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Date:      Sat, 29 Jul 2017 23:45:57 +0000 (UTC)
From:      Ian Lepore <ian@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r321708 - in head/sys: conf dev/iicbus
Message-ID:  <201707292345.v6TNjvSb025615@repo.freebsd.org>

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Author: ian
Date: Sat Jul 29 23:45:57 2017
New Revision: 321708
URL: https://svnweb.freebsd.org/changeset/base/321708

Log:
  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.

Added:
  head/sys/dev/iicbus/nxprtc.c   (contents, props changed)
Deleted:
  head/sys/dev/iicbus/pcf8563.c
  head/sys/dev/iicbus/pcf8563reg.h
Modified:
  head/sys/conf/files

Modified: head/sys/conf/files
==============================================================================
--- head/sys/conf/files	Sat Jul 29 23:31:21 2017	(r321707)
+++ head/sys/conf/files	Sat Jul 29 23:45:57 2017	(r321708)
@@ -1737,8 +1737,8 @@ dev/iicbus/iicsmb.c		optional iicsmb				\
 	dependency	"iicbus_if.h"
 dev/iicbus/iicoc.c		optional iicoc
 dev/iicbus/lm75.c		optional lm75
+dev/iicbus/nxprtc.c		optional nxprtc | pcf8563
 dev/iicbus/ofw_iicbus.c		optional fdt iicbus
-dev/iicbus/pcf8563.c		optional pcf8563
 dev/iicbus/s35390a.c		optional s35390a
 dev/iir/iir.c			optional iir
 dev/iir/iir_ctrl.c		optional iir

Added: head/sys/dev/iicbus/nxprtc.c
==============================================================================
--- /dev/null	00:00:00 1970	(empty, because file is newly added)
+++ head/sys/dev/iicbus/nxprtc.c	Sat Jul 29 23:45:57 2017	(r321708)
@@ -0,0 +1,787 @@
+/*-
+ * Copyright (c) 2017 Ian Lepore <ian@freebsd.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+/*
+ * Driver for NXP real-time clock/calendar chips:
+ *  - PCF8563 = low power, countdown timer
+ *  - PCA8565 = like PCF8563, automotive temperature range
+ *  - PCF8523 = low power, countdown timer, oscillator freq tuning, 2 timers
+ *  - PCF2127 = like PCF8523, industrial, tcxo, tamper/ts, i2c & spi, 512B ram
+ *  - PCA2129 = like PCF8523, automotive, tcxo, tamper/ts, i2c & spi, no timer
+ *  - PCF2129 = like PCF8523, industrial, tcxo, tamper/ts, i2c & spi, no timer
+ *
+ *  Most chips have a countdown timer, ostensibly intended to generate periodic
+ *  interrupt signals on an output pin.  The timer is driven from the same
+ *  divider chain that clocks the time of day registers, and they start counting
+ *  in sync when the STOP bit is cleared after the time and timer registers are
+ *  set.  The timer register can also be read on the fly, so we use it to count
+ *  fractional seconds and get a resolution of ~15ms.
+ */
+
+#include "opt_platform.h"
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/bus.h>
+#include <sys/clock.h>
+#include <sys/kernel.h>
+#include <sys/libkern.h>
+#include <sys/module.h>
+
+#include <dev/iicbus/iicbus.h>
+#include <dev/iicbus/iiconf.h>
+#ifdef FDT
+#include <dev/ofw/openfirm.h>
+#include <dev/ofw/ofw_bus.h>
+#include <dev/ofw/ofw_bus_subr.h>
+#endif
+
+#include "clock_if.h"
+#include "iicbus_if.h"
+
+/*
+ * I2C address 1010 001x : PCA2129 PCF2127 PCF2129 PCF8563 PCF8565
+ * I2C address 1101 000x : PCF8523
+ */
+#define	PCF8563_ADDR		0xa2
+#define	PCF8523_ADDR		0xd0
+
+/*
+ * Registers, bits within them, and masks that are common to all chip types.
+ */
+#define	PCF85xx_R_CS1		0x00	/* CS1 and CS2 control regs are in */
+#define	PCF85xx_R_CS2		0x01	/* the same location on all chips. */
+
+#define	PCF85xx_B_CS1_STOP	0x20	/* Stop time incrementing bit */
+#define	PCF85xx_B_SECOND_OS	0x80	/* Oscillator Stopped bit */
+
+#define	PCF85xx_M_SECOND	0x7f	/* Masks for all BCD time regs... */
+#define	PCF85xx_M_MINUTE	0x7f
+#define	PCF85xx_M_HOUR		0x3f
+#define	PCF85xx_M_DAY		0x3f
+#define	PCF85xx_M_MONTH		0x1f
+#define	PCF85xx_M_YEAR		0xff
+
+/*
+ * PCF2127-specific registers, bits, and masks.
+ */
+#define	PCF2127_R_TMR_CTL	0x10	/* Timer/watchdog control */
+
+#define	PCF2127_M_TMR_CTRL	0xe3	/* Mask off undef bits */
+
+#define	PCF2127_B_TMR_CD	0x40	/* Run in countdown mode */
+#define	PCF2127_B_TMR_64HZ	0x01	/* Timer frequency 64Hz */
+
+/*
+ * PCA/PCF2129-specific registers, bits, and masks.
+ */
+#define	PCF2129_B_CS1_12HR	0x04	/* Use 12-hour (AM/PM) mode bit */
+#define	PCF2129_B_CLKOUT_OTPR	0x20	/* OTP refresh command */
+#define	PCF2129_B_CLKOUT_HIGHZ	0x07	/* Clock Out Freq = disable */
+
+/*
+ * PCF8523-specific registers, bits, and masks.
+ */
+#define	PCF8523_R_CS3		0x02	/* Control and status reg 3 */
+#define	PCF8523_R_SECOND	0x03	/* Seconds */
+#define	PCF8523_R_TMR_CLKOUT	0x0F	/* Timer and clockout control */
+#define	PCF8523_R_TMR_A_FREQ	0x10	/* Timer A frequency control */
+#define	PCF8523_R_TMR_A_COUNT	0x11	/* Timer A count */
+
+#define	PCF8523_M_TMR_A_FREQ	0x07	/* Mask off undef bits */
+
+#define	PCF8523_B_HOUR_PM	0x20	/* PM bit */
+#define	PCF8523_B_CS1_SOFTRESET	0x58	/* Initiate Soft Reset bits */
+#define	PCF8523_B_CS1_12HR	0x08	/* Use 12-hour (AM/PM) mode bit */
+#define	PCF8523_B_CLKOUT_TACD	0x02	/* TimerA runs in CountDown mode */
+#define	PCF8523_B_CLKOUT_HIGHZ	0x38	/* Clock Out Freq = disable */
+#define	PCF8523_B_TMR_A_64HZ	0x01	/* Timer A freq 64Hz */
+
+#define	PCF8523_M_CS3_PM	0xE0	/* Power mode mask */
+#define	PCF8523_B_CS3_PM_NOBAT	0xE0	/* PM bits: no battery usage */
+#define	PCF8523_B_CS3_PM_STD	0x00	/* PM bits: standard */
+#define	PCF8523_B_CS3_BLF	0x04	/* Battery Low Flag bit */
+
+/*
+ * PCF8563-specific registers, bits, and masks.
+ */
+#define	PCF8563_R_SECOND	0x02	/* Seconds */
+#define	PCF8563_R_TMR_CTRL	0x0e	/* Timer control */
+#define	PCF8563_R_TMR_COUNT	0x0f	/* Timer count */
+
+#define	PCF8563_M_TMR_CTRL	0x93	/* Mask off undef bits */
+
+#define	PCF8563_B_TMR_ENABLE	0x80	/* Enable countdown timer */
+#define	PCF8563_B_TMR_64HZ	0x01	/* Timer frequency 64Hz */
+
+#define	PCF8563_B_MONTH_C	0x80	/* Century bit */
+
+/*
+ * We use the countdown timer for fractional seconds.  We program it for 64 Hz,
+ * the fastest available rate that doesn't roll over in less than a second.
+ */
+#define	TMR_TICKS_SEC		64
+#define	TMR_TICKS_HALFSEC	32
+
+/*
+ * The chip types we support.
+ */
+enum {
+	TYPE_NONE,
+	TYPE_PCA2129,
+	TYPE_PCA8565,
+	TYPE_PCF2127,
+	TYPE_PCF2129,
+	TYPE_PCF8523,
+	TYPE_PCF8563,
+
+	TYPE_COUNT
+};
+static const char *desc_strings[] = {
+	"",
+	"NXP PCA2129 RTC",
+	"NXP PCA8565 RTC",
+	"NXP PCF2127 RTC",
+	"NXP PCF2129 RTC",
+	"NXP PCF8523 RTC",
+	"NXP PCF8563 RTC",
+};
+CTASSERT(nitems(desc_strings) == TYPE_COUNT);
+
+/*
+ * The time registers in the order they are laid out in hardware.
+ */
+struct time_regs {
+	uint8_t sec, min, hour, day, wday, month, year;
+};
+
+struct nxprtc_softc {
+	device_t	dev;
+	device_t	busdev;
+	struct intr_config_hook
+			config_hook;
+	u_int		flags;		/* SC_F_* flags */
+	u_int		chiptype;	/* Type of PCF85xx chip */
+	uint8_t		secaddr;	/* Address of seconds register */
+	uint8_t		tmcaddr;	/* Address of timer count register */
+	uint8_t		slave_addr;	/* PCF85xx slave address */
+	bool		use_timer;	/* Use timer for fractional sec */
+};
+
+#define	SC_F_CPOL	(1 << 0)	/* Century bit means 19xx */
+#define	SC_F_AMPM	(1 << 1)	/* Use PM flag in hours reg */
+
+#ifdef FDT
+static struct ofw_compat_data compat_data[] = {
+	{"nxp,pca2129",     TYPE_PCA2129},
+	{"nxp,pca8565",     TYPE_PCA8565},
+	{"nxp,pcf2127",     TYPE_PCF2127},
+	{"nxp,pcf2129",     TYPE_PCF2129},
+	{"nxp,pcf8523",     TYPE_PCF8523},
+	{"nxp,pcf8563",     TYPE_PCF8563},
+
+	/* Undocumented compat strings known to exist in the wild... */
+	{"pcf8563",         TYPE_PCF8563},
+	{"phg,pcf8563",     TYPE_PCF8563},
+	{"philips,pcf8563", TYPE_PCF8563},
+
+	{NULL,              TYPE_NONE},
+};
+#endif
+
+static int
+read_reg(struct nxprtc_softc *sc, uint8_t reg, uint8_t *val)
+{
+
+	return (iicdev_readfrom(sc->dev, reg, val, sizeof(*val), IIC_WAIT));
+}
+
+static int
+write_reg(struct nxprtc_softc *sc, uint8_t reg, uint8_t val)
+{
+
+	return (iicdev_writeto(sc->dev, reg, &val, sizeof(val), IIC_WAIT));
+}
+
+static int
+read_timeregs(struct nxprtc_softc *sc, struct time_regs *tregs, uint8_t *tmr)
+{
+	int err;
+	uint8_t sec, tmr1, tmr2;
+
+	/*
+	 * The datasheet says loop to read the same timer value twice because it
+	 * does not freeze while reading.  To that we add our own logic that
+	 * the seconds register must be the same before and after reading the
+	 * timer, ensuring the fractional part is from the same second as tregs.
+	 */
+	do {
+		if (sc->use_timer) {
+			if ((err = read_reg(sc, sc->secaddr, &sec)) != 0)
+				break;
+			if ((err = read_reg(sc, sc->tmcaddr, &tmr1)) != 0)
+				break;
+			if ((err = read_reg(sc, sc->tmcaddr, &tmr2)) != 0)
+				break;
+			if (tmr1 != tmr2)
+				continue;
+		}
+		if ((err = iicdev_readfrom(sc->dev, sc->secaddr, tregs,
+		    sizeof(*tregs), IIC_WAIT)) != 0)
+			break;
+	} while (sc->use_timer && tregs->sec != sec);
+
+	/*
+	 * If the timer value is greater than our hz rate (or is zero),
+	 * something is wrong.  Maybe some other OS used the timer differently?
+	 * Just set it to zero.  Likewise if we're not using the timer.  After
+	 * the offset calc below, the zero turns into 32, the mid-second point,
+	 * which in effect performs 4/5 rounding, which is just the right thing
+	 * to do if we don't have fine-grained time.
+	 */
+	if (!sc->use_timer || tmr1 > TMR_TICKS_SEC)
+		tmr1 = 0;
+
+	/*
+	 * Turn the downcounter into an upcounter.  The timer starts counting at
+	 * and rolls over at mid-second, so add half a second worth of ticks to
+	 * get its zero point back in sync with the tregs.sec rollover.
+	 */
+	*tmr = (TMR_TICKS_SEC - tmr1 + TMR_TICKS_HALFSEC) % TMR_TICKS_SEC;
+
+	return (err);
+}
+
+static int
+write_timeregs(struct nxprtc_softc *sc, struct time_regs *tregs)
+{
+
+	return (iicdev_writeto(sc->dev, sc->secaddr, tregs,
+	    sizeof(*tregs), IIC_WAIT));
+}
+
+static int
+pcf8523_start(struct nxprtc_softc *sc)
+{
+	int err;
+	uint8_t cs1, cs3, clkout;
+	bool is2129;
+
+	is2129 = (sc->chiptype == TYPE_PCA2129 || sc->chiptype == TYPE_PCF2129);
+
+	/* Read and sanity-check the control registers. */
+	if ((err = read_reg(sc, PCF85xx_R_CS1, &cs1)) != 0) {
+		device_printf(sc->dev, "cannot read RTC CS1 control\n");
+		return (err);
+	}
+	if ((err = read_reg(sc, PCF8523_R_CS3, &cs3)) != 0) {
+		device_printf(sc->dev, "cannot read RTC CS3 control\n");
+		return (err);
+	}
+
+	/*
+	 * Do a full init (soft-reset) if...
+	 *  - The chip is in battery-disable mode (fresh from the factory).
+	 *  - The clock-increment STOP flag is set (this is just insane).
+	 * After reset, battery disable mode has to be overridden to "standard"
+	 * mode.  Also, turn off clock output to save battery power.
+	 */
+	if ((cs3 & PCF8523_M_CS3_PM) == PCF8523_B_CS3_PM_NOBAT ||
+	    (cs1 & PCF85xx_B_CS1_STOP)) {
+		cs1 = PCF8523_B_CS1_SOFTRESET;
+		if ((err = write_reg(sc, PCF85xx_R_CS1, cs1)) != 0) {
+			device_printf(sc->dev, "cannot write CS1 control\n");
+			return (err);
+		}
+		cs3 = PCF8523_B_CS3_PM_STD;
+		if ((err = write_reg(sc, PCF8523_R_CS3, cs3)) != 0) {
+			device_printf(sc->dev, "cannot write CS3 control\n");
+			return (err);
+		}
+		/*
+		 * For 2129 series, trigger OTP refresh by forcing the OTPR bit
+		 * to zero then back to 1, then wait 100ms for the refresh, and
+		 * finally set the bit back to zero with the COF_HIGHZ write.
+		 */
+		if (is2129) {
+			clkout = PCF2129_B_CLKOUT_HIGHZ;
+			if ((err = write_reg(sc, PCF8523_R_TMR_CLKOUT,
+			    clkout)) != 0) {
+				device_printf(sc->dev,
+				    "cannot write CLKOUT control\n");
+				return (err);
+			}
+			if ((err = write_reg(sc, PCF8523_R_TMR_CLKOUT,
+			    clkout | PCF2129_B_CLKOUT_OTPR)) != 0) {
+				device_printf(sc->dev,
+				    "cannot write CLKOUT control\n");
+				return (err);
+			}
+			pause_sbt("nxpotp", mstosbt(100), mstosbt(10), 0);
+		} else
+			clkout = PCF8523_B_CLKOUT_HIGHZ;
+		if ((err = write_reg(sc, PCF8523_R_TMR_CLKOUT, clkout)) != 0) {
+			device_printf(sc->dev, "cannot write CLKOUT control\n");
+			return (err);
+		}
+		device_printf(sc->dev,
+		    "first time startup, enabled RTC battery operation\n");
+
+		/*
+		 * Sleep briefly so the battery monitor can make a measurement,
+		 * then re-read CS3 so battery-low status can be reported below.
+		 */
+		pause_sbt("nxpbat", mstosbt(100), 0, 0);
+		if ((err = read_reg(sc, PCF8523_R_CS3, &cs3)) != 0) {
+			device_printf(sc->dev, "cannot read RTC CS3 control\n");
+			return (err);
+		}
+	}
+
+	/* Let someone know if the battery is weak. */
+	if (cs3 & PCF8523_B_CS3_BLF)
+		device_printf(sc->dev, "WARNING: RTC battery is low\n");
+
+	/* Remember whether we're running in AM/PM mode. */
+	if (is2129) {
+		if (cs1 & PCF2129_B_CS1_12HR)
+			sc->flags |= SC_F_AMPM;
+	} else {
+		if (cs1 & PCF8523_B_CS1_12HR)
+			sc->flags |= SC_F_AMPM;
+	}
+
+	return (0);
+}
+
+static int
+pcf8523_start_timer(struct nxprtc_softc *sc)
+{
+	int err;
+	uint8_t clkout, stdclk, stdfreq, tmrfreq;
+
+	/*
+	 * Read the timer control and frequency regs.  If they don't have the
+	 * values we normally program into them then the timer count doesn't
+	 * contain a valid fractional second, so zero it to prevent using a bad
+	 * value.  Then program the normal timer values so that on the first
+	 * settime call we'll begin to use fractional time.
+	 */
+	if ((err = read_reg(sc, PCF8523_R_TMR_A_FREQ, &tmrfreq)) != 0)
+		return (err);
+	if ((err = read_reg(sc, PCF8523_R_TMR_CLKOUT, &clkout)) != 0)
+		return (err);
+
+	stdfreq = PCF8523_B_TMR_A_64HZ;
+	stdclk = PCF8523_B_CLKOUT_TACD | PCF8523_B_CLKOUT_HIGHZ;
+
+	if (clkout != stdclk || (tmrfreq & PCF8523_M_TMR_A_FREQ) != stdfreq) {
+		if ((err = write_reg(sc, sc->tmcaddr, 0)) != 0)
+			return (err);
+		if ((err = write_reg(sc, PCF8523_R_TMR_A_FREQ, stdfreq)) != 0)
+			return (err);
+		if ((err = write_reg(sc, PCF8523_R_TMR_CLKOUT, stdclk)) != 0)
+			return (err);
+	}
+	return (0);
+}
+
+static int
+pcf2127_start_timer(struct nxprtc_softc *sc)
+{
+	int err;
+	uint8_t stdctl, tmrctl;
+
+	/* See comment in pcf8523_start_timer().  */
+	if ((err = read_reg(sc, PCF2127_R_TMR_CTL, &tmrctl)) != 0)
+		return (err);
+
+	stdctl = PCF2127_B_TMR_CD | PCF8523_B_TMR_A_64HZ;
+
+	if ((tmrctl & PCF2127_M_TMR_CTRL) != stdctl) {
+		if ((err = write_reg(sc, sc->tmcaddr, 0)) != 0)
+			return (err);
+		if ((err = write_reg(sc, PCF2127_R_TMR_CTL, stdctl)) != 0)
+			return (err);
+	}
+	return (0);
+}
+
+static int
+pcf8563_start_timer(struct nxprtc_softc *sc)
+{
+	int err;
+	uint8_t stdctl, tmrctl;
+
+	/* See comment in pcf8523_start_timer().  */
+	if ((err = read_reg(sc, PCF8563_R_TMR_CTRL, &tmrctl)) != 0)
+		return (err);
+
+	stdctl = PCF8563_B_TMR_ENABLE | PCF8563_B_TMR_64HZ;
+
+	if ((tmrctl & PCF8563_M_TMR_CTRL) != stdctl) {
+		if ((err = write_reg(sc, sc->tmcaddr, 0)) != 0)
+			return (err);
+		if ((err = write_reg(sc, PCF8563_R_TMR_CTRL, stdctl)) != 0)
+			return (err);
+	}
+	return (0);
+}
+
+static void
+nxprtc_start(void *dev)
+{
+	struct nxprtc_softc *sc;
+	int clockflags, resolution;
+	uint8_t sec;
+
+	sc = device_get_softc((device_t)dev);
+	config_intrhook_disestablish(&sc->config_hook);
+
+	/* First do chip-specific inits. */
+	switch (sc->chiptype) {
+	case TYPE_PCA2129:
+	case TYPE_PCF2129:
+		if (pcf8523_start(sc) != 0)
+			return;
+		/* No timer to start */
+		break;
+	case TYPE_PCF2127:
+		if (pcf8523_start(sc) != 0)
+			return;
+		if (pcf2127_start_timer(sc) != 0)
+			return;
+		break;
+	case TYPE_PCF8523:
+		if (pcf8523_start(sc) != 0)
+			return;
+		if (pcf8523_start_timer(sc) != 0)
+			return;
+		break;
+	case TYPE_PCA8565:
+	case TYPE_PCF8563:
+		if (pcf8563_start_timer(sc) != 0)
+			return;
+		break;
+	default:
+		device_printf(sc->dev, "missing init code for this chiptype\n");
+		return;
+	}
+
+	/*
+	 * Common init.  Read the seconds register so we can check the
+	 * oscillator-stopped status bit in it.
+	 */
+	if (read_reg(sc, sc->secaddr, &sec) != 0) {
+		device_printf(sc->dev, "cannot read RTC seconds\n");
+		return;
+	}
+	if ((sec & PCF85xx_B_SECOND_OS) != 0) {
+		device_printf(sc->dev, 
+		    "WARNING: RTC battery failed; time is invalid\n");
+	}
+
+	/*
+	 * Everything looks good if we make it to here; register as an RTC.  If
+	 * we're using the timer to count fractional seconds, our resolution is
+	 * 1e6/64, about 15.6ms.  Without the timer we still align the RTC clock
+	 * when setting it so our error is an average .5s when reading it.
+	 */
+	resolution = sc->use_timer ? 1000000 / TMR_TICKS_SEC : 1000000 / 2;
+	clockflags = CLOCKF_GETTIME_NO_ADJ | CLOCKF_SETTIME_NO_TS;
+	clock_register_flags(sc->dev, resolution, clockflags);
+}
+
+static int
+nxprtc_gettime(device_t dev, struct timespec *ts)
+{
+	struct clocktime ct;
+	struct time_regs tregs;
+	struct nxprtc_softc *sc;
+	int err;
+	uint8_t cs1, tmrcount;
+
+	sc = device_get_softc(dev);
+
+	/*
+	 * Read the time, but before using it, validate that the oscillator-
+	 * stopped/power-fail bit is not set, and that the time-increment STOP
+	 * bit is not set in the control reg.  The latter can happen if there
+	 * was an error when setting the time.
+	 */
+	if ((err = read_timeregs(sc, &tregs, &tmrcount)) != 0) {
+		device_printf(dev, "cannot read RTC time\n");
+		return (err);
+	}
+	if ((err = read_reg(sc, PCF85xx_R_CS1, &cs1)) != 0) {
+		device_printf(dev, "cannot read RTC time\n");
+		return (err);
+	}
+	if ((tregs.sec & PCF85xx_B_SECOND_OS) || (cs1 & PCF85xx_B_CS1_STOP)) {
+		device_printf(dev, "RTC clock not running\n");
+		return (EINVAL); /* hardware is good, time is not. */
+	}
+
+	ct.nsec = ((uint64_t)tmrcount * 1000000000) / TMR_TICKS_SEC;
+	ct.sec  = FROMBCD(tregs.sec   & PCF85xx_M_SECOND);
+	ct.min  = FROMBCD(tregs.min   & PCF85xx_M_MINUTE);
+	ct.hour = FROMBCD(tregs.hour  & PCF85xx_M_HOUR);
+	ct.day  = FROMBCD(tregs.day   & PCF85xx_M_DAY);
+	ct.mon  = FROMBCD(tregs.month & PCF85xx_M_MONTH);
+	ct.year = FROMBCD(tregs.year  & PCF85xx_M_YEAR);
+	ct.year += 1900;
+	if (ct.year < POSIX_BASE_YEAR)
+		ct.year += 100;	/* assume [1970, 2069] */
+
+	/*
+	 * Old PCF8563 datasheets recommended that the C bit be 1 for 19xx and 0
+	 * for 20xx; newer datasheets don't recommend that.  We don't care,
+	 * but we may co-exist with other OSes sharing the hardware. Determine
+	 * existing polarity on a read so that we can preserve it on a write.
+	 */
+	if (sc->chiptype == TYPE_PCF8563) {
+		if (tregs.month & PCF8563_B_MONTH_C) {
+			if (ct.year >= 2000)
+				sc->flags |= SC_F_CPOL;
+		} else if (ct.year < 2000)
+				sc->flags |= SC_F_CPOL;
+	}
+
+	/* If this chip is running in 12-hour/AMPM mode, deal with it. */
+	if ((sc->flags & SC_F_AMPM) && (tregs.hour & PCF8523_B_HOUR_PM))
+		ct.hour += 12;
+
+	err = clock_ct_to_ts(&ct, ts);
+	ts->tv_sec += utc_offset();
+
+	return (err);
+}
+
+static int
+nxprtc_settime(device_t dev, struct timespec *ts)
+{
+	struct clocktime ct;
+	struct time_regs tregs;
+	struct nxprtc_softc *sc;
+	long waitns;
+	int err;
+	uint8_t cflag, cs1, pmflag;
+
+	sc = device_get_softc(dev);
+
+	/*
+	 * We stop the clock, set the time, then restart the clock.  Half a
+	 * second after restarting the clock it ticks over to the next second.
+	 * So to align the RTC, sleep until system time is halfway through the
+	 * current second (shoot for .495 to allow time for i2c operations).
+	 */
+	getnanotime(ts);
+	waitns = 495000000 - ts->tv_nsec;
+	if (waitns < 0)
+		waitns += 1000000000;
+	pause_sbt("nxpset", nstosbt(waitns), 0, C_PREL(31));
+
+	/*
+	 * Reserve use of the i2c bus and stop the RTC clock.  Note that if
+	 * anything goes wrong from this point on, we leave the clock stopped,
+	 * because we don't really know what state it's in.
+	 */
+	if ((err = iicbus_request_bus(sc->busdev, sc->dev, IIC_WAIT)) != 0)
+		return (err);
+	if ((err = read_reg(sc, PCF85xx_R_CS1, &cs1)) != 0)
+		goto errout;
+	cs1 |= PCF85xx_B_CS1_STOP;
+	if ((err = write_reg(sc, PCF85xx_R_CS1, cs1)) != 0)
+		goto errout;
+
+	/* Grab a fresh post-sleep idea of what time it is. */
+	getnanotime(ts);
+	ts->tv_sec -= utc_offset();
+	ts->tv_nsec = 0;
+	clock_ts_to_ct(ts, &ct);
+
+	/* If the chip is in AMPM mode deal with the PM flag. */
+	pmflag = 0;
+	if ((sc->flags & SC_F_AMPM) && ct.hour > 12) {
+		ct.hour -= 12;
+		pmflag = PCF8523_B_HOUR_PM;
+	}
+
+	/* On 8563 set the century based on the polarity seen when reading. */
+	cflag = 0;
+	if (sc->chiptype == TYPE_PCF8563) {
+		if ((sc->flags & SC_F_CPOL) != 0) {
+			if (ct.year >= 2000)
+				cflag = PCF8563_B_MONTH_C;
+		} else if (ct.year < 2000)
+				cflag = PCF8563_B_MONTH_C;
+	}
+
+	tregs.sec   = TOBCD(ct.sec);
+	tregs.min   = TOBCD(ct.min);
+	tregs.hour  = TOBCD(ct.hour) | pmflag;
+	tregs.day   = TOBCD(ct.day);
+	tregs.month = TOBCD(ct.mon);
+	tregs.year  = TOBCD(ct.year % 100) | cflag;
+	tregs.wday  = ct.dow;
+
+	/*
+	 * Set the time, reset the timer count register, then start the clocks.
+	 */
+	if ((err = write_timeregs(sc, &tregs)) != 0)
+		goto errout;
+
+	if ((err = write_reg(sc, sc->tmcaddr, TMR_TICKS_SEC)) != 0)
+		return (err);
+
+	cs1 &= ~PCF85xx_B_CS1_STOP;
+	err = write_reg(sc, PCF85xx_R_CS1, cs1);
+
+errout:
+
+	iicbus_release_bus(sc->busdev, sc->dev);
+
+	if (err != 0)
+		device_printf(dev, "cannot write RTC time\n");
+
+	return (err);
+}
+
+static int
+nxprtc_probe(device_t dev)
+{
+	int chiptype;
+
+#ifdef FDT
+	if (!ofw_bus_status_okay(dev))
+		return (ENXIO);
+
+	chiptype = ofw_bus_search_compatible(dev, compat_data)->ocd_data;
+	if (chiptype == TYPE_NONE)
+		return (ENXIO);
+#else
+	/* Historically the non-FDT driver supports only PCF8563. */
+	chiptype = TYPE_PCF8563;
+#endif
+	device_set_desc(dev, desc_strings[chiptype]);
+
+	return (BUS_PROBE_DEFAULT);
+}
+
+static int
+nxprtc_attach(device_t dev)
+{
+	struct nxprtc_softc *sc;
+
+	sc = device_get_softc(dev);
+	sc->dev = dev;
+	sc->busdev = device_get_parent(dev);
+	sc->slave_addr = iicbus_get_addr(dev);
+
+	/*
+	 * We need to know what kind of chip we're driving.  Historically the
+	 * non-FDT driver supported only PCF8563.  There is no machine-readable
+	 * identifier in the chip so we would need a set of hints defined to use
+	 * the other chips on non-FDT systems.
+	 */
+#ifdef FDT
+	sc->chiptype = ofw_bus_search_compatible(dev, compat_data)->ocd_data;
+#else
+	sc->chiptype = TYPE_PCF8563;
+	if (sc->slave_addr == 0)
+		sc->slave_addr = PCF8563_ADDR;
+#endif
+
+	/* The features and some register addresses vary by chip type. */
+	switch (sc->chiptype) {
+	case TYPE_PCA2129:
+	case TYPE_PCF2129:
+		sc->secaddr = PCF8523_R_SECOND;
+		sc->tmcaddr = 0;
+		sc->use_timer = false;
+		break;
+	case TYPE_PCF2127:
+	case TYPE_PCF8523:
+		sc->secaddr = PCF8523_R_SECOND;
+		sc->tmcaddr = PCF8523_R_TMR_A_COUNT;
+		sc->use_timer = true;
+		break;
+	case TYPE_PCA8565:
+	case TYPE_PCF8563:
+		sc->secaddr = PCF8563_R_SECOND;
+		sc->tmcaddr = PCF8563_R_TMR_COUNT;
+		sc->use_timer = true;
+		break;
+	default:
+		device_printf(dev, "impossible: cannot determine chip type\n");
+		return (ENXIO);
+	}
+
+	/*
+	 * We have to wait until interrupts are enabled.  Sometimes I2C read
+	 * and write only works when the interrupts are available.
+	 */
+	sc->config_hook.ich_func = nxprtc_start;
+	sc->config_hook.ich_arg = dev;
+	if (config_intrhook_establish(&sc->config_hook) != 0)
+		return (ENOMEM);
+
+	return (0);
+}
+
+static int
+nxprtc_detach(device_t dev)
+{
+
+	clock_unregister(dev);
+	return (0);
+}
+
+static device_method_t nxprtc_methods[] = {
+	DEVMETHOD(device_probe,		nxprtc_probe),
+	DEVMETHOD(device_attach,	nxprtc_attach),
+	DEVMETHOD(device_detach,	nxprtc_detach),
+
+	DEVMETHOD(clock_gettime,	nxprtc_gettime),
+	DEVMETHOD(clock_settime,	nxprtc_settime),
+
+	DEVMETHOD_END
+};
+
+static driver_t nxprtc_driver = {
+	"nxprtc",
+	nxprtc_methods,
+	sizeof(struct nxprtc_softc),
+};
+
+static devclass_t nxprtc_devclass;
+
+DRIVER_MODULE(nxprtc, iicbus, nxprtc_driver, nxprtc_devclass, NULL, NULL);
+MODULE_VERSION(nxprtc, 1);
+MODULE_DEPEND(nxprtc, iicbus, IICBB_MINVER, IICBB_PREFVER, IICBB_MAXVER);



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