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Revert "bus: mvebu-mbus: make sure SDRAM CS for DMA don't overlap the MBus bridge window" 

This reverts commit 1737cac693 ("bus: mvebu-mbus: make sure SDRAM CS
for DMA don't overlap the MBus bridge window"), because it breaks DMA
on platforms having more than 2 GB of RAM.

This commit changed the information reported to DMA masters device
drivers through the mv_mbus_dram_info() function so that the returned
DRAM ranges do not overlap with I/O windows.

This was necessary as a preparation to support the new CESA Crypto
Engine driver, which will use DMA for cryptographic operations. But
since it does DMA with the SRAM which is mapped as an I/O window,
having DRAM ranges overlapping with I/O windows was problematic.

To solve this, the above mentioned commit changed the mvebu-mbus to
adjust the DRAM ranges so that they don't overlap with the I/O
windows. However, by doing this, we re-adjust the DRAM ranges in a way
that makes them have a size that is no longer a power of two. While
this is perfectly fine for the Crypto Engine, which supports DRAM
ranges with a granularity of 64 KB, it breaks basically all other DMA
masters, which expect power of two sizes for the DRAM ranges.

Due to this, if the installed system memory is 4 GB, in two
chip-selects of 2 GB, the second DRAM range will be reduced from 2 GB
to a little bit less than 2 GB to not overlap with the I/O windows, in
a way that results in a DRAM range that doesn't have a power of two
size. This means that whenever you do a DMA transfer with an address
located in the [ 2 GB ; 4 GB ] area, it will freeze the system. Any
serious DMA activity like simply running:

  for i in $(seq 1 64) ; do dd if=/dev/urandom of=file$i bs=1M count=16 ; done

in an ext3 partition mounted over a SATA drive will freeze the system.

Since the new CESA crypto driver that uses DMA has not been merged
yet, the easiest fix is to simply revert this commit. A follow-up
commit will introduce a different solution for the CESA crypto driver.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Fixes: 1737cac693 ("bus: mvebu-mbus: make sure SDRAM CS for DMA don't overlap the MBus bridge window")
Cc: <stable@vger.kernel.org> # v4.0+
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
This commit is contained in:
Thomas Petazzoni 2015-05-28 10:40:13 +02:00 committed by Gregory CLEMENT
parent 8c9e06e647
commit 885dbd154b
1 changed files with 16 additions and 89 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

105
drivers/bus/mvebu-mbus.c
View File

@ -58,7 +58,6 @@
#include <linux/debugfs.h>
#include <linux/log2.h>
#include <linux/syscore_ops.h>
#include <linux/memblock.h>
/*
* DDR target is the same on all platforms.
@ -103,9 +102,7 @@
/* Relative to mbusbridge_base */
#define MBUS_BRIDGE_CTRL_OFF 0x0
#define MBUS_BRIDGE_SIZE_MASK 0xffff0000
#define MBUS_BRIDGE_BASE_OFF 0x4
#define MBUS_BRIDGE_BASE_MASK 0xffff0000
/* Maximum number of windows, for all known platforms */
#define MBUS_WINS_MAX 20
@ -579,106 +576,36 @@ static unsigned int armada_xp_mbus_win_remap_offset(int win)
return MVEBU_MBUS_NO_REMAP;
}
/*
* Use the memblock information to find the MBus bridge hole in the
* physical address space.
*/
static void __init
mvebu_mbus_find_bridge_hole(uint64_t *start, uint64_t *end)
{
struct memblock_region *r;
uint64_t s = 0;
for_each_memblock(memory, r) {
/*
* This part of the memory is above 4 GB, so we don't
* care for the MBus bridge hole.
*/
if (r->base >= 0x100000000)
continue;
/*
* The MBus bridge hole is at the end of the RAM under
* the 4 GB limit.
*/
if (r->base + r->size > s)
s = r->base + r->size;
}
*start = s;
*end = 0x100000000;
}
static void __init
mvebu_mbus_default_setup_cpu_target(struct mvebu_mbus_state *mbus)
{
int i;
int cs;
uint64_t mbus_bridge_base, mbus_bridge_end;
mvebu_mbus_dram_info.mbus_dram_target_id = TARGET_DDR;
mvebu_mbus_find_bridge_hole(&mbus_bridge_base, &mbus_bridge_end);
for (i = 0, cs = 0; i < 4; i++) {
u64 base = readl(mbus->sdramwins_base + DDR_BASE_CS_OFF(i));
u64 size = readl(mbus->sdramwins_base + DDR_SIZE_CS_OFF(i));
u64 end;
struct mbus_dram_window *w;
/* Ignore entries that are not enabled */
if (!(size & DDR_SIZE_ENABLED))
continue;
u32 base = readl(mbus->sdramwins_base + DDR_BASE_CS_OFF(i));
u32 size = readl(mbus->sdramwins_base + DDR_SIZE_CS_OFF(i));
/*
* Ignore entries whose base address is above 2^32,
* since devices cannot DMA to such high addresses
* We only take care of entries for which the chip
* select is enabled, and that don't have high base
* address bits set (devices can only access the first
* 32 bits of the memory).
*/
if (base & DDR_BASE_CS_HIGH_MASK)
continue;
if ((size & DDR_SIZE_ENABLED) &&
!(base & DDR_BASE_CS_HIGH_MASK)) {
struct mbus_dram_window *w;
base = base & DDR_BASE_CS_LOW_MASK;
size = (size | ~DDR_SIZE_MASK) + 1;
end = base + size;
/*
* Adjust base/size of the current CS to make sure it
* doesn't overlap with the MBus bridge hole. This is
* particularly important for devices that do DMA from
* DRAM to a SRAM mapped in a MBus window, such as the
* CESA cryptographic engine.
*/
/*
* The CS is fully enclosed inside the MBus bridge
* area, so ignore it.
*/
if (base >= mbus_bridge_base && end <= mbus_bridge_end)
continue;
/*
* Beginning of CS overlaps with end of MBus, raise CS
* base address, and shrink its size.
*/
if (base >= mbus_bridge_base && end > mbus_bridge_end) {
size -= mbus_bridge_end - base;
base = mbus_bridge_end;
w = &mvebu_mbus_dram_info.cs[cs++];
w->cs_index = i;
w->mbus_attr = 0xf & ~(1 << i);
if (mbus->hw_io_coherency)
w->mbus_attr |= ATTR_HW_COHERENCY;
w->base = base & DDR_BASE_CS_LOW_MASK;
w->size = (size | ~DDR_SIZE_MASK) + 1;
}
/*
* End of CS overlaps with beginning of MBus, shrink
* CS size.
*/
if (base < mbus_bridge_base && end > mbus_bridge_base)
size -= end - mbus_bridge_base;
w = &mvebu_mbus_dram_info.cs[cs++];
w->cs_index = i;
w->mbus_attr = 0xf & ~(1 << i);
if (mbus->hw_io_coherency)
w->mbus_attr |= ATTR_HW_COHERENCY;
w->base = base;
w->size = size;
}
mvebu_mbus_dram_info.num_cs = cs;
}