spi: cadence: Add clock configuration for Marvell xSPI overlay

Add support for clock divider. Divider block can disable, enable and
divide clock signal. Only 14 different divide ratios are avalible, from
6.25 up to 200MHz. For calculations use default Marvell system clock
value(800MHz).
Signed-off-by: Witold Sadowski <wsadowski@marvell.com>
Link: https://patch.msgid.link/20240724154739.582367-4-wsadowski@marvell.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-cadence-xspi.c

@@ -217,6 +217,15 @@
 #define CDNS_XSPI_DLL_RST_N BIT(24)
 #define CDNS_XSPI_DLL_LOCK  BIT(0)
 
+/* Marvell overlay registers - clock */
+#define MRVL_XSPI_CLK_CTRL_AUX_REG   0x2020
+#define MRVL_XSPI_CLK_ENABLE	     BIT(0)
+#define MRVL_XSPI_CLK_DIV	     GENMASK(4, 1)
+#define MRVL_XSPI_IRQ_ENABLE	     BIT(6)
+#define MRVL_XSPI_CLOCK_IO_HZ	     800000000
+#define MRVL_XSPI_CLOCK_DIVIDED(div) ((MRVL_XSPI_CLOCK_IO_HZ) / (div))
+#define MRVL_DEFAULT_CLK	     25000000
+
 enum cdns_xspi_stig_instr_type {
 	CDNS_XSPI_STIG_INSTR_TYPE_0,
 	CDNS_XSPI_STIG_INSTR_TYPE_1,
@@ -261,6 +270,23 @@ static struct cdns_xspi_driver_data cdns_driver_data = {
 	.mrvl_hw_overlay = false,
 };
 
+const int cdns_mrvl_xspi_clk_div_list[] = {
+	4,	//0x0 = Divide by 4.   SPI clock is 200 MHz.
+	6,	//0x1 = Divide by 6.   SPI clock is 133.33 MHz.
+	8,	//0x2 = Divide by 8.   SPI clock is 100 MHz.
+	10,	//0x3 = Divide by 10.  SPI clock is 80 MHz.
+	12,	//0x4 = Divide by 12.  SPI clock is 66.666 MHz.
+	16,	//0x5 = Divide by 16.  SPI clock is 50 MHz.
+	18,	//0x6 = Divide by 18.  SPI clock is 44.44 MHz.
+	20,	//0x7 = Divide by 20.  SPI clock is 40 MHz.
+	24,	//0x8 = Divide by 24.  SPI clock is 33.33 MHz.
+	32,	//0x9 = Divide by 32.  SPI clock is 25 MHz.
+	40,	//0xA = Divide by 40.  SPI clock is 20 MHz.
+	50,	//0xB = Divide by 50.  SPI clock is 16 MHz.
+	64,	//0xC = Divide by 64.  SPI clock is 12.5 MHz.
+	128	//0xD = Divide by 128. SPI clock is 6.25 MHz.
+};
+
 struct cdns_xspi_dev {
 	struct platform_device *pdev;
 	struct device *dev;
@@ -331,6 +357,48 @@ static bool cdns_xspi_configure_phy(struct cdns_xspi_dev *cdns_xspi)
 	return cdns_xspi_is_dll_locked(cdns_xspi);
 }
 
+static bool cdns_mrvl_xspi_setup_clock(struct cdns_xspi_dev *cdns_xspi,
+				       int requested_clk)
+{
+	int i = 0;
+	int clk_val;
+	u32 clk_reg;
+	bool update_clk = false;
+
+	while (i < ARRAY_SIZE(cdns_mrvl_xspi_clk_div_list)) {
+		clk_val = MRVL_XSPI_CLOCK_DIVIDED(
+				cdns_mrvl_xspi_clk_div_list[i]);
+		if (clk_val <= requested_clk)
+			break;
+		i++;
+	}
+
+	dev_dbg(cdns_xspi->dev, "Found clk div: %d, clk val: %d\n",
+		cdns_mrvl_xspi_clk_div_list[i],
+		MRVL_XSPI_CLOCK_DIVIDED(
+		cdns_mrvl_xspi_clk_div_list[i]));
+
+	clk_reg = readl(cdns_xspi->auxbase + MRVL_XSPI_CLK_CTRL_AUX_REG);
+
+	if (FIELD_GET(MRVL_XSPI_CLK_DIV, clk_reg) != i) {
+		clk_reg &= ~MRVL_XSPI_CLK_ENABLE;
+		writel(clk_reg,
+		       cdns_xspi->auxbase + MRVL_XSPI_CLK_CTRL_AUX_REG);
+		clk_reg = FIELD_PREP(MRVL_XSPI_CLK_DIV, i);
+		clk_reg &= ~MRVL_XSPI_CLK_DIV;
+		clk_reg |= FIELD_PREP(MRVL_XSPI_CLK_DIV, i);
+		clk_reg |= MRVL_XSPI_CLK_ENABLE;
+		clk_reg |= MRVL_XSPI_IRQ_ENABLE;
+		update_clk = true;
+	}
+
+	if (update_clk)
+		writel(clk_reg,
+		       cdns_xspi->auxbase + MRVL_XSPI_CLK_CTRL_AUX_REG);
+
+	return update_clk;
+}
+
 static int cdns_xspi_wait_for_controller_idle(struct cdns_xspi_dev *cdns_xspi)
 {
 	u32 ctrl_stat;
@@ -536,6 +604,21 @@ static int cdns_xspi_mem_op_execute(struct spi_mem *mem,
 	return ret;
 }
 
+static int marvell_xspi_mem_op_execute(struct spi_mem *mem,
+				    const struct spi_mem_op *op)
+{
+	struct cdns_xspi_dev *cdns_xspi =
+		spi_controller_get_devdata(mem->spi->controller);
+	int ret = 0;
+
+	cdns_mrvl_xspi_setup_clock(cdns_xspi, mem->spi->max_speed_hz);
+
+	ret = cdns_xspi_mem_op(cdns_xspi, mem, op);
+
+	return ret;
+}
+
+
 static int cdns_xspi_adjust_mem_op_size(struct spi_mem *mem, struct spi_mem_op *op)
 {
 	struct cdns_xspi_dev *cdns_xspi =
@@ -551,6 +634,11 @@ static const struct spi_controller_mem_ops cadence_xspi_mem_ops = {
 	.adjust_op_size = cdns_xspi_adjust_mem_op_size,
 };
 
+static const struct spi_controller_mem_ops marvell_xspi_mem_ops = {
+	.exec_op = marvell_xspi_mem_op_execute,
+	.adjust_op_size = cdns_xspi_adjust_mem_op_size,
+};
+
 static irqreturn_t cdns_xspi_irq_handler(int this_irq, void *dev)
 {
 	struct cdns_xspi_dev *cdns_xspi = dev;
@@ -648,6 +736,9 @@ static int cdns_xspi_probe(struct platform_device *pdev)
 	if (!cdns_xspi->driver_data)
 		return -ENODEV;
 
+	if (cdns_xspi->driver_data->mrvl_hw_overlay)
+		host->mem_ops = &marvell_xspi_mem_ops;
+	else
 		host->mem_ops = &cadence_xspi_mem_ops;
 	host->dev.of_node = pdev->dev.of_node;
 	host->bus_num = -1;
@@ -695,8 +786,10 @@ static int cdns_xspi_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	if (cdns_xspi->driver_data->mrvl_hw_overlay)
+	if (cdns_xspi->driver_data->mrvl_hw_overlay) {
+		cdns_mrvl_xspi_setup_clock(cdns_xspi, MRVL_DEFAULT_CLK);
 		cdns_xspi_configure_phy(cdns_xspi);
+	}
 
 	cdns_xspi_print_phy_config(cdns_xspi);