Date:   Tue, 15 Jan 2019 20:32:19 +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 3/9] platform/chrome: Add sysfs attributes

Hi Nick,

Some few comments more ...

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 some sample sysfs attributes for the Wilco EC that show how
> the mailbox interface works. "Legacy" attributes are those that
> existed in the EC before it was adapted to ChromeOS.
>
> > cat /sys/bus/platform/devices/GOOG000C\:00/version
> Label        : 99.99.99
> SVN Revision : 738ed.99
> Model Number : 08;8
> Build Date   : 08/30/18
>
> Signed-off-by: Duncan Laurie <dlaurie@...gle.com>
> Signed-off-by: Nick Crews <ncrews@...gle.com>
> ---
>
> Changes in v2:
> - Remove license boiler plate
> - Remove "wilco_ec_sysfs -" docstring prefix
> - Fix accidental Makefile deletion
> - Add documentation for sysfs entries
> - Change "enable ? 0 : 1" to "!enable"
> - No longer override error code from sysfs_init()
> - Put attributes in the legacy file to begin with, don't move later
> - Remove duplicate error messages in sysfs_init() and its caller
>
>  .../ABI/testing/sysfs-platform-wilcoec        | 26 ++++++
>  drivers/platform/chrome/wilco_ec/Makefile     |  2 +-
>  drivers/platform/chrome/wilco_ec/core.c       | 15 +++
>  drivers/platform/chrome/wilco_ec/legacy.c     | 91 +++++++++++++++++++
>  drivers/platform/chrome/wilco_ec/legacy.h     | 47 ++++++++++
>  drivers/platform/chrome/wilco_ec/sysfs.c      | 66 ++++++++++++++
>  include/linux/platform_data/wilco-ec.h        | 14 +++
>  7 files changed, 260 insertions(+), 1 deletion(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-platform-wilcoec

I'd like to rename this to sysfs-platform-wilco-ec (like cros-ec)

>  create mode 100644 drivers/platform/chrome/wilco_ec/legacy.c
>  create mode 100644 drivers/platform/chrome/wilco_ec/legacy.h
>  create mode 100644 drivers/platform/chrome/wilco_ec/sysfs.c
>
> diff --git a/Documentation/ABI/testing/sysfs-platform-wilcoec b/Documentation/ABI/testing/sysfs-platform-wilcoec
> new file mode 100644
> index 000000000000..09552338c160
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-platform-wilcoec
> @@ -0,0 +1,26 @@
> +What:          /sys/bus/platform/devices/GOOG000C\:00/version
> +Date:          January 2019
> +KernelVersion: 4.19

That will be probably 5.1

> +Description:
> +               Display Wilco Embedded Controller version info
> +
> +               Output will be similar to the example below:
> +               Label        : 95.00.06
> +               SVN Revision : 5960a.06
> +               Model Number : 08;8
> +               Build Date   : 11/29/18
> +
> +               Although this contains multiple pieces of data in a single sysfs
> +               attribute (inconsistent with normal sysfs conventions),
> +               this format was chosen to be consistent with the version
> +               attribute in /sys/class/chomeos/<device>/version
> +

I don't buy the reason to be inconsistent. I don't think you need to
be consistent with something that is wrong and not following the
conventions. Past errors should be fixed :)

I'd like to see here single values in single attributes, this will
also be easier to parse from userspace point of view.

> +What:          /sys/bus/platform/devices/GOOG000C\:00/stealth_mode
> +Date:          January 2019
> +KernelVersion: 4.19
> +Description:
> +               Turn stealth_mode on or off on EC. Stealth mode means that the
> +               various LEDs, the LCD backlight, and onboard speakers are turned
> +               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.

Would be good to specify the valid values to write.

> diff --git a/drivers/platform/chrome/wilco_ec/Makefile b/drivers/platform/chrome/wilco_ec/Makefile
> index 03b32301dc61..7965a39e2e7a 100644
> --- a/drivers/platform/chrome/wilco_ec/Makefile
> +++ b/drivers/platform/chrome/wilco_ec/Makefile
> @@ -1,4 +1,4 @@
>  # SPDX-License-Identifier: GPL-2.0
>
> -wilco_ec-objs                          := core.o mailbox.o
> +wilco_ec-objs                          := core.o mailbox.o sysfs.o legacy.o
>  obj-$(CONFIG_WILCO_EC)                 += wilco_ec.o
> diff --git a/drivers/platform/chrome/wilco_ec/core.c b/drivers/platform/chrome/wilco_ec/core.c
> index 2d1d8d3f9a94..3193e8b2ec91 100644
> --- a/drivers/platform/chrome/wilco_ec/core.c
> +++ b/drivers/platform/chrome/wilco_ec/core.c
> @@ -64,11 +64,26 @@ static int wilco_ec_probe(struct platform_device *pdev)
>         cros_ec_lpc_mec_init(ec->io_packet->start,
>                              ec->io_packet->start + EC_MAILBOX_DATA_SIZE);
>
> +       /* Create sysfs attributes for userspace interaction */
> +       ret = wilco_ec_sysfs_init(ec);
> +       if (ret < 0) {
> +               dev_err(dev, "Failed to create sysfs attributes\n");
> +               goto destroy_lpc_mec;
> +       }
>         return 0;
> +
> +destroy_lpc_mec:
> +       cros_ec_lpc_mec_destroy();
> +       return ret;
>  }
>
>  static int wilco_ec_remove(struct platform_device *pdev)
>  {
> +       struct wilco_ec_device *ec = platform_get_drvdata(pdev);
> +
> +       /* Remove sysfs attributes */
> +       wilco_ec_sysfs_remove(ec);
> +
>         /* Teardown cros_ec interface */
>         cros_ec_lpc_mec_destroy();
>
> diff --git a/drivers/platform/chrome/wilco_ec/legacy.c b/drivers/platform/chrome/wilco_ec/legacy.c
> new file mode 100644
> index 000000000000..1fdf94d22f57
> --- /dev/null
> +++ b/drivers/platform/chrome/wilco_ec/legacy.c
> @@ -0,0 +1,91 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Legacy (non-Chrome-specific) sysfs attributes for Wilco EC
> + *
> + * Copyright 2018 Google LLC
> + */
> +
> +#include <linux/ctype.h>
> +#include <linux/device.h>
> +#include <linux/platform_data/wilco-ec.h>
> +
> +#include "legacy.h"
> +
> +struct ec_info {
> +       u8 index;
> +       const char *label;
> +};
> +
> +static ssize_t wilco_ec_show_info(struct wilco_ec_device *ec, char *buf,
> +                                 ssize_t count, struct ec_info *info)
> +{
> +       char result[EC_INFO_SIZE];
> +       struct wilco_ec_message msg = {
> +               .type = WILCO_EC_MSG_LEGACY,
> +               .command = EC_COMMAND_EC_INFO,
> +               .request_data = &info->index,
> +               .request_size = sizeof(info->index),
> +               .response_data = result,
> +               .response_size = EC_INFO_SIZE,
> +       };
> +       int ret;
> +
> +       ret = wilco_ec_mailbox(ec, &msg);
> +       if (ret != EC_INFO_SIZE)
> +               return scnprintf(buf + count, PAGE_SIZE - count,
> +                                "%-12s : ERROR %d\n", info->label, ret);
> +
> +       return scnprintf(buf + count, PAGE_SIZE - count,
> +                        "%-12s : %s\n", info->label, result);
> +}
> +
> +ssize_t wilco_ec_version_show(struct device *dev, struct device_attribute *attr,
> +                             char *buf)
> +{
> +       struct wilco_ec_device *ec = dev_get_drvdata(dev);
> +       struct ec_info wilco_ec_info[] = {
> +               { 0, "Label" },
> +               { 1, "SVN Revision" },
> +               { 2, "Model Number" },
> +               { 3, "Build Date" },
> +               { 0xff, NULL },
> +       };
> +       struct ec_info *info = wilco_ec_info;
> +       ssize_t c = 0;
> +
> +       for (info = wilco_ec_info; info->label; info++)
> +               c += wilco_ec_show_info(ec, buf, c, info);
> +
> +       return c;
> +}
> +
> +ssize_t wilco_ec_stealth_mode_store(struct device *dev,
> +                                   struct device_attribute *attr,
> +                                   const char *buf, size_t count)
> +{
> +       struct wilco_ec_device *ec = dev_get_drvdata(dev);
> +       u8 param;
> +       struct wilco_ec_message msg = {
> +               .type = WILCO_EC_MSG_LEGACY,
> +               .command = EC_COMMAND_STEALTH_MODE,
> +               .request_data = &param,
> +               .request_size = sizeof(param),
> +       };
> +       int ret;
> +       bool enable;
> +
> +       ret = kstrtobool(buf, &enable);
> +       if (ret) {
> +               dev_err(dev, "Unable to parse '%s' to bool", buf);
> +               return ret;
> +       }
> +
> +       /* Invert input parameter, EC expects 0=on and 1=off */
> +       param = !enable;
> +
> +       ret = wilco_ec_mailbox(ec, &msg);
> +       if (ret < 0)
> +               return ret;
> +
> +       return count;
> +}
> diff --git a/drivers/platform/chrome/wilco_ec/legacy.h b/drivers/platform/chrome/wilco_ec/legacy.h
> new file mode 100644
> index 000000000000..5c857cb57fa9
> --- /dev/null
> +++ b/drivers/platform/chrome/wilco_ec/legacy.h
> @@ -0,0 +1,47 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Legacy (non-Chrome-specific) sysfs attributes for Wilco EC
> + *
> + * Copyright 2018 Google LLC
> + */
> +
> +#ifndef WILCO_EC_LEGACY_H
> +#define WILCO_EC_LEGACY_H
> +
> +#include <linux/device.h>
> +
> +#define EC_COMMAND_EC_INFO             0x38
> +#define EC_INFO_SIZE                   9
> +#define EC_COMMAND_STEALTH_MODE                0xfc
> +
> +/**
> + * wilco_ec_version_show() - Display Wilco Embedded Controller version info
> + *
> + * Output will be similar to the example below:
> + * Label        : 95.00.06
> + * SVN Revision : 5960a.06
> + * Model Number : 08;8
> + * Build Date   : 11/29/18
> + *
> + * Although this contains multiple pieces of data in a single sysfs attribute
> + * (inconsistent with normal sysfs conventions), this format was chosen to be
> + * consistent with the version attribute in ../cros_ec_sysfs.c
> + */
> +ssize_t wilco_ec_version_show(struct device *dev, struct device_attribute *attr,
> +                             char *buf);
> +
> +/**
> + * wilco_ec_stealth_mode_store() - Turn stealth_mode on or off on EC
> + * @dev: Device representing the EC
> + * @attr: The attribute in question
> + * @buf: Input buffer, should be parseable by kstrtobool(). Anything parsed to
> + *      True means enable stealth mode (turn off screen, etc)
> + * @count: Number of bytes in input buffer
> + *
> + * Return: Number of bytes consumed from input, negative error code on failure
> + */
> +ssize_t wilco_ec_stealth_mode_store(struct device *dev,
> +                                   struct device_attribute *attr,
> +                                   const char *buf, size_t count);
> +
> +#endif /* WILCO_EC_LEGACY_H */
> diff --git a/drivers/platform/chrome/wilco_ec/sysfs.c b/drivers/platform/chrome/wilco_ec/sysfs.c
> new file mode 100644
> index 000000000000..e78a3ec3506b
> --- /dev/null
> +++ b/drivers/platform/chrome/wilco_ec/sysfs.c
> @@ -0,0 +1,66 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Sysfs attributes for Wilco Embedded Controller
> + *
> + * Copyright 2018 Google LLC
> + *
> + * The sysfs attributes appear under /sys/bus/platform/devices/GOOG000C\:00/
> + * To actually learn what each attribute does, read the corresponding _show() or
> + * _store() function source.
> + */
> +
> +#include <linux/ctype.h>
> +#include <linux/platform_data/wilco-ec.h>
> +#include <linux/platform_device.h>
> +#include <linux/sysfs.h>
> +
> +#include "legacy.h"
> +
> +#define WILCO_EC_ATTR_RO(_name)                                                \
> +__ATTR(_name, 0444, wilco_ec_##_name##_show, NULL)
> +
> +#define WILCO_EC_ATTR_WO(_name)                                                \
> +__ATTR(_name, 0200, NULL, wilco_ec_##_name##_store)
> +
> +#define WILCO_EC_ATTR_RW(_name)                                                \
> +__ATTR(_name, 0644, wilco_ec_##_name##_show, wilco_ec_##_name##_store)
> +

Why not use the already defined DEVICE_ATTR_* family instead?

> +/* 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);
> +static struct attribute *wilco_ec_toplevel_attrs[] = {
> +       &version_attr.attr,
> +       &stealth_attr.attr,
> +       NULL
> +};
> +ATTRIBUTE_GROUPS(wilco_ec_toplevel);
> +
> +/**
> + * wilco_ec_sysfs_init() - Initialize the sysfs directories and attributes
> + * @dev: The device representing the EC
> + *
> + * Creates the sysfs directory structure and populates it with all attributes.
> + * If there is a problem it will clean up the entire filesystem.
> + *
> + * Return 0 on success, -ENOMEM on failure creating directories or attibutes.
> + */
> +int wilco_ec_sysfs_init(struct wilco_ec_device *ec)
> +{
> +       struct device *dev = ec->dev;
> +       int ret;
> +
> +       /* add the top-level attributes */
> +       ret = sysfs_create_groups(&dev->kobj, wilco_ec_toplevel_groups);
> +       if (ret)
> +               return -ENOMEM;

Do not overwrite the error, return ret;

> +
> +       return 0;
> +}
> +
> +void wilco_ec_sysfs_remove(struct wilco_ec_device *ec)
> +{
> +       struct device *dev = ec->dev;
> +
> +       /* go upwards through the directory structure */
> +       sysfs_remove_groups(&dev->kobj, wilco_ec_toplevel_groups);
> +}
> diff --git a/include/linux/platform_data/wilco-ec.h b/include/linux/platform_data/wilco-ec.h
> index 5477b8802f81..7c6ab6de7239 100644
> --- a/include/linux/platform_data/wilco-ec.h
> +++ b/include/linux/platform_data/wilco-ec.h
> @@ -135,4 +135,18 @@ struct wilco_ec_response {
>   */
>  int wilco_ec_mailbox(struct wilco_ec_device *ec, struct wilco_ec_message *msg);
>
> +/**
> + * wilco_ec_sysfs_init() - Create sysfs attributes.
> + * @ec: EC device.
> + *
> + * Return: 0 for success or negative error code on failure.
> + */
> +int wilco_ec_sysfs_init(struct wilco_ec_device *ec);
> +
> +/**
> + * wilco_ec_sysfs_remove() - Remove sysfs attributes.
> + * @ec: EC device.
> + */
> +void wilco_ec_sysfs_remove(struct wilco_ec_device *ec);
> +
>  #endif /* WILCO_EC_H */
> --
> 2.20.1.97.g81188d93c3-goog
>

Thanks,
  Enric

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