The Wilco Embedded Controller is able to send telemetry data
which is useful for enterprise applications. A daemon running on
the OS sends a command to the EC via a write() to a char device,
and can read the response with a read(). The write() request is
verified by the driver to ensure that it is performing only one
of the whitelisted commands, and that no extraneous data is
being transmitted to the EC. The response is passed directly
back to the reader with no modification.
The character device will appear as /dev/wilco_telemN, where N
is some small non-negative integer, starting with 0. Only one
process may have the file descriptor open at a time. The calling
userspace program needs to keep the device file descriptor open
between the calls to write() and read() in order to preserve the
response. Up to 32 bytes will be available for reading.
For testing purposes, try requesting the EC's firmware build
date, by sending the WILCO_EC_TELEM_GET_VERSION command with
argument index=3. i.e. write [0x38, 0x00, 0x03]
to the device node. An ASCII string of the build date is
returned.
Signed-off-by: Nick Crews <ncrews@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
The 0xF6 command, intended to send and receive 256 byte payloads to
and from the EC, is not needed. The 0xF5 command for 32 byte
payloads is sufficient. This patch removes support for the 0xF6
command and 256 byte payloads.
Signed-off-by: Nick Crews <ncrews@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Boot on AC is a policy which makes the device boot from S5 when AC
power is connected. This is useful for users who want to run their
device headless or with a dock.
Signed-off-by: Nick Crews <ncrews@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
A Property is typically a data item that is stored to NVRAM
by the EC. Each of these data items has an index associated
with it, known as the Property ID (PID). Properties may have
variable lengths, up to a max of WILCO_EC_PROPERTY_MAX_SIZE
bytes. Properties can be simple integers, or they may be more
complex binary data.
This patch adds support for getting and setting properties.
This will be useful for setting the charge algorithm and charge
schedules, which all use properties.
Signed-off-by: Nick Crews <ncrews@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
The current API for the wilco EC mailbox interface is bad.
It assumes that most messages sent to the EC follow a similar structure,
with a command byte in MBOX[0], followed by a junk byte, followed by
actual data. This doesn't happen in several cases, such as setting the
RTC time, using the raw debugfs interface, and reading or writing
properties such as the Peak Shift policy (this last to be submitted soon).
Similarly for the response message from the EC, the current interface
assumes that the first byte of data is always 0, and the second byte
is unused. However, in both setting and getting the RTC time, in the
debugfs interface, and for reading and writing properties, this isn't
true.
The current way to resolve this is to use WILCO_EC_FLAG_RAW* flags to
specify when and when not to skip these initial bytes in the sent and
received message. They are confusing and used so much that they are
normal, and not exceptions. In addition, the first byte of
response in the debugfs interface is still always skipped, which is
weird, since this raw interface should be giving the entire result.
Additionally, sent messages assume the first byte is a command, and so
struct wilco_ec_message contains the "command" field. In setting or
getting properties however, the first byte is not a command, and so this
field has to be filled with a byte that isn't actually a command. This
is again inconsistent.
wilco_ec_message contains a result field as well, copied from
wilco_ec_response->result. The message result field should be removed:
if the message fails, the cause is already logged, and the callers are
alerted. They will never care about the actual state of the result flag.
These flags and different cases make the wilco_ec_transfer() function,
used in wilco_ec_mailbox(), really gross, dealing with a bunch of
different cases. It's difficult to figure out what it is doing.
Finally, making these assumptions about the structure of a message make
it so that the messages do not correspond well with the specification
for the EC's mailbox interface. For instance, this interface
specification may say that MBOX[9] in the received message contains
some information, but the calling code needs to remember that the first
byte of response is always skipped, and because it didn't set the
RESPONSE_RAW flag, the next byte is also skipped, so this information
is actually contained within wilco_ec_message->response_data[7]. This
makes it difficult to maintain this code in the future.
To fix these problems this patch standardizes the mailbox interface by:
- Removing the WILCO_EC_FLAG_RAW* flags
- Removing the command and reserved_raw bytes from wilco_ec_request
- Removing the mbox0 byte from wilco_ec_response
- Simplifying wilco_ec_transfer() because of these changes
- Gives the callers of wilco_ec_mailbox() the responsibility of exactly
and consistently defining the structure of the mailbox request and
response
- Removing command and result from wilco_ec_message.
This results in the reduction of total code, and makes it much more
maintainable and understandable.
Signed-off-by: Nick Crews <ncrews@chromium.org>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
This Embedded Controller has an internal RTC that is exposed
as a standard RTC class driver with read/write functionality.
The driver is added to the drivers/rtc/ so that the maintainer of that
directory will be able to comment on this change, as that maintainer is
the expert on this system. In addition, the driver code is called
indirectly after a corresponding device is registered from core.c,
as opposed to core.c registering the driver callbacks directly.
To test:
> hwclock --show --rtc /dev/rtc1
2007-12-31 16:01:20.460959-08:00
> hwclock --systohc --rtc /dev/rtc1
> hwclock --show --rtc /dev/rtc1
2018-11-29 17:08:00.780793-08:00
> hwclock --show --rtc /dev/rtc1
2007-12-31 16:01:20.460959-08:00
> hwclock --systohc --rtc /dev/rtc1
> hwclock --show --rtc /dev/rtc1
2018-11-29 17:08:00.780793-08:00
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Signed-off-by: Nick Crews <ncrews@chromium.org>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
[Fix the sparse warning: symbol 'wilco_ec_rtc_read/write' was not declared]
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Add a debugfs attribute that allows sending raw commands to the EC.
This is useful for development and debug but should not be enabled
in a production environment.
To test:
Get the EC firmware build date
First send the request command
> echo 00 f0 38 00 03 00 > raw
Then read the result. "12/21/18" is in the middle of the response
> cat raw
00 31 32 2f 32 31 2f 31 38 00 00 0f 01 00 01 00 .12/21/18.......
Get the EC firmware build date
First send the request command
> echo 00 f0 38 00 03 00 > raw
Then read the result. "12/21/18" is in the middle of the response
> cat raw
00 31 32 2f 32 31 2f 31 38 00 00 0f 01 00 01 00 .12/21/18.......
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Signed-off-by: Nick Crews <ncrews@chromium.org>
[Fix off-by-one error in wilco_ec/debugfs.c]
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
This EC is an incompatible variant of the typical Chrome OS embedded
controller. It uses the same low-level communication and a similar
protocol with some significant differences. The EC firmware does
not support the same mailbox commands so it is not registered as a
cros_ec device type. This commit exports the wilco_ec_mailbox()
function so that other modules can use it to communicate with the EC.
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Signed-off-by: Nick Crews <ncrews@chromium.org>
[Fix the sparse warning: symbol 'wilco_ec_transfer' was not declared]
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
[Fix Kconfig dependencies for wilco_ec]
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Nick Crews