From d791e51e2db7a6ff12c4f0b191b7cdc57faefa0c Mon Sep 17 00:00:00 2001
From: Sascha Hauer <s.hauer@pengutronix.de>
Date: Fri, 20 Dec 2019 12:29:03 +0100
Subject: device: Introduce dma_offset

For devices that do not have a 1:1 mapping between DMA and CPU we need a
dma_offset. This adds dma_offset to struct device_d and starts honoring
it in ARM dma_(un)map_single(). Also we add some comments to functions
that would normally need a device argument to make the DMA <-> CPU
translations device specific.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 arch/arm/cpu/mmu-common.c | 33 +++++++++++++++++++++++++++++++--
 arch/arm/cpu/mmu.c        |  4 ++++
 arch/arm/cpu/mmu_64.c     |  4 ++++
 3 files changed, 39 insertions(+), 2 deletions(-)

(limited to 'arch/arm/cpu')

diff --git a/arch/arm/cpu/mmu-common.c b/arch/arm/cpu/mmu-common.c
index aeefbb2daa..287622b203 100644
--- a/arch/arm/cpu/mmu-common.c
+++ b/arch/arm/cpu/mmu-common.c
@@ -11,9 +11,32 @@
 #include "mmu.h"
 
 
+static inline dma_addr_t cpu_to_dma(struct device_d *dev, unsigned long cpu_addr)
+{
+	dma_addr_t dma_addr = cpu_addr;
+
+	if (dev)
+		dma_addr -= dev->dma_offset;
+
+	return dma_addr;
+}
+
+static inline unsigned long dma_to_cpu(struct device_d *dev, dma_addr_t addr)
+{
+	unsigned long cpu_addr = addr;
+
+	if (dev)
+		cpu_addr += dev->dma_offset;
+
+	return cpu_addr;
+}
+
 void dma_sync_single_for_cpu(dma_addr_t address, size_t size,
 			     enum dma_data_direction dir)
 {
+	/*
+	 * FIXME: This function needs a device argument to support non 1:1 mappings
+	 */
 	if (dir != DMA_TO_DEVICE)
 		dma_inv_range((void *)address, size);
 }
@@ -25,12 +48,14 @@ dma_addr_t dma_map_single(struct device_d *dev, void *ptr, size_t size,
 
 	dma_sync_single_for_device(addr, size, dir);
 
-	return addr;
+	return cpu_to_dma(dev, addr);
 }
 
-void dma_unmap_single(struct device_d *dev, dma_addr_t addr, size_t size,
+void dma_unmap_single(struct device_d *dev, dma_addr_t dma_addr, size_t size,
 		      enum dma_data_direction dir)
 {
+	unsigned long addr = dma_to_cpu(dev, dma_addr);
+
 	dma_sync_single_for_cpu(addr, size, dir);
 }
 
@@ -53,6 +78,10 @@ void *dma_alloc_map(size_t size, dma_addr_t *dma_handle, unsigned flags)
 
 void *dma_alloc_coherent(size_t size, dma_addr_t *dma_handle)
 {
+	/*
+	 * FIXME: This function needs a device argument to support non 1:1 mappings
+	 */
+
 	return dma_alloc_map(size, dma_handle, MAP_UNCACHED);
 }
 
diff --git a/arch/arm/cpu/mmu.c b/arch/arm/cpu/mmu.c
index 158b130b57..1f97c28ec6 100644
--- a/arch/arm/cpu/mmu.c
+++ b/arch/arm/cpu/mmu.c
@@ -491,6 +491,10 @@ void *dma_alloc_writecombine(size_t size, dma_addr_t *dma_handle)
 void dma_sync_single_for_device(dma_addr_t address, size_t size,
 				enum dma_data_direction dir)
 {
+	/*
+	 * FIXME: This function needs a device argument to support non 1:1 mappings
+	 */
+
 	if (dir == DMA_FROM_DEVICE) {
 		__dma_inv_range(address, address + size);
 		if (outer_cache.inv_range)
diff --git a/arch/arm/cpu/mmu_64.c b/arch/arm/cpu/mmu_64.c
index f7a13014af..98cd4c754e 100644
--- a/arch/arm/cpu/mmu_64.c
+++ b/arch/arm/cpu/mmu_64.c
@@ -245,6 +245,10 @@ void dma_flush_range(void *ptr, size_t size)
 void dma_sync_single_for_device(dma_addr_t address, size_t size,
                                 enum dma_data_direction dir)
 {
+	/*
+	 * FIXME: This function needs a device argument to support non 1:1 mappings
+	 */
+
 	if (dir == DMA_FROM_DEVICE)
 		v8_inv_dcache_range(address, address + size - 1);
 	else
-- 
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