arch/arm/mm/pmsa-v7.c - linux - Git at Google

 /*
  * Based on linux/arch/arm/mm/nommu.c
  *
  * ARM PMSAv7 supporting functions.
  */

 #include <linux/bitops.h>
 #include <linux/memblock.h>
 #include <linux/string.h>

 #include <asm/cacheflush.h>
 #include <asm/cp15.h>
 #include <asm/cputype.h>
 #include <asm/mpu.h>
 #include <asm/sections.h>

 #include "mm.h"

 struct region {
 	phys_addr_t base;
 	phys_addr_t size;
 	unsigned long subreg;
 };

 static struct region __initdata mem[MPU_MAX_REGIONS];
 #ifdef CONFIG_XIP_KERNEL
 static struct region __initdata xip[MPU_MAX_REGIONS];
 #endif

 static unsigned int __initdata mpu_min_region_order;
 static unsigned int __initdata mpu_max_regions;

 static int __init __mpu_min_region_order(void);
 static int __init __mpu_max_regions(void);

 #ifndef CONFIG_CPU_V7M

 #define DRBAR	__ACCESS_CP15(c6, 0, c1, 0)
 #define IRBAR	__ACCESS_CP15(c6, 0, c1, 1)
 #define DRSR	__ACCESS_CP15(c6, 0, c1, 2)
 #define IRSR	__ACCESS_CP15(c6, 0, c1, 3)
 #define DRACR	__ACCESS_CP15(c6, 0, c1, 4)
 #define IRACR	__ACCESS_CP15(c6, 0, c1, 5)
 #define RNGNR	__ACCESS_CP15(c6, 0, c2, 0)

 /* Region number */
 static inline void rgnr_write(u32 v)
 {
 	write_sysreg(v, RNGNR);
 }

 /* Data-side / unified region attributes */

 /* Region access control register */
 static inline void dracr_write(u32 v)
 {
 	write_sysreg(v, DRACR);
 }

 /* Region size register */
 static inline void drsr_write(u32 v)
 {
 	write_sysreg(v, DRSR);
 }

 /* Region base address register */
 static inline void drbar_write(u32 v)
 {
 	write_sysreg(v, DRBAR);
 }

 static inline u32 drbar_read(void)
 {
 	return read_sysreg(DRBAR);
 }
 /* Optional instruction-side region attributes */

 /* I-side Region access control register */
 static inline void iracr_write(u32 v)
 {
 	write_sysreg(v, IRACR);
 }

 /* I-side Region size register */
 static inline void irsr_write(u32 v)
 {
 	write_sysreg(v, IRSR);
 }

 /* I-side Region base address register */
 static inline void irbar_write(u32 v)
 {
 	write_sysreg(v, IRBAR);
 }

 static inline u32 irbar_read(void)
 {
 	return read_sysreg(IRBAR);
 }

 #else

 static inline void rgnr_write(u32 v)
 {
 	writel_relaxed(v, BASEADDR_V7M_SCB + PMSAv7_RNR);
 }

 /* Data-side / unified region attributes */

 /* Region access control register */
 static inline void dracr_write(u32 v)
 {
 	u32 rsr = readl_relaxed(BASEADDR_V7M_SCB + PMSAv7_RASR) & GENMASK(15, 0);

 	writel_relaxed((v << 16) | rsr, BASEADDR_V7M_SCB + PMSAv7_RASR);
 }

 /* Region size register */
 static inline void drsr_write(u32 v)
 {
 	u32 racr = readl_relaxed(BASEADDR_V7M_SCB + PMSAv7_RASR) & GENMASK(31, 16);

 	writel_relaxed(v | racr, BASEADDR_V7M_SCB + PMSAv7_RASR);
 }

 /* Region base address register */
 static inline void drbar_write(u32 v)
 {
 	writel_relaxed(v, BASEADDR_V7M_SCB + PMSAv7_RBAR);
 }

 static inline u32 drbar_read(void)
 {
 	return readl_relaxed(BASEADDR_V7M_SCB + PMSAv7_RBAR);
 }

 /* ARMv7-M only supports a unified MPU, so I-side operations are nop */

 static inline void iracr_write(u32 v) {}
 static inline void irsr_write(u32 v) {}
 static inline void irbar_write(u32 v) {}
 static inline unsigned long irbar_read(void) {return 0;}

 #endif

 static bool __init try_split_region(phys_addr_t base, phys_addr_t size, struct region *region)
 {
 	unsigned long  subreg, bslots, sslots;
 	phys_addr_t abase = base & ~(size - 1);
 	phys_addr_t asize = base + size - abase;
 	phys_addr_t p2size = 1 << __fls(asize);
 	phys_addr_t bdiff, sdiff;

 	if (p2size != asize)
 		p2size *= 2;

 	bdiff = base - abase;
 	sdiff = p2size - asize;
 	subreg = p2size / PMSAv7_NR_SUBREGS;

 	if ((bdiff % subreg) || (sdiff % subreg))
 		return false;

 	bslots = bdiff / subreg;
 	sslots = sdiff / subreg;

 	if (bslots || sslots) {
 		int i;

 		if (subreg < PMSAv7_MIN_SUBREG_SIZE)
 			return false;

 		if (bslots + sslots > PMSAv7_NR_SUBREGS)
 			return false;

 		for (i = 0; i < bslots; i++)
 			_set_bit(i, &region->subreg);

 		for (i = 1; i <= sslots; i++)
 			_set_bit(PMSAv7_NR_SUBREGS - i, &region->subreg);
 	}

 	region->base = abase;
 	region->size = p2size;

 	return true;
 }

 static int __init allocate_region(phys_addr_t base, phys_addr_t size,
 				  unsigned int limit, struct region *regions)
 {
 	int count = 0;
 	phys_addr_t diff = size;
 	int attempts = MPU_MAX_REGIONS;

 	while (diff) {
 		/* Try cover region as is (maybe with help of subregions) */
 		if (try_split_region(base, size, &regions[count])) {
 			count++;
 			base += size;
 			diff -= size;
 			size = diff;
 		} else {
 			/*
 			 * Maximum aligned region might overflow phys_addr_t
 			 * if "base" is 0. Hence we keep everything below 4G
 			 * until we take the smaller of the aligned region
 			 * size ("asize") and rounded region size ("p2size"),
 			 * one of which is guaranteed to be smaller than the
 			 * maximum physical address.
 			 */
 			phys_addr_t asize = (base - 1) ^ base;
 			phys_addr_t p2size = (1 <<  __fls(diff)) - 1;

 			size = asize < p2size ? asize + 1 : p2size + 1;
 		}

 		if (count > limit)
 			break;

 		if (!attempts)
 			break;

 		attempts--;
 	}

 	return count;
 }

 /* MPU initialisation functions */
 void __init pmsav7_adjust_lowmem_bounds(void)
 {
 	phys_addr_t  specified_mem_size = 0, total_mem_size = 0;
 	phys_addr_t mem_start;
 	phys_addr_t mem_end;
 	phys_addr_t reg_start, reg_end;
 	unsigned int mem_max_regions;
 	bool first = true;
 	int num;
 	u64 i;

 	/* Free-up PMSAv7_PROBE_REGION */
 	mpu_min_region_order = __mpu_min_region_order();

 	/* How many regions are supported */
 	mpu_max_regions = __mpu_max_regions();

 	mem_max_regions = min((unsigned int)MPU_MAX_REGIONS, mpu_max_regions);

 	/* We need to keep one slot for background region */
 	mem_max_regions--;

 #ifndef CONFIG_CPU_V7M
 	/* ... and one for vectors */
 	mem_max_regions--;
 #endif

 #ifdef CONFIG_XIP_KERNEL
 	/* plus some regions to cover XIP ROM */
 	num = allocate_region(CONFIG_XIP_PHYS_ADDR, __pa(_exiprom) - CONFIG_XIP_PHYS_ADDR,
 			      mem_max_regions, xip);

 	mem_max_regions -= num;
 #endif

 	for_each_mem_range(i, &reg_start, &reg_end) {
 		if (first) {
 			phys_addr_t phys_offset = PHYS_OFFSET;

 			/*
 			 * Initially only use memory continuous from
 			 * PHYS_OFFSET */
 			if (reg_start != phys_offset)
 				panic("First memory bank must be contiguous from PHYS_OFFSET");

 			mem_start = reg_start;
 			mem_end = reg_end;
 			specified_mem_size = mem_end - mem_start;
 			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, &reg_start);
 			memblock_remove(reg_start, 0 - reg_start);
 			break;
 		}
 	}

 	memset(mem, 0, sizeof(mem));
 	num = allocate_region(mem_start, specified_mem_size, mem_max_regions, mem);

 	for (i = 0; i < num; i++) {
 		unsigned long  subreg = mem[i].size / PMSAv7_NR_SUBREGS;

 		total_mem_size += mem[i].size - subreg * hweight_long(mem[i].subreg);

 		pr_debug("MPU: base %pa size %pa disable subregions: %*pbl\n",
 			 &mem[i].base, &mem[i].size, PMSAv7_NR_SUBREGS, &mem[i].subreg);
 	}

 	if (total_mem_size != specified_mem_size) {
 		pr_warn("Truncating memory from %pa to %pa (MPU region constraints)",
 				&specified_mem_size, &total_mem_size);
 		memblock_remove(mem_start + total_mem_size,
 				specified_mem_size - total_mem_size);
 	}
 }

 static int __init __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_mputype();

 	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 __init mpu_iside_independent(void)
 {
 	/* MPUIR.nU specifies whether there is *not* a unified memory map */
 	return read_cpuid_mputype() & MPUIR_nU;
 }

 static int __init __mpu_min_region_order(void)
 {
 	u32 drbar_result, irbar_result;

 	/* We've kept a region free for this probing */
 	rgnr_write(PMSAv7_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 __init mpu_setup_region(unsigned int number, phys_addr_t start,
 				   unsigned int size_order, unsigned int properties,
 				   unsigned int subregions, bool need_flush)
 {
 	u32 size_data;

 	/* We kept a region free for probing resolution of MPU regions*/
 	if (number > mpu_max_regions
 	    || number >= MPU_MAX_REGIONS)
 		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) << PMSAv7_RSR_SZ) | 1 << PMSAv7_RSR_EN;
 	size_data |= subregions << PMSAv7_RSR_SD;

 	if (need_flush)
 		flush_cache_all();

 	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;

 	mpu_rgn_info.used++;

 	return 0;
 }

 /*
 * Set up default MPU regions, doing nothing if there is no MPU
 */
 void __init pmsav7_setup(void)
 {
 	int i, region = 0, err = 0;

 	/* Setup MPU (order is important) */

 	/* Background */
 	err |= mpu_setup_region(region++, 0, 32,
 				PMSAv7_ACR_XN | PMSAv7_RGN_STRONGLY_ORDERED | PMSAv7_AP_PL1RW_PL0RW,
 				0, false);

 #ifdef CONFIG_XIP_KERNEL
 	/* ROM */
 	for (i = 0; i < ARRAY_SIZE(xip); i++) {
 		/*
                  * In case we overwrite RAM region we set earlier in
                  * head-nommu.S (which is cachable) all subsequent
                  * data access till we setup RAM bellow would be done
                  * with BG region (which is uncachable), thus we need
                  * to clean and invalidate cache.
 		 */
 		bool need_flush = region == PMSAv7_RAM_REGION;

 		if (!xip[i].size)
 			continue;

 		err |= mpu_setup_region(region++, xip[i].base, ilog2(xip[i].size),
 					PMSAv7_AP_PL1RO_PL0NA | PMSAv7_RGN_NORMAL,
 					xip[i].subreg, need_flush);
 	}
 #endif

 	/* RAM */
 	for (i = 0; i < ARRAY_SIZE(mem); i++) {
 		if (!mem[i].size)
 			continue;

 		err |= mpu_setup_region(region++, mem[i].base, ilog2(mem[i].size),
 					PMSAv7_AP_PL1RW_PL0RW | PMSAv7_RGN_NORMAL,
 					mem[i].subreg, false);
 	}

 	/* Vectors */
 #ifndef CONFIG_CPU_V7M
 	err |= mpu_setup_region(region++, vectors_base, ilog2(2 * PAGE_SIZE),
 				PMSAv7_AP_PL1RW_PL0NA | PMSAv7_RGN_NORMAL,
 				0, false);
 #endif
 	if (err) {
 		panic("MPU region initialization failure! %d", err);
 	} else {
 		pr_info("Using ARMv7 PMSA Compliant MPU. "
 			 "Region independence: %s, Used %d of %d regions\n",
 			mpu_iside_independent() ? "Yes" : "No",
 			mpu_rgn_info.used, mpu_max_regions);
 	}
 }
	/*
	* Based on linux/arch/arm/mm/nommu.c
	*
	* ARM PMSAv7 supporting functions.
	*/

	#include <linux/bitops.h>
	#include <linux/memblock.h>
	#include <linux/string.h>

	#include <asm/cacheflush.h>
	#include <asm/cp15.h>
	#include <asm/cputype.h>
	#include <asm/mpu.h>
	#include <asm/sections.h>

	#include "mm.h"

	struct region {
	phys_addr_t base;
	phys_addr_t size;
	unsigned long subreg;
	};

	static struct region __initdata mem[MPU_MAX_REGIONS];
	#ifdef CONFIG_XIP_KERNEL
	static struct region __initdata xip[MPU_MAX_REGIONS];
	#endif

	static unsigned int __initdata mpu_min_region_order;
	static unsigned int __initdata mpu_max_regions;

	static int __init __mpu_min_region_order(void);
	static int __init __mpu_max_regions(void);

	#ifndef CONFIG_CPU_V7M

	#define DRBAR __ACCESS_CP15(c6, 0, c1, 0)
	#define IRBAR __ACCESS_CP15(c6, 0, c1, 1)
	#define DRSR __ACCESS_CP15(c6, 0, c1, 2)
	#define IRSR __ACCESS_CP15(c6, 0, c1, 3)
	#define DRACR __ACCESS_CP15(c6, 0, c1, 4)
	#define IRACR __ACCESS_CP15(c6, 0, c1, 5)
	#define RNGNR __ACCESS_CP15(c6, 0, c2, 0)

	/* Region number */
	static inline void rgnr_write(u32 v)
	{
	write_sysreg(v, RNGNR);
	}

	/* Data-side / unified region attributes */

	/* Region access control register */
	static inline void dracr_write(u32 v)
	{
	write_sysreg(v, DRACR);
	}

	/* Region size register */
	static inline void drsr_write(u32 v)
	{
	write_sysreg(v, DRSR);
	}

	/* Region base address register */
	static inline void drbar_write(u32 v)
	{
	write_sysreg(v, DRBAR);
	}

	static inline u32 drbar_read(void)
	{
	return read_sysreg(DRBAR);
	}
	/* Optional instruction-side region attributes */

	/* I-side Region access control register */
	static inline void iracr_write(u32 v)
	{
	write_sysreg(v, IRACR);
	}

	/* I-side Region size register */
	static inline void irsr_write(u32 v)
	{
	write_sysreg(v, IRSR);
	}

	/* I-side Region base address register */
	static inline void irbar_write(u32 v)
	{
	write_sysreg(v, IRBAR);
	}

	static inline u32 irbar_read(void)
	{
	return read_sysreg(IRBAR);
	}

	#else

	static inline void rgnr_write(u32 v)
	{
	writel_relaxed(v, BASEADDR_V7M_SCB + PMSAv7_RNR);
	}

	/* Data-side / unified region attributes */

	/* Region access control register */
	static inline void dracr_write(u32 v)
	{
	u32 rsr = readl_relaxed(BASEADDR_V7M_SCB + PMSAv7_RASR) & GENMASK(15, 0);

	writel_relaxed((v << 16) \| rsr, BASEADDR_V7M_SCB + PMSAv7_RASR);
	}

	/* Region size register */
	static inline void drsr_write(u32 v)
	{
	u32 racr = readl_relaxed(BASEADDR_V7M_SCB + PMSAv7_RASR) & GENMASK(31, 16);

	writel_relaxed(v \| racr, BASEADDR_V7M_SCB + PMSAv7_RASR);
	}

	/* Region base address register */
	static inline void drbar_write(u32 v)
	{
	writel_relaxed(v, BASEADDR_V7M_SCB + PMSAv7_RBAR);
	}

	static inline u32 drbar_read(void)
	{
	return readl_relaxed(BASEADDR_V7M_SCB + PMSAv7_RBAR);
	}

	/* ARMv7-M only supports a unified MPU, so I-side operations are nop */

	static inline void iracr_write(u32 v) {}
	static inline void irsr_write(u32 v) {}
	static inline void irbar_write(u32 v) {}
	static inline unsigned long irbar_read(void) {return 0;}

	#endif

	static bool __init try_split_region(phys_addr_t base, phys_addr_t size, struct region *region)
	{
	unsigned long subreg, bslots, sslots;
	phys_addr_t abase = base & ~(size - 1);
	phys_addr_t asize = base + size - abase;
	phys_addr_t p2size = 1 << __fls(asize);
	phys_addr_t bdiff, sdiff;

	if (p2size != asize)
	p2size *= 2;

	bdiff = base - abase;
	sdiff = p2size - asize;
	subreg = p2size / PMSAv7_NR_SUBREGS;

	if ((bdiff % subreg) \|\| (sdiff % subreg))
	return false;

	bslots = bdiff / subreg;
	sslots = sdiff / subreg;

	if (bslots \|\| sslots) {
	int i;

	if (subreg < PMSAv7_MIN_SUBREG_SIZE)
	return false;

	if (bslots + sslots > PMSAv7_NR_SUBREGS)
	return false;

	for (i = 0; i < bslots; i++)
	_set_bit(i, &region->subreg);

	for (i = 1; i <= sslots; i++)
	_set_bit(PMSAv7_NR_SUBREGS - i, &region->subreg);
	}

	region->base = abase;
	region->size = p2size;

	return true;
	}

	static int __init allocate_region(phys_addr_t base, phys_addr_t size,
	unsigned int limit, struct region *regions)
	{
	int count = 0;
	phys_addr_t diff = size;
	int attempts = MPU_MAX_REGIONS;

	while (diff) {
	/* Try cover region as is (maybe with help of subregions) */
	if (try_split_region(base, size, &regions[count])) {
	count++;
	base += size;
	diff -= size;
	size = diff;
	} else {
	/*
	* Maximum aligned region might overflow phys_addr_t
	* if "base" is 0. Hence we keep everything below 4G
	* until we take the smaller of the aligned region
	* size ("asize") and rounded region size ("p2size"),
	* one of which is guaranteed to be smaller than the
	* maximum physical address.
	*/
	phys_addr_t asize = (base - 1) ^ base;
	phys_addr_t p2size = (1 << __fls(diff)) - 1;

	size = asize < p2size ? asize + 1 : p2size + 1;
	}

	if (count > limit)
	break;

	if (!attempts)
	break;

	attempts--;
	}

	return count;
	}

	/* MPU initialisation functions */
	void __init pmsav7_adjust_lowmem_bounds(void)
	{
	phys_addr_t specified_mem_size = 0, total_mem_size = 0;
	phys_addr_t mem_start;
	phys_addr_t mem_end;
	phys_addr_t reg_start, reg_end;
	unsigned int mem_max_regions;
	bool first = true;
	int num;
	u64 i;

	/* Free-up PMSAv7_PROBE_REGION */
	mpu_min_region_order = __mpu_min_region_order();

	/* How many regions are supported */
	mpu_max_regions = __mpu_max_regions();

	mem_max_regions = min((unsigned int)MPU_MAX_REGIONS, mpu_max_regions);

	/* We need to keep one slot for background region */
	mem_max_regions--;

	#ifndef CONFIG_CPU_V7M
	/* ... and one for vectors */
	mem_max_regions--;
	#endif

	#ifdef CONFIG_XIP_KERNEL
	/* plus some regions to cover XIP ROM */
	num = allocate_region(CONFIG_XIP_PHYS_ADDR, __pa(_exiprom) - CONFIG_XIP_PHYS_ADDR,
	mem_max_regions, xip);

	mem_max_regions -= num;
	#endif

	for_each_mem_range(i, &reg_start, &reg_end) {
	if (first) {
	phys_addr_t phys_offset = PHYS_OFFSET;

	/*
	* Initially only use memory continuous from
	* PHYS_OFFSET */
	if (reg_start != phys_offset)
	panic("First memory bank must be contiguous from PHYS_OFFSET");

	mem_start = reg_start;
	mem_end = reg_end;
	specified_mem_size = mem_end - mem_start;
	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, &reg_start);
	memblock_remove(reg_start, 0 - reg_start);
	break;
	}
	}

	memset(mem, 0, sizeof(mem));
	num = allocate_region(mem_start, specified_mem_size, mem_max_regions, mem);

	for (i = 0; i < num; i++) {
	unsigned long subreg = mem[i].size / PMSAv7_NR_SUBREGS;

	total_mem_size += mem[i].size - subreg * hweight_long(mem[i].subreg);

	pr_debug("MPU: base %pa size %pa disable subregions: %*pbl\n",
	&mem[i].base, &mem[i].size, PMSAv7_NR_SUBREGS, &mem[i].subreg);
	}

	if (total_mem_size != specified_mem_size) {
	pr_warn("Truncating memory from %pa to %pa (MPU region constraints)",
	&specified_mem_size, &total_mem_size);
	memblock_remove(mem_start + total_mem_size,
	specified_mem_size - total_mem_size);
	}
	}

	static int __init __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_mputype();

	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 __init mpu_iside_independent(void)
	{
	/* MPUIR.nU specifies whether there is not a unified memory map */
	return read_cpuid_mputype() & MPUIR_nU;
	}

	static int __init __mpu_min_region_order(void)
	{
	u32 drbar_result, irbar_result;

	/* We've kept a region free for this probing */
	rgnr_write(PMSAv7_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 __init mpu_setup_region(unsigned int number, phys_addr_t start,
	unsigned int size_order, unsigned int properties,
	unsigned int subregions, bool need_flush)
	{
	u32 size_data;

	/* We kept a region free for probing resolution of MPU regions*/
	if (number > mpu_max_regions
	\|\| number >= MPU_MAX_REGIONS)
	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) << PMSAv7_RSR_SZ) \| 1 << PMSAv7_RSR_EN;
	size_data \|= subregions << PMSAv7_RSR_SD;

	if (need_flush)
	flush_cache_all();

	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;

	mpu_rgn_info.used++;

	return 0;
	}

	/*
	* Set up default MPU regions, doing nothing if there is no MPU
	*/
	void __init pmsav7_setup(void)
	{
	int i, region = 0, err = 0;

	/* Setup MPU (order is important) */

	/* Background */
	err \|= mpu_setup_region(region++, 0, 32,
	PMSAv7_ACR_XN \| PMSAv7_RGN_STRONGLY_ORDERED \| PMSAv7_AP_PL1RW_PL0RW,
	0, false);

	#ifdef CONFIG_XIP_KERNEL
	/* ROM */
	for (i = 0; i < ARRAY_SIZE(xip); i++) {
	/*
	* In case we overwrite RAM region we set earlier in
	* head-nommu.S (which is cachable) all subsequent
	* data access till we setup RAM bellow would be done
	* with BG region (which is uncachable), thus we need
	* to clean and invalidate cache.
	*/
	bool need_flush = region == PMSAv7_RAM_REGION;

	if (!xip[i].size)
	continue;

	err \|= mpu_setup_region(region++, xip[i].base, ilog2(xip[i].size),
	PMSAv7_AP_PL1RO_PL0NA \| PMSAv7_RGN_NORMAL,
	xip[i].subreg, need_flush);
	}
	#endif

	/* RAM */
	for (i = 0; i < ARRAY_SIZE(mem); i++) {
	if (!mem[i].size)
	continue;

	err \|= mpu_setup_region(region++, mem[i].base, ilog2(mem[i].size),
	PMSAv7_AP_PL1RW_PL0RW \| PMSAv7_RGN_NORMAL,
	mem[i].subreg, false);
	}

	/* Vectors */
	#ifndef CONFIG_CPU_V7M
	err \|= mpu_setup_region(region++, vectors_base, ilog2(2 * PAGE_SIZE),
	PMSAv7_AP_PL1RW_PL0NA \| PMSAv7_RGN_NORMAL,
	0, false);
	#endif
	if (err) {
	panic("MPU region initialization failure! %d", err);
	} else {
	pr_info("Using ARMv7 PMSA Compliant MPU. "
	"Region independence: %s, Used %d of %d regions\n",
	mpu_iside_independent() ? "Yes" : "No",
	mpu_rgn_info.used, mpu_max_regions);
	}
	}