NAME
mk48txx —
Mostek time-of-day clock
driver
SYNOPSIS
#include <dev/ic/mk48txxreg.h>
#include <dev/ic/mk48txxvar.h>
define mk48txx
file dev/ic/mk48txx.c mk48txx
DESCRIPTION
The
mk48txx driver provides access to several models of Mostek
time-of-day clock chips. Access methods to retrieve and set date and time are
provided through the
TODR interface defined in
todr(9).
To tie an instance of this device to the system, use the
mk48txx_attach() function and the mk48txx_softc structure
defined as follows:
void
mk48txx_attach(
struct mk48txx_softc *)
typedef uint8_t (*mk48txx_nvrd_t)(struct mk48txx_softc *, int off);
typedef void (*mk48txx_nvwr_t)(struct mk48txx_softc *, int off,
uint8_t datum);
struct mk48txx_softc {
struct device sc_dev;
bus_space_tag_t sc_bst;
bus_space_handle_t sc_bsh;
struct todr_chip_handle sc_handle;
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_bst
-
- sc_bsh
- Specify bus space access to the chip's non-volatile memory
(including the clock registers).
-
-
- sc_handle
- TODR handle passed to the todr_attach()
function to register todr(9)
interface.
-
-
- sc_model
- The chip model which this instance should serve. Must be
one of “mk48t02”, “mk48t08”,
“mk48t18”, or “mk48t59”.
-
-
- sc_nvramsz
- Size of non-volatile RAM in the Mostek chip. This value is
set by mk48txx_attach().
-
-
- sc_clkoffset
- Offset into the control registers of the Mostek chip. This
value is set by mk48txx_attach().
-
-
- sc_year0
- The actual year represented by the clock's
‘year’ counter. This 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 1968.
-
-
- sc_flag
- This flag is used to specify machine-dependent
features.
-
-
- sc_nvread
-
- sc_nvwrite
- Specify alternate access methods for reading resp. 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 with using the specified bus
space.
Otherwise, the driver will call the respective function to perform the
access, passing it the specified bus space and the offset
off of the chip memory (or clock register) location
to be read from or written to, respectively.
Note that if the resulting date retrieved with the todr_gettime() method is
earlier that January 1, 1970, the driver will assume that the chip's year
counter actually represents a year in the 21st century. This behaviour can be
overridden by setting the
MK48TXX_NO_CENT_ADJUST flag in
sc_flag.
HARDWARE
The following models are supported:
- Mostek MK48T02
-
- Mostek MK48T08
-
- Mostek MK48T18
-
- Mostek MK48T59
-
SEE ALSO
intro(4),
todr(9)
HISTORY
The
mk48txx driver first appeared in
NetBSD
1.5.
AUTHORS
The
mk48txx driver was written by
Paul
Kranenburg ⟨pk@NetBSD.org⟩.