linux-kernel - [PATCH v1] soc: imx: imx8mp-blk-ctrl: Add PCIe SYSPLL configurations

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Date:   Mon, 24 Oct 2022 13:43:09 +0800
From:   Richard Zhu <hongxing.zhu@....com>
To:     l.stach@...gutronix.de, marex@...x.de, tharvey@...eworks.com,
        vkoul@...nel.org, bhelgaas@...gle.com, lorenzo.pieralisi@....com,
        shawnguo@...nel.org, alexander.stein@...tq-group.com,
        richard.leitner@...ux.dev
Cc:     devicetree@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel@...gutronix.de, linux-imx@....com,
        Richard Zhu <hongxing.zhu@....com>
Subject: [PATCH v1] soc: imx: imx8mp-blk-ctrl: Add PCIe SYSPLL configurations

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_ROOT>'.

Signed-off-by: Richard Zhu <hongxing.zhu@....com>
---
Base on 6.1-rc1, and the following PHY changes [1],
the PCIe works fine when SYSPLL is used as reference clock on i.MX8MP
EVK board(schematic-46370) after removing R131/R132/R137/R138, and
populating R135/R136.

[1] https://patchwork.kernel.org/project/linux-pci/cover/1665625622-20551-1-git-send-email-hongxing.zhu@nxp.com/
---
 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