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[PATCH] ARM: Convert ARM timer implementations to use readl/writel
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Convert ARMs timer implementations to use readl/writel instead of accessing
the registers via a struct.

People have recently asked if accessing timers via a structure is the
"right way" and its not the Linux way.  So fix this code to conform to
"The Linux Way"(tm).

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
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Russell King authored and Russell King committed Jun 29, 2005
1 parent 6904b24 commit b720f73
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Showing 3 changed files with 59 additions and 65 deletions.
42 changes: 14 additions & 28 deletions arch/arm/mach-integrator/core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/hardware/amba.h>
#include <asm/hardware/arm_timer.h>
#include <asm/arch/cm.h>
#include <asm/system.h>
#include <asm/leds.h>
Expand Down Expand Up @@ -156,16 +157,6 @@ EXPORT_SYMBOL(cm_control);
#define TICKS2USECS(x) ((x) / TICKS_PER_uSEC)
#endif

/*
* What does it look like?
*/
typedef struct TimerStruct {
unsigned long TimerLoad;
unsigned long TimerValue;
unsigned long TimerControl;
unsigned long TimerClear;
} TimerStruct_t;

static unsigned long timer_reload;

/*
Expand All @@ -174,7 +165,6 @@ static unsigned long timer_reload;
*/
unsigned long integrator_gettimeoffset(void)
{
volatile TimerStruct_t *timer1 = (TimerStruct_t *)TIMER1_VA_BASE;
unsigned long ticks1, ticks2, status;

/*
Expand All @@ -183,11 +173,11 @@ unsigned long integrator_gettimeoffset(void)
* an interrupt. We get around this by ensuring that the
* counter has not reloaded between our two reads.
*/
ticks2 = timer1->TimerValue & 0xffff;
ticks2 = readl(TIMER1_VA_BASE + TIMER_VALUE) & 0xffff;
do {
ticks1 = ticks2;
status = __raw_readl(VA_IC_BASE + IRQ_RAW_STATUS);
ticks2 = timer1->TimerValue & 0xffff;
ticks2 = readl(TIMER1_VA_BASE + TIMER_VALUE) & 0xffff;
} while (ticks2 > ticks1);

/*
Expand All @@ -213,20 +203,19 @@ unsigned long integrator_gettimeoffset(void)
static irqreturn_t
integrator_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
volatile TimerStruct_t *timer1 = (volatile TimerStruct_t *)TIMER1_VA_BASE;

write_seqlock(&xtime_lock);

/*
* clear the interrupt
*/
timer1->TimerClear = 1;
writel(1, TIMER1_VA_BASE + TIMER_INTCLR);

/*
* the clock tick routines are only processed on the
* primary CPU
*/
if (hard_smp_processor_id() == 0) {
nmi_tick();
timer_tick(regs);
#ifdef CONFIG_SMP
smp_send_timer();
Expand Down Expand Up @@ -256,32 +245,29 @@ static struct irqaction integrator_timer_irq = {
*/
void __init integrator_time_init(unsigned long reload, unsigned int ctrl)
{
volatile TimerStruct_t *timer0 = (volatile TimerStruct_t *)TIMER0_VA_BASE;
volatile TimerStruct_t *timer1 = (volatile TimerStruct_t *)TIMER1_VA_BASE;
volatile TimerStruct_t *timer2 = (volatile TimerStruct_t *)TIMER2_VA_BASE;
unsigned int timer_ctrl = 0x80 | 0x40; /* periodic */
unsigned int timer_ctrl = TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC;

timer_reload = reload;
timer_ctrl |= ctrl;

if (timer_reload > 0x100000) {
timer_reload >>= 8;
timer_ctrl |= 0x08; /* /256 */
timer_ctrl |= TIMER_CTRL_DIV256;
} else if (timer_reload > 0x010000) {
timer_reload >>= 4;
timer_ctrl |= 0x04; /* /16 */
timer_ctrl |= TIMER_CTRL_DIV16;
}

/*
* Initialise to a known state (all timers off)
*/
timer0->TimerControl = 0;
timer1->TimerControl = 0;
timer2->TimerControl = 0;
writel(0, TIMER0_VA_BASE + TIMER_CTRL);
writel(0, TIMER1_VA_BASE + TIMER_CTRL);
writel(0, TIMER2_VA_BASE + TIMER_CTRL);

timer1->TimerLoad = timer_reload;
timer1->TimerValue = timer_reload;
timer1->TimerControl = timer_ctrl;
writel(timer_reload, TIMER1_VA_BASE + TIMER_LOAD);
writel(timer_reload, TIMER1_VA_BASE + TIMER_VALUE);
writel(timer_ctrl, TIMER1_VA_BASE + TIMER_CTRL);

/*
* Make irqs happen for the system timer
Expand Down
61 changes: 24 additions & 37 deletions arch/arm/mach-versatile/core.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,7 @@
#include <asm/mach-types.h>
#include <asm/hardware/amba.h>
#include <asm/hardware/amba_clcd.h>
#include <asm/hardware/arm_timer.h>
#include <asm/hardware/icst307.h>

#include <asm/mach/arch.h>
Expand Down Expand Up @@ -788,38 +789,25 @@ void __init versatile_init(void)
*/
#define TIMER_INTERVAL (TICKS_PER_uSEC * mSEC_10)
#if TIMER_INTERVAL >= 0x100000
#define TIMER_RELOAD (TIMER_INTERVAL >> 8) /* Divide by 256 */
#define TIMER_CTRL 0x88 /* Enable, Clock / 256 */
#define TIMER_RELOAD (TIMER_INTERVAL >> 8)
#define TIMER_DIVISOR (TIMER_CTRL_DIV256)
#define TICKS2USECS(x) (256 * (x) / TICKS_PER_uSEC)
#elif TIMER_INTERVAL >= 0x10000
#define TIMER_RELOAD (TIMER_INTERVAL >> 4) /* Divide by 16 */
#define TIMER_CTRL 0x84 /* Enable, Clock / 16 */
#define TIMER_DIVISOR (TIMER_CTRL_DIV16)
#define TICKS2USECS(x) (16 * (x) / TICKS_PER_uSEC)
#else
#define TIMER_RELOAD (TIMER_INTERVAL)
#define TIMER_CTRL 0x80 /* Enable */
#define TIMER_DIVISOR (TIMER_CTRL_DIV1)
#define TICKS2USECS(x) ((x) / TICKS_PER_uSEC)
#endif

#define TIMER_CTRL_IE (1 << 5) /* Interrupt Enable */

/*
* What does it look like?
*/
typedef struct TimerStruct {
unsigned long TimerLoad;
unsigned long TimerValue;
unsigned long TimerControl;
unsigned long TimerClear;
} TimerStruct_t;

/*
* Returns number of ms since last clock interrupt. Note that interrupts
* will have been disabled by do_gettimeoffset()
*/
static unsigned long versatile_gettimeoffset(void)
{
volatile TimerStruct_t *timer0 = (TimerStruct_t *)TIMER0_VA_BASE;
unsigned long ticks1, ticks2, status;

/*
Expand All @@ -828,11 +816,11 @@ static unsigned long versatile_gettimeoffset(void)
* an interrupt. We get around this by ensuring that the
* counter has not reloaded between our two reads.
*/
ticks2 = timer0->TimerValue & 0xffff;
ticks2 = readl(TIMER0_VA_BASE + TIMER_VALUE) & 0xffff;
do {
ticks1 = ticks2;
status = __raw_readl(VA_IC_BASE + VIC_IRQ_RAW_STATUS);
ticks2 = timer0->TimerValue & 0xffff;
ticks2 = readl(TIMER0_VA_BASE + TIMER_VALUE) & 0xffff;
} while (ticks2 > ticks1);

/*
Expand All @@ -859,12 +847,10 @@ static unsigned long versatile_gettimeoffset(void)
*/
static irqreturn_t versatile_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
volatile TimerStruct_t *timer0 = (volatile TimerStruct_t *)TIMER0_VA_BASE;

write_seqlock(&xtime_lock);

// ...clear the interrupt
timer0->TimerClear = 1;
writel(1, TIMER0_VA_BASE + TIMER_INTCLR);

timer_tick(regs);

Expand All @@ -884,31 +870,32 @@ static struct irqaction versatile_timer_irq = {
*/
static void __init versatile_timer_init(void)
{
volatile TimerStruct_t *timer0 = (volatile TimerStruct_t *)TIMER0_VA_BASE;
volatile TimerStruct_t *timer1 = (volatile TimerStruct_t *)TIMER1_VA_BASE;
volatile TimerStruct_t *timer2 = (volatile TimerStruct_t *)TIMER2_VA_BASE;
volatile TimerStruct_t *timer3 = (volatile TimerStruct_t *)TIMER3_VA_BASE;
u32 val;

/*
* set clock frequency:
* VERSATILE_REFCLK is 32KHz
* VERSATILE_TIMCLK is 1MHz
*/
*(volatile unsigned int *)IO_ADDRESS(VERSATILE_SCTL_BASE) |=
((VERSATILE_TIMCLK << VERSATILE_TIMER1_EnSel) | (VERSATILE_TIMCLK << VERSATILE_TIMER2_EnSel) |
(VERSATILE_TIMCLK << VERSATILE_TIMER3_EnSel) | (VERSATILE_TIMCLK << VERSATILE_TIMER4_EnSel));
val = readl(IO_ADDRESS(VERSATILE_SCTL_BASE));
writel((VERSATILE_TIMCLK << VERSATILE_TIMER1_EnSel) |
(VERSATILE_TIMCLK << VERSATILE_TIMER2_EnSel) |
(VERSATILE_TIMCLK << VERSATILE_TIMER3_EnSel) |
(VERSATILE_TIMCLK << VERSATILE_TIMER4_EnSel) | val,
IO_ADDRESS(VERSATILE_SCTL_BASE));

/*
* Initialise to a known state (all timers off)
*/
timer0->TimerControl = 0;
timer1->TimerControl = 0;
timer2->TimerControl = 0;
timer3->TimerControl = 0;

timer0->TimerLoad = TIMER_RELOAD;
timer0->TimerValue = TIMER_RELOAD;
timer0->TimerControl = TIMER_CTRL | 0x40 | TIMER_CTRL_IE; /* periodic + IE */
writel(0, TIMER0_VA_BASE + TIMER_CTRL);
writel(0, TIMER1_VA_BASE + TIMER_CTRL);
writel(0, TIMER2_VA_BASE + TIMER_CTRL);
writel(0, TIMER3_VA_BASE + TIMER_CTRL);

writel(TIMER_RELOAD, TIMER0_VA_BASE + TIMER_LOAD);
writel(TIMER_RELOAD, TIMER0_VA_BASE + TIMER_VALUE);
writel(TIMER_DIVISOR | TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC |
TIMER_CTRL_IE, TIMER0_VA_BASE + TIMER_CTRL);

/*
* Make irqs happen for the system timer
Expand Down
21 changes: 21 additions & 0 deletions include/asm-arm/hardware/arm_timer.h
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Original file line number Diff line number Diff line change
@@ -0,0 +1,21 @@
#ifndef __ASM_ARM_HARDWARE_ARM_TIMER_H
#define __ASM_ARM_HARDWARE_ARM_TIMER_H

#define TIMER_LOAD 0x00
#define TIMER_VALUE 0x04
#define TIMER_CTRL 0x08
#define TIMER_CTRL_ONESHOT (1 << 0)
#define TIMER_CTRL_32BIT (1 << 1)
#define TIMER_CTRL_DIV1 (0 << 2)
#define TIMER_CTRL_DIV16 (1 << 2)
#define TIMER_CTRL_DIV256 (2 << 2)
#define TIMER_CTRL_IE (1 << 5) /* Interrupt Enable (versatile only) */
#define TIMER_CTRL_PERIODIC (1 << 6)
#define TIMER_CTRL_ENABLE (1 << 7)

#define TIMER_INTCLR 0x0c
#define TIMER_RIS 0x10
#define TIMER_MIS 0x14
#define TIMER_BGLOAD 0x18

#endif

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