ST's Low Power Controller (LPC) controls two devices; watchdog and RTC. Only one of the devices can be used at any one time. This is enforced by the correlating MFD driver. This portion of the driver-set controls the Real Time Clock. Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Lee Jones <lee.jones@linaro.org>tirimbino
Lee Jones
10 years ago
parent
5cb69745da
commit
b5b2bdfc28
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/*
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* rtc-st-lpc.c - ST's LPC RTC, powered by the Low Power Timer |
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* |
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* Copyright (C) 2014 STMicroelectronics Limited |
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* |
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* Author: David Paris <david.paris@st.com> for STMicroelectronics |
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* Lee Jones <lee.jones@linaro.org> for STMicroelectronics |
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* |
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* Based on the original driver written by Stuart Menefy. |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU General Public Licence |
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* as published by the Free Software Foundation; either version |
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* 2 of the Licence, or (at your option) any later version. |
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*/ |
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#include <linux/clk.h> |
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#include <linux/delay.h> |
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#include <linux/init.h> |
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#include <linux/io.h> |
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#include <linux/irq.h> |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <linux/of.h> |
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#include <linux/of_irq.h> |
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#include <linux/platform_device.h> |
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#include <linux/rtc.h> |
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#include <dt-bindings/mfd/st-lpc.h> |
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/* Low Power Timer */ |
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#define LPC_LPT_LSB_OFF 0x400 |
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#define LPC_LPT_MSB_OFF 0x404 |
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#define LPC_LPT_START_OFF 0x408 |
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/* Low Power Alarm */ |
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#define LPC_LPA_LSB_OFF 0x410 |
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#define LPC_LPA_MSB_OFF 0x414 |
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#define LPC_LPA_START_OFF 0x418 |
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/* LPC as WDT */ |
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#define LPC_WDT_OFF 0x510 |
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#define LPC_WDT_FLAG_OFF 0x514 |
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struct st_rtc { |
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struct rtc_device *rtc_dev; |
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struct rtc_wkalrm alarm; |
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struct resource *res; |
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struct clk *clk; |
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unsigned long clkrate; |
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void __iomem *ioaddr; |
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bool irq_enabled:1; |
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spinlock_t lock; |
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short irq; |
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}; |
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static void st_rtc_set_hw_alarm(struct st_rtc *rtc, |
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unsigned long msb, unsigned long lsb) |
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{ |
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unsigned long flags; |
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spin_lock_irqsave(&rtc->lock, flags); |
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writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF); |
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writel_relaxed(msb, rtc->ioaddr + LPC_LPA_MSB_OFF); |
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writel_relaxed(lsb, rtc->ioaddr + LPC_LPA_LSB_OFF); |
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writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF); |
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writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF); |
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spin_unlock_irqrestore(&rtc->lock, flags); |
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} |
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static irqreturn_t st_rtc_handler(int this_irq, void *data) |
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{ |
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struct st_rtc *rtc = (struct st_rtc *)data; |
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rtc_update_irq(rtc->rtc_dev, 1, RTC_AF); |
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return IRQ_HANDLED; |
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} |
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static int st_rtc_read_time(struct device *dev, struct rtc_time *tm) |
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{ |
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struct st_rtc *rtc = dev_get_drvdata(dev); |
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unsigned long lpt_lsb, lpt_msb; |
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unsigned long long lpt; |
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unsigned long flags; |
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spin_lock_irqsave(&rtc->lock, flags); |
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do { |
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lpt_msb = readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF); |
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lpt_lsb = readl_relaxed(rtc->ioaddr + LPC_LPT_LSB_OFF); |
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} while (readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF) != lpt_msb); |
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spin_unlock_irqrestore(&rtc->lock, flags); |
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lpt = ((unsigned long long)lpt_msb << 32) | lpt_lsb; |
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do_div(lpt, rtc->clkrate); |
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rtc_time_to_tm(lpt, tm); |
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return 0; |
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} |
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static int st_rtc_set_time(struct device *dev, struct rtc_time *tm) |
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{ |
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struct st_rtc *rtc = dev_get_drvdata(dev); |
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unsigned long long lpt; |
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unsigned long secs, flags; |
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int ret; |
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ret = rtc_tm_to_time(tm, &secs); |
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if (ret) |
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return ret; |
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lpt = (unsigned long long)secs * rtc->clkrate; |
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spin_lock_irqsave(&rtc->lock, flags); |
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writel_relaxed(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF); |
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writel_relaxed(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF); |
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writel_relaxed(1, rtc->ioaddr + LPC_LPT_START_OFF); |
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spin_unlock_irqrestore(&rtc->lock, flags); |
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return 0; |
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} |
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static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm) |
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{ |
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struct st_rtc *rtc = dev_get_drvdata(dev); |
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unsigned long flags; |
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spin_lock_irqsave(&rtc->lock, flags); |
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memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm)); |
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spin_unlock_irqrestore(&rtc->lock, flags); |
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return 0; |
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} |
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static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled) |
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{ |
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struct st_rtc *rtc = dev_get_drvdata(dev); |
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if (enabled && !rtc->irq_enabled) { |
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enable_irq(rtc->irq); |
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rtc->irq_enabled = true; |
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} else if (!enabled && rtc->irq_enabled) { |
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disable_irq(rtc->irq); |
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rtc->irq_enabled = false; |
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} |
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return 0; |
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} |
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static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t) |
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{ |
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struct st_rtc *rtc = dev_get_drvdata(dev); |
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struct rtc_time now; |
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unsigned long now_secs; |
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unsigned long alarm_secs; |
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unsigned long long lpa; |
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st_rtc_read_time(dev, &now); |
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rtc_tm_to_time(&now, &now_secs); |
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rtc_tm_to_time(&t->time, &alarm_secs); |
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/* Invalid alarm time */ |
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if (now_secs > alarm_secs) |
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return -EINVAL; |
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memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm)); |
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/* Now many secs to fire */ |
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alarm_secs -= now_secs; |
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lpa = (unsigned long long)alarm_secs * rtc->clkrate; |
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st_rtc_set_hw_alarm(rtc, lpa >> 32, lpa); |
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st_rtc_alarm_irq_enable(dev, t->enabled); |
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return 0; |
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} |
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static struct rtc_class_ops st_rtc_ops = { |
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.read_time = st_rtc_read_time, |
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.set_time = st_rtc_set_time, |
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.read_alarm = st_rtc_read_alarm, |
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.set_alarm = st_rtc_set_alarm, |
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.alarm_irq_enable = st_rtc_alarm_irq_enable, |
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}; |
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static int st_rtc_probe(struct platform_device *pdev) |
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{ |
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struct device_node *np = pdev->dev.of_node; |
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struct st_rtc *rtc; |
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struct resource *res; |
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struct rtc_time tm_check; |
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uint32_t mode; |
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int ret = 0; |
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ret = of_property_read_u32(np, "st,lpc-mode", &mode); |
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if (ret) { |
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dev_err(&pdev->dev, "An LPC mode must be provided\n"); |
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return -EINVAL; |
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} |
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/* LPC can either run in RTC or WDT mode */ |
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if (mode != ST_LPC_MODE_RTC) |
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return -ENODEV; |
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rtc = devm_kzalloc(&pdev->dev, sizeof(struct st_rtc), GFP_KERNEL); |
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if (!rtc) |
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return -ENOMEM; |
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spin_lock_init(&rtc->lock); |
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
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rtc->ioaddr = devm_ioremap_resource(&pdev->dev, res); |
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if (IS_ERR(rtc->ioaddr)) |
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return PTR_ERR(rtc->ioaddr); |
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rtc->irq = irq_of_parse_and_map(np, 0); |
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if (!rtc->irq) { |
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dev_err(&pdev->dev, "IRQ missing or invalid\n"); |
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return -EINVAL; |
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} |
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ret = devm_request_irq(&pdev->dev, rtc->irq, st_rtc_handler, 0, |
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pdev->name, rtc); |
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if (ret) { |
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dev_err(&pdev->dev, "Failed to request irq %i\n", rtc->irq); |
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return ret; |
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} |
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enable_irq_wake(rtc->irq); |
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disable_irq(rtc->irq); |
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rtc->clk = clk_get(&pdev->dev, NULL); |
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if (IS_ERR(rtc->clk)) { |
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dev_err(&pdev->dev, "Unable to request clock\n"); |
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return PTR_ERR(rtc->clk); |
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} |
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clk_prepare_enable(rtc->clk); |
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rtc->clkrate = clk_get_rate(rtc->clk); |
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if (!rtc->clkrate) { |
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dev_err(&pdev->dev, "Unable to fetch clock rate\n"); |
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return -EINVAL; |
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} |
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device_set_wakeup_capable(&pdev->dev, 1); |
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platform_set_drvdata(pdev, rtc); |
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/*
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* The RTC-LPC is able to manage date.year > 2038 |
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* but currently the kernel can not manage this date! |
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* If the RTC-LPC has a date.year > 2038 then |
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* it's set to the epoch "Jan 1st 2000" |
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*/ |
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st_rtc_read_time(&pdev->dev, &tm_check); |
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if (tm_check.tm_year >= (2038 - 1900)) { |
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memset(&tm_check, 0, sizeof(tm_check)); |
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tm_check.tm_year = 100; |
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tm_check.tm_mday = 1; |
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st_rtc_set_time(&pdev->dev, &tm_check); |
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} |
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rtc->rtc_dev = rtc_device_register("st-lpc-rtc", &pdev->dev, |
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&st_rtc_ops, THIS_MODULE); |
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if (IS_ERR(rtc->rtc_dev)) { |
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clk_disable_unprepare(rtc->clk); |
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return PTR_ERR(rtc->rtc_dev); |
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} |
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return 0; |
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} |
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static int st_rtc_remove(struct platform_device *pdev) |
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{ |
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struct st_rtc *rtc = platform_get_drvdata(pdev); |
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if (likely(rtc->rtc_dev)) |
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rtc_device_unregister(rtc->rtc_dev); |
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return 0; |
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} |
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#ifdef CONFIG_PM_SLEEP |
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static int st_rtc_suspend(struct device *dev) |
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{ |
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struct st_rtc *rtc = dev_get_drvdata(dev); |
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if (device_may_wakeup(dev)) |
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return 0; |
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writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF); |
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writel_relaxed(0, rtc->ioaddr + LPC_LPA_START_OFF); |
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writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF); |
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return 0; |
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} |
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static int st_rtc_resume(struct device *dev) |
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{ |
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struct st_rtc *rtc = dev_get_drvdata(dev); |
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rtc_alarm_irq_enable(rtc->rtc_dev, 0); |
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/*
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* clean 'rtc->alarm' to allow a new |
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* .set_alarm to the upper RTC layer |
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*/ |
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memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm)); |
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writel_relaxed(0, rtc->ioaddr + LPC_LPA_MSB_OFF); |
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writel_relaxed(0, rtc->ioaddr + LPC_LPA_LSB_OFF); |
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writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF); |
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writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF); |
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writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF); |
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return 0; |
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} |
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#endif |
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static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume); |
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static const struct of_device_id st_rtc_match[] = { |
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{ .compatible = "st,stih407-lpc" }, |
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{} |
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}; |
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MODULE_DEVICE_TABLE(of, st_rtc_match); |
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static struct platform_driver st_rtc_platform_driver = { |
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.driver = { |
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.name = "st-lpc-rtc", |
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.pm = &st_rtc_pm_ops, |
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.of_match_table = st_rtc_match, |
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}, |
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.probe = st_rtc_probe, |
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.remove = st_rtc_remove, |
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}; |
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module_platform_driver(st_rtc_platform_driver); |
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MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver"); |
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MODULE_AUTHOR("David Paris <david.paris@st.com>"); |
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MODULE_LICENSE("GPL"); |
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