davinci: add SRAM allocator

Provide a generic SRAM allocator using genalloc, and vaguely
modeled after what AVR32 uses.  This builds on top of the
static CPU mapping set up in the previous patch, and returns
DMA mappings as requested (if possible).

Compared to its OMAP cousin, there's no current support for
(currently non-existent) DaVinci power management code running
in SRAM; and this has ways to deallocate, instead of being
allocate-only.

The initial user of this should probably be the audio code,
because EDMA from DDR is subject to various dropouts on at
least DM355 and DM6446 chips.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

1 files changed, 74 insertions, 0 deletions

diff --git a/arch/arm/mach-davinci/sram.c b/arch/arm/mach-davinci/sram.c
new file mode 100644
index 000000000000..db54b2a66b4d
--- /dev/null
+++ b/arch/arm/mach-davinci/sram.c
@@ -0,0 +1,74 @@
+/*
+ * mach-davinci/sram.c - DaVinci simple SRAM allocator
+ *
+ * Copyright (C) 2009 David Brownell
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/genalloc.h>
+
+#include <mach/common.h>
+#include <mach/memory.h>
+#include <mach/sram.h>
+
+
+static struct gen_pool *sram_pool;
+
+void *sram_alloc(size_t len, dma_addr_t *dma)
+{
+        unsigned long vaddr;
+        dma_addr_t dma_base = davinci_soc_info.sram_dma;
+
+        if (dma)
+                *dma = 0;
+        if (!sram_pool || (dma && !dma_base))
+                return NULL;
+
+        vaddr = gen_pool_alloc(sram_pool, len);
+        if (!vaddr)
+                return NULL;
+
+        if (dma)
+                *dma = dma_base + (vaddr - SRAM_VIRT);
+        return (void *)vaddr;
+
+}
+EXPORT_SYMBOL(sram_alloc);
+
+void sram_free(void *addr, size_t len)
+{
+        gen_pool_free(sram_pool, (unsigned long) addr, len);
+}
+EXPORT_SYMBOL(sram_free);
+
+
+/*
+ * REVISIT This supports CPU and DMA access to/from SRAM, but it
+ * doesn't (yet?) support some other notable uses of SRAM:  as TCM
+ * for data and/or instructions; and holding code needed to enter
+ * and exit suspend states (while DRAM can't be used).
+ */
+static int __init sram_init(void)
+{
+        unsigned len = davinci_soc_info.sram_len;
+        int status = 0;
+
+        if (len) {
+                len = min(len, SRAM_SIZE);
+                sram_pool = gen_pool_create(ilog2(SRAM_GRANULARITY), -1);
+                if (!sram_pool)
+                        status = -ENOMEM;
+        }
+        if (sram_pool)
+                status = gen_pool_add(sram_pool, SRAM_VIRT, len, -1);
+        WARN_ON(status < 0);
+        return status;
+}
+core_initcall(sram_init);
+