[PATCH 0/2] rtc: cmos: Fix non-ACPI (non-x86) platform support

[PATCH 0/2] rtc: cmos: Fix non-ACPI (non-x86) platform support

[Maciej W. Rozycki]

Hi,

 This mini patch series fixes issues introduced recently for non-ACPI 
platforms using `rtc-cmos'.  Please see individual change descriptions for 
details.

 These have been run-time verified with the DECstation (arch/mips/dec).  
Please apply.

  Maciej

[PATCH 1/2] rtc: cmos: Fix non-ACPI undefined reference to `hpet_rtc_interrupt'

[Maciej W. Rozycki]

Fix a commit 311ee9c151ad ("rtc: cmos: allow using ACPI for RTC alarm 
instead of HPET") `rtc-cmos' regression causing a link error:

drivers/rtc/rtc-cmos.o: In function `cmos_platform_probe':
rtc-cmos.c:(.init.text+0x33c): undefined reference to `hpet_rtc_interrupt'
rtc-cmos.c:(.init.text+0x3f4): undefined reference to `hpet_rtc_interrupt'

with non-ACPI platforms using this driver.  The cause is the change of 
the condition guarding the use of `hpet_rtc_interrupt'.

Previously it was a call to `is_hpet_enabled'.  That function is static 
inline and has a hardcoded 0 result for non-ACPI platforms, which imply 
!HPET_EMULATE_RTC.  Consequently the compiler optimized the whole block 
away including the reference to `hpet_rtc_interrupt', which never made 
it to the link stage.

Now the guarding condition is a call to `use_hpet_alarm', which is not 
static inline and therefore the compiler may not be able to prove that 
it actually always returns 0 for non-ACPI platforms.  Consequently the 
build breaks with an unsatisfied reference, because `hpet_rtc_interrupt' 
is nowhere defined at link time.

Fix the problem by marking `use_hpet_alarm' inline.  As the `inline' 
keyword serves as an optimization hint rather than a requirement the 
compiler is still free to choose whether inlining will be beneficial or 
not for ACPI platforms.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Fixes: 311ee9c151ad ("rtc: cmos: allow using ACPI for RTC alarm instead of HPET")
Cc: stable@vger.kernel.org # 4.18+
---
 drivers/rtc/rtc-cmos.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

linux-rtc-cmos-use-hpet-alarm-inline.diff
Index: linux-20180812-4maxp64/drivers/rtc/rtc-cmos.c
===================================================================
--- linux-20180812-4maxp64.orig/drivers/rtc/rtc-cmos.c
+++ linux-20180812-4maxp64/drivers/rtc/rtc-cmos.c
@@ -167,7 +167,7 @@ static inline int hpet_unregister_irq_ha
 #endif
 
 /* Don't use HPET for RTC Alarm event if ACPI Fixed event is used */
-static int use_hpet_alarm(void)
+static inline int use_hpet_alarm(void)
 {
 	return is_hpet_enabled() && !use_acpi_alarm;
 }

[PATCH 2/2] rtc: cmos: Remove the `use_acpi_alarm' module parameter for !ACPI

[Maciej W. Rozycki]

Fix a problem with commit 311ee9c151ad ("rtc: cmos: allow using ACPI for 
RTC alarm instead of HPET") defining `use_acpi_alarm' module parameter 
even for non-ACPI platforms, which ignore it.  Wrap the definition into 
#ifdef CONFIG_ACPI and use a static inline wrapper function, hardcoded 
to return 0 and consequently optimized away for !ACPI, following the 
existing pattern with HPET handling functions.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Fixes: 311ee9c151ad ("rtc: cmos: allow using ACPI for RTC alarm instead of HPET")
Cc: stable@vger.kernel.org # 4.18+
---
 drivers/rtc/rtc-cmos.c |   27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

linux-rtc-cmos-use-acpi-alarm.diff
Index: linux-20180812-4maxp64/drivers/rtc/rtc-cmos.c
===================================================================
--- linux-20180812-4maxp64.orig/drivers/rtc/rtc-cmos.c
+++ linux-20180812-4maxp64/drivers/rtc/rtc-cmos.c
@@ -50,6 +50,7 @@
 /* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */
 #include <linux/mc146818rtc.h>
 
+#ifdef CONFIG_ACPI
 /*
  * Use ACPI SCI to replace HPET interrupt for RTC Alarm event
  *
@@ -61,6 +62,18 @@
 static bool use_acpi_alarm;
 module_param(use_acpi_alarm, bool, 0444);
 
+static inline int cmos_use_acpi_alarm(void)
+{
+	return use_acpi_alarm;
+}
+#else /* !CONFIG_ACPI */
+
+static inline int cmos_use_acpi_alarm(void)
+{
+	return 0;
+}
+#endif
+
 struct cmos_rtc {
 	struct rtc_device	*rtc;
 	struct device		*dev;
@@ -169,7 +182,7 @@ static inline int hpet_unregister_irq_ha
 /* Don't use HPET for RTC Alarm event if ACPI Fixed event is used */
 static inline int use_hpet_alarm(void)
 {
-	return is_hpet_enabled() && !use_acpi_alarm;
+	return is_hpet_enabled() && !cmos_use_acpi_alarm();
 }
 
 /*----------------------------------------------------------------*/
@@ -340,7 +353,7 @@ static void cmos_irq_enable(struct cmos_
 	if (use_hpet_alarm())
 		hpet_set_rtc_irq_bit(mask);
 
-	if ((mask & RTC_AIE) && use_acpi_alarm) {
+	if ((mask & RTC_AIE) && cmos_use_acpi_alarm()) {
 		if (cmos->wake_on)
 			cmos->wake_on(cmos->dev);
 	}
@@ -358,7 +371,7 @@ static void cmos_irq_disable(struct cmos
 	if (use_hpet_alarm())
 		hpet_mask_rtc_irq_bit(mask);
 
-	if ((mask & RTC_AIE) && use_acpi_alarm) {
+	if ((mask & RTC_AIE) && cmos_use_acpi_alarm()) {
 		if (cmos->wake_off)
 			cmos->wake_off(cmos->dev);
 	}
@@ -980,7 +993,7 @@ static int cmos_suspend(struct device *d
 	}
 	spin_unlock_irq(&rtc_lock);
 
-	if ((tmp & RTC_AIE) && !use_acpi_alarm) {
+	if ((tmp & RTC_AIE) && !cmos_use_acpi_alarm()) {
 		cmos->enabled_wake = 1;
 		if (cmos->wake_on)
 			cmos->wake_on(dev);
@@ -1031,7 +1044,7 @@ static void cmos_check_wkalrm(struct dev
 	 * ACPI RTC wake event is cleared after resume from STR,
 	 * ACK the rtc irq here
 	 */
-	if (t_now >= cmos->alarm_expires && use_acpi_alarm) {
+	if (t_now >= cmos->alarm_expires && cmos_use_acpi_alarm()) {
 		cmos_interrupt(0, (void *)cmos->rtc);
 		return;
 	}
@@ -1053,7 +1066,7 @@ static int __maybe_unused cmos_resume(st
 	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
 	unsigned char tmp;
 
-	if (cmos->enabled_wake && !use_acpi_alarm) {
+	if (cmos->enabled_wake && !cmos_use_acpi_alarm()) {
 		if (cmos->wake_off)
 			cmos->wake_off(dev);
 		else
@@ -1132,7 +1145,7 @@ static u32 rtc_handler(void *context)
 	 * Or else, ACPI SCI is enabled during suspend/resume only,
 	 * update rtc irq in that case.
 	 */
-	if (use_acpi_alarm)
+	if (cmos_use_acpi_alarm())
 		cmos_interrupt(0, (void *)cmos->rtc);
 	else {
 		/* Fix me: can we use cmos_interrupt() here as well? */

Re: [PATCH 0/2] rtc: cmos: Fix non-ACPI (non-x86) platform support

[Alexandre Belloni]

On 02/10/2018 02:08:37+0100, Maciej W. Rozycki wrote:
> Hi,
> 
>  This mini patch series fixes issues introduced recently for non-ACPI 
> platforms using `rtc-cmos'.  Please see individual change descriptions for 
> details.
> 
>  These have been run-time verified with the DECstation (arch/mips/dec).  
> Please apply.
> 

Both applied, thanks!

>   Maciej

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com