[PATCH v1 3/4] clk: agilex: Handle clock configuration differently in SPL and U-Boot proper

[Chee Hong Ang]

Since warm reset may optionally set the CLock Manager to'boot mode',
the clock driver should always force the Agilex's Clock Manager to
'boot mode' before the clock driver start configuring the Clock Manager
in SPL.
In SSBL, clock driver will skip the Clock Manager configuration
if it's already being setup by SPL (Clock Manager NOT in 'boot
mode') to prevent any inaccurate clocking issues happened on HPS
peripherals such as UART, MAC and etc.

Signed-off-by: Chee Hong Ang <chee.hong.ang at intel.com>
---
 drivers/clk/altera/clk-agilex.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/clk/altera/clk-agilex.c b/drivers/clk/altera/clk-agilex.c
index b5cf187364..c83eb2efb9 100644
--- a/drivers/clk/altera/clk-agilex.c
+++ b/drivers/clk/altera/clk-agilex.c
@@ -171,6 +171,16 @@ static void clk_basic_init(struct udevice *dev,
 	if (!cfg)
 		return;
 
+#ifdef CONFIG_SPL_BUILD
+	/* Always force clock manager into boot mode before any configuration */
+	clk_write_ctrl(plat,
+		       CM_REG_READL(plat, CLKMGR_CTRL) | CLKMGR_CTRL_BOOTMODE);
+#else
+	/* Skip clock configuration in SSBL if it's not in boot mode */
+	if (!(CM_REG_READL(plat, CLKMGR_CTRL) & CLKMGR_CTRL_BOOTMODE))
+		return;
+#endif
+
 	/* Put both PLLs in bypass */
 	clk_write_bypass_mainpll(plat, CLKMGR_BYPASS_MAINPLL_ALL);
 	clk_write_bypass_perpll(plat, CLKMGR_BYPASS_PERPLL_ALL);
-- 
2.19.0