linux/Documentation/ABI/testing/debugfs-wilco-ec
Nick Crews 9e2b0e0be6 platform/chrome: wilco_ec: Add h1_gpio status to debugfs
As part of Chrome OS's FAFT (Fully Automated Firmware Testing)
tests, we need to ensure that the H1 chip is properly setting
some GPIO lines. The h1_gpio attribute exposes the state
of the lines:
- ENTRY_TO_FACT_MODE in BIT(0)
- SPI_CHROME_SEL in BIT(1)

There are two reasons that I am exposing this in debugfs,
and not as a GPIO:
1. This is only useful for testing, so end users shouldn't ever
care about this. In fact, if it passes the tests, then the value of
h1_gpio will always be 2, so it would be really uninteresting for users.
2. This GPIO is not connected to, controlled by, or really even related
to the AP. The GPIO runs between the EC and the H1 security chip.

Changes in v4:
- Use "0x02x\n" instead of "02x\n" for format string
- Use DEFINE_DEBUGFS_ATTRIBUTE()
- Add documentation
Changes in v3:
- Fix documentation to correspond with formatting change in v2.
Changes in v2:
- Zero out the unused fields in the request.
- Format result as "%02x\n" instead of as a decimal.

Signed-off-by: Nick Crews <ncrews@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
2019-04-16 11:00:36 +02:00

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What: /sys/kernel/debug/wilco_ec/h1_gpio
Date: April 2019
KernelVersion: 5.2
Description:
As part of Chrome OS's FAFT (Fully Automated Firmware Testing)
tests, we need to ensure that the H1 chip is properly setting
some GPIO lines. The h1_gpio attribute exposes the state
of the lines:
- ENTRY_TO_FACT_MODE in BIT(0)
- SPI_CHROME_SEL in BIT(1)
Output will formatted with "0x%02x\n".
What: /sys/kernel/debug/wilco_ec/raw
Date: January 2019
KernelVersion: 5.1
Description:
Write and read raw mailbox commands to the EC.
You can write a hexadecimal sentence to raw, and that series of
bytes will be sent to the EC. Then, you can read the bytes of
response by reading from raw.
For writing, bytes 0-1 indicate the message type, one of enum
wilco_ec_msg_type. Byte 2+ consist of the data passed in the
request, starting at MBOX[0]
At least three bytes are required for writing, two for the type
and at least a single byte of data. Only the first
EC_MAILBOX_DATA_SIZE bytes of MBOX will be used.
Example:
// Request EC info type 3 (EC firmware build date)
// Corresponds with sending type 0x00f0 with
// MBOX = [38, 00, 03, 00]
$ echo 00 f0 38 00 03 00 > /sys/kernel/debug/wilco_ec/raw
// View the result. The decoded ASCII result "12/21/18" is
// included after the raw hex.
// Corresponds with MBOX = [00, 00, 31, 32, 2f, 32, 31, 38, ...]
$ cat /sys/kernel/debug/wilco_ec/raw
00 00 31 32 2f 32 31 2f 31 38 00 38 00 01 00 2f 00 ..12/21/18.8...
Note that the first 32 bytes of the received MBOX[] will be
printed, even if some of the data is junk. It is up to you to
know how many of the first bytes of data are the actual
response.