Re: [PATCH v5] platform/x86: thinkpad_acpi: lap or desk mode interface

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On Fri, Jul 3, 2020 at 4:24 AM Mark Pearson <markpearson@xxxxxxxxxx> wrote:
>
> Newer Lenovo Thinkpad platforms have support to identify whether the
> system is on-lap or not using an ACPI DYTC event from the firmware.
>
> This patch provides the ability to retrieve the current mode via sysfs
> entrypoints and will be used by userspace for thermal mode and WWAN
> functionality

Hans, do you think it's good to have custom ABI for this? I think you
may be know better what types of ABI we already have for such thing.

> Co-developed-by: Nitin Joshi <njoshi1@xxxxxxxxxx>
> Signed-off-by: Nitin Joshi <njoshi1@xxxxxxxxxx>
> Reviewed-by: Sugumaran <slacshiminar@xxxxxxxxxx>
> Reviewed-by: Bastien Nocera <bnocera@xxxxxxxxxx>
> Signed-off-by: Mark Pearson <markpearson@xxxxxxxxxx>
> ---
> Changes in v5:
>  - Updated with review changes from Andy Shevchenko
>  - Added ABI information to thinkpad-acpi.rst
>  - improved error handling and parameter passing as recommended
>  - code cleanup as recommended
>  - added review tag from bnocera
> Changes in v4:
>  - Correct hotkey event comment as we're handling event
>  - Remove unnecessary check in dytc_lapmode_refresh
> Changes in v3:
> - Fixed inaccurate comments
> - Used BIT macro to check lapmode bit setting as recommended and update
>   define name
> - Check for new_state == dytc_lapmode in dytc_lapmode_refresh
> Changes in v2:
> - cleaned up initialisation sequence to be cleaner and avoid spamming
>   platforms that don't have DYTC with warning message. Tested on P52
> - Adding platform-driver-x86 mailing list for review as requested
>
>  .../admin-guide/laptops/thinkpad-acpi.rst     |  15 +++
>  drivers/platform/x86/thinkpad_acpi.c          | 111 +++++++++++++++++-
>  2 files changed, 124 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/admin-guide/laptops/thinkpad-acpi.rst b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> index 822907dcc845..99066aa8d97b 100644
> --- a/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> +++ b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> @@ -50,6 +50,7 @@ detailed description):
>         - WAN enable and disable
>         - UWB enable and disable
>         - LCD Shadow (PrivacyGuard) enable and disable
> +       - Lap mode sensor
>
>  A compatibility table by model and feature is maintained on the web
>  site, http://ibm-acpi.sf.net/. I appreciate any success or failure
> @@ -1432,6 +1433,20 @@ The first command ensures the best viewing angle and the latter one turns
>  on the feature, restricting the viewing angles.
>
>
> +DYTC Lapmode sensor
> +------------------
> +
> +sysfs: dytc_lapmode
> +
> +Newer thinkpads and mobile workstations have the ability to determine if
> +the device is in deskmode or lapmode. This feature is used by user space
> +to decide if WWAN transmission can be increased to maximum power and is
> +also useful for understanding the different thermal modes available as
> +they differ between desk and lap mode.
> +
> +The property is read-only. If the platform doesn't have support the sysfs
> +class is not created.
> +
>  EXPERIMENTAL: UWB
>  -----------------
>
> diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
> index ff7f0a4f2475..037eb77414f9 100644
> --- a/drivers/platform/x86/thinkpad_acpi.c
> +++ b/drivers/platform/x86/thinkpad_acpi.c
> @@ -4022,8 +4022,8 @@ static bool hotkey_notify_6xxx(const u32 hkey,
>                 return true;
>         case TP_HKEY_EV_THM_CSM_COMPLETED:
>                 pr_debug("EC reports: Thermal Control Command set completed (DYTC)\n");
> -               /* recommended action: do nothing, we don't have
> -                * Lenovo ATM information */
> +               /* Thermal event - pass on to event handler */
> +               tpacpi_driver_event(hkey);
>                 return true;
>         case TP_HKEY_EV_THM_TRANSFM_CHANGED:
>                 pr_debug("EC reports: Thermal Transformation changed (GMTS)\n");
> @@ -9795,6 +9795,105 @@ static struct ibm_struct lcdshadow_driver_data = {
>         .write = lcdshadow_write,
>  };
>
> +/*************************************************************************
> + * DYTC subdriver, for the Lenovo lapmode feature
> + */
> +
> +#define DYTC_CMD_GET          2 /* To get current IC function and mode */
> +#define DYTC_GET_LAPMODE_BIT 17 /* Set when in lapmode */
> +
> +static bool dytc_lapmode;
> +
> +static void dytc_lapmode_notify_change(void)
> +{
> +       sysfs_notify(&tpacpi_pdev->dev.kobj, NULL, "dytc_lapmode");
> +}
> +
> +static int dytc_command(int command, int *output)
> +{
> +       acpi_handle dytc_handle;
> +
> +       if (ACPI_FAILURE(acpi_get_handle(hkey_handle, "DYTC", &dytc_handle))) {
> +               /* Platform doesn't support DYTC */
> +               return -ENODEV;
> +       }
> +       if (!acpi_evalf(dytc_handle, output, NULL, "dd", command))
> +               return -EIO;
> +       return 0;
> +}
> +
> +static int dytc_lapmode_get(bool *state)
> +{
> +       int output, err;
> +
> +       err = dytc_command(DYTC_CMD_GET, &output);
> +       if (err)
> +               return err;
> +       *state = output & BIT(DYTC_GET_LAPMODE_BIT) ? true : false;
> +       return 0;
> +}
> +
> +static void dytc_lapmode_refresh(void)
> +{
> +       bool new_state;
> +       int err;
> +
> +       err = dytc_lapmode_get(&new_state);
> +       if (err || (new_state == dytc_lapmode))
> +               return;
> +
> +       dytc_lapmode = new_state;
> +       dytc_lapmode_notify_change();
> +}
> +
> +/* sysfs lapmode entry */
> +static ssize_t dytc_lapmode_show(struct device *dev,
> +                                       struct device_attribute *attr,
> +                                       char *buf)
> +{
> +       return snprintf(buf, PAGE_SIZE, "%d\n", dytc_lapmode);
> +}
> +
> +static DEVICE_ATTR_RO(dytc_lapmode);
> +
> +static struct attribute *dytc_attributes[] = {
> +       &dev_attr_dytc_lapmode.attr,
> +       NULL,
> +};
> +
> +static const struct attribute_group dytc_attr_group = {
> +       .attrs = dytc_attributes,
> +};
> +
> +static int tpacpi_dytc_init(struct ibm_init_struct *iibm)
> +{
> +       int err;
> +
> +       err = dytc_lapmode_get(&dytc_lapmode);
> +       /* If support isn't available (ENODEV) then don't return an error
> +        * but just don't create the sysfs group
> +        */
> +       if (err == -ENODEV)
> +               return 0;
> +       /* For all other errors we can flag the failure */
> +       if (err)
> +               return err;
> +
> +       /* Platform supports this feature - create the group */
> +       err = sysfs_create_group(&tpacpi_pdev->dev.kobj, &dytc_attr_group);
> +       return err;
> +}
> +
> +static void dytc_exit(void)
> +{
> +       sysfs_remove_group(&tpacpi_pdev->dev.kobj, &dytc_attr_group);
> +}
> +
> +static struct ibm_struct dytc_driver_data = {
> +       .name = "dytc",
> +       .exit = dytc_exit,
> +};
> +
>  /****************************************************************************
>   ****************************************************************************
>   *
> @@ -9842,6 +9941,10 @@ static void tpacpi_driver_event(const unsigned int hkey_event)
>
>                 mutex_unlock(&kbdlight_mutex);
>         }
> +
> +       if (hkey_event == TP_HKEY_EV_THM_CSM_COMPLETED)
> +               dytc_lapmode_refresh();
> +
>  }
>
>  static void hotkey_driver_event(const unsigned int scancode)
> @@ -10280,6 +10383,10 @@ static struct ibm_init_struct ibms_init[] __initdata = {
>                 .init = tpacpi_lcdshadow_init,
>                 .data = &lcdshadow_driver_data,
>         },
> +       {
> +               .init = tpacpi_dytc_init,
> +               .data = &dytc_driver_data,
> +       },
>  };
>
>  static int __init set_ibm_param(const char *val, const struct kernel_param *kp)
> --
> 2.26.2
>


-- 
With Best Regards,
Andy Shevchenko


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