msm: ion: Export msm_ion_do_cache_offset_op to do cache operations

The current API exposed to clients for doing
cache operations didn't provide option to
specify offset within ion buffer and goes
and performs operation on complete buffer.
Export new function for clients which wants to
perform cache operation on specific range
within ion buffer.

We would also need to amend the current generic
ion_do_cache_op function to correctly take into
account the offset within buffer.

Change-Id: I5e4e7beda47cbbd43783048c64fe5adb2beb7023
Signed-off-by: Susheel Khiani <skhiani@codeaurora.org>
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>

drivers/staging/android/ion/msm/msm_ion.c

@@ -157,6 +157,15 @@ int msm_ion_do_cache_op(struct ion_client *client, struct ion_handle *handle,
 }
 EXPORT_SYMBOL(msm_ion_do_cache_op);
 
+int msm_ion_do_cache_offset_op(
+		struct ion_client *client, struct ion_handle *handle,
+		void *vaddr, unsigned int offset, unsigned long len,
+		unsigned int cmd)
+{
+	return ion_do_cache_op(client, handle, vaddr, offset, len, cmd);
+}
+EXPORT_SYMBOL(msm_ion_do_cache_offset_op);
+
 static int ion_no_pages_cache_ops(struct ion_client *client,
 			struct ion_handle *handle,
 			void *vaddr,
@@ -305,13 +314,23 @@ static int ion_pages_cache_ops(struct ion_client *client,
 	};
 
 	for_each_sg(table->sgl, sg, table->nents, i) {
+		unsigned int sg_offset, sg_left, size = 0;
+
 		len += sg->length;
-		if (len < offset)
+		if (len <= offset)
 			continue;
 
-		__do_cache_ops(sg_page(sg), sg->offset, sg->length, op);
+		sg_left = len - offset;
+		sg_offset = sg->length - sg_left;
 
-		if (len > length + offset)
+		size = (length < sg_left) ? length : sg_left;
+
+		__do_cache_ops(sg_page(sg), sg_offset, size, op);
+
+		offset += size;
+		length -= size;
+
+		if (length == 0)
 			break;
 	}
 	return 0;

drivers/staging/android/ion/msm/msm_ion.h

@@ -1,3 +1,16 @@
+/*
+ * Copyright (c) 2016, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
 #ifndef _MSM_MSM_ION_H
 #define _MSM_MSM_ION_H
 
@@ -157,6 +170,11 @@ int ion_handle_get_size(struct ion_client *client, struct ion_handle *handle,
 int msm_ion_do_cache_op(struct ion_client *client, struct ion_handle *handle,
 			void *vaddr, unsigned long len, unsigned int cmd);
 
+int msm_ion_do_cache_offset_op(
+		struct ion_client *client, struct ion_handle *handle,
+		void *vaddr, unsigned int offset, unsigned long len,
+		unsigned int cmd);
+
 #else
 static inline struct ion_client *msm_ion_client_create(const char *name)
 {
@@ -176,6 +194,14 @@ static inline int msm_ion_do_cache_op(struct ion_client *client,
 	return -ENODEV;
 }
 
+int msm_ion_do_cache_offset_op(
+		struct ion_client *client, struct ion_handle *handle,
+		void *vaddr, unsigned int offset, unsigned long len,
+		unsigned int cmd)
+{
+	return -ENODEV;
+}
+
 #endif /* CONFIG_ION */
 
 #endif