/*
*
* Copyright (C) 2001 MontaVista Software, ppopov@mvista.com
* Copied and modified Carsten Langgaard's time.c
*
* Carsten Langgaard, carstenl@mips.com
* Copyright (C) 1999,2000 MIPS Technologies, Inc. All rights reserved.
*
* ########################################################################
*
* This program is free software; you can distribute it and/or modify it
* under the terms of the GNU General Public License (Version 2) as
* published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
*
* ########################################################################
*
* Setting up the clock on the MIPS boards.
*
* Update. Always configure the kernel with CONFIG_NEW_TIME_C. This
* will use the user interface gettimeofday() functions from the
* arch/mips/kernel/time.c, and we provide the clock interrupt processing
* and the timer offset compute functions. If CONFIG_PM is selected,
* we also ensure the 32KHz timer is available. -- Dan
*/
#include <linux/types.h>
#include <linux/init.h>
#include <linux/kernel_stat.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/hardirq.h>
#include <asm/compiler.h>
#include <asm/mipsregs.h>
#include <asm/ptrace.h>
#include <asm/time.h>
#include <asm/div64.h>
#include <asm/mach-au1x00/au1000.h>
#include <linux/mc146818rtc.h>
#include <linux/timex.h>
static unsigned long r4k_offset; /* Amount to increment compare reg each time */
static unsigned long r4k_cur; /* What counter should be at next timer irq */
int no_au1xxx_32khz;
extern int allow_au1k_wait; /* default off for CP0 Counter */
/* Cycle counter value at the previous timer interrupt.. */
static unsigned int timerhi = 0, timerlo = 0;
#ifdef CONFIG_PM
#if HZ < 100 || HZ > 1000
#error "unsupported HZ value! Must be in [100,1000]"
#endif
#define MATCH20_INC (328*100/HZ) /* magic number 328 is for HZ=100... */
extern void startup_match20_interrupt(irqreturn_t (*handler)(int, void *, struct pt_regs *));
static unsigned long last_pc0, last_match20;
#endif
static DEFINE_SPINLOCK(time_lock);
static inline void ack_r4ktimer(unsigned long newval)
{
write_c0_compare(newval);
}
/*
* There are a lot of conceptually broken versions of the MIPS timer interrupt
* handler floating around. This one is rather different, but the algorithm
* is provably more robust.
*/
unsigned long wtimer;
void mips_timer_interrupt(struct pt_regs *regs)
{
int irq = 63;
unsigned long count;
irq_enter();
kstat_this_cpu.irqs[irq]++;
if (r4k_offset == 0)
goto null;
do {
count = read_c0_count();
timerhi += (count < timerlo); /* Wrap around */
timerlo = count;
kstat_this_cpu.irqs[irq]++;
do_timer(regs);
#ifndef CONFIG_SMP
update_process_times(user_mode(regs));
#endif
r4k_cur += r4k_offset;
ack_r4ktimer(r4k_cur);
} while (((unsigned long)read_c0_count()
- r4k_cur) < 0x7fffffff);
irq_exit();
return;
null:
ack_r4ktimer(0);
irq_exit();
}
#ifdef CONFIG_PM
irqreturn_t counter0_irq(int irq, void *dev_id, struct pt_regs *regs)
{
unsigned long pc0;
int time_elapsed;
static int jiffie_drift = 0;
if (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_M20) {
/* should never happen! */
printk(KERN_WARNING "counter 0 w status error\n");
return IRQ_NONE;
}
pc0 = au_readl(SYS_TOYREAD);
if (pc0 < last_match20) {
/* counter overflowed */
time_elapsed = (0xffffffff - last_match20) + pc0;
}
else {
time_elapsed = pc0 - last_match20;
}
while (time_elapsed > 0) {
do_timer(regs);
#ifndef CONFIG_SMP
update_process_times(user_mode(regs));
#endif
time_elapsed -= MATCH20_INC;
last_match20 += MATCH20_INC;
jiffie_drift++;
}
last_pc0 = pc0;
au_writel(last_match20 + MATCH20_INC, SYS_TOYMATCH2);
au_sync();
/* our counter ticks at 10.009765625 ms/tick, we we're running
* almost 10uS too slow per tick.
*/
if (jiffie_drift >= 999) {
jiffie_drift -= 999;
do_timer(regs); /* increment jiffies by one */
#ifndef CONFIG_SMP
update_process_times(user_mode(regs));
#endif
}
return IRQ_HANDLED;
}
/* When we wakeup from sleep, we have to "catch up" on all of the
* timer ticks we have missed.
*/
void
wakeup_counter0_adjust(void)
{
unsigned long pc0;
int time_elapsed;
pc0 = au_readl(SYS_TOYREAD);
if (pc0 < last_match20) {
/* counter overflowed */
time_elapsed = (0xffffffff - last_match20) + pc0;
}
else {
time_elapsed = pc0 - last_match20;
}
while (time_elapsed > 0) {
time_elapsed -= MATCH20_INC;
last_match20 += MATCH20_INC;
}
last_pc0 = pc0;
au_writel(last_match20 + MATCH20_INC, SYS_TOYMATCH2);
au_sync();
}
/* This is just for debugging to set the timer for a sleep delay.
*/
void
wakeup_counter0_set(int ticks)
{
unsigned long pc0;
pc0 = au_readl(SYS_TOYREAD);
last_pc0 = pc0;
au_writel(last_match20 + (MATCH20_INC * ticks), SYS_TOYMATCH2);
au_sync();
}
#endif
/* I haven't found anyone that doesn't use a 12 MHz source clock,
* but just in case.....
*/
#ifdef CONFIG_AU1000_SRC_CLK
#define AU1000_SRC_CLK CONFIG_AU1000_SRC_CLK
#else
#define AU1000_SRC_CLK 12000000
#endif
/*
* We read the real processor speed from the PLL. This is important
* because it is more accurate than computing it from the 32KHz
* counter, if it exists. If we don't have an accurate processor
* speed, all of the peripherals that derive their clocks based on
* this advertised speed will introduce error and sometimes not work
* properly. This function is futher convoluted to still allow configurations
* to do that in case they have really, really old silicon with a
* write-only PLL register, that we need the 32KHz when power management
* "wait" is enabled, and we need to detect if the 32KHz isn't present
* but requested......got it? :-) -- Dan
*/
unsigned long cal_r4koff(void)
{
unsigned long count;
unsigned long cpu_speed;
unsigned long flags;
unsigned long counter;
spin_lock_irqsave(&time_lock, flags);
/* Power management cares if we don't have a 32KHz counter.
*/
no_au1xxx_32khz = 0;
counter = au_readl(SYS_COUNTER_CNTRL);
if (counter & SYS_CNTRL_E0) {
int trim_divide = 16;
au_writel(counter | SYS_CNTRL_EN1, SYS_COUNTER_CNTRL);
while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_T1S);
/* RTC now ticks at 32.768/16 kHz */
au_writel(trim_divide-1, SYS_RTCTRIM);
while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_T1S);
while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C1S);
au_writel (0, SYS_TOYWRITE);
while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C1S);
#if defined(CONFIG_AU1000_USE32K)
{
unsigned long start, end;
start = au_readl(SYS_RTCREAD);
start += 2;
/* wait for the beginning of a new tick
*/
while (au_readl(SYS_RTCREAD) < start);
/* Start r4k counter.
*/
write_c0_count(0);
/* Wait 0.5 seconds.
*/
end = start + (32768 / trim_divide)/2;
while (end > au_readl(SYS_RTCREAD));
count = read_c0_count();
cpu_speed = count * 2;
}
#else
cpu_speed = (au_readl(SYS_CPUPLL) & 0x0000003f) *
AU1000_SRC_CLK;
count = cpu_speed / 2;
#endif
}
else {
/* The 32KHz oscillator isn't running, so assume there
* isn't one and grab the processor speed from the PLL.
* NOTE: some old silicon doesn't allow reading the PLL.
*/
cpu_speed = (au_readl(SYS_CPUPLL) & 0x0000003f) * AU1000_SRC_CLK;
count = cpu_speed / 2;
no_au1xxx_32khz = 1;
}
mips_hpt_frequency = count;
// Equation: Baudrate = CPU / (SD * 2 * CLKDIV * 16)
set_au1x00_uart_baud_base(cpu_speed / (2 * ((int)(au_readl(SYS_POWERCTRL)&0x03) + 2) * 16));
spin_unlock_irqrestore(&time_lock, flags);
return (cpu_speed / HZ);
}
/* This is for machines which generate the exact clock. */
#define USECS_PER_JIFFY (1000000/HZ)
#define USECS_PER_JIFFY_FRAC (0x100000000LL*1000000/HZ&0xffffffff)
static unsigned long
div64_32(unsigned long v1, unsigned long v2, unsigned long v3)
{
unsigned long r0;
do_div64_32(r0, v1, v2, v3);
return r0;
}
static unsigned long do_fast_cp0_gettimeoffset(void)
{
u32 count;
unsigned long res, tmp;
unsigned long r0;
/* Last jiffy when do_fast_gettimeoffset() was called. */
static unsigned long last_jiffies=0;
unsigned long quotient;
/*
* Cached "1/(clocks per usec)*2^32" value.
* It has to be recalculated once each jiffy.
*/
static unsigned long cached_quotient=0;
tmp = jiffies;
quotient = cached_quotient;
if (tmp && last_jiffies != tmp) {
last_jiffies = tmp;
if (last_jiffies != 0) {
r0 = div64_32(timerhi, timerlo, tmp);
quotient = div64_32(USECS_PER_JIFFY, USECS_PER_JIFFY_FRAC, r0);
cached_quotient = quotient;
}
}
/* Get last timer tick in absolute kernel time */
count = read_c0_count();
/* .. relative to previous jiffy (32 bits is enough) */
count -= timerlo;
__asm__("multu\t%1,%2\n\t"
"mfhi\t%0"
: "=r" (res)
: "r" (count), "r" (quotient)
: "hi", "lo", GCC_REG_ACCUM);
/*
* Due to possible jiffies inconsistencies, we need to check
* the result so that we'll get a timer that is monotonic.
*/
if (res >= USECS_PER_JIFFY)
res = USECS_PER_JIFFY-1;
return res;
}
#ifdef CONFIG_PM
static unsigned long do_fast_pm_gettimeoffset(void)
{
unsigned long pc0;
unsigned long offset;
pc0 = au_readl(SYS_TOYREAD);
au_sync();
offset = pc0 - last_pc0;
if (offset > 2*MATCH20_INC) {
printk("huge offset %x, last_pc0 %x last_match20 %x pc0 %x\n",
(unsigned)offset, (unsigned)last_pc0,
(unsigned)last_match20, (unsigned)pc0);
}
offset = (unsigned long)((offset * 305) / 10);
return offset;
}
#endif
void __init au1xxx_timer_setup(struct irqaction *irq)
{
unsigned int est_freq;
printk("calculating r4koff... ");
r4k_offset = cal_r4koff();
printk("%08lx(%d)\n", r4k_offset, (int) r4k_offset);
//est_freq = 2*r4k_offset*HZ;
est_freq = r4k_offset*HZ;
est_freq += 5000; /* round */
est_freq -= est_freq%10000;
printk("CPU frequency %d.%02d MHz\n", est_freq/1000000,
(est_freq%1000000)*100/1000000);
set_au1x00_speed(est_freq);
set_au1x00_lcd_clock(); // program the LCD clock
r4k_cur = (read_c0_count() + r4k_offset);
write_c0_compare(r4k_cur);
#ifdef CONFIG_PM
/*
* setup counter 0, since it keeps ticking after a
* 'wait' instruction has been executed. The CP0 timer and
* counter 1 do NOT continue running after 'wait'
*
* It's too early to call request_irq() here, so we handle
* counter 0 interrupt as a special irq and it doesn't show
* up under /proc/interrupts.
*
* Check to ensure we really have a 32KHz oscillator before
* we do this.
*/
if (no_au1xxx_32khz) {
unsigned int c0_status;
printk("WARNING: no 32KHz clock found.\n");
do_gettimeoffset = do_fast_cp0_gettimeoffset;
/* Ensure we get CPO_COUNTER interrupts.
*/
c0_status = read_c0_status();
c0_status |= IE_IRQ5;
write_c0_status(c0_status);
}
else {
while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C0S);
au_writel(0, SYS_TOYWRITE);
while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C0S);
au_writel(au_readl(SYS_WAKEMSK) | (1<<8), SYS_WAKEMSK);
au_writel(~0, SYS_WAKESRC);
au_sync();
while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_M20);
/* setup match20 to interrupt once every HZ */
last_pc0 = last_match20 = au_readl(SYS_TOYREAD);
au_writel(last_match20 + MATCH20_INC, SYS_TOYMATCH2);
au_sync();
while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_M20);
startup_match20_interrupt(counter0_irq);
do_gettimeoffset = do_fast_pm_gettimeoffset;
/* We can use the real 'wait' instruction.
*/
allow_au1k_wait = 1;
}
#else
/* We have to do this here instead of in timer_init because
* the generic code in arch/mips/kernel/time.c will write
* over our function pointer.
*/
do_gettimeoffset = do_fast_cp0_gettimeoffset;
#endif
}
void __init au1xxx_time_init(void)
{
}
