phy: amlogic: Add a new driver for the HDMI TX PHY on Meson8/8b/8m2

Amlogic Meson8/8b/8m2 have a built-in HDMI PHY in the HHI register
region. Unfortunately only few register bits are documented. For
HHI_HDMI_PHY_CNTL0 the magic numbers are taken from the 3.10 vendor
kernel.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/20211020195107.1564533-3-martin.blumenstingl@googlemail.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/phy/amlogic/Kconfig

@@ -2,6 +2,16 @@
 #
 # Phy drivers for Amlogic platforms
 #
+config PHY_MESON8_HDMI_TX
+	tristate "Meson8, Meson8b and Meson8m2 HDMI TX PHY driver"
+	depends on (ARCH_MESON && ARM) || COMPILE_TEST
+	depends on OF
+	select MFD_SYSCON
+	help
+	  Enable this to support the HDMI TX PHYs found in Meson8,
+	  Meson8b and Meson8m2 SoCs.
+	  If unsure, say N.
+
 config PHY_MESON8B_USB2
 	tristate "Meson8, Meson8b, Meson8m2 and GXBB USB2 PHY driver"
 	default ARCH_MESON

drivers/phy/amlogic/Makefile

@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_PHY_MESON8_HDMI_TX)		+= phy-meson8-hdmi-tx.o
 obj-$(CONFIG_PHY_MESON8B_USB2)			+= phy-meson8b-usb2.o
 obj-$(CONFIG_PHY_MESON_GXL_USB2)		+= phy-meson-gxl-usb2.o
 obj-$(CONFIG_PHY_MESON_G12A_USB2)		+= phy-meson-g12a-usb2.o

drivers/phy/amlogic/phy-meson8-hdmi-tx.c

@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Meson8, Meson8b and Meson8m2 HDMI TX PHY.
+ *
+ * Copyright (C) 2021 Martin Blumenstingl <martin.blumenstingl@googlemail.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+/*
+ * Unfortunately there is no detailed documentation available for the
+ * HHI_HDMI_PHY_CNTL0 register. CTL0 and CTL1 is all we know about.
+ * Magic register values in the driver below are taken from the vendor
+ * BSP / kernel.
+ */
+#define HHI_HDMI_PHY_CNTL0				0x3a0
+	#define HHI_HDMI_PHY_CNTL0_HDMI_CTL1		GENMASK(31, 16)
+	#define HHI_HDMI_PHY_CNTL0_HDMI_CTL0		GENMASK(15, 0)
+
+#define HHI_HDMI_PHY_CNTL1				0x3a4
+	#define HHI_HDMI_PHY_CNTL1_CLOCK_ENABLE		BIT(1)
+	#define HHI_HDMI_PHY_CNTL1_SOFT_RESET		BIT(0)
+
+#define HHI_HDMI_PHY_CNTL2				0x3a8
+
+struct phy_meson8_hdmi_tx_priv {
+	struct regmap		*hhi;
+	struct clk		*tmds_clk;
+};
+
+static int phy_meson8_hdmi_tx_init(struct phy *phy)
+{
+	struct phy_meson8_hdmi_tx_priv *priv = phy_get_drvdata(phy);
+
+	return clk_prepare_enable(priv->tmds_clk);
+}
+
+static int phy_meson8_hdmi_tx_exit(struct phy *phy)
+{
+	struct phy_meson8_hdmi_tx_priv *priv = phy_get_drvdata(phy);
+
+	clk_disable_unprepare(priv->tmds_clk);
+
+	return 0;
+}
+
+static int phy_meson8_hdmi_tx_power_on(struct phy *phy)
+{
+	struct phy_meson8_hdmi_tx_priv *priv = phy_get_drvdata(phy);
+	unsigned int i;
+	u16 hdmi_ctl0;
+
+	if (clk_get_rate(priv->tmds_clk) >= 2970UL * 1000 * 1000)
+		hdmi_ctl0 = 0x1e8b;
+	else
+		hdmi_ctl0 = 0x4d0b;
+
+	regmap_write(priv->hhi, HHI_HDMI_PHY_CNTL0,
+		     FIELD_PREP(HHI_HDMI_PHY_CNTL0_HDMI_CTL1, 0x08c3) |
+		     FIELD_PREP(HHI_HDMI_PHY_CNTL0_HDMI_CTL0, hdmi_ctl0));
+
+	regmap_write(priv->hhi, HHI_HDMI_PHY_CNTL1, 0x0);
+
+	/* Reset three times, just like the vendor driver does */
+	for (i = 0; i < 3; i++) {
+		regmap_write(priv->hhi, HHI_HDMI_PHY_CNTL1,
+			     HHI_HDMI_PHY_CNTL1_CLOCK_ENABLE |
+			     HHI_HDMI_PHY_CNTL1_SOFT_RESET);
+		usleep_range(1000, 2000);
+
+		regmap_write(priv->hhi, HHI_HDMI_PHY_CNTL1,
+			     HHI_HDMI_PHY_CNTL1_CLOCK_ENABLE);
+		usleep_range(1000, 2000);
+	}
+
+	return 0;
+}
+
+static int phy_meson8_hdmi_tx_power_off(struct phy *phy)
+{
+	struct phy_meson8_hdmi_tx_priv *priv = phy_get_drvdata(phy);
+
+	regmap_write(priv->hhi, HHI_HDMI_PHY_CNTL0,
+		     FIELD_PREP(HHI_HDMI_PHY_CNTL0_HDMI_CTL1, 0x0841) |
+		     FIELD_PREP(HHI_HDMI_PHY_CNTL0_HDMI_CTL0, 0x8d00));
+
+	return 0;
+}
+
+static const struct phy_ops phy_meson8_hdmi_tx_ops = {
+	.init		= phy_meson8_hdmi_tx_init,
+	.exit		= phy_meson8_hdmi_tx_exit,
+	.power_on	= phy_meson8_hdmi_tx_power_on,
+	.power_off	= phy_meson8_hdmi_tx_power_off,
+	.owner		= THIS_MODULE,
+};
+
+static int phy_meson8_hdmi_tx_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct phy_meson8_hdmi_tx_priv *priv;
+	struct phy_provider *phy_provider;
+	struct resource *res;
+	struct phy *phy;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->hhi = syscon_node_to_regmap(np->parent);
+	if (IS_ERR(priv->hhi))
+		return PTR_ERR(priv->hhi);
+
+	priv->tmds_clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(priv->tmds_clk))
+		return PTR_ERR(priv->tmds_clk);
+
+	phy = devm_phy_create(&pdev->dev, np, &phy_meson8_hdmi_tx_ops);
+	if (IS_ERR(phy))
+		return PTR_ERR(phy);
+
+	phy_set_drvdata(phy, priv);
+
+	phy_provider = devm_of_phy_provider_register(&pdev->dev,
+						     of_phy_simple_xlate);
+
+	return PTR_ERR_OR_ZERO(phy_provider);
+}
+
+static const struct of_device_id phy_meson8_hdmi_tx_of_match[] = {
+	{ .compatible = "amlogic,meson8-hdmi-tx-phy" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, phy_meson8_hdmi_tx_of_match);
+
+static struct platform_driver phy_meson8_hdmi_tx_driver = {
+	.probe	= phy_meson8_hdmi_tx_probe,
+	.driver	= {
+		.name		= "phy-meson8-hdmi-tx",
+		.of_match_table	= phy_meson8_hdmi_tx_of_match,
+	},
+};
+module_platform_driver(phy_meson8_hdmi_tx_driver);
+
+MODULE_AUTHOR("Martin Blumenstingl <martin.blumenstingl@googlemail.com>");
+MODULE_DESCRIPTION("Meson8, Meson8b and Meson8m2 HDMI TX PHY driver");
+MODULE_LICENSE("GPL v2");