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linux/drivers/rtc/rtc-pxa.c
Laurence de Bruxelles 34127b3632 rtc: pxa: fix null pointer dereference 
With the latest stable kernel versions the rtc on the PXA based
Zaurus does not work, when booting I see the following kernel messages:

pxa-rtc pxa-rtc: failed to find rtc clock source
pxa-rtc pxa-rtc: Unable to init SA1100 RTC sub-device
pxa-rtc: probe of pxa-rtc failed with error -2
hctosys: unable to open rtc device (rtc0)

I think this is because commit f2997775b1 ("rtc: sa1100: fix possible
race condition") moved the allocation of the rtc_device struct out of
sa1100_rtc_init and into sa1100_rtc_probe. This means that pxa_rtc_probe
also needs to do allocation for the rtc_device struct, otherwise
sa1100_rtc_init will try to dereference a null pointer. This patch adds
that allocation by copying how sa1100_rtc_probe in
drivers/rtc/rtc-sa1100.c does it; after the IRQs are set up a managed
rtc_device is allocated.

I've tested this patch with `qemu-system-arm -machine akita` and with a
real Zaurus SL-C1000 applied to 4.19, 5.4, and 5.10.

Signed-off-by: Laurence de Bruxelles <lfdebrux@gmail.com>
Fixes: f2997775b1 ("rtc: sa1100: fix possible race condition")
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220101154149.12026-1-lfdebrux@gmail.com
2022-01-05 01:05:17 +01:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Real Time Clock interface for XScale PXA27x and PXA3xx
*
* Copyright (C) 2008 Robert Jarzmik
*/
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/seq_file.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <mach/hardware.h>
#include "rtc-sa1100.h"
#define RTC_DEF_DIVIDER (32768 - 1)
#define RTC_DEF_TRIM 0
#define MAXFREQ_PERIODIC 1000
/*
* PXA Registers and bits definitions
*/
#define RTSR_PICE (1 << 15) /* Periodic interrupt count enable */
#define RTSR_PIALE (1 << 14) /* Periodic interrupt Alarm enable */
#define RTSR_PIAL (1 << 13) /* Periodic interrupt detected */
#define RTSR_SWALE2 (1 << 11) /* RTC stopwatch alarm2 enable */
#define RTSR_SWAL2 (1 << 10) /* RTC stopwatch alarm2 detected */
#define RTSR_SWALE1 (1 << 9) /* RTC stopwatch alarm1 enable */
#define RTSR_SWAL1 (1 << 8) /* RTC stopwatch alarm1 detected */
#define RTSR_RDALE2 (1 << 7) /* RTC alarm2 enable */
#define RTSR_RDAL2 (1 << 6) /* RTC alarm2 detected */
#define RTSR_RDALE1 (1 << 5) /* RTC alarm1 enable */
#define RTSR_RDAL1 (1 << 4) /* RTC alarm1 detected */
#define RTSR_HZE (1 << 3) /* HZ interrupt enable */
#define RTSR_ALE (1 << 2) /* RTC alarm interrupt enable */
#define RTSR_HZ (1 << 1) /* HZ rising-edge detected */
#define RTSR_AL (1 << 0) /* RTC alarm detected */
#define RTSR_TRIG_MASK (RTSR_AL | RTSR_HZ | RTSR_RDAL1 | RTSR_RDAL2\
| RTSR_SWAL1 | RTSR_SWAL2)
#define RYxR_YEAR_S 9
#define RYxR_YEAR_MASK (0xfff << RYxR_YEAR_S)
#define RYxR_MONTH_S 5
#define RYxR_MONTH_MASK (0xf << RYxR_MONTH_S)
#define RYxR_DAY_MASK 0x1f
#define RDxR_WOM_S 20
#define RDxR_WOM_MASK (0x7 << RDxR_WOM_S)
#define RDxR_DOW_S 17
#define RDxR_DOW_MASK (0x7 << RDxR_DOW_S)
#define RDxR_HOUR_S 12
#define RDxR_HOUR_MASK (0x1f << RDxR_HOUR_S)
#define RDxR_MIN_S 6
#define RDxR_MIN_MASK (0x3f << RDxR_MIN_S)
#define RDxR_SEC_MASK 0x3f
#define RTSR 0x08
#define RTTR 0x0c
#define RDCR 0x10
#define RYCR 0x14
#define RDAR1 0x18
#define RYAR1 0x1c
#define RTCPICR 0x34
#define PIAR 0x38
#define rtc_readl(pxa_rtc, reg) \
__raw_readl((pxa_rtc)->base + (reg))
#define rtc_writel(pxa_rtc, reg, value) \
__raw_writel((value), (pxa_rtc)->base + (reg))
struct pxa_rtc {
struct sa1100_rtc sa1100_rtc;
struct resource *ress;
void __iomem *base;
struct rtc_device *rtc;
spinlock_t lock; /* Protects this structure */
};
static u32 ryxr_calc(struct rtc_time *tm)
{
return ((tm->tm_year + 1900) << RYxR_YEAR_S)
| ((tm->tm_mon + 1) << RYxR_MONTH_S)
| tm->tm_mday;
}
static u32 rdxr_calc(struct rtc_time *tm)
{
return ((((tm->tm_mday + 6) / 7) << RDxR_WOM_S) & RDxR_WOM_MASK)
| (((tm->tm_wday + 1) << RDxR_DOW_S) & RDxR_DOW_MASK)
| (tm->tm_hour << RDxR_HOUR_S)
| (tm->tm_min << RDxR_MIN_S)
| tm->tm_sec;
}
static void tm_calc(u32 rycr, u32 rdcr, struct rtc_time *tm)
{
tm->tm_year = ((rycr & RYxR_YEAR_MASK) >> RYxR_YEAR_S) - 1900;
tm->tm_mon = (((rycr & RYxR_MONTH_MASK) >> RYxR_MONTH_S)) - 1;
tm->tm_mday = (rycr & RYxR_DAY_MASK);
tm->tm_wday = ((rycr & RDxR_DOW_MASK) >> RDxR_DOW_S) - 1;
tm->tm_hour = (rdcr & RDxR_HOUR_MASK) >> RDxR_HOUR_S;
tm->tm_min = (rdcr & RDxR_MIN_MASK) >> RDxR_MIN_S;
tm->tm_sec = rdcr & RDxR_SEC_MASK;
}
static void rtsr_clear_bits(struct pxa_rtc *pxa_rtc, u32 mask)
{
u32 rtsr;
rtsr = rtc_readl(pxa_rtc, RTSR);
rtsr &= ~RTSR_TRIG_MASK;
rtsr &= ~mask;
rtc_writel(pxa_rtc, RTSR, rtsr);
}
static void rtsr_set_bits(struct pxa_rtc *pxa_rtc, u32 mask)
{
u32 rtsr;
rtsr = rtc_readl(pxa_rtc, RTSR);
rtsr &= ~RTSR_TRIG_MASK;
rtsr |= mask;
rtc_writel(pxa_rtc, RTSR, rtsr);
}
static irqreturn_t pxa_rtc_irq(int irq, void *dev_id)
{
struct pxa_rtc *pxa_rtc = dev_get_drvdata(dev_id);
u32 rtsr;
unsigned long events = 0;
spin_lock(&pxa_rtc->lock);
/* clear interrupt sources */
rtsr = rtc_readl(pxa_rtc, RTSR);
rtc_writel(pxa_rtc, RTSR, rtsr);
/* temporary disable rtc interrupts */
rtsr_clear_bits(pxa_rtc, RTSR_RDALE1 | RTSR_PIALE | RTSR_HZE);
/* clear alarm interrupt if it has occurred */
if (rtsr & RTSR_RDAL1)
rtsr &= ~RTSR_RDALE1;
/* update irq data & counter */
if (rtsr & RTSR_RDAL1)
events |= RTC_AF | RTC_IRQF;
if (rtsr & RTSR_HZ)
events |= RTC_UF | RTC_IRQF;
if (rtsr & RTSR_PIAL)
events |= RTC_PF | RTC_IRQF;
rtc_update_irq(pxa_rtc->rtc, 1, events);
/* enable back rtc interrupts */
rtc_writel(pxa_rtc, RTSR, rtsr & ~RTSR_TRIG_MASK);
spin_unlock(&pxa_rtc->lock);
return IRQ_HANDLED;
}
static int pxa_rtc_open(struct device *dev)
{
struct pxa_rtc *pxa_rtc = dev_get_drvdata(dev);
int ret;
ret = request_irq(pxa_rtc->sa1100_rtc.irq_1hz, pxa_rtc_irq, 0,
"rtc 1Hz", dev);
if (ret < 0) {
dev_err(dev, "can't get irq %i, err %d\n",
pxa_rtc->sa1100_rtc.irq_1hz, ret);
goto err_irq_1Hz;
}
ret = request_irq(pxa_rtc->sa1100_rtc.irq_alarm, pxa_rtc_irq, 0,
"rtc Alrm", dev);
if (ret < 0) {
dev_err(dev, "can't get irq %i, err %d\n",
pxa_rtc->sa1100_rtc.irq_alarm, ret);
goto err_irq_Alrm;
}
return 0;
err_irq_Alrm:
free_irq(pxa_rtc->sa1100_rtc.irq_1hz, dev);
err_irq_1Hz:
return ret;
}
static void pxa_rtc_release(struct device *dev)
{
struct pxa_rtc *pxa_rtc = dev_get_drvdata(dev);
spin_lock_irq(&pxa_rtc->lock);
rtsr_clear_bits(pxa_rtc, RTSR_PIALE | RTSR_RDALE1 | RTSR_HZE);
spin_unlock_irq(&pxa_rtc->lock);
free_irq(pxa_rtc->sa1100_rtc.irq_1hz, dev);
free_irq(pxa_rtc->sa1100_rtc.irq_alarm, dev);
}
static int pxa_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct pxa_rtc *pxa_rtc = dev_get_drvdata(dev);
spin_lock_irq(&pxa_rtc->lock);
if (enabled)
rtsr_set_bits(pxa_rtc, RTSR_RDALE1);
else
rtsr_clear_bits(pxa_rtc, RTSR_RDALE1);
spin_unlock_irq(&pxa_rtc->lock);
return 0;
}
static int pxa_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct pxa_rtc *pxa_rtc = dev_get_drvdata(dev);
u32 rycr, rdcr;
rycr = rtc_readl(pxa_rtc, RYCR);
rdcr = rtc_readl(pxa_rtc, RDCR);
tm_calc(rycr, rdcr, tm);
return 0;
}
static int pxa_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct pxa_rtc *pxa_rtc = dev_get_drvdata(dev);
rtc_writel(pxa_rtc, RYCR, ryxr_calc(tm));
rtc_writel(pxa_rtc, RDCR, rdxr_calc(tm));
return 0;
}
static int pxa_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct pxa_rtc *pxa_rtc = dev_get_drvdata(dev);
u32 rtsr, ryar, rdar;
ryar = rtc_readl(pxa_rtc, RYAR1);
rdar = rtc_readl(pxa_rtc, RDAR1);
tm_calc(ryar, rdar, &alrm->time);
rtsr = rtc_readl(pxa_rtc, RTSR);
alrm->enabled = (rtsr & RTSR_RDALE1) ? 1 : 0;
alrm->pending = (rtsr & RTSR_RDAL1) ? 1 : 0;
return 0;
}
static int pxa_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct pxa_rtc *pxa_rtc = dev_get_drvdata(dev);
u32 rtsr;
spin_lock_irq(&pxa_rtc->lock);
rtc_writel(pxa_rtc, RYAR1, ryxr_calc(&alrm->time));
rtc_writel(pxa_rtc, RDAR1, rdxr_calc(&alrm->time));
rtsr = rtc_readl(pxa_rtc, RTSR);
if (alrm->enabled)
rtsr |= RTSR_RDALE1;
else
rtsr &= ~RTSR_RDALE1;
rtc_writel(pxa_rtc, RTSR, rtsr);
spin_unlock_irq(&pxa_rtc->lock);
return 0;
}
static int pxa_rtc_proc(struct device *dev, struct seq_file *seq)
{
struct pxa_rtc *pxa_rtc = dev_get_drvdata(dev);
seq_printf(seq, "trim/divider\t: 0x%08x\n", rtc_readl(pxa_rtc, RTTR));
seq_printf(seq, "update_IRQ\t: %s\n",
(rtc_readl(pxa_rtc, RTSR) & RTSR_HZE) ? "yes" : "no");
seq_printf(seq, "periodic_IRQ\t: %s\n",
(rtc_readl(pxa_rtc, RTSR) & RTSR_PIALE) ? "yes" : "no");
seq_printf(seq, "periodic_freq\t: %u\n", rtc_readl(pxa_rtc, PIAR));
return 0;
}
static const struct rtc_class_ops pxa_rtc_ops = {
.read_time = pxa_rtc_read_time,
.set_time = pxa_rtc_set_time,
.read_alarm = pxa_rtc_read_alarm,
.set_alarm = pxa_rtc_set_alarm,
.alarm_irq_enable = pxa_alarm_irq_enable,
.proc = pxa_rtc_proc,
};
static int __init pxa_rtc_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct pxa_rtc *pxa_rtc;
struct sa1100_rtc *sa1100_rtc;
int ret;
pxa_rtc = devm_kzalloc(dev, sizeof(*pxa_rtc), GFP_KERNEL);
if (!pxa_rtc)
return -ENOMEM;
sa1100_rtc = &pxa_rtc->sa1100_rtc;
spin_lock_init(&pxa_rtc->lock);
platform_set_drvdata(pdev, pxa_rtc);
pxa_rtc->ress = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!pxa_rtc->ress) {
dev_err(dev, "No I/O memory resource defined\n");
return -ENXIO;
}
sa1100_rtc->irq_1hz = platform_get_irq(pdev, 0);
if (sa1100_rtc->irq_1hz < 0)
return -ENXIO;
sa1100_rtc->irq_alarm = platform_get_irq(pdev, 1);
if (sa1100_rtc->irq_alarm < 0)
return -ENXIO;
sa1100_rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
if (IS_ERR(sa1100_rtc->rtc))
return PTR_ERR(sa1100_rtc->rtc);
pxa_rtc->base = devm_ioremap(dev, pxa_rtc->ress->start,
resource_size(pxa_rtc->ress));
if (!pxa_rtc->base) {
dev_err(dev, "Unable to map pxa RTC I/O memory\n");
return -ENOMEM;
}
pxa_rtc_open(dev);
sa1100_rtc->rcnr = pxa_rtc->base + 0x0;
sa1100_rtc->rtsr = pxa_rtc->base + 0x8;
sa1100_rtc->rtar = pxa_rtc->base + 0x4;
sa1100_rtc->rttr = pxa_rtc->base + 0xc;
ret = sa1100_rtc_init(pdev, sa1100_rtc);
if (ret) {
dev_err(dev, "Unable to init SA1100 RTC sub-device\n");
return ret;
}
rtsr_clear_bits(pxa_rtc, RTSR_PIALE | RTSR_RDALE1 | RTSR_HZE);
pxa_rtc->rtc = devm_rtc_device_register(&pdev->dev, "pxa-rtc",
&pxa_rtc_ops, THIS_MODULE);
if (IS_ERR(pxa_rtc->rtc)) {
ret = PTR_ERR(pxa_rtc->rtc);
dev_err(dev, "Failed to register RTC device -> %d\n", ret);
return ret;
}
device_init_wakeup(dev, 1);
return 0;
}
static int __exit pxa_rtc_remove(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
pxa_rtc_release(dev);
return 0;
}
#ifdef CONFIG_OF
static const struct of_device_id pxa_rtc_dt_ids[] = {
{ .compatible = "marvell,pxa-rtc" },
{}
};
MODULE_DEVICE_TABLE(of, pxa_rtc_dt_ids);
#endif
#ifdef CONFIG_PM_SLEEP
static int pxa_rtc_suspend(struct device *dev)
{
struct pxa_rtc *pxa_rtc = dev_get_drvdata(dev);
if (device_may_wakeup(dev))
enable_irq_wake(pxa_rtc->sa1100_rtc.irq_alarm);
return 0;
}
static int pxa_rtc_resume(struct device *dev)
{
struct pxa_rtc *pxa_rtc = dev_get_drvdata(dev);
if (device_may_wakeup(dev))
disable_irq_wake(pxa_rtc->sa1100_rtc.irq_alarm);
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(pxa_rtc_pm_ops, pxa_rtc_suspend, pxa_rtc_resume);
static struct platform_driver pxa_rtc_driver = {
.remove = __exit_p(pxa_rtc_remove),
.driver = {
.name = "pxa-rtc",
.of_match_table = of_match_ptr(pxa_rtc_dt_ids),
.pm = &pxa_rtc_pm_ops,
},
};
module_platform_driver_probe(pxa_rtc_driver, pxa_rtc_probe);
MODULE_AUTHOR("Robert Jarzmik <robert.jarzmik@free.fr>");
MODULE_DESCRIPTION("PXA27x/PXA3xx Realtime Clock Driver (RTC)");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:pxa-rtc");
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