[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>

applied on 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