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genode/base/include/util/mmio.h
Martin Stein 28f81c4a9c base: avoid shift warning in register array 
Fix #422
2013-01-08 11:36:52 +01:00

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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 _INCLUDE__UTIL__MMIO_H_
#define _INCLUDE__UTIL__MMIO_H_
/* Genode includes */
#include <util/register.h>
namespace Genode
{
/**
* A continuous MMIO region
*
* For correct behavior of the member functions of 'Mmio', a class that
* derives from one of the subclasses of 'Mmio' must not define members
* named 'Register_base', 'Bitfield_base', 'Register_array_base' or
* 'Array_bitfield_base'.
*/
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.
*
* For further details 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,
};
/*
* GCC 4.4, in contrast to GCC versions >= 4.5, can't
* select function templates like 'write(typename
* T::Register::access_t value)' through a given 'T'
* that, in this case, derives from 'Register<X, Y, Z>'.
* It seems this is due to the fact that 'T::Register'
* is a template. Thus we provide some kind of stamp
* that solely must not be redefined by the deriving
* class to ensure correct template selection.
*/
typedef Register<_OFFSET, _ACCESS_WIDTH, _STRICT_WRITE>
Register_base;
/**
* A region within a register
*
* \param _SHIFT Bit shift of the first bit within the
* compound register.
* \param _WIDTH bit width of the region
*
* For details see 'Genode::Register::Bitfield'.
*/
template <unsigned long _SHIFT, unsigned long _WIDTH>
struct Bitfield : public Genode::Register<ACCESS_WIDTH>::
template Bitfield<_SHIFT, _WIDTH>
{
/* analogous to 'Mmio::Register::Register_base' */
typedef Bitfield<_SHIFT, _WIDTH> Bitfield_base;
/* back reference to containing register */
typedef Register<_OFFSET, _ACCESS_WIDTH, _STRICT_WRITE>
Compound_reg;
};
};
/**
* An array of successive equally structured regions, called items
*
* \param _OFFSET Offset of the first item 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 item gets iterated
* successively.
* \param _ITEM_WIDTH bit width of an item
* \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.
*
* The array takes all inner structures, wich are covered by an
* item width and iterates them successively. 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 = (1ULL << ITEM_WIDTH) - 1,
};
/* analogous to 'Mmio::Register::Register_base' */
typedef Register_array<OFFSET, ACCESS_WIDTH, ITEMS,
ITEM_WIDTH, STRICT_WRITE>
Register_array_base;
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
*
* For details see 'Genode::Register::Bitfield'.
*/
template <unsigned long _SHIFT, unsigned long _SIZE>
struct Bitfield :
public Register<OFFSET, ACCESS_WIDTH, STRICT_WRITE>::
template Bitfield<_SHIFT, _SIZE>
{
/* analogous to 'Mmio::Register::Register_base' */
typedef Bitfield<_SHIFT, _SIZE> Array_bitfield_base;
/* 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; /* base address of targeted MMIO region */
/**
* Constructor
*
* \param mmio_base base address of targeted MMIO region
*/
inline Mmio(addr_t mmio_base) : base(mmio_base) { }
/*************************
** Access to registers **
*************************/
/**
* Get the address of the register 'T' typed as its access type
*/
template <typename T>
inline typename T::Register_base::access_t volatile * typed_addr() const
{
typedef typename T::Register_base Register;
typedef typename Register::access_t access_t;
return (access_t volatile *)(base + Register::OFFSET);
}
/**
* Read the register 'T'
*/
template <typename T>
inline typename T::Register_base::access_t read() const
{
typedef typename T::Register_base Register;
typedef typename Register::access_t access_t;
return _read<access_t>(Register::OFFSET);
}
/**
* Override the register 'T'
*/
template <typename T>
inline void
write(typename T::Register_base::access_t const value)
{
typedef typename T::Register_base Register;
typedef typename Register::access_t access_t;
_write<access_t>(Register::OFFSET, value);
}
/******************************************
** Access to bitfields within registers **
******************************************/
/**
* Read the bitfield 'T' of a register
*/
template <typename T>
inline typename T::Bitfield_base::Compound_reg::access_t
read() const
{
typedef typename T::Bitfield_base Bitfield;
typedef typename Bitfield::Compound_reg Register;
typedef typename Register::access_t access_t;
return Bitfield::get(_read<access_t>(Register::OFFSET));
}
/**
* Override to the bitfield 'T' of a register
*
* \param value value that shall be written
*/
template <typename T>
inline void
write(typename T::Bitfield_base::Compound_reg::access_t const value)
{
typedef typename T::Bitfield_base Bitfield;
typedef typename Bitfield::Compound_reg Register;
typedef typename Register::access_t access_t;
/* initialize the pattern written finally to the register */
access_t write_value;
if (Register::STRICT_WRITE)
{
/* apply the bitfield to an empty write pattern */
write_value = 0;
} else {
/* 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 arrays **
*******************************/
/**
* Read an item of the register array 'T'
*
* \param index index of the targeted item
*/
template <typename T>
inline typename T::Register_array_base::access_t
read(unsigned long const index) const
{
typedef typename T::Register_array_base Array;
typedef typename Array::access_t access_t;
/* reads outside the array return 0 */
if (index > Array::MAX_INDEX) return 0;
/* if item width equals access width we optimize the access */
off_t offset;
if (Array::ITEM_WIDTH == Array::ACCESS_WIDTH) {
offset = Array::OFFSET + (index << Array::ITEM_WIDTH_LOG2);
return _read<access_t>(offset);
/* access width and item width differ */
} else {
long unsigned shift;
Array::access_dest(offset, shift, index);
return (_read<access_t>(offset) >> shift) &
Array::ITEM_MASK;
}
}
/**
* Override an item of the register array 'T'
*
* \param value value that shall be written
* \param index index of the targeted item
*/
template <typename T>
inline void
write(typename T::Register_array_base::access_t const value,
unsigned long const index)
{
typedef typename T::Register_array_base Array;
typedef typename Array::access_t access_t;
/* ignore writes outside the array */
if (index > Array::MAX_INDEX) return;
/* optimize the access if item width equals access width */
off_t offset;
if (Array::ITEM_WIDTH == Array::ACCESS_WIDTH) {
offset = Array::OFFSET +
(index << Array::ITEM_WIDTH_LOG2);
_write<access_t>(offset, value);
/* access width and item width differ */
} else {
long unsigned shift;
Array::access_dest(offset, shift, index);
/* insert new value into old register value */
access_t write_value;
if (Array::STRICT_WRITE)
{
/* apply bitfield to an empty write pattern */
write_value = 0;
} else {
/* apply bitfield to the old register value */
write_value = _read<access_t>(offset);
write_value &= ~(Array::ITEM_MASK << shift);
}
/* apply bitfield value and override register */
write_value |= (value & Array::ITEM_MASK) << shift;
_write<access_t>(offset, write_value);
}
}
/*****************************************************
** Access to bitfields within register array items **
*****************************************************/
/**
* Read the bitfield 'T' of a register array
*
* \param index index of the targeted item
*/
template <typename T>
inline typename T::Array_bitfield_base::Compound_array::access_t
read(unsigned long const index) const
{
typedef typename T::Array_bitfield_base Bitfield;
typedef typename Bitfield::Compound_array Array;
return Bitfield::get(read<Array>(index));
}
/**
* Override the bitfield 'T' of a register array
*
* \param value value that shall be written
* \param index index of the targeted array item
*/
template <typename T>
inline void
write(typename T::Array_bitfield_base::Compound_array::access_t const value,
long unsigned const index)
{
typedef typename T::Array_bitfield_base Bitfield;
typedef typename Bitfield::Compound_array Array;
typedef typename Array::access_t access_t;
/* initialize the pattern written finally to the register */
access_t write_value;
if (Array::STRICT_WRITE)
{
/* apply the bitfield to an empty write pattern */
write_value = 0;
} else {
/* apply the bitfield to the old register value */
write_value = read<Array>(index);
Bitfield::clear(write_value);
}
/* apply bitfield value and override register */
Bitfield::set(write_value, value);
write<Array>(write_value, index);
}
/*********************************
** Polling for bitfield states **
*********************************/
/**
* Interface for delaying the execution of a calling thread
*/
struct Delayer
{
/**
* Delay execution of the caller for 'us' microseconds
*/
virtual void usleep(unsigned us) = 0;
};
/**
* Wait until bitfield 'T' 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 T>
inline bool
wait_for(typename T::Bitfield_base::Compound_reg::access_t const value,
Delayer & delayer,
unsigned max_attempts = 500,
unsigned us = 1000)
{
typedef typename T::Bitfield_base Bitfield;
for (unsigned i = 0; i < max_attempts; i++, delayer.usleep(us))
{
if (read<Bitfield>() == value) return true;
}
return false;
}
};
}
#endif /* _INCLUDE__UTIL__MMIO_H_ */
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