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// ------------------------------------------------------------
// Cortex-A MPCore - Private timer functions
//
// Copyright ARM Ltd 2009. All rights reserved.
// ------------------------------------------------------------
.text
.align 4
// PPI ID 29
// Typical set of calls to enable Timer:
// init_private_timer(0xXXXX, 0) <-- Counter down value of 0xXXXX, with auto-reload
// start_private_timer()
// Timer offset from base of private peripheral space --> 0x600
// ------------------------------------------------------------
.global init_private_timer
.type init_private_timer,function
// void init_private_timer(unsigned int load_value, unsigned int auto_reload)
// Sets up the private timer
// r0: initial load value
// r1: IF 0 (AutoReload) ELSE (SingleShot)
init_private_timer:
// Get base address of private perpherial space
MOV r2, r0 // Make a copy of r0 before corrupting
MRC p15, 4, r0, c15, c0, 0 // Read periph base address
// Set the load value
STR r2, [r0, #0x600]
// Control register bit layout
// Bit 0 - Enable
// Bit 1 - Auto-Reload // see DE681117
// Bit 2 - IRQ Generation
// Form control reg value
CMP r1, #0 // Check whether to enable auto-reload
MOVNE r2, #0x04 // No auto-reload
MOVEQ r2, #0x06 // With auto-reload
// Store to control register
STR r2, [r0, #0x608]
BX lr
// ------------------------------------------------------------
// void start_private_timer(void)
// Starts the private timer
.global start_private_timer
.type start_private_timer,function
start_private_timer:
MRC p15, 4, r0, c15, c0, 0 // Read periph base address
LDR r1, [r0, #0x608] // Read control reg
ORR r1, r1, #0x01 // Set enable bit
STR r1, [r0, #0x608] // Write modified value back
BX lr
// ------------------------------------------------------------
// void stop_private_timer(void)
// Stops the private timer
.global stop_private_timer
.type stop_private_timer,function
stop_private_timer:
MRC p15, 4, r0, c15, c0, 0 // Read periph base address
LDR r1, [r0, #0x608] // Read control reg
BIC r1, r1, #0x01 // Clear enable bit
STR r1, [r0, #0x608] // Write modified value back
BX lr
// ------------------------------------------------------------
// unsigned int read_private_timer(void)
// Reads the current value of the timer count register
.global get_private_timer_count
.type get_private_timer_count,function
get_private_timer_count:
MRC p15, 4, r0, c15, c0, 0 // Read periph base address
LDR r0, [r0, #0x604] // Read count register
BX lr
// ------------------------------------------------------------
// void clear_private_timer_irq(void)
// Clears the private timer interrupt
.global clear_private_timer_irq
.type clear_private_timer_irq,function
clear_private_timer_irq:
MRC p15, 4, r0, c15, c0, 0 // Read periph base address
// Clear the interrupt by writing 0x1 to the Timer's Interrupt Status register
MOV r1, #1
STR r1, [r0, #0x60C]
BX lr
// ------------------------------------------------------------
// End of code
// ------------------------------------------------------------
// ------------------------------------------------------------
// End of MP_PrivateTimer.s
// ------------------------------------------------------------
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