From b088da030362ae3e4437f8eb900e007c99750566 Mon Sep 17 00:00:00 2001
From: Michal Wajdeczko <michal.wajdeczko@intel.com>
Date: Wed, 8 Jul 2026 00:08:07 +0200
Subject: [PATCH] drm/xe/guc: Add object KLV encoding helper
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We plan to encode larger objects as single KLV or set of KLVs.
Add helper for that.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
Link: https://patch.msgid.link/20260707220816.677-6-michal.wajdeczko@intel.com
---
 drivers/gpu/drm/xe/xe_guc_klv_helpers.c | 39 +++++++++++++++++++++++++
 drivers/gpu/drm/xe/xe_guc_klv_helpers.h |  2 ++
 2 files changed, 41 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_guc_klv_helpers.c b/drivers/gpu/drm/xe/xe_guc_klv_helpers.c
index fa5590b23ba0..54d977252431 100644
--- a/drivers/gpu/drm/xe/xe_guc_klv_helpers.c
+++ b/drivers/gpu/drm/xe/xe_guc_klv_helpers.c
@@ -280,3 +280,42 @@ u32 *xe_guc_klv_encode_string(u32 *klvs, u32 avail, u16 key, const char *s)
 	strscpy_pad((void *)klvs, s, to_num_bytes(len));
 	return klvs + len;
 }
+
+/**
+ * xe_guc_klv_encode_object() - Encode object using custom encoder as single KLV.
+ * @klvs: the buffer where to place KLV
+ * @avail: number of dwords (u32) available in the buffer
+ * @key: key to be used
+ * @obj: opaque object pointer
+ * @encoder: function pointer to the custom encoder
+ *
+ * Return: pointer to the buffer location past the encoded KLV or
+ *         an ERR_PTR if there was no space to encode the KLV.
+ */
+u32 *xe_guc_klv_encode_object(u32 *klvs, u32 avail, u16 key, const void *obj,
+			      u32 *(*encoder)(u32 *klvs, u32 avail, const void *obj))
+{
+	u32 *end;
+
+	if (IS_ERR(klvs))
+		return klvs;
+
+	if (avail < GUC_KLV_LEN_MIN)
+		return ERR_PTR(-ENOSPC);
+
+	if (avail > GUC_KLV_LEN_MIN + FIELD_MAX(GUC_KLV_0_LEN))
+		avail = GUC_KLV_LEN_MIN + FIELD_MAX(GUC_KLV_0_LEN);
+
+	end = encoder(klvs + GUC_KLV_LEN_MIN, avail - GUC_KLV_LEN_MIN, obj);
+	if (IS_ERR(end))
+		return end;
+
+	if (WARN_ON(end < klvs + GUC_KLV_LEN_MIN))
+		return ERR_PTR(-EPIPE);
+
+	if (WARN_ON(end > klvs + avail))
+		return ERR_PTR(-EFBIG);
+
+	*klvs = PREP_GUC_KLV(key, end - (klvs + GUC_KLV_LEN_MIN));
+	return end;
+}
diff --git a/drivers/gpu/drm/xe/xe_guc_klv_helpers.h b/drivers/gpu/drm/xe/xe_guc_klv_helpers.h
index 1c576456efc5..855805f4463d 100644
--- a/drivers/gpu/drm/xe/xe_guc_klv_helpers.h
+++ b/drivers/gpu/drm/xe/xe_guc_klv_helpers.h
@@ -20,6 +20,8 @@ int xe_guc_klv_count(const u32 *klvs, u32 num_dwords);
 u32 *xe_guc_klv_encode_u32(u32 *klvs, u32 avail, u16 key, u32 value);
 u32 *xe_guc_klv_encode_u64(u32 *klvs, u32 avail, u16 key, u64 value);
 u32 *xe_guc_klv_encode_string(u32 *klvs, u32 avail, u16 key, const char *s);
+u32 *xe_guc_klv_encode_object(u32 *klvs, u32 avail, u16 key, const void *obj,
+			      u32 *(*encoder)(u32 *klvs, u32 avail, const void *obj));
 
 /**
  * PREP_GUC_KLV - Prepare KLV header value based on provided key and len.