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authorLinus Torvalds <torvalds@linux-foundation.org>2014-02-15 16:17:51 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-02-15 16:17:51 -0800
commit2d0ef4fb34b0462d84a2d87292144b9dad79c8d0 (patch)
tree76e98a2ba1cae8baf1ce8e96f64b16aa98a41f2d
parent5a667a0c02f3d24eb82a44074d24524c17e1ad34 (diff)
parentfde1e418ab2c4269035f7f576e678b6ad3117d7d (diff)
downloadlinux-stericsson-2d0ef4fb34b0462d84a2d87292144b9dad79c8d0.tar.gz
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
-rw-r--r--Documentation/i2c/instantiating-devices41
-rw-r--r--drivers/i2c/busses/i2c-mv64xxx.c33
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);