[PATCH v1] clk: altera: agilex: Exclude AGILEX_L4_SYS_FREE_CLK from enable/disable operations

[alif.zakuan.yuslaimi at altera.com]

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

AGILEX_L4_SYS_FREE_CLK is a free-running clock with no gate control in
hardware, therefore attempting to enable or disable it is not applicable.

Update the clock driver to explicitly exclude this clock ID from
enable/disable operations by returning -EOPNOTSUPP in bitmask_from_clk_id()
and treating this as a no-op in the socfpga_clk_enable() and
socfpga_clk_disable() functions.

This prevents unnecessary register access for clocks that cannot be gated
and ensures clean handling when the clock is present in the device tree.

Signed-off-by: Alif Zakuan Yuslaimi <alif.zakuan.yuslaimi at altera.com>
---
 drivers/clk/altera/clk-agilex.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/clk/altera/clk-agilex.c b/drivers/clk/altera/clk-agilex.c
index fdbf834bb2f..88423292c0b 100644
--- a/drivers/clk/altera/clk-agilex.c
+++ b/drivers/clk/altera/clk-agilex.c
@@ -728,6 +728,8 @@ static int bitmask_from_clk_id(struct clk *clk)
 		plat->pllgrp = CLKMGR_PERPLL_EN;
 		plat->bitmask = CLKMGR_PERPLLGRP_EN_NANDCLK_MASK;
 		break;
+	case AGILEX_L4_SYS_FREE_CLK:
+		return -EOPNOTSUPP;
 	default:
 		return -ENXIO;
 	}
@@ -742,6 +744,9 @@ static int socfpga_clk_enable(struct clk *clk)
 	int ret;
 
 	ret = bitmask_from_clk_id(clk);
+	if (ret == -EOPNOTSUPP)
+		return 0;
+
 	if (ret)
 		return ret;
 
@@ -757,6 +762,9 @@ static int socfpga_clk_disable(struct clk *clk)
 	int ret;
 
 	ret = bitmask_from_clk_id(clk);
+	if (ret == -EOPNOTSUPP)
+		return 0;
+
 	if (ret)
 		return ret;
 
-- 
2.43.7