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genode/repos/base/include/util/register_set.h
Martin Stein ecbb7534b9 register set: make noncopyable 
If a register set gets copied, the '_plain_access' of the copy references
the plain access object of the original object.

Ref #2196
2017-03-15 12:32:23 +01:00

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/*
* \brief Set of fine-grained and typesafe accessible registers with offsets
* \author Martin stein
* \date 2011-10-26
*/
/*
* Copyright (C) 2011-2017 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU Affero General Public License version 3.
*/
#ifndef _INCLUDE__UTIL__REGISTER_SET_H_
#define _INCLUDE__UTIL__REGISTER_SET_H_
/* Genode includes */
#include <util/register.h>
#include <util/noncopyable.h>
#include <base/exception.h>
namespace Genode {
struct Register_set_plain_access;
template <typename> class Register_set;
}
/**
* Interface declaration for implementations of plain access to a register set
*
* This class enables us to use the bit and offset logic of the Register_set
* template with different plain access implementations and, at the same time,
* keep the plain access implementation invisible at the front-end. The class
* circumvents the fact that we can't have virtual method templates nor
* template friends. The plain access implementation should keep its methods
* private and declare this class as friend. It is then handed over as
* argument to the Register_set template.
*/
struct Genode::Register_set_plain_access
{
/**
* Write on plain integer level to a register of the set
*
* \param ACCESS_T plain integer type of the register to access
* \param IMPLEMENTATION implementation of access on the plain integer level
* \param impl instance of the access implementation
* \param offset register offset
* \param value value to be written to the register
*/
template <typename ACCESS_T, typename IMPLEMENTATION>
static inline
void write(IMPLEMENTATION &impl, off_t const offset, ACCESS_T const value) {
impl.template _write<ACCESS_T>(offset, value); }
/**
* Read on plain integer level from a register of the set
*
* \param ACCESS_T plain integer type of the register to access
* \param IMPLEMENTATION implementation of access on the plain integer level
* \param impl instance of the access implementation
* \param offset register offset
* \param value value to be written to the register
*/
template <typename ACCESS_T, typename IMPLEMENTATION>
static inline ACCESS_T read(IMPLEMENTATION &impl, off_t const offset) {
return impl.template _read<ACCESS_T>(offset); }
};
/**
* Set of fine-grained and typesafe accessible registers with offsets
*
* \param PLAIN_ACCESS Implementation of access on the plain integer level.
* Should derive from the Register_set_plain_access
* interface.
*
* A register set consists of individual registers and register arrays with
* different offsets. The class receives the specific implementation of plain
* access as argument. This way, it can be used with different types of IO
* (MMIO, I2C, Port IO, ...) . For correct behavior of the 'Register_set'
* methods, a class that derives from one of the subclasses of 'Register_set'
* must not define members named 'Register_base', 'Bitfield_base',
* 'Register_array_base' or 'Array_bitfield_base'.
*/
template <typename PLAIN_ACCESS>
class Genode::Register_set : Noncopyable
{
private:
using Plain_access = Register_set_plain_access;
enum { BYTE_WIDTH_LOG2 = 3, BYTE_WIDTH = 1 << BYTE_WIDTH_LOG2 };
/**
* Return wether one IO condition is met
*
* \param CONDITION A condition subtype of Register, Bitfield, or
* such (for example the Bitfield::Equal type)
* \param condition the condition instance
*/
template <typename CONDITION>
inline bool _conditions_met(CONDITION condition) {
return condition.met(read<typename CONDITION::Object>()); }
/**
* Return wether a list of IO conditions is met
*
* \param CONDITION The type of the head of the condition list.
* A condition subtype of Register, Bitfield, or
* such (for example the Bitfield::Equal type).
* \param CONDITIONS The types of the tail of the condition list.
* condition subtypes of Register, Bitfield, or
* such (for example the Bitfield::Equal type)
* \param head the condition instance
*/
template <typename CONDITION, typename... CONDITIONS>
inline bool _conditions_met(CONDITION head, CONDITIONS... tail) {
return _conditions_met(head) ? _conditions_met(tail...) : false; }
/**
* This template equips registers/bitfields with conditions for polling
*
* \param T register/bitfield type that the conditions shall be about
*
* The condition subtypes enable us to poll for a variable amount of
* conditions for different registers/bitfields at once. They are used
* as input to the 'wait_for' template.
*/
template <typename T>
struct Conditions
{
/**
* Condition that the register/bitfield equals a value
*/
class Equal
{
private:
typedef typename T::access_t access_t;
access_t const _reference_val;
public:
typedef T Object;
/**
* Constructor
*
* \param reference_val reference value
*/
explicit Equal(access_t const reference_val)
: _reference_val(reference_val) { }
/**
* Return whether the condition is met
*
* \param actual_val actual regster/bitfield value
*/
bool met(access_t const actual_val) const {
return _reference_val == actual_val; }
};
};
PLAIN_ACCESS &_plain_access;
public:
/**
* An integer like region at a specific place within a register set
*
* \param _OFFSET Offset of the region in the register set
* \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>,
public Conditions<Register<_OFFSET, _ACCESS_WIDTH, _STRICT_WRITE> >
{
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;
typedef typename Genode::Register<_ACCESS_WIDTH>::access_t
access_t;
/**
* 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>,
public Conditions<Bitfield<_SHIFT, _WIDTH> >
{
/* analogous to 'Register_set::Register::Register_base' */
typedef Bitfield<_SHIFT, _WIDTH> Bitfield_base;
/* back reference to containing register */
typedef Register<_OFFSET, _ACCESS_WIDTH, _STRICT_WRITE>
Compound_reg;
typedef Compound_reg::access_t access_t;
};
};
/**
* An array of successive equally structured regions, called items
*
* \param _OFFSET Offset of the first item in the register set
* \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_width<_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 'Register_set::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 bit region 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 'Register_set::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
* \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 dst(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;
}
/**
* Calc destination of a simple array-item access without shift
*
* \param offset gets overridden with the offset of the the
* access destination
* \param index index of the targeted array item
*/
static inline void simple_dst(off_t & offset,
unsigned long const index)
{
offset = (index << ITEM_WIDTH_LOG2) >> BYTE_WIDTH_LOG2;
offset += OFFSET;
}
};
/**
* Constructor
*
* \param plain_access implementation of plain register access
*/
Register_set(PLAIN_ACCESS &plain_access)
: _plain_access(plain_access) { }
/*************************
** Access to registers **
*************************/
/**
* 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 Plain_access::read<access_t>(_plain_access,
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;
Plain_access::write<access_t>(_plain_access, 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(Plain_access::read<access_t>(_plain_access,
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) {
Array::simple_dst(offset, index);
return Plain_access::read<access_t>(_plain_access, offset);
/* access width and item width differ */
} else {
long unsigned shift;
Array::dst(offset, shift, index);
return (Plain_access::read<access_t>(_plain_access, 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) {
Array::simple_dst(offset, index);
Plain_access::write<access_t>(_plain_access, offset, value);
/* access width and item width differ */
} else {
long unsigned shift;
Array::dst(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 = Plain_access::read<access_t>(_plain_access,
offset);
write_value &= ~(Array::ITEM_MASK << shift);
}
/* apply bitfield value and override register */
write_value |= (value & Array::ITEM_MASK) << shift;
Plain_access::write<access_t>(_plain_access, 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);
}
/***********************
** Access to bitsets **
***********************/
/**
* Read bitset 'T' (composed of 2 parts)
*/
template <typename T>
inline typename T::Bitset_2_base::access_t const read()
{
typedef typename T::Bitset_2_base::Bits_0 Bits_0;
typedef typename T::Bitset_2_base::Bits_1 Bits_1;
typedef typename T::Bitset_2_base::access_t access_t;
enum { V1_SHIFT = Bits_0::BITFIELD_WIDTH };
access_t const v0 = read<Bits_0>();
access_t const v1 = read<Bits_1>();
return v0 | (v1 << V1_SHIFT);
}
/**
* Override bitset 'T' (composed of 2 parts)
*
* \param v value that shall be written
*/
template <typename T>
inline void write(typename T::Bitset_2_base::access_t v)
{
typedef typename T::Bitset_2_base::Bits_0 Bits_0;
typedef typename T::Bitset_2_base::Bits_1 Bits_1;
write<Bits_0>(v);
write<Bits_1>(v >> Bits_0::BITFIELD_WIDTH);
}
/**
* Read bitset 'T' (composed of 3 parts)
*/
template <typename T>
inline typename T::Bitset_3_base::access_t const read()
{
typedef typename T::Bitset_3_base::Bits_0 Bits_0;
typedef typename T::Bitset_3_base::Bits_1 Bits_1;
typedef typename T::Bitset_3_base::Bits_2 Bits_2;
typedef typename T::Bitset_3_base::access_t access_t;
enum {
BITS_0_WIDTH = Bits_0::BITFIELD_WIDTH,
BITS_1_WIDTH = Bits_1::BITFIELD_WIDTH,
V1_SHIFT = BITS_0_WIDTH + BITS_1_WIDTH,
};
access_t const v0 = read<Bitset_2<Bits_0, Bits_1> >();
access_t const v1 = read<Bits_2>();
return v0 | (v1 << V1_SHIFT);
}
/**
* Override bitset 'T' (composed of 3 parts)
*
* \param v value that shall be written
*/
template <typename T>
inline void write(typename T::Bitset_3_base::access_t v)
{
typedef typename T::Bitset_3_base::Bits_0 Bits_0;
typedef typename T::Bitset_3_base::Bits_1 Bits_1;
typedef typename T::Bitset_3_base::Bits_2 Bits_2;
write<Bitset_2<Bits_0, Bits_1> >(v);
write<Bits_2>(v >> (Bits_0::BITFIELD_WIDTH +
Bits_1::BITFIELD_WIDTH));
}
/*********************************
** Polling for bitfield states **
*********************************/
struct Polling_timeout : Exception { };
struct Attempts
{
unsigned value;
explicit Attempts(unsigned value) : value(value) { }
};
struct Microseconds
{
unsigned value;
explicit Microseconds(unsigned value) : value(value) { }
};
/**
* 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 a list of IO conditions is met
*
* \param CONDITIONS Types of the of conditions in the condition
* list. Condition subtypes of the IO types. For
* example the Bitfield::Equal type.
* \param attempts maximum number of probing attempts
* \param us number of microseconds between attempts
* \param delayer Sleeping facility to be used when the
* conditions are not met
* \param conditions condition list
*
* \throw Polling_timeout
*/
template <typename... CONDITIONS>
inline void wait_for(Attempts attempts,
Microseconds us,
Delayer &delayer,
CONDITIONS... conditions)
{
for (unsigned i = 0; i < attempts.value; i++,
delayer.usleep(us.value))
{
if (_conditions_met(conditions...)) {
return; }
}
throw Polling_timeout();
}
/**
* Shortcut for 'wait_for' with 'attempts = 500' and 'us = 1000'
*/
template <typename... CONDITIONS>
inline void wait_for(Delayer &delayer, CONDITIONS... conditions)
{
wait_for<CONDITIONS...>(Attempts(500), Microseconds(1000),
delayer, conditions...);
}
/**
* Wait until register '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 register probing attempts
* \param us number of microseconds between attempts
*
* \noapi
* \deprecated use 'template <typename... CONDITIONS> wait_for'
*/
template <typename T>
inline bool
wait_for(typename T::Register_base::access_t const value,
Delayer & delayer,
unsigned max_attempts = 500,
unsigned us = 1000) __attribute__ ((deprecated));
/**
* 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
*
* \noapi
* \deprecated use 'template <typename... CONDITIONS> wait_for'
*/
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) __attribute__ ((deprecated));
};
template <typename PLAIN_ACCESS>
template <typename T>
bool Genode::Register_set<PLAIN_ACCESS>::
wait_for(typename T::Register_base::access_t const value,
Delayer &delayer,
unsigned max_attempts,
unsigned us)
{
typedef typename T::Register_base Register;
for (unsigned i = 0; i < max_attempts; i++, delayer.usleep(us))
{
if (read<Register>() == value) {
return true; }
}
return false;
}
template <typename PLAIN_ACCESS>
template <typename T>
bool Genode::Register_set<PLAIN_ACCESS>::
wait_for(typename T::Bitfield_base::Compound_reg::access_t const value,
Delayer &delayer,
unsigned max_attempts,
unsigned us)
{
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__REGISTER_SET_H_ */
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