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/8xx_immap.h>
  18 #include <syslib/m8xx_wdt.h>
  19
  20 static int wdt_timeout;
  21
  22 static irqreturn_t m8xx_wdt_interrupt(int, void *, struct pt_regs *);
  23 static struct irqaction m8xx_wdt_irqaction = {
  24         .handler = m8xx_wdt_interrupt,
  25         .name = "watchdog",
  26 };
  27
  28 void m8xx_wdt_reset(void)
  29 {
  30         volatile immap_t *imap = (volatile immap_t *)IMAP_ADDR;
  31
  32         imap->im_siu_conf.sc_swsr = 0x556c;     /* write magic1 */
  33         imap->im_siu_conf.sc_swsr = 0xaa39;     /* write magic2 */
  34 }
  35
  36 static irqreturn_t m8xx_wdt_interrupt(int irq, void *dev, struct pt_regs *regs)
  37 {
  38         volatile immap_t *imap = (volatile immap_t *)IMAP_ADDR;
  39
  40         m8xx_wdt_reset();
  41
  42         imap->im_sit.sit_piscr |= PISCR_PS;     /* clear irq */
  43
  44         return IRQ_HANDLED;
  45 }
  46
  47 void __init m8xx_wdt_handler_install(bd_t * binfo)
  48 {
  49         volatile immap_t *imap = (volatile immap_t *)IMAP_ADDR;
  50         u32 pitc;
  51         u32 sypcr;
  52         u32 pitrtclk;
  53
  54         sypcr = imap->im_siu_conf.sc_sypcr;
  55
  56         if (!(sypcr & 0x04)) {
  57                 printk(KERN_NOTICE "m8xx_wdt: wdt disabled (SYPCR: 0x%08X)\n",
  58                        sypcr);
  59                 return;
  60         }
  61
  62         m8xx_wdt_reset();
  63
  64         printk(KERN_NOTICE
  65                "m8xx_wdt: active wdt found (SWTC: 0x%04X, SWP: 0x%01X)\n",
  66                (sypcr >> 16), sypcr & 0x01);
  67
  68         wdt_timeout = (sypcr >> 16) & 0xFFFF;
  69
  70         if (!wdt_timeout)
  71                 wdt_timeout = 0xFFFF;
  72
  73         if (sypcr & 0x01)
  74                 wdt_timeout *= 2048;
  75
  76         /*
  77          * Fire trigger if half of the wdt ticked down
  78          */
  79
  80         if (imap->im_sit.sit_rtcsc & RTCSC_38K)
  81                 pitrtclk = 9600;
  82         else
  83                 pitrtclk = 8192;
  84
  85         if ((wdt_timeout) > (UINT_MAX / pitrtclk))
  86                 pitc = wdt_timeout / binfo->bi_intfreq * pitrtclk / 2;
  87         else
  88                 pitc = pitrtclk * wdt_timeout / binfo->bi_intfreq / 2;
  89
  90         imap->im_sit.sit_pitc = pitc << 16;
  91         imap->im_sit.sit_piscr =
  92             (mk_int_int_mask(PIT_INTERRUPT) << 8) | PISCR_PIE | PISCR_PTE;
  93
  94         if (setup_irq(PIT_INTERRUPT, &m8xx_wdt_irqaction))
  95                 panic("m8xx_wdt: error setting up the watchdog irq!");
  96
  97         printk(KERN_NOTICE
  98                "m8xx_wdt: keep-alive trigger installed (PITC: 0x%04X)\n", pitc);
  99
 100         wdt_timeout /= binfo->bi_intfreq;
 101 }
 102
 103 int m8xx_wdt_get_timeout(void)
 104 {
 105         return wdt_timeout;
 106 }