mv_xor: support big endian systems using descriptor swap feature
The mv_xor driver had never been used in a big-endian context, and
therefore was not using the hardware features to support such an
execution environment. The hardware provides a "descriptor swap" bit
that automatically swaps the bytes of the DMA descriptors, within
blocks of 8 bytes. This requires a different DMA descriptor layout on
big-endian systems, as well as enabling this "descriptor swap" bit.
This mechanism is exactly identical to the one already used in the
mv643xx_eth network driver and the mvneta network driver.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Dan Williams <djbw@fb.com>
diff --git a/drivers/dma/mv_xor.c b/drivers/dma/mv_xor.c
index c026b27..d332b9e 100644
--- a/drivers/dma/mv_xor.c
+++ b/drivers/dma/mv_xor.c
@@ -64,7 +64,7 @@
int src_idx)
{
struct mv_xor_desc *hw_desc = desc->hw_desc;
- return hw_desc->phy_src_addr[src_idx];
+ return hw_desc->phy_src_addr[mv_phy_src_idx(src_idx)];
}
@@ -107,7 +107,7 @@
int index, dma_addr_t addr)
{
struct mv_xor_desc *hw_desc = desc->hw_desc;
- hw_desc->phy_src_addr[index] = addr;
+ hw_desc->phy_src_addr[mv_phy_src_idx(index)] = addr;
if (desc->type == DMA_XOR)
hw_desc->desc_command |= (1 << index);
}
@@ -192,6 +192,13 @@
config &= ~0x7;
config |= op_mode;
+
+#if defined(__BIG_ENDIAN)
+ config |= XOR_DESCRIPTOR_SWAP;
+#else
+ config &= ~XOR_DESCRIPTOR_SWAP;
+#endif
+
writel_relaxed(config, XOR_CONFIG(chan));
chan->current_type = type;
}
diff --git a/drivers/dma/mv_xor.h b/drivers/dma/mv_xor.h
index c619359..06b067f 100644
--- a/drivers/dma/mv_xor.h
+++ b/drivers/dma/mv_xor.h
@@ -29,8 +29,10 @@
#define MV_XOR_THRESHOLD 1
#define MV_XOR_MAX_CHANNELS 2
+/* Values for the XOR_CONFIG register */
#define XOR_OPERATION_MODE_XOR 0
#define XOR_OPERATION_MODE_MEMCPY 2
+#define XOR_DESCRIPTOR_SWAP BIT(14)
#define XOR_CURR_DESC(chan) (chan->mmr_base + 0x210 + (chan->idx * 4))
#define XOR_NEXT_DESC(chan) (chan->mmr_base + 0x200 + (chan->idx * 4))
@@ -143,7 +145,16 @@
#endif
};
-/* This structure describes XOR descriptor size 64bytes */
+/*
+ * This structure describes XOR descriptor size 64bytes. The
+ * mv_phy_src_idx() macro must be used when indexing the values of the
+ * phy_src_addr[] array. This is due to the fact that the 'descriptor
+ * swap' feature, used on big endian systems, swaps descriptors data
+ * within blocks of 8 bytes. So two consecutive values of the
+ * phy_src_addr[] array are actually swapped in big-endian, which
+ * explains the different mv_phy_src_idx() implementation.
+ */
+#if defined(__LITTLE_ENDIAN)
struct mv_xor_desc {
u32 status; /* descriptor execution status */
u32 crc32_result; /* result of CRC-32 calculation */
@@ -155,6 +166,21 @@
u32 reserved0;
u32 reserved1;
};
+#define mv_phy_src_idx(src_idx) (src_idx)
+#else
+struct mv_xor_desc {
+ u32 crc32_result; /* result of CRC-32 calculation */
+ u32 status; /* descriptor execution status */
+ u32 phy_next_desc; /* next descriptor address pointer */
+ u32 desc_command; /* type of operation to be carried out */
+ u32 phy_dest_addr; /* destination block address */
+ u32 byte_count; /* size of src/dst blocks in bytes */
+ u32 phy_src_addr[8]; /* source block addresses */
+ u32 reserved1;
+ u32 reserved0;
+};
+#define mv_phy_src_idx(src_idx) (src_idx ^ 1)
+#endif
#define to_mv_sw_desc(addr_hw_desc) \
container_of(addr_hw_desc, struct mv_xor_desc_slot, hw_desc)