[patch 0/3] Implement CONFIG_HPET_EMULATE_RTC for RTC_DRV_CMOS

[patch 0/3] Implement CONFIG_HPET_EMULATE_RTC for RTC_DRV_CMOS

[Bernhard Walle]

The new rtc-cmos driver misses HPET support. If the hardware has HPET enabled,
then interrupts don't work for the rtc-cmos driver which results in RTC_AIE*,
RTC_PIE* and RTC_ALM being unusable. This affects hwclock from util-linux-ng
at least on i386 since that uses RTC_PIE_ON. (For x86-64, a polling method is
used for unknown reasons.)

This patch series now

  1. export the functions from arch/x86/kernel/hpet.c that the old char/rtc
     driver uses to work around that problem,

  2. makes it possible to compile the old rtc driver as module, while still
     having CONFIG_HPET_EMULATE_RTC enabled and

  3. makes use of the exported functions in (1) in the new rtc-cmos driver.

The design is not changed. Please review and give me feedback!

This patch series is against 2.6.24-rc5-mm1. It passes the test in
Documentation/rtc.txt after http://lkml.org/lkml/2007/12/20/249 is applied.


Signed-off-by: Bernhard Walle <bwalle@suse.de>

[patch 1/3] Make CONFIG_HPET_EMULATE_RTC usable from modules

[Bernhard Walle]

[-- Attachment #1: hpet-operations-usable-from-module --]
[-- Type: text/plain, Size: 4695 bytes --]

This patch makes the RTC emulation functions in arch/x86/kernel/hpet.c usable
for kernel modules. It

  - exports the functions (EXPORT_SYMBOL_GPL()),
  - adds an interface to register the interrupt callback function
    instead of using only a fixed callback function and
  - replaces the rtc_get_rtc_time() function which depends on
    CONFIG_RTC with a call to get_rtc_time() which is defined in
    include/asm-generic/rtc.h.

The only dependency to CONFIG_RTC is the call to rtc_interrupt() which is
removed by the next patch. After this, there's no (code) dependency of
this functions to CONFIG_RTC=y any more.


Signed-off-by: Bernhard Walle <bwalle@suse.de>

---
 arch/x86/kernel/hpet.c |   47 ++++++++++++++++++++++++++++++++++++++++++++++-
 include/asm-x86/hpet.h |    3 +++
 2 files changed, 49 insertions(+), 1 deletion(-)

--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -107,6 +107,7 @@ int is_hpet_enabled(void)
 {
 	return is_hpet_capable() && hpet_legacy_int_enabled;
 }
+EXPORT_SYMBOL_GPL(is_hpet_enabled);
 
 /*
  * When the hpet driver (/dev/hpet) is enabled, we need to reserve
@@ -478,6 +479,7 @@ void hpet_disable(void)
  */
 #include <linux/mc146818rtc.h>
 #include <linux/rtc.h>
+#include <asm/rtc.h>
 
 #define DEFAULT_RTC_INT_FREQ	64
 #define DEFAULT_RTC_SHIFT	6
@@ -492,6 +494,38 @@ static unsigned long hpet_default_delta;
 static unsigned long hpet_pie_delta;
 static unsigned long hpet_pie_limit;
 
+static rtc_irq_handler irq_handler;
+
+/*
+ * Registers a IRQ handler.
+ */
+int hpet_register_irq_handler(rtc_irq_handler handler)
+{
+	if (!is_hpet_enabled())
+		return -ENODEV;
+	if (irq_handler)
+		return -EBUSY;
+
+	irq_handler = handler;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hpet_register_irq_handler);
+
+/*
+ * Deregisters the IRQ handler registered with hpet_register_irq_handler()
+ * and does cleanup.
+ */
+void hpet_unregister_irq_handler(rtc_irq_handler handler)
+{
+	if (!is_hpet_enabled())
+		return;
+
+	irq_handler = NULL;
+	hpet_rtc_flags = 0;
+}
+EXPORT_SYMBOL_GPL(hpet_unregister_irq_handler);
+
 /*
  * Timer 1 for RTC emulation. We use one shot mode, as periodic mode
  * is not supported by all HPET implementations for timer 1.
@@ -533,6 +567,7 @@ int hpet_rtc_timer_init(void)
 
 	return 1;
 }
+EXPORT_SYMBOL_GPL(hpet_rtc_timer_init);
 
 /*
  * The functions below are called from rtc driver.
@@ -547,6 +582,7 @@ int hpet_mask_rtc_irq_bit(unsigned long 
 	hpet_rtc_flags &= ~bit_mask;
 	return 1;
 }
+EXPORT_SYMBOL_GPL(hpet_mask_rtc_irq_bit);
 
 int hpet_set_rtc_irq_bit(unsigned long bit_mask)
 {
@@ -562,6 +598,7 @@ int hpet_set_rtc_irq_bit(unsigned long b
 
 	return 1;
 }
+EXPORT_SYMBOL_GPL(hpet_set_rtc_irq_bit);
 
 int hpet_set_alarm_time(unsigned char hrs, unsigned char min,
 			unsigned char sec)
@@ -575,6 +612,7 @@ int hpet_set_alarm_time(unsigned char hr
 
 	return 1;
 }
+EXPORT_SYMBOL_GPL(hpet_set_alarm_time);
 
 int hpet_set_periodic_freq(unsigned long freq)
 {
@@ -593,11 +631,13 @@ int hpet_set_periodic_freq(unsigned long
 	}
 	return 1;
 }
+EXPORT_SYMBOL_GPL(hpet_set_periodic_freq);
 
 int hpet_rtc_dropped_irq(void)
 {
 	return is_hpet_enabled();
 }
+EXPORT_SYMBOL_GPL(hpet_rtc_dropped_irq);
 
 static void hpet_rtc_timer_reinit(void)
 {
@@ -641,9 +681,10 @@ irqreturn_t hpet_rtc_interrupt(int irq, 
 	unsigned long rtc_int_flag = 0;
 
 	hpet_rtc_timer_reinit();
+	memset(&curr_time, 0, sizeof(struct rtc_time));
 
 	if (hpet_rtc_flags & (RTC_UIE | RTC_AIE))
-		rtc_get_rtc_time(&curr_time);
+		get_rtc_time(&curr_time);
 
 	if (hpet_rtc_flags & RTC_UIE &&
 	    curr_time.tm_sec != hpet_prev_update_sec) {
@@ -665,8 +706,12 @@ irqreturn_t hpet_rtc_interrupt(int irq, 
 
 	if (rtc_int_flag) {
 		rtc_int_flag |= (RTC_IRQF | (RTC_NUM_INTS << 8));
+		if (irq_handler)
+			irq_handler(rtc_int_flag, dev_id);
+
 		rtc_interrupt(rtc_int_flag, dev_id);
 	}
 	return IRQ_HANDLED;
 }
+EXPORT_SYMBOL_GPL(hpet_rtc_interrupt);
 #endif
--- a/include/asm-x86/hpet.h
+++ b/include/asm-x86/hpet.h
@@ -69,6 +69,7 @@ extern void force_hpet_resume(void);
 
 #include <linux/interrupt.h>
 
+typedef irqreturn_t (*rtc_irq_handler)(int interrupt, void *cookie);
 extern int hpet_mask_rtc_irq_bit(unsigned long bit_mask);
 extern int hpet_set_rtc_irq_bit(unsigned long bit_mask);
 extern int hpet_set_alarm_time(unsigned char hrs, unsigned char min,
@@ -77,6 +78,8 @@ extern int hpet_set_periodic_freq(unsign
 extern int hpet_rtc_dropped_irq(void);
 extern int hpet_rtc_timer_init(void);
 extern irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id);
+extern int hpet_register_irq_handler(rtc_irq_handler handler);
+extern void hpet_unregister_irq_handler(rtc_irq_handler handler);
 
 #endif /* CONFIG_HPET_EMULATE_RTC */
 

[patch 2/3] Use the IRQ callback interface in (old) RTC driver

[Bernhard Walle]

[-- Attachment #1: use-exported-operations-in-rtc --]
[-- Type: text/plain, Size: 2508 bytes --]

That function uses the new registration callback mechanism which was added in
the previous patch in the old RTC driver. It also removes the direct
rtc_interrupt() call from arch/x86/kernel/hpetc.c so that there's finally
no (code) dependency to CONFIG_RTC in arch/x86/kernel/hpet.c.

Because of this, it's possible to compile the drivers/char/rtc.ko driver
as module and still use the HPET emulation functionality. This is also
expressed in Kconfig.


Signed-off-by: Bernhard Walle <bwalle@suse.de>

---
 arch/x86/Kconfig       |    2 +-
 arch/x86/kernel/hpet.c |    2 --
 drivers/char/rtc.c     |   15 ++++++++++++++-
 3 files changed, 15 insertions(+), 4 deletions(-)

--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -405,7 +405,7 @@ config HPET_TIMER
 
 config HPET_EMULATE_RTC
 	def_bool y
-	depends on HPET_TIMER && RTC=y
+	depends on HPET_TIMER && (RTC=y || RTC=m)
 
 # Mark as embedded because too many people got it wrong.
 # The code disables itself when not needed.
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -708,8 +708,6 @@ irqreturn_t hpet_rtc_interrupt(int irq, 
 		rtc_int_flag |= (RTC_IRQF | (RTC_NUM_INTS << 8));
 		if (irq_handler)
 			irq_handler(rtc_int_flag, dev_id);
-
-		rtc_interrupt(rtc_int_flag, dev_id);
 	}
 	return IRQ_HANDLED;
 }
--- a/drivers/char/rtc.c
+++ b/drivers/char/rtc.c
@@ -110,6 +110,8 @@ static int rtc_has_irq = 1;
 #define hpet_set_rtc_irq_bit(arg)		0
 #define hpet_rtc_timer_init()			do { } while (0)
 #define hpet_rtc_dropped_irq()			0
+#define hpet_register_irq_handler(h)		0
+#define hpet_unregister_irq_handler(h)		0
 #ifdef RTC_IRQ
 static irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
 {
@@ -1027,7 +1029,15 @@ no_irq:
 
 #ifdef RTC_IRQ
 	if (is_hpet_enabled()) {
+		int err;
+
 		rtc_int_handler_ptr = hpet_rtc_interrupt;
+		err = hpet_register_irq_handler(rtc_interrupt);
+		if (err != 0) {
+			printk(KERN_WARNING "hpet_register_irq_handler failed "
+					"in rtc_init().");
+			return err;
+		}
 	} else {
 		rtc_int_handler_ptr = rtc_interrupt;
 	}
@@ -1050,6 +1060,7 @@ no_irq:
 	if (misc_register(&rtc_dev)) {
 #ifdef RTC_IRQ
 		free_irq(RTC_IRQ, NULL);
+		hpet_unregister_irq_handler(rtc_interrupt);
 		rtc_has_irq = 0;
 #endif
 		rtc_release_region();
@@ -1141,8 +1152,10 @@ static void __exit rtc_exit(void)
 #else
 	rtc_release_region();
 #ifdef RTC_IRQ
-	if (rtc_has_irq)
+	if (rtc_has_irq) {
 		free_irq(RTC_IRQ, NULL);
+		hpet_unregister_irq_handler(hpet_rtc_interrupt);
+	}
 #endif
 #endif /* CONFIG_SPARC32 */
 }

[patch 3/3] Add HPET RTC emulation to RTC_DRV_CMOS

[Bernhard Walle]

[-- Attachment #1: hpet-rtc-cmos --]
[-- Type: text/plain, Size: 6014 bytes --]

That patch adds the RTC emulation of the HPET timer to the new RTC_DRV_CMOS.
The old drivers/char/rtc.ko driver had that functionality and it's important
on new systems.


Signed-off-by: Bernhard Walle <bwalle@suse.de>

---
 arch/x86/Kconfig       |    2 -
 drivers/rtc/rtc-cmos.c |   79 ++++++++++++++++++++++++++++++++++++++++---------
 2 files changed, 67 insertions(+), 14 deletions(-)

--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -405,7 +405,7 @@ config HPET_TIMER
 
 config HPET_EMULATE_RTC
 	def_bool y
-	depends on HPET_TIMER && (RTC=y || RTC=m)
+	depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
 
 # Mark as embedded because too many people got it wrong.
 # The code disables itself when not needed.
--- a/drivers/rtc/rtc-cmos.c
+++ b/drivers/rtc/rtc-cmos.c
@@ -35,10 +35,22 @@
 #include <linux/spinlock.h>
 #include <linux/platform_device.h>
 #include <linux/mod_devicetable.h>
+#include <asm/hpet.h>
 
 /* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */
 #include <asm-generic/rtc.h>
 
+#ifndef CONFIG_HPET_EMULATE_RTC
+#define is_hpet_enabled()			0
+#define hpet_set_alarm_time(hrs, min, sec) 	do { } while (0)
+#define hpet_set_periodic_freq(arg) 		0
+#define hpet_mask_rtc_irq_bit(arg) 		do { } while (0)
+#define hpet_set_rtc_irq_bit(arg) 		do { } while (0)
+#define hpet_rtc_timer_init() 			do { } while (0)
+#define hpet_register_irq_handler(h) 		0
+#define hpet_unregister_irq_handler(h)		do { } while (0)
+extern irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id);
+#endif
 
 struct cmos_rtc {
 	struct rtc_device	*rtc;
@@ -199,6 +211,7 @@ static int cmos_set_alarm(struct device 
 	sec = t->time.tm_sec;
 	sec = (sec < 60) ? BIN2BCD(sec) : 0xff;
 
+	hpet_set_alarm_time(t->time.tm_hour, t->time.tm_min, t->time.tm_sec);
 	spin_lock_irq(&rtc_lock);
 
 	/* next rtc irq must not be from previous alarm setting */
@@ -252,7 +265,8 @@ static int cmos_irq_set_freq(struct devi
 	f = 16 - f;
 
 	spin_lock_irqsave(&rtc_lock, flags);
-	CMOS_WRITE(RTC_REF_CLCK_32KHZ | f, RTC_FREQ_SELECT);
+	if (!hpet_set_periodic_freq(freq))
+		CMOS_WRITE(RTC_REF_CLCK_32KHZ | f, RTC_FREQ_SELECT);
 	spin_unlock_irqrestore(&rtc_lock, flags);
 
 	return 0;
@@ -314,28 +328,37 @@ cmos_rtc_ioctl(struct device *dev, unsig
 	switch (cmd) {
 	case RTC_AIE_OFF:	/* alarm off */
 		rtc_control &= ~RTC_AIE;
+		hpet_mask_rtc_irq_bit(RTC_AIE);
 		break;
 	case RTC_AIE_ON:	/* alarm on */
 		rtc_control |= RTC_AIE;
+		hpet_set_rtc_irq_bit(RTC_AIE);
 		break;
 	case RTC_UIE_OFF:	/* update off */
 		rtc_control &= ~RTC_UIE;
+		hpet_mask_rtc_irq_bit(RTC_UIE);
 		break;
 	case RTC_UIE_ON:	/* update on */
 		rtc_control |= RTC_UIE;
+		hpet_set_rtc_irq_bit(RTC_UIE);
 		break;
 	case RTC_PIE_OFF:	/* periodic off */
 		rtc_control &= ~RTC_PIE;
+		hpet_mask_rtc_irq_bit(RTC_PIE);
 		break;
 	case RTC_PIE_ON:	/* periodic on */
 		rtc_control |= RTC_PIE;
+		hpet_set_rtc_irq_bit(RTC_PIE);
 		break;
 	}
-	CMOS_WRITE(rtc_control, RTC_CONTROL);
+	if (!is_hpet_enabled())
+		CMOS_WRITE(rtc_control, RTC_CONTROL);
+
 	rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
 	rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
 	if (is_intr(rtc_intr))
 		rtc_update_irq(cmos->rtc, 1, rtc_intr);
+
 	spin_unlock_irqrestore(&rtc_lock, flags);
 	return 0;
 }
@@ -475,15 +498,25 @@ static irqreturn_t cmos_interrupt(int ir
 	u8		rtc_control;
 
 	spin_lock(&rtc_lock);
-	irqstat = CMOS_READ(RTC_INTR_FLAGS);
-	rtc_control = CMOS_READ(RTC_CONTROL);
-	irqstat &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
+	/*
+	 * In this case it is HPET RTC interrupt handler
+	 * calling us, with the interrupt information
+	 * passed as arg1, instead of irq.
+	 */
+	if (is_hpet_enabled())
+		irqstat = (unsigned long)irq & 0xF0;
+	else {
+		irqstat = CMOS_READ(RTC_INTR_FLAGS);
+		rtc_control = CMOS_READ(RTC_CONTROL);
+		irqstat &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
+	}
 
 	/* All Linux RTC alarms should be treated as if they were oneshot.
 	 * Similar code may be needed in system wakeup paths, in case the
 	 * alarm woke the system.
 	 */
 	if (irqstat & RTC_AIE) {
+		rtc_control = CMOS_READ(RTC_CONTROL);
 		rtc_control &= ~RTC_AIE;
 		CMOS_WRITE(rtc_control, RTC_CONTROL);
 		CMOS_READ(RTC_INTR_FLAGS);
@@ -591,8 +624,9 @@ cmos_do_probe(struct device *dev, struct
 	 * doesn't use 32KHz here ... for portability we might need to
 	 * do something about other clock frequencies.
 	 */
-	CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);
 	cmos_rtc.rtc->irq_freq = 1024;
+	if (!hpet_set_periodic_freq(cmos_rtc.rtc->irq_freq))
+		CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);
 
 	/* disable irqs.
 	 *
@@ -615,14 +649,31 @@ cmos_do_probe(struct device *dev, struct
 		goto cleanup1;
 	}
 
-	if (is_valid_irq(rtc_irq))
-		retval = request_irq(rtc_irq, cmos_interrupt, IRQF_DISABLED,
-				cmos_rtc.rtc->dev.bus_id,
+	if (is_valid_irq(rtc_irq)) {
+		irq_handler_t rtc_cmos_int_handler;
+
+		if (is_hpet_enabled()) {
+			int err;
+
+			rtc_cmos_int_handler = hpet_rtc_interrupt;
+			err = hpet_register_irq_handler(cmos_interrupt);
+			if (err != 0) {
+				printk(KERN_WARNING "hpet_register_irq_handler "
+						" failed in rtc_init().");
+				goto cleanup1;
+			}
+		} else
+			rtc_cmos_int_handler = cmos_interrupt;
+
+		retval = request_irq(rtc_irq, rtc_cmos_int_handler,
+				IRQF_DISABLED, cmos_rtc.rtc->dev.bus_id,
 				cmos_rtc.rtc);
-	if (retval < 0) {
-		dev_dbg(dev, "IRQ %d is already in use\n", rtc_irq);
-		goto cleanup1;
+		if (retval < 0) {
+			dev_dbg(dev, "IRQ %d is already in use\n", rtc_irq);
+			goto cleanup1;
+		}
 	}
+	hpet_rtc_timer_init();
 
 	/* export at least the first block of NVRAM */
 	nvram.size = address_space - NVRAM_OFFSET;
@@ -677,8 +728,10 @@ static void __exit cmos_do_remove(struct
 
 	sysfs_remove_bin_file(&dev->kobj, &nvram);
 
-	if (is_valid_irq(cmos->irq))
+	if (is_valid_irq(cmos->irq)) {
 		free_irq(cmos->irq, cmos->rtc);
+		hpet_unregister_irq_handler(cmos_interrupt);
+	}
 
 	rtc_device_unregister(cmos->rtc);
 	cmos->rtc = NULL;