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
  24 #include <asm/system.h>
  25 #include <asm/hardware.h>
  26 #include <asm/io.h>
  27 #include <asm/leds.h>
  28 #include <asm/irq.h>
  29 #include <asm/mach/irq.h>
  30 #include <asm/mach/time.h>
  31
  32 #include <linux/time.h>
  33 #include <linux/timex.h>
  34 #include <asm/errno.h>
  35
  36 /*! Note: all timers are UPCOUNTING */
  37
  38 /*!
  39  * Returns number of us since last clock interrupt.  Note that interrupts
  40  * will have been disabled by do_gettimeoffset()
  41  */
  42 static unsigned long pnx4008_gettimeoffset(void)
  43 {
  44         u32 ticks_to_match =
  45             __raw_readl(HSTIM_MATCH0) - __raw_readl(HSTIM_COUNTER);
  46         u32 elapsed = LATCH - ticks_to_match;
  47         return (elapsed * (tick_nsec / 1000)) / LATCH;
  48 }
  49
  50 /*!
  51  * IRQ handler for the timer
  52  */
  53 static irqreturn_t pnx4008_timer_interrupt(int irq, void *dev_id,
  54                                            struct pt_regs *regs)
  55 {
  56         if (__raw_readl(HSTIM_INT) & MATCH0_INT) {
  57
  58                 write_seqlock(&xtime_lock);
  59
  60                 do {
  61                         timer_tick(regs);
  62
  63                         /*
  64                          * this algorithm takes care of possible delay
  65                          * for this interrupt handling longer than a normal
  66                          * timer period
  67                          */
  68                         __raw_writel(__raw_readl(HSTIM_MATCH0) + LATCH,
  69                                      HSTIM_MATCH0);
  70                         __raw_writel(MATCH0_INT, HSTIM_INT);    /* clear interrupt */
  71
  72                         /*
  73                          * The goal is to keep incrementing HSTIM_MATCH0
  74                          * register until HSTIM_MATCH0 indicates time after
  75                          * what HSTIM_COUNTER indicates.
  76                          */
  77                 } while ((signed)
  78                          (__raw_readl(HSTIM_MATCH0) -
  79                           __raw_readl(HSTIM_COUNTER)) < 0);
  80
  81                 write_sequnlock(&xtime_lock);
  82         }
  83
  84         return IRQ_HANDLED;
  85 }
  86
  87 static struct irqaction pnx4008_timer_irq = {
  88         .name = "PNX4008 Tick Timer",
  89         .flags = SA_INTERRUPT | SA_TIMER,
  90         .handler = pnx4008_timer_interrupt
  91 };
  92
  93 /*!
  94  * Set up timer and timer interrupt.
  95  */
  96 static __init void pnx4008_setup_timer(void)
  97 {
  98         __raw_writel(RESET_COUNT, MSTIM_CTRL);
  99         while (__raw_readl(MSTIM_COUNTER)) ;    /* wait for reset to complete. 100% guarantee event */
 100         __raw_writel(0, MSTIM_CTRL);    /* stop the timer */
 101         __raw_writel(0, MSTIM_MCTRL);
 102
 103         __raw_writel(RESET_COUNT, HSTIM_CTRL);
 104         while (__raw_readl(HSTIM_COUNTER)) ;    /* wait for reset to complete. 100% guarantee event */
 105         __raw_writel(0, HSTIM_CTRL);
 106         __raw_writel(0, HSTIM_MCTRL);
 107         __raw_writel(0, HSTIM_CCR);
 108         __raw_writel(12, HSTIM_PMATCH); /* scale down to 1 MHZ */
 109         __raw_writel(LATCH, HSTIM_MATCH0);
 110         __raw_writel(MR0_INT, HSTIM_MCTRL);
 111
 112         setup_irq(HSTIMER_INT, &pnx4008_timer_irq);
 113
 114         __raw_writel(COUNT_ENAB | DEBUG_EN, HSTIM_CTRL);        /*start timer, stop when JTAG active */
 115 }
 116
 117 /* Timer Clock Control in PM register */
 118 #define TIMCLK_CTRL_REG  IO_ADDRESS((PNX4008_PWRMAN_BASE + 0xBC))
 119 #define WATCHDOG_CLK_EN                   1
 120 #define TIMER_CLK_EN                      2     /* HS and MS timers? */
 121
 122 static u32 timclk_ctrl_reg_save;
 123
 124 void pnx4008_timer_suspend(void)
 125 {
 126         timclk_ctrl_reg_save = __raw_readl(TIMCLK_CTRL_REG);
 127         __raw_writel(0, TIMCLK_CTRL_REG);       /* disable timers */
 128 }
 129
 130 void pnx4008_timer_resume(void)
 131 {
 132         __raw_writel(timclk_ctrl_reg_save, TIMCLK_CTRL_REG);    /* enable timers */
 133 }
 134
 135 struct sys_timer pnx4008_timer = {
 136         .init = pnx4008_setup_timer,
 137         .offset = pnx4008_gettimeoffset,
 138         .suspend = pnx4008_timer_suspend,
 139         .resume = pnx4008_timer_resume,
 140 };
 141