1 files changed, 125 insertions, 0 deletions
diff --git a/arch/openrisc/kernel/dma.c b/arch/openrisc/kernel/dma.c
new file mode 100644
index 000000000..b3edbb33b
--- /dev/null
+++ b/arch/openrisc/kernel/dma.c
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * 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@bsemi.com>
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
+ *
+ * DMA mapping callbacks...
+ */
+
+#include <linux/dma-map-ops.h>
+#include <linux/pagewalk.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;
+	struct cpuinfo_or1k *cpuinfo = &cpuinfo_or1k[smp_processor_id()];
+
+	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_kernel_range(addr, addr + PAGE_SIZE);
+
+	/* Flush page out of dcache */
+	for (cl = __pa(addr); cl < __pa(next); cl += cpuinfo->dcache_block_size)
+		mtspr(SPR_DCBFR, cl);
+
+	return 0;
+}
+
+static const struct mm_walk_ops set_nocache_walk_ops = {
+	.pte_entry		= page_set_nocache,
+};
+
+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_kernel_range(addr, addr + PAGE_SIZE);
+
+	return 0;
+}
+
+static const struct mm_walk_ops clear_nocache_walk_ops = {
+	.pte_entry		= page_clear_nocache,
+};
+
+void *arch_dma_set_uncached(void *cpu_addr, size_t size)
+{
+	unsigned long va = (unsigned long)cpu_addr;
+	int error;
+
+	/*
+	 * We need to iterate through the pages, clearing the dcache for
+	 * them and setting the cache-inhibit bit.
+	 */
+	mmap_write_lock(&init_mm);
+	error = walk_page_range_novma(&init_mm, va, va + size,
+			&set_nocache_walk_ops, NULL, NULL);
+	mmap_write_unlock(&init_mm);
+
+	if (error)
+		return ERR_PTR(error);
+	return cpu_addr;
+}
+
+void arch_dma_clear_uncached(void *cpu_addr, size_t size)
+{
+	unsigned long va = (unsigned long)cpu_addr;
+
+	mmap_write_lock(&init_mm);
+	/* walk_page_range shouldn't be able to fail here */
+	WARN_ON(walk_page_range_novma(&init_mm, va, va + size,
+			&clear_nocache_walk_ops, NULL, NULL));
+	mmap_write_unlock(&init_mm);
+}
+
+void arch_sync_dma_for_device(phys_addr_t addr, size_t size,
+		enum dma_data_direction dir)
+{
+	unsigned long cl;
+	struct cpuinfo_or1k *cpuinfo = &cpuinfo_or1k[smp_processor_id()];
+
+	switch (dir) {
+	case DMA_TO_DEVICE:
+		/* Flush the dcache for the requested range */
+		for (cl = addr; cl < addr + size;
+		     cl += cpuinfo->dcache_block_size)
+			mtspr(SPR_DCBFR, cl);
+		break;
+	case DMA_FROM_DEVICE:
+		/* Invalidate the dcache for the requested range */
+		for (cl = addr; cl < addr + size;
+		     cl += cpuinfo->dcache_block_size)
+			mtspr(SPR_DCBIR, cl);
+		break;
+	default:
+		/*
+		 * NOTE: If dir == DMA_BIDIRECTIONAL then there's no need to
+		 * flush nor invalidate the cache here as the area will need
+		 * to be manually synced anyway.
+		 */
+		break;
+	}
+}