[PATCH V6 17/25] MIPS: BMIPS: Rewrite DMA code to use "dma-ranges" property

[Kevin Cernekee <cernekee-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

This is a more standardized way of handling DMA remapping, and it is
suitable for the memory map found on BCM3384.

Signed-off-by: Kevin Cernekee <cernekee-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 arch/mips/bmips/dma.c | 100 ++++++++++++++++++++++++++++++++++----------------
 1 file changed, 68 insertions(+), 32 deletions(-)

diff --git a/arch/mips/bmips/dma.c b/arch/mips/bmips/dma.c
index ea42012..04790f4 100644
--- a/arch/mips/bmips/dma.c
+++ b/arch/mips/bmips/dma.c
@@ -6,76 +6,112 @@
  * Copyright (C) 2014 Kevin Cernekee <cernekee-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
  */
 
+#define pr_fmt(fmt)		"bmips-dma: " fmt
+
 #include <linux/device.h>
 #include <linux/dma-direction.h>
 #include <linux/dma-mapping.h>
 #include <linux/init.h>
-#include <linux/mm.h>
+#include <linux/io.h>
 #include <linux/of.h>
-#include <linux/pci.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
 #include <linux/types.h>
 #include <dma-coherence.h>
 
 /*
- * BCM3384 has configurable address translation windows which allow the
+ * BCM338x has configurable address translation windows which allow the
  * peripherals' DMA addresses to be different from the Zephyr-visible
  * physical addresses.  e.g. usb_dma_addr = zephyr_pa ^ 0x08000000
  *
- * If our DT "memory" node has a "dma-xor-mask" property we will enable this
- * translation using the provided offset.
+ * If the "brcm,ubus" node has a "dma-ranges" property we will enable this
+ * translation globally using the provided information.  This implements a
+ * very limited subset of "dma-ranges" support and it will probably be
+ * replaced by a more generic version later.
  */
-static u32 bcm3384_dma_xor_mask;
-static u32 bcm3384_dma_xor_limit = 0xffffffff;
 
-/*
- * PCI collapses the memory hole at 0x10000000 - 0x1fffffff.
- * On systems with a dma-xor-mask, this range is guaranteed to live above
- * the dma-xor-limit.
- */
-#define BCM3384_MEM_HOLE_PA	0x10000000
-#define BCM3384_MEM_HOLE_SIZE	0x10000000
+struct bmips_dma_range {
+	u32			child_addr;
+	u32			parent_addr;
+	u32			size;
+};
 
-static dma_addr_t bcm3384_phys_to_dma(struct device *dev, phys_addr_t pa)
+static struct bmips_dma_range *bmips_dma_ranges;
+
+#define FLUSH_RAC		0x100
+
+static dma_addr_t bmips_phys_to_dma(struct device *dev, phys_addr_t pa)
 {
-	if (dev && dev_is_pci(dev) &&
-	    pa >= (BCM3384_MEM_HOLE_PA + BCM3384_MEM_HOLE_SIZE))
-		return pa - BCM3384_MEM_HOLE_SIZE;
-	if (pa <= bcm3384_dma_xor_limit)
-		return pa ^ bcm3384_dma_xor_mask;
+	struct bmips_dma_range *r;
+
+	for (r = bmips_dma_ranges; r && r->size; r++) {
+		if (pa >= r->child_addr &&
+		    pa < (r->child_addr + r->size))
+			return pa - r->child_addr + r->parent_addr;
+	}
 	return pa;
 }
 
 dma_addr_t plat_map_dma_mem(struct device *dev, void *addr, size_t size)
 {
-	return bcm3384_phys_to_dma(dev, virt_to_phys(addr));
+	return bmips_phys_to_dma(dev, virt_to_phys(addr));
 }
 
 dma_addr_t plat_map_dma_mem_page(struct device *dev, struct page *page)
 {
-	return bcm3384_phys_to_dma(dev, page_to_phys(page));
+	return bmips_phys_to_dma(dev, page_to_phys(page));
 }
 
 unsigned long plat_dma_addr_to_phys(struct device *dev, dma_addr_t dma_addr)
 {
-	if (dev && dev_is_pci(dev) &&
-	    dma_addr >= BCM3384_MEM_HOLE_PA)
-		return dma_addr + BCM3384_MEM_HOLE_SIZE;
-	if ((dma_addr ^ bcm3384_dma_xor_mask) <= bcm3384_dma_xor_limit)
-		return dma_addr ^ bcm3384_dma_xor_mask;
+	struct bmips_dma_range *r;
+
+	for (r = bmips_dma_ranges; r && r->size; r++) {
+		if (dma_addr >= r->parent_addr &&
+		    dma_addr < (r->parent_addr + r->size))
+			return dma_addr - r->parent_addr + r->child_addr;
+	}
 	return dma_addr;
 }
 
-static int __init bcm3384_init_dma_xor(void)
+static int __init bmips_init_dma_ranges(void)
 {
-	struct device_node *np = of_find_node_by_type(NULL, "memory");
+	struct device_node *np =
+		of_find_compatible_node(NULL, NULL, "brcm,ubus");
+	const __be32 *data;
+	struct bmips_dma_range *r;
+	int len;
 
 	if (!np)
 		return 0;
 
-	of_property_read_u32(np, "dma-xor-mask", &bcm3384_dma_xor_mask);
-	of_property_read_u32(np, "dma-xor-limit", &bcm3384_dma_xor_limit);
+	data = of_get_property(np, "dma-ranges", &len);
+	if (!data)
+		goto out_good;
+
+	len /= sizeof(*data) * 3;
+	if (!len)
+		goto out_bad;
+
+	/* add a dummy (zero) entry at the end as a sentinel */
+	bmips_dma_ranges = kzalloc(sizeof(struct bmips_dma_range) * (len + 1),
+				   GFP_KERNEL);
+	if (!bmips_dma_ranges)
+		goto out_bad;
 
+	for (r = bmips_dma_ranges; len; len--, r++) {
+		r->child_addr = be32_to_cpup(data++);
+		r->parent_addr = be32_to_cpup(data++);
+		r->size = be32_to_cpup(data++);
+	}
+
+out_good:
 	of_node_put(np);
 	return 0;
+
+out_bad:
+	pr_err("error parsing dma-ranges property\n");
+	of_node_put(np);
+	return -EINVAL;
 }
-arch_initcall(bcm3384_init_dma_xor);
+arch_initcall(bmips_init_dma_ranges);
-- 
2.1.1

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