[PATCH v11 5/7] i2c: davinci: add support for setting bus frequency

[Marcus Folkesson <marcus.folkesson@gmail.com>]

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

Remove bus_freq_hz entirely and only use clock_hz instead.

Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
---
 drivers/i2c/busses/i2c-davinci.c | 33 +++++++++++++++++++++++++--------
 1 file changed, 25 insertions(+), 8 deletions(-)

diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
index f543997c31e9..06e8af83df0e 100644
--- a/drivers/i2c/busses/i2c-davinci.c
+++ b/drivers/i2c/busses/i2c-davinci.c
@@ -132,8 +132,6 @@ struct davinci_i2c_dev {
 #ifdef CONFIG_CPU_FREQ
 	struct notifier_block	freq_transition;
 #endif
-	/* standard bus frequency */
-	unsigned int		bus_freq_Hz;
 	/* Chip has a ICPFUNC register */
 	bool			has_pfunc;
 };
@@ -171,6 +169,7 @@ static void i2c_davinci_calc_clk_dividers(struct davinci_i2c_dev *dev)
 	u32 clkh;
 	u32 clkl;
 	u32 input_clock = clk_get_rate(dev->clk);
+	u32 bus_freq_Hz = dev->adapter.clock_hz;
 
 	/* NOTE: I2C Clock divider programming info
 	 * As per I2C specs the following formulas provide prescaler
@@ -207,16 +206,16 @@ static void i2c_davinci_calc_clk_dividers(struct davinci_i2c_dev *dev)
 	if (device_is_compatible(dev->dev, "ti,keystone-i2c"))
 		d = 6;
 
-	clk = (input_clock / (psc + 1)) / (dev->bus_freq_Hz);
+	clk = (input_clock / (psc + 1)) / (bus_freq_Hz);
 	/* Avoid driving the bus too fast because of rounding errors above */
-	if (input_clock / (psc + 1) / clk > dev->bus_freq_Hz)
+	if (input_clock / (psc + 1) / clk > bus_freq_Hz)
 		clk++;
 	/*
 	 * According to I2C-BUS Spec 2.1, in FAST-MODE LOW period should be at
 	 * least 1.3uS, which is not the case with 50% duty cycle. Driving HIGH
 	 * to LOW ratio as 1 to 2 is more safe.
 	 */
-	if (dev->bus_freq_Hz > I2C_MAX_STANDARD_MODE_FREQ)
+	if (bus_freq_Hz > I2C_MAX_STANDARD_MODE_FREQ)
 		clkl = (clk << 1) / 3;
 	else
 		clkl = (clk >> 1);
@@ -267,7 +266,7 @@ static int i2c_davinci_init(struct davinci_i2c_dev *dev)
 		davinci_i2c_read_reg(dev, DAVINCI_I2C_CLKL_REG));
 	dev_dbg(dev->dev, "CLKH = %d\n",
 		davinci_i2c_read_reg(dev, DAVINCI_I2C_CLKH_REG));
-	dev_dbg(dev->dev, "bus_freq_Hz = %dHz\n", dev->bus_freq_Hz);
+	dev_dbg(dev->dev, "bus_freq_Hz = %dHz\n", dev->adapter.clock_hz);
 
 
 	/* Take the I2C module out of reset: */
@@ -279,6 +278,23 @@ 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);
+
+	/* put I2C into reset */
+	davinci_i2c_reset_ctrl(dev, 0);
+
+	/* compute clock dividers */
+	adap->clock_hz = clock_hz;
+	i2c_davinci_calc_clk_dividers(dev);
+
+	/* Take the I2C module out of reset: */
+	davinci_i2c_reset_ctrl(dev, 1);
+
+	return clock_hz;
+}
+
 /*
  * This routine does i2c bus recovery by using i2c_generic_scl_recovery
  * which is provided by I2C Bus recovery infrastructure.
@@ -755,12 +771,13 @@ static int davinci_i2c_probe(struct platform_device *pdev)
 	dev->dev = &pdev->dev;
 	dev->irq = irq;
 	platform_set_drvdata(pdev, dev);
+	adap = &dev->adapter;
 
 	r = device_property_read_u32(&pdev->dev, "clock-frequency", &prop);
 	if (r)
 		prop = I2C_MAX_STANDARD_MODE_FREQ;
 
-	dev->bus_freq_Hz = prop;
+	adap->clock_hz = prop;
 
 	dev->has_pfunc = device_property_present(&pdev->dev, "ti,has-pfunc");
 
@@ -800,7 +817,6 @@ static int davinci_i2c_probe(struct platform_device *pdev)
 		goto err_unuse_clocks;
 	}
 
-	adap = &dev->adapter;
 	i2c_set_adapdata(adap, dev);
 	adap->owner = THIS_MODULE;
 	adap->class = I2C_CLASS_DEPRECATED;
@@ -809,6 +825,7 @@ 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->set_clk_freq = davinci_i2c_set_clk;
 
 	if (dev->has_pfunc)
 		adap->bus_recovery_info = &davinci_i2c_scl_recovery_info;

-- 
2.54.0