diff options
| -rw-r--r-- | Documentation/i2c/instantiating-devices | 41 | ||||
| -rw-r--r-- | drivers/i2c/busses/i2c-mv64xxx.c | 33 |
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); |