drm/xe/guc: Add SLPC power profile interface

GuC has an interface to set a power profile for the SLPC algorithm.
Base mode is default and ensures a balanced performance, power_saving
mode has conservative up/down thresholds and is suitable for use with
apps that typically need to be power efficient. This will result in
lower GT frequencies, thus consuming lower power.

Selected power profile will be displayed in this format:

$ cat power_profile

[base] power_saving

$ echo power_saving > power_profile
$ cat power_profile

base [power_saving]

v2: Address review comments (Rodrigo)

Cc: Rodrigo Vivi <[e-mail]>
Signed-off-by: Vinay Belgaumkar <[e-mail]>
Reviewed-by: Rodrigo Vivi <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Rodrigo Vivi <[e-mail]>

drivers/gpu/drm/xe/abi/guc_actions_slpc_abi.h

···
 	u8 reserved_mode_definition[4096];
 } __packed;
 
+enum slpc_power_profile {
+	SLPC_POWER_PROFILE_BASE = 0x0,
+	SLPC_POWER_PROFILE_POWER_SAVING = 0x1
+};
+
 /**
  * DOC: SLPC H2G MESSAGE FORMAT
  *

drivers/gpu/drm/xe/xe_gt_freq.c

···
 }
 static struct kobj_attribute attr_max_freq = __ATTR_RW(max_freq);
 
+static ssize_t power_profile_show(struct kobject *kobj,
+				  struct kobj_attribute *attr,
+				  char *buff)
+{
+	struct device *dev = kobj_to_dev(kobj);
+
+	xe_guc_pc_get_power_profile(dev_to_pc(dev), buff);
+
+	return strlen(buff);
+}
+
+static ssize_t power_profile_store(struct kobject *kobj,
+				   struct kobj_attribute *attr,
+				   const char *buff, size_t count)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct xe_guc_pc *pc = dev_to_pc(dev);
+	int err;
+
+	err = xe_guc_pc_set_power_profile(pc, buff);
+
+	return err ?: count;
+}
+static struct kobj_attribute attr_power_profile = __ATTR_RW(power_profile);
+
 static const struct attribute *freq_attrs[] = {
 	&attr_act_freq.attr,
 	&attr_cur_freq.attr,
···
 	&attr_rpn_freq.attr,
 	&attr_min_freq.attr,
 	&attr_max_freq.attr,
+	&attr_power_profile.attr,
 	NULL
 };
 

drivers/gpu/drm/xe/xe_guc_pc.c

···
  * Xe driver enables SLPC with all of its defaults features and frequency
  * selection, which varies per platform.
  *
+ * Power profiles add another level of control to SLPC. When power saving
+ * profile is chosen, SLPC will use conservative thresholds to ramp frequency,
+ * thus saving power. Base profile is default and ensures balanced performance
+ * for any workload.
+ *
  * Render-C States:
  * ================
  *
···
 	return ret;
 }
 
+static const char *power_profile_to_string(struct xe_guc_pc *pc)
+{
+	switch (pc->power_profile) {
+	case SLPC_POWER_PROFILE_BASE:
+		return "base";
+	case SLPC_POWER_PROFILE_POWER_SAVING:
+		return "power_saving";
+	default:
+		return "invalid";
+	}
+}
+
+void xe_guc_pc_get_power_profile(struct xe_guc_pc *pc, char *profile)
+{
+	switch (pc->power_profile) {
+	case SLPC_POWER_PROFILE_BASE:
+		sprintf(profile, "[%s]    %s\n", "base", "power_saving");
+		break;
+	case SLPC_POWER_PROFILE_POWER_SAVING:
+		sprintf(profile, "%s    [%s]\n", "base", "power_saving");
+		break;
+	default:
+		sprintf(profile, "invalid");
+	}
+}
+
+int xe_guc_pc_set_power_profile(struct xe_guc_pc *pc, const char *buf)
+{
+	int ret = 0;
+	u32 val;
+
+	if (strncmp("base", buf, strlen("base")) == 0)
+		val = SLPC_POWER_PROFILE_BASE;
+	else if (strncmp("power_saving", buf, strlen("power_saving")) == 0)
+		val = SLPC_POWER_PROFILE_POWER_SAVING;
+	else
+		return -EINVAL;
+
+	guard(mutex)(&pc->freq_lock);
+	xe_pm_runtime_get(pc_to_xe(pc));
+
+	ret = pc_action_set_param(pc,
+				  SLPC_PARAM_POWER_PROFILE,
+				  val);
+	if (ret)
+		xe_gt_err_once(pc_to_gt(pc), "Failed to set power profile to %d: %pe\n",
+			       val, ERR_PTR(ret));
+	else
+		pc->power_profile = val;
+
+	xe_pm_runtime_put(pc_to_xe(pc));
+
+	return ret;
+}
+
 /**
  * xe_guc_pc_start - Start GuC's Power Conservation component
  * @pc: Xe_GuC_PC instance
···
 	/* Enable SLPC Optimized Strategy for compute */
 	ret = pc_action_set_strategy(pc, SLPC_OPTIMIZED_STRATEGY_COMPUTE);
 
+	/* Set cached value of power_profile */
+	ret = xe_guc_pc_set_power_profile(pc, power_profile_to_string(pc));
+	if (unlikely(ret))
+		xe_gt_err(gt, "Failed to set SLPC power profile: %pe\n", ERR_PTR(ret));
+
 out:
 	xe_force_wake_put(gt_to_fw(gt), fw_ref);
 	return ret;
···
 		return PTR_ERR(bo);
 
 	pc->bo = bo;
+
+	pc->power_profile = SLPC_POWER_PROFILE_BASE;
 
 	return devm_add_action_or_reset(xe->drm.dev, xe_guc_pc_fini_hw, pc);
 }

drivers/gpu/drm/xe/xe_guc_pc.h

···
 int xe_guc_pc_set_min_freq(struct xe_guc_pc *pc, u32 freq);
 int xe_guc_pc_get_max_freq(struct xe_guc_pc *pc, u32 *freq);
 int xe_guc_pc_set_max_freq(struct xe_guc_pc *pc, u32 freq);
+int xe_guc_pc_set_power_profile(struct xe_guc_pc *pc, const char *buf);
+void xe_guc_pc_get_power_profile(struct xe_guc_pc *pc, char *profile);
 
 enum xe_gt_idle_state xe_guc_pc_c_status(struct xe_guc_pc *pc);
 u64 xe_guc_pc_rc6_residency(struct xe_guc_pc *pc);

drivers/gpu/drm/xe/xe_guc_pc_types.h

···
 	struct mutex freq_lock;
 	/** @freq_ready: Only handle freq changes, if they are really ready */
 	bool freq_ready;
+	/** @power_profile: Base or power_saving profile */
+	u32 power_profile;
 };
 
 #endif	/* _XE_GUC_PC_TYPES_H_ */