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/kernel.h>
  15 #include <linux/sched.h>
  16 #include <asm/8xx_immap.h>
  17 #include <syslib/m8xx_wdt.h>
  18
  19 static int wdt_timeout;
  20
  21 void m8xx_wdt_reset(void)
  22 {
  23         volatile immap_t *imap = (volatile immap_t *)IMAP_ADDR;
  24
  25         imap->im_siu_conf.sc_swsr = 0x556c;     /* write magic1 */
  26         imap->im_siu_conf.sc_swsr = 0xaa39;     /* write magic2 */
  27 }
  28
  29 static irqreturn_t m8xx_wdt_interrupt(int irq, void *dev, struct pt_regs *regs)
  30 {
  31         volatile immap_t *imap = (volatile immap_t *)IMAP_ADDR;
  32
  33         m8xx_wdt_reset();
  34
  35         imap->im_sit.sit_piscr |= PISCR_PS;     /* clear irq */
  36
  37         return IRQ_HANDLED;
  38 }
  39
  40 void __init m8xx_wdt_handler_install(bd_t * binfo)
  41 {
  42         volatile immap_t *imap = (volatile immap_t *)IMAP_ADDR;
  43         u32 pitc;
  44         u32 sypcr;
  45         u32 pitrtclk;
  46
  47         sypcr = imap->im_siu_conf.sc_sypcr;
  48
  49         if (!(sypcr & 0x04)) {
  50                 printk(KERN_NOTICE "m8xx_wdt: wdt disabled (SYPCR: 0x%08X)\n",
  51                        sypcr);
  52                 return;
  53         }
  54
  55         m8xx_wdt_reset();
  56
  57         printk(KERN_NOTICE
  58                "m8xx_wdt: active wdt found (SWTC: 0x%04X, SWP: 0x%01X)\n",
  59                (sypcr >> 16), sypcr & 0x01);
  60
  61         wdt_timeout = (sypcr >> 16) & 0xFFFF;
  62
  63         if (!wdt_timeout)
  64                 wdt_timeout = 0xFFFF;
  65
  66         if (sypcr & 0x01)
  67                 wdt_timeout *= 2048;
  68
  69         /*
  70          * Fire trigger if half of the wdt ticked down
  71          */
  72
  73         if (imap->im_sit.sit_rtcsc & RTCSC_38K)
  74                 pitrtclk = 9600;
  75         else
  76                 pitrtclk = 8192;
  77
  78         if ((wdt_timeout) > (UINT_MAX / pitrtclk))
  79                 pitc = wdt_timeout / binfo->bi_intfreq * pitrtclk / 2;
  80         else
  81                 pitc = pitrtclk * wdt_timeout / binfo->bi_intfreq / 2;
  82
  83         imap->im_sit.sit_pitc = pitc << 16;
  84         imap->im_sit.sit_piscr =
  85             (mk_int_int_mask(PIT_INTERRUPT) << 8) | PISCR_PIE | PISCR_PTE;
  86
  87         if (request_irq(PIT_INTERRUPT, m8xx_wdt_interrupt, 0, "watchdog", NULL))
  88                 panic("m8xx_wdt: could not allocate watchdog irq!");
  89
  90         printk(KERN_NOTICE
  91                "m8xx_wdt: keep-alive trigger installed (PITC: 0x%04X)\n", pitc);
  92
  93         wdt_timeout /= binfo->bi_intfreq;
  94 }
  95
  96 int m8xx_wdt_get_timeout(void)
  97 {
  98         return wdt_timeout;
  99 }