// SPDX-License-Identifier: GPL-2.0+ /* * "RTT as Real Time Clock" driver for AT91SAM9 SoC family * * (C) 2007 Michel Benoit * * Based on rtc-at91rm9200.c by Rick Bronson */ #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 … #define AT91_RTT_RTPRES … #define AT91_RTT_ALMIEN … #define AT91_RTT_RTTINCIEN … #define AT91_RTT_RTTRST … #define AT91_RTT_AR … #define AT91_RTT_ALMV … #define AT91_RTT_VR … #define AT91_RTT_CRTV … #define AT91_RTT_SR … #define AT91_RTT_ALMS … #define AT91_RTT_RTTINC … /* * 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 … struct sam9_rtc { … }; #define rtt_readl(rtc, field) … #define rtt_writel(rtc, field, val) … static inline unsigned int gpbr_readl(struct sam9_rtc *rtc) { … } static inline void gpbr_writel(struct sam9_rtc *rtc, unsigned int val) { … } /* * Read current time and date in RTC */ static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm) { … } /* * Set current time and date in RTC */ static int at91_rtc_settime(struct device *dev, struct rtc_time *tm) { … } static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm) { … } static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm) { … } static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled) { … } /* * Provide additional RTC information in /proc/driver/rtc */ static int at91_rtc_proc(struct device *dev, struct seq_file *seq) { … } static irqreturn_t at91_rtc_cache_events(struct sam9_rtc *rtc) { … } static void at91_rtc_flush_events(struct sam9_rtc *rtc) { … } /* * IRQ handler for the RTC */ static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc) { … } static const struct rtc_class_ops at91_rtc_ops = …; /* * Initialize and install RTC driver */ static int at91_rtc_probe(struct platform_device *pdev) { … } /* * Disable and remove the RTC driver */ static void at91_rtc_remove(struct platform_device *pdev) { … } static void at91_rtc_shutdown(struct platform_device *pdev) { … } #ifdef CONFIG_PM_SLEEP /* AT91SAM9 RTC Power management control */ static int at91_rtc_suspend(struct device *dev) { … } static int at91_rtc_resume(struct device *dev) { … } #endif static SIMPLE_DEV_PM_OPS(at91_rtc_pm_ops, at91_rtc_suspend, at91_rtc_resume); static const struct of_device_id at91_rtc_dt_ids[] = …; MODULE_DEVICE_TABLE(of, at91_rtc_dt_ids); static struct platform_driver at91_rtc_driver = …; module_platform_driver(…) …; MODULE_AUTHOR(…) …; MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …;
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