rtc: st: Add new driver for ST's LPC RTC
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>
This commit is contained in:
Lee Jones
parent
5cb69745da
commit
b5b2bdfc28
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@ -1510,6 +1510,17 @@ config RTC_DRV_SIRFSOC
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Say "yes" here to support the real time clock on SiRF SOC chips.
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This driver can also be built as a module called rtc-sirfsoc.
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config RTC_DRV_ST_LPC
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tristate "STMicroelectronics LPC RTC"
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depends on ARCH_STI
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depends on OF
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help
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Say Y here to include STMicroelectronics Low Power Controller
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(LPC) based RTC support.
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To compile this driver as a module, choose M here: the
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module will be called rtc-st-lpc.
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config RTC_DRV_MOXART
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tristate "MOXA ART RTC"
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depends on ARCH_MOXART || COMPILE_TEST
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@ -153,4 +153,5 @@ obj-$(CONFIG_RTC_DRV_WM8350) += rtc-wm8350.o
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obj-$(CONFIG_RTC_DRV_X1205) += rtc-x1205.o
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obj-$(CONFIG_RTC_DRV_XGENE) += rtc-xgene.o
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obj-$(CONFIG_RTC_DRV_SIRFSOC) += rtc-sirfsoc.o
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obj-$(CONFIG_RTC_DRV_ST_LPC) += rtc-st-lpc.o
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obj-$(CONFIG_RTC_DRV_MOXART) += rtc-moxart.o
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@ -0,0 +1,354 @@
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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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