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linux-next/drivers/rtc/rtc-lpc24xx.c
Joachim Eastwood c28b42e3ae rtc: add rtc-lpc24xx driver 
Add driver for the RTC found on NXP LPC178x/18xx/408x/43xx devices.
The RTC provides calendar and clock functionality together with
alarm interrupt support.

Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
2015-09-05 13:19:06 +02:00

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/*
* RTC driver for NXP LPC178x/18xx/43xx Real-Time Clock (RTC)
*
* Copyright (C) 2011 NXP Semiconductors
* Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
*/
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
/* LPC24xx RTC register offsets and bits */
#define LPC24XX_ILR 0x00
#define LPC24XX_RTCCIF BIT(0)
#define LPC24XX_RTCALF BIT(1)
#define LPC24XX_CTC 0x04
#define LPC24XX_CCR 0x08
#define LPC24XX_CLKEN BIT(0)
#define LPC178X_CCALEN BIT(4)
#define LPC24XX_CIIR 0x0c
#define LPC24XX_AMR 0x10
#define LPC24XX_ALARM_DISABLE 0xff
#define LPC24XX_CTIME0 0x14
#define LPC24XX_CTIME1 0x18
#define LPC24XX_CTIME2 0x1c
#define LPC24XX_SEC 0x20
#define LPC24XX_MIN 0x24
#define LPC24XX_HOUR 0x28
#define LPC24XX_DOM 0x2c
#define LPC24XX_DOW 0x30
#define LPC24XX_DOY 0x34
#define LPC24XX_MONTH 0x38
#define LPC24XX_YEAR 0x3c
#define LPC24XX_ALSEC 0x60
#define LPC24XX_ALMIN 0x64
#define LPC24XX_ALHOUR 0x68
#define LPC24XX_ALDOM 0x6c
#define LPC24XX_ALDOW 0x70
#define LPC24XX_ALDOY 0x74
#define LPC24XX_ALMON 0x78
#define LPC24XX_ALYEAR 0x7c
/* Macros to read fields in consolidated time (CT) registers */
#define CT0_SECS(x) (((x) >> 0) & 0x3f)
#define CT0_MINS(x) (((x) >> 8) & 0x3f)
#define CT0_HOURS(x) (((x) >> 16) & 0x1f)
#define CT0_DOW(x) (((x) >> 24) & 0x07)
#define CT1_DOM(x) (((x) >> 0) & 0x1f)
#define CT1_MONTH(x) (((x) >> 8) & 0x0f)
#define CT1_YEAR(x) (((x) >> 16) & 0xfff)
#define CT2_DOY(x) (((x) >> 0) & 0xfff)
#define rtc_readl(dev, reg) readl((dev)->rtc_base + (reg))
#define rtc_writel(dev, reg, val) writel((val), (dev)->rtc_base + (reg))
struct lpc24xx_rtc {
void __iomem *rtc_base;
struct rtc_device *rtc;
struct clk *clk_rtc;
struct clk *clk_reg;
};
static int lpc24xx_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
/* Disable RTC during update */
rtc_writel(rtc, LPC24XX_CCR, LPC178X_CCALEN);
rtc_writel(rtc, LPC24XX_SEC, tm->tm_sec);
rtc_writel(rtc, LPC24XX_MIN, tm->tm_min);
rtc_writel(rtc, LPC24XX_HOUR, tm->tm_hour);
rtc_writel(rtc, LPC24XX_DOW, tm->tm_wday);
rtc_writel(rtc, LPC24XX_DOM, tm->tm_mday);
rtc_writel(rtc, LPC24XX_DOY, tm->tm_yday);
rtc_writel(rtc, LPC24XX_MONTH, tm->tm_mon);
rtc_writel(rtc, LPC24XX_YEAR, tm->tm_year);
rtc_writel(rtc, LPC24XX_CCR, LPC24XX_CLKEN | LPC178X_CCALEN);
return 0;
}
static int lpc24xx_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
u32 ct0, ct1, ct2;
ct0 = rtc_readl(rtc, LPC24XX_CTIME0);
ct1 = rtc_readl(rtc, LPC24XX_CTIME1);
ct2 = rtc_readl(rtc, LPC24XX_CTIME2);
tm->tm_sec = CT0_SECS(ct0);
tm->tm_min = CT0_MINS(ct0);
tm->tm_hour = CT0_HOURS(ct0);
tm->tm_wday = CT0_DOW(ct0);
tm->tm_mon = CT1_MONTH(ct1);
tm->tm_mday = CT1_DOM(ct1);
tm->tm_year = CT1_YEAR(ct1);
tm->tm_yday = CT2_DOY(ct2);
return rtc_valid_tm(tm);
}
static int lpc24xx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
{
struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
struct rtc_time *tm = &wkalrm->time;
tm->tm_sec = rtc_readl(rtc, LPC24XX_ALSEC);
tm->tm_min = rtc_readl(rtc, LPC24XX_ALMIN);
tm->tm_hour = rtc_readl(rtc, LPC24XX_ALHOUR);
tm->tm_mday = rtc_readl(rtc, LPC24XX_ALDOM);
tm->tm_wday = rtc_readl(rtc, LPC24XX_ALDOW);
tm->tm_yday = rtc_readl(rtc, LPC24XX_ALDOY);
tm->tm_mon = rtc_readl(rtc, LPC24XX_ALMON);
tm->tm_year = rtc_readl(rtc, LPC24XX_ALYEAR);
wkalrm->enabled = rtc_readl(rtc, LPC24XX_AMR) == 0;
wkalrm->pending = !!(rtc_readl(rtc, LPC24XX_ILR) & LPC24XX_RTCCIF);
return rtc_valid_tm(&wkalrm->time);
}
static int lpc24xx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
{
struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
struct rtc_time *tm = &wkalrm->time;
/* Disable alarm irq during update */
rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
rtc_writel(rtc, LPC24XX_ALSEC, tm->tm_sec);
rtc_writel(rtc, LPC24XX_ALMIN, tm->tm_min);
rtc_writel(rtc, LPC24XX_ALHOUR, tm->tm_hour);
rtc_writel(rtc, LPC24XX_ALDOM, tm->tm_mday);
rtc_writel(rtc, LPC24XX_ALDOW, tm->tm_wday);
rtc_writel(rtc, LPC24XX_ALDOY, tm->tm_yday);
rtc_writel(rtc, LPC24XX_ALMON, tm->tm_mon);
rtc_writel(rtc, LPC24XX_ALYEAR, tm->tm_year);
if (wkalrm->enabled)
rtc_writel(rtc, LPC24XX_AMR, 0);
return 0;
}
static int lpc24xx_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
{
struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
if (enable)
rtc_writel(rtc, LPC24XX_AMR, 0);
else
rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
return 0;
}
static irqreturn_t lpc24xx_rtc_interrupt(int irq, void *data)
{
unsigned long events = RTC_IRQF;
struct lpc24xx_rtc *rtc = data;
u32 rtc_iir;
/* Check interrupt cause */
rtc_iir = rtc_readl(rtc, LPC24XX_ILR);
if (rtc_iir & LPC24XX_RTCALF) {
events |= RTC_AF;
rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
}
/* Clear interrupt status and report event */
rtc_writel(rtc, LPC24XX_ILR, rtc_iir);
rtc_update_irq(rtc->rtc, 1, events);
return IRQ_HANDLED;
}
static const struct rtc_class_ops lpc24xx_rtc_ops = {
.read_time = lpc24xx_rtc_read_time,
.set_time = lpc24xx_rtc_set_time,
.read_alarm = lpc24xx_rtc_read_alarm,
.set_alarm = lpc24xx_rtc_set_alarm,
.alarm_irq_enable = lpc24xx_rtc_alarm_irq_enable,
};
static int lpc24xx_rtc_probe(struct platform_device *pdev)
{
struct lpc24xx_rtc *rtc;
struct resource *res;
int irq, ret;
rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
if (!rtc)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
rtc->rtc_base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(rtc->rtc_base))
return PTR_ERR(rtc->rtc_base);
irq = platform_get_irq(pdev, 0);
if (irq < 0) {
dev_warn(&pdev->dev, "can't get interrupt resource\n");
return irq;
}
rtc->clk_rtc = devm_clk_get(&pdev->dev, "rtc");
if (IS_ERR(rtc->clk_rtc)) {
dev_err(&pdev->dev, "error getting rtc clock\n");
return PTR_ERR(rtc->clk_rtc);
}
rtc->clk_reg = devm_clk_get(&pdev->dev, "reg");
if (IS_ERR(rtc->clk_reg)) {
dev_err(&pdev->dev, "error getting reg clock\n");
return PTR_ERR(rtc->clk_reg);
}
ret = clk_prepare_enable(rtc->clk_rtc);
if (ret) {
dev_err(&pdev->dev, "unable to enable rtc clock\n");
return ret;
}
ret = clk_prepare_enable(rtc->clk_reg);
if (ret) {
dev_err(&pdev->dev, "unable to enable reg clock\n");
goto disable_rtc_clk;
}
platform_set_drvdata(pdev, rtc);
/* Clear any pending interrupts */
rtc_writel(rtc, LPC24XX_ILR, LPC24XX_RTCCIF | LPC24XX_RTCALF);
/* Enable RTC count */
rtc_writel(rtc, LPC24XX_CCR, LPC24XX_CLKEN | LPC178X_CCALEN);
ret = devm_request_irq(&pdev->dev, irq, lpc24xx_rtc_interrupt, 0,
pdev->name, rtc);
if (ret < 0) {
dev_warn(&pdev->dev, "can't request interrupt\n");
goto disable_clks;
}
rtc->rtc = devm_rtc_device_register(&pdev->dev, "lpc24xx-rtc",
&lpc24xx_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc->rtc)) {
dev_err(&pdev->dev, "can't register rtc device\n");
ret = PTR_ERR(rtc->rtc);
goto disable_clks;
}
return 0;
disable_clks:
clk_disable_unprepare(rtc->clk_reg);
disable_rtc_clk:
clk_disable_unprepare(rtc->clk_rtc);
return ret;
}
static int lpc24xx_rtc_remove(struct platform_device *pdev)
{
struct lpc24xx_rtc *rtc = platform_get_drvdata(pdev);
/* Ensure all interrupt sources are masked */
rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
rtc_writel(rtc, LPC24XX_CIIR, 0);
rtc_writel(rtc, LPC24XX_CCR, LPC178X_CCALEN);
clk_disable_unprepare(rtc->clk_rtc);
clk_disable_unprepare(rtc->clk_reg);
return 0;
}
static const struct of_device_id lpc24xx_rtc_match[] = {
{ .compatible = "nxp,lpc1788-rtc" },
{ }
};
MODULE_DEVICE_TABLE(of, lpc24xx_rtc_match);
static struct platform_driver lpc24xx_rtc_driver = {
.probe = lpc24xx_rtc_probe,
.remove = lpc24xx_rtc_remove,
.driver = {
.name = "lpc24xx-rtc",
.of_match_table = lpc24xx_rtc_match,
},
};
module_platform_driver(lpc24xx_rtc_driver);
MODULE_AUTHOR("Kevin Wells <wellsk40@gmail.com>");
MODULE_DESCRIPTION("RTC driver for the LPC178x/18xx/408x/43xx SoCs");
MODULE_LICENSE("GPL");
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