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// SPDX-License-Identifier: GPL-2.0-only
/*
* Real time clocks driver for MStar/SigmaStar ARMv7 SoCs.
* Based on "Real Time Clock driver for msb252x." that was contained
* in various MStar kernels.
*
* (C) 2019 Daniel Palmer
* (C) 2021 Romain Perier
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
/* Registers */
#define REG_RTC_CTRL 0x00
#define REG_RTC_FREQ_CW_L 0x04
#define REG_RTC_FREQ_CW_H 0x08
#define REG_RTC_LOAD_VAL_L 0x0C
#define REG_RTC_LOAD_VAL_H 0x10
#define REG_RTC_MATCH_VAL_L 0x14
#define REG_RTC_MATCH_VAL_H 0x18
#define REG_RTC_STATUS_INT 0x1C
#define REG_RTC_CNT_VAL_L 0x20
#define REG_RTC_CNT_VAL_H 0x24
/* Control bits for REG_RTC_CTRL */
#define SOFT_RSTZ_BIT BIT(0)
#define CNT_EN_BIT BIT(1)
#define WRAP_EN_BIT BIT(2)
#define LOAD_EN_BIT BIT(3)
#define READ_EN_BIT BIT(4)
#define INT_MASK_BIT BIT(5)
#define INT_FORCE_BIT BIT(6)
#define INT_CLEAR_BIT BIT(7)
/* Control bits for REG_RTC_STATUS_INT */
#define RAW_INT_BIT BIT(0)
#define ALM_INT_BIT BIT(1)
struct msc313_rtc {
struct rtc_device *rtc_dev;
void __iomem *rtc_base;
};
static int msc313_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
struct msc313_rtc *priv = dev_get_drvdata(dev);
unsigned long seconds;
seconds = readw(priv->rtc_base + REG_RTC_MATCH_VAL_L)
| ((unsigned long)readw(priv->rtc_base + REG_RTC_MATCH_VAL_H) << 16);
rtc_time64_to_tm(seconds, &alarm->time);
if (!(readw(priv->rtc_base + REG_RTC_CTRL) & INT_MASK_BIT))
alarm->enabled = 1;
return 0;
}
static int msc313_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct msc313_rtc *priv = dev_get_drvdata(dev);
u16 reg;
reg = readw(priv->rtc_base + REG_RTC_CTRL);
if (enabled)
reg &= ~INT_MASK_BIT;
else
reg |= INT_MASK_BIT;
writew(reg, priv->rtc_base + REG_RTC_CTRL);
return 0;
}
static int msc313_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
struct msc313_rtc *priv = dev_get_drvdata(dev);
unsigned long seconds;
seconds = rtc_tm_to_time64(&alarm->time);
writew((seconds & 0xFFFF), priv->rtc_base + REG_RTC_MATCH_VAL_L);
writew((seconds >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_MATCH_VAL_H);
msc313_rtc_alarm_irq_enable(dev, alarm->enabled);
return 0;
}
static bool msc313_rtc_get_enabled(struct msc313_rtc *priv)
{
return readw(priv->rtc_base + REG_RTC_CTRL) & CNT_EN_BIT;
}
static void msc313_rtc_set_enabled(struct msc313_rtc *priv)
{
u16 reg;
reg = readw(priv->rtc_base + REG_RTC_CTRL);
reg |= CNT_EN_BIT;
writew(reg, priv->rtc_base + REG_RTC_CTRL);
}
static int msc313_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct msc313_rtc *priv = dev_get_drvdata(dev);
u32 seconds;
u16 reg;
if (!msc313_rtc_get_enabled(priv))
return -EINVAL;
reg = readw(priv->rtc_base + REG_RTC_CTRL);
writew(reg | READ_EN_BIT, priv->rtc_base + REG_RTC_CTRL);
/* Wait for HW latch done */
while (readw(priv->rtc_base + REG_RTC_CTRL) & READ_EN_BIT)
udelay(1);
seconds = readw(priv->rtc_base + REG_RTC_CNT_VAL_L)
| ((unsigned long)readw(priv->rtc_base + REG_RTC_CNT_VAL_H) << 16);
rtc_time64_to_tm(seconds, tm);
return 0;
}
static int msc313_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct msc313_rtc *priv = dev_get_drvdata(dev);
unsigned long seconds;
u16 reg;
seconds = rtc_tm_to_time64(tm);
writew(seconds & 0xFFFF, priv->rtc_base + REG_RTC_LOAD_VAL_L);
writew((seconds >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_LOAD_VAL_H);
/* Enable load for loading value into internal RTC counter */
reg = readw(priv->rtc_base + REG_RTC_CTRL);
writew(reg | LOAD_EN_BIT, priv->rtc_base + REG_RTC_CTRL);
/* Wait for HW latch done */
while (readw(priv->rtc_base + REG_RTC_CTRL) & LOAD_EN_BIT)
udelay(1);
msc313_rtc_set_enabled(priv);
return 0;
}
static const struct rtc_class_ops msc313_rtc_ops = {
.read_time = msc313_rtc_read_time,
.set_time = msc313_rtc_set_time,
.read_alarm = msc313_rtc_read_alarm,
.set_alarm = msc313_rtc_set_alarm,
.alarm_irq_enable = msc313_rtc_alarm_irq_enable,
};
static irqreturn_t msc313_rtc_interrupt(s32 irq, void *dev_id)
{
struct msc313_rtc *priv = dev_get_drvdata(dev_id);
u16 reg;
reg = readw(priv->rtc_base + REG_RTC_STATUS_INT);
if (!(reg & ALM_INT_BIT))
return IRQ_NONE;
reg = readw(priv->rtc_base + REG_RTC_CTRL);
reg |= INT_CLEAR_BIT;
reg &= ~INT_FORCE_BIT;
writew(reg, priv->rtc_base + REG_RTC_CTRL);
rtc_update_irq(priv->rtc_dev, 1, RTC_IRQF | RTC_AF);
return IRQ_HANDLED;
}
static int msc313_rtc_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct msc313_rtc *priv;
unsigned long rate;
struct clk *clk;
int ret;
int irq;
priv = devm_kzalloc(&pdev->dev, sizeof(struct msc313_rtc), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->rtc_base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(priv->rtc_base))
return PTR_ERR(priv->rtc_base);
irq = platform_get_irq(pdev, 0);
if (irq < 0)
return -EINVAL;
priv->rtc_dev = devm_rtc_allocate_device(dev);
if (IS_ERR(priv->rtc_dev))
return PTR_ERR(priv->rtc_dev);
priv->rtc_dev->ops = &msc313_rtc_ops;
priv->rtc_dev->range_max = U32_MAX;
ret = devm_request_irq(dev, irq, msc313_rtc_interrupt, IRQF_SHARED,
dev_name(&pdev->dev), &pdev->dev);
if (ret) {
dev_err(dev, "Could not request IRQ\n");
return ret;
}
clk = devm_clk_get(dev, NULL);
if (IS_ERR(clk)) {
dev_err(dev, "No input reference clock\n");
return PTR_ERR(clk);
}
ret = clk_prepare_enable(clk);
if (ret) {
dev_err(dev, "Failed to enable the reference clock, %d\n", ret);
return ret;
}
ret = devm_add_action_or_reset(dev, (void (*) (void *))clk_disable_unprepare, clk);
if (ret)
return ret;
rate = clk_get_rate(clk);
writew(rate & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_L);
writew((rate >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_H);
platform_set_drvdata(pdev, priv);
return devm_rtc_register_device(priv->rtc_dev);
}
static const struct of_device_id msc313_rtc_of_match_table[] = {
{ .compatible = "mstar,msc313-rtc" },
{ }
};
MODULE_DEVICE_TABLE(of, msc313_rtc_of_match_table);
static struct platform_driver msc313_rtc_driver = {
.probe = msc313_rtc_probe,
.driver = {
.name = "msc313-rtc",
.of_match_table = msc313_rtc_of_match_table,
},
};
module_platform_driver(msc313_rtc_driver);
MODULE_AUTHOR("Daniel Palmer <daniel@thingy.jp>");
MODULE_AUTHOR("Romain Perier <romain.perier@gmail.com>");
MODULE_DESCRIPTION("MStar RTC Driver");
MODULE_LICENSE("GPL v2");
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