[PATCH master 5/5] ARM: i.MX8M: order early clock init like U-Boot

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

The clocks configured in __imx8m_early_clock_init() now match U-Boot's
clock_init(), but are written in a different order: DRAM first, then
GIC, SYS_PLL3, NOC and the ARM PLL last.

U-Boot sets up the ARM PLL right after enabling the SYS_PLL1/2 outputs,
then SYS_PLL3 and its NOC consumer, the GIC root and the DRAM clocks
last. Reorder to the same sequence, so the two can be compared side by
side. The remaining differences are:

  - barebox doesn't touch the NAND_USDHC_BUS and watchdog roots or the
    TEMP_SENSOR and SEC_DEBUG gates in the PBL

  - NXP's downstream U-Boot additionally configures the display clocks
    in clock_init() (VIDEO_PLL at 594MHz, the DISPLAY_AXI/APB and MIPI
    DSI roots, DISPMIX gate)

These are skipped as both barebox and Linux will configure these clocks
if needed before using them.

Every root and gate ends up with the same value, and each source is
enabled before a root is switched to it in either order.

No functional change.

Assisted-by: Claude:fable-5.1
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 arch/arm/mach-imx/imx8m.c | 83 +++++++++++++++++++--------------------
 1 file changed, 40 insertions(+), 43 deletions(-)

diff --git a/arch/arm/mach-imx/imx8m.c b/arch/arm/mach-imx/imx8m.c
index 23a920ffae2e..b9f8906d6ed2 100644
--- a/arch/arm/mach-imx/imx8m.c
+++ b/arch/arm/mach-imx/imx8m.c
@@ -82,6 +82,46 @@ static void __imx8m_early_clock_init(int cpu_type)
 		INTPLL_DIV20_CLKE_MASK;
 	writel(val, ana + IMX8MM_CCM_ANALOG_SYS_PLL2_GEN_CTRL);
 
+	/* Configure ARM at 1.2GHz */
+	imx8m_clock_set_target_val(IMX8M_ARM_A53_CLK_ROOT,
+				   IMX8M_CCM_TARGET_ROOTn_ENABLE |
+				   IMX8M_CCM_TARGET_ROOTn_MUX(2));
+
+	clk_pll1416x_early_configure(ana + IMX8MM_CCM_ANALOG_ARM_PLL_GEN_CTRL,
+				     1200000000UL, 25000000UL);
+
+	/* Bypass the A53 root and feed the cores from arm_pll_out directly */
+	imx8m_clock_set_target_val(IMX8M_CORE_SEL_CFG,
+				   IMX8M_CCM_TARGET_ROOTn_MUX(1));
+
+	if (cpu_type == IMX_CPU_IMX8MN || cpu_type == IMX_CPU_IMX8MP)
+		pll3_freq = 600000000UL;
+	else
+		pll3_freq = 750000000UL;
+
+	/* Configure SYS_PLL3 */
+	clk_pll1416x_early_configure(ana + IMX8MM_CCM_ANALOG_SYS_PLL3_GEN_CTRL,
+				     pll3_freq, 25000000UL);
+
+	if (cpu_type == IMX_CPU_IMX8MP) {
+		/* NOC_IO from sys_pll3_out, barebox proper sets NOC and GIC */
+		imx8m_clock_set_target_val(IMX8M_NOC_IO_CLK_ROOT,
+					   IMX8M_CCM_TARGET_ROOTn_ENABLE |
+					   IMX8M_CCM_TARGET_ROOTn_MUX(2));
+	} else {
+		/* NOC from undivided sys_pll3_out */
+		imx8m_clock_set_target_val(IMX8M_NOC_CLK_ROOT,
+					   IMX8M_CCM_TARGET_ROOTn_ENABLE |
+					   IMX8M_CCM_TARGET_ROOTn_MUX(2));
+
+		/* config GIC to sys_pll2_100m */
+		imx8m_ccgr_clock_disable(IMX8M_CCM_CCGR_GIC);
+		imx8m_clock_set_target_val(IMX8M_GIC_CLK_ROOT,
+					   IMX8M_CCM_TARGET_ROOTn_ENABLE |
+					   IMX8M_CCM_TARGET_ROOTn_MUX(3));
+		imx8m_ccgr_clock_enable(IMX8M_CCM_CCGR_GIC);
+	}
+
 	imx8m_ccgr_clock_disable(IMX8M_CCM_CCGR_DDR1);
 
 	imx8m_clock_set_target_val(IMX8M_DRAM_ALT_CLK_ROOT,
@@ -94,49 +134,6 @@ static void __imx8m_early_clock_init(int cpu_type)
 				   IMX8M_CCM_TARGET_ROOTn_MUX(1));
 
 	imx8m_ccgr_clock_enable(IMX8M_CCM_CCGR_DDR1);
-
-	if (cpu_type != IMX_CPU_IMX8MP) {
-		/* 8MP ROM already set GIC to 400Mhz, system_pll1_800m with div = 2 */
-		/* For everything else, config GIC to sys_pll2_100m */
-		imx8m_ccgr_clock_disable(IMX8M_CCM_CCGR_GIC);
-		imx8m_clock_set_target_val(IMX8M_GIC_CLK_ROOT,
-					   IMX8M_CCM_TARGET_ROOTn_ENABLE |
-					   IMX8M_CCM_TARGET_ROOTn_MUX(3));
-		imx8m_ccgr_clock_enable(IMX8M_CCM_CCGR_GIC);
-	}
-
-	if (cpu_type == IMX_CPU_IMX8MN || cpu_type == IMX_CPU_IMX8MP)
-		pll3_freq = 600000000UL;
-	else
-		pll3_freq = 750000000UL;
-
-	/* Configure SYS_PLL3 */
-	clk_pll1416x_early_configure(ana + IMX8MM_CCM_ANALOG_SYS_PLL3_GEN_CTRL,
-				     pll3_freq, 25000000UL);
-
-	if (cpu_type == IMX_CPU_IMX8MP) {
-		/* 8MP ROM already set NOC to 800Mhz, only need to configure NOC_IO clk to 600Mhz */
-		imx8m_clock_set_target_val(IMX8M_NOC_IO_CLK_ROOT,
-					   IMX8M_CCM_TARGET_ROOTn_ENABLE |
-					   IMX8M_CCM_TARGET_ROOTn_MUX(2));
-	} else {
-		/* NOC from undivided sys_pll3_out */
-		imx8m_clock_set_target_val(IMX8M_NOC_CLK_ROOT,
-					   IMX8M_CCM_TARGET_ROOTn_ENABLE |
-					   IMX8M_CCM_TARGET_ROOTn_MUX(2));
-	}
-
-	imx8m_clock_set_target_val(IMX8M_ARM_A53_CLK_ROOT,
-				   IMX8M_CCM_TARGET_ROOTn_ENABLE |
-				   IMX8M_CCM_TARGET_ROOTn_MUX(2));
-
-	/* Configure ARM PLL to 1.2GHz */
-	clk_pll1416x_early_configure(ana + IMX8MM_CCM_ANALOG_ARM_PLL_GEN_CTRL,
-				     1200000000UL, 25000000UL);
-
-	/* Bypass the A53 root and feed the cores from arm_pll_out directly */
-	imx8m_clock_set_target_val(IMX8M_CORE_SEL_CFG,
-				   IMX8M_CCM_TARGET_ROOTn_MUX(1));
 }
 
 void imx8mm_early_clock_init(void)
-- 
2.47.3