MFC r325233, r328956, r329170, r329172-r329173, r329224, r330403-r330407,
r330411-r330412, r330416, r330430-r330431, r330433, r330528-r330529,
r330767

r325233:
[i2c/clock] add support for EPSON RTC-8583

RTC-8583 is time-of-day clock used in some SOHO routers. This clock has
only 2 bits for year values, but thanks to user SRAM it's possible to save
year value and keep it up to date via driver code.

Tested on Planex_MZK-W300NAG (SoC is RT2880)

Submitted by: Hiroki Mori <yamori83@yahoo.co.jp>
Differential Revision: https://reviews.freebsd.org/D12833

r328956:
Use const pointers for input data not modified by clock utility functions.

r329170:
Replace the existing print_ct() private debugging function with a set of
three public functions to format and print the three major data structures
used by realtime clock drivers (clocktime, bcd_clocktime, and timespec).

r329172:
Add a set of convenience routines for RTC drivers to use for debug output,
and a debug.clock_show_io sysctl to control debugging output.

r329173:
Add a new sysctl, debug.clock_do_io, to allow manully triggering a one-shot
read or write of all registered realtime clocks. In the read case, the
values read are simply discarded. For writes, there's no alternative but
to actually write the current system time to the device.

r329224:
Fix bad indentation. Whitespace only, no functional changes.

Reported by: bde@

r330403:
Add calls to the new clock_dbgprint_xxx() functions.

r330404:
Add calls to the new clock_dbgprint_xxx() functions.

r330405:
Oops, fix a paste-o.

r330406:
Add calls to the new clock_dbgprint_xxx() functions.

r330407:
Add calls to the new clock_dbgprint_xxx() functions. Also, stop applying
a local .5 second adjustment to the time, since that is now done by the
code in subr_rtc.c.

r330411:
Convert to the new(ish) bcd_clocktime conversion functions, add calls to
the new debug output functions, and when setting the clock, propagate the
timespec nsecs to the 1/100ths register.

r330412:
Build iicbus/rtc8583 as a module.

r330416:
The year is stored in a single byte in sram, in binary format, as a count
of years since the century, so strip the century out when converting to or
from bcd_clocktime format (the conversion routines will infer century by
pivoting on 70).

r330430:
Switch to the new bcd_clocktime conversion routines, and add calls to the
new clock_dbgprint_xxx() functions.

r330431:
Switch to the new bcd_clocktime conversion routines, and add calls to the
new clock_dbgprint_xxx() functions.

r330433:
Switch to the new bcd_clocktime conversion routines, and add calls to the
new clock_dbgprint_xxx() functions.

r330528:
Fix a paste-o that broke the build. There is no softc pointer here, just
use the dev arg.

Reported by: Jonathan Looney <jonlooney@gmail.com>
Pointy hat: ian@

r330529:
Build the ds1672 driver as a module. Add a detach() to unregister the rtc.

r330767:
Convert atrtc the new style rtc debugging output. Remove the db show
command handler which provided much the same information. Removing the
possibility of accessing the hardware regs from the debugger context
paves the way for simplifying the locking code in the driver.

MFC r306288, r314936, r325527, r327971, r328005, r328039, r328068-r328069,
r328301-r328303

r306288:
Fix ds1307 probing

'compat' can never be NULL, because the compatible check loop ends when
compat->ocd_str is NULL. This causes ds1307 to attach to any unclaimed i2c
device.

r314936:
Validate values read from the RTC before trying BCD decoding

Submitted by: cem
Reported by: Michael Gmelin <freebsd@grem.de>
Tested by: Oleksandr Tymoshenko <gonzo@bluezbox.com>
Sponsored by: Dell EMC

r325527:
DS1307: Add the mcp7941x enable bit

Summary:
Existing code recognizes the mcp7941x RTC, but this RTC has an
enable bit at the same location as the "Clock Halt" bit on the ds1307, with an
opposite assertion (set == on, whereas CH set == clock stopped). Thus the
current code halts the clock, with no way to enable it.

Reviewed By: ian
Differential Revision: https://reviews.freebsd.org/D12961

r327971:
Add RTC clock conversions for BCD values, with non-panic validation.

RTC clock hardware frequently uses BCD numbers. Currently the low-level
bcd2bin() and bin2bcd() functions will KASSERT if given out-of-range BCD
values. Every RTC driver must implement its own code for validating the
unreliable data coming from the hardware to avoid a potential kernel panic.

This change introduces two new functions, clock_bcd_to_ts() and
clock_ts_to_bcd(). The former validates its inputs and returns EINVAL if any
values are out of range. The latter guarantees the returned data will be
valid BCD in a known format (4-digit years, etc).

A new bcd_clocktime structure is used with the new functions. It is similar
to the original clocktime structure, but defines the fields holding BCD
values as uint8_t (uint16_t for year), and adds a PM flag for handling hours
using AM/PM mode.

PR: 224813
Differential Revision: https://reviews.freebsd.org/D13730 (no reviewers)

r328005:
Convert the x86 RTC driver to use new validated BCD<->timespec conversions.

New common routines were added to kern/subr_clock.c for converting between
calendrical time expressed in BCD and struct timespec. The new functions
return EINVAL on error, as expected when the clock hardware does not provide
valid time.

PR: 224813
Differential Revision: https://reviews.freebsd.org/D13731 (no reviewers)

r328039:
Add static inline rtcin_locked() and rtcout_locked() functions for doing a
related series of operations without doing a lock/unlock for each byte.
Use them when reading and writing the entire set of time registers.

The original rtcin() and writertc() functions which do lock/unlock on each
byte still exist, because they are public and called by outside code.

r328068:
Move some code around and rename a couple variables; no functional changes.

The static atrtc_set() function was called only from clock_settime(), so
just move its contents entirely into clock_settime() and delete atrtc_set().

Rename the struct bcd_clocktime variables from 'ct' to 'bct'. I had
originally wanted to emphasize how identical the clocktime and bcd_clocktime
structs were, but things evolved to the point where the structs are not at
all identical anymore, so now emphasizing the difference seems better.

r328069:
Remove redundant critical_enter/exit() calls. The block of code delimited
by these calls is now protected by a spin mutex (obscured within the
RTC_LOCK/RTC_UNLOCK macros).

Reported by: bde@

r328301:
Switch to using the bcd_clocktime conversion functinos that validate the BCD
data without panicking, and have common code for handling AM/PM mode.

r328302:
Switch to using the bcd_clocktime conversion functions that validate the BCD
data without panicking, and have common code for handling AM/PM mode.

r328303:
Switch to using the bcd_clocktime conversion functions that validate the BCD
data without panicking, and have common code for handling AM/PM mode.

MFC r327756-r327758

r327756:
Bugfix: on RTC chips with a 32-bit binary counter, after reading the time,
return immediately rather than falling through to the logic that reads
BCD-encoded time.

r327757:
Bugfix: don't lose the am/pm mode flag when setting the time. Unlike most
RTC chips that have a control register bit for am/pm mode, the DS13xx series
uses one of the high bits in the hour register. Thus, when setting the time
in am/pm mode, the am/pm mode flag has to be ORed into the hour.

r327758:
Convert a collection of unrelated bitwise flags to a collection of boolean
vars in the softc. It makes the code more compact and readable, and
actually uses less memory too.

MFC r321708-r321712, r321721, r321726-r321727, r321746, r321751,
r321791-r321792, r321795, r321798, r321821, r321823, r321826,
r321828, r321841, r321934, r322025-r322026, r322282, r322431,
r322473, r322475-r322479

Lots of i2c RTC driver stuff...

r321708:
Replace the pcf8563 i2c RTC driver with a new nxprtc driver which handles
all the chips in the NXP PCA212x and PCA/PCF85xx series. In addition to
supporting more chips, this driver uses the countdown timer on the chips as
a fractional seconds counter, giving it a resolution of about 15 milliseconds.

r321709:
Fix building this driver on non-FDT platforms.

r321710:
Add a few missing i2c devices that build fine on all arches.

r321711:
Move the device descriptions onto the device lines, so they cut and paste
nicely into other config files.

r321712:
Add the i2c RTC drivers found on various arm systems.

r321721:
Switch from using iic_transfer() to iicdev_readfrom/writeto(), mostly so
that transfers will be done with proper ownership of the bus. No
behavioral changes.

r321726:
Bugfixes and enhancements...

Don't enable the oscillator when it is found to be stopped at init time,
just let the first setting of valid time start it. But still report a dead
battery if it's stopped at init time.

Don't force the chip into 24hr mode, just cope with whatever mode it is
already in.

Align the RTC clock to top of second when setting it.

r321727:
Fix AM/PM mode handling. The bits to mask off in the hours register changes
between 12/24 hour mode. Also fix conversion between 12 and 24 hour mode.
It's not as easy as adding/subtracting 12, because the clock doesn't roll
over 11->0, it rolls over 12->1; 0 isn't a valid hour in AM/PM mode.

r321746:
Use the new clock_schedule() to arrange for clock_settime() to be called
at the right time to keep the RTC hardware time in sync, instead of using
pause_sbt() to sleep until the right time.

r321751:
Remove now-unused variable.

r321791:
Switch from using iic_transfer() to iicdev_readfrom/writeto(), mostly so
that transfers will be done with proper ownership of the bus. No
behavioral changes. Also add a detach() method.

r321792:
Add a detach() method.

r321795:
Check the clock-halted flag every time the clock is read, not just once
at startup. The flag stays set until the clock is loaded with good time,
so we need to keep saying the time is invalid until that happens.

r321798:
Restore a few rather important lines of code that got fumbled in r321746.

r321821:
No need to call getnanotime() now that the waiting is done by the central
subr_rtc code, switch from CLOCKF_SETTIME_NO_TS to CLOCKF_SETTIME_NO_ADJ
so that we get fed a timestamp, but it's not adjusted to compensate for
inaccuracy in setting time.

r321823:
Bugfixes and enhancements...

Don't enable the oscillator when it is found to be stopped at init time,
just let the first setting of valid time start it. But still report a dead
battery if it's stopped at init time.

Don't force the chip into 24hr mode, just cope with whatever mode it is
already in.

Schedule the clock_settime() callbacks to align the RTC clock to top of
second when setting it.

r321826:
Restructure the SUBDIR list as 1-per-line and alphabetize, so it will be
easier to add new things (and see what changed) in the future.

r321828:
Build iicbus/{ds1307,ds3231,nxprtc} as modules.

r321841:
Add a driver for the Intersil ISL12xx family of i2c RTC chips.

Supports ISL1209, ISL1218, ISL1219, ISL1220, ISL1221 (just basic RTC
functionality, not all the other fancy stuff the chips can do).

r321934:
Add missing ofw_bus_if.h src file.

r322025:
Switch to iicdev_readfrom/writeto() to do xfers with proper bus ownership.

Tested by: manu@

r322026:
Add missing header file to SRCS.

Reported by: manu@

r322282:
Remove the ds133x and s35390a i2c RTC drivers for now. They both do i2c
transfers in their probe() or attach() routines, and that doesn't work
when the low-level controller requires interrupts to be functional.

The DS133x family of chips is nearly identical to the DS1307 and support
for them should be added to that driver, then the ds133x driver can be
deleted. The s35390a driver just needs a non-trivial workover. In both
cases that work will be done and committed separately.

r322431:
Bid for the device with BUS_PROBE_GENERIC, because this is very much a
generic driver with minimal feature support for a large number of chips.
More featureful per-chip drivers might exist (especially out-of-tree) and
those should win the bidding even if they use BUS_PROBE_DEFAULT.

r322473:
Add a new driver, ds13rtc, that handles all DS13xx series i2c RTC chips.

This driver supports only basic timekeeping functionality. It completely
replaces the ds133x driver. It can also replace the ds1374 driver, but that
will take a few other changes in MIPS code and config, and will be committed
separately. It does NOT replace the existing ds1307 driver, which provides
access to some of the extended features on the 1307 chip, such as controlling
the square wave output signal. If both ds1307 and ds13rtc drivers are
present, the ds1307 driver will outbid and win control of the device.

This driver can be configured with FDT data, or by using hints on non-FDT
systems. In addition to the standard hints for i2c devices, it requires
a "chiptype" string of the form "dallas,ds13xx" where 'xx' is the chip id
(i.e., the same format as FDT compat strings).

r322475:
Change "chiptype" to "compatible". Making the hint name the same as the FDT
property name should make it easier to document the list of names accepted
by both configuration mechanisms.

r322476:
Remove the old ds1374 driver and use the ds13rtc driver instead. Adjust
several mips config files accordingly.

r322477:
Minor fixes and enhancements for the s35390a i2c RTC driver...

- Add FDT probe code.
- Do i2c transfers with exclusive bus ownership.
- Use config_intrhook_oneshot() to defer chip setup because some i2c
busses can't do transfers without interrupts.
- Add a detach() routine.
- Add to module build.

r322478:
Add back the drivers for Dallas/Maxim ds13xx and Seiko S35390x now that
they've been rewritten/fixed to not cause panics by doing i2c transfers
before interrupts are available.

PR: 221227

r322479:
Add hinted attachment for non-FDT systems. Also, print a message if
setting up the timer fails, because on some types of chips that's the
first attempt to access the device. If the chip is missing/non-responsive
then you'd get a driver that attached and didn't register the rtc, with
no clue about why. On other chip types there are inits that come before
timer setup, and they already print messages about errors.