From ddc84e010fc28fa553249395fb77773ff2a4e341 Mon Sep 17 00:00:00 2001
From: tao89959 <1036524114@qq.com>
Date: Tue, 27 Jan 2026 10:02:03 +0800
Subject: [PATCH] loongson: i2c: support clock and bus freq from dts or acpi
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Changelog: 龙芯i2c驱动支持输入时钟和总线时钟从dts或acpi获取
Signed-off-by: maoxiaochuan <maoxiaochuan@loongson.cn>
---
 drivers/i2c/busses/i2c-ls2x.c | 66 +++++++++++++++++++++++++++++++----
 1 file changed, 59 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-ls2x.c b/drivers/i2c/busses/i2c-ls2x.c
index b475dd27b..94ed16677 100644
--- a/drivers/i2c/busses/i2c-ls2x.c
+++ b/drivers/i2c/busses/i2c-ls2x.c
@@ -25,6 +25,7 @@
 #include <linux/platform_device.h>
 #include <linux/property.h>
 #include <linux/units.h>
+#include <linux/clk.h>
 
 /* I2C Registers */
 #define I2C_LS2X_PRER_LO	0x0 /* Freq Division Low Byte Register */
@@ -68,6 +69,8 @@ struct ls2x_i2c_priv {
 	void __iomem		*base;
 	struct i2c_timings	i2c_t;
 	struct completion	cmd_complete;
+	u32                 bus_frequency;
+	u64                 clock_frequency;
 };
 
 /*
@@ -98,21 +101,16 @@ static void ls2x_i2c_adjust_bus_speed(struct ls2x_i2c_priv *priv)
 	u16 val;
 	struct i2c_timings *t = &priv->i2c_t;
 	struct device *dev = priv->adapter.dev.parent;
-	u32 acpi_speed = i2c_acpi_find_bus_speed(dev);
 
 	i2c_parse_fw_timings(dev, t, false);
 
-	if (acpi_speed || t->bus_freq_hz)
-		t->bus_freq_hz = max(t->bus_freq_hz, acpi_speed);
-	else
-		t->bus_freq_hz = LS2X_I2C_FREQ_STD;
-
+	t->bus_freq_hz = priv->bus_frequency;
 	/*
 	 * According to the chip manual, we can only access the registers as bytes,
 	 * otherwise the high bits will be truncated.
 	 * So set the I2C frequency with a sequential writeb() instead of writew().
 	 */
-	val = LS2X_I2C_PCLK_FREQ / (5 * t->bus_freq_hz) - 1;
+	val = priv->clock_frequency / (5 * t->bus_freq_hz) - 1;
 	writeb(FIELD_GET(GENMASK(7, 0), val), priv->base + I2C_LS2X_PRER_LO);
 	writeb(FIELD_GET(GENMASK(15, 8), val), priv->base + I2C_LS2X_PRER_HI);
 }
@@ -284,6 +282,55 @@ static const struct i2c_algorithm ls2x_i2c_algo = {
 	.functionality = ls2x_i2c_func,
 };
 
+static void clock_frequency_get(struct platform_device *pdev, struct device *dev, struct ls2x_i2c_priv *priv)
+{
+	int err;
+	u32 clk;
+	struct clk *clk_unit;
+
+	if (!(device_property_read_u32(dev, "clock-frequency", &clk)))
+		priv->clock_frequency = clk;
+	else {
+		clk_unit = devm_clk_get(&pdev->dev, "i2c-clk");
+
+		if(IS_ERR(clk_unit))
+			goto err_def;
+
+		err = clk_prepare_enable(clk_unit);
+		if (err)
+			goto err_def;
+
+		clk = clk_get_rate(clk_unit);
+		if (!clk) {
+			clk_disable_unprepare(clk_unit);
+			goto err_def;
+		}
+
+		priv->clock_frequency = clk;
+		clk_unit = NULL;
+		return;
+err_def:
+		pr_info("i2c-ls2x %s warning: cant get i2c input clock, default value 125000000", pdev->name);
+		priv->clock_frequency = 125000000;
+		clk_unit = NULL;
+	}
+}
+
+static void bus_frequency_get(struct platform_device *pdev, struct device *dev, struct ls2x_i2c_priv *priv)
+{
+	u32 bus_freq;
+
+	priv->bus_frequency = 0;
+
+	if (!(device_property_read_u32(dev, "bus_freq", &bus_freq)))
+		priv->bus_frequency = bus_freq;
+	else
+		priv->bus_frequency = i2c_acpi_find_bus_speed(dev);
+
+	if (!(priv->bus_frequency))
+		priv->bus_frequency = 100000; // default 100KHz
+}
+
 static int ls2x_i2c_probe(struct platform_device *pdev)
 {
 	int ret, irq;
@@ -304,6 +351,11 @@ static int ls2x_i2c_probe(struct platform_device *pdev)
 	if (irq < 0)
 		return irq;
 
+	clock_frequency_get(pdev, dev, priv);
+	dev_info(dev, "i2c dev input clock is %lld Hz\n", priv->clock_frequency);
+	bus_frequency_get(pdev, dev, priv);
+	dev_info(dev, "i2c dev bus clock is %d Hz\n", priv->bus_frequency);
+
 	/* Add the i2c adapter */
 	adap = &priv->adapter;
 	adap->retries = 5;