1 files changed, 74 insertions, 0 deletions

diff --git a/sound/firewire/packets-buffer.c b/sound/firewire/packets-buffer.c
new file mode 100644
index 000000000000..1e20e60ba6a6
--- /dev/null
+++ b/sound/firewire/packets-buffer.c
@@ -0,0 +1,74 @@
+/*
+ * helpers for managing a buffer for many packets
+ *
+ * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
+ * Licensed under the terms of the GNU General Public License, version 2.
+ */
+
+#include <linux/firewire.h>
+#include <linux/slab.h>
+#include "packets-buffer.h"
+
+/**
+ * iso_packets_buffer_init - allocates the memory for packets
+ * @b: the buffer structure to initialize
+ * @unit: the device at the other end of the stream
+ * @count: the number of packets
+ * @packet_size: the (maximum) size of a packet, in bytes
+ * @direction: %DMA_TO_DEVICE or %DMA_FROM_DEVICE
+ */
+int iso_packets_buffer_init(struct iso_packets_buffer *b, struct fw_unit *unit,
+                            unsigned int count, unsigned int packet_size,
+                            enum dma_data_direction direction)
+{
+        unsigned int packets_per_page, pages;
+        unsigned int i, page_index, offset_in_page;
+        void *p;
+        int err;
+
+        b->packets = kmalloc(count * sizeof(*b->packets), GFP_KERNEL);
+        if (!b->packets) {
+                err = -ENOMEM;
+                goto error;
+        }
+
+        packet_size = L1_CACHE_ALIGN(packet_size);
+        packets_per_page = PAGE_SIZE / packet_size;
+        if (WARN_ON(!packets_per_page)) {
+                err = -EINVAL;
+                goto error;
+        }
+        pages = DIV_ROUND_UP(count, packets_per_page);
+
+        err = fw_iso_buffer_init(&b->iso_buffer, fw_parent_device(unit)->card,
+                                 pages, direction);
+        if (err < 0)
+                goto err_packets;
+
+        for (i = 0; i < count; ++i) {
+                page_index = i / packets_per_page;
+                p = page_address(b->iso_buffer.pages[page_index]);
+                offset_in_page = (i % packets_per_page) * packet_size;
+                b->packets[i].buffer = p + offset_in_page;
+                b->packets[i].offset = page_index * PAGE_SIZE + offset_in_page;
+        }
+
+        return 0;
+
+err_packets:
+        kfree(b->packets);
+error:
+        return err;
+}
+
+/**
+ * iso_packets_buffer_destroy - frees packet buffer resources
+ * @b: the buffer structure to free
+ * @unit: the device at the other end of the stream
+ */
+void iso_packets_buffer_destroy(struct iso_packets_buffer *b,
+                                struct fw_unit *unit)
+{
+        fw_iso_buffer_destroy(&b->iso_buffer, fw_parent_device(unit)->card);
+        kfree(b->packets);
+}