boards: frdm_mcxn947: Enable CACHE64 FlexSPI cache

1. Enable CACHE64 block used by FlexSPI.
2. LPCAC cache is already enabled by SystemInit which
   is called earlier
3. Configure the FlexSPI clock when running in XIP mode
   as we cannot rely on the driver setting this up as it
   may not be enabled.

Signed-off-by: Mahesh Mahadevan <[email protected]>

Author: mmahadevan108

boards/nxp/frdm_mcxn947/board.c

@@ -25,13 +25,6 @@
 /* System clock frequency. */
 extern uint32_t SystemCoreClock;
 
-__ramfunc static void enable_lpcac(void)
-{
-	SYSCON->LPCAC_CTRL |= SYSCON_LPCAC_CTRL_CLR_LPCAC_MASK;
-	SYSCON->LPCAC_CTRL &= ~(SYSCON_LPCAC_CTRL_CLR_LPCAC_MASK |
-				SYSCON_LPCAC_CTRL_DIS_LPCAC_MASK);
-}
-
 /* Update Active mode voltage for OverDrive mode. */
 void power_mode_od(void)
 {
@@ -57,10 +50,38 @@ void power_mode_od(void)
 	SPC_SetSRAMOperateVoltage(SPC0, &cfg);
 }
 
-static int frdm_mcxn947_init(void)
+#if CONFIG_FLASH_MCUX_FLEXSPI_NOR || CONFIG_FLASH_MCUX_FLEXSPI_XIP
+__ramfunc static void enable_cache64(void)
 {
-	enable_lpcac();
+	/* Make sure the FlexSPI clock is enabled before configuring the FlexSPI cache. */
+	SYSCON->AHBCLKCTRLSET[0] |= SYSCON_AHBCLKCTRL0_FLEXSPI_MASK;
+
+	/* Set command to invalidate all ways and write GO bit to initiate command */
+	CACHE64_CTRL0->CCR = CACHE64_CTRL_CCR_INVW1_MASK | CACHE64_CTRL_CCR_INVW0_MASK;
+	CACHE64_CTRL0->CCR |= CACHE64_CTRL_CCR_GO_MASK;
+	/* Wait until the command completes */
+	while ((CACHE64_CTRL0->CCR & CACHE64_CTRL_CCR_GO_MASK) != 0U) {
+	}
+	/* Enable cache, enable write buffer */
+	CACHE64_CTRL0->CCR = (CACHE64_CTRL_CCR_ENWRBUF_MASK | CACHE64_CTRL_CCR_ENCACHE_MASK);
+
+	/* configure reg0, reg1 to cover the whole FlexSPI
+	 * reg 0 covers the space where Zephyr resides in case of XIP from FlexSPI
+	 * reg 1 covers the storage space in case of XIP from FlexSPI
+	 */
+	CACHE64_POLSEL0->REG0_TOP = 0x7FFC00;
+	CACHE64_POLSEL0->REG1_TOP = 0x0;
+	CACHE64_POLSEL0->POLSEL =
+		(CACHE64_POLSEL_POLSEL_REG0_POLICY(1) | CACHE64_POLSEL_POLSEL_REG1_POLICY(0) |
+		 CACHE64_POLSEL_POLSEL_REG2_POLICY(0));
+
+	__ISB();
+	__DSB();
+}
+#endif
 
+static int frdm_mcxn947_init(void)
+{
 	power_mode_od();
 
 	/* Enable SCG clock */
@@ -232,12 +253,11 @@ static int frdm_mcxn947_init(void)
 	CLOCK_AttachClk(kFRO_HF_to_USDHC);
 #endif
 
-#if CONFIG_FLASH_MCUX_FLEXSPI_NOR
-	/* We downclock the FlexSPI to 50MHz, it will be set to the
-	 * optimum speed supported by the Flash device during FLEXSPI
-	 * Init
-	 */
-	flexspi_clock_set_freq(MCUX_FLEXSPI_CLK, MHZ(50));
+#if CONFIG_FLASH_MCUX_FLEXSPI_NOR || CONFIG_FLASH_MCUX_FLEXSPI_XIP
+	/* Setup the FlexSPI clock */
+	flexspi_clock_set_freq(MCUX_FLEXSPI_CLK,
+			       DT_PROP(DT_NODELABEL(w25q64jvssiq), spi_max_frequency));
+	enable_cache64();
 #endif
 
 #if DT_NODE_HAS_STATUS(DT_NODELABEL(vref), okay)