[PATCH v8 2/4] rtc: goldfish: introduce goldfish_ioread32()/goldfish_iowrite32()

From: Laurent Vivier
Date: Sat Jan 15 2022 - 14:34:23 EST


The goldfish device always uses the same endianness as the architecture
using it:
https://android.googlesource.com/platform/external/qemu/+/refs/heads/emu-master-dev/hw/timer/goldfish_timer.c#177

On a big-endian machine, the device is also big-endian, on a
little-endian machine the device is little-endian.

So we need to use the right accessor to read/write values to the goldfish
registers: ioread32()/iowrite32() on a little-endian machine,
ioread32be()/iowrite32be() on a big-endian machine.

This patch introduces goldfish_ioread32()/goldfish_iowrite32() that uses
the expected accessor according to the machine endianness.

Signed-off-by: Laurent Vivier <laurent@xxxxxxxxx>
---
drivers/rtc/rtc-goldfish.c | 39 +++++++++++++++++++++++---------------
1 file changed, 24 insertions(+), 15 deletions(-)

diff --git a/drivers/rtc/rtc-goldfish.c b/drivers/rtc/rtc-goldfish.c
index 7ab95d052644..b0cae4729b03 100644
--- a/drivers/rtc/rtc-goldfish.c
+++ b/drivers/rtc/rtc-goldfish.c
@@ -23,6 +23,15 @@
#define TIMER_ALARM_STATUS 0x18
#define TIMER_CLEAR_INTERRUPT 0x1c

+/* goldfish endianness depends on CPU endianness */
+#ifdef CONFIG_CPU_BIG_ENDIAN
+#define goldfish_ioread32 ioread32be
+#define goldfish_iowrite32 iowrite32be
+#else
+#define goldfish_ioread32 ioread32
+#define goldfish_iowrite32 iowrite32
+#endif
+
struct goldfish_rtc {
void __iomem *base;
int irq;
@@ -41,8 +50,8 @@ static int goldfish_rtc_read_alarm(struct device *dev,
rtcdrv = dev_get_drvdata(dev);
base = rtcdrv->base;

- rtc_alarm_low = readl(base + TIMER_ALARM_LOW);
- rtc_alarm_high = readl(base + TIMER_ALARM_HIGH);
+ rtc_alarm_low = goldfish_ioread32(base + TIMER_ALARM_LOW);
+ rtc_alarm_high = goldfish_ioread32(base + TIMER_ALARM_HIGH);
rtc_alarm = (rtc_alarm_high << 32) | rtc_alarm_low;

do_div(rtc_alarm, NSEC_PER_SEC);
@@ -50,7 +59,7 @@ static int goldfish_rtc_read_alarm(struct device *dev,

rtc_time64_to_tm(rtc_alarm, &alrm->time);

- if (readl(base + TIMER_ALARM_STATUS))
+ if (goldfish_ioread32(base + TIMER_ALARM_STATUS))
alrm->enabled = 1;
else
alrm->enabled = 0;
@@ -71,18 +80,18 @@ static int goldfish_rtc_set_alarm(struct device *dev,

if (alrm->enabled) {
rtc_alarm64 = rtc_tm_to_time64(&alrm->time) * NSEC_PER_SEC;
- writel((rtc_alarm64 >> 32), base + TIMER_ALARM_HIGH);
- writel(rtc_alarm64, base + TIMER_ALARM_LOW);
- writel(1, base + TIMER_IRQ_ENABLED);
+ goldfish_iowrite32((rtc_alarm64 >> 32), base + TIMER_ALARM_HIGH);
+ goldfish_iowrite32(rtc_alarm64, base + TIMER_ALARM_LOW);
+ goldfish_iowrite32(1, base + TIMER_IRQ_ENABLED);
} else {
/*
* if this function was called with enabled=0
* then it could mean that the application is
* trying to cancel an ongoing alarm
*/
- rtc_status_reg = readl(base + TIMER_ALARM_STATUS);
+ rtc_status_reg = goldfish_ioread32(base + TIMER_ALARM_STATUS);
if (rtc_status_reg)
- writel(1, base + TIMER_CLEAR_ALARM);
+ goldfish_iowrite32(1, base + TIMER_CLEAR_ALARM);
}

return 0;
@@ -98,9 +107,9 @@ static int goldfish_rtc_alarm_irq_enable(struct device *dev,
base = rtcdrv->base;

if (enabled)
- writel(1, base + TIMER_IRQ_ENABLED);
+ goldfish_iowrite32(1, base + TIMER_IRQ_ENABLED);
else
- writel(0, base + TIMER_IRQ_ENABLED);
+ goldfish_iowrite32(0, base + TIMER_IRQ_ENABLED);

return 0;
}
@@ -110,7 +119,7 @@ static irqreturn_t goldfish_rtc_interrupt(int irq, void *dev_id)
struct goldfish_rtc *rtcdrv = dev_id;
void __iomem *base = rtcdrv->base;

- writel(1, base + TIMER_CLEAR_INTERRUPT);
+ goldfish_iowrite32(1, base + TIMER_CLEAR_INTERRUPT);

rtc_update_irq(rtcdrv->rtc, 1, RTC_IRQF | RTC_AF);

@@ -128,8 +137,8 @@ static int goldfish_rtc_read_time(struct device *dev, struct rtc_time *tm)
rtcdrv = dev_get_drvdata(dev);
base = rtcdrv->base;

- time_low = readl(base + TIMER_TIME_LOW);
- time_high = readl(base + TIMER_TIME_HIGH);
+ time_low = goldfish_ioread32(base + TIMER_TIME_LOW);
+ time_high = goldfish_ioread32(base + TIMER_TIME_HIGH);
time = (time_high << 32) | time_low;

do_div(time, NSEC_PER_SEC);
@@ -149,8 +158,8 @@ static int goldfish_rtc_set_time(struct device *dev, struct rtc_time *tm)
base = rtcdrv->base;

now64 = rtc_tm_to_time64(tm) * NSEC_PER_SEC;
- writel((now64 >> 32), base + TIMER_TIME_HIGH);
- writel(now64, base + TIMER_TIME_LOW);
+ goldfish_iowrite32((now64 >> 32), base + TIMER_TIME_HIGH);
+ goldfish_iowrite32(now64, base + TIMER_TIME_LOW);

return 0;
}
--
2.34.1