MK48TXX(4)

💖 NAME 💖

okay bestie, welcome to MK48TXX(4) — the mk48txx page from the Kernel Interfaces Manual. This is the Mostek time-of-day clock driver, and it’s literally the clock chip’s main character era. ✨

mk48txx — Mostek time-of-day clock driver.

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✨ SYNOPSIS ✨

here’s the summoning circle, no cap:

       #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;
};

field-by-field tea, bestie:

• 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 the 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 the clock's two-digit year represent the year 1968.
• sc_flag — this flag is used to specify machine-dependent features.
• sc_nvread, sc_nvwrite (the struct fields are sc_nvrd, sc_nvwr) — 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, bestie: if the resulting date retrieved with the todr_gettime() method is earlier than 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.

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🔥 HARDWARE 🔥

The following models are supported, periodt:

• Mostek MK48T02
• Mostek MK48T08
• Mostek MK48T18
• Mostek MK48T59

🦋 SEE ALSO 🦋

• intro(4)
• todr(9)

🌈 HISTORY 🌈

The mk48txx driver first appeared in NetBSD 1.5. iconic.

👑 AUTHORS 👑

The mk48txx driver was written by Paul Kranenburg ⟨pk@NetBSD.org⟩. 💅

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mwah 💋 — source/version: Debian; date: October 1, 2006. That’s the whole page, bestie — go forth and clock. 🫶