On Thu, Aug 22, 2019 at 2:48 PM Alexander Schremmer
<alex@xxxxxxxxxxxxxxx> wrote:
>
> This feature is found optionally in T480s, T490, T490s.
>
> The feature is called lcdshadow and visible via
> /proc/acpi/ibm/lcdshadow.
>
> The ACPI methods \_SB.PCI0.LPCB.EC.HKEY.{GSSS,SSSS,TSSS,CSSS} are
> available in these machines. They get, set, toggle or change the state
> apparently.
>
> The patch was tested on a 5.0 series kernel on a T480s.
>
Pushed to my review and testing queue, thanks!
> Signed-off-by: Alexander Schremmer <alex@xxxxxxxxxxxxxxx>
> ---
> .../admin-guide/laptops/thinkpad-acpi.rst | 23 ++++
> drivers/platform/x86/thinkpad_acpi.c | 112 ++++++++++++++++++
> 2 files changed, 135 insertions(+)
>
> diff --git a/Documentation/admin-guide/laptops/thinkpad-acpi.rst b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> index adea0bf2acc5..822907dcc845 100644
> --- a/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> +++ b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> @@ -49,6 +49,7 @@ detailed description):
> - Fan control and monitoring: fan speed, fan enable/disable
> - WAN enable and disable
> - UWB enable and disable
> + - LCD Shadow (PrivacyGuard) enable and disable
>
> A compatibility table by model and feature is maintained on the web
> site, http://ibm-acpi.sf.net/. I appreciate any success or failure
> @@ -1409,6 +1410,28 @@ Sysfs notes
> Documentation/driver-api/rfkill.rst for details.
>
>
> +LCD Shadow control
> +------------------
> +
> +procfs: /proc/acpi/ibm/lcdshadow
> +
> +Some newer T480s and T490s ThinkPads provide a feature called
> +PrivacyGuard. By turning this feature on, the usable vertical and
> +horizontal viewing angles of the LCD can be limited (as if some privacy
> +screen was applied manually in front of the display).
> +
> +procfs notes
> +^^^^^^^^^^^^
> +
> +The available commands are::
> +
> + echo '0' >/proc/acpi/ibm/lcdshadow
> + echo '1' >/proc/acpi/ibm/lcdshadow
> +
> +The first command ensures the best viewing angle and the latter one turns
> +on the feature, restricting the viewing angles.
> +
> +
> EXPERIMENTAL: UWB
> -----------------
>
> diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
> index 7bde4640ef34..12bf573c6568 100644
> --- a/drivers/platform/x86/thinkpad_acpi.c
> +++ b/drivers/platform/x86/thinkpad_acpi.c
> @@ -9714,6 +9714,114 @@ static struct ibm_struct battery_driver_data = {
> .exit = tpacpi_battery_exit,
> };
>
> +/*************************************************************************
> + * LCD Shadow subdriver, for the Lenovo PrivacyGuard feature
> + */
> +
> +
> +static int lcdshadow_state;
> +
> +static int lcdshadow_on_off(bool state)
> +{
> + acpi_handle set_shadow_handle;
> + int output;
> +
> + if (ACPI_FAILURE(acpi_get_handle(
> + hkey_handle,
> + "SSSS",
> + &set_shadow_handle))) {
> + pr_warn("Thinkpad ACPI has no %s interface.\n", "SSSS");
> + return -EIO;
> + }
> +
> + if (!acpi_evalf(set_shadow_handle, &output, NULL, "dd", (int)state))
> + return -EIO;
> +
> + lcdshadow_state = state;
> + return 0;
> +}
> +
> +static int lcdshadow_set(bool on)
> +{
> + if (lcdshadow_state < 0)
> + return lcdshadow_state;
> + if (lcdshadow_state == on)
> + return 0;
> + return lcdshadow_on_off(on);
> +}
> +
> +static int tpacpi_lcdshadow_init(struct ibm_init_struct *iibm)
> +{
> + acpi_handle get_shadow_handle;
> + int output;
> +
> + if (ACPI_FAILURE(acpi_get_handle(
> + hkey_handle,
> + "GSSS",
> + &get_shadow_handle))) {
> + lcdshadow_state = -ENODEV;
> + return 0;
> + }
> +
> + if (!acpi_evalf(get_shadow_handle, &output, NULL, "dd", 0)) {
> + lcdshadow_state = -EIO;
> + return -EIO;
> + }
> + if (!(output & 0x10000)) {
> + lcdshadow_state = -ENODEV;
> + return 0;
> + }
> + lcdshadow_state = output & 0x1;
> +
> + return 0;
> +}
> +
> +static void lcdshadow_resume(void)
> +{
> + if (lcdshadow_state >= 0)
> + lcdshadow_on_off(lcdshadow_state);
> +}
> +
> +static int lcdshadow_read(struct seq_file *m)
> +{
> + if (lcdshadow_state < 0) {
> + seq_puts(m, "status:\t\tnot supported\n");
> + } else {
> + seq_printf(m, "status:\t\t%d\n", lcdshadow_state);
> + seq_puts(m, "commands:\t0, 1\n");
> + }
> +
> + return 0;
> +}
> +
> +static int lcdshadow_write(char *buf)
> +{
> + char *cmd;
> + int state = -1;
> +
> + if (lcdshadow_state < 0)
> + return -ENODEV;
> +
> + while ((cmd = next_cmd(&buf))) {
> + if (strlencmp(cmd, "0") == 0)
> + state = 0;
> + else if (strlencmp(cmd, "1") == 0)
> + state = 1;
> + }
> +
> + if (state == -1)
> + return -EINVAL;
> +
> + return lcdshadow_set(state);
> +}
> +
> +static struct ibm_struct lcdshadow_driver_data = {
> + .name = "lcdshadow",
> + .resume = lcdshadow_resume,
> + .read = lcdshadow_read,
> + .write = lcdshadow_write,
> +};
> +
> /****************************************************************************
> ****************************************************************************
> *
> @@ -10195,6 +10303,10 @@ static struct ibm_init_struct ibms_init[] __initdata = {
> .init = tpacpi_battery_init,
> .data = &battery_driver_data,
> },
> + {
> + .init = tpacpi_lcdshadow_init,
> + .data = &lcdshadow_driver_data,
> + },
> };
>
> static int __init set_ibm_param(const char *val, const struct kernel_param *kp)
> --
> 2.20.1
>
--
With Best Regards,
Andy Shevchenko
