[PATCH v2 10/15] drm/bridge: starfive: Add JH7110 HDMI controller driver

[Michal Wilczynski]

Add the HDMI controller (bridge) driver for the StarFive JH7110.

This driver binds to the starfive,jh7110-inno-hdmi-controller node.
It gets its shared regmap from its parent and its clocks (sys, mclk,
bclk) from voutcrg. It consumes the pclk (pixel clock) and PHY from its
hdmi_phy sibling.

The driver calls the generic inno_hdmi_probe function and passes the
shared regmap to it, registering as a DRM bridge. The .enable hook is
responsible for setting the PHY's pixel clock rate via clk_set_rate()
and powering on the PHY via phy_power_on().

The PHY can only generate the discrete set of pixel clocks described by
its pre-PLL table, so .mode_valid rejects any mode clk_round_rate()
cannot satisfy. Without it such a mode would be advertised to userspace
and the modeset would appear to succeed while the display stayed blank.

.enable returns early when the rate is unsupported or the PHY fails to
power on, so track whether the pixel clock was actually enabled and let
.disable tear down only what was brought up, otherwise the clock
refcount underflows.

Signed-off-by: Michal Wilczynski <m.wilczynski@xxxxxxxxxxx>
---
 drivers/gpu/drm/bridge/Kconfig            |  11 ++
 drivers/gpu/drm/bridge/Makefile           |   1 +
 drivers/gpu/drm/bridge/jh7110-inno-hdmi.c | 224 ++++++++++++++++++++++++++++++
 3 files changed, 236 insertions(+)

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index 4a57d49b4c6d3ab4b965228835b372d191647197..75b1cf6727d5a32310dcf9fe5734d95e14eea8fe 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -359,6 +359,17 @@ config DRM_SOLOMON_SSD2825
 	  Say M here if you want to support this hardware as a module.
 	  The module will be named "ssd2825".
 
+config DRM_STARFIVE_JH7110_INNO_HDMI
+	tristate "Starfive JH7110 Innosilicon HDMI bridge"
+	depends on OF
+	depends on ARCH_STARFIVE || COMPILE_TEST
+	select DRM_INNO_HDMI
+	help
+	  Enable support for the StarFive JH7110 specific implementation
+	  of the Innosilicon HDMI controller.
+	  This driver acts as a glue layer between the JH7110 HDMI subsystem
+	  parent driver and the generic Innosilicon HDMI bridge driver.
+
 config DRM_THINE_THC63LVD1024
 	tristate "Thine THC63LVD1024 LVDS decoder bridge"
 	depends on OF
diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
index 15cc821d85b7ea6f3cdc313f3e521b028de567d7..5d843f4ad7ed50b28cb75286c5e22789d91a0836 100644
--- a/drivers/gpu/drm/bridge/Makefile
+++ b/drivers/gpu/drm/bridge/Makefile
@@ -30,6 +30,7 @@ obj-$(CONFIG_DRM_SIL_SII8620) += sil-sii8620.o
 obj-$(CONFIG_DRM_SII902X) += sii902x.o
 obj-$(CONFIG_DRM_SII9234) += sii9234.o
 obj-$(CONFIG_DRM_SIMPLE_BRIDGE) += simple-bridge.o
+obj-$(CONFIG_DRM_STARFIVE_JH7110_INNO_HDMI) += jh7110-inno-hdmi.o
 obj-$(CONFIG_DRM_SOLOMON_SSD2825) += ssd2825.o
 obj-$(CONFIG_DRM_THEAD_TH1520_DW_HDMI) += th1520-dw-hdmi.o
 obj-$(CONFIG_DRM_THINE_THC63LVD1024) += thc63lvd1024.o
diff --git a/drivers/gpu/drm/bridge/jh7110-inno-hdmi.c b/drivers/gpu/drm/bridge/jh7110-inno-hdmi.c
new file mode 100644
index 0000000000000000000000000000000000000000..be865aa39e33f70614fa7cb58a683b9fcf051599
--- /dev/null
+++ b/drivers/gpu/drm/bridge/jh7110-inno-hdmi.c
@@ -0,0 +1,224 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) StarFive Technology Co., Ltd.
+ * Copyright (c) 2025 Samsung Electronics Co., Ltd.
+ * Author: Michal Wilczynski <m.wilczynski@xxxxxxxxxxx>
+ *
+ * HDMI controller (bridge) driver for the StarFive JH7110 HDMI subsystem.
+ */
+
+#include <linux/clk.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/phy/phy.h>
+#include <linux/regmap.h>
+#include <linux/reset.h>
+
+#include <drm/bridge/inno_hdmi.h>
+#include <drm/drm_modes.h>
+
+enum stf_hdmi_ctrl_clocks { CLK_SYS = 0, CLK_M, CLK_B, CLK_PCLK, CLK_CTRL_NUM };
+
+struct stf_inno_hdmi_controller {
+	struct device *dev;
+	struct clk_bulk_data clks[CLK_CTRL_NUM];
+	struct reset_control *tx_rst;
+	struct phy *phy;
+	bool enabled;
+};
+
+static enum drm_mode_status
+inno_hdmi_starfive_mode_valid(struct device *dev,
+			      const struct drm_display_mode *mode)
+{
+	struct stf_inno_hdmi_controller *ctrl = dev_get_drvdata(dev);
+	unsigned long pixelclk = mode->clock * 1000;
+	long rounded;
+
+	/*
+	 * The PHY can only generate the discrete set of pixel clocks described
+	 * by its pre-PLL table, and clk_round_rate() fails for anything else.
+	 * Reject those modes here: without this the modeset would appear to
+	 * succeed while the PHY never produces a signal.
+	 */
+	rounded = clk_round_rate(ctrl->clks[CLK_PCLK].clk, pixelclk);
+	if (rounded < 0 || rounded != pixelclk)
+		return MODE_NOCLOCK;
+
+	return MODE_OK;
+}
+
+static void inno_hdmi_starfive_enable(struct device *dev,
+				      struct drm_display_mode *mode)
+{
+	struct stf_inno_hdmi_controller *ctrl = dev_get_drvdata(dev);
+	int ret;
+
+	/*
+	 * 1. Set the pixel clock rate. This calls the PHY driver's .set_rate op.
+	 */
+	ret = clk_set_rate(ctrl->clks[CLK_PCLK].clk, mode->clock * 1000);
+	if (ret) {
+		dev_err(dev, "Failed to set pclk rate %d: %d\n",
+			mode->clock * 1000, ret);
+		return;
+	}
+
+	/*
+	 * 2. Enable the pixel clock. This calls the PHY driver's .prepare op.
+	 */
+	ret = clk_prepare_enable(ctrl->clks[CLK_PCLK].clk);
+	if (ret) {
+		dev_err(dev, "Failed to enable pclk: %d\n", ret);
+		return;
+	}
+
+	/*
+	 * 3. Power on the PHY. This calls the PHY driver's .power_on op,
+	 * which configures the Post-PLL and analog blocks.
+	 */
+	ret = phy_power_on(ctrl->phy);
+	if (ret) {
+		dev_err(dev, "Failed to power on PHY: %d\n", ret);
+		clk_disable_unprepare(ctrl->clks[CLK_PCLK].clk);
+		return;
+	}
+
+	ctrl->enabled = true;
+}
+
+static void inno_hdmi_starfive_disable(struct device *dev)
+{
+	struct stf_inno_hdmi_controller *ctrl = dev_get_drvdata(dev);
+
+	/*
+	 * .enable bails out early if the pixel clock rate is unsupported or
+	 * the PHY fails to power on, leaving pclk and the PHY untouched.
+	 * Only tear down what was actually brought up, otherwise the clock
+	 * refcount underflows.
+	 */
+	if (!ctrl->enabled)
+		return;
+
+	phy_power_off(ctrl->phy);
+	clk_disable_unprepare(ctrl->clks[CLK_PCLK].clk);
+	ctrl->enabled = false;
+}
+
+static int starfive_inno_hdmi_controller_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device *parent = dev->parent;
+	struct stf_inno_hdmi_controller *ctrl;
+	const struct inno_hdmi_plat_data *plat_data;
+	struct regmap *regmap;
+	struct inno_hdmi *inno;
+	int ret;
+
+	ctrl = devm_kzalloc(dev, sizeof(*ctrl), GFP_KERNEL);
+	if (!ctrl)
+		return -ENOMEM;
+
+	ctrl->dev = dev;
+	platform_set_drvdata(pdev, ctrl);
+
+	/* Get the shared regmap from the parent */
+	regmap = dev_get_regmap(parent, NULL);
+	if (!regmap) {
+		dev_err(dev, "Failed to get parent regmap\n");
+		return -ENODEV;
+	}
+
+	ctrl->phy = devm_phy_get(dev, "hdmi-phy");
+	if (IS_ERR(ctrl->phy))
+		return dev_err_probe(dev, PTR_ERR(ctrl->phy), "Failed to get PHY\n");
+
+	ctrl->tx_rst = devm_reset_control_get_exclusive(dev, "hdmi_tx");
+	if (IS_ERR(ctrl->tx_rst))
+		return dev_err_probe(dev, PTR_ERR(ctrl->tx_rst), "failed to get tx reset\n");
+
+	/* Populate the clock names this controller *consumes* */
+	ctrl->clks[CLK_SYS].id = "sys";
+	ctrl->clks[CLK_M].id = "mclk";
+	ctrl->clks[CLK_B].id = "bclk";
+	ctrl->clks[CLK_PCLK].id = "pclk"; /* Pixel clock *from* PHY */
+
+	ret = devm_clk_bulk_get(dev, CLK_CTRL_NUM, ctrl->clks);
+	if (ret)
+		return dev_err_probe(dev, ret, "Unable to get controller clocks\n");
+
+	/* pclk is enabled on demand during modeset */
+	ret = clk_bulk_prepare_enable(CLK_CTRL_NUM - 1, ctrl->clks);
+	if (ret)
+		return ret;
+
+	ret = reset_control_deassert(ctrl->tx_rst);
+	if (ret) {
+		clk_bulk_disable_unprepare(CLK_CTRL_NUM - 1, ctrl->clks);
+		return ret;
+	}
+
+	plat_data = of_device_get_match_data(dev);
+
+	/* Hand off to the generic library to create the bridge. */
+	inno = inno_hdmi_probe(pdev, plat_data);
+	if (IS_ERR(inno)) {
+		reset_control_assert(ctrl->tx_rst);
+		clk_bulk_disable_unprepare(CLK_CTRL_NUM - 1, ctrl->clks);
+		return PTR_ERR(inno);
+	}
+
+	return 0;
+}
+
+static void starfive_inno_hdmi_controller_remove(struct platform_device *pdev)
+{
+	struct stf_inno_hdmi_controller *ctrl = platform_get_drvdata(pdev);
+
+	reset_control_assert(ctrl->tx_rst);
+	clk_bulk_disable_unprepare(CLK_CTRL_NUM - 1, ctrl->clks);
+}
+
+/*
+ * This table is now only used for the generic .mode_valid check.
+ * The real validation happens in the PHY driver's .round_rate.
+ */
+static struct inno_hdmi_phy_config stf_hdmi_phy_configs[] = {
+	{ 297000000, 0x00, 0x00 },
+	{ ~0UL, 0x00, 0x00 }, /* Sentinel */
+};
+
+static const struct inno_hdmi_plat_ops stf_inno_hdmi_plat_ops = {
+	.enable = inno_hdmi_starfive_enable,
+	.disable = inno_hdmi_starfive_disable,
+	.mode_valid = inno_hdmi_starfive_mode_valid,
+};
+
+static const struct inno_hdmi_plat_data stf_inno_hdmi_plat_data = {
+	.ops = &stf_inno_hdmi_plat_ops,
+	.phy_configs = stf_hdmi_phy_configs,
+	.default_phy_config = &stf_hdmi_phy_configs[0],
+};
+
+static const struct of_device_id starfive_hdmi_controller_dt_ids[] = {
+	{ .compatible = "starfive,jh7110-inno-hdmi-controller",
+	  .data = &stf_inno_hdmi_plat_data },
+	{}
+};
+MODULE_DEVICE_TABLE(of, starfive_hdmi_controller_dt_ids);
+
+struct platform_driver starfive_inno_hdmi_controller_driver = {
+	.probe = starfive_inno_hdmi_controller_probe,
+	.remove = starfive_inno_hdmi_controller_remove,
+	.driver = {
+		.name = "starfive-inno-hdmi-controller",
+		.of_match_table = starfive_hdmi_controller_dt_ids,
+	},
+};
+module_platform_driver(starfive_inno_hdmi_controller_driver);
+
+MODULE_AUTHOR("Michal Wilczynski <m.wilczynski@xxxxxxxxxxx>");
+MODULE_DESCRIPTION("StarFive INNO HDMI Controller Driver");
+MODULE_LICENSE("GPL");

-- 
2.34.1