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// SPDX-License-Identifier: GPL-2.0+
/*
* APM X-Gene SoC Real Time Clock Driver
*
* Copyright (c) 2014, Applied Micro Circuits Corporation
* Author: Rameshwar Prasad Sahu <rsahu@apm.com>
* Loc Ho <lho@apm.com>
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/slab.h>
/* RTC CSR Registers */
#define RTC_CCVR 0x00
#define RTC_CMR 0x04
#define RTC_CLR 0x08
#define RTC_CCR 0x0C
#define RTC_CCR_IE BIT(0)
#define RTC_CCR_MASK BIT(1)
#define RTC_CCR_EN BIT(2)
#define RTC_CCR_WEN BIT(3)
#define RTC_STAT 0x10
#define RTC_STAT_BIT BIT(0)
#define RTC_RSTAT 0x14
#define RTC_EOI 0x18
#define RTC_VER 0x1C
struct xgene_rtc_dev {
struct rtc_device *rtc;
struct device *dev;
void __iomem *csr_base;
struct clk *clk;
unsigned int irq_wake;
unsigned int irq_enabled;
};
static int xgene_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
rtc_time64_to_tm(readl(pdata->csr_base + RTC_CCVR), tm);
return 0;
}
static int xgene_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
/*
* NOTE: After the following write, the RTC_CCVR is only reflected
* after the update cycle of 1 seconds.
*/
writel((u32)rtc_tm_to_time64(tm), pdata->csr_base + RTC_CLR);
readl(pdata->csr_base + RTC_CLR); /* Force a barrier */
return 0;
}
static int xgene_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
/* If possible, CMR should be read here */
rtc_time64_to_tm(0, &alrm->time);
alrm->enabled = readl(pdata->csr_base + RTC_CCR) & RTC_CCR_IE;
return 0;
}
static int xgene_rtc_alarm_irq_enable(struct device *dev, u32 enabled)
{
struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
u32 ccr;
ccr = readl(pdata->csr_base + RTC_CCR);
if (enabled) {
ccr &= ~RTC_CCR_MASK;
ccr |= RTC_CCR_IE;
} else {
ccr &= ~RTC_CCR_IE;
ccr |= RTC_CCR_MASK;
}
writel(ccr, pdata->csr_base + RTC_CCR);
return 0;
}
static int xgene_rtc_alarm_irq_enabled(struct device *dev)
{
struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
return readl(pdata->csr_base + RTC_CCR) & RTC_CCR_IE ? 1 : 0;
}
static int xgene_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
writel((u32)rtc_tm_to_time64(&alrm->time), pdata->csr_base + RTC_CMR);
xgene_rtc_alarm_irq_enable(dev, alrm->enabled);
return 0;
}
static const struct rtc_class_ops xgene_rtc_ops = {
.read_time = xgene_rtc_read_time,
.set_time = xgene_rtc_set_time,
.read_alarm = xgene_rtc_read_alarm,
.set_alarm = xgene_rtc_set_alarm,
.alarm_irq_enable = xgene_rtc_alarm_irq_enable,
};
static irqreturn_t xgene_rtc_interrupt(int irq, void *id)
{
struct xgene_rtc_dev *pdata = id;
/* Check if interrupt asserted */
if (!(readl(pdata->csr_base + RTC_STAT) & RTC_STAT_BIT))
return IRQ_NONE;
/* Clear interrupt */
readl(pdata->csr_base + RTC_EOI);
rtc_update_irq(pdata->rtc, 1, RTC_IRQF | RTC_AF);
return IRQ_HANDLED;
}
static int xgene_rtc_probe(struct platform_device *pdev)
{
struct xgene_rtc_dev *pdata;
struct resource *res;
int ret;
int irq;
pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
if (!pdata)
return -ENOMEM;
platform_set_drvdata(pdev, pdata);
pdata->dev = &pdev->dev;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
pdata->csr_base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(pdata->csr_base))
return PTR_ERR(pdata->csr_base);
pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
if (IS_ERR(pdata->rtc))
return PTR_ERR(pdata->rtc);
irq = platform_get_irq(pdev, 0);
if (irq < 0)
return irq;
ret = devm_request_irq(&pdev->dev, irq, xgene_rtc_interrupt, 0,
dev_name(&pdev->dev), pdata);
if (ret) {
dev_err(&pdev->dev, "Could not request IRQ\n");
return ret;
}
pdata->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(pdata->clk)) {
dev_err(&pdev->dev, "Couldn't get the clock for RTC\n");
return -ENODEV;
}
ret = clk_prepare_enable(pdata->clk);
if (ret)
return ret;
/* Turn on the clock and the crystal */
writel(RTC_CCR_EN, pdata->csr_base + RTC_CCR);
ret = device_init_wakeup(&pdev->dev, 1);
if (ret) {
clk_disable_unprepare(pdata->clk);
return ret;
}
/* HW does not support update faster than 1 seconds */
pdata->rtc->uie_unsupported = 1;
pdata->rtc->ops = &xgene_rtc_ops;
pdata->rtc->range_max = U32_MAX;
ret = rtc_register_device(pdata->rtc);
if (ret) {
clk_disable_unprepare(pdata->clk);
return ret;
}
return 0;
}
static int xgene_rtc_remove(struct platform_device *pdev)
{
struct xgene_rtc_dev *pdata = platform_get_drvdata(pdev);
xgene_rtc_alarm_irq_enable(&pdev->dev, 0);
device_init_wakeup(&pdev->dev, 0);
clk_disable_unprepare(pdata->clk);
return 0;
}
static int __maybe_unused xgene_rtc_suspend(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct xgene_rtc_dev *pdata = platform_get_drvdata(pdev);
int irq;
irq = platform_get_irq(pdev, 0);
/*
* If this RTC alarm will be used for waking the system up,
* don't disable it of course. Else we just disable the alarm
* and await suspension.
*/
if (device_may_wakeup(&pdev->dev)) {
if (!enable_irq_wake(irq))
pdata->irq_wake = 1;
} else {
pdata->irq_enabled = xgene_rtc_alarm_irq_enabled(dev);
xgene_rtc_alarm_irq_enable(dev, 0);
clk_disable_unprepare(pdata->clk);
}
return 0;
}
static int __maybe_unused xgene_rtc_resume(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct xgene_rtc_dev *pdata = platform_get_drvdata(pdev);
int irq;
int rc;
irq = platform_get_irq(pdev, 0);
if (device_may_wakeup(&pdev->dev)) {
if (pdata->irq_wake) {
disable_irq_wake(irq);
pdata->irq_wake = 0;
}
} else {
rc = clk_prepare_enable(pdata->clk);
if (rc) {
dev_err(dev, "Unable to enable clock error %d\n", rc);
return rc;
}
xgene_rtc_alarm_irq_enable(dev, pdata->irq_enabled);
}
return 0;
}
static SIMPLE_DEV_PM_OPS(xgene_rtc_pm_ops, xgene_rtc_suspend, xgene_rtc_resume);
#ifdef CONFIG_OF
static const struct of_device_id xgene_rtc_of_match[] = {
{.compatible = "apm,xgene-rtc" },
{ }
};
MODULE_DEVICE_TABLE(of, xgene_rtc_of_match);
#endif
static struct platform_driver xgene_rtc_driver = {
.probe = xgene_rtc_probe,
.remove = xgene_rtc_remove,
.driver = {
.name = "xgene-rtc",
.pm = &xgene_rtc_pm_ops,
.of_match_table = of_match_ptr(xgene_rtc_of_match),
},
};
module_platform_driver(xgene_rtc_driver);
MODULE_DESCRIPTION("APM X-Gene SoC RTC driver");
MODULE_AUTHOR("Rameshwar Sahu <rsahu@apm.com>");
MODULE_LICENSE("GPL");
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