[PATCH 2/2] arm: mvebu: Add hardware I/O Coherency support

[gregory.clement@free-electrons.com (Gregory CLEMENT)]

On 10/24/2012 10:11 AM, Yehuda Yitschak wrote:
> 
> 
>> -----Original Message-----
>> From: Gregory CLEMENT [mailto:gregory.clement at free-electrons.com]
>> Sent: Wednesday, October 24, 2012 10:04 AM
>> To: Jason Cooper; Andrew Lunn; Gregory Clement
>> Cc: linux-arm-kernel at lists.infradead.org; Arnd Bergmann; Olof Johansson;
>> Russell King; Rob Herring; Ben Dooks; Ian Molton; Nicolas Pitre; Lior
>> Amsalem; Maen Suleiman; Tawfik Bayouk; Shadi Ammouri; Eran Ben-Avi;
>> Yehuda Yitschak; Nadav Haklai; Ike Pan; Jani Monoses; Chris Van Hoof; Dan
>> Frazier; Thomas Petazzoni; Leif Lindholm; Jon Masters; David Marlin;
>> Sebastian Hesselbarth; linux-kernel at vger.kernel.org
>> Subject: [PATCH 2/2] arm: mvebu: Add hardware I/O Coherency support
>>
>> Armada 370 and XP come with an unit called coherency fabric. This unit
>> allows to use the Armada XP as a nearly coherent architecture. The
>> coherency mechanism uses snoop filters to ensure the coherency between
>> caches, DRAM and devices. This mechanism needs a synchronization barrier
>> which guarantees that all memory write initiated by the devices has
>> reached their target and do not reside in intermediate write buffers. That's
>> why the architecture is not totally coherent and we need to provide our
>> own functions for some DMA operations.
>>
>> Beside the use of the coherency fabric, the device units will have to set the
>> attribute flag to select the accurate coherency process for the memory
>> transaction. This is done each device driver programs the DRAM address
>> windows. The value of the attribute set by the driver is retrieved through
>> the orion_addr_map_cfg struct filled during the early initialization of the
>> platform.
>>
>> Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
>> Reviewed-by: Yehuda Yitschak <yehuday@marvell.com>
>> ---
>>  arch/arm/boot/dts/armada-370-xp.dtsi |    3 +-
>>  arch/arm/mach-mvebu/addr-map.c       |    3 ++
>>  arch/arm/mach-mvebu/armada-370-xp.c  |    1 +
>>  arch/arm/mach-mvebu/coherency.c      |   87
>> ++++++++++++++++++++++++++++++++++
>>  arch/arm/mach-mvebu/common.h         |    2 +
>>  5 files changed, 95 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/boot/dts/armada-370-xp.dtsi
>> b/arch/arm/boot/dts/armada-370-xp.dtsi
>> index 18ba60b..af22e53 100644
>> --- a/arch/arm/boot/dts/armada-370-xp.dtsi
>> +++ b/arch/arm/boot/dts/armada-370-xp.dtsi
>> @@ -38,7 +38,8 @@
>>
>>  	coherency-fabric at d0020200 {
>>  		compatible = "marvell,coherency-fabric";
>> -		reg = <0xd0020200 0xb0>;
>> +		reg = <0xd0020200 0xb0>,
>> +		      <0xd0021010 0x1c>;
>>  	};
>>
>>  	soc {
>> diff --git a/arch/arm/mach-mvebu/addr-map.c b/arch/arm/mach-
>> mvebu/addr-map.c index fe454a4..595f6b7 100644
>> --- a/arch/arm/mach-mvebu/addr-map.c
>> +++ b/arch/arm/mach-mvebu/addr-map.c
>> @@ -108,6 +108,9 @@ static int __init armada_setup_cpu_mbus(void)
>>
>>  	addr_map_cfg.bridge_virt_base = mbus_unit_addr_decoding_base;
>>
>> +	if (of_find_compatible_node(NULL, NULL, "marvell,coherency-
>> fabric"))
>> +		addr_map_cfg.hw_io_coherency = 1;
>> +
>>  	/*
>>  	 * Disable, clear and configure windows.
>>  	 */
>> diff --git a/arch/arm/mach-mvebu/armada-370-xp.c b/arch/arm/mach-
>> mvebu/armada-370-xp.c
>> index 41431a1..3517f7d 100644
>> --- a/arch/arm/mach-mvebu/armada-370-xp.c
>> +++ b/arch/arm/mach-mvebu/armada-370-xp.c
>> @@ -49,6 +49,7 @@ struct sys_timer armada_370_xp_timer = {
>>
>>  static void __init armada_370_xp_dt_init(void)  {
>> +	armada_370_xp_coherency_iocache_init();
>>  	of_platform_populate(NULL, of_default_bus_match_table, NULL,
>> NULL);  }
>>
>> diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-
>> mvebu/coherency.c index 71e27ba..a596ca9 100644
>> --- a/arch/arm/mach-mvebu/coherency.c
>> +++ b/arch/arm/mach-mvebu/coherency.c
>> @@ -22,6 +22,10 @@
>>  #include <linux/of_address.h>
>>  #include <linux/io.h>
>>  #include <linux/smp.h>
>> +#include <linux/dma-mapping.h>
>> +#include <linux/platform_device.h>
>> +#include <asm/smp_plat.h>
>> +
>>  #include "armada-370-xp.h"
>>
>>  /* Some functions in this file are called very early during SMP @@ -31,16
>> +35,53 @@
>>   * value matching its virtual mapping
>>   */
>>  static void __iomem *coherency_base = ARMADA_370_XP_REGS_VIRT_BASE
>> + 0x20200;
>> +static void __iomem *coherency_cpu_base;
>> +
>> +struct dma_map_ops armada_xp_dma_ops;
>>
>>  /* Coherency fabric registers */
>>  #define COHERENCY_FABRIC_CTL_OFFSET		   0x0
>>  #define COHERENCY_FABRIC_CFG_OFFSET		   0x4
>>
>> +#define IO_SYNC_BARRIER_CTL_OFFSET		   0x0
>> +
>>  static struct of_device_id of_coherency_table[] = {
>>  	{.compatible = "marvell,coherency-fabric"},
>>  	{ /* end of list */ },
>>  };
>>
>> +static inline void armada_xp_sync_io_barrier(void) {
>> +	writel(0x1, coherency_cpu_base + IO_SYNC_BARRIER_CTL_OFFSET);
>> +	while (readl(coherency_cpu_base + IO_SYNC_BARRIER_CTL_OFFSET)
>> & 0x1);
>> +}
>> +
>> +dma_addr_t armada_xp_dma_map_page(struct device *dev, struct page
>> *page,
>> +				  unsigned long offset, size_t size,
>> +				  enum dma_data_direction dir,
>> +				  struct dma_attrs *attrs)
>> +{
>> +	if (dir != DMA_TO_DEVICE)
>> +		armada_xp_sync_io_barrier();
>> +	return pfn_to_dma(dev, page_to_pfn(page)) + offset; }
>> +
>> +
>> +void armada_xp_dma_unmap_page(struct device *dev, dma_addr_t
>> dma_handle,
>> +			      size_t size, enum dma_data_direction dir,
>> +			      struct dma_attrs *attrs)
>> +{
>> +	if (dir != DMA_TO_DEVICE)
>> +		armada_xp_sync_io_barrier();
>> +}
>> +
>> +void armada_xp_dma_sync(struct device *dev, dma_addr_t dma_handle,
>> +			size_t size, enum dma_data_direction dir) {
>> +	if (dir != DMA_TO_DEVICE)
>> +		armada_xp_sync_io_barrier();
>> +}
>> +
> 
> Shouldn't all the 4 functions above start with armada_370_xp and not armada_xp ? 
> 

Yes good catch!

> 
>>  int armada_xp_get_cpu_count(void)
> 
> This function can be limited to CONFIG_SP
>

Right


>>  {
>>  	int reg, cnt;
>> @@ -74,6 +115,42 @@ int armada_370_xp_set_cpu_coherent(unsigned int
>> hw_cpu_id, int smp_group_id)
>>  	return 0;
>>  }
>>
>> +static int armada_xp_platform_notifier(struct notifier_block *nb,
>> +				       unsigned long event, void *__dev) {
>> +	struct device *dev = __dev;
>> +
>> +	if (event != BUS_NOTIFY_ADD_DEVICE)
>> +		return NOTIFY_DONE;
>> +	set_dma_ops(dev, &armada_xp_dma_ops);
>> +
>> +	return NOTIFY_OK;
>> +}
>> +
>> +static struct notifier_block armada_xp_platform_nb = {
>> +	.notifier_call = armada_xp_platform_notifier, };
>> +
>> +void __init armada_370_xp_coherency_iocache_init(void)
>> +{
>> +	/* When the coherency fabric is available, the Armada XP and
>> +	 * Aramada 370 are close to a coherent architecture, so we based
>> +	 * our dma ops on the coherent one, and just changes the
>> +	 * operations which need a arch io sync */
>> +	if (of_find_compatible_node(NULL, NULL, "marvell,coherency-
>> fabric")) {
>> +		struct dma_map_ops *dma_ops = &armada_xp_dma_ops;
>> +		memcpy(dma_ops, &arm_coherent_dma_ops,
>> sizeof(*dma_ops));
>> +		dma_ops->map_page = armada_xp_dma_map_page;
>> +		dma_ops->unmap_page = armada_xp_dma_unmap_page;
>> +		dma_ops->unmap_sg = arm_dma_ops.unmap_sg;
>> +		dma_ops->sync_single_for_cpu = armada_xp_dma_sync;
>> +		dma_ops->sync_single_for_device = armada_xp_dma_sync;
>> +		dma_ops->sync_sg_for_cpu =
>> arm_dma_ops.sync_sg_for_cpu;
>> +		dma_ops->sync_sg_for_device =
>> arm_dma_ops.sync_sg_for_device;
>> +	}
>> +	bus_register_notifier(&platform_bus_type,
>> &armada_xp_platform_nb); }
>> +
>>  int __init armada_370_xp_coherency_init(void)
>>  {
>>  	struct device_node *np;
>> @@ -82,7 +159,17 @@ int __init armada_370_xp_coherency_init(void)
>>  	if (np) {
>>  		pr_info("Initializing Coherency fabric\n");
>>  		coherency_base = of_iomap(np, 0);
>> +		coherency_cpu_base = of_iomap(np, 1);
>> +	}
>> +#ifndef CONFIG_SMP
>> +	if (coherency_base) {
>> +		/* In UP case, cpu coherency is enabled here, in SMP case
>> cpu
>> +		 * coherency is enabled for each CPU by
>> +		 * armada_xp_smp_prepare_cpus() in platsmp.c */
>> +		int hw_cpuid = cpu_logical_map(smp_processor_id());
>> +		armada_370_xp_set_cpu_coherent(hw_cpuid, 0);
>>  	}
>> +#endif
>>
>>  	return 0;
>>  }
>> diff --git a/arch/arm/mach-mvebu/common.h b/arch/arm/mach-
>> mvebu/common.h index 86484bb..fff952e 100644
>> --- a/arch/arm/mach-mvebu/common.h
>> +++ b/arch/arm/mach-mvebu/common.h
>> @@ -23,6 +23,8 @@ void armada_370_xp_handle_irq(struct pt_regs *regs);
>>
>>  void armada_xp_cpu_die(unsigned int cpu);
>>
>> +void armada_370_xp_coherency_iocache_init(void);
>> +
>>  int armada_370_xp_coherency_init(void);
>>  int armada_370_xp_pmsu_init(void);
>>  void armada_xp_secondary_startup(void);
>> --
>> 1.7.9.5
> 


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