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.
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
