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SubjectRe: [PATCH v2 4/9] platform/chrome: Add support for raw commands in sysfs
Hi Enric, thanks for the comments. I'll send out a new version soon,
with this moved to debugfs.

On Tue, Jan 15, 2019 at 12:37 PM Enric Balletbo Serra
<eballetbo@gmail.com> wrote:
>
> Hi Nick,
>
> Missatge de Nick Crews <ncrews@google.com> del dia dl., 14 de gen.
> 2019 a les 23:07:
> >
> > From: Duncan Laurie <dlaurie@google.com>
> >
> > Add a sysfs 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.
> >
>
> Shouldn't you use debugfs for all this stuff instead?

Yes, I probably should. I've moved this all to there in the newest version.

>
>
> > > echo 00 f0 38 00 03 00 > /sys/bus/platform/devices/GOOG000C\:00/raw
> > > cat /sys/bus/platform/devices/GOOG000C\:00/raw
> > 00 37 33 38 65 64 00...
> >
> > Signed-off-by: Duncan Laurie <dlaurie@google.com>
> > Signed-off-by: Nick Crews <ncrews@google.com>
> > ---
> >
> > Changes in v2:
> > - Add sysfs documentation
> > - rm duplicate EC_MAILBOX_DATA_SIZE defs
> > - Make docstrings follow kernel style
> > - Fix tags in commit msg
> > - Reading raw now includes ASCII translation
> >
> > .../ABI/testing/sysfs-platform-wilcoec | 21 ++++
> > drivers/platform/chrome/wilco_ec/Kconfig | 9 ++
> > drivers/platform/chrome/wilco_ec/legacy.c | 99 +++++++++++++++++++
> > drivers/platform/chrome/wilco_ec/legacy.h | 46 +++++++++
> > drivers/platform/chrome/wilco_ec/sysfs.c | 6 ++
> > 5 files changed, 181 insertions(+)
> >
> > diff --git a/Documentation/ABI/testing/sysfs-platform-wilcoec b/Documentation/ABI/testing/sysfs-platform-wilcoec
> > index 09552338c160..cac2cf11835f 100644
> > --- a/Documentation/ABI/testing/sysfs-platform-wilcoec
> > +++ b/Documentation/ABI/testing/sysfs-platform-wilcoec
> > @@ -24,3 +24,24 @@ Description:
> > off and remain off even if activated from the off state.
> > External monitors connected to the system are not affected.
> > In addition Wireless devices are turned off.
> > +
> > +What: /sys/bus/platform/devices/GOOG000C\:00/raw
> > +Date: January 2019
> > +KernelVersion: 4.19
> > +Description:
> > + Write and read raw mailbox commands to the EC.
> > +
> > + For writing:
> > + Bytes 0-1 indicate the message type:
> > + 00 F0 = Execute Legacy Command
> > + 00 F2 = Read/Write NVRAM Property
> > + Byte 2 provides the command code
> > + Bytes 3+ consist of the data passed in the request
> > +
> > + Example:
> > + // Request EC info type 3 (EC firmware build date)
> > + $ echo 00 f0 38 00 03 00 > raw
> > + // View the result. The decoded ASCII result "12/21/18" is
> > + // included after the raw hex.
> > + $ cat raw
> > + 00 31 32 2f 32 31 2f 31 38 00 38 00 01 00 2f 00 .12/21/18.8...
> > diff --git a/drivers/platform/chrome/wilco_ec/Kconfig b/drivers/platform/chrome/wilco_ec/Kconfig
> > index f8e6c9e8c5cd..0bd84c98b79b 100644
> > --- a/drivers/platform/chrome/wilco_ec/Kconfig
> > +++ b/drivers/platform/chrome/wilco_ec/Kconfig
> > @@ -21,4 +21,13 @@ config WILCO_EC
> > To compile this driver as a module, choose M here: the
> > module will be called wilco_ec.
> >
> > +config WILCO_EC_SYSFS_RAW
> > + bool "Enable raw access to EC via sysfs"
> > + depends on WILCO_EC
> > + help
> > + If you say Y here, you get support for sending raw commands to
> > + the Wilco EC via sysfs. These commands do not do any byte
> > + manipulation and allow for testing arbitrary commands. This
> > + interface is intended for debug only and is disabled by default.
> > +
> > endif # WILCO_EC_PLATFORM
> > diff --git a/drivers/platform/chrome/wilco_ec/legacy.c b/drivers/platform/chrome/wilco_ec/legacy.c
> > index 1fdf94d22f57..79bac5dccb39 100644
> > --- a/drivers/platform/chrome/wilco_ec/legacy.c
> > +++ b/drivers/platform/chrome/wilco_ec/legacy.c
> > @@ -11,6 +11,105 @@
> >
> > #include "legacy.h"
> >
> > +#ifdef CONFIG_WILCO_EC_SYSFS_RAW
> > +
> > +/* Raw data buffer, large enough to hold extended responses */
> > +static size_t raw_response_size;
> > +static u8 raw_response_data[EC_MAILBOX_DATA_SIZE_EXTENDED];
> > +
> > +ssize_t wilco_ec_raw_store(struct device *dev, struct device_attribute *attr,
> > + const char *buf, size_t count)
> > +{
> > + struct wilco_ec_device *ec = dev_get_drvdata(dev);
> > + struct wilco_ec_message msg;
> > + u8 raw_request_data[EC_MAILBOX_DATA_SIZE];
> > + int in_offset = 0;
> > + int out_offset = 0;
> > + int ret;
> > +
> > + while (in_offset < count) {
> > + char word_buf[EC_MAILBOX_DATA_SIZE];
> > + u8 byte;
> > + int start_offset = in_offset;
> > + int end_offset;
> > +
> > + /* Find the start of the byte */
> > + while (buf[start_offset] && isspace(buf[start_offset]))
> > + start_offset++;
> > + if (!buf[start_offset])
> > + break;
> > +
> > + /* Find the start of the next byte, if any */
> > + end_offset = start_offset;
> > + while (buf[end_offset] && !isspace(buf[end_offset]))
> > + end_offset++;
> > + if (start_offset > count || end_offset > count)
> > + break;
> > + if (start_offset > EC_MAILBOX_DATA_SIZE ||
> > + end_offset > EC_MAILBOX_DATA_SIZE)
> > + break;
> > +
> > + /* Copy to a new NULL terminated string */
> > + memcpy(word_buf, buf + start_offset, end_offset - start_offset);
> > + word_buf[end_offset - start_offset] = '\0';
> > +
> > + /* Convert from hex string */
> > + ret = kstrtou8(word_buf, 16, &byte);
> > + if (ret)
> > + break;
> > +
> > + /* Fill this byte into the request buffer */
> > + raw_request_data[out_offset++] = byte;
> > + if (out_offset >= EC_MAILBOX_DATA_SIZE)
> > + break;
> > +
> > + in_offset = end_offset;
> > + }
> > + if (out_offset == 0)
> > + return -EINVAL;
> > +
> > + /* Clear response data buffer */
> > + memset(raw_response_data, '\0', EC_MAILBOX_DATA_SIZE_EXTENDED);
> > +
> > + msg.type = raw_request_data[0] << 8 | raw_request_data[1];
> > + msg.flags = WILCO_EC_FLAG_RAW;
> > + msg.command = raw_request_data[2];
> > + msg.request_data = raw_request_data + 3;
> > + msg.request_size = out_offset - 3;
> > + msg.response_data = raw_response_data;
> > + msg.response_size = EC_MAILBOX_DATA_SIZE;
> > +
> > + /* Telemetry commands use extended response data */
> > + if (msg.type == WILCO_EC_MSG_TELEMETRY) {
> > + msg.flags |= WILCO_EC_FLAG_EXTENDED_DATA;
> > + msg.response_size = EC_MAILBOX_DATA_SIZE_EXTENDED;
> > + }
> > +
> > + ret = wilco_ec_mailbox(ec, &msg);
> > + if (ret < 0)
> > + return ret;
> > + raw_response_size = ret;
> > + return count;
> > +}
> > +
> > +ssize_t wilco_ec_raw_show(struct device *dev, struct device_attribute *attr,
> > + char *buf)
> > +{
> > + ssize_t count = 0;
> > +
> > + if (raw_response_size) {
> > + count = hex_dump_to_buffer(raw_response_data, raw_response_size,
> > + 16, 1, buf, PAGE_SIZE, true);
> > +
> > + /* Only return response the first time it is read */
> > + raw_response_size = 0;
> > + }
> > +
> > + return count;
> > +}
> > +
> > +#endif /* CONFIG_WILCO_EC_SYSFS_RAW */
> > +
> > struct ec_info {
> > u8 index;
> > const char *label;
> > diff --git a/drivers/platform/chrome/wilco_ec/legacy.h b/drivers/platform/chrome/wilco_ec/legacy.h
> > index 5c857cb57fa9..340787d25d44 100644
> > --- a/drivers/platform/chrome/wilco_ec/legacy.h
> > +++ b/drivers/platform/chrome/wilco_ec/legacy.h
> > @@ -14,6 +14,52 @@
> > #define EC_INFO_SIZE 9
> > #define EC_COMMAND_STEALTH_MODE 0xfc
> >
> > +#ifdef CONFIG_WILCO_EC_SYSFS_RAW
> > +
> > +/**
> > + * wilco_ec_raw_store() - Write a raw command to EC, store result to view later
> > + * @dev: Device representing the EC
> > + * @attr: The attribute in question
> > + * @buf: Input buffer, format explained below
> > + * @count: Number of bytes in input buffer
> > + *
> > + * Bytes 0-1 indicate the message type:
> > + * 00 F0 = Execute Legacy Command
> > + * 00 F2 = Read/Write NVRAM Property
> > + * Byte 2 provides the command code
> > + * Bytes 3+ consist of the data passed in the request
> > + *
> > + * example: read the EC info type 3 (EC firmware build date):
> > + * # echo 00 f0 38 00 03 00 > raw
> > + *
> > + * After calling this function, read the result by using raw_show()
> > + *
> > + * Return: Number of bytes consumed from input, negative error code on failure
> > + */
> > +ssize_t wilco_ec_raw_store(struct device *dev, struct device_attribute *attr,
> > + const char *buf, size_t count);
> > +
> > +/**
> > + * wilco_ec_raw_show() - Show result from previous call to raw_store()
> > + * @dev: Device representing the EC
> > + * @attr: The attribute in question
> > + * @buf: Output buffer to be filled
> > + *
> > + * Example usage:
> > + * // Call raw_store(), read EC info type 3 (EC firmware build date)
> > + * # echo 00 f0 38 00 03 00 > raw
> > + * // Call this function, view the result. The decoded ASCII result
> > + * // "12/21/18" is included after the raw hex.
> > + * # cat raw
> > + * 00 31 32 2f 32 31 2f 31 38 00 38 00 01 00 2f 00 .12/21/18.8.../.
> > + *
> > + * Return: Number of bytes written to output, negative error code on failure
> > + */
> > +ssize_t wilco_ec_raw_show(struct device *dev, struct device_attribute *attr,
> > + char *buf);
> > +
> > +#endif /* CONFIG_WILCO_EC_SYSFS_RAW */
> > +
> > /**
> > * wilco_ec_version_show() - Display Wilco Embedded Controller version info
> > *
> > diff --git a/drivers/platform/chrome/wilco_ec/sysfs.c b/drivers/platform/chrome/wilco_ec/sysfs.c
> > index e78a3ec3506b..0611a73fcdce 100644
> > --- a/drivers/platform/chrome/wilco_ec/sysfs.c
> > +++ b/drivers/platform/chrome/wilco_ec/sysfs.c
> > @@ -28,9 +28,15 @@ __ATTR(_name, 0644, wilco_ec_##_name##_show, wilco_ec_##_name##_store)
> > /* Make top-level attributes, which will live inside GOOG000C:00/ */
> > static struct device_attribute version_attr = WILCO_EC_ATTR_RO(version);
> > static struct device_attribute stealth_attr = WILCO_EC_ATTR_WO(stealth_mode);
> > +#ifdef CONFIG_WILCO_EC_SYSFS_RAW
> > +static struct device_attribute raw_attr = WILCO_EC_ATTR_RW(raw);
> > +#endif
> > static struct attribute *wilco_ec_toplevel_attrs[] = {
> > &version_attr.attr,
> > &stealth_attr.attr,
> > +#ifdef CONFIG_WILCO_EC_SYSFS_RAW
> > + &raw_attr.attr,
> > +#endif
> > NULL
> > };
> > ATTRIBUTE_GROUPS(wilco_ec_toplevel);
> > --
> > 2.20.1.97.g81188d93c3-goog
> >

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