[PATCH V8 2/4] genalloc:support memory-allocation from offset

[Zhao Qiang]

Add new algo for genalloc, it finds the first available region
from a specific offset address of memory matching the size
requirement (no alignment constraint)

Signed-off-by: Zhao Qiang <qiang.zhao@xxxxxxxxxxxxx>
---
 include/linux/genalloc.h | 11 +++++++++++
 lib/genalloc.c           | 26 ++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/include/linux/genalloc.h b/include/linux/genalloc.h
index aaf3dc2..c384791 100644
--- a/include/linux/genalloc.h
+++ b/include/linux/genalloc.h
@@ -82,6 +82,13 @@ struct genpool_data_align {
 	int align;		/* alignment by bytes for starting address */
 };
 
+/*
+ *  gen_pool data descriptor for gen_pool_first_fit_offset.
+ */
+struct genpool_data_offset {
+	unsigned long offset;		/* The offset to start searching at */
+};
+
 extern struct gen_pool *gen_pool_create(int, int);
 extern phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long);
 extern int gen_pool_add_virt(struct gen_pool *, unsigned long, phys_addr_t,
@@ -121,6 +128,10 @@ extern unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
 		unsigned long start, unsigned int nr, void *data,
 		struct gen_pool *pool);
 
+extern unsigned long gen_pool_first_fit_offset(unsigned long *map,
+		unsigned long size, unsigned long start, unsigned int nr,
+		void *data, struct gen_pool *pool);
+
 extern unsigned long gen_pool_first_fit_align(unsigned long *map,
 		unsigned long size, unsigned long start, unsigned int nr,
 		void *data, struct gen_pool *pool);
diff --git a/lib/genalloc.c b/lib/genalloc.c
index b8762b1..b4f9182 100644
--- a/lib/genalloc.c
+++ b/lib/genalloc.c
@@ -554,6 +554,32 @@ unsigned long gen_pool_first_fit_align(unsigned long *map, unsigned long size,
 EXPORT_SYMBOL(gen_pool_first_fit_align);
 
 /**
+ * gen_pool_first_fit_offset - find the first available region
+ * from a specific offset address of memory matching the size
+ * requirement (no alignment constraint)
+ * @map: The address to base the search on
+ * @size: The bitmap size in bits
+ * @start: The bitnumber to start searching at
+ * @nr: The number of zeroed bits we're looking for
+ * @data: data for alignment
+ * @pool: pool to get order from
+ */
+unsigned long gen_pool_first_fit_offset(unsigned long *map, unsigned long size,
+		unsigned long start, unsigned int nr, void *data,
+		struct gen_pool *pool)
+{
+	struct genpool_data_offset *offset_data;
+	int order;
+	unsigned long offset_bit;
+
+	offset_data = data;
+	order = pool->min_alloc_order;
+	offset_bit = (offset_data->offset + (1UL << order) - 1) >> order;
+	return bitmap_find_next_zero_area(map, size, start + offset_bit, nr, 0);
+}
+EXPORT_SYMBOL(gen_pool_first_fit_offset);
+
+/**
  * gen_pool_first_fit_order_align - find the first available region
  * of memory matching the size requirement. The region will be aligned
  * to the order of the size specified.
-- 
2.1.0.27.g96db324

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