[PATCH v3 5/9] drm/bridge: add a driver for T-Head TH1520 HDMI controller

Icenowy Zheng
2025-11-24T10:54:08Z

T-Head TH1520 SoC contains a Synopsys DesignWare HDMI controller (paired
with DesignWare HDMI TX PHY Gen2) that takes the "DP" output from the
display controller.

Add a driver for this controller utilizing the common DesignWare HDMI
code in the kernel.

Signed-off-by: Icenowy Zheng <uwu@icenowy.me>
---
No changes in v3.

Changes in v2:
- Created a new function to set PHY parameters and refactored the
control flow of the configure_phy callback.

MAINTAINERS | 1 +
drivers/gpu/drm/bridge/Kconfig | 10 ++
drivers/gpu/drm/bridge/Makefile | 1 +
drivers/gpu/drm/bridge/th1520-dw-hdmi.c | 173 ++++++++++++++++++++++++
4 files changed, 185 insertions(+)
create mode 100644 drivers/gpu/drm/bridge/th1520-dw-hdmi.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 46126ce2f968e..32715100a1e10 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22175,6 +22175,7 @@ F: Documentation/devicetree/bindings/reset/thead,th1520-reset.yaml
F: arch/riscv/boot/dts/thead/
F: drivers/clk/thead/clk-th1520-ap.c
F: drivers/firmware/thead,th1520-aon.c
+F: drivers/gpu/drm/bridge/th1520-dw-hdmi.c
F: drivers/mailbox/mailbox-th1520.c
F: drivers/net/ethernet/stmicro/stmmac/dwmac-thead.c
F: drivers/pinctrl/pinctrl-th1520.c
diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index a250afd8d6622..8e19f5fb9ad7c 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -335,6 +335,16 @@ config DRM_THINE_THC63LVD1024
help
Thine THC63LVD1024 LVDS/parallel converter driver.

+config DRM_THEAD_TH1520_DW_HDMI
+ tristate "T-Head TH1520 DesignWare HDMI bridge"
+ depends on OF
+ depends on COMMON_CLK
+ depends on ARCH_THEAD || COMPILE_TEST
+ select DRM_DW_HDMI
+ help
+ Choose this to enable support for the internal HDMI bridge found
+ on the T-Head TH1520 SoC.
+
config DRM_TOSHIBA_TC358762
tristate "TC358762 DSI/DPI bridge"
depends on OF
diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
index c7dc03182e592..085b5db45d6fd 100644
--- a/drivers/gpu/drm/bridge/Makefile
+++ b/drivers/gpu/drm/bridge/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_DRM_SII902X) += sii902x.o
obj-$(CONFIG_DRM_SII9234) += sii9234.o
obj-$(CONFIG_DRM_SIMPLE_BRIDGE) += simple-bridge.o
obj-$(CONFIG_DRM_SOLOMON_SSD2825) += ssd2825.o
+obj-$(CONFIG_DRM_THEAD_TH1520_DW_HDMI) += th1520-dw-hdmi.o
obj-$(CONFIG_DRM_THINE_THC63LVD1024) += thc63lvd1024.o
obj-$(CONFIG_DRM_TOSHIBA_TC358762) += tc358762.o
obj-$(CONFIG_DRM_TOSHIBA_TC358764) += tc358764.o
diff --git a/drivers/gpu/drm/bridge/th1520-dw-hdmi.c b/drivers/gpu/drm/bridge/th1520-dw-hdmi.c
new file mode 100644
index 0000000000000..389eead5f1c45
--- /dev/null
+++ b/drivers/gpu/drm/bridge/th1520-dw-hdmi.c
@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2025 Icenowy Zheng <uwu@icenowy.me>
+ *
+ * Based on rcar_dw_hdmi.c, which is:
+ * Copyright (C) 2016 Renesas Electronics Corporation
+ * Based on imx8mp-hdmi-tx.c, which is:
+ * Copyright (C) 2022 Pengutronix, Lucas Stach <kernel@pengutronix.de>
+ */
+
+#include <linux/clk.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+
+#include <drm/bridge/dw_hdmi.h>
+#include <drm/drm_modes.h>
+
+#define TH1520_HDMI_PHY_OPMODE_PLLCFG 0x06 /* Mode of operation and PLL dividers */
+#define TH1520_HDMI_PHY_CKSYMTXCTRL 0x09 /* Clock Symbol and Transmitter Control Register */
+#define TH1520_HDMI_PHY_VLEVCTRL 0x0e /* Voltage Level Control Register */
+#define TH1520_HDMI_PHY_PLLCURRGMPCTRL 0x10 /* PLL current and Gmp (conductance) */
+#define TH1520_HDMI_PHY_PLLDIVCTRL 0x11 /* PLL dividers */
+#define TH1520_HDMI_PHY_TXTERM 0x19 /* Transmission Termination Register */
+
+struct th1520_hdmi_phy_params {
+ unsigned long mpixelclock;
+ u16 opmode_pllcfg;
+ u16 pllcurrgmpctrl;
+ u16 plldivctrl;
+ u16 cksymtxctrl;
+ u16 vlevctrl;
+ u16 txterm;
+};
+
+static const struct th1520_hdmi_phy_params th1520_hdmi_phy_params[] = {
+ { 35500000, 0x0003, 0x0283, 0x0628, 0x8088, 0x01a0, 0x0007 },
+ { 44900000, 0x0003, 0x0285, 0x0228, 0x8088, 0x01a0, 0x0007 },
+ { 71000000, 0x0002, 0x1183, 0x0614, 0x8088, 0x01a0, 0x0007 },
+ { 90000000, 0x0002, 0x1142, 0x0214, 0x8088, 0x01a0, 0x0007 },
+ { 121750000, 0x0001, 0x20c0, 0x060a, 0x8088, 0x01a0, 0x0007 },
+ { 165000000, 0x0001, 0x2080, 0x020a, 0x8088, 0x01a0, 0x0007 },
+ { 198000000, 0x0000, 0x3040, 0x0605, 0x83c8, 0x0120, 0x0004 },
+ { 297000000, 0x0000, 0x3041, 0x0205, 0x81dc, 0x0200, 0x0005 },
+ { 371250000, 0x0640, 0x3041, 0x0205, 0x80f6, 0x0140, 0x0000 },
+ { 495000000, 0x0640, 0x3080, 0x0005, 0x80f6, 0x0140, 0x0000 },
+ { 594000000, 0x0640, 0x3080, 0x0005, 0x80fa, 0x01e0, 0x0004 },
+};
+
+struct th1520_hdmi {
+ struct dw_hdmi_plat_data plat_data;
+ struct dw_hdmi *dw_hdmi;
+ struct clk *pixclk;
+ struct reset_control *mainrst, *prst;
+};
+
+static enum drm_mode_status
+th1520_hdmi_mode_valid(struct dw_hdmi *hdmi, void *data,
+ const struct drm_display_info *info,
+ const struct drm_display_mode *mode)
+{
+ /*
+ * The maximum supported clock frequency is 594 MHz, as shown in the PHY
+ * parameters table.
+ */
+ if (mode->clock > 594000)
+ return MODE_CLOCK_HIGH;
+
+ return MODE_OK;
+}
+
+static void th1520_hdmi_phy_set_params(struct dw_hdmi *hdmi,
+ const struct th1520_hdmi_phy_params *params)
+{
+ dw_hdmi_phy_i2c_write(hdmi, params->opmode_pllcfg,
+ TH1520_HDMI_PHY_OPMODE_PLLCFG);
+ dw_hdmi_phy_i2c_write(hdmi, params->pllcurrgmpctrl,
+ TH1520_HDMI_PHY_PLLCURRGMPCTRL);
+ dw_hdmi_phy_i2c_write(hdmi, params->plldivctrl,
+ TH1520_HDMI_PHY_PLLDIVCTRL);
+ dw_hdmi_phy_i2c_write(hdmi, params->vlevctrl,
+ TH1520_HDMI_PHY_VLEVCTRL);
+ dw_hdmi_phy_i2c_write(hdmi, params->cksymtxctrl,
+ TH1520_HDMI_PHY_CKSYMTXCTRL);
+ dw_hdmi_phy_i2c_write(hdmi, params->txterm,
+ TH1520_HDMI_PHY_TXTERM);
+}
+
+static int th1520_hdmi_phy_configure(struct dw_hdmi *hdmi, void *data,
+ unsigned long mpixelclock)
+{
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(th1520_hdmi_phy_params); i++) {
+ if (mpixelclock <= th1520_hdmi_phy_params[i].mpixelclock) {
+ th1520_hdmi_phy_set_params(hdmi,
+ &th1520_hdmi_phy_params[i]);
+ return 0;
+ }
+ }
+
+ return -EINVAL;
+}
+
+static int th1520_dw_hdmi_probe(struct platform_device *pdev)
+{
+ struct th1520_hdmi *hdmi;
+ struct dw_hdmi_plat_data *plat_data;
+ struct device *dev = &pdev->dev;
+
+ hdmi = devm_kzalloc(dev, sizeof(*hdmi), GFP_KERNEL);
+ if (!hdmi)
+ return -ENOMEM;
+
+ plat_data = &hdmi->plat_data;
+
+ hdmi->pixclk = devm_clk_get_enabled(dev, "pix");
+ if (IS_ERR(hdmi->pixclk))
+ return dev_err_probe(dev, PTR_ERR(hdmi->pixclk),
+ "Unable to get pixel clock\n");
+
+ hdmi->mainrst = devm_reset_control_get_exclusive_deasserted(dev, "main");
+ if (IS_ERR(hdmi->mainrst))
+ return dev_err_probe(dev, PTR_ERR(hdmi->mainrst),
+ "Unable to get main reset\n");
+
+ hdmi->prst = devm_reset_control_get_exclusive_deasserted(dev, "apb");
+ if (IS_ERR(hdmi->prst))
+ return dev_err_probe(dev, PTR_ERR(hdmi->prst),
+ "Unable to get apb reset\n");
+
+ plat_data->output_port = 1;
+ plat_data->mode_valid = th1520_hdmi_mode_valid;
+ plat_data->configure_phy = th1520_hdmi_phy_configure;
+ plat_data->priv_data = hdmi;
+
+ hdmi->dw_hdmi = dw_hdmi_probe(pdev, plat_data);
+ if (IS_ERR(hdmi))
+ return PTR_ERR(hdmi);
+
+ platform_set_drvdata(pdev, hdmi);
+
+ return 0;
+}
+
+static void th1520_dw_hdmi_remove(struct platform_device *pdev)
+{
+ struct dw_hdmi *hdmi = platform_get_drvdata(pdev);
+
+ dw_hdmi_remove(hdmi);
+}
+
+static const struct of_device_id th1520_dw_hdmi_of_table[] = {
+ { .compatible = "thead,th1520-dw-hdmi" },
+ { /* Sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, th1520_dw_hdmi_of_table);
+
+static struct platform_driver th1520_dw_hdmi_platform_driver = {
+ .probe = th1520_dw_hdmi_probe,
+ .remove = th1520_dw_hdmi_remove,
+ .driver = {
+ .name = "th1520-dw-hdmi",
+ .of_match_table = th1520_dw_hdmi_of_table,
+ },
+};
+
+module_platform_driver(th1520_dw_hdmi_platform_driver);
+
+MODULE_AUTHOR("Icenowy Zheng <uwu@icenowy.me>");
+MODULE_DESCRIPTION("T-Head TH1520 HDMI Encoder Driver");
+MODULE_LICENSE("GPL");
--
2.52.0