platform/x86/amd/pmf: Add support to update system state

PMF driver based on the output actions from the TA can request to update
the system states like entering s0i3, lock screen etc. by generating
an uevent. Based on the udev rules set in the userspace the event id
matching the uevent shall get updated accordingly using the systemctl.

Sample udev rules under Documentation/admin-guide/pmf.rst.

Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Link: https://lore.kernel.org/r/20231212014705.2017474-9-Shyam-sundar.S-k@amd.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Documentation/admin-guide/index.rst

@@ -119,6 +119,7 @@ configure specific aspects of kernel behavior to your liking.
    parport
    perf-security
    pm/index
+   pmf
    pnp
    rapidio
    ras

Documentation/admin-guide/pmf.rst

@@ -0,0 +1,24 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Set udev rules for PMF Smart PC Builder
+---------------------------------------
+
+AMD PMF(Platform Management Framework) Smart PC Solution builder has to set the system states
+like S0i3, Screen lock, hibernate etc, based on the output actions provided by the PMF
+TA (Trusted Application).
+
+In order for this to work the PMF driver generates a uevent for userspace to react to. Below are
+sample udev rules that can facilitate this experience when a machine has PMF Smart PC solution builder
+enabled.
+
+Please add the following line(s) to
+``/etc/udev/rules.d/99-local.rules``::
+
+        DRIVERS=="amd-pmf", ACTION=="change", ENV{EVENT_ID}=="0", RUN+="/usr/bin/systemctl suspend"
+        DRIVERS=="amd-pmf", ACTION=="change", ENV{EVENT_ID}=="1", RUN+="/usr/bin/systemctl hibernate"
+        DRIVERS=="amd-pmf", ACTION=="change", ENV{EVENT_ID}=="2", RUN+="/bin/loginctl lock-sessions"
+
+EVENT_ID values:
+0= Put the system to S0i3/S2Idle
+1= Put the system to hibernate
+2= Lock the screen

drivers/platform/x86/amd/pmf/pmf.h

@@ -73,6 +73,7 @@
 #define PMF_POLICY_STT_MIN					6
 #define PMF_POLICY_STT_SKINTEMP_APU				7
 #define PMF_POLICY_STT_SKINTEMP_HS2				8
+#define PMF_POLICY_SYSTEM_STATE					9
 #define PMF_POLICY_P3T						38
 
 /* TA macros */
@@ -445,6 +446,13 @@ enum smart_pc_status {
 };
 
 /* Smart PC - TA internals */
+enum system_state {
+	SYSTEM_STATE_S0i3,
+	SYSTEM_STATE_S4,
+	SYSTEM_STATE_SCREEN_LOCK,
+	SYSTEM_STATE_MAX,
+};
+
 enum ta_slider {
 	TA_BEST_BATTERY,
 	TA_BETTER_BATTERY,
@@ -476,6 +484,7 @@ enum ta_pmf_error_type {
 };
 
 struct pmf_action_table {
+	enum system_state system_state;
 	u32 spl;		/* in mW */
 	u32 sppt;		/* in mW */
 	u32 sppt_apuonly;	/* in mW */

drivers/platform/x86/amd/pmf/tee-if.c

@@ -24,6 +24,20 @@ MODULE_PARM_DESC(pb_actions_ms, "Policy binary actions sampling frequency (defau
 static const uuid_t amd_pmf_ta_uuid = UUID_INIT(0x6fd93b77, 0x3fb8, 0x524d,
 						0xb1, 0x2d, 0xc5, 0x29, 0xb1, 0x3d, 0x85, 0x43);
 
+static const char *amd_pmf_uevent_as_str(unsigned int state)
+{
+	switch (state) {
+	case SYSTEM_STATE_S0i3:
+		return "S0i3";
+	case SYSTEM_STATE_S4:
+		return "S4";
+	case SYSTEM_STATE_SCREEN_LOCK:
+		return "SCREEN_LOCK";
+	default:
+		return "Unknown Smart PC event";
+	}
+}
+
 static void amd_pmf_prepare_args(struct amd_pmf_dev *dev, int cmd,
 				 struct tee_ioctl_invoke_arg *arg,
 				 struct tee_param *param)
@@ -42,6 +56,20 @@ static void amd_pmf_prepare_args(struct amd_pmf_dev *dev, int cmd,
 	param[0].u.memref.shm_offs = 0;
 }
 
+static int amd_pmf_update_uevents(struct amd_pmf_dev *dev, u16 event)
+{
+	char *envp[2] = {};
+
+	envp[0] = kasprintf(GFP_KERNEL, "EVENT_ID=%d", event);
+	if (!envp[0])
+		return -EINVAL;
+
+	kobject_uevent_env(&dev->dev->kobj, KOBJ_CHANGE, envp);
+
+	kfree(envp[0]);
+	return 0;
+}
+
 static void amd_pmf_apply_policies(struct amd_pmf_dev *dev, struct ta_pmf_enact_result *out)
 {
 	u32 val;
@@ -113,6 +141,12 @@ static void amd_pmf_apply_policies(struct amd_pmf_dev *dev, struct ta_pmf_enact_
 				dev->prev_data->p3t_limit = val;
 			}
 			break;
+
+		case PMF_POLICY_SYSTEM_STATE:
+			amd_pmf_update_uevents(dev, val);
+			dev_dbg(dev->dev, "update SYSTEM_STATE: %s\n",
+				amd_pmf_uevent_as_str(val));
+			break;
 		}
 	}
 }