Simple DMA implementation. Allows for allocation of coherent memory
(simply uncached) for DMA operations.
Signed-off-by: Jonas Bonn <jonas@xxxxxxxxxxxx>
Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>
---
arch/openrisc/include/asm/dma-mapping.h | 62 ++++++++++++++
arch/openrisc/kernel/dma.c | 132 +++++++++++++++++++++++++++++++
2 files changed, 194 insertions(+), 0 deletions(-)
create mode 100644 arch/openrisc/include/asm/dma-mapping.h
create mode 100644 arch/openrisc/kernel/dma.c
diff --git a/arch/openrisc/include/asm/dma-mapping.h b/arch/openrisc/include/asm/dma-mapping.h
new file mode 100644
index 0000000..3d68ed8
--- /dev/null
+++ b/arch/openrisc/include/asm/dma-mapping.h
@@ -0,0 +1,62 @@
+/*
+ * OpenRISC Linux
+ *
+ * Linux architectural port borrowing liberally from similar works of
+ * others. All original copyrights apply as per the original source
+ * declaration.
+ *
+ * OpenRISC implementation:
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@xxxxxxxxxxxx>
+ *
+ * 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.
+ */
+
+#ifndef __ASM_OPENRISC_DMA_MAPPING_H
+#define __ASM_OPENRISC_DMA_MAPPING_H
+
+/*
+ * See Documentation/PCI/PCI-DMA-mapping.txt and
+ * Documentation/DMA-API.txt for documentation.
+ */
+
+#include <linux/dma-debug.h>
+#include <asm-generic/dma-coherent.h>
+
+#define DMA_ERROR_CODE (~(dma_addr_t)0x0)
+
+int dma_mapping_error(struct device *dev, dma_addr_t dma_addr);
+
+int dma_supported(struct device *dev, u64 mask);
+
+int dma_set_mask(struct device *dev, u64 mask);
+
+#define dma_alloc_noncoherent(d, s, h, f) dma_alloc_coherent(d, s, h, f)
+#define dma_free_noncoherent(d, s, v, h) dma_free_coherent(d, s, v, h)
+
+void *or1k_dma_alloc_coherent(struct device *dev, size_t size,
+ dma_addr_t *dma_handle, gfp_t flag);
+void or1k_dma_free_coherent(struct device *dev, size_t size, void *vaddr,
+ dma_addr_t dma_handle);
+
+static inline void *dma_alloc_coherent(struct device *dev, size_t size,
+ dma_addr_t *dma_handle, gfp_t flag)
+{
+ void *memory;
+
+ memory = or1k_dma_alloc_coherent(dev, size, dma_handle, flag);
+
+ debug_dma_alloc_coherent(dev, size, *dma_handle, memory);
+ return memory;
+}
+
+static inline void dma_free_coherent(struct device *dev, size_t size,
+ void *cpu_addr, dma_addr_t dma_handle)
+{
+ debug_dma_free_coherent(dev, size, cpu_addr, dma_handle);
+ or1k_dma_free_coherent(dev, size, cpu_addr, dma_handle);
+}
+
+#endif /* __ASM_OPENRISC_DMA_MAPPING_H */
diff --git a/arch/openrisc/kernel/dma.c b/arch/openrisc/kernel/dma.c
new file mode 100644
index 0000000..f8eb9cf
--- /dev/null
+++ b/arch/openrisc/kernel/dma.c
@@ -0,0 +1,132 @@
+/*
+ * OpenRISC Linux
+ *
+ * Linux architectural port borrowing liberally from similar works of
+ * others. All original copyrights apply as per the original source
+ * declaration.
+ *
+ * Modifications for the OpenRISC architecture:
+ * Copyright (C) 2003 Matjaz Breskvar <phoenix@xxxxxxxxx>
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@xxxxxxxxxxxx>
+ *
+ * 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.
+ *
+ * DMA mapping callbacks...
+ * As alloc_coherent is the only DMA callback being used currently, that's
+ * the only thing implemented properly. The rest need looking into...
+ */
+
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/gfp.h>
+#include <linux/dma-debug.h>
+#include <linux/io.h>
+#include <linux/vmalloc.h>
+#include <linux/sched.h>
+
+#include <asm/cpuinfo.h>
+#include <asm/spr_defs.h>
+#include <asm/tlbflush.h>
+
+static int page_set_nocache(pte_t *pte, unsigned long addr,
+ unsigned long next, struct mm_walk *walk)
+{
+ unsigned long cl;
+
+ pte_val(*pte) |= _PAGE_CI;
+
+ /*
+ * Flush the page out of the TLB so that the new page flags get
+ * picked up next time there's an access
+ */
+ flush_tlb_page(NULL, addr);
+
+ /* Flush page out of dcache */
+ for (cl = __pa(addr); cl < __pa(next); cl += cpuinfo.dcache_block_size)
+ mtspr(SPR_DCBFR, cl);
+
+ return 0;
+}
+
+static int page_clear_nocache(pte_t *pte, unsigned long addr,
+ unsigned long next, struct mm_walk *walk)
+{
+ pte_val(*pte) &= ~_PAGE_CI;
+
+ /*
+ * Flush the page out of the TLB so that the new page flags get
+ * picked up next time there's an access
+ */
+ flush_tlb_page(NULL, addr);
+
+ return 0;
+}
+
+/*
+ * Alloc "coherent" memory, which for OpenRISC means simply uncached.
+ *
+ * This function effectively just calls __get_free_pages, sets the
+ * cache-inhibit bit on those pages, and makes sure that the pages are
+ * flushed out of the cache before they are used.
+ *
+ */
+void *or1k_dma_alloc_coherent(struct device *dev, size_t size,
+ dma_addr_t *dma_handle, gfp_t gfp)
+{
+ unsigned long va;
+ void *page;
+ struct mm_walk walk = {
+ .pte_entry = page_set_nocache,
+ .mm = &init_mm
+ };
+
+ page = alloc_pages_exact(size, gfp);
+ if (!page)
+ return NULL;
+
+ /* This gives us the real physical address of the first page. */
+ *dma_handle = __pa(page);
+
+ va = (unsigned long)page;
+
+ /*
+ * We need to iterate through the pages, clearing the dcache for
+ * them and setting the cache-inhibit bit.
+ */
+ if (walk_page_range(va, va + size, &walk)) {
+ free_pages_exact(page, size);
+ return NULL;
+ }
+
+ return (void *)va;
+}
+
+void or1k_dma_free_coherent(struct device *dev, size_t size, void *vaddr,
+ dma_addr_t dma_handle)
+{
+ unsigned long va = (unsigned long)vaddr;
+ struct mm_walk walk = {
+ .pte_entry = page_clear_nocache,
+ .mm = &init_mm
+ };
+
+ /* walk_page_range shouldn't be able to fail here */
+ WARN_ON(walk_page_range(va, va + size, &walk));
+
+ free_pages_exact(vaddr, size);
+}
+
+/* Number of entries preallocated for DMA-API debugging */
+#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
+
+static int __init dma_init(void)
+{
+ dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
+
+ return 0;
+}
+
+fs_initcall(dma_init);
--
1.7.4.1
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