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Release 4.11 drivers/rtc/rtc-at91sam9.c

Directory: drivers/rtc
/*
 * "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) { unsigned int val; regmap_read(rtc->gpbr, rtc->gpbr_offset, &val); return val; }

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static inline void gpbr_writel(struct sam9_rtc *rtc, unsigned int val) { regmap_write(rtc->gpbr, rtc->gpbr_offset, val); }

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/* * Read current time and date in RTC */
static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm) { struct sam9_rtc *rtc = dev_get_drvdata(dev); u32 secs, secs2; u32 offset; /* read current time offset */ offset = gpbr_readl(rtc); if (offset == 0) return -EILSEQ; /* reread the counter to help sync the two clock domains */ secs = rtt_readl(rtc, VR); secs2 = rtt_readl(rtc, VR); if (secs != secs2) secs = rtt_readl(rtc, VR); rtc_time_to_tm(offset + secs, tm); dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readtime", 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec); return 0; }

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/* * Set current time and date in RTC */
static int at91_rtc_settime(struct device *dev, struct rtc_time *tm) { struct sam9_rtc *rtc = dev_get_drvdata(dev); int err; u32 offset, alarm, mr; unsigned long secs; dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "settime", 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec); err = rtc_tm_to_time(tm, &secs); if (err != 0) return err; mr = rtt_readl(rtc, MR); /* disable interrupts */ rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN)); /* read current time offset */ offset = gpbr_readl(rtc); /* store the new base time in a battery backup register */ secs += 1; gpbr_writel(rtc, secs); /* adjust the alarm time for the new base */ alarm = rtt_readl(rtc, AR); if (alarm != ALARM_DISABLED) { if (offset > secs) { /* time jumped backwards, increase time until alarm */ alarm += (offset - secs); } else if ((alarm + offset) > secs) { /* time jumped forwards, decrease time until alarm */ alarm -= (secs - offset); } else { /* time jumped past the alarm, disable alarm */ alarm = ALARM_DISABLED; mr &= ~AT91_RTT_ALMIEN; } rtt_writel(rtc, AR, alarm); } /* reset the timer, and re-enable interrupts */ rtt_writel(rtc, MR, mr | AT91_RTT_RTTRST); return 0; }

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static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm) { struct sam9_rtc *rtc = dev_get_drvdata(dev); struct rtc_time *tm = &alrm->time; u32 alarm = rtt_readl(rtc, AR); u32 offset; offset = gpbr_readl(rtc); if (offset == 0) return -EILSEQ; memset(alrm, 0, sizeof(*alrm)); if (alarm != ALARM_DISABLED && offset != 0) { rtc_time_to_tm(offset + alarm, tm); dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readalarm", 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec); if (rtt_readl(rtc, MR) & AT91_RTT_ALMIEN) alrm->enabled = 1; } return 0; }

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static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm) { struct sam9_rtc *rtc = dev_get_drvdata(dev); struct rtc_time *tm = &alrm->time; unsigned long secs; u32 offset; u32 mr; int err; err = rtc_tm_to_time(tm, &secs); if (err != 0) return err; offset = gpbr_readl(rtc); if (offset == 0) { /* time is not set */ return -EILSEQ; } mr = rtt_readl(rtc, MR); rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN); /* alarm in the past? finish and leave disabled */ if (secs <= offset) { rtt_writel(rtc, AR, ALARM_DISABLED); return 0; } /* else set alarm and maybe enable it */ rtt_writel(rtc, AR, secs - offset); if (alrm->enabled) rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN); dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "setalarm", tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec); return 0; }

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static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled) { struct sam9_rtc *rtc = dev_get_drvdata(dev); u32 mr = rtt_readl(rtc, MR); dev_dbg(dev, "alarm_irq_enable: enabled=%08x, mr %08x\n", enabled, mr); if (enabled) rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN); else rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN); return 0; }

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/* * Provide additional RTC information in /proc/driver/rtc */
static int at91_rtc_proc(struct device *dev, struct seq_file *seq) { struct sam9_rtc *rtc = dev_get_drvdata(dev); u32 mr = rtt_readl(rtc, MR); seq_printf(seq, "update_IRQ\t: %s\n", (mr & AT91_RTT_RTTINCIEN) ? "yes" : "no"); return 0; }

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static irqreturn_t at91_rtc_cache_events(struct sam9_rtc *rtc) { u32 sr, mr; /* Shared interrupt may be for another device. Note: reading * SR clears it, so we must only read it in this irq handler! */ mr = rtt_readl(rtc, MR) & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); sr = rtt_readl(rtc, SR) & (mr >> 16); if (!sr) return IRQ_NONE; /* alarm status */ if (sr & AT91_RTT_ALMS) rtc->events |= (RTC_AF | RTC_IRQF); /* timer update/increment */ if (sr & AT91_RTT_RTTINC) rtc->events |= (RTC_UF | RTC_IRQF); return IRQ_HANDLED; }

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static void at91_rtc_flush_events(struct sam9_rtc *rtc) { if (!rtc->events) return; rtc_update_irq(rtc->rtcdev, 1, rtc->events); rtc->events = 0; pr_debug("%s: num=%ld, events=0x%02lx\n", __func__, rtc->events >> 8, rtc->events & 0x000000FF); }

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/* * IRQ handler for the RTC */
static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc) { struct sam9_rtc *rtc = _rtc; int ret; spin_lock(&rtc->lock); ret = at91_rtc_cache_events(rtc); /* We're called in suspended state */ if (rtc->suspended) { /* Mask irqs coming from this peripheral */ rtt_writel(rtc, MR, rtt_readl(rtc, MR) & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN)); /* Trigger a system wakeup */ pm_system_wakeup(); } else { at91_rtc_flush_events(rtc); } spin_unlock(&rtc->lock); return ret; }

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static const struct rtc_class_ops at91_rtc_ops = { .read_time = at91_rtc_readtime, .set_time = at91_rtc_settime, .read_alarm = at91_rtc_readalarm, .set_alarm = at91_rtc_setalarm, .proc = at91_rtc_proc, .alarm_irq_enable = at91_rtc_alarm_irq_enable, }; static const struct regmap_config gpbr_regmap_config = { .reg_bits = 32, .val_bits = 32, .reg_stride = 4, }; /* * Initialize and install RTC driver */
static int at91_rtc_probe(struct platform_device *pdev) { struct resource *r; struct sam9_rtc *rtc; int ret, irq; u32 mr; unsigned int sclk_rate; irq = platform_get_irq(pdev, 0); if (irq < 0) { dev_err(&pdev->dev, "failed to get interrupt resource\n"); return irq; } rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL); if (!rtc) return -ENOMEM; spin_lock_init(&rtc->lock); rtc->irq = irq; /* platform setup code should have handled this; sigh */ if (!device_can_wakeup(&pdev->dev)) device_init_wakeup(&pdev->dev, 1); platform_set_drvdata(pdev, rtc); r = platform_get_resource(pdev, IORESOURCE_MEM, 0); rtc->rtt = devm_ioremap_resource(&pdev->dev, r); if (IS_ERR(rtc->rtt)) return PTR_ERR(rtc->rtt); if (!pdev->dev.of_node) { /* * TODO: Remove this code chunk when removing non DT board * support. Remember to remove the gpbr_regmap_config * variable too. */ void __iomem *gpbr; r = platform_get_resource(pdev, IORESOURCE_MEM, 1); gpbr = devm_ioremap_resource(&pdev->dev, r); if (IS_ERR(gpbr)) return PTR_ERR(gpbr); rtc->gpbr = regmap_init_mmio(NULL, gpbr, &gpbr_regmap_config); } else { struct of_phandle_args args; ret = of_parse_phandle_with_fixed_args(pdev->dev.of_node, "atmel,rtt-rtc-time-reg", 1, 0, &args); if (ret) return ret; rtc->gpbr = syscon_node_to_regmap(args.np); rtc->gpbr_offset = args.args[0]; } if (IS_ERR(rtc->gpbr)) { dev_err(&pdev->dev, "failed to retrieve gpbr regmap, aborting.\n"); return -ENOMEM; } rtc->sclk = devm_clk_get(&pdev->dev, NULL); if (IS_ERR(rtc->sclk)) return PTR_ERR(rtc->sclk); ret = clk_prepare_enable(rtc->sclk); if (ret) { dev_err(&pdev->dev, "Could not enable slow clock\n"); return ret; } sclk_rate = clk_get_rate(rtc->sclk); if (!sclk_rate || sclk_rate > AT91_RTT_RTPRES) { dev_err(&pdev->dev, "Invalid slow clock rate\n"); ret = -EINVAL; goto err_clk; } mr = rtt_readl(rtc, MR); /* unless RTT is counting at 1 Hz, re-initialize it */ if ((mr & AT91_RTT_RTPRES) != sclk_rate) { mr = AT91_RTT_RTTRST | (sclk_rate & AT91_RTT_RTPRES); gpbr_writel(rtc, 0); } /* disable all interrupts (same as on shutdown path) */ mr &= ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); rtt_writel(rtc, MR, mr); rtc->rtcdev = devm_rtc_device_register(&pdev->dev, pdev->name, &at91_rtc_ops, THIS_MODULE); if (IS_ERR(rtc->rtcdev)) { ret = PTR_ERR(rtc->rtcdev); goto err_clk; } /* register irq handler after we know what name we'll use */ ret = devm_request_irq(&pdev->dev, rtc->irq, at91_rtc_interrupt, IRQF_SHARED | IRQF_COND_SUSPEND, dev_name(&rtc->rtcdev->dev), rtc); if (ret) { dev_dbg(&pdev->dev, "can't share IRQ %d?\n", rtc->irq); goto err_clk; } /* NOTE: sam9260 rev A silicon has a ROM bug which resets the * RTT on at least some reboots. If you have that chip, you must * initialize the time from some external source like a GPS, wall * clock, discrete RTC, etc */ if (gpbr_readl(rtc) == 0) dev_warn(&pdev->dev, "%s: SET TIME!\n", dev_name(&rtc->rtcdev->dev)); return 0; err_clk: clk_disable_unprepare(rtc->sclk); return ret; }

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Jingoo Han304.82%213.33%
Jean-Christophe Plagniol-Villard243.85%213.33%
Kay Sievers81.28%16.67%
Wei Yongjun81.28%16.67%
Total623100.00%15100.00%

/* * Disable and remove the RTC driver */
static int at91_rtc_remove(struct platform_device *pdev) { struct sam9_rtc *rtc = platform_get_drvdata(pdev); u32 mr = rtt_readl(rtc, MR); /* disable all interrupts */ rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN)); clk_disable_unprepare(rtc->sclk); return 0; }

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static void at91_rtc_shutdown(struct platform_device *pdev) { struct sam9_rtc *rtc = platform_get_drvdata(pdev); u32 mr = rtt_readl(rtc, MR); rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); rtt_writel(rtc, MR, mr & ~rtc->imr); }

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#ifdef CONFIG_PM_SLEEP /* AT91SAM9 RTC Power management control */
static int at91_rtc_suspend(struct device *dev) { struct sam9_rtc *rtc = dev_get_drvdata(dev); u32 mr = rtt_readl(rtc, MR); /* * This IRQ is shared with DBGU and other hardware which isn't * necessarily a wakeup event source. */ rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); if (rtc->imr) { if (device_may_wakeup(dev) && (mr & AT91_RTT_ALMIEN)) { unsigned long flags; enable_irq_wake(rtc->irq); spin_lock_irqsave(&rtc->lock, flags); rtc->suspended = true; spin_unlock_irqrestore(&rtc->lock, flags); /* don't let RTTINC cause wakeups */ if (mr & AT91_RTT_RTTINCIEN) rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN); } else rtt_writel(rtc, MR, mr & ~rtc->imr); } return 0; }

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Total141100.00%4100.00%


static int at91_rtc_resume(struct device *dev) { struct sam9_rtc *rtc = dev_get_drvdata(dev); u32 mr; if (rtc->imr) { unsigned long flags; if (device_may_wakeup(dev)) disable_irq_wake(rtc->irq); mr = rtt_readl(rtc, MR); rtt_writel(rtc, MR, mr | rtc->imr); spin_lock_irqsave(&rtc->lock, flags); rtc->suspended = false; at91_rtc_cache_events(rtc); at91_rtc_flush_events(rtc); spin_unlock_irqrestore(&rtc->lock, flags); } return 0; }

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Ludovic Desroches32.70%125.00%
Total111100.00%4100.00%

#endif static SIMPLE_DEV_PM_OPS(at91_rtc_pm_ops, at91_rtc_suspend, at91_rtc_resume); #ifdef CONFIG_OF static const struct of_device_id at91_rtc_dt_ids[] = { { .compatible = "atmel,at91sam9260-rtt" }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, at91_rtc_dt_ids); #endif static struct platform_driver at91_rtc_driver = { .probe = at91_rtc_probe, .remove = at91_rtc_remove, .shutdown = at91_rtc_shutdown, .driver = { .name = "rtc-at91sam9", .pm = &at91_rtc_pm_ops, .of_match_table = of_match_ptr(at91_rtc_dt_ids), }, }; module_platform_driver(at91_rtc_driver); MODULE_AUTHOR("Michel Benoit"); MODULE_DESCRIPTION("RTC driver for Atmel AT91SAM9x"); MODULE_LICENSE("GPL");

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John Stultz592.36%13.57%
Alexandre Belloni592.36%414.29%
Jingoo Han532.12%310.71%
Ludovic Desroches532.12%13.57%
Jean-Christophe Plagniol-Villard371.48%310.71%
Wei Yongjun80.32%13.57%
Kay Sievers80.32%13.57%
Jelle Martijn Kok10.04%13.57%
Julia Lawall10.04%13.57%
Harvey Harrison10.04%13.57%
Devendra Naga10.04%13.57%
Krzysztof Kozlowski10.04%13.57%
Total2501100.00%28100.00%
Directory: drivers/rtc
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