[PATCHv2] bus: mvebu-mbus: add mv_mbus_dram_info_nooverlap()

Thomas Petazzoni
2015-05-28T09:40:54Z

This commit introduces a variant of the mv_mbus_dram_info() function
called mv_mbus_dram_info_nooverlap(). Both functions are used by
Marvell drivers supporting devices doing DMA, and provide them a
description the DRAM ranges that they need to configure their DRAM
windows.

The ranges provided by the mv_mbus_dram_info() function may overlap
with the I/O windows if there is a lot (>= 4 GB) of RAM
installed. This is not a problem for most of the DMA masters, except
for the upcoming new CESA crypto driver because it does DMA to the
SRAM, which is mapped through an I/O window. For this unit, we need to
have DRAM ranges that do not overlap with the I/O windows.

A first implementation done in commit 1737cac69369 ("bus: mvebu-mbus:
make sure SDRAM CS for DMA don't overlap the MBus bridge window"),
changed the information returned by mv_mbus_dram_info() to match this
requirement. However, it broke the requirement of the other DMA
masters than the DRAM ranges should have power of two sizes.

To solve this situation, this commit introduces a new
mv_mbus_dram_info_nooverlap() function, which returns the same
information as mv_mbus_dram_info(), but guaranteed to not overlap with
the I/O windows.

In the end, it gives us two variants of the mv_mbus_dram_info*()
functions:

- The normal one, mv_mbus_dram_info(), which has been around for many
years. This function returns the raw DRAM ranges, which are
guaranteed to use power of two sizes, but will overlap with I/O
windows. This function will therefore be used by all DMA masters
(SATA, XOR, Ethernet, etc.) except the CESA crypto driver.

- The new 'nooverlap' variant, mv_mbus_dram_info_nooverlap(). This
function returns DRAM ranges after they have been "tweaked" to make
sure they don't overlap with I/O windows. By doing this tweaking,
we remove the power of two size guarantee. This variant will be
used by the new CESA crypto driver.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
---
Changes v1 -> v2:
- Add the missing stub for mv_mbus_dram_info_nooverlap() in mbus.h,
when CONFIG_PLAT_ORION is not defined.
---
drivers/bus/mvebu-mbus.c | 117 +++++++++++++++++++++++++++++++++++++++++++++++
include/linux/mbus.h | 5 ++
2 files changed, 122 insertions(+)

diff --git a/drivers/bus/mvebu-mbus.c b/drivers/bus/mvebu-mbus.c
index 6f047dc..c43c3d2 100644
--- a/drivers/bus/mvebu-mbus.c
+++ b/drivers/bus/mvebu-mbus.c
@@ -57,6 +57,7 @@
#include <linux/of_address.h>
#include <linux/debugfs.h>
#include <linux/log2.h>
+#include <linux/memblock.h>
#include <linux/syscore_ops.h>

/*
@@ -152,13 +153,39 @@ struct mvebu_mbus_state {

static struct mvebu_mbus_state mbus_state;

+/*
+ * We provide two variants of the mv_mbus_dram_info() function:
+ *
+ * - The normal one, where the described DRAM ranges may overlap with
+ * the I/O windows, but for which the DRAM ranges are guaranteed to
+ * have a power of two size. Such ranges are suitable for the DMA
+ * masters that only DMA between the RAM and the device, which is
+ * actually all devices except the crypto engines.
+ *
+ * - The 'nooverlap' one, where the described DRAM ranges are
+ * guaranteed to not overlap with the I/O windows, but for which the
+ * DRAM ranges will not have power of two sizes. They will only be
+ * aligned on a 64 KB boundary, and have a size multiple of 64
+ * KB. Such ranges are suitable for the DMA masters that DMA between
+ * the crypto SRAM (which is mapped through an I/O window) and a
+ * device. This is the case for the crypto engines.
+ */
+
static struct mbus_dram_target_info mvebu_mbus_dram_info;
+static struct mbus_dram_target_info mvebu_mbus_dram_info_nooverlap;
+
const struct mbus_dram_target_info *mv_mbus_dram_info(void)
{
return &mvebu_mbus_dram_info;
}
EXPORT_SYMBOL_GPL(mv_mbus_dram_info);

+const struct mbus_dram_target_info *mv_mbus_dram_info_nooverlap(void)
+{
+ return &mvebu_mbus_dram_info_nooverlap;
+}
+EXPORT_SYMBOL_GPL(mv_mbus_dram_info_nooverlap);
+
/* Checks whether the given window has remap capability */
static bool mvebu_mbus_window_is_remappable(struct mvebu_mbus_state *mbus,
const int win)
@@ -576,6 +603,95 @@ 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 >= 0x100000000ULL)
+ 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 = 0x100000000ULL;
+}
+
+/*
+ * This function fills in the mvebu_mbus_dram_info_nooverlap data
+ * structure, by looking at the mvebu_mbus_dram_info data, and
+ * removing the parts of it that overlap with I/O windows.
+ */
+static void __init
+mvebu_mbus_setup_cpu_target_nooverlap(struct mvebu_mbus_state *mbus)
+{
+ uint64_t mbus_bridge_base, mbus_bridge_end;
+ int cs_nooverlap = 0;
+ int i;
+
+ mvebu_mbus_find_bridge_hole(&mbus_bridge_base, &mbus_bridge_end);
+
+ for (i = 0; i < mvebu_mbus_dram_info.num_cs; i++) {
+ struct mbus_dram_window *w;
+ u64 base, size, end;
+
+ w = &mvebu_mbus_dram_info.cs[i];
+ base = w->base;
+ size = w->size;
+ end = base + size;
+
+ /*
+ * 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;
+ }
+
+ /*
+ * 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_nooverlap.cs[cs_nooverlap++];
+ 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_nooverlap.mbus_dram_target_id = TARGET_DDR;
+ mvebu_mbus_dram_info_nooverlap.num_cs = cs_nooverlap;
+}
+
static void __init
mvebu_mbus_default_setup_cpu_target(struct mvebu_mbus_state *mbus)
{
@@ -964,6 +1080,7 @@ static int __init mvebu_mbus_common_init(struct mvebu_mbus_state *mbus,
mvebu_mbus_disable_window(mbus, win);

mbus->soc->setup_cpu_target(mbus);
+ mvebu_mbus_setup_cpu_target_nooverlap(mbus);

if (is_coherent)
writel(UNIT_SYNC_BARRIER_ALL,
diff --git a/include/linux/mbus.h b/include/linux/mbus.h
index 611b69f..1f7bc63 100644
--- a/include/linux/mbus.h
+++ b/include/linux/mbus.h
@@ -54,11 +54,16 @@ struct mbus_dram_target_info
*/
#ifdef CONFIG_PLAT_ORION
extern const struct mbus_dram_target_info *mv_mbus_dram_info(void);
+extern const struct mbus_dram_target_info *mv_mbus_dram_info_nooverlap(void);
#else
static inline const struct mbus_dram_target_info *mv_mbus_dram_info(void)
{
return NULL;
}
+static inline const struct mbus_dram_target_info *mv_mbus_dram_info_nooverlap(void)
+{
+ return NULL;
+}
#endif

int mvebu_mbus_save_cpu_target(u32 *store_addr);
--
2.1.0