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MK48TXX(4)			   BSD Kernel Interfaces Manual 		       MK48TXX(4)

     mk48txx -- Mostek time-of-day clock driver

     #include <dev/ic/mk48txxreg.h>
     #include <dev/ic/mk48txxvar.h>
     define mk48txx
     file   dev/ic/mk48txx.c	mk48txx

     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_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)

	   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

	   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 gen-
			 erally 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_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,

     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.

     The following models are supported:

	   Mostek MK48T02
	   Mostek MK48T08
	   Mostek MK48T18
	   Mostek MK48T59

     intro(4), todr(9)

     The mk48txx driver first appeared in NetBSD 1.5.

     The mk48txx driver was written by Paul Kranenburg <pk@NetBSD.org>.

BSD					 October 1, 2006				      BSD
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