diff options
Diffstat (limited to 'drivers/rtc/rtc-st-lpc.c')
| -rw-r--r-- | drivers/rtc/rtc-st-lpc.c | 354 |
1 files changed, 354 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-st-lpc.c b/drivers/rtc/rtc-st-lpc.c new file mode 100644 index 000000000..3f9d0acb8 --- /dev/null +++ b/drivers/rtc/rtc-st-lpc.c @@ -0,0 +1,354 @@ +/* + * rtc-st-lpc.c - ST's LPC RTC, powered by the Low Power Timer + * + * Copyright (C) 2014 STMicroelectronics Limited + * + * Author: David Paris <david.paris@st.com> for STMicroelectronics + * Lee Jones <lee.jones@linaro.org> for STMicroelectronics + * + * Based on the original driver written by Stuart Menefy. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ + +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/init.h> +#include <linux/io.h> +#include <linux/irq.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_irq.h> +#include <linux/platform_device.h> +#include <linux/rtc.h> + +#include <dt-bindings/mfd/st-lpc.h> + +/* Low Power Timer */ +#define LPC_LPT_LSB_OFF 0x400 +#define LPC_LPT_MSB_OFF 0x404 +#define LPC_LPT_START_OFF 0x408 + +/* Low Power Alarm */ +#define LPC_LPA_LSB_OFF 0x410 +#define LPC_LPA_MSB_OFF 0x414 +#define LPC_LPA_START_OFF 0x418 + +/* LPC as WDT */ +#define LPC_WDT_OFF 0x510 +#define LPC_WDT_FLAG_OFF 0x514 + +struct st_rtc { + struct rtc_device *rtc_dev; + struct rtc_wkalrm alarm; + struct resource *res; + struct clk *clk; + unsigned long clkrate; + void __iomem *ioaddr; + bool irq_enabled:1; + spinlock_t lock; + short irq; +}; + +static void st_rtc_set_hw_alarm(struct st_rtc *rtc, + unsigned long msb, unsigned long lsb) +{ + unsigned long flags; + + spin_lock_irqsave(&rtc->lock, flags); + + writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF); + + writel_relaxed(msb, rtc->ioaddr + LPC_LPA_MSB_OFF); + writel_relaxed(lsb, rtc->ioaddr + LPC_LPA_LSB_OFF); + writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF); + + writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF); + + spin_unlock_irqrestore(&rtc->lock, flags); +} + +static irqreturn_t st_rtc_handler(int this_irq, void *data) +{ + struct st_rtc *rtc = (struct st_rtc *)data; + + rtc_update_irq(rtc->rtc_dev, 1, RTC_AF); + + return IRQ_HANDLED; +} + +static int st_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct st_rtc *rtc = dev_get_drvdata(dev); + unsigned long lpt_lsb, lpt_msb; + unsigned long long lpt; + unsigned long flags; + + spin_lock_irqsave(&rtc->lock, flags); + + do { + lpt_msb = readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF); + lpt_lsb = readl_relaxed(rtc->ioaddr + LPC_LPT_LSB_OFF); + } while (readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF) != lpt_msb); + + spin_unlock_irqrestore(&rtc->lock, flags); + + lpt = ((unsigned long long)lpt_msb << 32) | lpt_lsb; + do_div(lpt, rtc->clkrate); + rtc_time_to_tm(lpt, tm); + + return 0; +} + +static int st_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct st_rtc *rtc = dev_get_drvdata(dev); + unsigned long long lpt; + unsigned long secs, flags; + int ret; + + ret = rtc_tm_to_time(tm, &secs); + if (ret) + return ret; + + lpt = (unsigned long long)secs * rtc->clkrate; + + spin_lock_irqsave(&rtc->lock, flags); + + writel_relaxed(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF); + writel_relaxed(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF); + writel_relaxed(1, rtc->ioaddr + LPC_LPT_START_OFF); + + spin_unlock_irqrestore(&rtc->lock, flags); + + return 0; +} + +static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm) +{ + struct st_rtc *rtc = dev_get_drvdata(dev); + unsigned long flags; + + spin_lock_irqsave(&rtc->lock, flags); + + memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm)); + + spin_unlock_irqrestore(&rtc->lock, flags); + + return 0; +} + +static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled) +{ + struct st_rtc *rtc = dev_get_drvdata(dev); + + if (enabled && !rtc->irq_enabled) { + enable_irq(rtc->irq); + rtc->irq_enabled = true; + } else if (!enabled && rtc->irq_enabled) { + disable_irq(rtc->irq); + rtc->irq_enabled = false; + } + + return 0; +} + +static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t) +{ + struct st_rtc *rtc = dev_get_drvdata(dev); + struct rtc_time now; + unsigned long now_secs; + unsigned long alarm_secs; + unsigned long long lpa; + + st_rtc_read_time(dev, &now); + rtc_tm_to_time(&now, &now_secs); + rtc_tm_to_time(&t->time, &alarm_secs); + + /* Invalid alarm time */ + if (now_secs > alarm_secs) + return -EINVAL; + + memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm)); + + /* Now many secs to fire */ + alarm_secs -= now_secs; + lpa = (unsigned long long)alarm_secs * rtc->clkrate; + + st_rtc_set_hw_alarm(rtc, lpa >> 32, lpa); + st_rtc_alarm_irq_enable(dev, t->enabled); + + return 0; +} + +static struct rtc_class_ops st_rtc_ops = { + .read_time = st_rtc_read_time, + .set_time = st_rtc_set_time, + .read_alarm = st_rtc_read_alarm, + .set_alarm = st_rtc_set_alarm, + .alarm_irq_enable = st_rtc_alarm_irq_enable, +}; + +static int st_rtc_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct st_rtc *rtc; + struct resource *res; + struct rtc_time tm_check; + uint32_t mode; + int ret = 0; + + ret = of_property_read_u32(np, "st,lpc-mode", &mode); + if (ret) { + dev_err(&pdev->dev, "An LPC mode must be provided\n"); + return -EINVAL; + } + + /* LPC can either run in RTC or WDT mode */ + if (mode != ST_LPC_MODE_RTC) + return -ENODEV; + + rtc = devm_kzalloc(&pdev->dev, sizeof(struct st_rtc), GFP_KERNEL); + if (!rtc) + return -ENOMEM; + + spin_lock_init(&rtc->lock); + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + rtc->ioaddr = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(rtc->ioaddr)) + return PTR_ERR(rtc->ioaddr); + + rtc->irq = irq_of_parse_and_map(np, 0); + if (!rtc->irq) { + dev_err(&pdev->dev, "IRQ missing or invalid\n"); + return -EINVAL; + } + + ret = devm_request_irq(&pdev->dev, rtc->irq, st_rtc_handler, 0, + pdev->name, rtc); + if (ret) { + dev_err(&pdev->dev, "Failed to request irq %i\n", rtc->irq); + return ret; + } + + enable_irq_wake(rtc->irq); + disable_irq(rtc->irq); + + rtc->clk = clk_get(&pdev->dev, NULL); + if (IS_ERR(rtc->clk)) { + dev_err(&pdev->dev, "Unable to request clock\n"); + return PTR_ERR(rtc->clk); + } + + clk_prepare_enable(rtc->clk); + + rtc->clkrate = clk_get_rate(rtc->clk); + if (!rtc->clkrate) { + dev_err(&pdev->dev, "Unable to fetch clock rate\n"); + return -EINVAL; + } + + device_set_wakeup_capable(&pdev->dev, 1); + + platform_set_drvdata(pdev, rtc); + + /* + * The RTC-LPC is able to manage date.year > 2038 + * but currently the kernel can not manage this date! + * If the RTC-LPC has a date.year > 2038 then + * it's set to the epoch "Jan 1st 2000" + */ + st_rtc_read_time(&pdev->dev, &tm_check); + + if (tm_check.tm_year >= (2038 - 1900)) { + memset(&tm_check, 0, sizeof(tm_check)); + tm_check.tm_year = 100; + tm_check.tm_mday = 1; + st_rtc_set_time(&pdev->dev, &tm_check); + } + + rtc->rtc_dev = rtc_device_register("st-lpc-rtc", &pdev->dev, + &st_rtc_ops, THIS_MODULE); + if (IS_ERR(rtc->rtc_dev)) { + clk_disable_unprepare(rtc->clk); + return PTR_ERR(rtc->rtc_dev); + } + + return 0; +} + +static int st_rtc_remove(struct platform_device *pdev) +{ + struct st_rtc *rtc = platform_get_drvdata(pdev); + + if (likely(rtc->rtc_dev)) + rtc_device_unregister(rtc->rtc_dev); + + return 0; +} + +#ifdef CONFIG_PM_SLEEP +static int st_rtc_suspend(struct device *dev) +{ + struct st_rtc *rtc = dev_get_drvdata(dev); + + if (device_may_wakeup(dev)) + return 0; + + writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF); + writel_relaxed(0, rtc->ioaddr + LPC_LPA_START_OFF); + writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF); + + return 0; +} + +static int st_rtc_resume(struct device *dev) +{ + struct st_rtc *rtc = dev_get_drvdata(dev); + + rtc_alarm_irq_enable(rtc->rtc_dev, 0); + + /* + * clean 'rtc->alarm' to allow a new + * .set_alarm to the upper RTC layer + */ + memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm)); + + writel_relaxed(0, rtc->ioaddr + LPC_LPA_MSB_OFF); + writel_relaxed(0, rtc->ioaddr + LPC_LPA_LSB_OFF); + writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF); + writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF); + writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF); + + return 0; +} +#endif + +static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume); + +static const struct of_device_id st_rtc_match[] = { + { .compatible = "st,stih407-lpc" }, + {} +}; +MODULE_DEVICE_TABLE(of, st_rtc_match); + +static struct platform_driver st_rtc_platform_driver = { + .driver = { + .name = "st-lpc-rtc", + .pm = &st_rtc_pm_ops, + .of_match_table = st_rtc_match, + }, + .probe = st_rtc_probe, + .remove = st_rtc_remove, +}; + +module_platform_driver(st_rtc_platform_driver); + +MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver"); +MODULE_AUTHOR("David Paris <david.paris@st.com>"); +MODULE_LICENSE("GPL"); |