391 lines
9.9 KiB
C
391 lines
9.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Real Time Clock (RTC) Driver for i.MX53
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* Copyright (c) 2004-2011 Freescale Semiconductor, Inc.
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* Copyright (c) 2017 Beckhoff Automation GmbH & Co. KG
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*/
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#include <linux/clk.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/mod_devicetable.h>
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#include <linux/platform_device.h>
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#include <linux/pm_wakeirq.h>
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#include <linux/rtc.h>
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#define SRTC_LPPDR_INIT 0x41736166 /* init for glitch detect */
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#define SRTC_LPCR_EN_LP BIT(3) /* lp enable */
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#define SRTC_LPCR_WAE BIT(4) /* lp wakeup alarm enable */
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#define SRTC_LPCR_ALP BIT(7) /* lp alarm flag */
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#define SRTC_LPCR_NSA BIT(11) /* lp non secure access */
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#define SRTC_LPCR_NVE BIT(14) /* lp non valid state exit bit */
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#define SRTC_LPCR_IE BIT(15) /* lp init state exit bit */
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#define SRTC_LPSR_ALP BIT(3) /* lp alarm flag */
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#define SRTC_LPSR_NVES BIT(14) /* lp non-valid state exit status */
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#define SRTC_LPSR_IES BIT(15) /* lp init state exit status */
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#define SRTC_LPSCMR 0x00 /* LP Secure Counter MSB Reg */
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#define SRTC_LPSCLR 0x04 /* LP Secure Counter LSB Reg */
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#define SRTC_LPSAR 0x08 /* LP Secure Alarm Reg */
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#define SRTC_LPCR 0x10 /* LP Control Reg */
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#define SRTC_LPSR 0x14 /* LP Status Reg */
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#define SRTC_LPPDR 0x18 /* LP Power Supply Glitch Detector Reg */
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/* max. number of retries to read registers, 120 was max during test */
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#define REG_READ_TIMEOUT 2000
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struct mxc_rtc_data {
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struct rtc_device *rtc;
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void __iomem *ioaddr;
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struct clk *clk;
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spinlock_t lock; /* protects register access */
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int irq;
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};
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/*
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* This function does write synchronization for writes to the lp srtc block.
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* To take care of the asynchronous CKIL clock, all writes from the IP domain
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* will be synchronized to the CKIL domain.
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* The caller should hold the pdata->lock
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*/
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static void mxc_rtc_sync_lp_locked(struct device *dev, void __iomem *ioaddr)
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{
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unsigned int i;
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/* Wait for 3 CKIL cycles */
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for (i = 0; i < 3; i++) {
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const u32 count = readl(ioaddr + SRTC_LPSCLR);
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unsigned int timeout = REG_READ_TIMEOUT;
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while ((readl(ioaddr + SRTC_LPSCLR)) == count) {
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if (!--timeout) {
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dev_err_once(dev, "SRTC_LPSCLR stuck! Check your hw.\n");
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return;
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}
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}
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}
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}
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/* This function is the RTC interrupt service routine. */
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static irqreturn_t mxc_rtc_interrupt(int irq, void *dev_id)
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{
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struct device *dev = dev_id;
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struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
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void __iomem *ioaddr = pdata->ioaddr;
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unsigned long flags;
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u32 lp_status;
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u32 lp_cr;
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spin_lock_irqsave(&pdata->lock, flags);
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if (clk_enable(pdata->clk)) {
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spin_unlock_irqrestore(&pdata->lock, flags);
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return IRQ_NONE;
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}
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lp_status = readl(ioaddr + SRTC_LPSR);
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lp_cr = readl(ioaddr + SRTC_LPCR);
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/* update irq data & counter */
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if (lp_status & SRTC_LPSR_ALP) {
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if (lp_cr & SRTC_LPCR_ALP)
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rtc_update_irq(pdata->rtc, 1, RTC_AF | RTC_IRQF);
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/* disable further lp alarm interrupts */
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lp_cr &= ~(SRTC_LPCR_ALP | SRTC_LPCR_WAE);
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}
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/* Update interrupt enables */
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writel(lp_cr, ioaddr + SRTC_LPCR);
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/* clear interrupt status */
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writel(lp_status, ioaddr + SRTC_LPSR);
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mxc_rtc_sync_lp_locked(dev, ioaddr);
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clk_disable(pdata->clk);
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spin_unlock_irqrestore(&pdata->lock, flags);
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return IRQ_HANDLED;
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}
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/*
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* Enable clk and aquire spinlock
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* @return 0 if successful; non-zero otherwise.
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*/
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static int mxc_rtc_lock(struct mxc_rtc_data *const pdata)
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{
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int ret;
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spin_lock_irq(&pdata->lock);
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ret = clk_enable(pdata->clk);
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if (ret) {
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spin_unlock_irq(&pdata->lock);
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return ret;
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}
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return 0;
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}
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static int mxc_rtc_unlock(struct mxc_rtc_data *const pdata)
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{
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clk_disable(pdata->clk);
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spin_unlock_irq(&pdata->lock);
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return 0;
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}
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/*
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* This function reads the current RTC time into tm in Gregorian date.
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*
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* @param tm contains the RTC time value upon return
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*
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* @return 0 if successful; non-zero otherwise.
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*/
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static int mxc_rtc_read_time(struct device *dev, struct rtc_time *tm)
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{
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struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
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const int clk_failed = clk_enable(pdata->clk);
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if (!clk_failed) {
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const time64_t now = readl(pdata->ioaddr + SRTC_LPSCMR);
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rtc_time64_to_tm(now, tm);
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clk_disable(pdata->clk);
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return 0;
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}
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return clk_failed;
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}
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/*
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* This function sets the internal RTC time based on tm in Gregorian date.
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*
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* @param tm the time value to be set in the RTC
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*
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* @return 0 if successful; non-zero otherwise.
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*/
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static int mxc_rtc_set_time(struct device *dev, struct rtc_time *tm)
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{
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struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
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time64_t time = rtc_tm_to_time64(tm);
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int ret;
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ret = mxc_rtc_lock(pdata);
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if (ret)
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return ret;
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writel(time, pdata->ioaddr + SRTC_LPSCMR);
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mxc_rtc_sync_lp_locked(dev, pdata->ioaddr);
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return mxc_rtc_unlock(pdata);
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}
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/*
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* This function reads the current alarm value into the passed in \b alrm
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* argument. It updates the \b alrm's pending field value based on the whether
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* an alarm interrupt occurs or not.
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*
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* @param alrm contains the RTC alarm value upon return
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*
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* @return 0 if successful; non-zero otherwise.
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*/
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static int mxc_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
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{
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struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
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void __iomem *ioaddr = pdata->ioaddr;
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int ret;
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ret = mxc_rtc_lock(pdata);
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if (ret)
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return ret;
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rtc_time64_to_tm(readl(ioaddr + SRTC_LPSAR), &alrm->time);
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alrm->pending = !!(readl(ioaddr + SRTC_LPSR) & SRTC_LPSR_ALP);
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return mxc_rtc_unlock(pdata);
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}
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/*
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* Enable/Disable alarm interrupt
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* The caller should hold the pdata->lock
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*/
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static void mxc_rtc_alarm_irq_enable_locked(struct mxc_rtc_data *pdata,
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unsigned int enable)
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{
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u32 lp_cr = readl(pdata->ioaddr + SRTC_LPCR);
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if (enable)
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lp_cr |= (SRTC_LPCR_ALP | SRTC_LPCR_WAE);
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else
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lp_cr &= ~(SRTC_LPCR_ALP | SRTC_LPCR_WAE);
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writel(lp_cr, pdata->ioaddr + SRTC_LPCR);
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}
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static int mxc_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
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{
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struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
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int ret = mxc_rtc_lock(pdata);
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if (ret)
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return ret;
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mxc_rtc_alarm_irq_enable_locked(pdata, enable);
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return mxc_rtc_unlock(pdata);
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}
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/*
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* This function sets the RTC alarm based on passed in alrm.
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*
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* @param alrm the alarm value to be set in the RTC
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*
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* @return 0 if successful; non-zero otherwise.
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*/
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static int mxc_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
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{
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const time64_t time = rtc_tm_to_time64(&alrm->time);
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struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
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int ret = mxc_rtc_lock(pdata);
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if (ret)
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return ret;
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writel((u32)time, pdata->ioaddr + SRTC_LPSAR);
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/* clear alarm interrupt status bit */
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writel(SRTC_LPSR_ALP, pdata->ioaddr + SRTC_LPSR);
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mxc_rtc_sync_lp_locked(dev, pdata->ioaddr);
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mxc_rtc_alarm_irq_enable_locked(pdata, alrm->enabled);
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mxc_rtc_sync_lp_locked(dev, pdata->ioaddr);
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mxc_rtc_unlock(pdata);
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return ret;
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}
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static const struct rtc_class_ops mxc_rtc_ops = {
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.read_time = mxc_rtc_read_time,
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.set_time = mxc_rtc_set_time,
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.read_alarm = mxc_rtc_read_alarm,
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.set_alarm = mxc_rtc_set_alarm,
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.alarm_irq_enable = mxc_rtc_alarm_irq_enable,
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};
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static int mxc_rtc_wait_for_flag(void __iomem *ioaddr, int flag)
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{
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unsigned int timeout = REG_READ_TIMEOUT;
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while (!(readl(ioaddr) & flag)) {
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if (!--timeout)
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return -EBUSY;
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}
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return 0;
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}
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static int mxc_rtc_probe(struct platform_device *pdev)
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{
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struct mxc_rtc_data *pdata;
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void __iomem *ioaddr;
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int ret = 0;
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pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
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if (!pdata)
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return -ENOMEM;
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pdata->ioaddr = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(pdata->ioaddr))
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return PTR_ERR(pdata->ioaddr);
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ioaddr = pdata->ioaddr;
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pdata->clk = devm_clk_get(&pdev->dev, NULL);
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if (IS_ERR(pdata->clk)) {
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dev_err(&pdev->dev, "unable to get rtc clock!\n");
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return PTR_ERR(pdata->clk);
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}
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spin_lock_init(&pdata->lock);
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pdata->irq = platform_get_irq(pdev, 0);
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if (pdata->irq < 0)
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return pdata->irq;
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device_init_wakeup(&pdev->dev, 1);
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ret = dev_pm_set_wake_irq(&pdev->dev, pdata->irq);
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if (ret)
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dev_err(&pdev->dev, "failed to enable irq wake\n");
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ret = clk_prepare_enable(pdata->clk);
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if (ret)
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return ret;
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/* initialize glitch detect */
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writel(SRTC_LPPDR_INIT, ioaddr + SRTC_LPPDR);
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/* clear lp interrupt status */
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writel(0xFFFFFFFF, ioaddr + SRTC_LPSR);
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/* move out of init state */
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writel((SRTC_LPCR_IE | SRTC_LPCR_NSA), ioaddr + SRTC_LPCR);
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ret = mxc_rtc_wait_for_flag(ioaddr + SRTC_LPSR, SRTC_LPSR_IES);
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if (ret) {
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dev_err(&pdev->dev, "Timeout waiting for SRTC_LPSR_IES\n");
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clk_disable_unprepare(pdata->clk);
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return ret;
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}
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/* move out of non-valid state */
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writel((SRTC_LPCR_IE | SRTC_LPCR_NVE | SRTC_LPCR_NSA |
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SRTC_LPCR_EN_LP), ioaddr + SRTC_LPCR);
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ret = mxc_rtc_wait_for_flag(ioaddr + SRTC_LPSR, SRTC_LPSR_NVES);
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if (ret) {
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dev_err(&pdev->dev, "Timeout waiting for SRTC_LPSR_NVES\n");
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clk_disable_unprepare(pdata->clk);
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return ret;
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}
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pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
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if (IS_ERR(pdata->rtc))
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return PTR_ERR(pdata->rtc);
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pdata->rtc->ops = &mxc_rtc_ops;
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pdata->rtc->range_max = U32_MAX;
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clk_disable(pdata->clk);
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platform_set_drvdata(pdev, pdata);
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ret =
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devm_request_irq(&pdev->dev, pdata->irq, mxc_rtc_interrupt, 0,
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pdev->name, &pdev->dev);
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if (ret < 0) {
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dev_err(&pdev->dev, "interrupt not available.\n");
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clk_unprepare(pdata->clk);
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return ret;
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}
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ret = devm_rtc_register_device(pdata->rtc);
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if (ret < 0)
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clk_unprepare(pdata->clk);
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return ret;
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}
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static int mxc_rtc_remove(struct platform_device *pdev)
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{
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struct mxc_rtc_data *pdata = platform_get_drvdata(pdev);
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clk_disable_unprepare(pdata->clk);
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return 0;
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}
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static const struct of_device_id mxc_ids[] = {
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{ .compatible = "fsl,imx53-rtc", },
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{}
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};
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static struct platform_driver mxc_rtc_driver = {
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.driver = {
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.name = "mxc_rtc_v2",
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.of_match_table = mxc_ids,
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},
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.probe = mxc_rtc_probe,
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.remove = mxc_rtc_remove,
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};
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module_platform_driver(mxc_rtc_driver);
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MODULE_AUTHOR("Freescale Semiconductor, Inc.");
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MODULE_DESCRIPTION("Real Time Clock (RTC) Driver for i.MX53");
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MODULE_LICENSE("GPL");
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