[PATCH v3 6/9] i2c: cgbc: Add support for fixed frequency buses

[Thomas Richard (congatec GmbH)]

Some I2C buses run at a fixed frequency. Add a fixed_freq flag to struct
cgbc_i2c_platform_data to identify them. But the frequency is still needed
to compute read_maxtime_us, so split cgbc_i2c_set_frequency() into two
functions:
- cgbc_i2c_set_frequency(): sets the bus frequency (skipped for
  fixed-frequency busses).
- cgbc_i2c_get_frequency(): reads the bus frequency and computes
  read_maxtime_us.

Signed-off-by: Thomas Richard (congatec GmbH) <thomas.richard@xxxxxxxxxxx>
---
 drivers/i2c/busses/i2c-cgbc.c          | 30 +++++++++++++++++++-----------
 include/linux/platform_data/i2c-cgbc.h |  2 ++
 2 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/drivers/i2c/busses/i2c-cgbc.c b/drivers/i2c/busses/i2c-cgbc.c
index d388e07aad84..cb0435b3cc5f 100644
--- a/drivers/i2c/busses/i2c-cgbc.c
+++ b/drivers/i2c/busses/i2c-cgbc.c
@@ -129,7 +129,6 @@ static int cgbc_i2c_set_frequency(struct i2c_adapter *adap,
 	struct cgbc_i2c_data *i2c = i2c_get_adapdata(adap);
 	struct cgbc_device_data *cgbc = i2c->cgbc;
 	u8 cmd[2], data;
-	int ret;
 
 	if (bus_frequency > CGBC_I2C_FREQ_MAX_HZ ||
 	    bus_frequency < CGBC_I2C_FREQ_MIN_HZ) {
@@ -140,18 +139,21 @@ static int cgbc_i2c_set_frequency(struct i2c_adapter *adap,
 	cmd[0] = CGBC_I2C_CMD_SPEED | i2c->bus_id;
 	cmd[1] = cgbc_i2c_freq_to_reg(bus_frequency);
 
-	ret = cgbc_command(cgbc, &cmd, sizeof(cmd), &data, 1, NULL);
-	if (ret)
-		return dev_err_probe(i2c->dev, ret,
-				     "Failed to initialize I2C bus %s",
-				     adap->name);
+	return cgbc_command(cgbc, &cmd, sizeof(cmd), &data, 1, NULL);
+}
 
-	cmd[1] = 0x00;
+static int cgbc_i2c_get_frequency(struct i2c_adapter *adap)
+{
+	struct cgbc_i2c_data *i2c = i2c_get_adapdata(adap);
+	struct cgbc_device_data *cgbc = i2c->cgbc;
+	u8 cmd[2] = { CGBC_I2C_CMD_SPEED | i2c->bus_id };
+	unsigned int bus_frequency;
+	u8 data;
+	int ret;
 
 	ret = cgbc_command(cgbc, &cmd, sizeof(cmd), &data, 1, NULL);
 	if (ret)
-		return dev_err_probe(i2c->dev, ret,
-				     "Failed to get I2C bus frequency");
+		return ret;
 
 	bus_frequency = cgbc_i2c_reg_to_freq(data);
 
@@ -359,9 +361,15 @@ static int cgbc_i2c_probe(struct platform_device *pdev)
 	i2c_set_adapdata(&i2c->adap, i2c);
 	platform_set_drvdata(pdev, i2c);
 
-	ret = cgbc_i2c_set_frequency(&i2c->adap, I2C_MAX_STANDARD_MODE_FREQ);
+	if (!pdata->fixed_freq) {
+		ret = cgbc_i2c_set_frequency(&i2c->adap, I2C_MAX_STANDARD_MODE_FREQ);
+		if (ret)
+			return dev_err_probe(dev, ret, "Failed to set I2C bus frequency");
+	}
+
+	ret = cgbc_i2c_get_frequency(&i2c->adap);
 	if (ret)
-		return ret;
+		return dev_err_probe(i2c->dev, ret, "Failed to get I2C bus frequency");
 
 	return i2c_add_numbered_adapter(&i2c->adap);
 }
diff --git a/include/linux/platform_data/i2c-cgbc.h b/include/linux/platform_data/i2c-cgbc.h
index 4465e8a7b40e..224926c12070 100644
--- a/include/linux/platform_data/i2c-cgbc.h
+++ b/include/linux/platform_data/i2c-cgbc.h
@@ -13,10 +13,12 @@
  * struct cgbc_platform_data - Platform data of the CGBC I2C driver
  * @name:		I2C adapter name
  * @cgbc_bus_id:	I2C bus ID (from Board Controller point of view)
+ * @fixed_freq:		I2C bus has a fixed frequency
  */
 struct cgbc_i2c_platform_data {
 	const char *name;
 	int cgbc_bus_id;
+	bool fixed_freq;
 };
 
 #endif /* _LINUX_I2C_CGBC_H */

-- 
2.53.0