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	ARC: mm: Decouple RAM base address from kernel link address
[Needed for HSDK]
Currently the first page of system (hence RAM base) is assumed to be
@ CONFIG_LINUX_LINK_BASE, where kernel itself is linked.
However is case of HSDK platform, for reasons explained in that patch,
this is not true. kernel needs to be linked @ 0x9000_0000 while DDR
is still wired at 0x8000_0000. To properly account for this 256M of RAM,
we need to introduce a new option and base page frame accountiing off of
it.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
[vgupta: renamed  CONFIG_KERNEL_RAM_BASE_ADDRESS => CONFIG_LINUX_RAM_BASE
       : simplified changelog]
			
			
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					 8 changed files with 18 additions and 10 deletions
				
			
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			@ -418,7 +418,7 @@ endif	# ISA_ARCV2
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endmenu   # "ARC CPU Configuration"
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config LINUX_LINK_BASE
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	hex "Linux Link Address"
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	hex "Kernel link address"
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	default "0x80000000"
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	help
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	  ARC700 divides the 32 bit phy address space into two equal halves
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			@ -431,6 +431,14 @@ config LINUX_LINK_BASE
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	  If you don't know what the above means, leave this setting alone.
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	  This needs to match memory start address specified in Device Tree
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config LINUX_RAM_BASE
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	hex "RAM base address"
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	default LINUX_LINK_BASE
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	help
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	  By default Linux is linked at base of RAM. However in some special
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	  cases (such as HSDK), Linux can't be linked at start of DDR, hence
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	  this option.
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config HIGHMEM
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	bool "High Memory Support"
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	select ARCH_DISCONTIGMEM_ENABLE
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			@ -99,7 +99,7 @@ mb_intc: dw-apb-ictl@0xe0012000 {
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	memory {
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		device_type = "memory";
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		/* CONFIG_KERNEL_RAM_BASE_ADDRESS needs to match low mem start */
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		/* CONFIG_LINUX_RAM_BASE needs to match low mem start */
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		reg = <0x0 0x80000000 0x0 0x1b000000>;	/* (512 - 32) MiB */
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	};
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			@ -109,7 +109,7 @@ mb_intc: dw-apb-ictl@0xe0012000 {
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	memory {
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		device_type = "memory";
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		/* CONFIG_KERNEL_RAM_BASE_ADDRESS needs to match low mem start */
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		/* CONFIG_LINUX_RAM_BASE needs to match low mem start */
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		reg = <0x0 0x80000000 0x0 0x20000000	/* 512 MiB low mem */
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		       0x1 0xc0000000 0x0 0x40000000>;	/* 1 GiB highmem */
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	};
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			@ -115,7 +115,7 @@ mb_intc: dw-apb-ictl@0xe0012000 {
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	memory {
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		device_type = "memory";
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		/* CONFIG_KERNEL_RAM_BASE_ADDRESS needs to match low mem start */
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		/* CONFIG_LINUX_RAM_BASE needs to match low mem start */
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		reg = <0x0 0x80000000 0x0 0x20000000	/* 512 MiB low mem */
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		       0x1 0xc0000000 0x0 0x40000000>;	/* 1 GiB highmem */
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	};
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			@ -18,7 +18,7 @@ / {
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	memory {
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		device_type = "memory";
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		/* CONFIG_LINUX_LINK_BASE needs to match low mem start */
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		/* CONFIG_LINUX_RAM_BASE needs to match low mem start */
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		reg = <0x0 0x80000000 0x0 0x20000000	/* 512 MB low mem */
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		       0x1 0x00000000 0x0 0x40000000>;	/* 1 GB highmem */
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	};
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			@ -85,7 +85,7 @@ typedef pte_t * pgtable_t;
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 */
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#define virt_to_pfn(kaddr)	(__pa(kaddr) >> PAGE_SHIFT)
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#define ARCH_PFN_OFFSET		virt_to_pfn(CONFIG_LINUX_LINK_BASE)
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#define ARCH_PFN_OFFSET		virt_to_pfn(CONFIG_LINUX_RAM_BASE)
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#ifdef CONFIG_FLATMEM
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#define pfn_valid(pfn)		(((pfn) - ARCH_PFN_OFFSET) < max_mapnr)
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			@ -1173,7 +1173,7 @@ noinline void __init arc_ioc_setup(void)
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	write_aux_reg(ARC_REG_IO_COH_AP0_SIZE, order_base_2(mem_sz >> 10) - 2);
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	/* for now assume kernel base is start of IOC aperture */
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	ioc_base = CONFIG_LINUX_LINK_BASE;
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	ioc_base = CONFIG_LINUX_RAM_BASE;
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	if (ioc_base % mem_sz != 0)
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		panic("IOC Aperture start must be aligned to the size of the aperture");
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			@ -26,7 +26,7 @@ pgd_t swapper_pg_dir[PTRS_PER_PGD] __aligned(PAGE_SIZE);
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char empty_zero_page[PAGE_SIZE] __aligned(PAGE_SIZE);
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EXPORT_SYMBOL(empty_zero_page);
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static const unsigned long low_mem_start = CONFIG_LINUX_LINK_BASE;
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static const unsigned long low_mem_start = CONFIG_LINUX_RAM_BASE;
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static unsigned long low_mem_sz;
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#ifdef CONFIG_HIGHMEM
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			@ -63,7 +63,7 @@ void __init early_init_dt_add_memory_arch(u64 base, u64 size)
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	if (!low_mem_sz) {
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		if (base != low_mem_start)
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			panic("CONFIG_LINUX_LINK_BASE != DT memory { }");
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			panic("CONFIG_LINUX_RAM_BASE != DT memory { }");
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		low_mem_sz = size;
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		in_use = 1;
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			@ -161,7 +161,7 @@ void __init setup_arch_memory(void)
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	 * We can't use the helper free_area_init(zones[]) because it uses
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	 * PAGE_OFFSET to compute the @min_low_pfn which would be wrong
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	 * when our kernel doesn't start at PAGE_OFFSET, i.e.
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	 * PAGE_OFFSET != CONFIG_LINUX_LINK_BASE
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	 * PAGE_OFFSET != CONFIG_LINUX_RAM_BASE
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	 */
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	free_area_init_node(0,			/* node-id */
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			    zones_size,		/* num pages per zone */
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