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ARM: ep93xx: move timer to its own file
This breaks the timer code out of the core file in preparation for refactoring. Tested-by: H Hartley Sweeten <hsweeten@visionengravers.com> Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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Linus Walleij
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,112 @@ | ||
| #include <linux/kernel.h> | ||
| #include <linux/init.h> | ||
| #include <linux/interrupt.h> | ||
| #include <linux/irq.h> | ||
| #include <linux/io.h> | ||
| #include <asm/mach/time.h> | ||
| #include "soc.h" | ||
|
|
||
| /************************************************************************* | ||
| * Timer handling for EP93xx | ||
| ************************************************************************* | ||
| * The ep93xx has four internal timers. Timers 1, 2 (both 16 bit) and | ||
| * 3 (32 bit) count down at 508 kHz, are self-reloading, and can generate | ||
| * an interrupt on underflow. Timer 4 (40 bit) counts down at 983.04 kHz, | ||
| * is free-running, and can't generate interrupts. | ||
| * | ||
| * The 508 kHz timers are ideal for use for the timer interrupt, as the | ||
| * most common values of HZ divide 508 kHz nicely. We pick one of the 16 | ||
| * bit timers (timer 1) since we don't need more than 16 bits of reload | ||
| * value as long as HZ >= 8. | ||
| * | ||
| * The higher clock rate of timer 4 makes it a better choice than the | ||
| * other timers for use in gettimeoffset(), while the fact that it can't | ||
| * generate interrupts means we don't have to worry about not being able | ||
| * to use this timer for something else. We also use timer 4 for keeping | ||
| * track of lost jiffies. | ||
| */ | ||
| #define EP93XX_TIMER_REG(x) (EP93XX_TIMER_BASE + (x)) | ||
| #define EP93XX_TIMER1_LOAD EP93XX_TIMER_REG(0x00) | ||
| #define EP93XX_TIMER1_VALUE EP93XX_TIMER_REG(0x04) | ||
| #define EP93XX_TIMER1_CONTROL EP93XX_TIMER_REG(0x08) | ||
| #define EP93XX_TIMER123_CONTROL_ENABLE (1 << 7) | ||
| #define EP93XX_TIMER123_CONTROL_MODE (1 << 6) | ||
| #define EP93XX_TIMER123_CONTROL_CLKSEL (1 << 3) | ||
| #define EP93XX_TIMER1_CLEAR EP93XX_TIMER_REG(0x0c) | ||
| #define EP93XX_TIMER2_LOAD EP93XX_TIMER_REG(0x20) | ||
| #define EP93XX_TIMER2_VALUE EP93XX_TIMER_REG(0x24) | ||
| #define EP93XX_TIMER2_CONTROL EP93XX_TIMER_REG(0x28) | ||
| #define EP93XX_TIMER2_CLEAR EP93XX_TIMER_REG(0x2c) | ||
| #define EP93XX_TIMER4_VALUE_LOW EP93XX_TIMER_REG(0x60) | ||
| #define EP93XX_TIMER4_VALUE_HIGH EP93XX_TIMER_REG(0x64) | ||
| #define EP93XX_TIMER4_VALUE_HIGH_ENABLE (1 << 8) | ||
| #define EP93XX_TIMER3_LOAD EP93XX_TIMER_REG(0x80) | ||
| #define EP93XX_TIMER3_VALUE EP93XX_TIMER_REG(0x84) | ||
| #define EP93XX_TIMER3_CONTROL EP93XX_TIMER_REG(0x88) | ||
| #define EP93XX_TIMER3_CLEAR EP93XX_TIMER_REG(0x8c) | ||
|
|
||
| #define EP93XX_TIMER123_CLOCK 508469 | ||
| #define EP93XX_TIMER4_CLOCK 983040 | ||
|
|
||
| #define TIMER1_RELOAD ((EP93XX_TIMER123_CLOCK / HZ) - 1) | ||
| #define TIMER4_TICKS_PER_JIFFY DIV_ROUND_CLOSEST(EP93XX_TIMER4_CLOCK, HZ) | ||
|
|
||
| static unsigned int last_jiffy_time; | ||
|
|
||
| static irqreturn_t ep93xx_timer_interrupt(int irq, void *dev_id) | ||
| { | ||
| /* Writing any value clears the timer interrupt */ | ||
| __raw_writel(1, EP93XX_TIMER1_CLEAR); | ||
|
|
||
| /* Recover lost jiffies */ | ||
| while ((signed long) | ||
| (__raw_readl(EP93XX_TIMER4_VALUE_LOW) - last_jiffy_time) | ||
| >= TIMER4_TICKS_PER_JIFFY) { | ||
| last_jiffy_time += TIMER4_TICKS_PER_JIFFY; | ||
| timer_tick(); | ||
| } | ||
|
|
||
| return IRQ_HANDLED; | ||
| } | ||
|
|
||
| static struct irqaction ep93xx_timer_irq = { | ||
| .name = "ep93xx timer", | ||
| .flags = IRQF_TIMER | IRQF_IRQPOLL, | ||
| .handler = ep93xx_timer_interrupt, | ||
| }; | ||
|
|
||
| static u32 ep93xx_gettimeoffset(void) | ||
| { | ||
| int offset; | ||
|
|
||
| offset = __raw_readl(EP93XX_TIMER4_VALUE_LOW) - last_jiffy_time; | ||
|
|
||
| /* | ||
| * Timer 4 is based on a 983.04 kHz reference clock, | ||
| * so dividing by 983040 gives the fraction of a second, | ||
| * so dividing by 0.983040 converts to uS. | ||
| * Refactor the calculation to avoid overflow. | ||
| * Finally, multiply by 1000 to give nS. | ||
| */ | ||
| return (offset + (53 * offset / 3072)) * 1000; | ||
| } | ||
|
|
||
| void __init ep93xx_timer_init(void) | ||
| { | ||
| u32 tmode = EP93XX_TIMER123_CONTROL_MODE | | ||
| EP93XX_TIMER123_CONTROL_CLKSEL; | ||
|
|
||
| arch_gettimeoffset = ep93xx_gettimeoffset; | ||
|
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||
| /* Enable periodic HZ timer. */ | ||
| __raw_writel(tmode, EP93XX_TIMER1_CONTROL); | ||
| __raw_writel(TIMER1_RELOAD, EP93XX_TIMER1_LOAD); | ||
| __raw_writel(tmode | EP93XX_TIMER123_CONTROL_ENABLE, | ||
| EP93XX_TIMER1_CONTROL); | ||
|
|
||
| /* Enable lost jiffy timer. */ | ||
| __raw_writel(EP93XX_TIMER4_VALUE_HIGH_ENABLE, | ||
| EP93XX_TIMER4_VALUE_HIGH); | ||
|
|
||
| setup_irq(IRQ_EP93XX_TIMER1, &ep93xx_timer_irq); | ||
| } |