Subversion Repositories openrisc_2011-10-31

# ====================================================================

#

#      counters.cdl

#

#      configuration data related to the kernel counters and clocks

#

# ====================================================================

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# ====================================================================

######DESCRIPTIONBEGIN####

#

# Author(s):      jskov

# Original data:  nickg

# Contributors:

# Date:           1999-07-05

#

#####DESCRIPTIONEND####

#

# ====================================================================

cdl_option CYGVAR_KERNEL_COUNTERS_CLOCK {

    display       "Provide real-time clock"

    requires      CYGIMP_KERNEL_INTERRUPTS_DSRS

    default_value 1

    description   "

        On all current target systems the kernel can provide a

        real-time clock. This clock serves two purposes. First it is

        necessary to support clock and alarm related functions.

        Second it is needed to implement timeslicing in some of the

        schedulers including the mlqueue scheduler. If the

        application does not require any of these facilities then it

        is possible to disable the real time clock support

        completely."

}

cdl_component CYGPKG_KERNEL_COUNTERS_CLOCK_OVERRIDE {

    display       "Override default clock settings"

    requires      CYGVAR_KERNEL_COUNTERS_CLOCK

    default_value 0

    description   "

        The kernel has default settings for the clock interrupt

        frequency. These settings will vary from platform to

        platform, but typically there will be a 100 clock interrupts

        every second. It is possible to change this frequency, but

        it requires some knowledge of the target hardware."

    cdl_option CYGNUM_KERNEL_COUNTERS_CLOCK_OVERRIDE_PERIOD {

        display       "Clock hardware initialization value"

        flavor        data

        legal_values  1 to 0x7fffffff

        default_value 9999

        description   "

            During system initialization this value is used to initialize

            the clock hardware. The exact meaning of the value and the

            range of legal values therefore depends on the target hardware,

            and the hardware documentation should be consulted for further

            details. In addition the clock resolution numerator and

            denominator values should be updated. Typical values for

            this option would be 150000 on the MN10300 stdeval1 board,

            15625 on the tx39 jmr3904 board, and 20833 on the powerpc

            cogent board."

    }

    cdl_option CYGNUM_KERNEL_COUNTERS_CLOCK_OVERRIDE_NUMERATOR {

        display       "Clock resolution numerator"

        flavor        data

        legal_values  1 to 0x7fffffff

        default_value 1000000000

        description   "

            If a non-default clock interrupt frequency is used then it

            is necessary to specify the clock resolution explicitly.

            This resolution involves two separate values, the numerator

            and the denominator. The result of dividing the numerator by

            the denominator should correspond to the number of

            nanoseconds between clock interrupts. For example a

            numerator of 1000000000 and a denominator of 100 means that

            there are 10000000 nanoseconds (or 10 milliseconds) between

            clock interrupts. Expressing the resolution as a fraction

            should minimize clock drift even for frequencies that cannot

            be expressed as a simple integer. For example a frequency of

            60Hz corresponds to a clock resolution of 16666666.66...

            nanoseconds. This can be expressed accurately as 1000000000

            over 60."

    }

    cdl_option CYGNUM_KERNEL_COUNTERS_CLOCK_OVERRIDE_DENOMINATOR {

        display       "Clock resolution denominator"

        flavor        data

        legal_values  1 to 0x7fffffff

        default_value 100

        description   "

            If a non-default clock interrupt frequency is used then it

            is necessary to specify the clock resolution explicitly.

            This resolution involves two separate values, the numerator

            and the denominator. The result of dividing the numerator by

            the denominator should correspond to the number of

            nanoseconds between clock interrupts. For example a

            numerator of 1000000000 and a denominator of 100 means that

            there are 10000000 nanoseconds (or 10 milliseconds) between

            clock interrupts. Expressing the resolution as a fraction

            should minimize clock drift even for frequencies that cannot

            be expressed as a simple integer. For example a frequency of

            60Hz corresponds to a clock resolution of 16666666.66...

            nanoseconds. This can be expressed accurately as 1000000000

            over 60."

    }

}

cdl_interface CYGINT_KERNEL_COUNTERS {

    requires 1 == CYGINT_KERNEL_COUNTERS

    no_define

}

# NOTE: these option should really be a single enum.

cdl_option CYGIMP_KERNEL_COUNTERS_SINGLE_LIST {

    display       "Implement counters using a single list"

    default_value 1

    implements    CYGINT_KERNEL_COUNTERS

    description "

        There are two different implementations of the counter

        objects. The first implementation stores all alarms in a

        single linked list. The alternative implementation uses a

        table of linked lists. A single list is more efficient in

        terms of memory usage and is generally adequate when the

        application only makes use of a small number of alarms."

}

cdl_component CYGIMP_KERNEL_COUNTERS_MULTI_LIST {

    display       "Implement counters using a table of lists"

    default_value 0

    implements    CYGINT_KERNEL_COUNTERS

    description   "

        There are two different implementations of the counter

        objects. The first implementation stores all alarms in a

        single linked list. The alternative implementation uses a

        table of linked lists, with the size of the table being a

        separate configurable option. For more complicated

        operations it is better to have a table of lists since this

        reduces the amount of computation whenever the timer goes

        off. Assuming a table size of 8 (the default value) on

        average the timer code will only need to check 1/8 of the

        pending alarms instead of all of them."

    cdl_option CYGNUM_KERNEL_COUNTERS_MULTI_LIST_SIZE {

        display       "Size of counter list table"

        flavor        data

        legal_values  1 to 1024

        default_value 8

        description   "

            If counters are implemented using an array of linked lists

            then this option controls the size of the array. A larger

            size reduces the amount of computation that needs to take

            place whenever the timer goes off, but requires extra

            memory."

    }

}

cdl_option CYGIMP_KERNEL_COUNTERS_SORT_LIST {

    display       "Sort the counter list"

    default_value 0

    description   "

        Sorting the counter lists reduces the amount of work that

        has to be done when a counter tick is processed, since the

        next alarm to expire is always at the front of the list.

        However, it makes adding an alarm to the list more expensive

        since a search must be done for the correct place to put it.

        Many alarms are used to implement timeouts, which seldom trigger,

        so it is worthwhile optimizing this case. For this reason

        sorted list are disabled by default."

}

cdl_option CYGVAR_KERNEL_COUNTERS_CLOCK_LATENCY {

    display       "Measure real-time \[clock\] interrupt latency"

    requires      CYGVAR_KERNEL_COUNTERS_CLOCK

    default_value 0

    description   "

    Measure the interrupt latency as seen by the real-time clock

    timer interrupt.  This requires hardware support, defined by

    the HAL_CLOCK_LATENCY() macro."

}

cdl_option CYGVAR_KERNEL_COUNTERS_CLOCK_DSR_LATENCY {

    display       "Measure real-time \[clock\] DSR latency"

    requires      CYGVAR_KERNEL_COUNTERS_CLOCK_LATENCY

    default_value CYGVAR_KERNEL_COUNTERS_CLOCK_LATENCY

    description   "

          Measure the DSR latency as seen by the real-time clock

          timer interrupt.  This requires hardware support, defined by

          the HAL_CLOCK_LATENCY() macro."

}

cdl_option CYGNUM_KERNEL_COUNTERS_RTC_RESOLUTION {

    display       "RTC resolution"

    flavor        data

    calculated    { CYGPKG_KERNEL_COUNTERS_CLOCK_OVERRIDE ?                \

                     "{CYGNUM_KERNEL_COUNTERS_CLOCK_OVERRIDE_NUMERATOR,    \

                      CYGNUM_KERNEL_COUNTERS_CLOCK_OVERRIDE_DENOMINATOR}"  \

                    : "{CYGNUM_HAL_RTC_NUMERATOR, CYGNUM_HAL_RTC_DENOMINATOR}"}

    description   "

        This option automatically defines the tuple which is used to

        initialize the RTC resolution, consisting of a numerator and

        denominator.  For more information, see the option to

        override default clock settings

        (CYGPKG_KERNEL_COUNTERS_CLOCK_OVERRIDE) and associated options."

}

cdl_option CYGNUM_KERNEL_COUNTERS_RTC_PERIOD {

    display       "RTC period"

    flavor        data

    calculated    { CYGPKG_KERNEL_COUNTERS_CLOCK_OVERRIDE ?                \

                     "CYGNUM_KERNEL_COUNTERS_CLOCK_OVERRIDE_PERIOD"        \

                    : "CYGNUM_HAL_RTC_PERIOD"}

    description   "

        This option automatically defines the RTC period to be used in

        setting the system clock hardware.  For more information, see the

        option to override default clock settings

        (CYGPKG_KERNEL_COUNTERS_CLOCK_OVERRIDE) and associated options."

}

# EOF counters.cdl