recipes-kernel/linux/files/0025-bus-Add-Aspeed-LTPI-bus-controller-driver.patch

From 00eba48c2b17c333a23ac60c9d4f686a8da9467c Mon Sep 17 00:00:00 2001
From: Alan Hung <yung-sheng.huang@fii-na.corp-partner.google.com>
Date: Thu, 17 Jul 2025 13:44:01 +0800
Subject: [PATCH] bus: Add Aspeed LTPI bus controller driver

Add Aspeed LTPI bus controller driver to ungate the LTPI clock.
This is base on aspeed SDK 9.07.

Source:
AspeedTech-BMC github:
https://github.com/AspeedTech-BMC/linux/blob/aspeed-master-v6.6/
(cherry picked from commit v00.06.07)

Signed-off-by: Alan Hung <yung-sheng.huang@fii-na.corp-partner.google.com>
---
 drivers/bus/Kconfig       |   7 ++
 drivers/bus/Makefile      |   1 +
 drivers/bus/aspeed-ltpi.c | 215 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 223 insertions(+)
 create mode 100644 drivers/bus/aspeed-ltpi.c

diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index fab27506d..c90fbb50d 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -251,6 +251,13 @@ config DA8XX_MSTPRI
 	  configuration. Allows to adjust the priorities of all master
 	  peripherals.
 
+config ASPEED_LTPI
+	bool "Aspeed LTPI bus controller driver"
+	depends on ARCH_ASPEED
+	help
+	  LVDS Tunneling Protocol and Interface (LTPI) bus controller
+
+
 source "drivers/bus/fsl-mc/Kconfig"
 source "drivers/bus/mhi/Kconfig"
 
diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
index d90eed189..a9030ecee 100644
--- a/drivers/bus/Makefile
+++ b/drivers/bus/Makefile
@@ -38,6 +38,7 @@ obj-$(CONFIG_UNIPHIER_SYSTEM_BUS)	+= uniphier-system-bus.o
 obj-$(CONFIG_VEXPRESS_CONFIG)	+= vexpress-config.o
 
 obj-$(CONFIG_DA8XX_MSTPRI)	+= da8xx-mstpri.o
+obj-$(CONFIG_ASPEED_LTPI)	+= aspeed-ltpi.o
 
 # MHI
 obj-y				+= mhi/
diff --git a/drivers/bus/aspeed-ltpi.c b/drivers/bus/aspeed-ltpi.c
new file mode 100644
index 000000000..6630ee4bd
--- /dev/null
+++ b/drivers/bus/aspeed-ltpi.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+// Copyright ASPEED Technology
+
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/clk.h>
+#include <linux/reset.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+#include <asm/io.h>
+
+#define LTPI_AUTO_CAP_LOW			0x24
+#define   LTPI_I2C_IO_FRAME_EN			GENMASK(29, 24)
+#define LTPI_AUTO_CAP_HIGH			0x28
+
+#define LTPI_LINK_CONTROLL			0x80
+#define   LTPI_AUTO_CONFIG			BIT(10)
+
+#define LTPI_INTR_STATUS			0x100
+#define LTPI_INTR_EN				0x104
+#define   LTPI_INTR_EN_OP_LINK_LOST		BIT(4)
+#define LTPI_LINK_MANAGE_ST			0x108
+#define   LTPI_LINK_PARTNER_FLAG		BIT(24)
+
+#define LTPI_MANUAL_CAP_LOW			0x118
+#define LTPI_MANUAL_CAP_HIGH			0x11c
+
+#define SCU_IO_PINS_TRAP1			0x10
+#define SCU_IO_PINS_TRAP1_CLEAR			0x14
+#define   SCU_IO_PINS_TRAP_LTPI			GENMASK(2, 0)
+#define SCU_IO_OTP_TRAP1			0xa00
+#define SCU_IO_OTP_TRAP1_CLEAR			0xa04
+#define SCU_IO_OTP_TRAP2			0xa20
+#define SCU_IO_OTP_TRAP2_CLEAR			0xa24
+
+#define MAX_I2C_IN_LTPI				6
+
+struct aspeed_ltpi_priv {
+	struct device *dev;
+	void __iomem *regs;
+	struct clk *ltpi_clk;
+	struct clk *ltpi_phyclk;
+	struct reset_control *ltpi_rst;
+	struct regmap *scu;
+	u32 i2c_tunneling;
+};
+
+static irqreturn_t aspeed_ltpi_irq_handler(int irq, void *dev_id)
+{
+	struct aspeed_ltpi_priv *priv = dev_id;
+	u32 status = readl(priv->regs + LTPI_INTR_STATUS);
+
+	if (status & LTPI_INTR_EN_OP_LINK_LOST) {
+		writel(0, priv->regs + LTPI_INTR_EN);
+		writel(status, priv->regs + LTPI_INTR_STATUS);
+		panic("LTPI link lost!\n");
+		/* Will not return */
+	}
+
+	writel(status, priv->regs + LTPI_INTR_STATUS);
+
+	return IRQ_HANDLED;
+}
+
+static int aspeed_ltpi_init_mux(struct aspeed_ltpi_priv *priv)
+{
+	u32 reg, i2c_en;
+
+	reg = readl(priv->regs + LTPI_AUTO_CAP_LOW);
+
+	i2c_en = FIELD_GET(LTPI_I2C_IO_FRAME_EN, reg);
+	i2c_en &= priv->i2c_tunneling;
+
+	reg &= ~LTPI_I2C_IO_FRAME_EN;
+	reg |= FIELD_PREP(LTPI_I2C_IO_FRAME_EN, i2c_en);
+	writel(reg, priv->regs + LTPI_MANUAL_CAP_LOW);
+
+	reg = readl(priv->regs + LTPI_AUTO_CAP_HIGH);
+	writel(reg, priv->regs + LTPI_MANUAL_CAP_HIGH);
+
+	/* Apply LTPI manual configuration */
+	reg = readl(priv->regs + LTPI_LINK_CONTROLL);
+	reg &= ~LTPI_AUTO_CONFIG;
+	writel(reg, priv->regs + LTPI_LINK_CONTROLL);
+
+	return 0;
+}
+
+static int aspeed_ltpi_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct of_dev_auxdata *lookup = dev_get_platdata(dev);
+	struct device_node *np = dev->of_node;
+	const struct of_device_id *match;
+	struct aspeed_ltpi_priv *priv;
+	int irq, ret;
+
+	match = of_match_device(dev->driver->of_match_table, dev);
+	if (match && match->data) {
+		if (of_property_match_string(np, "compatible", match->compatible) == 0)
+			return 0;
+		else
+			return -ENODEV;
+	}
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->dev = dev;
+	priv->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->regs))
+		return PTR_ERR(priv->regs);
+
+	priv->ltpi_clk = devm_clk_get(&pdev->dev, "ltpi");
+	if (IS_ERR(priv->ltpi_clk)) {
+		priv->ltpi_clk = devm_clk_get(&pdev->dev, "ahb");
+		if (IS_ERR(priv->ltpi_clk))
+			return PTR_ERR(priv->ltpi_clk);
+
+		clk_prepare_enable(priv->ltpi_clk);
+
+		priv->ltpi_phyclk = devm_clk_get(&pdev->dev, "phy");
+		if (IS_ERR(priv->ltpi_phyclk))
+			return PTR_ERR(priv->ltpi_phyclk);
+
+		clk_prepare_enable(priv->ltpi_phyclk);
+	} else {
+		priv->ltpi_phyclk = NULL;
+	}
+
+	priv->ltpi_rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
+	if (IS_ERR(priv->ltpi_rst))
+		return PTR_ERR(priv->ltpi_rst);
+
+	reset_control_deassert(priv->ltpi_rst);
+
+	priv->i2c_tunneling = GENMASK(MAX_I2C_IN_LTPI - 1, 0);
+	if (!of_property_read_u32(np, "i2c-tunneling", &ret))
+		priv->i2c_tunneling = ret;
+
+	priv->scu = syscon_regmap_lookup_by_phandle(np, "aspeed,scu");
+	if (of_get_property(np, "remote-controller", NULL)) {
+		u32 reg;
+
+		/* Clear all the pins/otp strap but LTPI related settings for AST1700 */
+		regmap_read(priv->scu, SCU_IO_PINS_TRAP1, &reg);
+		reg &= ~SCU_IO_PINS_TRAP_LTPI;
+		regmap_write(priv->scu, SCU_IO_PINS_TRAP1_CLEAR, reg);
+
+		regmap_read(priv->scu, SCU_IO_OTP_TRAP1, &reg);
+		regmap_write(priv->scu, SCU_IO_OTP_TRAP1_CLEAR, reg);
+
+		regmap_read(priv->scu, SCU_IO_OTP_TRAP2, &reg);
+		regmap_write(priv->scu, SCU_IO_OTP_TRAP2_CLEAR, reg);
+	} else {
+		irq = platform_get_irq(pdev, 0);
+		ret = devm_request_irq(priv->dev, irq, aspeed_ltpi_irq_handler,
+				       0, dev_name(priv->dev), priv);
+		if (ret) {
+			dev_err(priv->dev, "failed to request irq\n");
+			reset_control_assert(priv->ltpi_rst);
+			clk_disable_unprepare(priv->ltpi_phyclk);
+			clk_disable_unprepare(priv->ltpi_clk);
+			return ret;
+		}
+
+		writel(LTPI_INTR_EN_OP_LINK_LOST, priv->regs + LTPI_INTR_STATUS);
+		writel(LTPI_INTR_EN_OP_LINK_LOST, priv->regs + LTPI_INTR_EN);
+	}
+
+	aspeed_ltpi_init_mux(priv);
+
+	platform_set_drvdata(pdev, priv);
+	if (np)
+		of_platform_populate(np, NULL, lookup, priv->dev);
+
+	return 0;
+}
+
+static int aspeed_ltpi_remove(struct platform_device *pdev)
+{
+	struct aspeed_ltpi_priv *priv;
+
+	priv = platform_get_drvdata(pdev);
+	reset_control_assert(priv->ltpi_rst);
+	clk_disable_unprepare(priv->ltpi_phyclk);
+	clk_disable_unprepare(priv->ltpi_clk);
+
+	return 0;
+}
+
+static const struct of_device_id aspeed_ltpi_of_match[] = {
+	{ .compatible = "aspeed-ltpi", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, aspeed_ltpi_of_match);
+
+static struct platform_driver aspeed_ltpi_driver = {
+	.probe = aspeed_ltpi_probe,
+	.remove = aspeed_ltpi_remove,
+	.driver = {
+		.name = "aspeed-ltpi",
+		.of_match_table = aspeed_ltpi_of_match,
+	},
+};
+
+module_platform_driver(aspeed_ltpi_driver);
+
+MODULE_DESCRIPTION("LVDS Tunneling Protocol and Interface Bus Driver");
+MODULE_AUTHOR("Dylan Hung <dylan_hung@aspeedtech.com>");
+MODULE_LICENSE("GPL");
-- 
2.34.1