Commit 2d0ef4fb authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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
parents 5a667a0c fde1e418
......@@ -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
--------------------------------------------
......
......@@ -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);
......
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