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Date:   Tue, 15 Jan 2019 20:37:24 +0100
From:   Enric Balletbo Serra <eballetbo@...il.com>
To:     Nick Crews <ncrews@...gle.com>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        Guenter Roeck <groeck@...omium.org>,
        Simon Glass <sjg@...omium.org>, dlaurie@...omium.org,
        Duncan Laurie <dlaurie@...gle.com>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Benson Leung <bleung@...omium.org>
Subject: Re: [PATCH v2 4/9] platform/chrome: Add support for raw commands in sysfs

Hi Nick,

Missatge de Nick Crews <ncrews@...gle.com> del dia dl., 14 de gen.
2019 a les 23:07:
>
> From: Duncan Laurie <dlaurie@...gle.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?


> > 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@...gle.com>
> Signed-off-by: Nick Crews <ncrews@...gle.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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