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linux/drivers/rtc/rtc-rzn1.c
Miquel Raynal 3f34892489 rtc: rzn1: Fix a variable type 
The calculation in ->set_offset() handles both negative and positive
offsets. The 'steps' variable will be checked to be in a specific [-x;
+x] range, which means it must be a signed integer rather than
unsigned.

This also fixes the following smatch warning:

     warn: 'steps' 'true' implies 'steps > 0' is 'true'

Fixes: be4a11cf98 ("rtc: rzn1: Add oscillator offset support")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220520082500.489248-1-miquel.raynal@bootlin.com
2022-05-25 01:24:21 +02:00

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// SPDX-License-Identifier: GPL-2.0+
/*
* Renesas RZ/N1 Real Time Clock interface for Linux
*
* Copyright:
* - 2014 Renesas Electronics Europe Limited
* - 2022 Schneider Electric
*
* Authors:
* - Michel Pollet <michel.pollet@bp.renesas.com>, <buserror@gmail.com>
* - Miquel Raynal <miquel.raynal@bootlin.com>
*/
#include <linux/bcd.h>
#include <linux/init.h>
#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/rtc.h>
#define RZN1_RTC_CTL0 0x00
#define RZN1_RTC_CTL0_SLSB_SUBU 0
#define RZN1_RTC_CTL0_SLSB_SCMP BIT(4)
#define RZN1_RTC_CTL0_AMPM BIT(5)
#define RZN1_RTC_CTL0_CE BIT(7)
#define RZN1_RTC_CTL1 0x04
#define RZN1_RTC_CTL1_ALME BIT(4)
#define RZN1_RTC_CTL2 0x08
#define RZN1_RTC_CTL2_WAIT BIT(0)
#define RZN1_RTC_CTL2_WST BIT(1)
#define RZN1_RTC_CTL2_WUST BIT(5)
#define RZN1_RTC_CTL2_STOPPED (RZN1_RTC_CTL2_WAIT | RZN1_RTC_CTL2_WST)
#define RZN1_RTC_SEC 0x14
#define RZN1_RTC_MIN 0x18
#define RZN1_RTC_HOUR 0x1c
#define RZN1_RTC_WEEK 0x20
#define RZN1_RTC_DAY 0x24
#define RZN1_RTC_MONTH 0x28
#define RZN1_RTC_YEAR 0x2c
#define RZN1_RTC_SUBU 0x38
#define RZN1_RTC_SUBU_DEV BIT(7)
#define RZN1_RTC_SUBU_DECR BIT(6)
#define RZN1_RTC_ALM 0x40
#define RZN1_RTC_ALH 0x44
#define RZN1_RTC_ALW 0x48
#define RZN1_RTC_SECC 0x4c
#define RZN1_RTC_MINC 0x50
#define RZN1_RTC_HOURC 0x54
#define RZN1_RTC_WEEKC 0x58
#define RZN1_RTC_DAYC 0x5c
#define RZN1_RTC_MONTHC 0x60
#define RZN1_RTC_YEARC 0x64
struct rzn1_rtc {
struct rtc_device *rtcdev;
void __iomem *base;
};
static void rzn1_rtc_get_time_snapshot(struct rzn1_rtc *rtc, struct rtc_time *tm)
{
tm->tm_sec = readl(rtc->base + RZN1_RTC_SECC);
tm->tm_min = readl(rtc->base + RZN1_RTC_MINC);
tm->tm_hour = readl(rtc->base + RZN1_RTC_HOURC);
tm->tm_wday = readl(rtc->base + RZN1_RTC_WEEKC);
tm->tm_mday = readl(rtc->base + RZN1_RTC_DAYC);
tm->tm_mon = readl(rtc->base + RZN1_RTC_MONTHC);
tm->tm_year = readl(rtc->base + RZN1_RTC_YEARC);
}
static unsigned int rzn1_rtc_tm_to_wday(struct rtc_time *tm)
{
time64_t time;
unsigned int days;
u32 secs;
time = rtc_tm_to_time64(tm);
days = div_s64_rem(time, 86400, &secs);
/* day of the week, 1970-01-01 was a Thursday */
return (days + 4) % 7;
}
static int rzn1_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct rzn1_rtc *rtc = dev_get_drvdata(dev);
u32 val, secs;
/*
* The RTC was not started or is stopped and thus does not carry the
* proper time/date.
*/
val = readl(rtc->base + RZN1_RTC_CTL2);
if (val & RZN1_RTC_CTL2_STOPPED)
return -EINVAL;
rzn1_rtc_get_time_snapshot(rtc, tm);
secs = readl(rtc->base + RZN1_RTC_SECC);
if (tm->tm_sec != secs)
rzn1_rtc_get_time_snapshot(rtc, tm);
tm->tm_sec = bcd2bin(tm->tm_sec);
tm->tm_min = bcd2bin(tm->tm_min);
tm->tm_hour = bcd2bin(tm->tm_hour);
tm->tm_wday = bcd2bin(tm->tm_wday);
tm->tm_mday = bcd2bin(tm->tm_mday);
tm->tm_mon = bcd2bin(tm->tm_mon);
tm->tm_year = bcd2bin(tm->tm_year);
return 0;
}
static int rzn1_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct rzn1_rtc *rtc = dev_get_drvdata(dev);
u32 val;
int ret;
tm->tm_sec = bin2bcd(tm->tm_sec);
tm->tm_min = bin2bcd(tm->tm_min);
tm->tm_hour = bin2bcd(tm->tm_hour);
tm->tm_wday = bin2bcd(rzn1_rtc_tm_to_wday(tm));
tm->tm_mday = bin2bcd(tm->tm_mday);
tm->tm_mon = bin2bcd(tm->tm_mon);
tm->tm_year = bin2bcd(tm->tm_year);
val = readl(rtc->base + RZN1_RTC_CTL2);
if (!(val & RZN1_RTC_CTL2_STOPPED)) {
/* Hold the counter if it was counting up */
writel(RZN1_RTC_CTL2_WAIT, rtc->base + RZN1_RTC_CTL2);
/* Wait for the counter to stop: two 32k clock cycles */
usleep_range(61, 100);
ret = readl_poll_timeout(rtc->base + RZN1_RTC_CTL2, val,
val & RZN1_RTC_CTL2_WST, 0, 100);
if (ret)
return ret;
}
writel(tm->tm_sec, rtc->base + RZN1_RTC_SEC);
writel(tm->tm_min, rtc->base + RZN1_RTC_MIN);
writel(tm->tm_hour, rtc->base + RZN1_RTC_HOUR);
writel(tm->tm_wday, rtc->base + RZN1_RTC_WEEK);
writel(tm->tm_mday, rtc->base + RZN1_RTC_DAY);
writel(tm->tm_mon, rtc->base + RZN1_RTC_MONTH);
writel(tm->tm_year, rtc->base + RZN1_RTC_YEAR);
writel(0, rtc->base + RZN1_RTC_CTL2);
return 0;
}
static irqreturn_t rzn1_rtc_alarm_irq(int irq, void *dev_id)
{
struct rzn1_rtc *rtc = dev_id;
rtc_update_irq(rtc->rtcdev, 1, RTC_AF | RTC_IRQF);
return IRQ_HANDLED;
}
static int rzn1_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
{
struct rzn1_rtc *rtc = dev_get_drvdata(dev);
u32 ctl1 = readl(rtc->base + RZN1_RTC_CTL1);
if (enable)
ctl1 |= RZN1_RTC_CTL1_ALME;
else
ctl1 &= ~RZN1_RTC_CTL1_ALME;
writel(ctl1, rtc->base + RZN1_RTC_CTL1);
return 0;
}
static int rzn1_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct rzn1_rtc *rtc = dev_get_drvdata(dev);
struct rtc_time *tm = &alrm->time;
unsigned int min, hour, wday, delta_days;
time64_t alarm;
u32 ctl1;
int ret;
ret = rzn1_rtc_read_time(dev, tm);
if (ret)
return ret;
min = readl(rtc->base + RZN1_RTC_ALM);
hour = readl(rtc->base + RZN1_RTC_ALH);
wday = readl(rtc->base + RZN1_RTC_ALW);
tm->tm_sec = 0;
tm->tm_min = bcd2bin(min);
tm->tm_hour = bcd2bin(hour);
delta_days = ((fls(wday) - 1) - tm->tm_wday + 7) % 7;
tm->tm_wday = fls(wday) - 1;
if (delta_days) {
alarm = rtc_tm_to_time64(tm) + (delta_days * 86400);
rtc_time64_to_tm(alarm, tm);
}
ctl1 = readl(rtc->base + RZN1_RTC_CTL1);
alrm->enabled = !!(ctl1 & RZN1_RTC_CTL1_ALME);
return 0;
}
static int rzn1_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct rzn1_rtc *rtc = dev_get_drvdata(dev);
struct rtc_time *tm = &alrm->time, tm_now;
unsigned long alarm, farest;
unsigned int days_ahead, wday;
int ret;
ret = rzn1_rtc_read_time(dev, &tm_now);
if (ret)
return ret;
/* We cannot set alarms more than one week ahead */
farest = rtc_tm_to_time64(&tm_now) + (7 * 86400);
alarm = rtc_tm_to_time64(tm);
if (time_after(alarm, farest))
return -ERANGE;
/* Convert alarm day into week day */
days_ahead = tm->tm_mday - tm_now.tm_mday;
wday = (tm_now.tm_wday + days_ahead) % 7;
writel(bin2bcd(tm->tm_min), rtc->base + RZN1_RTC_ALM);
writel(bin2bcd(tm->tm_hour), rtc->base + RZN1_RTC_ALH);
writel(BIT(wday), rtc->base + RZN1_RTC_ALW);
rzn1_rtc_alarm_irq_enable(dev, alrm->enabled);
return 0;
}
static int rzn1_rtc_read_offset(struct device *dev, long *offset)
{
struct rzn1_rtc *rtc = dev_get_drvdata(dev);
unsigned int ppb_per_step;
bool subtract;
u32 val;
val = readl(rtc->base + RZN1_RTC_SUBU);
ppb_per_step = val & RZN1_RTC_SUBU_DEV ? 1017 : 3051;
subtract = val & RZN1_RTC_SUBU_DECR;
val &= 0x3F;
if (!val)
*offset = 0;
else if (subtract)
*offset = -(((~val) & 0x3F) + 1) * ppb_per_step;
else
*offset = (val - 1) * ppb_per_step;
return 0;
}
static int rzn1_rtc_set_offset(struct device *dev, long offset)
{
struct rzn1_rtc *rtc = dev_get_drvdata(dev);
int stepsh, stepsl, steps;
u32 subu = 0, ctl2;
int ret;
/*
* Check which resolution mode (every 20 or 60s) can be used.
* Between 2 and 124 clock pulses can be added or substracted.
*
* In 20s mode, the minimum resolution is 2 / (32768 * 20) which is
* close to 3051 ppb. In 60s mode, the resolution is closer to 1017.
*/
stepsh = DIV_ROUND_CLOSEST(offset, 1017);
stepsl = DIV_ROUND_CLOSEST(offset, 3051);
if (stepsh >= -0x3E && stepsh <= 0x3E) {
/* 1017 ppb per step */
steps = stepsh;
subu |= RZN1_RTC_SUBU_DEV;
} else if (stepsl >= -0x3E && stepsl <= 0x3E) {
/* 3051 ppb per step */
steps = stepsl;
} else {
return -ERANGE;
}
if (!steps)
return 0;
if (steps > 0) {
subu |= steps + 1;
} else {
subu |= RZN1_RTC_SUBU_DECR;
subu |= (~(-steps - 1)) & 0x3F;
}
ret = readl_poll_timeout(rtc->base + RZN1_RTC_CTL2, ctl2,
!(ctl2 & RZN1_RTC_CTL2_WUST), 100, 2000000);
if (ret)
return ret;
writel(subu, rtc->base + RZN1_RTC_SUBU);
return 0;
}
static const struct rtc_class_ops rzn1_rtc_ops = {
.read_time = rzn1_rtc_read_time,
.set_time = rzn1_rtc_set_time,
.read_alarm = rzn1_rtc_read_alarm,
.set_alarm = rzn1_rtc_set_alarm,
.alarm_irq_enable = rzn1_rtc_alarm_irq_enable,
.read_offset = rzn1_rtc_read_offset,
.set_offset = rzn1_rtc_set_offset,
};
static int rzn1_rtc_probe(struct platform_device *pdev)
{
struct rzn1_rtc *rtc;
int alarm_irq;
int ret;
rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
if (!rtc)
return -ENOMEM;
platform_set_drvdata(pdev, rtc);
rtc->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(rtc->base))
return dev_err_probe(&pdev->dev, PTR_ERR(rtc->base), "Missing reg\n");
alarm_irq = platform_get_irq(pdev, 0);
if (alarm_irq < 0)
return alarm_irq;
rtc->rtcdev = devm_rtc_allocate_device(&pdev->dev);
if (IS_ERR(rtc->rtcdev))
return PTR_ERR(rtc->rtcdev);
rtc->rtcdev->range_min = RTC_TIMESTAMP_BEGIN_2000;
rtc->rtcdev->range_max = RTC_TIMESTAMP_END_2099;
rtc->rtcdev->ops = &rzn1_rtc_ops;
set_bit(RTC_FEATURE_ALARM_RES_MINUTE, rtc->rtcdev->features);
clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->rtcdev->features);
devm_pm_runtime_enable(&pdev->dev);
ret = pm_runtime_resume_and_get(&pdev->dev);
if (ret < 0)
return ret;
/*
* Ensure the clock counter is enabled.
* Set 24-hour mode and possible oscillator offset compensation in SUBU mode.
*/
writel(RZN1_RTC_CTL0_CE | RZN1_RTC_CTL0_AMPM | RZN1_RTC_CTL0_SLSB_SUBU,
rtc->base + RZN1_RTC_CTL0);
/* Disable all interrupts */
writel(0, rtc->base + RZN1_RTC_CTL1);
ret = devm_request_irq(&pdev->dev, alarm_irq, rzn1_rtc_alarm_irq, 0,
dev_name(&pdev->dev), rtc);
if (ret) {
dev_err(&pdev->dev, "RTC timer interrupt not available\n");
goto dis_runtime_pm;
}
ret = devm_rtc_register_device(rtc->rtcdev);
if (ret)
goto dis_runtime_pm;
return 0;
dis_runtime_pm:
pm_runtime_put(&pdev->dev);
return ret;
}
static int rzn1_rtc_remove(struct platform_device *pdev)
{
pm_runtime_put(&pdev->dev);
return 0;
}
static const struct of_device_id rzn1_rtc_of_match[] = {
{ .compatible = "renesas,rzn1-rtc" },
{},
};
MODULE_DEVICE_TABLE(of, rzn1_rtc_of_match);
static struct platform_driver rzn1_rtc_driver = {
.probe = rzn1_rtc_probe,
.remove = rzn1_rtc_remove,
.driver = {
.name = "rzn1-rtc",
.of_match_table = rzn1_rtc_of_match,
},
};
module_platform_driver(rzn1_rtc_driver);
MODULE_AUTHOR("Michel Pollet <Michel.Pollet@bp.renesas.com");
MODULE_AUTHOR("Miquel Raynal <miquel.raynal@bootlin.com");
MODULE_DESCRIPTION("RZ/N1 RTC driver");
MODULE_LICENSE("GPL");
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