1 files changed, 281 insertions, 0 deletions
diff --git a/arch/ia64/kernel/uncached.c b/arch/ia64/kernel/uncached.c
new file mode 100644
index 000000000..20e8a9b21
--- /dev/null
+++ b/arch/ia64/kernel/uncached.c
@@ -0,0 +1,281 @@
+/*
+ * Copyright (C) 2001-2008 Silicon Graphics, Inc.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2 of the GNU General Public License
+ * as published by the Free Software Foundation.
+ *
+ * A simple uncached page allocator using the generic allocator. This
+ * allocator first utilizes the spare (spill) pages found in the EFI
+ * memmap and will then start converting cached pages to uncached ones
+ * at a granule at a time. Node awareness is implemented by having a
+ * pool of pages per node.
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/efi.h>
+#include <linux/genalloc.h>
+#include <linux/gfp.h>
+#include <asm/page.h>
+#include <asm/pal.h>
+#include <asm/pgtable.h>
+#include <linux/atomic.h>
+#include <asm/tlbflush.h>
+#include <asm/sn/arch.h>
+
+
+extern void __init efi_memmap_walk_uc(efi_freemem_callback_t, void *);
+
+struct uncached_pool {
+	struct gen_pool *pool;
+	struct mutex add_chunk_mutex;	/* serialize adding a converted chunk */
+	int nchunks_added;		/* #of converted chunks added to pool */
+	atomic_t status;		/* smp called function's return status*/
+};
+
+#define MAX_CONVERTED_CHUNKS_PER_NODE	2
+
+struct uncached_pool uncached_pools[MAX_NUMNODES];
+
+
+static void uncached_ipi_visibility(void *data)
+{
+	int status;
+	struct uncached_pool *uc_pool = (struct uncached_pool *)data;
+
+	status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL);
+	if ((status != PAL_VISIBILITY_OK) &&
+	    (status != PAL_VISIBILITY_OK_REMOTE_NEEDED))
+		atomic_inc(&uc_pool->status);
+}
+
+
+static void uncached_ipi_mc_drain(void *data)
+{
+	int status;
+	struct uncached_pool *uc_pool = (struct uncached_pool *)data;
+
+	status = ia64_pal_mc_drain();
+	if (status != PAL_STATUS_SUCCESS)
+		atomic_inc(&uc_pool->status);
+}
+
+
+/*
+ * Add a new chunk of uncached memory pages to the specified pool.
+ *
+ * @pool: pool to add new chunk of uncached memory to
+ * @nid: node id of node to allocate memory from, or -1
+ *
+ * This is accomplished by first allocating a granule of cached memory pages
+ * and then converting them to uncached memory pages.
+ */
+static int uncached_add_chunk(struct uncached_pool *uc_pool, int nid)
+{
+	struct page *page;
+	int status, i, nchunks_added = uc_pool->nchunks_added;
+	unsigned long c_addr, uc_addr;
+
+	if (mutex_lock_interruptible(&uc_pool->add_chunk_mutex) != 0)
+		return -1;	/* interrupted by a signal */
+
+	if (uc_pool->nchunks_added > nchunks_added) {
+		/* someone added a new chunk while we were waiting */
+		mutex_unlock(&uc_pool->add_chunk_mutex);
+		return 0;
+	}
+
+	if (uc_pool->nchunks_added >= MAX_CONVERTED_CHUNKS_PER_NODE) {
+		mutex_unlock(&uc_pool->add_chunk_mutex);
+		return -1;
+	}
+
+	/* attempt to allocate a granule's worth of cached memory pages */
+
+	page = alloc_pages_exact_node(nid,
+				GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE,
+				IA64_GRANULE_SHIFT-PAGE_SHIFT);
+	if (!page) {
+		mutex_unlock(&uc_pool->add_chunk_mutex);
+		return -1;
+	}
+
+	/* convert the memory pages from cached to uncached */
+
+	c_addr = (unsigned long)page_address(page);
+	uc_addr = c_addr - PAGE_OFFSET + __IA64_UNCACHED_OFFSET;
+
+	/*
+	 * There's a small race here where it's possible for someone to
+	 * access the page through /dev/mem halfway through the conversion
+	 * to uncached - not sure it's really worth bothering about
+	 */
+	for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++)
+		SetPageUncached(&page[i]);
+
+	flush_tlb_kernel_range(uc_addr, uc_addr + IA64_GRANULE_SIZE);
+
+	status = ia64_pal_prefetch_visibility(PAL_VISIBILITY_PHYSICAL);
+	if (status == PAL_VISIBILITY_OK_REMOTE_NEEDED) {
+		atomic_set(&uc_pool->status, 0);
+		status = smp_call_function(uncached_ipi_visibility, uc_pool, 1);
+		if (status || atomic_read(&uc_pool->status))
+			goto failed;
+	} else if (status != PAL_VISIBILITY_OK)
+		goto failed;
+
+	preempt_disable();
+
+	if (ia64_platform_is("sn2"))
+		sn_flush_all_caches(uc_addr, IA64_GRANULE_SIZE);
+	else
+		flush_icache_range(uc_addr, uc_addr + IA64_GRANULE_SIZE);
+
+	/* flush the just introduced uncached translation from the TLB */
+	local_flush_tlb_all();
+
+	preempt_enable();
+
+	status = ia64_pal_mc_drain();
+	if (status != PAL_STATUS_SUCCESS)
+		goto failed;
+	atomic_set(&uc_pool->status, 0);
+	status = smp_call_function(uncached_ipi_mc_drain, uc_pool, 1);
+	if (status || atomic_read(&uc_pool->status))
+		goto failed;
+
+	/*
+	 * The chunk of memory pages has been converted to uncached so now we
+	 * can add it to the pool.
+	 */
+	status = gen_pool_add(uc_pool->pool, uc_addr, IA64_GRANULE_SIZE, nid);
+	if (status)
+		goto failed;
+
+	uc_pool->nchunks_added++;
+	mutex_unlock(&uc_pool->add_chunk_mutex);
+	return 0;
+
+	/* failed to convert or add the chunk so give it back to the kernel */
+failed:
+	for (i = 0; i < (IA64_GRANULE_SIZE / PAGE_SIZE); i++)
+		ClearPageUncached(&page[i]);
+
+	free_pages(c_addr, IA64_GRANULE_SHIFT-PAGE_SHIFT);
+	mutex_unlock(&uc_pool->add_chunk_mutex);
+	return -1;
+}
+
+
+/*
+ * uncached_alloc_page
+ *
+ * @starting_nid: node id of node to start with, or -1
+ * @n_pages: number of contiguous pages to allocate
+ *
+ * Allocate the specified number of contiguous uncached pages on the
+ * the requested node. If not enough contiguous uncached pages are available
+ * on the requested node, roundrobin starting with the next higher node.
+ */
+unsigned long uncached_alloc_page(int starting_nid, int n_pages)
+{
+	unsigned long uc_addr;
+	struct uncached_pool *uc_pool;
+	int nid;
+
+	if (unlikely(starting_nid >= MAX_NUMNODES))
+		return 0;
+
+	if (starting_nid < 0)
+		starting_nid = numa_node_id();
+	nid = starting_nid;
+
+	do {
+		if (!node_state(nid, N_HIGH_MEMORY))
+			continue;
+		uc_pool = &uncached_pools[nid];
+		if (uc_pool->pool == NULL)
+			continue;
+		do {
+			uc_addr = gen_pool_alloc(uc_pool->pool,
+						 n_pages * PAGE_SIZE);
+			if (uc_addr != 0)
+				return uc_addr;
+		} while (uncached_add_chunk(uc_pool, nid) == 0);
+
+	} while ((nid = (nid + 1) % MAX_NUMNODES) != starting_nid);
+
+	return 0;
+}
+EXPORT_SYMBOL(uncached_alloc_page);
+
+
+/*
+ * uncached_free_page
+ *
+ * @uc_addr: uncached address of first page to free
+ * @n_pages: number of contiguous pages to free
+ *
+ * Free the specified number of uncached pages.
+ */
+void uncached_free_page(unsigned long uc_addr, int n_pages)
+{
+	int nid = paddr_to_nid(uc_addr - __IA64_UNCACHED_OFFSET);
+	struct gen_pool *pool = uncached_pools[nid].pool;
+
+	if (unlikely(pool == NULL))
+		return;
+
+	if ((uc_addr & (0XFUL << 60)) != __IA64_UNCACHED_OFFSET)
+		panic("uncached_free_page invalid address %lx\n", uc_addr);
+
+	gen_pool_free(pool, uc_addr, n_pages * PAGE_SIZE);
+}
+EXPORT_SYMBOL(uncached_free_page);
+
+
+/*
+ * uncached_build_memmap,
+ *
+ * @uc_start: uncached starting address of a chunk of uncached memory
+ * @uc_end: uncached ending address of a chunk of uncached memory
+ * @arg: ignored, (NULL argument passed in on call to efi_memmap_walk_uc())
+ *
+ * Called at boot time to build a map of pages that can be used for
+ * memory special operations.
+ */
+static int __init uncached_build_memmap(u64 uc_start, u64 uc_end, void *arg)
+{
+	int nid = paddr_to_nid(uc_start - __IA64_UNCACHED_OFFSET);
+	struct gen_pool *pool = uncached_pools[nid].pool;
+	size_t size = uc_end - uc_start;
+
+	touch_softlockup_watchdog();
+
+	if (pool != NULL) {
+		memset((char *)uc_start, 0, size);
+		(void) gen_pool_add(pool, uc_start, size, nid);
+	}
+	return 0;
+}
+
+
+static int __init uncached_init(void)
+{
+	int nid;
+
+	for_each_node_state(nid, N_ONLINE) {
+		uncached_pools[nid].pool = gen_pool_create(PAGE_SHIFT, nid);
+		mutex_init(&uncached_pools[nid].add_chunk_mutex);
+	}
+
+	efi_memmap_walk_uc(uncached_build_memmap, NULL);
+	return 0;
+}
+
+__initcall(uncached_init);