ARM: DaVinci: IRAM alloc/free routines

This adds IRAM allocation and free routines which
will be used to fix audio underrun/overrun problems.
Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>

arch/arm/mach-davinci/Makefile

@@ -5,7 +5,7 @@
 
 # Common objects
 obj-y 			:= time.o irq.o clock.o serial.o io.o id.o psc.o \
-			   gpio.o mux.o devices.o usb.o dma.o common.o
+			   gpio.o mux.o devices.o usb.o dma.o common.o iram.o
 
 # Board specific
 obj-$(CONFIG_MACH_DAVINCI_EVM)  	+= board-evm.o

arch/arm/mach-davinci/include/mach/edma.h

@@ -560,4 +560,7 @@ void davinci_free_dma(int lch);
  * DMA channel
  **/
 void davinci_dma_getposition(int lch, dma_addr_t *src, dma_addr_t *dst);
+
+int davinci_alloc_iram(unsigned size);
+void davinci_free_iram(unsigned addr, unsigned size);
 #endif

arch/arm/mach-davinci/iram.c

+/*
+ * linux/arch/arm/mach-davinci/iram.c
+ *
+ * DaVinci iram allocation/free
+ * Copyright (C) 2008 Boundary Devices.
+ *
+ * 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 <mach/memory.h>
+
+/*
+ * 2**14 (16K) / 2**5 (32) = 2**9 (512 bytes per bit)
+ */
+static atomic_t iram_mask;
+int davinci_alloc_iram(unsigned size)
+{
+	unsigned int mask;
+	unsigned int mask_prior;
+	unsigned addr;
+	unsigned cnt;
+	cnt = (size + 511) >> 9;
+	if (cnt >= 32)
+		return 0;
+	mask = atomic_read(&iram_mask);
+	do {
+		unsigned int need_mask = (1 << cnt) - 1;
+		addr = DAVINCI_IRAM_BASE;
+		while (mask & need_mask) {
+			if (need_mask & (1<<31))
+				return -ENOMEM;
+			need_mask <<= 1;
+			addr += 512;
+		}
+		mask_prior = mask;
+		mask = atomic_cmpxchg(&iram_mask, mask, mask | need_mask);
+	} while (mask != mask_prior);
+	return addr;
+}
+EXPORT_SYMBOL(davinci_alloc_iram);
+
+void davinci_free_iram(unsigned addr, unsigned size)
+{
+	unsigned mask;
+	addr -= DAVINCI_IRAM_BASE;
+	addr >>= 9;
+	size = (size + 511) >> 9;
+	if ((size + addr) >= 32)
+		return;
+	mask = ((1 << size) - 1) << addr;
+	atomic_clear_mask(mask, (unsigned long *)&iram_mask.counter);
+}
+EXPORT_SYMBOL(davinci_free_iram);