arch/sh/boards/saturn/smp.c

   1 /*
   2  * arch/sh/boards/saturn/smp.c
   3  *
   4  * SMP support for the Sega Saturn.
   5  *
   6  * Copyright (c) 2002 Paul Mundt
   7  *
   8  * Released under the terms of the GNU GPL v2.0.
   9  */
  10 #include <linux/kernel.h>
  11 #include <linux/init.h>
  12 #include <linux/smp.h>
  13
  14 #include <asm/saturn/smpc.h>
  15
  16 extern void start_secondary(void);
  17
  18 void __smp_send_ipi(unsigned int cpu, unsigned int action)
  19 {
  20         /* Nothing here yet .. */
  21 }
  22
  23 unsigned int __smp_probe_cpus(void)
  24 {
  25         /*
  26          * This is just a straightforward master/slave configuration,
  27          * and probing isn't really supported..
  28          */
  29         return 2;
  30 }
  31
  32 /*
  33  * We're only allowed to do byte-access to SMPC registers. In
  34  * addition to which, we treat them as write-only, since
  35  * reading from them will return undefined data.
  36  */
  37 static inline void smpc_slave_stop(unsigned int cpu)
  38 {
  39         smpc_barrier();
  40         ctrl_outb(1, SMPC_STATUS);
  41
  42         ctrl_outb(SMPC_CMD_SSHOFF, SMPC_COMMAND);
  43         smpc_barrier();
  44 }
  45
  46 static inline void smpc_slave_start(unsigned int cpu)
  47 {
  48         ctrl_outb(1, SMPC_STATUS);
  49         ctrl_outb(SMPC_CMD_SSHON, SMPC_COMMAND);
  50
  51         smpc_barrier();
  52 }
  53
  54 void __smp_slave_init(unsigned int cpu)
  55 {
  56         register unsigned long vbr;
  57         void **entry;
  58
  59         __asm__ __volatile__ ("stc vbr, %0\n\t" : "=r" (vbr));
  60         entry = (void **)(vbr + 0x310 + 0x94);
  61
  62         smpc_slave_stop(cpu);
  63
  64         *(void **)entry = (void *)start_secondary;
  65
  66         smpc_slave_start(cpu);
  67 }
  68