clk: imx95-blk-ctl: Add func_out_en clock for i.MX9x PCIe

Add a func_out_en clock for i.MX9x PCIe to serve as the parent gate clock
of the CREF_EN (BIT6) gate clock. Both of these two gate clocks enable
the output of the internal 100MHz differential reference clock.

When the internal PLL clock is used as the PCIe reference clock, both
BIT6 (CREF_EN) and BIT2 (FUNC_OUTPUT_EN) control the PCIE_REF_OUT_CLK.

If these bits default to 1, the output clock is enabled. With typical
100-ohm termination on the board, this results in approximately 6mA of
unnecessary power consumption when the PCIe internal PLL clock is not
in use.

To eliminate this power consumption, add a func_out_en clock gate that
serves as the parent of the existing CREF_EN (BIT6) gate clock. Both
gates must be enabled to output the internal 100MHz differential
reference clock, and both will be disabled when the clock is not needed.

Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Link: https://patch.msgid.link/20260730085542.263025-1-hongxing.zhu@oss.nxp.com
Signed-off-by: Abel Vesa <abel.vesa@oss.qualcomm.com>

1 files changed, 12 insertions, 2 deletions

diff --git a/drivers/clk/imx/clk-imx95-blk-ctl.c b/drivers/clk/imx/clk-imx95-blk-ctl.c
index 56bed4471995..1f9259f45607 100644
--- a/drivers/clk/imx/clk-imx95-blk-ctl.c
+++ b/drivers/clk/imx/clk-imx95-blk-ctl.c
@@ -286,18 +286,28 @@ static const struct imx95_blk_ctl_dev_data netcmix_dev_data = {
 static const struct imx95_blk_ctl_clk_dev_data hsio_blk_ctl_clk_dev_data[] = {
 	[0] = {
 		.name = "hsio_blk_ctl_clk",
-		.parent_names = (const char *[]){ "hsio_pll", },
+		.parent_names = (const char *[]){ "func_out_en", },
 		.num_parents = 1,
 		.reg = 0,
 		.bit_idx = 6,
 		.bit_width = 1,
 		.type = CLK_GATE,
 		.flags = CLK_SET_RATE_PARENT,
+	},
+	[1] = {
+		.name = "func_out_en",
+		.parent_names = (const char *[]){ "hsio_pll", },
+		.num_parents = 1,
+		.reg = 0,
+		.bit_idx = 2,
+		.bit_width = 1,
+		.type = CLK_GATE,
+		.flags = CLK_SET_RATE_PARENT,
 	}
 };
 
 static const struct imx95_blk_ctl_dev_data hsio_blk_ctl_dev_data = {
-	.num_clks = 1,
+	.num_clks = ARRAY_SIZE(hsio_blk_ctl_clk_dev_data),
 	.clk_dev_data = hsio_blk_ctl_clk_dev_data,
 	.clk_reg_offset = 0,
 };