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cfda8ac4ae
genode/base/include/util/mmio.h
Norman Feske cfda8ac4ae Add bitfield polling support to MMIO framework
2012-07-09 15:07:32 +02:00

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/*
* \brief Generic MMIO access framework
* \author Martin stein
* \date 2011-10-26
*/
/*
* Copyright (C) 2011-2012 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#ifndef _BASE__INCLUDE__UTIL__MMIO_H_
#define _BASE__INCLUDE__UTIL__MMIO_H_
/* Genode includes */
#include <util/register.h>
namespace Genode
{
/**
* A continuous MMIO region
*/
class Mmio
{
protected:
/**
* Write typed 'value' to MMIO base + 'o'
*/
template <typename _ACCESS_T>
inline void _write(off_t const o, _ACCESS_T const value) {
*(_ACCESS_T volatile *)((addr_t)base + o) = value; }
/**
* Read typed from MMIO base + 'o'
*/
template <typename _ACCESS_T>
inline _ACCESS_T _read(off_t const o) const {
return *(_ACCESS_T volatile *)((addr_t)base + o); }
public:
enum { BYTE_WIDTH_LOG2 = 3, BYTE_WIDTH = 1 << BYTE_WIDTH_LOG2 };
/**
* An integer like region within a MMIO region.
*
* \param _OFFSET Offset of the region relative to the
* base of the compound MMIO
* \param _ACCESS_WIDTH Bit width of the region, for a list of
* supported widths see 'Genode::Register'
* \param _STRICT_WRITE If set to 0, when writing a bitfield, we
* read the register value, update the bits
* on it, and write it back to the register.
* If set to 1 we take an empty register
* value instead, apply the bitfield on it,
* and write it to the register. This can
* be useful if you have registers that have
* different means on reads and writes.
*
* \detail See 'Genode::Register'
*/
template <off_t _OFFSET, unsigned long _ACCESS_WIDTH,
bool _STRICT_WRITE = false>
struct Register : public Genode::Register<_ACCESS_WIDTH>
{
enum {
OFFSET = _OFFSET,
ACCESS_WIDTH = _ACCESS_WIDTH,
STRICT_WRITE = _STRICT_WRITE,
};
/**
* A region within a register
*
* \param _SHIFT Bit shift of the first bit within the
* compound register
* \param _WIDTH Bit width of the region
*
* \detail See 'Genode::Register::Bitfield'
*/
template <unsigned long _SHIFT, unsigned long _WIDTH>
struct Bitfield :
public Genode::Register<ACCESS_WIDTH>::template Bitfield<_SHIFT, _WIDTH>
{
/* Back reference to containing register */
typedef Register<OFFSET, ACCESS_WIDTH, STRICT_WRITE> Compound_reg;
};
};
/**
* An array of successive equally structured regions
*
* \param _OFFSET Offset of the first region relative to
* the base of the compound MMIO.
* \param _ACCESS_WIDTH Bit width of a single access, must be at
* least the item width.
* \param _ITEMS How many times the region gets iterated
* successive
* \param _ITEM_WIDTH Bit width of a region
* \param _STRICT_WRITE If set to 0, when writing a bitfield, we
* read the register value, update the bits
* on it, and write it back to the register.
* If set to 1, we take an empty register
* value instead, apply the bitfield on it,
* and write it to the register. This can
* be useful if you have registers that have
* different means on reads and writes.
* Please note that ACCESS_WIDTH is decisive
* for the range of such strictness.
*
* \detail The array takes all inner structures, wich are covered
* by an item width and iterates them successive. Such
* structures that are partially exceed an item range are
* read and written also partially. Structures that are
* completely out of the item range are read as '0' and
* trying to overwrite them has no effect. The array is
* not limited to its access width, it extends to the
* memory region of its successive items. Trying to read
* out read with an item index out of the array range
* returns '0', trying to write to such indices has no
* effect
*/
template <off_t _OFFSET, unsigned long _ACCESS_WIDTH,
unsigned long _ITEMS, unsigned long _ITEM_WIDTH,
bool _STRICT_WRITE = false>
struct Register_array : public Register<_OFFSET, _ACCESS_WIDTH,
_STRICT_WRITE>
{
typedef
typename Trait::Uint_type<_ACCESS_WIDTH>::template Divisor<_ITEM_WIDTH>
Item;
enum {
STRICT_WRITE = _STRICT_WRITE,
OFFSET = _OFFSET,
ACCESS_WIDTH = _ACCESS_WIDTH,
ITEMS = _ITEMS,
ITEM_WIDTH = _ITEM_WIDTH,
ITEM_WIDTH_LOG2 = Item::WIDTH_LOG2,
MAX_INDEX = ITEMS - 1,
ITEM_MASK = (1 << ITEM_WIDTH) - 1,
};
typedef
typename Register<OFFSET, ACCESS_WIDTH, STRICT_WRITE>::access_t
access_t;
/**
* A bitregion within a register array item
*
* \param _SHIFT Bit shift of the first bit within an item
* \param _WIDTH Bit width of the region
*
* \detail See 'Genode::Register::Bitfield'
*/
template <unsigned long _SHIFT, unsigned long _SIZE>
struct Bitfield :
public Register<OFFSET, ACCESS_WIDTH, STRICT_WRITE>::template Bitfield<_SHIFT, _SIZE>
{
/* Back reference to containing register array */
typedef Register_array<OFFSET, ACCESS_WIDTH, ITEMS,
ITEM_WIDTH, STRICT_WRITE>
Compound_array;
};
/**
* Calculate destination of an array-item access
*
* \param offset Gets overridden with the offset of the
* access type instance, that contains the
* access destination, relative to the MMIO
* base
* \param shift Gets overridden with the shift of the
* destination within the access type instance
* targeted by 'offset'
* \param index Index of the targeted array item
*/
static inline void access_dest(off_t & offset,
unsigned long & shift,
unsigned long const index)
{
unsigned long const bit_off = index << ITEM_WIDTH_LOG2;
offset = (off_t) ((bit_off >> BYTE_WIDTH_LOG2)
& ~(sizeof(access_t)-1) );
shift = bit_off - ( offset << BYTE_WIDTH_LOG2 );
offset += OFFSET;
}
};
addr_t const base;
/**
* Constructor
*/
inline Mmio(addr_t mmio_base) : base(mmio_base) { }
/*************************
** Access to registers **
*************************/
/**
* Typed address of register 'REGISTER'
*/
template <typename REGISTER>
inline typename REGISTER::access_t volatile * typed_addr() const {
return (typename REGISTER::access_t volatile *)
base + REGISTER::OFFSET; }
/**
* Read the whole register 'REGISTER'
*/
template <typename REGISTER>
inline typename REGISTER::access_t read() const {
return _read<typename REGISTER::access_t>(REGISTER::OFFSET); }
/**
* Write 'value' to the register 'REGISTER'
*/
template <typename REGISTER>
inline void write(typename REGISTER::access_t const value) {
_write<typename REGISTER::access_t>(REGISTER::OFFSET, value); }
/******************************************
** Access to bitfields within registers **
******************************************/
/**
* Read the bitfield 'BITFIELD'
*/
template <typename BITFIELD>
inline typename BITFIELD::Compound_reg::access_t read() const;
/**
* Write value to the bitfield 'BITFIELD'
*/
template <typename BITFIELD>
inline void
write(typename BITFIELD::Compound_reg::access_t const value);
/*******************************
** Access to register arrays **
*******************************/
/**
* Read the whole item 'index' of the array 'REGISTER_ARRAY'
*/
template <typename REGISTER_ARRAY>
inline typename REGISTER_ARRAY::access_t
read(unsigned long const index) const;
/**
* Write 'value' to item 'index' of the array 'REGISTER_ARRAY'
*/
template <typename REGISTER_ARRAY>
inline void write(typename REGISTER_ARRAY::access_t const value,
unsigned long const index);
/*****************************************************
** Access to bitfields within register array items **
*****************************************************/
/**
* Read the bitfield 'ARRAY_BITFIELD' of item 'index' of the
* compound reg array
*/
template <typename ARRAY_BITFIELD>
inline typename ARRAY_BITFIELD::Compound_array::access_t
read(unsigned long const index) const;
/**
* Write 'value' to bitfield 'ARRAY_BITFIELD' of item 'index' of
* the compound reg array
*/
template <typename ARRAY_BITFIELD>
inline void
write(typename ARRAY_BITFIELD::Compound_array::access_t const value,
long unsigned const index);
/*********************************
** Polling for bitfield states **
*********************************/
/**
* Interface for delaying the execution of a calling thread
*/
struct Delayer
{
/**
* Delay the execution of the caller for the specified amount
* of microseconds
*/
virtual void usleep(unsigned us) = 0;
};
/**
* Wait until the 'BITFIELD' contains the specified 'value'
*
* \param value value to wait for
* \param delayer sleeping facility to be used when the
* value is not reached yet
* \param max_attempts number of bitfield probing attempts
* \param us number of microseconds between attempts
*/
template <typename BITFIELD>
inline bool
wait_for(typename BITFIELD::Compound_reg::access_t const value,
Delayer &delayer,
unsigned max_attempts = 500,
unsigned us = 1000)
{
for (unsigned i = 0; i < max_attempts; i++, delayer.usleep(us))
if (read<BITFIELD>() == value)
return true;
return false;
}
};
}
/******************************************
** Access to bitfields within registers **
******************************************/
template <typename BITFIELD>
typename BITFIELD::Compound_reg::access_t Genode::Mmio::read() const
{
typedef typename BITFIELD::Compound_reg Register;
typedef typename Register::access_t access_t;
return BITFIELD::get(_read<access_t>(Register::OFFSET));
}
template <typename BITFIELD>
void Genode::Mmio::write(typename BITFIELD::Compound_reg::access_t const value)
{
/* Initialize the pattern that is written finally to the register */
typedef typename BITFIELD::Compound_reg Register;
typename Register::access_t write_value;
if (Register::STRICT_WRITE)
{
/* We must only apply the bitfield to an empty write pattern */
write_value = 0;
} else {
/* We've got to apply the bitfield to the old register value */
write_value = read<Register>();
BITFIELD::clear(write_value);
}
/* Apply bitfield value and override register */
BITFIELD::set(write_value, value);
write<Register>(write_value);
}
/************************************
** Access to register array items **
************************************/
template <typename REGISTER_ARRAY>
typename REGISTER_ARRAY::access_t
Genode::Mmio::read(unsigned long const index) const
{
/* Reads outside the array return 0 */
if (index > REGISTER_ARRAY::MAX_INDEX) return 0;
/* If item width equals access width we optimize the access */
off_t offset;
if (REGISTER_ARRAY::ITEM_WIDTH == REGISTER_ARRAY::ACCESS_WIDTH) {
offset = REGISTER_ARRAY::OFFSET
+ (index << REGISTER_ARRAY::ITEM_WIDTH_LOG2);
return _read<typename REGISTER_ARRAY::access_t>(offset);
/* Access width and item width differ */
} else {
long unsigned shift;
REGISTER_ARRAY::access_dest(offset, shift, index);
return (_read<typename REGISTER_ARRAY::access_t>(offset) >> shift)
& REGISTER_ARRAY::ITEM_MASK;
}
}
template <typename REGISTER_ARRAY>
void Genode::Mmio::write(typename REGISTER_ARRAY::access_t const value,
unsigned long const index)
{
/* Writes outside the array are ignored */
if (index > REGISTER_ARRAY::MAX_INDEX) return;
/* If item width equals access width we optimize the access */
off_t offset;
if (REGISTER_ARRAY::ITEM_WIDTH == REGISTER_ARRAY::ACCESS_WIDTH) {
offset = REGISTER_ARRAY::OFFSET
+ (index << REGISTER_ARRAY::ITEM_WIDTH_LOG2);
_write<typename REGISTER_ARRAY::access_t>(offset, value);
/* Access width and item width differ */
} else {
long unsigned shift;
REGISTER_ARRAY::access_dest(offset, shift, index);
/* Insert new value into old register value */
typename REGISTER_ARRAY::access_t write_value;
if (REGISTER_ARRAY::STRICT_WRITE)
{
/* We must only apply the bitfield to an empty write pattern */
write_value = 0;
} else {
/* We've got to apply the bitfield to the old register value */
write_value = _read<typename REGISTER_ARRAY::access_t>(offset);
write_value &= ~(REGISTER_ARRAY::ITEM_MASK << shift);
}
/* Apply bitfield value and override register */
write_value |= (value & REGISTER_ARRAY::ITEM_MASK) << shift;
_write<typename REGISTER_ARRAY::access_t>(offset, write_value);
}
}
/*****************************************************
** Access to bitfields within register array items **
*****************************************************/
template <typename ARRAY_BITFIELD>
void
Genode::Mmio::write(typename ARRAY_BITFIELD::Compound_array::access_t const value,
long unsigned const index)
{
/* Initialize the pattern that is finally written to the register */
typedef typename ARRAY_BITFIELD::Compound_array Register_array;
typename Register_array::access_t write_value;
if (Register_array::STRICT_WRITE)
{
/* We must only apply the bitfield to an empty write pattern */
write_value = 0;
} else {
/* We've got to apply the bitfield to the old register value */
write_value = read<Register_array>(index);
ARRAY_BITFIELD::clear(write_value);
}
/* Apply bitfield value and override register */
ARRAY_BITFIELD::set(write_value, value);
write<Register_array>(write_value, index);
}
template <typename ARRAY_BITFIELD>
typename ARRAY_BITFIELD::Compound_array::access_t
Genode::Mmio::read(long unsigned const index) const
{
typedef typename ARRAY_BITFIELD::Compound_array Array;
typedef typename Array::access_t access_t;
return ARRAY_BITFIELD::get(read<Array>(index));
}
#endif /* _BASE__INCLUDE__UTIL__MMIO_H_ */
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