[RFC/RFT][PATCH -mm 3/8] ACPI: Add acpi_pm_device_sleep_state helper routine (updated)

Rafael J. Wysocki
2007-06-26T09:53:29Z

[The previous version wouldn't work correctly.]
---
From: Shaohua Li <shaohua.li@intel.com>, Rafael J. Wysocki <rjw@sisk.pl>

Based on the David Brownell's patch at
http://marc.info/?l=linux-acpi&m=117873972806360&w=2

Add a helper routine returning the lowest power (highest number) ACPI device
power state that given device can be in while the system is in the sleep state
indicated by acpi_target_sleep_state .

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
drivers/acpi/sleep/main.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++
include/acpi/acpi_bus.h | 2 +
2 files changed, 53 insertions(+)

Index: linux-2.6.22-rc6/drivers/acpi/sleep/main.c
===================================================================
--- linux-2.6.22-rc6.orig/drivers/acpi/sleep/main.c
+++ linux-2.6.22-rc6/drivers/acpi/sleep/main.c
@@ -262,6 +262,57 @@ static struct hibernation_ops acpi_hiber
};
#endif /* CONFIG_SOFTWARE_SUSPEND */

+/**
+ * acpi_pm_device_sleep_state - return the lowest power (highest number)
+ * ACPI device power state given device can be
+ * in while the system is in the sleep state
+ * indicated by %acpi_target_sleep_state
+ * @handle: Represents the device the state is evaluated for
+ */
+
+int acpi_pm_device_sleep_state(acpi_handle handle)
+{
+ char acpi_method[] = "_SxD";
+ unsigned long d_min, d_max;
+ struct acpi_device *dev;
+
+ if (!handle || ACPI_FAILURE(acpi_bus_get_device(handle, &adev)))
+ printk(KERN_ERR "ACPI handle has no context!\n");
+ return -ENODEV;
+ }
+ acpi_method[2] = '0' + acpi_target_sleep_state;
+ /*
+ * If the sleep state is S0, we will return D3, but if the device has
+ * _S0W, we will use the value from _S0W
+ */
+ d_min = ACPI_STATE_D3;
+ d_max = ACPI_STATE_D3;
+ /*
+ * If present, _SxD methods give the minimum D-state we may use
+ * for each S-state ... with lowest latency state switching.
+ *
+ * We rely on acpi_evaluate_integer() not clobbering the integer
+ * provided -- that's our fault recovery, we ignore retval.
+ */
+ if (acpi_target_sleep_state > ACPI_STATE_S0)
+ acpi_evaluate_integer(handle, acpi_method, NULL, &d_min);
+
+ /*
+ * If _PRW says we can wake from the upcoming system state, the _SxD
+ * value can wake ... and we'll assume a wakeup-aware driver. If _SxW
+ * methods exist (ACPI 3.x), they give the lowest power D-state that
+ * can also wake the system. _S0W can be valid.
+ */
+ if (acpi_target_sleep_state == ACPI_STATE_S0 ||
+ (dev->wakeup.state.enabled &&
+ dev->wakeup.sleep_state <= acpi_target_sleep_state)) {
+ d_max = d_min;
+ acpi_method[3] = 'W';
+ acpi_evaluate_integer(handle, acpi_method, NULL, &d_max);
+ }
+ return d_max;
+}
+
/*
* Toshiba fails to preserve interrupts over S1, reinitialization
* of 8259 is needed after S1 resume.
Index: linux-2.6.22-rc6/include/acpi/acpi_bus.h
===================================================================
--- linux-2.6.22-rc6.orig/include/acpi/acpi_bus.h
+++ linux-2.6.22-rc6/include/acpi/acpi_bus.h
@@ -364,6 +364,8 @@ acpi_handle acpi_get_child(acpi_handle,
acpi_handle acpi_get_pci_rootbridge_handle(unsigned int, unsigned int);
#define DEVICE_ACPI_HANDLE(dev) ((acpi_handle)((dev)->archdata.acpi_handle))

+int acpi_pm_device_sleep_state(acpi_handle handle);
+
#endif /* CONFIG_ACPI */

#endif /*__ACPI_BUS_H__*/