linux-kernel - [PATCH v8 2/4] rtc: goldfish: introduce goldfish_ioread32()/goldfish

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Message-Id: <20220115193245.3777833-3-laurent@vivier.eu>
Date:   Sat, 15 Jan 2022 20:32:43 +0100
From:   Laurent Vivier <laurent@...ier.eu>
To:     linux-kernel@...r.kernel.org
Cc:     John Stultz <john.stultz@...aro.org>, linux-rtc@...r.kernel.org,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Arnd Bergmann <arnd@...db.de>, linux-m68k@...ts.linux-m68k.org,
        Laurent Vivier <laurent@...ier.eu>
Subject: [PATCH v8 2/4] rtc: goldfish: introduce goldfish_ioread32()/goldfish_iowrite32()

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@...ier.eu>
---
 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