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

2 files changed, 53 insertions, 21 deletions

diff --git a/Documentation/i2c/instantiating-devices b/Documentation/i2c/instantiating-devices
index c70e7a7638d1..0d85ac1935b7 100644
--- a/Documentation/i2c/instantiating-devices
+++ b/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
 --------------------------------------------
 
diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index b8c5187b9ee0..d52d84937ad3 100644
--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/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);