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memory: renesas-rpc-if: Avoid unaligned bus access for HyperFlash

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HyperFlash devices in Renesas SoCs use 2-bytes addressing, according
to HW manual paragraph 62.3.3 (which officially describes Serial Flash
access, but seems to be applicable to HyperFlash too). And 1-byte bus
read operations to 2-bytes unaligned addresses in external address space
read mode work incorrectly (returns the other byte from the same word).

Function memcpy_fromio(), used by the driver to read data from the bus,
in ARM64 architecture (to which Renesas cores belong) uses 8-bytes
bus accesses for appropriate aligned addresses, and 1-bytes accesses
for other addresses. This results in incorrect data read from HyperFlash
in unaligned cases.

This issue can be reproduced using something like the following commands
(where mtd1 is a parition on Hyperflash storage, defined properly
in a device tree):

[Correct fragment, read from Hyperflash]

    root@rcar-gen3:~# dd if=/dev/mtd1 of=/tmp/zz bs=32 count=1
    root@rcar-gen3:~# hexdump -C /tmp/zz
    00000000  f4 03 00 aa f5 03 01 aa  f6 03 02 aa f7 03 03 aa  |................|
    00000010  00 00 80 d2 40 20 18 d5  00 06 81 d2 a0 18 a6 f2  |....@ ..........|
    00000020

[Incorrect read of the same fragment: see the difference at offsets 8-11]

    root@rcar-gen3:~# dd if=/dev/mtd1 of=/tmp/zz bs=12 count=1
    root@rcar-gen3:~# hexdump -C /tmp/zz
    00000000  f4 03 00 aa f5 03 01 aa  03 03 aa aa              |............|
    0000000c

Fix this issue by creating a local replacement of the copying function,
that performs only properly aligned bus accesses, and is used for reading
from HyperFlash.

Fixes: ca7d8b980b ("memory: add Renesas RPC-IF driver")
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Gabbasov <andrew_gabbasov@mentor.com>
Link: https://lore.kernel.org/r/20210922184830.29147-1-andrew_gabbasov@mentor.com
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
This commit is contained in:
Andrew Gabbasov 2021-09-22 13:48:30 -05:00 committed by Krzysztof Kozlowski
parent fff53a551d
commit 1869023e24
1 changed files with 46 additions and 2 deletions
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48
drivers/memory/renesas-rpc-if.c
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@ -185,7 +185,6 @@ static int rpcif_reg_read(void *context, unsigned int reg, unsigned int *val)
*val = readl(rpc->base + reg);
return 0;
}
static int rpcif_reg_write(void *context, unsigned int reg, unsigned int val)
@ -545,6 +544,48 @@ err_out:
}
EXPORT_SYMBOL(rpcif_manual_xfer);
static void memcpy_fromio_readw(void *to,
const void __iomem *from,
size_t count)
{
const int maxw = (IS_ENABLED(CONFIG_64BIT)) ? 8 : 4;
u8 buf[2];
if (count && ((unsigned long)from & 1)) {
*(u16 *)buf = __raw_readw((void __iomem *)((unsigned long)from & ~1));
*(u8 *)to = buf[1];
from++;
to++;
count--;
}
while (count >= 2 && !IS_ALIGNED((unsigned long)from, maxw)) {
*(u16 *)to = __raw_readw(from);
from += 2;
to += 2;
count -= 2;
}
while (count >= maxw) {
#ifdef CONFIG_64BIT
*(u64 *)to = __raw_readq(from);
#else
*(u32 *)to = __raw_readl(from);
#endif
from += maxw;
to += maxw;
count -= maxw;
}
while (count >= 2) {
*(u16 *)to = __raw_readw(from);
from += 2;
to += 2;
count -= 2;
}
if (count) {
*(u16 *)buf = __raw_readw(from);
*(u8 *)to = buf[0];
}
}
ssize_t rpcif_dirmap_read(struct rpcif *rpc, u64 offs, size_t len, void *buf)
{
loff_t from = offs & (RPCIF_DIRMAP_SIZE - 1);
@ -566,7 +607,10 @@ ssize_t rpcif_dirmap_read(struct rpcif *rpc, u64 offs, size_t len, void *buf)
regmap_write(rpc->regmap, RPCIF_DRDMCR, rpc->dummy);
regmap_write(rpc->regmap, RPCIF_DRDRENR, rpc->ddr);
memcpy_fromio(buf, rpc->dirmap + from, len);
if (rpc->bus_size == 2)
memcpy_fromio_readw(buf, rpc->dirmap + from, len);
else
memcpy_fromio(buf, rpc->dirmap + from, len);
pm_runtime_put(rpc->dev);