[PATCH v2] soc: imx: imx8mp-blk-ctrl: Add PCIe SYSPLL configurations

[Richard Zhu <hongxing.zhu@nxp.com>]

Add PCIe SYSPLL configurations, thus the internal SYSPLL can be used as
i.MX8MP PCIe reference clock.

The following properties of PHY dts node should be changed accordingly.
  - Set 'fsl,refclk-pad-mode' as '<IMX8_PCIE_REFCLK_PAD_OUTPUT>'.
  - Change 'clocks' to '<&clk IMX8MP_CLK_HSIO_AXI>'.

Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
---
v1->v2:
Refer to Lucas' comments, don't expose IMX8MP_CLK_HSIO_ROOT to dts node.
https://patchwork.ozlabs.org/project/linux-pci/patch/1666590189-1364-1-git-send-email-hongxing.zhu@nxp.com/

Use <&clk IMX8MP_CLK_HSIO_AXI> as referrence clock source when internal
clock mode is used by i.MX8MP PCIe module.

Verified on i.MX8MP EVK board with removing R131/R132/R137/R138, and
populating R135/R136.
---
 drivers/soc/imx/imx8mp-blk-ctrl.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/soc/imx/imx8mp-blk-ctrl.c b/drivers/soc/imx/imx8mp-blk-ctrl.c
index 0e3b6ba22f94..5ad20a8ea25e 100644
--- a/drivers/soc/imx/imx8mp-blk-ctrl.c
+++ b/drivers/soc/imx/imx8mp-blk-ctrl.c
@@ -21,6 +21,16 @@
 #define  USB_CLOCK_MODULE_EN	BIT(1)
 #define  PCIE_PHY_APB_RST	BIT(4)
 #define  PCIE_PHY_INIT_RST	BIT(5)
+#define GPR_REG2		0x8
+#define  P_PLL_MASK		GENMASK(5, 0)
+#define  M_PLL_MASK		GENMASK(15, 6)
+#define  S_PLL_MASK		GENMASK(18, 16)
+#define  P_PLL			(0xc << 0)
+#define  M_PLL			(0x320 << 6)
+#define  S_PLL			(0x4 << 16)
+#define GPR_REG3		0xc
+#define  PLL_CKE		BIT(17)
+#define  PLL_RST		BIT(31)
 
 struct imx8mp_blk_ctrl_domain;
 
@@ -86,6 +96,18 @@ static void imx8mp_hsio_blk_ctrl_power_on(struct imx8mp_blk_ctrl *bc,
 	case IMX8MP_HSIOBLK_PD_PCIE_PHY:
 		regmap_set_bits(bc->regmap, GPR_REG0,
 				PCIE_PHY_APB_RST | PCIE_PHY_INIT_RST);
+
+		/* Set the PLL configurations, P = 12, M = 800, S = 4. */
+		regmap_update_bits(bc->regmap, GPR_REG2,
+				   P_PLL_MASK | M_PLL_MASK | S_PLL_MASK,
+				   P_PLL | M_PLL | S_PLL);
+		udelay(1);
+
+		regmap_update_bits(bc->regmap, GPR_REG3, PLL_RST, PLL_RST);
+		udelay(10);
+
+		/* Set 1b'1 to pll_cke of GPR_REG3 */
+		regmap_update_bits(bc->regmap, GPR_REG3, PLL_CKE, PLL_CKE);
 		break;
 	default:
 		break;
-- 
2.25.1