Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/…

…kernel/git/wsa/linux

Pull i2c fixes from Wolfram Sang:
 "i2c has a bugfix and documentation improvements for you"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  Documentation: i2c: mention ACPI method for instantiating devices
  Documentation: i2c: describe devicetree method for instantiating devices
  i2c: mv64xxx: refactor message start to ensure proper initialization

Documentation/i2c/instantiating-devices

@@ -8,8 +8,8 @@ reason, the kernel code must instantiate I2C devices explicitly. There are
 several ways to achieve this, depending on the context and requirements.
 
 
-Method 1: Declare the I2C devices by bus number
------------------------------------------------
+Method 1a: Declare the I2C devices by bus number
+------------------------------------------------
 
 This method is appropriate when the I2C bus is a system bus as is the case
 for many embedded systems. On such systems, each I2C bus has a number
@@ -51,6 +51,43 @@ The devices will be automatically unbound and destroyed when the I2C bus
 they sit on goes away (if ever.)
 
 
+Method 1b: Declare the I2C devices via devicetree
+-------------------------------------------------
+
+This method has the same implications as method 1a. The declaration of I2C
+devices is here done via devicetree as subnodes of the master controller.
+
+Example:
+
+	i2c1: i2c@400a0000 {
+		/* ... master properties skipped ... */
+		clock-frequency = <100000>;
+
+		flash@50 {
+			compatible = "atmel,24c256";
+			reg = <0x50>;
+		};
+
+		pca9532: gpio@60 {
+			compatible = "nxp,pca9532";
+			gpio-controller;
+			#gpio-cells = <2>;
+			reg = <0x60>;
+		};
+	};
+
+Here, two devices are attached to the bus using a speed of 100kHz. For
+additional properties which might be needed to set up the device, please refer
+to its devicetree documentation in Documentation/devicetree/bindings/.
+
+
+Method 1c: Declare the I2C devices via ACPI
+-------------------------------------------
+
+ACPI can also describe I2C devices. There is special documentation for this
+which is currently located at Documentation/acpi/enumeration.txt.
+
+
 Method 2: Instantiate the devices explicitly
 --------------------------------------------
 

drivers/i2c/busses/i2c-mv64xxx.c

@@ -97,7 +97,6 @@ enum {
 enum {
 	MV64XXX_I2C_ACTION_INVALID,
 	MV64XXX_I2C_ACTION_CONTINUE,
-	MV64XXX_I2C_ACTION_OFFLOAD_SEND_START,
 	MV64XXX_I2C_ACTION_SEND_START,
 	MV64XXX_I2C_ACTION_SEND_RESTART,
 	MV64XXX_I2C_ACTION_OFFLOAD_RESTART,
@@ -204,6 +203,9 @@ static int mv64xxx_i2c_offload_msg(struct mv64xxx_i2c_data *drv_data)
 	unsigned long ctrl_reg;
 	struct i2c_msg *msg = drv_data->msgs;
 
+	if (!drv_data->offload_enabled)
+		return -EOPNOTSUPP;
+
 	drv_data->msg = msg;
 	drv_data->byte_posn = 0;
 	drv_data->bytes_left = msg->len;
@@ -433,8 +435,7 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
 
 		drv_data->msgs++;
 		drv_data->num_msgs--;
-		if (!(drv_data->offload_enabled &&
-				mv64xxx_i2c_offload_msg(drv_data))) {
+		if (mv64xxx_i2c_offload_msg(drv_data) < 0) {
 			drv_data->cntl_bits |= MV64XXX_I2C_REG_CONTROL_START;
 			writel(drv_data->cntl_bits,
 			drv_data->reg_base + drv_data->reg_offsets.control);
@@ -458,15 +459,14 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
 			drv_data->reg_base + drv_data->reg_offsets.control);
 		break;
 
-	case MV64XXX_I2C_ACTION_OFFLOAD_SEND_START:
-		if (!mv64xxx_i2c_offload_msg(drv_data))
-			break;
-		else
-			drv_data->action = MV64XXX_I2C_ACTION_SEND_START;
-		/* FALLTHRU */
 	case MV64XXX_I2C_ACTION_SEND_START:
-		writel(drv_data->cntl_bits | MV64XXX_I2C_REG_CONTROL_START,
-			drv_data->reg_base + drv_data->reg_offsets.control);
+		/* Can we offload this msg ? */
+		if (mv64xxx_i2c_offload_msg(drv_data) < 0) {
+			/* No, switch to standard path */
+			mv64xxx_i2c_prepare_for_io(drv_data, drv_data->msgs);
+			writel(drv_data->cntl_bits | MV64XXX_I2C_REG_CONTROL_START,
+				drv_data->reg_base + drv_data->reg_offsets.control);
+		}
 		break;
 
 	case MV64XXX_I2C_ACTION_SEND_ADDR_1:
@@ -625,15 +625,10 @@ mv64xxx_i2c_execute_msg(struct mv64xxx_i2c_data *drv_data, struct i2c_msg *msg,
 	unsigned long	flags;
 
 	spin_lock_irqsave(&drv_data->lock, flags);
-	if (drv_data->offload_enabled) {
-		drv_data->action = MV64XXX_I2C_ACTION_OFFLOAD_SEND_START;
-		drv_data->state = MV64XXX_I2C_STATE_WAITING_FOR_START_COND;
-	} else {
-		mv64xxx_i2c_prepare_for_io(drv_data, msg);
 
-		drv_data->action = MV64XXX_I2C_ACTION_SEND_START;
-		drv_data->state = MV64XXX_I2C_STATE_WAITING_FOR_START_COND;
-	}
+	drv_data->action = MV64XXX_I2C_ACTION_SEND_START;
+	drv_data->state = MV64XXX_I2C_STATE_WAITING_FOR_START_COND;
+
 	drv_data->send_stop = is_last;
 	drv_data->block = 1;
 	mv64xxx_i2c_do_action(drv_data);