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

[Gregory CLEMENT]

Hi Thomas,

On 28/05/2015 11:40, Thomas Petazzoni wrote:
> 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 at free-electrons.com>

This patch looks OK for me.

Just to be sure: With the revert done by the previous patch that means that
the crypto driver must be updated to use the new variant, right?

Arnd,

this patch depend on the previous one to apply. However the previous one
is in the branch mvebu/fixes and this one will be in mvebu/drivers. How
I should handle it?

Currently I applied the previous patch on the mvebu/drivers.


Thanks,

Gregory

> ---
> 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);
> 


-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com