[PATCH v5 1/2] clocksource: acpi_pm: Add external callback for suspend/resume

[Marek Maslanka <mmaslanka@google.com>]

Provides the capability to register an external callback for the ACPI PM
timer, which is called during the suspend and resume processes.

Signed-off-by: Marek Maslanka <mmaslanka@google.com>

---
Changes in v5:
- Rename acpi_pm_register_suspend_resume_callback to
  acpi_pmtmr_register_suspend_resume_callback and move prototype to
  include/linux/acpi_pmtmr.h
- Remove the acpi_pm.h header added in the previous patch.
- Link to v4: https://lore.kernel.org/lkml/20240809131343.1173369-1-mmaslanka@google.com/
---
---
 drivers/clocksource/acpi_pm.c | 24 ++++++++++++++++++++++++
 include/linux/acpi_pmtmr.h    |  8 ++++++++
 2 files changed, 32 insertions(+)

diff --git a/drivers/clocksource/acpi_pm.c b/drivers/clocksource/acpi_pm.c
index 82338773602ca..fab19b7de55c1 100644
--- a/drivers/clocksource/acpi_pm.c
+++ b/drivers/clocksource/acpi_pm.c
@@ -25,6 +25,10 @@
 #include <asm/io.h>
 #include <asm/time.h>
 
+static void *suspend_resume_cb_data;
+
+static void (*suspend_resume_callback)(void *data, bool suspend);
+
 /*
  * The I/O port the PMTMR resides at.
  * The location is detected during setup_arch(),
@@ -58,6 +62,24 @@ u32 acpi_pm_read_verified(void)
 	return v2;
 }
 
+void acpi_pmtmr_register_suspend_resume_callback(void (*cb)(void *data, bool suspend), void *data)
+{
+	suspend_resume_callback = cb;
+	suspend_resume_cb_data = data;
+}
+
+static void acpi_pm_suspend(struct clocksource *cs)
+{
+	if (suspend_resume_callback)
+		suspend_resume_callback(suspend_resume_cb_data, true);
+}
+
+static void acpi_pm_resume(struct clocksource *cs)
+{
+	if (suspend_resume_callback)
+		suspend_resume_callback(suspend_resume_cb_data, false);
+}
+
 static u64 acpi_pm_read(struct clocksource *cs)
 {
 	return (u64)read_pmtmr();
@@ -69,6 +91,8 @@ static struct clocksource clocksource_acpi_pm = {
 	.read		= acpi_pm_read,
 	.mask		= (u64)ACPI_PM_MASK,
 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
+	.suspend	= acpi_pm_suspend,
+	.resume		= acpi_pm_resume,
 };
 
 
diff --git a/include/linux/acpi_pmtmr.h b/include/linux/acpi_pmtmr.h
index 50d88bf1498d7..a5262d28b97e0 100644
--- a/include/linux/acpi_pmtmr.h
+++ b/include/linux/acpi_pmtmr.h
@@ -26,6 +26,14 @@ static inline u32 acpi_pm_read_early(void)
 	return acpi_pm_read_verified() & ACPI_PM_MASK;
 }
 
+/**
+ * Register callback for suspend and resume event
+ *
+ * @cb Callback triggered on suspend and resume
+ * @data Data passed with the callback
+ */
+void acpi_pmtmr_register_suspend_resume_callback(void (*cb)(void *data, bool suspend), void *data);
+
 #else
 
 static inline u32 acpi_pm_read_early(void)
-- 
2.46.0.76.ge559c4bf1a-goog