Introduce a driver that supports three PHYs found on the SpacemiT
K1 SoC.  The first PHY is a combo PHY that can be configured for
use for either USB 3 or PCIe.  The other two PHYs support PCIe
only.

All three PHYs must be programmed with an 8 bit receiver termination
value, which must be determined dynamically; only the combo PHY is
able to determine this value.  The combo PHY performs a special
calibration step at probe time to discover this, and that value is
used to program each PHY that operates in PCIe mode.  The combo
PHY must therefore be probed--first--if either of the PCIe-only
PHYs will be used.

During normal operation, the USB or PCIe driver using the PHY must
ensure clocks and resets are set up properly.  However clocks are
enabled and resets are de-asserted temporarily by this driver to
perform the calibration step on the combo PHY.

Tested-by: Junzhong Pan <redacted>
Signed-off-by: Alex Elder <redacted>
---
 drivers/phy/Kconfig                |  11 +
 drivers/phy/Makefile               |   1 +
 drivers/phy/phy-spacemit-k1-pcie.c | 639 +++++++++++++++++++++++++++++
 3 files changed, 651 insertions(+)
 create mode 100644 drivers/phy/phy-spacemit-k1-pcie.c

diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig
index 58c911e1b2d20..0fa343203f289 100644
--- a/drivers/phy/Kconfig
+++ b/drivers/phy/Kconfig

@@ -101,6 +101,17 @@ config PHY_NXP_PTN3222
 	  schemes. It supports all three USB 2.0 data rates: Low Speed, Full
 	  Speed and High Speed.
 
+config PHY_SPACEMIT_K1_PCIE
+	tristate "PCIe and combo PHY driver for the SpacemiT K1 SoC"
+	depends on ARCH_SPACEMIT || COMPILE_TEST
+	depends on HAS_IOMEM
+	depends on OF
+	select GENERIC_PHY
+	default ARCH_SPACEMIT
+	help
+	  Enable support for the PCIe and USB 3 combo PHY and two
+	  PCIe-only PHYs used in the SpacemiT K1 SoC.
+
 source "drivers/phy/allwinner/Kconfig"
 source "drivers/phy/amlogic/Kconfig"
 source "drivers/phy/broadcom/Kconfig"

diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile
index c670a8dac4680..20f0078e543c7 100644
--- a/drivers/phy/Makefile
+++ b/drivers/phy/Makefile

@@ -13,6 +13,7 @@ obj-$(CONFIG_PHY_SNPS_EUSB2)		+= phy-snps-eusb2.o
 obj-$(CONFIG_USB_LGM_PHY)		+= phy-lgm-usb.o
 obj-$(CONFIG_PHY_AIROHA_PCIE)		+= phy-airoha-pcie.o
 obj-$(CONFIG_PHY_NXP_PTN3222)		+= phy-nxp-ptn3222.o
+obj-$(CONFIG_PHY_SPACEMIT_K1_PCIE)	+= phy-spacemit-k1-pcie.o
 obj-y					+= allwinner/	\
 					   amlogic/	\
 					   broadcom/	\

diff --git a/drivers/phy/phy-spacemit-k1-pcie.c b/drivers/phy/phy-spacemit-k1-pcie.c
new file mode 100644
index 0000000000000..32dce53170fbb
--- /dev/null
+++ b/drivers/phy/phy-spacemit-k1-pcie.c

@@ -0,0 +1,639 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SpacemiT K1 PCIe and PCIe/USB 3 combo PHY driver
+ *
+ * Copyright (C) 2025 by RISCstar Solutions Corporation.  All rights reserved.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/reset.h>
+
+#include <dt-bindings/phy/phy.h>
+
+/*
+ * Three PCIe ports are supported in the SpacemiT K1 SoC, and this driver
+ * supports their PHYs.
+ *
+ * The PHY for PCIe port A is different from the PHYs for ports B and C:
+ * - It has one lane, while ports B and C have two
+ * - It is a combo PHY can be used for PCIe or USB 3
+ * - It can automatically calibrate PCIe TX and RX termination settings
+ *
+ * The PHY functionality for PCIe ports B and C is identical:
+ * - They have two PCIe lanes (but can be restricted to 1 via Device Tree)
+ * - They are used for PCIe only
+ * - They are configured using TX and RX values computed for port A
+ *
+ * A given board is designed to use the combo PHY for either PCIe or USB 3.
+ * Whether the combo PHY is configured for PCIe or USB 3 is specified in
+ * Device Tree using a phandle plus an argument.  The argument indicates
+ * the type (either PHY_TYPE_PCIE or PHY_TYPE_USB3).
+ *
+ * Each PHY depends on clocks and resets provided by the controller
+ * hardware (PCIe or USB) it is associated with.  The controller drivers
+ * are required to enable any clocks and de-assert any resets that affect
+ * PHY operation.
+ *
+ * PCIe PHYs must be programmed with RX and TX calibration values.  The
+ * combo PHY is the only one that can determine these values.  They are
+ * determined by temporarily enabling the combo PHY in PCIe mode at probe
+ * time (if necessary).  This calibration only needs to be done once, and
+ * when it has completed the TX and RX values are saved.
+ *
+ * To allow the combo PHY to be enabled for calibration, the resets and
+ * clocks it uses in PCIe mode must be supplied.
+ */
+
+struct k1_pcie_phy {
+	struct device *dev;		/* PHY provider device */
+	struct phy *phy;
+	void __iomem *regs;
+	u32 pcie_lanes;			/* Max unless limited by DT */
+	/* The remaining fields are only used for the combo PHY */
+	u32 type;			/* PHY_TYPE_PCIE or PHY_TYPE_USB3 */
+	struct regmap *pmu;
+};
+
+#define CALIBRATION_TIMEOUT		500000	/* microseconds */
+#define PLL_TIMEOUT			500000	/* microseconds */
+#define POLL_DELAY			500	/* microseconds */
+
+/* Selecting the combo PHY operating mode requires PMU regmap access */
+#define SYSCON_PMU			"spacemit,syscon-pmu"
+
+/* PMU space, for selecting between PCIe and USB3 mode on the combo PHY */
+
+#define PMUA_USB_PHY_CTRL0			0x0110
+#define COMBO_PHY_SEL			BIT(3)	/* 0: PCIe; 1: USB3 */
+
+#define PCIE_CLK_RES_CTRL			0x03cc
+#define PCIE_APP_HOLD_PHY_RST		BIT(30)
+
+/* PHY register space */
+
+/* Offset between lane 0 and lane 1 registers when there are two */
+#define PHY_LANE_OFFSET				0x0400
+
+#define PCIE_PU_ADDR_CLK_CFG			0x0008
+#define PLL_READY			BIT(0)		/* read-only */
+#define CFG_RXCLK_EN			BIT(3)
+#define CFG_TXCLK_EN			BIT(4)
+#define CFG_PCLK_EN			BIT(5)
+#define CFG_PIPE_PCLK_EN		BIT(6)
+#define CFG_INTERNAL_TIMER_ADJ		GENMASK(10, 7)
+#define TIMER_ADJ_USB		0x2
+#define TIMER_ADJ_PCIE		0x6
+#define CFG_SW_PHY_INIT_DONE		BIT(11)	/* We set after PLL config */
+
+#define PCIE_RC_DONE_STATUS			0x0018
+#define CFG_FORCE_RCV_RETRY		BIT(10)
+
+#define PCIE_RC_CAL_REG2			0x0020
+#define RC_CAL_TOGGLE			BIT(22)
+#define CLKSEL				GENMASK(31, 29)
+#define CLKSEL_24M		0x3
+
+#define PCIE_PU_PLL_1				0x0048
+#define REF_100_WSSC			BIT(12)	/* 1: input is 100MHz, SSC */
+#define FREF_SEL			GENMASK(15, 13)
+#define FREF_24M		0x1
+#define SSC_DEP_SEL			GENMASK(19, 16)
+#define SSC_DEP_NONE		0x0
+#define SSC_DEP_5000PPM		0xa
+#define SSC_MODE			GENMASK(21, 20)
+#define SSC_MODE_DOWN_SPREAD	0x3
+#define SSC_OFFSET			GENMASK(23, 22)
+#define SSC_OFFSET_0_PPM	0x0
+
+#define PCIE_PU_PLL_2				0x004c
+#define GEN_REF100			BIT(4)	/* 1: generate 100MHz clk */
+
+#define PCIE_RX_REG1				0x0050
+#define EN_RTERM			BIT(3)
+#define AFE_RTERM_REG			GENMASK(11, 8)
+
+#define PCIE_RX_REG2				0x0054
+#define RX_RTERM_SEL			BIT(5)	/* 0: use AFE_RTERM_REG value */
+
+#define PCIE_LTSSM_DIS_ENTRY			0x005c
+#define CFG_REFCLK_MODE			GENMASK(9, 8)
+#define RFCLK_MODE_DRIVER	0x1
+#define OVRD_REFCLK_MODE		BIT(10)	/* 1: use CFG_RFCLK_MODE */
+
+#define PCIE_TX_REG1				0x0064
+#define TX_RTERM_REG			GENMASK(15, 12)
+#define TX_RTERM_SEL			BIT(25)	/* 1: use TX_RTERM_REG */
+
+#define USB3_TEST_CTRL				0x0068
+
+#define PCIE_RCAL_RESULT			0x0084	/* Port A PHY only */
+#define RTERM_VALUE_RX			GENMASK(3, 0)
+#define RTERM_VALUE_TX			GENMASK(7, 4)
+#define R_TUNE_DONE			BIT(10)
+
+static u32 k1_phy_rterm = ~0;     /* Invalid initial value */
+
+/* Save the RX and TX receiver termination values */
+static void k1_phy_rterm_set(u32 val)
+{
+	k1_phy_rterm = val & (RTERM_VALUE_RX | RTERM_VALUE_TX);
+}
+
+static bool k1_phy_rterm_valid(void)
+{
+	/* Valid if no bits outside those we care about are set */
+	return !(k1_phy_rterm & ~(RTERM_VALUE_RX | RTERM_VALUE_TX));
+}
+
+static u32 k1_phy_rterm_rx(void)
+{
+	return FIELD_GET(RTERM_VALUE_RX, k1_phy_rterm);
+}
+
+static u32 k1_phy_rterm_tx(void)
+{
+	return FIELD_GET(RTERM_VALUE_TX, k1_phy_rterm);
+}
+
+/* Only the combo PHY has a PMU pointer defined */
+static bool k1_phy_port_a(struct k1_pcie_phy *k1_phy)
+{
+	return !!k1_phy->pmu;
+}
+
+/*
+ * Select PCIe or USB 3 mode for the combo PHY.  Return 1 if the bit
+ * was changed, 0 if it was not, or a negative error value otherwise.
+ */
+static int k1_combo_phy_sel(struct k1_pcie_phy *k1_phy, bool usb3)
+{
+	int ret;
+
+	ret = regmap_test_bits(k1_phy->pmu, PMUA_USB_PHY_CTRL0, COMBO_PHY_SEL);
+	if (ret < 0)
+		return ret;
+
+	/* If it's already in the desired state, we're done */
+	if (!!ret == usb3)
+		return 0;
+
+	/* Change the bit */
+	ret = regmap_assign_bits(k1_phy->pmu, PMUA_USB_PHY_CTRL0,
+				 COMBO_PHY_SEL, usb3);
+
+	return ret < 0 ? ret : 1;
+}
+