Amlogic Meson8/8b/8m2 SoCs embed a HDMI TX PHY. Unfortunately there is
no (public) documentation for this hardware. The best thing we have is
the 3.10 vendor kernel, which unfortunately doesn't document most
register bits (only a few are named there, the rest is all magic
numbers).
It is possible that this is a TranSwitch HDMI TX PHY based core, but
this is pure speculation.
Adding a driver for the HDMI TX PHY gets us one step closer to video
output on these older SoCs.
Changes since v2 at [1]:
- Use "amlogic,meson8-hdmi-tx-phy" as fallback compatible string for
Meson8b and Meson8m2. This affects both patches in this series and
it's the reason why I dropped Rob's Reviewed-by.
- Add a comment to the driver explaining that there no detailed
register documentation (naming) is available and that's why we also
use some magic values in the driver as suggested by Vinod.
- Hardcode the HHI_HDMI_PHY_CNTL* register offsets (from the HHI area)
directly in the driver instead of using some incomplete "reg" property
parsing code. This also makes it easier to compare the register values
with the vendor kernel sources and datasheets as the offset doesn't
have to be added/subtracted when comparing the values.
Changes since v1 at [0]:
- add a reg property to the dt-bindings
- parse the reg property (register offset) in the driver
- update copyright year to 2021 (spotted by Vinod, thanks!)
- drop "default ARCH_MESON" from the Kconfig entry
[0] https://patchwork.kernel.org/project/linux-amlogic/cover/[email protected]/
[1] https://patchwork.kernel.org/project/linux-amlogic/cover/[email protected]/
Martin Blumenstingl (2):
dt-bindings: phy: Add the Amlogic Meson8 HDMI TX PHY bindings
phy: amlogic: Add a new driver for the HDMI TX PHY on Meson8/8b/8m2
.../phy/amlogic,meson8-hdmi-tx-phy.yaml | 65 +++++++
drivers/phy/amlogic/Kconfig | 10 ++
drivers/phy/amlogic/Makefile | 1 +
drivers/phy/amlogic/phy-meson8-hdmi-tx.c | 160 ++++++++++++++++++
4 files changed, 236 insertions(+)
create mode 100644 Documentation/devicetree/bindings/phy/amlogic,meson8-hdmi-tx-phy.yaml
create mode 100644 drivers/phy/amlogic/phy-meson8-hdmi-tx.c
--
2.33.1
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 <[email protected]>
---
drivers/phy/amlogic/Kconfig | 10 ++
drivers/phy/amlogic/Makefile | 1 +
drivers/phy/amlogic/phy-meson8-hdmi-tx.c | 160 +++++++++++++++++++++++
3 files changed, 171 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..f9a6572c27d8
--- /dev/null
+++ b/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 <[email protected]>
+ */
+
+#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 <[email protected]>");
+MODULE_DESCRIPTION("Meson8, Meson8b and Meson8m2 HDMI TX PHY driver");
+MODULE_LICENSE("GPL v2");
--
2.33.1
On 20-10-21, 21:51, Martin Blumenstingl wrote:
> Amlogic Meson8/8b/8m2 SoCs embed a HDMI TX PHY. Unfortunately there is
> no (public) documentation for this hardware. The best thing we have is
> the 3.10 vendor kernel, which unfortunately doesn't document most
> register bits (only a few are named there, the rest is all magic
> numbers).
> It is possible that this is a TranSwitch HDMI TX PHY based core, but
> this is pure speculation.
>
> Adding a driver for the HDMI TX PHY gets us one step closer to video
> output on these older SoCs.
Applied, thanks
--
~Vinod