[PATCH v2 03/26] drivers: clk: agilex5: Configure intosc as boot_clk source

[alif.zakuan.yuslaimi at intel.com]

From: Alif Zakuan Yuslaimi <alif.zakuan.yuslaimi at intel.com>

Some customers prefer to minimize the use of external oscillators,
especially when using the FPGA first configuration mode.

By enabling the configuration of the HPS internal oscillator as
the boot_clk source instead of the default external oscillator,
(HPS_OSC_CLK) in non-secure boot scenarios, this allows them
to eliminate the need for an additional oscillator device and
a dedicated HPS pin, simplifying board layout and routing.

Signed-off-by: Tingting Meng <tingting.meng at altera.com>
Signed-off-by: Alif Zakuan Yuslaimi <alif.zakuan.yuslaimi at altera.com>
---
 drivers/clk/altera/clk-agilex5.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/clk/altera/clk-agilex5.c b/drivers/clk/altera/clk-agilex5.c
index 716c71598bc..dfc25ac6787 100644
--- a/drivers/clk/altera/clk-agilex5.c
+++ b/drivers/clk/altera/clk-agilex5.c
@@ -1,13 +1,13 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2024 Intel Corporation <www.intel.com>
+ * Copyright (C) 2025 Altera Corporation <www.altera.com>
  */
 
-#include <clk-uclass.h>
 #include <config.h>
-#include <errno.h>
-#include <dm.h>
 #include <log.h>
+#include <dm.h>
+#include <errno.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <time.h>
@@ -23,9 +23,14 @@
 #include <linux/types.h>
 #include <asm/arch/clock_manager.h>
 #include <dt-bindings/clock/agilex5-clock.h>
+#include <wait_bit.h>
+#include <clk-uclass.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
+#define CLKMGR_CTRL_SWCTRLBTCLKEN_MASK		BIT(8)
+#define CLKMGR_CTRL_SWCTRLBTCLKSEL_MASK		BIT(9)
+
 struct socfpga_clk_plat {
 	void __iomem *regs;
 };
@@ -264,9 +269,14 @@ static void clk_basic_init(struct udevice *dev,
 			       CM_REG_READL(plat, CLKMGR_CTRL) & ~CLKMGR_CTRL_BOOTMODE);
 	} else {
 #ifdef CONFIG_XPL_BUILD
-		/* Always force clock manager into boot mode before any configuration */
-		clk_write_ctrl(plat,
-			       CM_REG_READL(plat, CLKMGR_CTRL) | CLKMGR_CTRL_BOOTMODE);
+		/*
+		 * Configure HPS Internal Oscillator as default boot_clk source,
+		 * always force clock manager into boot mode before any configuration
+		 */
+		clk_write_ctrl(plat, CM_REG_READL(plat, CLKMGR_CTRL) |
+			       CLKMGR_CTRL_BOOTMODE |
+			       CLKMGR_CTRL_SWCTRLBTCLKEN_MASK |
+			       CLKMGR_CTRL_SWCTRLBTCLKSEL_MASK);
 #else
 		/* Skip clock configuration in SSBL if it's not in boot mode */
 		if (!(CM_REG_READL(plat, CLKMGR_CTRL) & CLKMGR_CTRL_BOOTMODE))
-- 
2.25.1