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Date: Wed, 25 Feb 2015 16:50:04 +0530
From: Hariprasad Shenai <hariprasad@...lsio.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net, leedom@...lsio.com, anish@...lsio.com,
nirranjan@...lsio.com, kumaras@...lsio.com,
Hariprasad Shenai <hariprasad@...lsio.com>
Subject: [PATCH net] cxgb4: Fix PCI-E Memory window interface for big-endian systems
When doing reads and writes to adapter memory via the PCI-E Memory Window
interface, data gets swizzled on 4-byte boundaries on Big-Endian systems
because we need to account for the register read/write interface which
incorporates a swizzle onto the Little-Endian PCI-E Bus.
Based on original work by Casey Leedom <leedom@...lsio.com>
Signed-off-by: Hariprasad Shenai <hariprasad@...lsio.com>
---
drivers/net/ethernet/chelsio/cxgb4/cxgb4.h | 2 +-
drivers/net/ethernet/chelsio/cxgb4/t4_hw.c | 54 ++++++++++++++++++++++-----
2 files changed, 45 insertions(+), 11 deletions(-)
diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h b/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h
index d6cda17..97842d0 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h
+++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4.h
@@ -1103,7 +1103,7 @@ int t4_restart_aneg(struct adapter *adap, unsigned int mbox, unsigned int port);
#define T4_MEMORY_WRITE 0
#define T4_MEMORY_READ 1
int t4_memory_rw(struct adapter *adap, int win, int mtype, u32 addr, u32 len,
- __be32 *buf, int dir);
+ void *buf, int dir);
static inline int t4_memory_write(struct adapter *adap, int mtype, u32 addr,
u32 len, __be32 *buf)
{
diff --git a/drivers/net/ethernet/chelsio/cxgb4/t4_hw.c b/drivers/net/ethernet/chelsio/cxgb4/t4_hw.c
index 4d643b6..853c389 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/t4_hw.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/t4_hw.c
@@ -449,7 +449,7 @@ int t4_edc_read(struct adapter *adap, int idx, u32 addr, __be32 *data, u64 *ecc)
* @mtype: memory type: MEM_EDC0, MEM_EDC1 or MEM_MC
* @addr: address within indicated memory type
* @len: amount of memory to transfer
- * @buf: host memory buffer
+ * @hbuf: host memory buffer
* @dir: direction of transfer T4_MEMORY_READ (1) or T4_MEMORY_WRITE (0)
*
* Reads/writes an [almost] arbitrary memory region in the firmware: the
@@ -460,15 +460,17 @@ int t4_edc_read(struct adapter *adap, int idx, u32 addr, __be32 *data, u64 *ecc)
* caller's responsibility to perform appropriate byte order conversions.
*/
int t4_memory_rw(struct adapter *adap, int win, int mtype, u32 addr,
- u32 len, __be32 *buf, int dir)
+ u32 len, void *hbuf, int dir)
{
u32 pos, offset, resid, memoffset;
u32 edc_size, mc_size, win_pf, mem_reg, mem_aperture, mem_base;
+ u32 *buf;
/* Argument sanity checks ...
*/
- if (addr & 0x3)
+ if (addr & 0x3 || (uintptr_t)hbuf & 0x3)
return -EINVAL;
+ buf = (u32 *)hbuf;
/* It's convenient to be able to handle lengths which aren't a
* multiple of 32-bits because we often end up transferring files to
@@ -532,14 +534,45 @@ int t4_memory_rw(struct adapter *adap, int win, int mtype, u32 addr,
/* Transfer data to/from the adapter as long as there's an integral
* number of 32-bit transfers to complete.
+ *
+ * A note on Endianness issues:
+ *
+ * The "register" reads and writes below from/to the PCI-E Memory
+ * Window invoke the standard adapter Big-Endian to PCI-E Link
+ * Little-Endian "swizzel." As a result, if we have the following
+ * data in adapter memory:
+ *
+ * Memory: ... | b0 | b1 | b2 | b3 | ...
+ * Address: i+0 i+1 i+2 i+3
+ *
+ * Then a read of the adapter memory via the PCI-E Memory Window
+ * will yield:
+ *
+ * x = readl(i)
+ * 31 0
+ * [ b3 | b2 | b1 | b0 ]
+ *
+ * If this value is stored into local memory on a Little-Endian system
+ * it will show up correctly in local memory as:
+ *
+ * ( ..., b0, b1, b2, b3, ... )
+ *
+ * But on a Big-Endian system, the store will show up in memory
+ * incorrectly swizzled as:
+ *
+ * ( ..., b3, b2, b1, b0, ... )
+ *
+ * So we need to account for this in the reads and writes to the
+ * PCI-E Memory Window below by undoing the register read/write
+ * swizzels.
*/
while (len > 0) {
if (dir == T4_MEMORY_READ)
- *buf++ = (__force __be32) t4_read_reg(adap,
- mem_base + offset);
+ *buf++ = le32_to_cpu((__force __le32)t4_read_reg(adap,
+ mem_base + offset));
else
t4_write_reg(adap, mem_base + offset,
- (__force u32) *buf++);
+ (__force u32)cpu_to_le32(*buf++));
offset += sizeof(__be32);
len -= sizeof(__be32);
@@ -568,15 +601,16 @@ int t4_memory_rw(struct adapter *adap, int win, int mtype, u32 addr,
*/
if (resid) {
union {
- __be32 word;
+ u32 word;
char byte[4];
} last;
unsigned char *bp;
int i;
if (dir == T4_MEMORY_READ) {
- last.word = (__force __be32) t4_read_reg(adap,
- mem_base + offset);
+ last.word = le32_to_cpu(
+ (__force __le32)t4_read_reg(adap,
+ mem_base + offset));
for (bp = (unsigned char *)buf, i = resid; i < 4; i++)
bp[i] = last.byte[i];
} else {
@@ -584,7 +618,7 @@ int t4_memory_rw(struct adapter *adap, int win, int mtype, u32 addr,
for (i = resid; i < 4; i++)
last.byte[i] = 0;
t4_write_reg(adap, mem_base + offset,
- (__force u32) last.word);
+ (__force u32)cpu_to_le32(last.word));
}
}
--
1.7.1
--
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