UM0851 datasheet(227/245 Pages) STMICROELECTRONICS

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UM0851

Power management section

Doc ID 16604 Rev 2

227/245

The call back functions defined in the structure above are:

●

spear_round_to_table_rate():

This function looks for the rate equal to or less than the target requested rate and

returns the rate to the middle management layer.

●

spear_select_table_rate():

This function configures the rate based on the target requested rate. The clock rate is

strictly monitored to be in the range of frequencies that have been defined in the arch

code i.e. 166 MHz, 266 MHz, 333 MHz.

After the checks, the PLL-1 is reconfigured for the desired frequency value. The new

frequency is then iterated through the clock dependency tree, and all the drivers get to

know the information either by voluntarily calling the clk_get_rate() functions in the

clock framework before making any transactions or plugging into the notifier lists of the

CPUfreq framework. The concept of notifier list has been covered later in Section 10.3:

Power management API

10.3

Power management API

This section describes the PM interfaces.

10.3.1

PM framework API

Figure 67.

Linux PM framework

Valid

Prepare

Enter

Finish

Linux PM framework (kernel/power/pm.c)

Architecture code provides states (arch/arm/mach-spearxxx/pm.c)

UM0851 Datasheet(PDF) 227 Page - STMicroelectronics