Add hardware memory driver, part 2.
The main purpose of hwmem is:
* To allocate buffers suitable for use with hardware. Currently
this means contiguous buffers.
* To synchronize the caches for the allocated buffers. This is
achieved by keeping track of when the CPU uses a buffer and when
other hardware uses the buffer, when we switch from CPU to other
hardware or vice versa the caches are synchronized.
* To handle sharing of allocated buffers between processes i.e.
import, export.
Hwmem is available both through a user space API and through a
kernel API.
Signed-off-by: Johan Mossberg <johan.xx.mossberg@xxxxxxxxxxxxxx>
---
drivers/misc/hwmem/cache_handler.c | 510 ++++++++++++++++++++++++++++++++++++
drivers/misc/hwmem/cache_handler.h | 61 +++++
2 files changed, 571 insertions(+), 0 deletions(-)
create mode 100644 drivers/misc/hwmem/cache_handler.c
create mode 100644 drivers/misc/hwmem/cache_handler.h
diff --git a/drivers/misc/hwmem/cache_handler.c b/drivers/misc/hwmem/cache_handler.c
new file mode 100644
index 0000000..e0ab4ee
--- /dev/null
+++ b/drivers/misc/hwmem/cache_handler.c
@@ -0,0 +1,510 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2010
+ *
+ * Cache handler
+ *
+ * Author: Johan Mossberg <johan.xx.mossberg@xxxxxxxxxxxxxx>
+ * for ST-Ericsson.
+ *
+ * License terms: GNU General Public License (GPL), version 2.
+ */
+
+#include <linux/hwmem.h>
+
+#include <asm/pgtable.h>
+
+#include <mach/dcache.h>
+
+#include "cache_handler.h"
+
+#define U32_MAX (~(u32)0)
+
+enum hwmem_alloc_flags cachi_get_cache_settings(
+ enum hwmem_alloc_flags requested_cache_settings);
+void cachi_set_pgprot_cache_options(enum hwmem_alloc_flags cache_settings,
+ pgprot_t *pgprot);
+
+static void sync_buf_pre_cpu(struct cach_buf *buf, enum hwmem_access access,
+ struct hwmem_region *region);
+static void sync_buf_post_cpu(struct cach_buf *buf,
+ enum hwmem_access next_access, struct hwmem_region *next_region);
+
+static void invalidate_cpu_cache(struct cach_buf *buf,
+ struct cach_range *range_2b_used);
+static void clean_cpu_cache(struct cach_buf *buf,
+ struct cach_range *range_2b_used);
+static void flush_cpu_cache(struct cach_buf *buf,
+ struct cach_range *range_2b_used);
+
+static void null_range(struct cach_range *range);
+static void expand_range(struct cach_range *range,
+ struct cach_range *range_2_add);
+/*
+ * Expands range to one of enclosing_range's two edges. The function will
+ * choose which of enclosing_range's edges to expand range to in such a
+ * way that the size of range is minimized. range must be located inside
+ * enclosing_range.
+ */
+static void expand_range_2_edge(struct cach_range *range,
+ struct cach_range *enclosing_range);
+static void shrink_range(struct cach_range *range,
+ struct cach_range *range_2_remove);
+static bool is_non_empty_range(struct cach_range *range);
+static void intersect_range(struct cach_range *range_1,
+ struct cach_range *range_2, struct cach_range *intersection);
+/* Align_up restrictions apply here to */
+static void align_range_up(struct cach_range *range, u32 alignment);
+static u32 range_length(struct cach_range *range);
+static void region_2_range(struct hwmem_region *region, u32 buffer_size,
+ struct cach_range *range);
+
+static void *offset_2_vaddr(struct cach_buf *buf, u32 offset);
+static u32 offset_2_paddr(struct cach_buf *buf, u32 offset);
+
+/* Saturates, might return unaligned values when that happens */
+static u32 align_up(u32 value, u32 alignment);
+static u32 align_down(u32 value, u32 alignment);
+
+/*
+ * Exported functions
+ */
+
+void cach_init_buf(struct cach_buf *buf, enum hwmem_alloc_flags cache_settings,
+ u32 size)
+{
+ buf->vstart = NULL;
+ buf->pstart = 0;
+ buf->size = size;
+
+ buf->cache_settings = cachi_get_cache_settings(cache_settings);
+}
+
+void cach_set_buf_addrs(struct cach_buf *buf, void* vaddr, u32 paddr)
+{
+ bool tmp;
+
+ buf->vstart = vaddr;
+ buf->pstart = paddr;
+
+ if (buf->cache_settings & HWMEM_ALLOC_HINT_CACHED) {
+ /*
+ * Keep whatever is in the cache. This way we avoid an
+ * unnecessary synch if CPU is the first user.
+ */
+ buf->range_in_cpu_cache.start = 0;
+ buf->range_in_cpu_cache.end = buf->size;
+ align_range_up(&buf->range_in_cpu_cache,
+ get_dcache_granularity());
+ buf->range_dirty_in_cpu_cache.start = 0;
+ buf->range_dirty_in_cpu_cache.end = buf->size;
+ align_range_up(&buf->range_dirty_in_cpu_cache,
+ get_dcache_granularity());
+ } else {
+ flush_cpu_dcache(buf->vstart, buf->pstart, buf->size, false,
+ &tmp);
+ drain_cpu_write_buf();
+
+ null_range(&buf->range_in_cpu_cache);
+ null_range(&buf->range_dirty_in_cpu_cache);
+ }
+ null_range(&buf->range_invalid_in_cpu_cache);
+}
+
+void cach_set_pgprot_cache_options(struct cach_buf *buf, pgprot_t *pgprot)
+{
+ cachi_set_pgprot_cache_options(buf->cache_settings, pgprot);
+}
+
+void cach_set_domain(struct cach_buf *buf, enum hwmem_access access,
+ enum hwmem_domain domain, struct hwmem_region *region)
+{
+ struct hwmem_region *__region;
+ struct hwmem_region full_region;
+
+ if (region != NULL) {
+ __region = region;
+ } else {
+ full_region.offset = 0;
+ full_region.count = 1;
+ full_region.start = 0;
+ full_region.end = buf->size;
+ full_region.size = buf->size;
+
+ __region = &full_region;
+ }
+
+ switch (domain) {
+ case HWMEM_DOMAIN_SYNC:
+ sync_buf_post_cpu(buf, access, __region);
+
+ break;
+
+ case HWMEM_DOMAIN_CPU:
+ sync_buf_pre_cpu(buf, access, __region);
+
+ break;
+ }
+}
+
+/*
+ * Local functions
+ */
+
+enum hwmem_alloc_flags __attribute__((weak)) cachi_get_cache_settings(
+ enum hwmem_alloc_flags requested_cache_settings)
+{
+ static const u32 CACHE_ON_FLAGS_MASK = HWMEM_ALLOC_HINT_CACHED |
+ HWMEM_ALLOC_HINT_CACHE_WB | HWMEM_ALLOC_HINT_CACHE_WT |
+ HWMEM_ALLOC_HINT_CACHE_NAOW | HWMEM_ALLOC_HINT_CACHE_AOW |
+ HWMEM_ALLOC_HINT_INNER_AND_OUTER_CACHE |
+ HWMEM_ALLOC_HINT_INNER_CACHE_ONLY;
+ /* We don't know the cache setting so we assume worst case. */
+ static const u32 CACHE_SETTING = HWMEM_ALLOC_HINT_WRITE_COMBINE |
+ HWMEM_ALLOC_HINT_CACHED | HWMEM_ALLOC_HINT_CACHE_WB |
+ HWMEM_ALLOC_HINT_CACHE_AOW |
+ HWMEM_ALLOC_HINT_INNER_AND_OUTER_CACHE;
+
+ if (requested_cache_settings & CACHE_ON_FLAGS_MASK)
+ return CACHE_SETTING;
+ else if (requested_cache_settings & HWMEM_ALLOC_HINT_WRITE_COMBINE ||
+ (requested_cache_settings & HWMEM_ALLOC_HINT_UNCACHED &&
+ !(requested_cache_settings &
+ HWMEM_ALLOC_HINT_NO_WRITE_COMBINE)))
+ return HWMEM_ALLOC_HINT_WRITE_COMBINE;
+ else if (requested_cache_settings &
+ (HWMEM_ALLOC_HINT_NO_WRITE_COMBINE |
+ HWMEM_ALLOC_HINT_UNCACHED))
+ return 0;
+ else
+ /* Nothing specified, use cached */
+ return CACHE_SETTING;
+}
+
+void __attribute__((weak)) cachi_set_pgprot_cache_options(
+ enum hwmem_alloc_flags cache_settings, pgprot_t *pgprot)
+{
+ if (cache_settings & HWMEM_ALLOC_HINT_CACHED)
+ *pgprot = *pgprot; /* To silence compiler and checkpatch */
+ else if (cache_settings & HWMEM_ALLOC_HINT_WRITE_COMBINE)
+ *pgprot = pgprot_writecombine(*pgprot);
+ else
+ *pgprot = pgprot_noncached(*pgprot);
+}
+
+bool __attribute__((weak)) speculative_data_prefetch(void)
+{
+ /* We don't know so we go with the safe alternative */
+ return true;
+}
+
+static void sync_buf_pre_cpu(struct cach_buf *buf, enum hwmem_access access,
+ struct hwmem_region *region)
+{
+ bool write = access & HWMEM_ACCESS_WRITE;
+ bool read = access & HWMEM_ACCESS_READ;
+
+ if (!write && !read)
+ return;
+
+ if (buf->cache_settings & HWMEM_ALLOC_HINT_CACHED) {
+ struct cach_range region_range;
+
+ region_2_range(region, buf->size, ®ion_range);
+
+ if (read || (write && buf->cache_settings &
+ HWMEM_ALLOC_HINT_CACHE_WB))
+ /* Perform defered invalidates */
+ invalidate_cpu_cache(buf, ®ion_range);
+ if (read || (write && buf->cache_settings &
+ HWMEM_ALLOC_HINT_CACHE_AOW))
+ expand_range(&buf->range_in_cpu_cache, ®ion_range);
+ if (write && buf->cache_settings & HWMEM_ALLOC_HINT_CACHE_WB) {
+ struct cach_range dirty_range_addition;
+
+ if (buf->cache_settings & HWMEM_ALLOC_HINT_CACHE_AOW)
+ dirty_range_addition = region_range;
+ else
+ intersect_range(&buf->range_in_cpu_cache,
+ ®ion_range, &dirty_range_addition);
+
+ expand_range(&buf->range_dirty_in_cpu_cache,
+ &dirty_range_addition);
+ }
+ }
+ if (buf->cache_settings & HWMEM_ALLOC_HINT_WRITE_COMBINE) {
+ if (write)
+ buf->in_cpu_write_buf = true;
+ }
+}
+
+static void sync_buf_post_cpu(struct cach_buf *buf,
+ enum hwmem_access next_access, struct hwmem_region *next_region)
+{
+ bool write = next_access & HWMEM_ACCESS_WRITE;
+ bool read = next_access & HWMEM_ACCESS_READ;
+ struct cach_range region_range;
+
+ if (!write && !read)
+ return;
+
+ region_2_range(next_region, buf->size, ®ion_range);
+
+ if (write) {
+ if (speculative_data_prefetch()) {
+ /* Defer invalidate */
+ struct cach_range intersection;
+
+ intersect_range(&buf->range_in_cpu_cache,
+ ®ion_range, &intersection);
+
+ expand_range(&buf->range_invalid_in_cpu_cache,
+ &intersection);
+
+ clean_cpu_cache(buf, ®ion_range);
+ } else {
+ flush_cpu_cache(buf, ®ion_range);
+ }
+ }
+ if (read)
+ clean_cpu_cache(buf, ®ion_range);
+
+ if (buf->in_cpu_write_buf) {
+ drain_cpu_write_buf();
+
+ buf->in_cpu_write_buf = false;
+ }
+}
+
+static void invalidate_cpu_cache(struct cach_buf *buf, struct cach_range *range)
+{
+ struct cach_range intersection;
+
+ intersect_range(&buf->range_invalid_in_cpu_cache, range,
+ &intersection);
+ if (is_non_empty_range(&intersection)) {
+ bool flushed_everything;
+
+ expand_range_2_edge(&intersection,
+ &buf->range_invalid_in_cpu_cache);
+
+ /*
+ * Cache handler never uses invalidate to discard data in the
+ * cache so we can use flush instead which is considerably
+ * faster for large buffers.
+ */
+ flush_cpu_dcache(
+ offset_2_vaddr(buf, intersection.start),
+ offset_2_paddr(buf, intersection.start),
+ range_length(&intersection),
+ buf->cache_settings &
+ HWMEM_ALLOC_HINT_INNER_CACHE_ONLY,
+ &flushed_everything);
+
+ if (flushed_everything) {
+ null_range(&buf->range_invalid_in_cpu_cache);
+ null_range(&buf->range_dirty_in_cpu_cache);
+ } else {
+ /*
+ * No need to shrink range_in_cpu_cache as invalidate
+ * is only used when we can't keep track of what's in
+ * the CPU cache.
+ */
+ shrink_range(&buf->range_invalid_in_cpu_cache,
+ &intersection);
+ }
+ }
+}
+
+static void clean_cpu_cache(struct cach_buf *buf, struct cach_range *range)
+{
+ struct cach_range intersection;
+
+ intersect_range(&buf->range_dirty_in_cpu_cache, range, &intersection);
+ if (is_non_empty_range(&intersection)) {
+ bool cleaned_everything;
+
+ expand_range_2_edge(&intersection,
+ &buf->range_dirty_in_cpu_cache);
+
+ clean_cpu_dcache(
+ offset_2_vaddr(buf, intersection.start),
+ offset_2_paddr(buf, intersection.start),
+ range_length(&intersection),
+ buf->cache_settings &
+ HWMEM_ALLOC_HINT_INNER_CACHE_ONLY,
+ &cleaned_everything);
+
+ if (cleaned_everything)
+ null_range(&buf->range_dirty_in_cpu_cache);
+ else
+ shrink_range(&buf->range_dirty_in_cpu_cache,
+ &intersection);
+ }
+}
+
+static void flush_cpu_cache(struct cach_buf *buf, struct cach_range *range)
+{
+ struct cach_range intersection;
+
+ intersect_range(&buf->range_in_cpu_cache, range, &intersection);
+ if (is_non_empty_range(&intersection)) {
+ bool flushed_everything;
+
+ expand_range_2_edge(&intersection, &buf->range_in_cpu_cache);
+
+ flush_cpu_dcache(
+ offset_2_vaddr(buf, intersection.start),
+ offset_2_paddr(buf, intersection.start),
+ range_length(&intersection),
+ buf->cache_settings &
+ HWMEM_ALLOC_HINT_INNER_CACHE_ONLY,
+ &flushed_everything);
+
+ if (flushed_everything) {
+ if (!speculative_data_prefetch())
+ null_range(&buf->range_in_cpu_cache);
+ null_range(&buf->range_dirty_in_cpu_cache);
+ null_range(&buf->range_invalid_in_cpu_cache);
+ } else {
+ if (!speculative_data_prefetch())
+ shrink_range(&buf->range_in_cpu_cache,
+ &intersection);
+ shrink_range(&buf->range_dirty_in_cpu_cache,
+ &intersection);
+ shrink_range(&buf->range_invalid_in_cpu_cache,
+ &intersection);
+ }
+ }
+}
+
+static void null_range(struct cach_range *range)
+{
+ range->start = U32_MAX;
+ range->end = 0;
+}
+
+static void expand_range(struct cach_range *range,
+ struct cach_range *range_2_add)
+{
+ range->start = min(range->start, range_2_add->start);
+ range->end = max(range->end, range_2_add->end);
+}
+
+/*
+ * Expands range to one of enclosing_range's two edges. The function will
+ * choose which of enclosing_range's edges to expand range to in such a
+ * way that the size of range is minimized. range must be located inside
+ * enclosing_range.
+ */
+static void expand_range_2_edge(struct cach_range *range,
+ struct cach_range *enclosing_range)
+{
+ u32 space_on_low_side = range->start - enclosing_range->start;
+ u32 space_on_high_side = enclosing_range->end - range->end;
+
+ if (space_on_low_side < space_on_high_side)
+ range->start = enclosing_range->start;
+ else
+ range->end = enclosing_range->end;
+}
+
+static void shrink_range(struct cach_range *range,
+ struct cach_range *range_2_remove)
+{
+ if (range_2_remove->start > range->start)
+ range->end = min(range->end, range_2_remove->start);
+ else
+ range->start = max(range->start, range_2_remove->end);
+
+ if (range->start >= range->end)
+ null_range(range);
+}
+
+static bool is_non_empty_range(struct cach_range *range)
+{
+ return range->end > range->start;
+}
+
+static void intersect_range(struct cach_range *range_1,
+ struct cach_range *range_2, struct cach_range *intersection)
+{
+ intersection->start = max(range_1->start, range_2->start);
+ intersection->end = min(range_1->end, range_2->end);
+
+ if (intersection->start >= intersection->end)
+ null_range(intersection);
+}
+
+/* Align_up restrictions apply here to */
+static void align_range_up(struct cach_range *range, u32 alignment)
+{
+ if (!is_non_empty_range(range))
+ return;
+
+ range->start = align_down(range->start, alignment);
+ range->end = align_up(range->end, alignment);
+}
+
+static u32 range_length(struct cach_range *range)
+{
+ if (is_non_empty_range(range))
+ return range->end - range->start;
+ else
+ return 0;
+}
+
+static void region_2_range(struct hwmem_region *region, u32 buffer_size,
+ struct cach_range *range)
+{
+ /*
+ * We don't care about invalid regions, instead we limit the region's
+ * range to the buffer's range. This should work good enough, worst
+ * case we synch the entire buffer when we get an invalid region which
+ * is acceptable.
+ */
+ range->start = region->offset + region->start;
+ range->end = min(region->offset + (region->count * region->size) -
+ (region->size - region->end), buffer_size);
+ if (range->start >= range->end) {
+ null_range(range);
+ return;
+ }
+
+ align_range_up(range, get_dcache_granularity());
+}
+
+static void *offset_2_vaddr(struct cach_buf *buf, u32 offset)
+{
+ return (void *)((u32)buf->vstart + offset);
+}
+
+static u32 offset_2_paddr(struct cach_buf *buf, u32 offset)
+{
+ return buf->pstart + offset;
+}
+
+/* Saturates, might return unaligned values when that happens */
+static u32 align_up(u32 value, u32 alignment)
+{
+ u32 remainder = value % alignment;
+ u32 value_2_add;
+
+ if (remainder == 0)
+ return value;
+
+ value_2_add = alignment - remainder;
+
+ if (value_2_add > U32_MAX - value) /* Will overflow */
+ return U32_MAX;
+
+ return value + value_2_add;
+}
+
+static u32 align_down(u32 value, u32 alignment)
+{
+ u32 remainder = value % alignment;
+ if (remainder == 0)
+ return value;
+
+ return value - remainder;
+}
diff --git a/drivers/misc/hwmem/cache_handler.h b/drivers/misc/hwmem/cache_handler.h
new file mode 100644
index 0000000..7921051
--- /dev/null
+++ b/drivers/misc/hwmem/cache_handler.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2010
+ *
+ * Cache handler
+ *
+ * Author: Johan Mossberg <johan.xx.mossberg@xxxxxxxxxxxxxx>
+ * for ST-Ericsson.
+ *
+ * License terms: GNU General Public License (GPL), version 2.
+ */
+
+/*
+ * Cache handler can not handle simultaneous execution! The caller has to
+ * ensure such a situation does not occur.
+ */
+
+#ifndef _CACHE_HANDLER_H_
+#define _CACHE_HANDLER_H_
+
+#include <linux/types.h>
+#include <linux/hwmem.h>
+
+/*
+ * To not have to double all datatypes we've used hwmem datatypes. If someone
+ * want's to use cache handler but not hwmem then we'll have to define our own
+ * datatypes.
+ */
+
+struct cach_range {
+ u32 start; /* Inclusive */
+ u32 end; /* Exclusive */
+};
+
+/*
+ * Internal, do not touch!
+ */
+struct cach_buf {
+ void *vstart;
+ u32 pstart;
+ u32 size;
+
+ /* Remaining hints are active */
+ enum hwmem_alloc_flags cache_settings;
+
+ bool in_cpu_write_buf;
+ struct cach_range range_in_cpu_cache;
+ struct cach_range range_dirty_in_cpu_cache;
+ struct cach_range range_invalid_in_cpu_cache;
+};
+
+void cach_init_buf(struct cach_buf *buf,
+ enum hwmem_alloc_flags cache_settings, u32 size);
+
+void cach_set_buf_addrs(struct cach_buf *buf, void* vaddr, u32 paddr);
+
+void cach_set_pgprot_cache_options(struct cach_buf *buf, pgprot_t *pgprot);
+
+void cach_set_domain(struct cach_buf *buf, enum hwmem_access access,
+ enum hwmem_domain domain, struct hwmem_region *region);
+
+#endif /* _CACHE_HANDLER_H_ */
--
1.7.4.1
--
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