NAME¶
mk48txx
—
Mostek time-of-day clock driver
SYNOPSIS¶
#include
<sys/eventhandler.h>
#include
<sys/lock.h>
#include
<sys/mutex.h>
#include
<dev/mk48txx/mk48txxvar.h>
To compile this driver into the kernel, place the following line in your kernel
configuration file:
device
mk48txx
DESCRIPTION¶
The
mk48txx
driver is a back-end for several
models of Mostek time-of-day clock chips. It provides access methods to
retrieve and set date and time for use with the
“
clock
” KOBJ interface.
To tie an instance of this device to the system, use the
mk48txx_attach
() function and the
mk48txx_softc structure defined as follows:
int
mk48txx_attach
(
device_t
dev)
typedef uint8_t (*mk48txx_nvrd_t)(device_t dev, int off);
typedef void (*mk48txx_nvwr_t)(device_t dev, int off, uint8_t v);
struct mk48txx_softc {
struct resource sc_res;
struct mtx sc_mtx;
eventhandler_tag sc_wet;
const char *sc_model;
bus_size_t sc_nvramsz;
bus_size_t sc_clkoffset;
u_int sc_year0;
u_int sc_flag;
mk48txx_nvrd_t sc_nvrd;
mk48txx_nvwr_t sc_nvwr;
};
- sc_res
- The bus resource used for accessing the chip's non-volatile memory
(including the clock registers), which must be supplied by the front-end
when using the default access methods (see below). Otherwise this member
is optional.
- sc_mtx
- The hardware mutex used when accessing the chip's non-volatile memory
(including the clock registers), which must be initialized with
MTX_DEF
by the front-end.
- sc_wet
- The event handler tag for the watchdog functionality, which is registered
by the
mk48txx_attach
() function if
supported by the chip and specified as part of the machine-dependent
features (see below).
- sc_model
- The chip model which this instance should serve. This member must be set
to one of “mk48t02”, “mk48t08”,
“mk48t18”, or “mk48t59” by the front-end.
- sc_nvramsz
- The size of the non-volatile RAM in the Mostek chip, which is set by the
mk48txx_attach
() function.
- sc_clkoffset
- The offset into the control registers of the Mostek chip, which is set by
the
mk48txx_attach
() function.
- sc_year0
- The year offset to be used with the ‘year’ counter of the
clock, which must be set by the front-end. This value is generally
dependent on the system configuration in which the clock device is
mounted. For instance, on Sun Microsystems machines the convention is to
have clock's two-digit year represent the year since 1968.
- sc_flag
- This flag is used to specify machine-dependent features. The following
flags are supported:
MK48TXX_NO_CENT_ADJUST
- If the resulting date retrieved with the
“
clock_gettime() method
” would
be earlier than January 1, 1970, the driver will assume that the
chip's year counter actually represents a year in the 21st century.
This behavior can be overridden by setting this flag, which causes the
mk48txx
driver to respect the
clock's century bit instead.
MK48TXX_WDOG_REGISTER
- When this flag is set, the
mk48txx
driver will register as a watchdog via the interface defined in
watchdog(9) if supported by the specific
chip model.
MK48TXX_WDOG_ENABLE_WDS
- When this flag is set, the
mk48txx
driver will set the watchdog steering (WDS) bit when enabling the
watchdog functionality of the chip. enabled (see the chip
documentation for further information regarding the WDS bit).
- sc_nvread
-
- sc_nvwrite
- These members specify the access methods for reading respectively writing
clock device registers. The default, when
NULL
is passed as an access method, is
to access the chip memory (and clock registers) as if they were
direct-mapped using the specified bus resource.
Otherwise, the driver will call the respective function supplied by the
front-end to perform the access, passing it the offset
off of the chip memory (or clock
register) location to be read from or written to, respectively.
HARDWARE¶
The following models are supported:
- Mostek MK48T02
-
- Mostek MK48T08
-
- Mostek MK48T18
-
- Mostek MK48T59
-
SEE ALSO¶
intro(4),
watchdog(9)
HISTORY¶
The
mk48txx
driver appeared in
NetBSD 1.5. The first
FreeBSD
version to include it was
FreeBSD 5.0.
AUTHORS¶
The
mk48txx
driver was written for
NetBSD by
Paul
Kranenburg ⟨pk@NetBSD.org⟩. It was ported to
FreeBSD by
Thomas
Moestl ⟨tmm@FreeBSD.org⟩ and later on improved by
Marius Strobl
⟨marius@FreeBSD.org⟩.