linux-imx

/*

 * "RTT as Real Time Clock" driver for AT91SAM9 SoC family

 *

 * (C) 2007 Michel Benoit

 *

 * Based on rtc-at91rm9200.c by Rick Bronson

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version

 * 2 of the License, or (at your option) any later version.

 */

​

#include <linux/clk.h>

#include <linux/interrupt.h>

#include <linux/ioctl.h>

#include <linux/io.h>

#include <linux/kernel.h>

#include <linux/mfd/syscon.h>

#include <linux/module.h>

#include <linux/of.h>

#include <linux/platform_device.h>

#include <linux/regmap.h>

#include <linux/rtc.h>

#include <linux/slab.h>

#include <linux/suspend.h>

#include <linux/time.h>

​

/*

 * This driver uses two configurable hardware resources that live in the

 * AT91SAM9 backup power domain (intended to be powered at all times)

 * to implement the Real Time Clock interfaces

 *

 *  - A "Real-time Timer" (RTT) counts up in seconds from a base time.

 *    We can't assign the counter value (CRTV) ... but we can reset it.

 *

 *  - One of the "General Purpose Backup Registers" (GPBRs) holds the

 *    base time, normally an offset from the beginning of the POSIX

 *    epoch (1970-Jan-1 00:00:00 UTC).  Some systems also include the

 *    local timezone's offset.

 *

 * The RTC's value is the RTT counter plus that offset.  The RTC's alarm

 * is likewise a base (ALMV) plus that offset.

 *

 * Not all RTTs will be used as RTCs; some systems have multiple RTTs to

 * choose from, or a "real" RTC module.  All systems have multiple GPBR

 * registers available, likewise usable for more than "RTC" support.

 */

​

#define AT91_RTT_MR     0x00            /* Real-time Mode Register */

#define AT91_RTT_RTPRES     (0xffff << 0)       /* Real-time Timer Prescaler Value */

#define AT91_RTT_ALMIEN     (1 << 16)       /* Alarm Interrupt Enable */

#define AT91_RTT_RTTINCIEN  (1 << 17)       /* Real Time Timer Increment Interrupt Enable */

#define AT91_RTT_RTTRST     (1 << 18)       /* Real Time Timer Restart */

​

#define AT91_RTT_AR     0x04            /* Real-time Alarm Register */

#define AT91_RTT_ALMV       (0xffffffff)        /* Alarm Value */

​

#define AT91_RTT_VR     0x08            /* Real-time Value Register */

#define AT91_RTT_CRTV       (0xffffffff)        /* Current Real-time Value */

​

#define AT91_RTT_SR     0x0c            /* Real-time Status Register */

#define AT91_RTT_ALMS       (1 << 0)        /* Real-time Alarm Status */

#define AT91_RTT_RTTINC     (1 << 1)        /* Real-time Timer Increment */

​

/*

 * We store ALARM_DISABLED in ALMV to record that no alarm is set.

 * It's also the reset value for that field.

 */

#define ALARM_DISABLED  ((u32)~0)

​

​

struct sam9_rtc {

    void __iomem        *rtt;

    struct rtc_device   *rtcdev;

    u32         imr;

    struct regmap       *gpbr;

    unsigned int        gpbr_offset;

    int             irq;

    struct clk      *sclk;

    bool            suspended;

    unsigned long       events;

    spinlock_t      lock;

};

​

#define rtt_readl(rtc, field) \

    readl((rtc)->rtt + AT91_RTT_ ## field)

#define rtt_writel(rtc, field, val) \

    writel((val), (rtc)->rtt + AT91_RTT_ ## field)

​

static inline unsigned int gpbr_readl(struct sam9_rtc *rtc)

{