nommu.c
/*
* linux/arch/arm/mm/nommu.c
*
* ARM uCLinux supporting functions.
*/
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/io.h>
#include <linux/memblock.h>
#include <linux/kernel.h>
#include <asm/cacheflush.h>
#include <asm/sections.h>
#include <asm/page.h>
#include <asm/setup.h>
#include <asm/traps.h>
#include <asm/mach/arch.h>
#include <asm/cputype.h>
#include <asm/mpu.h>
#include <asm/procinfo.h>
#include "mm.h"
#ifdef CONFIG_ARM_MPU
struct mpu_rgn_info mpu_rgn_info;
/* Region number */
static void rgnr_write(u32 v)
{
asm("mcr p15, 0, %0, c6, c2, 0" : : "r" (v));
}
/* Data-side / unified region attributes */
/* Region access control register */
static void dracr_write(u32 v)
{
asm("mcr p15, 0, %0, c6, c1, 4" : : "r" (v));
}
/* Region size register */
static void drsr_write(u32 v)
{
asm("mcr p15, 0, %0, c6, c1, 2" : : "r" (v));
}
/* Region base address register */
static void drbar_write(u32 v)
{
asm("mcr p15, 0, %0, c6, c1, 0" : : "r" (v));
}
static u32 drbar_read(void)
{
u32 v;
asm("mrc p15, 0, %0, c6, c1, 0" : "=r" (v));
return v;
}
/* Optional instruction-side region attributes */
/* I-side Region access control register */
static void iracr_write(u32 v)
{
asm("mcr p15, 0, %0, c6, c1, 5" : : "r" (v));
}
/* I-side Region size register */
static void irsr_write(u32 v)
{
asm("mcr p15, 0, %0, c6, c1, 3" : : "r" (v));
}
/* I-side Region base address register */
static void irbar_write(u32 v)
{
asm("mcr p15, 0, %0, c6, c1, 1" : : "r" (v));
}
static unsigned long irbar_read(void)
{
unsigned long v;
asm("mrc p15, 0, %0, c6, c1, 1" : "=r" (v));
return v;
}
/* MPU initialisation functions */
void __init sanity_check_meminfo_mpu(void)
{
phys_addr_t phys_offset = PHYS_OFFSET;
phys_addr_t aligned_region_size, specified_mem_size, rounded_mem_size;
struct memblock_region *reg;
bool first = true;
phys_addr_t mem_start;
phys_addr_t mem_end;
for_each_memblock(memory, reg) {
if (first) {
/*
* Initially only use memory continuous from
* PHYS_OFFSET */
if (reg->base != phys_offset)
panic("First memory bank must be contiguous from PHYS_OFFSET");
mem_start = reg->base;
mem_end = reg->base + reg->size;
specified_mem_size = reg->size;
first = false;
} else {
/*
* memblock auto merges contiguous blocks, remove
* all blocks afterwards in one go (we can't remove
* blocks separately while iterating)
*/
pr_notice("Ignoring RAM after %pa, memory at %pa ignored\n",
&mem_end, ®->base);
memblock_remove(reg->base, 0 - reg->base);
break;
}
}
/*
* MPU has curious alignment requirements: Size must be power of 2, and
* region start must be aligned to the region size
*/
if (phys_offset != 0)
pr_info("PHYS_OFFSET != 0 => MPU Region size constrained by alignment requirements\n");
/*
* Maximum aligned region might overflow phys_addr_t if phys_offset is
* 0. Hence we keep everything below 4G until we take the smaller of
* the aligned_region_size and rounded_mem_size, one of which is
* guaranteed to be smaller than the maximum physical address.
*/
aligned_region_size = (phys_offset - 1) ^ (phys_offset);
/* Find the max power-of-two sized region that fits inside our bank */
rounded_mem_size = (1 << __fls(specified_mem_size)) - 1;
/* The actual region size is the smaller of the two */
aligned_region_size = aligned_region_size < rounded_mem_size
? aligned_region_size + 1
: rounded_mem_size + 1;
if (aligned_region_size != specified_mem_size) {
pr_warn("Truncating memory from %pa to %pa (MPU region constraints)",
&specified_mem_size, &aligned_region_size);
memblock_remove(mem_start + aligned_region_size,
specified_mem_size - aligned_region_size);
mem_end = mem_start + aligned_region_size;
}
pr_debug("MPU Region from %pa size %pa (end %pa))\n",
&phys_offset, &aligned_region_size, &mem_end);
}
static int mpu_present(void)
{
return ((read_cpuid_ext(CPUID_EXT_MMFR0) & MMFR0_PMSA) == MMFR0_PMSAv7);
}
static int mpu_max_regions(void)
{
/*
* We don't support a different number of I/D side regions so if we
* have separate instruction and data memory maps then return
* whichever side has a smaller number of supported regions.
*/
u32 dregions, iregions, mpuir;
mpuir = read_cpuid(CPUID_MPUIR);
dregions = iregions = (mpuir & MPUIR_DREGION_SZMASK) >> MPUIR_DREGION;
/* Check for separate d-side and i-side memory maps */
if (mpuir & MPUIR_nU)
iregions = (mpuir & MPUIR_IREGION_SZMASK) >> MPUIR_IREGION;
/* Use the smallest of the two maxima */
return min(dregions, iregions);
}
static int mpu_iside_independent(void)
{
/* MPUIR.nU specifies whether there is *not* a unified memory map */
return read_cpuid(CPUID_MPUIR) & MPUIR_nU;
}
static int mpu_min_region_order(void)
{
u32 drbar_result, irbar_result;
/* We've kept a region free for this probing */
rgnr_write(MPU_PROBE_REGION);
isb();
/*
* As per ARM ARM, write 0xFFFFFFFC to DRBAR to find the minimum
* region order
*/
drbar_write(0xFFFFFFFC);
drbar_result = irbar_result = drbar_read();
drbar_write(0x0);
/* If the MPU is non-unified, we use the larger of the two minima*/
if (mpu_iside_independent()) {
irbar_write(0xFFFFFFFC);
irbar_result = irbar_read();
irbar_write(0x0);
}
isb(); /* Ensure that MPU region operations have completed */
/* Return whichever result is larger */
return __ffs(max(drbar_result, irbar_result));
}
static int mpu_setup_region(unsigned int number, phys_addr_t start,
unsigned int size_order, unsigned int properties)
{
u32 size_data;
/* We kept a region free for probing resolution of MPU regions*/
if (number > mpu_max_regions() || number == MPU_PROBE_REGION)
return -ENOENT;
if (size_order > 32)
return -ENOMEM;
if (size_order < mpu_min_region_order())
return -ENOMEM;
/* Writing N to bits 5:1 (RSR_SZ) specifies region size 2^N+1 */
size_data = ((size_order - 1) << MPU_RSR_SZ) | 1 << MPU_RSR_EN;
dsb(); /* Ensure all previous data accesses occur with old mappings */
rgnr_write(number);
isb();
drbar_write(start);
dracr_write(properties);
isb(); /* Propagate properties before enabling region */
drsr_write(size_data);
/* Check for independent I-side registers */
if (mpu_iside_independent()) {
irbar_write(start);
iracr_write(properties);
isb();
irsr_write(size_data);
}
isb();
/* Store region info (we treat i/d side the same, so only store d) */
mpu_rgn_info.rgns[number].dracr = properties;
mpu_rgn_info.rgns[number].drbar = start;
mpu_rgn_info.rgns[number].drsr = size_data;
return 0;
}
/*
* Set up default MPU regions, doing nothing if there is no MPU
*/
void __init mpu_setup(void)
{
int region_err;
if (!mpu_present())
return;
region_err = mpu_setup_region(MPU_RAM_REGION, PHYS_OFFSET,
ilog2(memblock.memory.regions[0].size),
MPU_AP_PL1RW_PL0RW | MPU_RGN_NORMAL);
if (region_err) {
panic("MPU region initialization failure! %d", region_err);
} else {
pr_info("Using ARMv7 PMSA Compliant MPU. "
"Region independence: %s, Max regions: %d\n",
mpu_iside_independent() ? "Yes" : "No",
mpu_max_regions());
}
}
#else
static void sanity_check_meminfo_mpu(void) {}
static void __init mpu_setup(void) {}
#endif /* CONFIG_ARM_MPU */
void __init arm_mm_memblock_reserve(void)
{
#ifndef CONFIG_CPU_V7M
/*
* Register the exception vector page.
* some architectures which the DRAM is the exception vector to trap,
* alloc_page breaks with error, although it is not NULL, but "0."
*/
memblock_reserve(CONFIG_VECTORS_BASE, 2 * PAGE_SIZE);
#else /* ifndef CONFIG_CPU_V7M */
/*
* There is no dedicated vector page on V7-M. So nothing needs to be
* reserved here.
*/
#endif
}
void __init sanity_check_meminfo(void)
{
phys_addr_t end;
sanity_check_meminfo_mpu();
end = memblock_end_of_DRAM();
high_memory = __va(end - 1) + 1;
memblock_set_current_limit(end);
}
/*
* paging_init() sets up the page tables, initialises the zone memory
* maps, and sets up the zero page, bad page and bad page tables.
*/
void __init paging_init(const struct machine_desc *mdesc)
{
early_trap_init((void *)CONFIG_VECTORS_BASE);
mpu_setup();
bootmem_init();
}
/*
* We don't need to do anything here for nommu machines.
*/
void setup_mm_for_reboot(void)
{
}
void flush_dcache_page(struct page *page)
{
__cpuc_flush_dcache_area(page_address(page), PAGE_SIZE);
}
EXPORT_SYMBOL(flush_dcache_page);
void flush_kernel_dcache_page(struct page *page)
{
__cpuc_flush_dcache_area(page_address(page), PAGE_SIZE);
}
EXPORT_SYMBOL(flush_kernel_dcache_page);
void copy_to_user_page(struct vm_area_struct *vma, struct page *page,
unsigned long uaddr, void *dst, const void *src,
unsigned long len)
{
memcpy(dst, src, len);
if (vma->vm_flags & VM_EXEC)
__cpuc_coherent_user_range(uaddr, uaddr + len);
}
void __iomem *__arm_ioremap_pfn(unsigned long pfn, unsigned long offset,
size_t size, unsigned int mtype)
{
if (pfn >= (0x100000000ULL >> PAGE_SHIFT))
return NULL;
return (void __iomem *) (offset + (pfn << PAGE_SHIFT));
}
EXPORT_SYMBOL(__arm_ioremap_pfn);
void __iomem *__arm_ioremap_caller(phys_addr_t phys_addr, size_t size,
unsigned int mtype, void *caller)
{
return (void __iomem *)phys_addr;
}
void __iomem * (*arch_ioremap_caller)(phys_addr_t, size_t, unsigned int, void *);
void __iomem *ioremap(resource_size_t res_cookie, size_t size)
{
return __arm_ioremap_caller(res_cookie, size, MT_DEVICE,
__builtin_return_address(0));
}
EXPORT_SYMBOL(ioremap);
void __iomem *ioremap_cache(resource_size_t res_cookie, size_t size)
__alias(ioremap_cached);
void __iomem *ioremap_cached(resource_size_t res_cookie, size_t size)
{
return __arm_ioremap_caller(res_cookie, size, MT_DEVICE_CACHED,
__builtin_return_address(0));
}
EXPORT_SYMBOL(ioremap_cache);
EXPORT_SYMBOL(ioremap_cached);
void __iomem *ioremap_wc(resource_size_t res_cookie, size_t size)
{
return __arm_ioremap_caller(res_cookie, size, MT_DEVICE_WC,
__builtin_return_address(0));
}
EXPORT_SYMBOL(ioremap_wc);
void *arch_memremap_wb(phys_addr_t phys_addr, size_t size)
{
return (void *)phys_addr;
}
void __iounmap(volatile void __iomem *addr)
{
}
EXPORT_SYMBOL(__iounmap);
void (*arch_iounmap)(volatile void __iomem *);
void iounmap(volatile void __iomem *addr)
{
}
EXPORT_SYMBOL(iounmap);