[PATH v3 4/4] i2c: i2c-diolan-u2c: sysfs bus frequency support

[Octavian Purdila <octavian.purdila-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

Add support for showing and changing the bus frequency via
sysfs.

Tested on a DLN2 adapter run in U2C-12 compatibility mode.

Cc: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
Signed-off-by: Octavian Purdila <octavian.purdila-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 drivers/i2c/busses/i2c-diolan-u2c.c | 49 +++++++++++++++++++++++++------------
 1 file changed, 34 insertions(+), 15 deletions(-)

diff --git a/drivers/i2c/busses/i2c-diolan-u2c.c b/drivers/i2c/busses/i2c-diolan-u2c.c
index b19a310..ff4e120 100644
--- a/drivers/i2c/busses/i2c-diolan-u2c.c
+++ b/drivers/i2c/busses/i2c-diolan-u2c.c
@@ -71,6 +71,9 @@
 #define U2C_I2C_FREQ_STD	100000
 #define U2C_I2C_FREQ(s)		(1000000 / (2 * (s - 1) + 10))
 
+#define U2C_I2C_MIN_FREQ	U2C_I2C_FREQ(U2C_I2C_SPEED_2KHZ)
+#define U2C_I2C_MAX_FREQ	U2C_I2C_FREQ_FAST
+
 #define DIOLAN_USB_TIMEOUT	100	/* in ms */
 #define DIOLAN_SYNC_TIMEOUT	20	/* in ms */
 
@@ -298,31 +301,24 @@ static void diolan_get_serial(struct i2c_diolan_u2c *dev)
 	}
 }
 
-static int diolan_init(struct i2c_diolan_u2c *dev)
+static int diolan_set_freq(struct i2c_adapter *adapter, unsigned int *frequency)
 {
+	struct i2c_diolan_u2c *dev = i2c_get_adapdata(adapter);
 	int speed, ret;
 
-	if (frequency >= 200000) {
+	if (*frequency >= 200000) {
 		speed = U2C_I2C_SPEED_FAST;
-		frequency = U2C_I2C_FREQ_FAST;
-	} else if (frequency >= 100000 || frequency == 0) {
+		*frequency = U2C_I2C_FREQ_FAST;
+	} else if (*frequency >= 100000 || *frequency == 0) {
 		speed = U2C_I2C_SPEED_STD;
-		frequency = U2C_I2C_FREQ_STD;
+		*frequency = U2C_I2C_FREQ_STD;
 	} else {
-		speed = U2C_I2C_SPEED(frequency);
+		speed = U2C_I2C_SPEED(*frequency);
 		if (speed > U2C_I2C_SPEED_2KHZ)
 			speed = U2C_I2C_SPEED_2KHZ;
-		frequency = U2C_I2C_FREQ(speed);
+		*frequency = U2C_I2C_FREQ(speed);
 	}
 
-	dev_info(&dev->interface->dev,
-		 "Diolan U2C at USB bus %03d address %03d speed %d Hz\n",
-		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum, frequency);
-
-	diolan_flush_input(dev);
-	diolan_fw_version(dev);
-	diolan_get_serial(dev);
-
 	/* Set I2C speed */
 	ret = diolan_set_speed(dev, speed);
 	if (ret < 0)
@@ -336,6 +332,23 @@ static int diolan_init(struct i2c_diolan_u2c *dev)
 	if (speed != U2C_I2C_SPEED_FAST)
 		ret = diolan_set_clock_synch_timeout(dev, DIOLAN_SYNC_TIMEOUT);
 
+	return 0;
+}
+
+static int diolan_init(struct i2c_diolan_u2c *dev)
+{
+	int ret;
+
+	diolan_flush_input(dev);
+	diolan_fw_version(dev);
+	diolan_get_serial(dev);
+
+	ret = diolan_set_freq(&dev->adapter, &frequency);
+
+	dev_info(&dev->interface->dev,
+		 "Diolan U2C at USB bus %03d address %03d speed %d Hz\n",
+		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum, frequency);
+
 	return ret;
 }
 
@@ -471,6 +484,9 @@ static int diolan_u2c_probe(struct usb_interface *interface,
 	dev->adapter.owner = THIS_MODULE;
 	dev->adapter.class = I2C_CLASS_HWMON;
 	dev->adapter.algo = &diolan_usb_algorithm;
+	dev->adapter.min_freq = U2C_I2C_MIN_FREQ;
+	dev->adapter.max_freq = U2C_I2C_MAX_FREQ;
+	dev->adapter.set_freq = diolan_set_freq;
 	i2c_set_adapdata(&dev->adapter, dev);
 	snprintf(dev->adapter.name, sizeof(dev->adapter.name),
 		 DRIVER_NAME " at bus %03d device %03d",
@@ -485,6 +501,9 @@ static int diolan_u2c_probe(struct usb_interface *interface,
 		goto error_free;
 	}
 
+	/* set the current bus frequency */
+	dev->adapter.freq = frequency;
+
 	/* and finally attach to i2c layer */
 	ret = i2c_add_adapter(&dev->adapter);
 	if (ret < 0) {
-- 
1.9.1