phy: econet: Add PCIe PHY driver for EcoNet EN751221 and EN7528 SoCs.

Introduce support for EcoNet PCIe PHY controllers found in EN751221
and EN7528 SoCs, these SoCs are not identical but are similar, each
having one Gen1 port, and one Gen1/Gen2 port.

Co-developed-by: Ahmed Naseef <naseefkm@gmail.com>
Signed-off-by: Ahmed Naseef <naseefkm@gmail.com>
[cjd@cjdns.fr: add EN751221 support and refactor for clarity]
Signed-off-by: Caleb James DeLisle <cjd@cjdns.fr>
Link: https://patch.msgid.link/20260425173642.406089-3-cjd@cjdns.fr
Signed-off-by: Vinod Koul <vkoul@kernel.org>

MAINTAINERS

@@ -9158,6 +9158,7 @@ M:	Caleb James DeLisle <cjd@cjdns.fr>
 L:	linux-mips@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/phy/econet,en751221-pcie-phy.yaml
+F:	drivers/phy/phy-econet-pcie.c
 
 ECRYPT FILE SYSTEM
 M:	Tyler Hicks <code@tyhicks.com>

drivers/phy/Kconfig

@@ -79,6 +79,18 @@ config PHY_EYEQ5_ETH
 	  shared register region called OLB. If M is selected, the
 	  module will be called phy-eyeq5-eth.
 
+config PHY_ECONET_PCIE
+	tristate "EcoNet PCIe-PHY Driver"
+	depends on ECONET || COMPILE_TEST
+	depends on OF
+	select GENERIC_PHY
+	select REGMAP_MMIO
+	help
+	  Say Y here to add support for EcoNet PCIe PHY driver.
+	  This driver create the basic PHY instance and provides initialize
+	  callback for PCIe GEN1 and GEN2 ports. This PHY is found on
+	  EcoNet SoCs including EN751221 and EN7528.
+
 config PHY_GOOGLE_USB
 	tristate "Google Tensor SoC USB PHY driver"
 	select GENERIC_PHY

drivers/phy/Makefile

@@ -9,6 +9,7 @@ obj-$(CONFIG_GENERIC_PHY)		+= phy-core.o
 obj-$(CONFIG_GENERIC_PHY_MIPI_DPHY)	+= phy-core-mipi-dphy.o
 obj-$(CONFIG_PHY_AIROHA_PCIE)		+= phy-airoha-pcie.o
 obj-$(CONFIG_PHY_CAN_TRANSCEIVER)	+= phy-can-transceiver.o
+obj-$(CONFIG_PHY_ECONET_PCIE)		+= phy-econet-pcie.o
 obj-$(CONFIG_PHY_EYEQ5_ETH)		+= phy-eyeq5-eth.o
 obj-$(CONFIG_PHY_GOOGLE_USB)		+= phy-google-usb.o
 obj-$(CONFIG_USB_LGM_PHY)		+= phy-lgm-usb.o

drivers/phy/phy-econet-pcie.c

@@ -0,0 +1,182 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Author: Caleb James DeLisle <cjd@cjdns.fr>
+ *	   Ahmed Naseef <naseefkm@gmail.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/bits.h>
+#include <linux/delay.h>
+
+/* Rx detection timing for EN751221: 16*8 clock cycles  */
+#define EN751221_RXDET_VAL		16
+
+/* Rx detection timing when in power mode 3 */
+#define EN75_RXDET_P3_REG		0xa28
+#define EN75_RXDET_P3_MASK		GENMASK(17, 9)
+
+/* Rx detection timing when in power mode 2 */
+#define EN75_RXDET_P2_REG		0xa2c
+#define EN75_RXDET_P2_MASK		GENMASK(8, 0)
+
+/* Rx impedance */
+#define EN75_RX_IMPEDANCE_REG		0xb2c
+#define EN75_RX_IMPEDANCE_MASK		GENMASK(13, 12)
+enum en75_rx_impedance {
+	EN75_RX_IMPEDANCE_100_OHM	= 0,
+	EN75_RX_IMPEDANCE_95_OHM	= 1,
+	EN75_RX_IMPEDANCE_90_OHM	= 2,
+};
+
+/* PLL Invert clock */
+#define EN75_PLL_PH_INV_REG		0x4a0
+#define EN75_PLL_PH_INV_MASK		BIT(5)
+
+struct en75_phy_op {
+	u32 reg;
+	u32 mask;
+	u32 val;
+};
+
+struct en7528_pcie_phy {
+	struct regmap *regmap;
+	const struct en75_phy_op *data;
+};
+
+/* Port 0 PHY: set LCDDS_CLK_PH_INV for PLL operation */
+static const struct en75_phy_op en7528_phy_gen1[] = {
+	{
+		.reg = EN75_PLL_PH_INV_REG,
+		.mask = EN75_PLL_PH_INV_MASK,
+		.val = 1,
+	},
+	{ /* sentinel */ }
+};
+
+/* EN7528 Port 1 PHY: Rx impedance tuning, target R -5 Ohm */
+static const struct en75_phy_op en7528_phy_gen2[] = {
+	{
+		.reg = EN75_RX_IMPEDANCE_REG,
+		.mask = EN75_RX_IMPEDANCE_MASK,
+		.val = EN75_RX_IMPEDANCE_95_OHM,
+	},
+	{ /* sentinel */ }
+};
+
+/* EN751221 Port 1 PHY, set RX detect to 16*8 clock cycles */
+static const struct en75_phy_op en751221_phy_gen2[] = {
+	{
+		.reg = EN75_RXDET_P3_REG,
+		.mask = EN75_RXDET_P3_MASK,
+		.val = EN751221_RXDET_VAL,
+	},
+	{
+		.reg = EN75_RXDET_P2_REG,
+		.mask = EN75_RXDET_P2_MASK,
+		.val = EN751221_RXDET_VAL,
+	},
+	{ /* sentinel */ }
+};
+
+static int en75_pcie_phy_init(struct phy *phy)
+{
+	struct en7528_pcie_phy *ephy = phy_get_drvdata(phy);
+	const struct en75_phy_op *data = ephy->data;
+	int i, ret;
+	u32 val;
+
+	for (i = 0; data[i].mask || data[i].val; i++) {
+		if (i)
+			usleep_range(1000, 2000);
+
+		val = field_prep(data[i].mask, data[i].val);
+
+		ret = regmap_update_bits(ephy->regmap, data[i].reg,
+					 data[i].mask, val);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static const struct phy_ops en75_pcie_phy_ops = {
+	.init	= en75_pcie_phy_init,
+	.owner	= THIS_MODULE,
+};
+
+static int en75_pcie_phy_probe(struct platform_device *pdev)
+{
+	struct regmap_config regmap_config = {
+		.reg_bits = 32,
+		.val_bits = 32,
+		.reg_stride = 4,
+	};
+	struct device *dev = &pdev->dev;
+	const struct en75_phy_op *data;
+	struct phy_provider *provider;
+	struct en7528_pcie_phy *ephy;
+	void __iomem *base;
+	struct phy *phy;
+	int i;
+
+	data = of_device_get_match_data(dev);
+	if (!data)
+		return -EINVAL;
+
+	ephy = devm_kzalloc(dev, sizeof(*ephy), GFP_KERNEL);
+	if (!ephy)
+		return -ENOMEM;
+
+	ephy->data = data;
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	/* Set max_register to highest used register */
+	for (i = 0; data[i].mask || data[i].val; i++)
+		if (data[i].reg > regmap_config.max_register)
+			regmap_config.max_register = data[i].reg;
+
+	ephy->regmap = devm_regmap_init_mmio(dev, base, &regmap_config);
+	if (IS_ERR(ephy->regmap))
+		return PTR_ERR(ephy->regmap);
+
+	phy = devm_phy_create(dev, dev->of_node, &en75_pcie_phy_ops);
+	if (IS_ERR(phy))
+		return PTR_ERR(phy);
+
+	phy_set_drvdata(phy, ephy);
+
+	provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
+
+	return PTR_ERR_OR_ZERO(provider);
+}
+
+static const struct of_device_id en75_pcie_phy_ids[] = {
+	{ .compatible = "econet,en7528-pcie-gen1", .data = en7528_phy_gen1 },
+	{ .compatible = "econet,en7528-pcie-gen2", .data = en7528_phy_gen2 },
+	{ .compatible = "econet,en751221-pcie-gen1", .data = en7528_phy_gen1 },
+	{ .compatible = "econet,en751221-pcie-gen2", .data = en751221_phy_gen2 },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, en75_pcie_phy_ids);
+
+static struct platform_driver en75_pcie_phy_driver = {
+	.probe = en75_pcie_phy_probe,
+	.driver = {
+		.name = "econet-pcie-phy",
+		.of_match_table = en75_pcie_phy_ids,
+	},
+};
+module_platform_driver(en75_pcie_phy_driver);
+
+MODULE_AUTHOR("Caleb James DeLisle <cjd@cjdns.fr>");
+MODULE_DESCRIPTION("EcoNet PCIe PHY driver");
+MODULE_LICENSE("GPL");