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>
---
 drivers/phy/amlogic/Kconfig              |  10 ++
 drivers/phy/amlogic/Makefile             |   1 +
 drivers/phy/amlogic/phy-meson8-hdmi-tx.c | 162 +++++++++++++++++++++++
 3 files changed, 173 insertions(+)
 create mode 100644 drivers/phy/amlogic/phy-meson8-hdmi-tx.c

diff --git a/drivers/phy/amlogic/Kconfig b/drivers/phy/amlogic/Kconfig
index db5d0cd757e3..486ca23aba32 100644
--- a/drivers/phy/amlogic/Kconfig
+++ b/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

diff --git a/drivers/phy/amlogic/Makefile b/drivers/phy/amlogic/Makefile
index 8fa07fbd0d92..c0886c850bb0 100644
--- a/drivers/phy/amlogic/Makefile
+++ b/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

diff --git a/drivers/phy/amlogic/phy-meson8-hdmi-tx.c b/drivers/phy/amlogic/phy-meson8-hdmi-tx.c
new file mode 100644
index 000000000000..ba5a4de54811
--- /dev/null
+++ b/drivers/phy/amlogic/phy-meson8-hdmi-tx.c

@@ -0,0 +1,162 @@
+// 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>
+
+#define HHI_HDMI_PHY_CNTL0				0x0
+	#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				0x4
+	#define HHI_HDMI_PHY_CNTL1_CLOCK_ENABLE		BIT(1)
+	#define HHI_HDMI_PHY_CNTL1_SOFT_RESET		BIT(0)
+
+#define HHI_HDMI_PHY_CNTL2				0x8
+
+struct phy_meson8_hdmi_tx_priv {
+	struct regmap		*hhi;
+	struct clk		*tmds_clk;
+	unsigned int		reg_offset;
+};
+
+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;