AuxXxilium/linux_dsm_epyc7002
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linux_dsm_epyc7002/drivers/rtc/rtc-r7301.c
Jia-Ju Bai 298c854520 rtc: r7301: Fix a possible sleep-in-atomic bug in rtc7301_set_time 
The driver may sleep under a spinlock.
The function call path is:
rtc7301_set_time (acquire the spinlock)
  usleep_range --> may sleep

To fix it, usleep_range is replaced with udelay.

This bug is found by my static analysis tool(DSAC) and checked by my code review.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
2018-01-12 00:20:34 +01:00

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/*
* EPSON TOYOCOM RTC-7301SF/DG Driver
*
* Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
*
* Based on rtc-rp5c01.c
*
* Datasheet: http://www5.epsondevice.com/en/products/parallel/rtc7301sf.html
*/
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/regmap.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#define DRV_NAME "rtc-r7301"
#define RTC7301_1_SEC 0x0 /* Bank 0 and Band 1 */
#define RTC7301_10_SEC 0x1 /* Bank 0 and Band 1 */
#define RTC7301_AE BIT(3)
#define RTC7301_1_MIN 0x2 /* Bank 0 and Band 1 */
#define RTC7301_10_MIN 0x3 /* Bank 0 and Band 1 */
#define RTC7301_1_HOUR 0x4 /* Bank 0 and Band 1 */
#define RTC7301_10_HOUR 0x5 /* Bank 0 and Band 1 */
#define RTC7301_DAY_OF_WEEK 0x6 /* Bank 0 and Band 1 */
#define RTC7301_1_DAY 0x7 /* Bank 0 and Band 1 */
#define RTC7301_10_DAY 0x8 /* Bank 0 and Band 1 */
#define RTC7301_1_MONTH 0x9 /* Bank 0 */
#define RTC7301_10_MONTH 0xa /* Bank 0 */
#define RTC7301_1_YEAR 0xb /* Bank 0 */
#define RTC7301_10_YEAR 0xc /* Bank 0 */
#define RTC7301_100_YEAR 0xd /* Bank 0 */
#define RTC7301_1000_YEAR 0xe /* Bank 0 */
#define RTC7301_ALARM_CONTROL 0xe /* Bank 1 */
#define RTC7301_ALARM_CONTROL_AIE BIT(0)
#define RTC7301_ALARM_CONTROL_AF BIT(1)
#define RTC7301_TIMER_CONTROL 0xe /* Bank 2 */
#define RTC7301_TIMER_CONTROL_TIE BIT(0)
#define RTC7301_TIMER_CONTROL_TF BIT(1)
#define RTC7301_CONTROL 0xf /* All banks */
#define RTC7301_CONTROL_BUSY BIT(0)
#define RTC7301_CONTROL_STOP BIT(1)
#define RTC7301_CONTROL_BANK_SEL_0 BIT(2)
#define RTC7301_CONTROL_BANK_SEL_1 BIT(3)
struct rtc7301_priv {
struct regmap *regmap;
int irq;
spinlock_t lock;
u8 bank;
};
static const struct regmap_config rtc7301_regmap_config = {
.reg_bits = 32,
.val_bits = 8,
.reg_stride = 4,
};
static u8 rtc7301_read(struct rtc7301_priv *priv, unsigned int reg)
{
int reg_stride = regmap_get_reg_stride(priv->regmap);
unsigned int val;
regmap_read(priv->regmap, reg_stride * reg, &val);
return val & 0xf;
}
static void rtc7301_write(struct rtc7301_priv *priv, u8 val, unsigned int reg)
{
int reg_stride = regmap_get_reg_stride(priv->regmap);
regmap_write(priv->regmap, reg_stride * reg, val);
}
static void rtc7301_update_bits(struct rtc7301_priv *priv, unsigned int reg,
u8 mask, u8 val)
{
int reg_stride = regmap_get_reg_stride(priv->regmap);
regmap_update_bits(priv->regmap, reg_stride * reg, mask, val);
}
static int rtc7301_wait_while_busy(struct rtc7301_priv *priv)
{
int retries = 100;
while (retries-- > 0) {
u8 val;
val = rtc7301_read(priv, RTC7301_CONTROL);
if (!(val & RTC7301_CONTROL_BUSY))
return 0;
udelay(300);
}
return -ETIMEDOUT;
}
static void rtc7301_stop(struct rtc7301_priv *priv)
{
rtc7301_update_bits(priv, RTC7301_CONTROL, RTC7301_CONTROL_STOP,
RTC7301_CONTROL_STOP);
}
static void rtc7301_start(struct rtc7301_priv *priv)
{
rtc7301_update_bits(priv, RTC7301_CONTROL, RTC7301_CONTROL_STOP, 0);
}
static void rtc7301_select_bank(struct rtc7301_priv *priv, u8 bank)
{
u8 val = 0;
if (bank == priv->bank)
return;
if (bank & BIT(0))
val |= RTC7301_CONTROL_BANK_SEL_0;
if (bank & BIT(1))
val |= RTC7301_CONTROL_BANK_SEL_1;
rtc7301_update_bits(priv, RTC7301_CONTROL,
RTC7301_CONTROL_BANK_SEL_0 |
RTC7301_CONTROL_BANK_SEL_1, val);
priv->bank = bank;
}
static void rtc7301_get_time(struct rtc7301_priv *priv, struct rtc_time *tm,
bool alarm)
{
int year;
tm->tm_sec = rtc7301_read(priv, RTC7301_1_SEC);
tm->tm_sec += (rtc7301_read(priv, RTC7301_10_SEC) & ~RTC7301_AE) * 10;
tm->tm_min = rtc7301_read(priv, RTC7301_1_MIN);
tm->tm_min += (rtc7301_read(priv, RTC7301_10_MIN) & ~RTC7301_AE) * 10;
tm->tm_hour = rtc7301_read(priv, RTC7301_1_HOUR);
tm->tm_hour += (rtc7301_read(priv, RTC7301_10_HOUR) & ~RTC7301_AE) * 10;
tm->tm_mday = rtc7301_read(priv, RTC7301_1_DAY);
tm->tm_mday += (rtc7301_read(priv, RTC7301_10_DAY) & ~RTC7301_AE) * 10;
if (alarm) {
tm->tm_wday = -1;
tm->tm_mon = -1;
tm->tm_year = -1;
tm->tm_yday = -1;
tm->tm_isdst = -1;
return;
}
tm->tm_wday = (rtc7301_read(priv, RTC7301_DAY_OF_WEEK) & ~RTC7301_AE);
tm->tm_mon = rtc7301_read(priv, RTC7301_10_MONTH) * 10 +
rtc7301_read(priv, RTC7301_1_MONTH) - 1;
year = rtc7301_read(priv, RTC7301_1000_YEAR) * 1000 +
rtc7301_read(priv, RTC7301_100_YEAR) * 100 +
rtc7301_read(priv, RTC7301_10_YEAR) * 10 +
rtc7301_read(priv, RTC7301_1_YEAR);
tm->tm_year = year - 1900;
}
static void rtc7301_write_time(struct rtc7301_priv *priv, struct rtc_time *tm,
bool alarm)
{
int year;
rtc7301_write(priv, tm->tm_sec % 10, RTC7301_1_SEC);
rtc7301_write(priv, tm->tm_sec / 10, RTC7301_10_SEC);
rtc7301_write(priv, tm->tm_min % 10, RTC7301_1_MIN);
rtc7301_write(priv, tm->tm_min / 10, RTC7301_10_MIN);
rtc7301_write(priv, tm->tm_hour % 10, RTC7301_1_HOUR);
rtc7301_write(priv, tm->tm_hour / 10, RTC7301_10_HOUR);
rtc7301_write(priv, tm->tm_mday % 10, RTC7301_1_DAY);
rtc7301_write(priv, tm->tm_mday / 10, RTC7301_10_DAY);
/* Don't care for alarm register */
rtc7301_write(priv, alarm ? RTC7301_AE : tm->tm_wday,
RTC7301_DAY_OF_WEEK);
if (alarm)
return;
rtc7301_write(priv, (tm->tm_mon + 1) % 10, RTC7301_1_MONTH);
rtc7301_write(priv, (tm->tm_mon + 1) / 10, RTC7301_10_MONTH);
year = tm->tm_year + 1900;
rtc7301_write(priv, year % 10, RTC7301_1_YEAR);
rtc7301_write(priv, (year / 10) % 10, RTC7301_10_YEAR);
rtc7301_write(priv, (year / 100) % 10, RTC7301_100_YEAR);
rtc7301_write(priv, year / 1000, RTC7301_1000_YEAR);
}
static void rtc7301_alarm_irq(struct rtc7301_priv *priv, unsigned int enabled)
{
rtc7301_update_bits(priv, RTC7301_ALARM_CONTROL,
RTC7301_ALARM_CONTROL_AF |
RTC7301_ALARM_CONTROL_AIE,
enabled ? RTC7301_ALARM_CONTROL_AIE : 0);
}
static int rtc7301_read_time(struct device *dev, struct rtc_time *tm)
{
struct rtc7301_priv *priv = dev_get_drvdata(dev);
unsigned long flags;
int err;
spin_lock_irqsave(&priv->lock, flags);
rtc7301_select_bank(priv, 0);
err = rtc7301_wait_while_busy(priv);
if (!err)
rtc7301_get_time(priv, tm, false);
spin_unlock_irqrestore(&priv->lock, flags);
return err ? err : rtc_valid_tm(tm);
}
static int rtc7301_set_time(struct device *dev, struct rtc_time *tm)
{
struct rtc7301_priv *priv = dev_get_drvdata(dev);
unsigned long flags;
spin_lock_irqsave(&priv->lock, flags);
rtc7301_stop(priv);
udelay(300);
rtc7301_select_bank(priv, 0);
rtc7301_write_time(priv, tm, false);
rtc7301_start(priv);
spin_unlock_irqrestore(&priv->lock, flags);
return 0;
}
static int rtc7301_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
struct rtc7301_priv *priv = dev_get_drvdata(dev);
unsigned long flags;
u8 alrm_ctrl;
if (priv->irq <= 0)
return -EINVAL;
spin_lock_irqsave(&priv->lock, flags);
rtc7301_select_bank(priv, 1);
rtc7301_get_time(priv, &alarm->time, true);
alrm_ctrl = rtc7301_read(priv, RTC7301_ALARM_CONTROL);
alarm->enabled = !!(alrm_ctrl & RTC7301_ALARM_CONTROL_AIE);
alarm->pending = !!(alrm_ctrl & RTC7301_ALARM_CONTROL_AF);
spin_unlock_irqrestore(&priv->lock, flags);
return 0;
}
static int rtc7301_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
struct rtc7301_priv *priv = dev_get_drvdata(dev);
unsigned long flags;
if (priv->irq <= 0)
return -EINVAL;
spin_lock_irqsave(&priv->lock, flags);
rtc7301_select_bank(priv, 1);
rtc7301_write_time(priv, &alarm->time, true);
rtc7301_alarm_irq(priv, alarm->enabled);
spin_unlock_irqrestore(&priv->lock, flags);
return 0;
}
static int rtc7301_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct rtc7301_priv *priv = dev_get_drvdata(dev);
unsigned long flags;
if (priv->irq <= 0)
return -EINVAL;
spin_lock_irqsave(&priv->lock, flags);
rtc7301_select_bank(priv, 1);
rtc7301_alarm_irq(priv, enabled);
spin_unlock_irqrestore(&priv->lock, flags);
return 0;
}
static const struct rtc_class_ops rtc7301_rtc_ops = {
.read_time = rtc7301_read_time,
.set_time = rtc7301_set_time,
.read_alarm = rtc7301_read_alarm,
.set_alarm = rtc7301_set_alarm,
.alarm_irq_enable = rtc7301_alarm_irq_enable,
};
static irqreturn_t rtc7301_irq_handler(int irq, void *dev_id)
{
struct rtc_device *rtc = dev_id;
struct rtc7301_priv *priv = dev_get_drvdata(rtc->dev.parent);
unsigned long flags;
irqreturn_t ret = IRQ_NONE;
u8 alrm_ctrl;
spin_lock_irqsave(&priv->lock, flags);
rtc7301_select_bank(priv, 1);
alrm_ctrl = rtc7301_read(priv, RTC7301_ALARM_CONTROL);
if (alrm_ctrl & RTC7301_ALARM_CONTROL_AF) {
ret = IRQ_HANDLED;
rtc7301_alarm_irq(priv, false);
rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);
}
spin_unlock_irqrestore(&priv->lock, flags);
return ret;
}
static void rtc7301_init(struct rtc7301_priv *priv)
{
unsigned long flags;
spin_lock_irqsave(&priv->lock, flags);
rtc7301_select_bank(priv, 2);
rtc7301_write(priv, 0, RTC7301_TIMER_CONTROL);
spin_unlock_irqrestore(&priv->lock, flags);
}
static int __init rtc7301_rtc_probe(struct platform_device *dev)
{
struct resource *res;
void __iomem *regs;
struct rtc7301_priv *priv;
struct rtc_device *rtc;
int ret;
res = platform_get_resource(dev, IORESOURCE_MEM, 0);
if (!res)
return -ENODEV;
priv = devm_kzalloc(&dev->dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
regs = devm_ioremap_resource(&dev->dev, res);
if (IS_ERR(regs))
return PTR_ERR(regs);
priv->regmap = devm_regmap_init_mmio(&dev->dev, regs,
&rtc7301_regmap_config);
if (IS_ERR(priv->regmap))
return PTR_ERR(priv->regmap);
priv->irq = platform_get_irq(dev, 0);
spin_lock_init(&priv->lock);
priv->bank = -1;
rtc7301_init(priv);
platform_set_drvdata(dev, priv);
rtc = devm_rtc_device_register(&dev->dev, DRV_NAME, &rtc7301_rtc_ops,
THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
if (priv->irq > 0) {
ret = devm_request_irq(&dev->dev, priv->irq,
rtc7301_irq_handler, IRQF_SHARED,
dev_name(&dev->dev), rtc);
if (ret) {
priv->irq = 0;
dev_err(&dev->dev, "unable to request IRQ\n");
} else {
device_set_wakeup_capable(&dev->dev, true);
}
}
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int rtc7301_suspend(struct device *dev)
{
struct rtc7301_priv *priv = dev_get_drvdata(dev);
if (device_may_wakeup(dev))
enable_irq_wake(priv->irq);
return 0;
}
static int rtc7301_resume(struct device *dev)
{
struct rtc7301_priv *priv = dev_get_drvdata(dev);
if (device_may_wakeup(dev))
disable_irq_wake(priv->irq);
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(rtc7301_pm_ops, rtc7301_suspend, rtc7301_resume);
static const struct of_device_id rtc7301_dt_match[] = {
{ .compatible = "epson,rtc7301sf" },
{ .compatible = "epson,rtc7301dg" },
{}
};
MODULE_DEVICE_TABLE(of, rtc7301_dt_match);
static struct platform_driver rtc7301_rtc_driver = {
.driver = {
.name = DRV_NAME,
.of_match_table = rtc7301_dt_match,
.pm = &rtc7301_pm_ops,
},
};
module_platform_driver_probe(rtc7301_rtc_driver, rtc7301_rtc_probe);
MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("EPSON TOYOCOM RTC-7301SF/DG Driver");
MODULE_ALIAS("platform:rtc-r7301");
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