arch/arm/mach-pnx4008/time.c

   1 /*
   2  * arch/arm/mach-pnx4008/time.c
   3  *
   4  * PNX4008 Timers
   5  *
   6  * Authors: Vitaly Wool, Dmitry Chigirev, Grigory Tolstolytkin <source@mvista.com>
   7  *
   8  * 2005 (c) MontaVista Software, Inc. This file is licensed under
   9  * the terms of the GNU General Public License version 2. This program
  10  * is licensed "as is" without any warranty of any kind, whether express
  11  * or implied.
  12  */
  13
  14 #include <linux/config.h>
  15 #include <linux/kernel.h>
  16 #include <linux/init.h>
  17 #include <linux/delay.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/sched.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/module.h>
  22 #include <linux/kallsyms.h>
  23 #include <linux/time.h>
  24 #include <linux/timex.h>
  25 #include <linux/irq.h>
  26
  27 #include <asm/system.h>
  28 #include <asm/hardware.h>
  29 #include <asm/io.h>
  30 #include <asm/leds.h>
  31 #include <asm/mach/time.h>
  32 #include <asm/errno.h>
  33
  34 /*! Note: all timers are UPCOUNTING */
  35
  36 /*!
  37  * Returns number of us since last clock interrupt.  Note that interrupts
  38  * will have been disabled by do_gettimeoffset()
  39  */
  40 static unsigned long pnx4008_gettimeoffset(void)
  41 {
  42         u32 ticks_to_match =
  43             __raw_readl(HSTIM_MATCH0) - __raw_readl(HSTIM_COUNTER);
  44         u32 elapsed = LATCH - ticks_to_match;
  45         return (elapsed * (tick_nsec / 1000)) / LATCH;
  46 }
  47
  48 /*!
  49  * IRQ handler for the timer
  50  */
  51 static irqreturn_t pnx4008_timer_interrupt(int irq, void *dev_id,
  52                                            struct pt_regs *regs)
  53 {
  54         if (__raw_readl(HSTIM_INT) & MATCH0_INT) {
  55
  56                 write_seqlock(&xtime_lock);
  57
  58                 do {
  59                         timer_tick(regs);
  60
  61                         /*
  62                          * this algorithm takes care of possible delay
  63                          * for this interrupt handling longer than a normal
  64                          * timer period
  65                          */
  66                         __raw_writel(__raw_readl(HSTIM_MATCH0) + LATCH,
  67                                      HSTIM_MATCH0);
  68                         __raw_writel(MATCH0_INT, HSTIM_INT);    /* clear interrupt */
  69
  70                         /*
  71                          * The goal is to keep incrementing HSTIM_MATCH0
  72                          * register until HSTIM_MATCH0 indicates time after
  73                          * what HSTIM_COUNTER indicates.
  74                          */
  75                 } while ((signed)
  76                          (__raw_readl(HSTIM_MATCH0) -
  77                           __raw_readl(HSTIM_COUNTER)) < 0);
  78
  79                 write_sequnlock(&xtime_lock);
  80         }
  81
  82         return IRQ_HANDLED;
  83 }
  84
  85 static struct irqaction pnx4008_timer_irq = {
  86         .name = "PNX4008 Tick Timer",
  87         .flags = IRQF_DISABLED | IRQF_TIMER,
  88         .handler = pnx4008_timer_interrupt
  89 };
  90
  91 /*!
  92  * Set up timer and timer interrupt.
  93  */
  94 static __init void pnx4008_setup_timer(void)
  95 {
  96         __raw_writel(RESET_COUNT, MSTIM_CTRL);
  97         while (__raw_readl(MSTIM_COUNTER)) ;    /* wait for reset to complete. 100% guarantee event */
  98         __raw_writel(0, MSTIM_CTRL);    /* stop the timer */
  99         __raw_writel(0, MSTIM_MCTRL);
 100
 101         __raw_writel(RESET_COUNT, HSTIM_CTRL);
 102         while (__raw_readl(HSTIM_COUNTER)) ;    /* wait for reset to complete. 100% guarantee event */
 103         __raw_writel(0, HSTIM_CTRL);
 104         __raw_writel(0, HSTIM_MCTRL);
 105         __raw_writel(0, HSTIM_CCR);
 106         __raw_writel(12, HSTIM_PMATCH); /* scale down to 1 MHZ */
 107         __raw_writel(LATCH, HSTIM_MATCH0);
 108         __raw_writel(MR0_INT, HSTIM_MCTRL);
 109
 110         setup_irq(HSTIMER_INT, &pnx4008_timer_irq);
 111
 112         __raw_writel(COUNT_ENAB | DEBUG_EN, HSTIM_CTRL);        /*start timer, stop when JTAG active */
 113 }
 114
 115 /* Timer Clock Control in PM register */
 116 #define TIMCLK_CTRL_REG  IO_ADDRESS((PNX4008_PWRMAN_BASE + 0xBC))
 117 #define WATCHDOG_CLK_EN                   1
 118 #define TIMER_CLK_EN                      2     /* HS and MS timers? */
 119
 120 static u32 timclk_ctrl_reg_save;
 121
 122 void pnx4008_timer_suspend(void)
 123 {
 124         timclk_ctrl_reg_save = __raw_readl(TIMCLK_CTRL_REG);
 125         __raw_writel(0, TIMCLK_CTRL_REG);       /* disable timers */
 126 }
 127
 128 void pnx4008_timer_resume(void)
 129 {
 130         __raw_writel(timclk_ctrl_reg_save, TIMCLK_CTRL_REG);    /* enable timers */
 131 }
 132
 133 struct sys_timer pnx4008_timer = {
 134         .init = pnx4008_setup_timer,
 135         .offset = pnx4008_gettimeoffset,
 136         .suspend = pnx4008_timer_suspend,
 137         .resume = pnx4008_timer_resume,
 138 };
 139