linux-kernel - [PATCH RFC 6/7] i2c: davinci: add support for setting bus frequency

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Message-Id: <20250922-i2c-mux-v1-6-28c94a610930@gmail.com>
Date: Mon, 22 Sep 2025 08:21:01 +0200
From: Marcus Folkesson <marcus.folkesson@...il.com>
To: Wolfram Sang <wsa+renesas@...g-engineering.com>, 
 Peter Rosin <peda@...ntia.se>, 
 Michael Hennerich <michael.hennerich@...log.com>, 
 Bartosz Golaszewski <brgl@...ev.pl>, Andi Shyti <andi.shyti@...nel.org>
Cc: linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, 
 Marcus Folkesson <marcus.folkesson@...il.com>
Subject: [PATCH RFC 6/7] i2c: davinci: add support for setting bus
 frequency

Populate adapter with clock_hz and set_clk_freq to enable support for
dynamic bus frequency.

Signed-off-by: Marcus Folkesson <marcus.folkesson@...il.com>
---
 drivers/i2c/busses/i2c-davinci.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
index 6b18938457d0c5cabc323c364d9330c2890df107..d3e47738f8ee7e8f69fee49509dcda396c9b7fb6 100644
--- a/drivers/i2c/busses/i2c-davinci.c
+++ b/drivers/i2c/busses/i2c-davinci.c
@@ -279,6 +279,27 @@ static int i2c_davinci_init(struct davinci_i2c_dev *dev)
 	return 0;
 }
 
+static int davinci_i2c_set_clk(struct i2c_adapter *adap, u32 clock_hz)
+{
+	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
+
+	if (dev->bus_freq == clock_hz)
+		return 0;
+
+	dev->bus_freq = clock_hz;
+
+	/* put I2C into reset */
+	davinci_i2c_reset_ctrl(dev, 0);
+
+	/* compute clock dividers */
+	i2c_davinci_calc_clk_dividers(dev);
+
+	/* Take the I2C module out of reset: */
+	davinci_i2c_reset_ctrl(dev, 1);
+
+	return 0;
+}
+
 /*
  * This routine does i2c bus recovery by using i2c_generic_scl_recovery
  * which is provided by I2C Bus recovery infrastructure.
@@ -810,6 +831,8 @@ static int davinci_i2c_probe(struct platform_device *pdev)
 	adap->dev.parent = &pdev->dev;
 	adap->timeout = DAVINCI_I2C_TIMEOUT;
 	adap->dev.of_node = dev_of_node(&pdev->dev);
+	adap->clock_hz = dev->bus_freq;
+	adap->set_clk_freq = davinci_i2c_set_clk;
 
 	if (dev->has_pfunc)
 		adap->bus_recovery_info = &davinci_i2c_scl_recovery_info;

-- 
2.50.1