310 lines
6.9 KiB
C
310 lines
6.9 KiB
C
/*
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* This driver implements a RTC using the Low Power Timer in
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* the System Service of stx5197 STMicroelectronics devices.
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*
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* See ADCS 8101263B for more details on the hardware.
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*
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* Copyright (C) 2010 STMicroelectronics Limited
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* Author: Francesco Virlinzi <francesco.virlinzi@st.com>
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*
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* May be copied or modified under the terms of the GNU General Public
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* License. See linux/COPYING for more information.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/rtc.h>
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#include <linux/delay.h>
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#include <linux/init.h>
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#include <linux/platform_device.h>
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#include <linux/io.h>
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#include <linux/stm/platform.h>
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#include <linux/stm/clk.h>
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#define DRV_NAME "stm-rtc"
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#define DRV_VERSION "0.1"
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#define SS_LOCK_CFG 0x300
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/* Low Power Timer */
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#define LPC_LPT_LSB_OFF 0x200
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#define LPC_LPT_MSB_OFF 0x204
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#define LPC_LPT_START_OFF 0x208
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/* Low Power Alarm */
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#define LPC_LPA_LSB_OFF 0x120
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#define LPC_LPA_LSB_MASK 0xffff
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#define LPC_LPA_MSB_OFF 0x124
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#define LPC_LPA_MSB_MASK 0x00f
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#define LPC_LPA_START_ENABLE (1 << 4)
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#define LPA_CLK 27000000
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struct stm_rtc {
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struct rtc_device *rtc_dev;
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void __iomem *ioaddr;
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struct resource *res;
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spinlock_t lock;
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struct rtc_wkalrm alarm;
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};
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static void _rtc_hw_unlock(struct stm_rtc *rtc)
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{
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writel(0xf0, rtc->ioaddr + SS_LOCK_CFG);
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writel(0x0f, rtc->ioaddr + SS_LOCK_CFG);
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}
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static void _rtc_hw_lock(struct stm_rtc *rtc)
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{
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writel(0x100, rtc->ioaddr + SS_LOCK_CFG);
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}
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static int stm_rtc_read_time(struct device *dev, struct rtc_time *tm)
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{
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struct stm_rtc *rtc = dev_get_drvdata(dev);
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unsigned long long lpt;
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unsigned long lpt_lsb, lpt_msb;
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spin_lock(&rtc->lock);
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do {
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lpt_msb = readl(rtc->ioaddr + LPC_LPT_MSB_OFF);
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lpt_lsb = readl(rtc->ioaddr + LPC_LPT_LSB_OFF);
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} while (readl(rtc->ioaddr + LPC_LPT_MSB_OFF) != lpt_msb);
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lpt = ((unsigned long long)lpt_msb << 32) | lpt_lsb;
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do_div(lpt, LPA_CLK);
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rtc_time_to_tm(lpt, tm);
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spin_unlock(&rtc->lock);
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return 0;
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}
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static int stm_rtc_set_time(struct device *dev, struct rtc_time *tm)
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{
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struct stm_rtc *rtc = dev_get_drvdata(dev);
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unsigned long secs;
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int ret;
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unsigned long long lpt;
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ret = rtc_tm_to_time(tm, &secs);
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if (ret != 0)
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return ret;
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pr_info("%s\n", __func__);
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spin_lock(&rtc->lock);
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lpt = secs * LPA_CLK;
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_rtc_hw_unlock(rtc);
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writel(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF);
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writel(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF);
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writel(1, rtc->ioaddr + LPC_LPT_START_OFF);
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_rtc_hw_lock(rtc);
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spin_unlock(&rtc->lock);
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return 0;
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}
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static int stm_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
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{
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struct stm_rtc *rtc = dev_get_drvdata(dev);
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spin_lock(&rtc->lock);
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memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm));
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spin_unlock(&rtc->lock);
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return 0;
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}
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static int stm_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
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{
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struct stm_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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pr_info("%s\n", __func__);
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stm_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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if (now_secs > alarm_secs)
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return -EINVAL; /* invalid alarm time */
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device_set_wakeup_enable(dev, 1);
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memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm));
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alarm_secs -= now_secs; /* now many secs to fire */
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spin_lock(&rtc->lock);
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_rtc_hw_unlock(rtc);
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writel(alarm_secs & LPC_LPA_LSB_MASK,
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rtc->ioaddr + LPC_LPA_LSB_OFF);
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writel(((alarm_secs >> 16) & LPC_LPA_MSB_MASK)
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| LPC_LPA_START_ENABLE, rtc->ioaddr + LPC_LPA_MSB_OFF);
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_rtc_hw_lock(rtc);
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spin_unlock(&rtc->lock);
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return 0;
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}
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static struct rtc_class_ops stm_rtc_ops = {
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.read_time = stm_rtc_read_time,
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.set_time = stm_rtc_set_time,
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.read_alarm = stm_rtc_read_alarm,
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.set_alarm = stm_rtc_set_alarm,
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};
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#ifdef CONFIG_PM
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static int stm_rtc_resume(struct device *dev)
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{
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struct stm_rtc *rtc = dev_get_drvdata(dev);
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pr_info("Resetting rtc-lpc devices\n");
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/*
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* it needs to clean the 'rtc->alarm' to allow
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* a new .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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spin_lock(&rtc->lock);
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/* turn-off the alarm */
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_rtc_hw_unlock(rtc);
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writel(0, rtc->ioaddr + LPC_LPA_LSB_OFF);
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writel(0, rtc->ioaddr + LPC_LPA_MSB_OFF);
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_rtc_hw_lock(rtc);
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spin_unlock(&rtc->lock);
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return 0;
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}
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static int stm_rtc_suspend(struct device *dev)
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{
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if (device_may_wakeup(dev))
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return 0;
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return stm_rtc_resume(dev);
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}
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static struct dev_pm_ops stm_rtc_pm_ops = {
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.suspend = stm_rtc_suspend, /* on standby/memstandby */
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.resume = stm_rtc_resume,
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};
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#endif
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static int __devinit stm_rtc_probe(struct platform_device *pdev)
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{
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struct rtc_time tm_check;
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struct stm_rtc *rtc;
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struct resource *res;
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int size;
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int ret = 0;
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rtc = kzalloc(sizeof(struct stm_rtc), GFP_KERNEL);
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if (unlikely(!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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if (unlikely(res == NULL)) {
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dev_err(&pdev->dev, "No IO resource\n");
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ret = -ENOENT;
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goto err_badres;
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}
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size = res->end - res->start + 1;
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/*
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* Memory can not be request because shared between several IPs..
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*/
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rtc->ioaddr = ioremap(res->start, size);
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if (!rtc->ioaddr) {
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ret = -EINVAL;
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goto err_badres;
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}
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platform_set_drvdata(pdev, rtc);
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device_set_wakeup_capable(&pdev->dev, 1);
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rtc->rtc_dev = rtc_device_register(DRV_NAME, &pdev->dev,
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&stm_rtc_ops, THIS_MODULE);
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if (IS_ERR(rtc->rtc_dev)) {
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ret = PTR_ERR(rtc->rtc_dev);
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goto err_badreg;
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}
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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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stm_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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/*
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* FIXME:
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* the 'tm_check.tm_mday' should be set to zero but the func-
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* tions rtc_tm_to_time and rtc_time_to_time aren't coherent.
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*/
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tm_check.tm_mday = 1;
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stm_rtc_set_time(&pdev->dev, &tm_check);
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}
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return ret;
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err_badreg:
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iounmap(rtc->ioaddr);
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err_badres:
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kfree(rtc);
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return ret;
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}
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static int __devexit stm_rtc_remove(struct platform_device *pdev)
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{
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struct stm_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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iounmap(rtc->ioaddr);
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platform_set_drvdata(pdev, NULL);
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kfree(rtc);
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return 0;
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}
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static struct platform_driver stm_rtc_platform_driver = {
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.driver = {
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.name = DRV_NAME,
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.owner = THIS_MODULE,
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#ifdef CONFIG_PM
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.pm = &stm_rtc_pm_ops,
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#endif
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},
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.probe = stm_rtc_probe,
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.remove = __devexit_p(stm_rtc_remove),
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};
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static int __init stm_rtc_init(void)
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{
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return platform_driver_register(&stm_rtc_platform_driver);
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}
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static void __exit stm_rtc_exit(void)
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{
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platform_driver_unregister(&stm_rtc_platform_driver);
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}
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module_init(stm_rtc_init);
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module_exit(stm_rtc_exit);
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MODULE_DESCRIPTION("STMicroelectronics STx5197 RTC driver");
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MODULE_VERSION(DRV_VERSION);
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MODULE_LICENSE("GPL");
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