[PATCH v2 1/4] drm/komeda: Introduce komeda_coeffs_table/manager

[james qian wang (Arm Technology China)]

komeda display HWs have kinds of coefficient tables for various purposes
like gamma/degamma. ususally these tables are shared by multiple HW
component and have limited number.
Introduce komeda_coeffs_table/manager for describing and managing these
tables, like table reuse, racing.

Signed-off-by: James Qian Wang (Arm Technology China) <james.qian.wang@xxxxxxx>
---
 drivers/gpu/drm/arm/display/komeda/Makefile   |   1 +
 .../drm/arm/display/komeda/komeda_coeffs.c    | 119 ++++++++++++++++++
 .../drm/arm/display/komeda/komeda_coeffs.h    |  74 +++++++++++
 3 files changed, 194 insertions(+)
 create mode 100644 drivers/gpu/drm/arm/display/komeda/komeda_coeffs.c
 create mode 100644 drivers/gpu/drm/arm/display/komeda/komeda_coeffs.h

diff --git a/drivers/gpu/drm/arm/display/komeda/Makefile b/drivers/gpu/drm/arm/display/komeda/Makefile
index 5c3900c2e764..38aa5843c03a 100644
--- a/drivers/gpu/drm/arm/display/komeda/Makefile
+++ b/drivers/gpu/drm/arm/display/komeda/Makefile
@@ -8,6 +8,7 @@ komeda-y := \
 	komeda_drv.o \
 	komeda_dev.o \
 	komeda_format_caps.o \
+	komeda_coeffs.o \
 	komeda_color_mgmt.o \
 	komeda_pipeline.o \
 	komeda_pipeline_state.o \
diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_coeffs.c b/drivers/gpu/drm/arm/display/komeda/komeda_coeffs.c
new file mode 100644
index 000000000000..d9d35e23003c
--- /dev/null
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_coeffs.c
@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * (C) COPYRIGHT 2019 ARM Limited. All rights reserved.
+ * Author: James.Qian.Wang <james.qian.wang@xxxxxxx>
+ *
+ */
+#include <linux/slab.h>
+#include "komeda_coeffs.h"
+
+static inline bool is_table_in_using(struct komeda_coeffs_table *table)
+{
+	return refcount_read(&table->refcount) > 1;
+}
+
+/* request a coeffs table for the coeffs data specified by argument coeffs */
+struct komeda_coeffs_table *
+komeda_coeffs_request(struct komeda_coeffs_manager *mgr, void *coeffs)
+{
+	struct komeda_coeffs_table *table;
+	u32 i;
+
+	mutex_lock(&mgr->mutex);
+
+	/* search table list to find if there is a in-using table with the
+	 * same coefficient content, if find, reuse this table.
+	 */
+	for (i = 0; i < mgr->n_tables; i++) {
+		table = mgr->tables[i];
+
+		/* skip the unused table */
+		if (!is_table_in_using(table))
+			continue;
+
+		if (!memcmp(table->coeffs, coeffs, mgr->coeffs_sz))
+			goto found;
+	}
+
+	/* can not reuse the existing in-using table, loop for a new one */
+	for (i = 0; i < mgr->n_tables; i++) {
+		table = mgr->tables[i];
+
+		if (!is_table_in_using(table)) {
+			memcpy(table->coeffs, coeffs, mgr->coeffs_sz);
+			table->needs_update = true;
+			goto found;
+		}
+	}
+
+	/* Since previous two search loop will directly goto found if found an
+	 * available table, so once program ran here means search failed.
+	 * clear the table to NULL, unlock(mgr->mutex) and return NULL.
+	 */
+	table = NULL;
+
+found:
+	komeda_coeffs_get(table);
+	mutex_unlock(&mgr->mutex);
+	return table;
+}
+
+/* Add a coeffs table to manager */
+int komeda_coeffs_add(struct komeda_coeffs_manager *mgr,
+		      u32 hw_id, u32 __iomem *reg,
+		      void (*update)(struct komeda_coeffs_table *table))
+{
+	struct komeda_coeffs_table *table;
+
+	if (mgr->n_tables >= ARRAY_SIZE(mgr->tables))
+		return -ENOSPC;
+
+	table = kzalloc(sizeof(*table), GFP_KERNEL);
+	if (!table)
+		return -ENOMEM;
+
+	table->coeffs = kzalloc(mgr->coeffs_sz, GFP_KERNEL);
+	if (!table->coeffs) {
+		kfree(table);
+		return -ENOMEM;
+	}
+
+	refcount_set(&table->refcount, 1);
+	table->mgr = mgr;
+	table->hw_id = hw_id;
+	table->update = update;
+	table->reg = reg;
+
+	mgr->tables[mgr->n_tables++] = table;
+	return 0;
+}
+
+struct komeda_coeffs_manager *komeda_coeffs_create_manager(u32 coeffs_sz)
+{
+	struct komeda_coeffs_manager *mgr;
+
+	mgr = kzalloc(sizeof(*mgr), GFP_KERNEL);
+	if (!mgr)
+		return ERR_PTR(-ENOMEM);
+
+	mutex_init(&mgr->mutex);
+	mgr->coeffs_sz = coeffs_sz;
+
+	return mgr;
+}
+
+void komeda_coeffs_destroy_manager(struct komeda_coeffs_manager *mgr)
+{
+	u32 i;
+
+	if (!mgr)
+		return;
+
+	for (i = 0; i < mgr->n_tables; i++) {
+		WARN_ON(is_table_in_using(mgr->tables[i]));
+		kfree(mgr->tables[i]->coeffs);
+		kfree(mgr->tables[i]);
+	}
+
+	kfree(mgr);
+}
diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_coeffs.h b/drivers/gpu/drm/arm/display/komeda/komeda_coeffs.h
new file mode 100644
index 000000000000..172ac2ea17ba
--- /dev/null
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_coeffs.h
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * (C) COPYRIGHT 2019 ARM Limited. All rights reserved.
+ * Author: James.Qian.Wang <james.qian.wang@xxxxxxx>
+ *
+ */
+#ifndef _KOMEDA_COEFFS_H_
+#define _KOMEDA_COEFFS_H_
+
+#include <linux/refcount.h>
+
+/* Komeda display HWs have kinds of coefficient tables for various purposes,
+ * like gamma/degamma. ususally these tables are shared by multiple HW component
+ * and limited number.
+ * The komeda_coeffs_table/manager are imported for describing and managing
+ * these tables for table reuse and racing.
+ */
+struct komeda_coeffs_table {
+	struct komeda_coeffs_manager *mgr;
+	refcount_t refcount;
+	bool needs_update;
+	u32 hw_id;
+	void *coeffs;
+	u32 __iomem *reg;
+	void (*update)(struct komeda_coeffs_table *table);
+};
+
+struct komeda_coeffs_manager {
+	struct mutex mutex; /* for tables accessing */
+	u32 n_tables;
+	u32 coeffs_sz;
+	struct komeda_coeffs_table *tables[8];
+};
+
+static inline struct komeda_coeffs_table *
+komeda_coeffs_get(struct komeda_coeffs_table *table)
+{
+	if (table)
+		refcount_inc(&table->refcount);
+
+	return table;
+}
+
+static inline void __komeda_coeffs_put(struct komeda_coeffs_table *table)
+{
+	if (table)
+		refcount_dec(&table->refcount);
+}
+
+#define komeda_coeffs_put(table) \
+do { \
+	__komeda_coeffs_put(table); \
+	(table) = NULL; \
+} while (0)
+
+static inline void komeda_coeffs_update(struct komeda_coeffs_table *table)
+{
+	if (!table || !table->needs_update)
+		return;
+
+	table->update(table);
+	table->needs_update = false;
+}
+
+struct komeda_coeffs_manager *komeda_coeffs_create_manager(u32 coeffs_sz);
+void komeda_coeffs_destroy_manager(struct komeda_coeffs_manager *mgr);
+
+int komeda_coeffs_add(struct komeda_coeffs_manager *mgr,
+		      u32 hw_id, u32 __iomem *reg,
+		      void (*update)(struct komeda_coeffs_table *table));
+struct komeda_coeffs_table *
+komeda_coeffs_request(struct komeda_coeffs_manager *mgr, void *coeffs);
+
+#endif /*_KOMEDA_COEFFS_H_*/
-- 
2.20.1