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In order to optimize the data transfer, let's use the async DMA operation
for writing (queuing) data to the host.
In the async path, the completion event for the transfer ring will only be
sent to the host when the controller driver notifies the MHI stack of the
actual transfer completion using the callback (mhi_ep_skb_completion)
supplied in "struct mhi_ep_buf_info".
Also to accommodate the async operation, the transfer ring read offset
(ring->rd_offset) is cached in the "struct mhi_ep_chan" and updated locally
to let the stack queue further ring items to the controller driver. But the
actual read offset of the transfer ring will only be updated in the
completion callback.
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
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MHI spec defines the interrupt moderation timer feature using which the
host can limit the number of interrupts being raised for an event ring by
the device. This feature allows the host to process multiple event ring
elements by a single IRQ from the device, thereby eliminating the need to
process IRQ for each element.
The INTMODT field in the event context array provides the value to be used
for delaying the IRQ generation from device. This value, along with the
Block Event Interrupt (BEI) flag of the TRE defines how IRQ is generated to
the host.
Support for interrupt moderation timer is implemented using delayed
workqueue in kernel. And a separate delayed work item is used for each
event ring.
Link: https://lore.kernel.org/r/20231026045513.12981-1-manivannan.sadhasivam@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
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Add support for suspending and resuming the channels in MHI endpoint stack.
The channels will be moved to the suspended state during M3 state
transition and will be resumed during M0 transition.
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20220405135754.6622-18-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Add support for handling SYS_ERR (System Error) condition in the MHI
endpoint stack. The SYS_ERR flag will be asserted by the endpoint device
when it detects an internal error. The host will then issue reset and
reinitializes MHI to recover from the error state.
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20220405135754.6622-13-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Add support for managing the MHI state machine by controlling the state
transitions. Only the following MHI state transitions are supported:
1. Ready state
2. M0 state
3. M3 state
4. SYS_ERR state
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20220405135754.6622-8-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Add support for sending the events to the host over MHI bus from the
endpoint. Following events are supported:
1. Transfer completion event
2. Command completion event
3. State change event
4. Execution Environment (EE) change event
An event is sent whenever an operation has been completed in the MHI EP
device. Event is sent using the MHI event ring and additionally the host
is notified using an IRQ if required.
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20220405135754.6622-7-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Add support for managing the MHI ring. The MHI ring is a circular queue
of data structures used to pass the information between host and the
endpoint.
MHI support 3 types of rings:
1. Transfer ring
2. Event ring
3. Command ring
All rings reside inside the host memory and the MHI EP device maps it to
the device memory using blocks like PCIe iATU. The mapping is handled in
the MHI EP controller driver itself.
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20220405135754.6622-6-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Add support for managing the Memory Mapped Input Output (MMIO) registers
of the MHI bus. All MHI operations are carried out using the MMIO registers
by both host and the endpoint device.
The MMIO registers reside inside the endpoint device memory (fixed
location based on the platform) and the address is passed by the MHI EP
controller driver during its registration.
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20220405135754.6622-5-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This commit adds support for registering MHI endpoint controller drivers
with the MHI endpoint stack. MHI endpoint controller drivers manage
the interaction with the host machines (such as x86). They are also the
MHI endpoint bus master in charge of managing the physical link between
the host and endpoint device. Eventhough the MHI spec is bus agnostic,
the current implementation is entirely based on PCIe bus.
The endpoint controller driver encloses all information about the
underlying physical bus like PCIe. The registration process involves
parsing the channel configuration and allocating an MHI EP device.
Channels used in the endpoint stack follows the perspective of the MHI
host stack. i.e.,
UL - From host to endpoint
DL - From endpoint to host
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20220405135754.6622-2-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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