Clock management

Collaboration diagram for Clock management:

Data Structures
struct	clk_lock_t

Macros
#define	CLK_PERSISTENT(x)   ((enum clk_level_t) ((x) | 0x80))
#define	CLK_LOCK_INIT(l, clk)
#define	CLK_LOCK(clk)   clk_lock(&clk)
#define	CLK_UNLOCK(clk)   clk_unlock(&clk)
#define	CLK_AUTO_LOCK(l)
#define	DECLARE_CLK_LOCK(l, clk)   static struct clk_lock_t clk = CLK_LOCK_INIT(l, clk)

Enumerations

Functions
void	clk_init (void)
void	clk_relax (void)
void	clk_lock (struct clk_lock_t *clk)
void	clk_unlock (struct clk_lock_t *clk)

Detailed Description

EVE clock management framework.

Macro Definition Documentation

#define CLK_PERSISTENT

(

x

)

((enum clk_level_t) ((x) | 0x80))

Indicates that the given clock should be kept running when system is in the suspend state.

The modifier can be applied to level field of the clk_lock_t instantiation to indicate that the clock should not be switched off at system suspend.

Usage:

struct clk_lock_t MyPersistentClockLock = CLK_LOCK_INIT(CLK_PERSISTENT(CLK_LEVEL_XO), MyPersistentClockLock);

Parameters

x	The actual clock level, clk_level_t.

Definition at line 66 of file clk.h.

#define CLK_LOCK_INIT	(		l,
			clk
	)

Value:

{                                   \
      .link = DLIST_INIT(clk.link),     \
      .level = l,                       \
      .locked = 0,                      \
    }

Initializes a clock lock structure.

The macro is used to initialize a clock lock structure instance.

Parameters

l	clock level
clk	clock lock structure

Usage:

struct clk_lock_t MyXOClockLock = CLK_LOCK_INIT(CLK_LEVEL_XO, MyXOClockLock);

Definition at line 188 of file clk.h.

#define CLK_LOCK

(

clk

)

clk_lock(&clk)

Request the clock

The macro is used to request clock at the given clock level.

Parameters

clk	clock lock structure

Usage:

CLK_LOCK(MyXOClockLock);

Definition at line 194 of file clk.h.

#define CLK_UNLOCK

(

clk

)

clk_unlock(&clk)

Release the clock

The macro is used to release clock at the given clock level.

The clock actually continues to run after the last lock is released until clk_relax() is called explicitly or by pm_relax().

Parameters

clk	clock lock structure

Usage:

CLK_UNLOCK(MyXOClockLock);

Definition at line 195 of file clk.h.

#define CLK_AUTO_LOCK

(

l

)

Value:

struct clk_lock_t EveClkAutoLock __attribute__((cleanup(clk_unlock))); \
      do { EveClkAutoLock = (struct clk_lock_t) CLK_LOCK_INIT(l, EveClkAutoLock); } while (0)

Declares an anonymous auto lock, which holds clock request in the auto variable visibility block

Parameters

l	clock level

Usage:

{
  CLK_AUTO_LOCK(CLK_LEVEL_XO);
  // Do something protected by the lock
}
// The lock is released here

Note: taking in mind lazy nature of releasing the clock locks, use of auto clock locks is negligible.

Definition at line 196 of file clk.h.

#define DECLARE_CLK_LOCK	(		l,
			clk
	)		static struct clk_lock_t clk = CLK_LOCK_INIT(l, clk)

Instantiates a clock lock structure.

The macro is used to instantiate a clock lock structure.

Parameters

l	clock level
clk	clock lock structure

Usage:

DECLARE_CLK_LOCK(CLK_LEVEL_XO, MyXOClockLock);

Definition at line 215 of file clk.h.

Enumeration Type Documentation

enum clk_level_t

Clock level.

The system can use one two high frequency clock sources: a 64 MHz internal oscillator (RC) or a 32 MHz crystal oscillator (XO). The crystal oscillator typically gives better stability, but drains more power from battery.

Clock level is an abstraction for the clock source the system is running on.

Enumerator
CLK_LEVEL_MIN	Minimal possible clock level.
CLK_LEVEL_RC	System uses 64 MHz internal oscillator as a clock source.
CLK_LEVEL_XO	System uses 32 MHz crystal oscillator as a clock source.
CLK_LEVEL__COUNT	Number of elements in the clk_level_t enum.

Definition at line 78 of file clk.h.

Function Documentation

void clk_init

(

void

)

Initializes the clock management framework.

void clk_relax

(

void

)

Switches off released clocks and enters the lowest allowed clock level.

void clk_lock

(

struct clk_lock_t *

clk

)

Requests the clock.

Parameters

clk	pointer to the clock lock structure

void clk_unlock

(

struct clk_lock_t *

clk

)

Releases the clock.

Parameters

clk	pointer to the clock lock structure