 	reg &= ~(CQSPI_REG_READCAPTURE_DELAY_MASK
 		 << CQSPI_REG_READCAPTURE_DELAY_LSB);
@@ -1717,12 +1722,10 @@ static const struct spi_controller_mem_caps cqspi_mem_caps = {
 
 static int cqspi_setup_flash(struct cqspi_st *cqspi)
 {
-	unsigned int max_cs = cqspi->num_chipselect - 1;
 	struct platform_device *pdev = cqspi->pdev;
 	struct device *dev = &pdev->dev;
 	struct cqspi_flash_pdata *f_pdata;
-	unsigned int cs;
-	int ret;
+	int ret, cs, max_cs = -1;
 
 	/* Get flash device data */
 	for_each_available_child_of_node_scoped(dev->of_node, np) {
@@ -1735,10 +1738,10 @@ static int cqspi_setup_flash(struct cqspi_st *cqspi)
 		if (cs >= cqspi->num_chipselect) {
 			dev_err(dev, "Chip select %d out of range.\n", cs);
 			return -EINVAL;
-		} else if (cs < max_cs) {
-			max_cs = cs;
 		}
 
+		max_cs = max_t(int, cs, max_cs);
+
 		f_pdata = &cqspi->f_pdata[cs];
 		f_pdata->cqspi = cqspi;
 		f_pdata->cs = cs;
@@ -1748,6 +1751,11 @@ static int cqspi_setup_flash(struct cqspi_st *cqspi)
 			return ret;
 	}
 
+	if (max_cs < 0) {
+		dev_err(dev, "No flash device declared\n");
+		return -ENODEV;
+	}
+
 	cqspi->num_chipselect = max_cs + 1;
 	return 0;
 }