phy: amlogic: Add Amlogic AXG PCIE PHY Driver

This adds support for the PCI PHY found in the Amlogic AXG SoC Family.
This will allow to mutualize code in pci-meson.c between AXG and G12A
SoC.

This PHY also uses and chains an analog PHY, which on AXG platform
is needed to have reliable PCIe communication.

Signed-off-by: Remi Pommarel <[e-mail]>
Signed-off-by: Lorenzo Pieralisi <[e-mail]>
Reviewed-by: Neil Armstrong <[e-mail]>

drivers/phy/amlogic/Kconfig

···
 	  in Meson G12A SoCs.
 	  If unsure, say N.
 
+config PHY_MESON_AXG_PCIE
+	tristate "Meson AXG PCIE PHY driver"
+	default ARCH_MESON
+	depends on OF && (ARCH_MESON || COMPILE_TEST)
+	select GENERIC_PHY
+	select REGMAP_MMIO
+	help
+	  Enable this to support the Meson MIPI + PCIE PHY found
+	  in Meson AXG SoCs.
+	  If unsure, say N.
+
 config PHY_MESON_AXG_MIPI_PCIE_ANALOG
 	tristate "Meson AXG MIPI + PCIE analog PHY driver"
 	default ARCH_MESON

drivers/phy/amlogic/Makefile

···
 obj-$(CONFIG_PHY_MESON_G12A_USB2)		+= phy-meson-g12a-usb2.o
 obj-$(CONFIG_PHY_MESON_GXL_USB3)		+= phy-meson-gxl-usb3.o
 obj-$(CONFIG_PHY_MESON_G12A_USB3_PCIE)		+= phy-meson-g12a-usb3-pcie.o
+obj-$(CONFIG_PHY_MESON_AXG_PCIE)		+= phy-meson-axg-pcie.o
 obj-$(CONFIG_PHY_MESON_AXG_MIPI_PCIE_ANALOG)	+= phy-meson-axg-mipi-pcie-analog.o

drivers/phy/amlogic/phy-meson-axg-pcie.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Amlogic AXG PCIE PHY driver
+ *
+ * Copyright (C) 2020 Remi Pommarel <[e-mail]>
+ */
+#include <linux/module.h>
+#include <linux/phy/phy.h>
+#include <linux/regmap.h>
+#include <linux/reset.h>
+#include <linux/platform_device.h>
+#include <linux/bitfield.h>
+#include <dt-bindings/phy/phy.h>
+
+#define MESON_PCIE_REG0 0x00
+#define		MESON_PCIE_COMMON_CLK	BIT(4)
+#define		MESON_PCIE_PORT_SEL	GENMASK(3, 2)
+#define		MESON_PCIE_CLK		BIT(1)
+#define		MESON_PCIE_POWERDOWN	BIT(0)
+
+#define MESON_PCIE_TWO_X1		FIELD_PREP(MESON_PCIE_PORT_SEL, 0x3)
+#define MESON_PCIE_COMMON_REF_CLK	FIELD_PREP(MESON_PCIE_COMMON_CLK, 0x1)
+#define MESON_PCIE_PHY_INIT		(MESON_PCIE_TWO_X1 |		\
+					 MESON_PCIE_COMMON_REF_CLK)
+#define MESON_PCIE_RESET_DELAY		500
+
+struct phy_axg_pcie_priv {
+	struct phy *phy;
+	struct phy *analog;
+	struct regmap *regmap;
+	struct reset_control *reset;
+};
+
+static const struct regmap_config phy_axg_pcie_regmap_conf = {
+	.reg_bits = 8,
+	.val_bits = 32,
+	.reg_stride = 4,
+	.max_register = MESON_PCIE_REG0,
+};
+
+static int phy_axg_pcie_power_on(struct phy *phy)
+{
+	struct phy_axg_pcie_priv *priv = phy_get_drvdata(phy);
+	int ret;
+
+	ret = phy_power_on(priv->analog);
+	if (ret != 0)
+		return ret;
+
+	regmap_update_bits(priv->regmap, MESON_PCIE_REG0,
+			   MESON_PCIE_POWERDOWN, 0);
+	return 0;
+}
+
+static int phy_axg_pcie_power_off(struct phy *phy)
+{
+	struct phy_axg_pcie_priv *priv = phy_get_drvdata(phy);
+	int ret;
+
+	ret = phy_power_off(priv->analog);
+	if (ret != 0)
+		return ret;
+
+	regmap_update_bits(priv->regmap, MESON_PCIE_REG0,
+			   MESON_PCIE_POWERDOWN, 1);
+	return 0;
+}
+
+static int phy_axg_pcie_init(struct phy *phy)
+{
+	struct phy_axg_pcie_priv *priv = phy_get_drvdata(phy);
+	int ret;
+
+	ret = phy_init(priv->analog);
+	if (ret != 0)
+		return ret;
+
+	regmap_write(priv->regmap, MESON_PCIE_REG0, MESON_PCIE_PHY_INIT);
+	return reset_control_reset(priv->reset);
+}
+
+static int phy_axg_pcie_exit(struct phy *phy)
+{
+	struct phy_axg_pcie_priv *priv = phy_get_drvdata(phy);
+	int ret;
+
+	ret = phy_exit(priv->analog);
+	if (ret != 0)
+		return ret;
+
+	return reset_control_reset(priv->reset);
+}
+
+static int phy_axg_pcie_reset(struct phy *phy)
+{
+	struct phy_axg_pcie_priv *priv = phy_get_drvdata(phy);
+	int ret = 0;
+
+	ret = phy_reset(priv->analog);
+	if (ret != 0)
+		goto out;
+
+	ret = reset_control_assert(priv->reset);
+	if (ret != 0)
+		goto out;
+	udelay(MESON_PCIE_RESET_DELAY);
+
+	ret = reset_control_deassert(priv->reset);
+	if (ret != 0)
+		goto out;
+	udelay(MESON_PCIE_RESET_DELAY);
+
+out:
+	return ret;
+}
+
+static const struct phy_ops phy_axg_pcie_ops = {
+	.init = phy_axg_pcie_init,
+	.exit = phy_axg_pcie_exit,
+	.power_on = phy_axg_pcie_power_on,
+	.power_off = phy_axg_pcie_power_off,
+	.reset = phy_axg_pcie_reset,
+	.owner = THIS_MODULE,
+};
+
+static int phy_axg_pcie_probe(struct platform_device *pdev)
+{
+	struct phy_provider *pphy;
+	struct device *dev = &pdev->dev;
+	struct phy_axg_pcie_priv *priv;
+	struct device_node *np = dev->of_node;
+	struct resource *res;
+	void __iomem *base;
+	int ret;
+
+	priv = devm_kmalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->phy = devm_phy_create(dev, np, &phy_axg_pcie_ops);
+	if (IS_ERR(priv->phy)) {
+		ret = PTR_ERR(priv->phy);
+		if (ret != -EPROBE_DEFER)
+			dev_err(dev, "failed to create PHY\n");
+		return ret;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	priv->regmap = devm_regmap_init_mmio(dev, base,
+					     &phy_axg_pcie_regmap_conf);
+	if (IS_ERR(priv->regmap))
+		return PTR_ERR(priv->regmap);
+
+	priv->reset = devm_reset_control_array_get(dev, false, false);
+	if (IS_ERR(priv->reset))
+		return PTR_ERR(priv->reset);
+
+	priv->analog = devm_phy_get(dev, "analog");
+	if (IS_ERR(priv->analog))
+		return PTR_ERR(priv->analog);
+
+	phy_set_drvdata(priv->phy, priv);
+	dev_set_drvdata(dev, priv);
+	pphy = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
+
+	return PTR_ERR_OR_ZERO(pphy);
+}
+
+static const struct of_device_id phy_axg_pcie_of_match[] = {
+	{
+		.compatible = "amlogic,axg-pcie-phy",
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, phy_axg_pcie_of_match);
+
+static struct platform_driver phy_axg_pcie_driver = {
+	.probe = phy_axg_pcie_probe,
+	.driver = {
+		.name = "phy-axg-pcie",
+		.of_match_table = phy_axg_pcie_of_match,
+	},
+};
+module_platform_driver(phy_axg_pcie_driver);
+
+MODULE_AUTHOR("Remi Pommarel <[e-mail]>");
+MODULE_DESCRIPTION("Amlogic AXG PCIE PHY driver");
+MODULE_LICENSE("GPL v2");