Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 97 insertions, 0 deletions

diff --git a/arch/sh/mm/pg-dma.c b/arch/sh/mm/pg-dma.c
new file mode 100644
index 000000000000..1406d2e348ca
--- /dev/null
+++ b/arch/sh/mm/pg-dma.c
@@ -0,0 +1,97 @@
+/*
+ * arch/sh/mm/pg-dma.c
+ *
+ * Fast clear_page()/copy_page() implementation using the SH DMAC
+ *
+ * Copyright (C) 2003  Paul Mundt
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <asm/semaphore.h>
+#include <asm/mmu_context.h>
+#include <asm/addrspace.h>
+#include <asm/atomic.h>
+#include <asm/page.h>
+#include <asm/dma.h>
+#include <asm/io.h>
+
+/* Channel to use for page ops, must be dual-address mode capable. */
+static int dma_channel = CONFIG_DMA_PAGE_OPS_CHANNEL;
+
+static void copy_page_dma(void *to, void *from)
+{
+        /* 
+         * This doesn't seem to get triggered until further along in the
+         * boot process, at which point the DMAC is already initialized.
+         * Fix this in the same fashion as clear_page_dma() in the event
+         * that this crashes due to the DMAC not being initialized.
+         */
+
+        flush_icache_range((unsigned long)from, PAGE_SIZE);
+        dma_write_page(dma_channel, (unsigned long)from, (unsigned long)to);
+        dma_wait_for_completion(dma_channel);
+}
+
+static void clear_page_dma(void *to)
+{
+        extern unsigned long empty_zero_page[1024];
+
+        /*
+         * We get invoked quite early on, if the DMAC hasn't been initialized
+         * yet, fall back on the slow manual implementation.
+         */
+        if (dma_info[dma_channel].chan != dma_channel) {
+                clear_page_slow(to);
+                return;
+        }
+
+        dma_write_page(dma_channel, (unsigned long)empty_zero_page,
+                                    (unsigned long)to);
+
+        /*
+         * FIXME: Something is a bit racy here, if we poll the counter right
+         * away, we seem to lock. flushing the page from the dcache doesn't
+         * seem to make a difference one way or the other, though either a full
+         * icache or dcache flush does.
+         *
+         * The location of this is important as well, and must happen prior to
+         * the completion loop but after the transfer was initiated.
+         *
+         * Oddly enough, this doesn't appear to be an issue for copy_page()..
+         */
+        flush_icache_range((unsigned long)to, PAGE_SIZE);
+
+        dma_wait_for_completion(dma_channel);
+}
+
+static int __init pg_dma_init(void)
+{
+        int ret;
+        
+        ret = request_dma(dma_channel, "page ops");
+        if (ret != 0)
+                return ret;
+
+        copy_page = copy_page_dma;
+        clear_page = clear_page_dma;
+
+        return ret;
+}
+
+static void __exit pg_dma_exit(void)
+{
+        free_dma(dma_channel);
+}
+
+module_init(pg_dma_init);
+module_exit(pg_dma_exit);
+
+MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
+MODULE_DESCRIPTION("Optimized page copy/clear routines using a dual-address mode capable DMAC channel");
+MODULE_LICENSE("GPL");
+