pm_trans_check(9F) Kernel Functions for Drivers pm_trans_check(9F)NAMEpm_trans_check - Device power cycle advisory check
SYNOPSIS
#include <sys/sunddi.h>
int pm_trans_check(struct pm_trans_data *datap, time_t *intervalp);
INTERFACE LEVEL
Solaris DDI specific (Solaris DDI)
PARAMETERS
datap Pointer to a pm_trans_data structure
intervalp Pointer to time difference when next power cycle will be
advised
DESCRIPTION
The pm_trans_check() function checks if a power-cycle is currently
advised based on data in the pm_trans_data structure. This function is
provided to prevent damage to devices from excess power cycles; drivers
for devices that are sensitive to the number of power cycles should
call pm_trans_check() from their power(9E) function before powering-off
a device. If pm_trans_check() indicates that the device should not be
power cycled, the driver should not attempt to power cycle the device
and should fail the call to power(9E) entry point.
If pm_trans_check() returns that it is not advised to power cycle the
device, it attempts to calculate when the next power cycle is advised,
based on the supplied parameters. In such case, intervalp returns the
time difference (in seconds) from the current time to when the next
power cycle is advised. If the time for the next power cycle cannot be
determined, intervalp indicates 0.
To avoid excessive calls to the power(9E) entry point during a period
when power cycling is not advised, the driver should mark the corre‐
sponding device component busy for the intervalp time period (if
interval is not 0). Conveniently, the driver can utilize the fact that
calls to pm_busy_component(9F) are stacked. If power cycling is not
advised, the driver can call pm_busy_component(9F) and issue a time‐
out(9F) for the intervalp time. The timeout() handler can issue the
corresponding pm_idle_component(9F) call.
The format field of pm_trans_data accepts either DC_SCSI_FORMAT or
DC_SMART_FORMAT. If the caller provides information from a SCSI Log
Page, it should set the format field to DC_SCSI_FORMAT, and provide
valid data in svc_date[], lifemax, ncycles and flag in the
pm_scsi_cycles structure. If the caller provides information from a
SMART feature attribute, it should set the format field to
DC_SMART_FORMAT and provide valid data in allowed, usedup and flag in
the pm_smart_count structure, where allowed indicates the normalized
cycle count before reaching the borderline threshold cycle count, and
usedup indicates the normalized consumed cycle count.
The flag field in both pm_scsi_cycles and pm_smart_count structures is
reserved for future use and must be set to 0.
struct pm_trans_data {
int format; /* data format */
union {
struct pm_scsi_cycles scsi_cycles;
struct pm_smart_count smart_count;
} un;
};
RETURN VALUES
1 Power cycle is advised.
0 Power cycle is not advised.
-1 Error due to invalid argument.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Committed │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOpower.conf(4), attributes(5), power(9E)
Writing Device Drivers
Using Power Management
SunOS 5.11 16 Jul 2009 pm_trans_check(9F)