mailbox: Explicitly include correct DT includes

The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it as merged into the regular platform bus.
As part of that merge prepping Arm DT support 13 years ago, they
"temporarily" include each other. They also include platform_device.h
and of.h. As a result, there's a pretty much random mix of those include
files used throughout the tree. In order to detangle these headers and
replace the implicit includes with struct declarations, users need to
explicitly include the correct includes.

Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: Allow direct registration to a channel

Support virtual mailbox controllers and clients which are not platform
devices or come from the devicetree by allowing them to match client to
channel via some other mechanism.

Tested-by: Sudeep Holla <sudeep.holla@arm.com> (pcc)
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: forward the hrtimer if not queued and under a lock

This reverts commit c7dacf5b0f32957b24ef29df1207dc2cd8307743,
"mailbox: avoid timer start from callback"

The previous commit was reverted since it lead to a race that
caused the hrtimer to not be started at all. The check for
hrtimer_active() in msg_submit() will return true if the
callback function txdone_hrtimer() is currently running. This
function could return HRTIMER_NORESTART and then the timer
will not be restarted, and also msg_submit() will not start
the timer. This will lead to a message actually being submitted
but no timer will start to check for its compleation.

The original fix that added checking hrtimer_active() was added to
avoid a warning with hrtimer_forward. Looking in the kernel
another solution to avoid this warning is to check hrtimer_is_queued()
before calling hrtimer_forward_now() instead. This however requires a
lock so the timer is not started by msg_submit() inbetween this check
and the hrtimer_forward() call.

Fixes: c7dacf5b0f32 ("mailbox: avoid timer start from callback")
Signed-off-by: Björn Ardö <bjorn.ardo@axis.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: avoid timer start from callback

If the txdone is done by polling, it is possible for msg_submit() to start
the timer while txdone_hrtimer() callback is running. If the timer needs
recheduling, it could already be enqueued by the time hrtimer_forward_now()
is called, leading hrtimer to loudly complain.

WARNING: CPU: 3 PID: 74 at kernel/time/hrtimer.c:932 hrtimer_forward+0xc4/0x110
CPU: 3 PID: 74 Comm: kworker/u8:1 Not tainted 5.9.0-rc2-00236-gd3520067d01c-dirty #5
Hardware name: Libre Computer AML-S805X-AC (DT)
Workqueue: events_freezable_power_ thermal_zone_device_check
pstate: 20000085 (nzCv daIf -PAN -UAO BTYPE=--)
pc : hrtimer_forward+0xc4/0x110
lr : txdone_hrtimer+0xf8/0x118
[...]

This can be fixed by not starting the timer from the callback path. Which
requires the timer reloading as long as any message is queued on the
channel, and not just when current tx is not done yet.

Fixes: 0cc67945ea59 ("mailbox: switch to hrtimer for tx_complete polling")
Reported-by: Da Xue <da@libre.computer>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Jerome Brunet <jbrunet@baylibre.com>
Tested-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: handle failed named mailbox channel request

Previously, if mbox_request_channel_byname was used with a name
which did not exist in the "mbox-names" property of a mailbox
client, the mailbox corresponding to the last entry in the
"mbox-names" list would be incorrectly selected.
With this patch, -EINVAL is returned if the named mailbox is
not found.

Signed-off-by: Morten Borup Petersen <morten_bp@live.dk>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

Based on 2 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

mailbox: Export mbox_flush()

The mbox_flush() function can be used by drivers that are built as
modules, so the function needs to be exported.

Reported-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: Allow multiple controllers per device

Look through the whole controller list when mapping device tree
phandles to controllers instead of stopping at the first one.

Each controller is intended to only contain one kind of mailbox,
but some devices (like Tegra HSP) implement multiple kinds and use
the same device tree node for all of them. As such, we need to allow
multiple mbox_controllers per device tree node.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: Support blocking transfers in atomic context

The mailbox framework supports blocking transfers via completions for
clients that can sleep. In order to support blocking transfers in cases
where the transmission is not permitted to sleep, add a new ->flush()
callback that controller drivers can implement to busy loop until the
transmission has been completed. A new mbox_flush() function can be
called by mailbox consumers in atomic context to make sure a transfer
has completed.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: Add device-managed registration functions

Add device-managed equivalents of the mbox_controller_register() and
mbox_controller_unregister() functions that can be used to have the
devres infrastructure automatically unregister mailbox controllers on
driver probe failure or driver removal. This can help remove a lot of
boiler plate code from drivers.

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: reset txdone_method TXDONE_BY_POLL if client knows_txdone

Currently the mailbox framework sets txdone_method to TXDONE_BY_POLL if
the controller sets txdone_by_poll. However some clients can have a
mechanism to do TXDONE_BY_ACK which they can specify by knows_txdone.
However, we endup setting both TXDONE_BY_POLL and TXDONE_BY_ACK in that
case. In such scenario, we may end up with below warnings as the tx
ticker is run both by mailbox framework and the client.

WARNING: CPU: 1 PID: 0 at kernel/time/hrtimer.c:805 hrtimer_forward+0x88/0xd8
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.12.0-rc5 #242
Hardware name: ARM LTD ARM Juno Development Platform
task: ffff8009768ca700 task.stack: ffff8009768f8000
PC is at hrtimer_forward+0x88/0xd8
LR is at txdone_hrtimer+0xd4/0xf8
Call trace:
hrtimer_forward+0x88/0xd8
__hrtimer_run_queues+0xe4/0x158
hrtimer_interrupt+0xa4/0x220
arch_timer_handler_phys+0x30/0x40
handle_percpu_devid_irq+0x78/0x130
generic_handle_irq+0x24/0x38
__handle_domain_irq+0x5c/0xb8
gic_handle_irq+0x54/0xa8

This patch fixes the issue by resetting TXDONE_BY_POLL if client has set
knows_txdone.

Cc: Alexey Klimov <alexey.klimov@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: Make startup and shutdown ops optional

Some mailbox hardware doesn't have to perform any additional operations
on startup of shutdown, so make these optional.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: handle empty message in tx_tick

We already check if the message is empty before calling the client
tx_done callback. Calling completion on a wait event is also invalid
if the message is empty.

This patch moves the existing empty message check earlier.

Fixes: 2b6d83e2b8b7 ("mailbox: Introduce framework for mailbox")
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: skip complete wait event if timer expired

If a wait_for_completion_timeout() call returns due to a timeout,
complete() can get called after returning from the wait which is
incorrect and can cause subsequent transmissions on a channel to fail.
Since the wait_for_completion_timeout() sees the completion variable
is non-zero caused by the erroneous/spurious complete() call, and
it immediately returns without waiting for the time as expected by the
client.

This patch fixes the issue by skipping complete() call for the timer
expiry.

Fixes: 2b6d83e2b8b7 ("mailbox: Introduce framework for mailbox")
Reported-by: Alexey Klimov <alexey.klimov@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: always wait in mbox_send_message for blocking Tx mode

There exists a race when msg_submit return immediately as there was an
active request being processed which may have completed just before it's
checked again in mbox_send_message. This will result in return to the
caller without waiting in mbox_send_message even when it's blocking Tx.

This patch fixes the issue by waiting for the completion always if Tx
is in blocking mode.

Fixes: 2b6d83e2b8b7 ("mailbox: Introduce framework for mailbox")
Reported-by: Alexey Klimov <alexey.klimov@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Alexey Klimov <alexey.klimov@arm.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: check ->last_tx_done for NULL in case of timer-based polling

It is allowed by code to register mailbox controller that sets txdone_poll
flag to request timer-based polling with missed ->last_tx_done() method.
If such thing happens and since presence of last_tx_done() is not checked
it will fail in hrtimer callback function txdone_hrtimer() when first
message will be transmitted.

This patch adds check for this method and logging of error on
registration of mailbox controller if it requested timer-based polling.

Signed-off-by: Alexey Klimov <alexey.klimov@arm.com>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

ktime: Cleanup ktime_set() usage

ktime_set(S,N) was required for the timespec storage type and is still
useful for situations where a Seconds and Nanoseconds part of a time value
needs to be converted. For anything where the Seconds argument is 0, this
is pointless and can be replaced with a simple assignment.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>

mailbox: Stop using ENOSYS for anything other than unimplemented syscalls

In accordance with e15f431fe2d5 ("errno.h: Improve ENOSYS's comment") and
91c9afaf97ee ("checkpatch.pl: new instances of ENOSYS are errors") we're
converting from the old meaning of: ENOSYS "Function not implemented" to
a more standard EINVAL.

Reported-by: Seraphin Bonnaffe <seraphin.bonnaffe@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: switch to hrtimer for tx_complete polling

The mailbox core uses jiffy based timer to handle polling for the
transmit completion. If the client/protocol have/support notification
of the last packet transmit completion via ACK packet, then we tick the
Tx state machine immediately in the callback. However if the client
doesn't support that mechanism we might end-up waiting for atleast a
jiffy even though the remote is ready to receive the next request.

This patch switches the timer used for that polling from jiffy-based
to hrtimer-based so that we can support polling at much higher time
resolution.

Reported-and-suggested-by: Juri Lelli <Juri.Lelli@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: Add ability for clients to request channels by name

This patch supplies a new framework API; mbox_request_channel_byname().

It works by supplying the usual client pointer as the first argument and
a string as the second. The API will search the client's node for a
'mbox-names' property then request a channel in the normal way using the
requested string's index as the expected second 'index' argument.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: Fix up error handling in mbox_request_channel()

mbox_request_channel() currently returns EBUSY in the event the controller
is not present or if of_xlate() fails, but in neither case is EBUSY really
appropriate. Return EPROBE_DEFER if the controller is not yet present
and change of_xlate() to return an ERR_PTR instead of NULL so that the
error can be propagated back to the caller of mbox_request_channel().

Signed-off-by: Benson Leung <bleung@chromium.org>
Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Acked-by: Suman Anna <s-anna@ti.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: check for bit set before polling

Before polling we just need to see if the TXDONE_BY_POLL bit
is set in txdone_method. There may be another bit (method)
specified as well, like TXDONE_BY_ACK.

Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>

Mailbox: Add support for Platform Communication Channel

ACPI 5.0+ spec defines a generic mode of communication
between the OS and a platform such as the BMC. This medium
(PCC) is typically used by CPPC (ACPI CPU Performance management),
RAS (ACPI reliability protocol) and MPST (ACPI Memory power
states).

This patch adds PCC support as a Mailbox Controller. As of
ACPI v5.1 there is no provision for clients to lookup mailbox
controllers in a way that Linux expects. e.g. in DT the clients
can list the mailboxes they can associate with in the DT binding
and then provide a unique index to lookup a channel within a mailbox.
Since the ACPI spec doesn't have anything similar, we introduce a
mailbox controller specific API so that when the client calls it,
we know to lookup in the context of a specific controller. This
also helps in keeping a consistent interface across DT and ACPI
for such drivers.

This patch implements basic PCC support using the ACPI v5.1
structures. IRQ mode support will be provided as follow up patches.

Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: add tx_prepare client callback

If the mailbox controller expects the payload is in place before
initiating the transmit, then it's impossible to reuse the list
maintained by core mailbox code currently. Maintaining another list
for sending the message in the controller seems totally unnecessary
as core mailbox library already provides that feature.

This patch introduces tx_prepare callback in mbox_client which
can be used by the core mailbox library before initiating the
transaction through mbox->ops->send_data. The client driver can
implement this callback to ensure the payload is copied to the
shared memory.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: Don't unnecessarily re-arm the polling timer

poll_txdone() will unconditionally re-arm the polling timer if there was
an active request, even if the active request completed and no other
requests were submitted. This is fixed by:
- only re-arming the timer if the controller reported that the current
transmission has not completed, and,
- moving the call to poll_txdone() into msg_submit() so that the
controller gets polled (and the timer re-armed, if necessary) whenever
a new message is submitted.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

mailbox: Introduce framework for mailbox

Introduce common framework for client/protocol drivers and
controller drivers of Inter-Processor-Communication (IPC).

Client driver developers should have a look at
include/linux/mailbox_client.h to understand the part of
the API exposed to client drivers.
Similarly controller driver developers should have a look
at include/linux/mailbox_controller.h

Reviewed-by: Mark Brown <broonie@linaro.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>