From f2dac8034e28bc0d21da2fb33c8a3c266f4d03fd Mon Sep 17 00:00:00 2001
From: tao89959 <1036524114@qq.com>
Date: Tue, 27 Jan 2026 10:25:08 +0800
Subject: [PATCH] loongson: i2c: support multi bus clock generate mode
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Changelog: 支持多种总线时钟生成模式
Signed-off-by: maoxiaochuan <maoxiaochuan@loongson.cn>
---
 drivers/i2c/busses/i2c-ls2x.c | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-ls2x.c b/drivers/i2c/busses/i2c-ls2x.c
index 94ed16677..47faffdc8 100644
--- a/drivers/i2c/busses/i2c-ls2x.c
+++ b/drivers/i2c/busses/i2c-ls2x.c
@@ -64,7 +64,12 @@
 /* The default bus frequency, which is an empirical value */
 #define LS2X_I2C_FREQ_STD	(33 * HZ_PER_KHZ)
 
+#define I2C_BUS_FREQ_DIV_MODE_D4 (0)
+#define I2C_BUS_FREQ_DIV_MODE_D5 (1)
+#define I2C_BUS_FREQ_DIV_MODE_INVAILD (I2C_BUS_FREQ_DIV_MODE_D5 + 1)
+
 struct ls2x_i2c_priv {
+	u8                  i2c_bus_freq_div_mode;
 	struct i2c_adapter	adapter;
 	void __iomem		*base;
 	struct i2c_timings	i2c_t;
@@ -110,7 +115,11 @@ static void ls2x_i2c_adjust_bus_speed(struct ls2x_i2c_priv *priv)
 	 * otherwise the high bits will be truncated.
 	 * So set the I2C frequency with a sequential writeb() instead of writew().
 	 */
-	val = priv->clock_frequency / (5 * t->bus_freq_hz) - 1;
+	if (priv->i2c_bus_freq_div_mode == I2C_BUS_FREQ_DIV_MODE_D4)
+		val = priv->clock_frequency / (4 * t->bus_freq_hz) - 1;
+	else if ((priv->i2c_bus_freq_div_mode == I2C_BUS_FREQ_DIV_MODE_D5))
+		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);
 }
@@ -331,6 +340,24 @@ static void bus_frequency_get(struct platform_device *pdev, struct device *dev,
 		priv->bus_frequency = 100000; // default 100KHz
 }
 
+static void bus_frequency_div_mode_get(struct platform_device *pdev, struct device *dev, struct ls2x_i2c_priv *priv)
+{
+	u32 mode;
+
+	priv->i2c_bus_freq_div_mode = 255;
+
+	if (!(device_property_read_u32(dev, "bus_div_mode", &mode)))
+		priv->i2c_bus_freq_div_mode = mode;
+	else
+		priv->i2c_bus_freq_div_mode = I2C_BUS_FREQ_DIV_MODE_D5;
+
+	if (mode >= I2C_BUS_FREQ_DIV_MODE_INVAILD)
+		priv->i2c_bus_freq_div_mode = I2C_BUS_FREQ_DIV_MODE_D4;
+
+	if (priv->i2c_bus_freq_div_mode == 255)
+		priv->i2c_bus_freq_div_mode = I2C_BUS_FREQ_DIV_MODE_D4;
+}
+
 static int ls2x_i2c_probe(struct platform_device *pdev)
 {
 	int ret, irq;
@@ -355,6 +382,8 @@ static int ls2x_i2c_probe(struct platform_device *pdev)
 	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);
+	bus_frequency_div_mode_get(pdev, dev, priv);
+	dev_info(dev, "i2c dev bus clock generate mode is %d\n", priv->i2c_bus_freq_div_mode);
 
 	/* Add the i2c adapter */
 	adap = &priv->adapter;