rpmsg: qcom_glink_rpm: Convert to platform remove callback returning void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is (mostly) ignored
and this typically results in resource leaks. To improve here there is a
quest to make the remove callback return void. In the first step of this
quest all drivers are converted to .remove_new() which already returns
void.

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230321154039.355098-3-u.kleine-koenig@pengutronix.de

rpmsg: glink: Fix spelling of peek

The code is peeking into the buffers, not peaking. Fix this throughout
the glink drivers.

Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Reviewed-by: Chris Lew <quic_clew@quicinc.com>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230214224746.1996130-1-quic_bjorande@quicinc.com

rpmsg: glink: Move irq and mbox handling to transports

Not all GLINK transports uses an interrupt and a mailbox instance. The
interrupt for RPM needs to be IRQF_NOSUSPEND, while it seems reasonable
for the SMEM interrupt to use irq_set_wake. The glink struct device is
constructed in the SMEM and RPM drivers but torn down in the core
driver.

Move the interrupt and kick handling into the SMEM and RPM driver, to
improve this and facilitate further improvements.

Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Reviewed-by: Chris Lew <quic_clew@quicinc.com>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230213155215.1237059-5-quic_bjorande@quicinc.com

rpmsg: glink: rpm: Wrap driver context

As with the SMEM driver update, wrap the RPM context in a struct to
facilitate the upcoming changes of moving IRQ and mailbox registration
to the driver.

Reviewed-by: Chris Lew <quic_clew@quicinc.com>
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230213155215.1237059-4-quic_bjorande@quicinc.com

rpmsg: glink: Switch to SPDX license identifier

Use the appropriate SPDX license identifier in various rpmsg
glink driver source files and drop the previous boilerplate
license text.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: glink: Make RX FIFO peak accessor to take an offset

To fully read the received rx data from FIFO both the command and data
has to be read. Currently we read command, data separately and process
them. By adding an offset parameter to RX FIFO peak accessor, command
and data can be read together, simplifying things. So introduce this.

Acked-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: glink: Add support for TX intents

Intents are nothing but pre-allocated buffers of appropriate size that
are allocated on the local side and communicated to the remote side and
the remote stores the list of intent ids that it is informed.

Later when remote side is intenting to send data, it picks up a right
intent (based on the size) and sends the data buffer and the intent id.
Local side receives the data and copies it to the local intent buffer.

The whole idea is to avoid stalls on the transport for allocating
memory, used for copy based transports.

When the remote request to allocate buffers using CMD_RX_INTENT_REQ, we
allocate buffers of requested size, store the buffer id locally and also
communicate the intent id to the remote.

Acked-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: glink: Add support for transport version negotiation

G-link supports a version number and feature flags for each transport.
A combination of the version number and feature flags enable/disable:

(*) G-Link software updates for each edge
(*) Individual features for each edge

Endpoints negotiate both the version and the supported flags when
the transport is opened and they cannot be changed after negotiation has
been completed.

Each full implementation of G-Link must support a minimum of the current
version, the previous version, and the base negotiation version called v0.

Acked-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: glink: Allow unaligned data access

Glink protocol requires that each message is aligned on a 8 byte offset.
This is purely a restriction from glink, so in order to support clients
which do not adher to this, allow data packets of any size, but align
the head index accordingly, effectively removing the alignment
restriction.

Acked-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: glink: Move the common glink protocol implementation to glink_native.c

Move the common part of glink core protocol implementation to
glink_native.c that can be shared with the smem based glink
transport in the later patches.

Acked-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: glink: Split rpm_probe to reuse the common code

There is quite some code common in glink_rpm_probe that can reused for
glink-smem based transport as well. So split the function and move the
code to glink_native_probe that can be used later when we add the
support for glink-smem based transport. Also reuse driver's remove as
well.

Acked-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: glink: Associate indirections for pipe fifo accessor's

With the intention of reusing the glink core protocol commands and code
across both rpm and smem based transports, the only thing different is
way of accessing the shared-memory of the transport (FIFO). So put the
fifo accessor's of the transport's pipe (rx/tx) behind indirections, so
that the rest of the code can be shared.

For this, have a qcom_glink_pipe that can be used in the common code
containing the indirections and wrap it with glink_rpm_pipe that
contains the transport specific members.

Acked-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: glink: Rename glink_rpm_xx functions to qcom_glink_xx

Renaming the glink_rpm_xx functions and structs to qcom_glink_xx
equivalents helps to reuse the core glink protocol while adding
support for smem based glink transport in the later patches.

Acked-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

rpmsg: Introduce Qualcomm RPM glink driver

This introduces a basic driver for communicating over "native glink"
with the RPM found in Qualcomm platforms.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>