arch/ppc/syslib/m8xx_wdt.c

   1 /*
   2  * m8xx_wdt.c - MPC8xx watchdog driver
   3  *
   4  * Author: Florian Schirmer <jolt@tuxbox.org>
   5  *
   6  * 2002 (c) Florian Schirmer <jolt@tuxbox.org> This file is licensed under
   7  * the terms of the GNU General Public License version 2. This program
   8  * is licensed "as is" without any warranty of any kind, whether express
   9  * or implied.
  10  */
  11
  12 #include <linux/init.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/irq.h>
  15 #include <linux/kernel.h>
  16 #include <linux/sched.h>
  17 #include <asm/io.h>
  18 #include <asm/8xx_immap.h>
  19 #include <syslib/m8xx_wdt.h>
  20
  21 static int wdt_timeout;
  22 int m8xx_has_internal_rtc = 0;
  23
  24 static irqreturn_t m8xx_wdt_interrupt(int, void *);
  25 static struct irqaction m8xx_wdt_irqaction = {
  26         .handler = m8xx_wdt_interrupt,
  27         .name = "watchdog",
  28 };
  29
  30 void m8xx_wdt_reset(void)
  31 {
  32         volatile immap_t *imap = (volatile immap_t *)IMAP_ADDR;
  33
  34         out_be16(&imap->im_siu_conf.sc_swsr, 0x556c);   /* write magic1 */
  35         out_be16(&imap->im_siu_conf.sc_swsr, 0xaa39);   /* write magic2 */
  36 }
  37
  38 static irqreturn_t m8xx_wdt_interrupt(int irq, void *dev)
  39 {
  40         volatile immap_t *imap = (volatile immap_t *)IMAP_ADDR;
  41
  42         m8xx_wdt_reset();
  43
  44         setbits16(&imap->im_sit.sit_piscr, PISCR_PS);
  45         return IRQ_HANDLED;
  46 }
  47
  48 #define SYPCR_SWP 0x1
  49 #define SYPCR_SWE 0x4
  50
  51
  52 void __init m8xx_wdt_install_irq(volatile immap_t *imap, bd_t *binfo)
  53 {
  54         u32 pitc;
  55         u32 pitrtclk;
  56
  57         /*
  58          * Fire trigger if half of the wdt ticked down
  59          */
  60
  61         if (imap->im_sit.sit_rtcsc & RTCSC_38K)
  62                 pitrtclk = 9600;
  63         else
  64                 pitrtclk = 8192;
  65
  66         if ((wdt_timeout) > (UINT_MAX / pitrtclk))
  67                 pitc = wdt_timeout / binfo->bi_intfreq * pitrtclk / 2;
  68         else
  69                 pitc = pitrtclk * wdt_timeout / binfo->bi_intfreq / 2;
  70
  71         out_be32(&imap->im_sit.sit_pitc, pitc << 16);
  72
  73         out_be16(&imap->im_sit.sit_piscr, (mk_int_int_mask(PIT_INTERRUPT) << 8) | PISCR_PIE | PISCR_PTE);
  74
  75         if (setup_irq(PIT_INTERRUPT, &m8xx_wdt_irqaction))
  76                 panic("m8xx_wdt: error setting up the watchdog irq!");
  77
  78         printk(KERN_NOTICE
  79                "m8xx_wdt: keep-alive trigger installed (PITC: 0x%04X)\n", pitc);
  80
  81 }
  82
  83 static void m8xx_wdt_timer_func(unsigned long data);
  84
  85 static struct timer_list m8xx_wdt_timer =
  86         TIMER_INITIALIZER(m8xx_wdt_timer_func, 0, 0);
  87
  88 void m8xx_wdt_stop_timer(void)
  89 {
  90         del_timer(&m8xx_wdt_timer);
  91 }
  92
  93 void m8xx_wdt_install_timer(void)
  94 {
  95         m8xx_wdt_timer.expires = jiffies + (HZ/2);
  96         add_timer(&m8xx_wdt_timer);
  97 }
  98
  99 static void m8xx_wdt_timer_func(unsigned long data)
 100 {
 101         m8xx_wdt_reset();
 102         m8xx_wdt_install_timer();
 103 }
 104
 105 void __init m8xx_wdt_handler_install(bd_t * binfo)
 106 {
 107         volatile immap_t *imap = (volatile immap_t *)IMAP_ADDR;
 108         u32 sypcr;
 109
 110         sypcr = in_be32(&imap->im_siu_conf.sc_sypcr);
 111
 112         if (!(sypcr & SYPCR_SWE)) {
 113                 printk(KERN_NOTICE "m8xx_wdt: wdt disabled (SYPCR: 0x%08X)\n",
 114                        sypcr);
 115                 return;
 116         }
 117
 118         m8xx_wdt_reset();
 119
 120         printk(KERN_NOTICE
 121                "m8xx_wdt: active wdt found (SWTC: 0x%04X, SWP: 0x%01X)\n",
 122                (sypcr >> 16), sypcr & SYPCR_SWP);
 123
 124         wdt_timeout = (sypcr >> 16) & 0xFFFF;
 125
 126         if (!wdt_timeout)
 127                 wdt_timeout = 0xFFFF;
 128
 129         if (sypcr & SYPCR_SWP)
 130                 wdt_timeout *= 2048;
 131
 132         m8xx_has_internal_rtc = in_be16(&imap->im_sit.sit_rtcsc) & RTCSC_RTE;
 133
 134         /* if the internal RTC is off use a kernel timer */
 135         if (!m8xx_has_internal_rtc) {
 136                 if (wdt_timeout < (binfo->bi_intfreq/HZ))
 137                         printk(KERN_ERR "m8xx_wdt: timeout too short for ktimer!\n");
 138                 m8xx_wdt_install_timer();
 139         } else
 140                 m8xx_wdt_install_irq(imap, binfo);
 141
 142         wdt_timeout /= binfo->bi_intfreq;
 143 }
 144
 145 int m8xx_wdt_get_timeout(void)
 146 {
 147         return wdt_timeout;
 148 }