arch/mips/pmc-sierra/yosemite/smp.c

   1 #include <linux/linkage.h>
   2 #include <linux/sched.h>
   3
   4 #include <asm/pmon.h>
   5 #include <asm/titan_dep.h>
   6 #include <asm/time.h>
   7
   8 #define LAUNCHSTACK_SIZE 256
   9
  10 static __cpuinitdata DEFINE_SPINLOCK(launch_lock);
  11
  12 static unsigned long secondary_sp __cpuinitdata;
  13 static unsigned long secondary_gp __cpuinitdata;
  14
  15 static unsigned char launchstack[LAUNCHSTACK_SIZE] __initdata
  16         __attribute__((aligned(2 * sizeof(long))));
  17
  18 static void __init prom_smp_bootstrap(void)
  19 {
  20         local_irq_disable();
  21
  22         while (spin_is_locked(&launch_lock));
  23
  24         __asm__ __volatile__(
  25         "       move    $sp, %0         \n"
  26         "       move    $gp, %1         \n"
  27         "       j       smp_bootstrap   \n"
  28         :
  29         : "r" (secondary_sp), "r" (secondary_gp));
  30 }
  31
  32 /*
  33  * PMON is a fragile beast.  It'll blow up once the mappings it's littering
  34  * right into the middle of KSEG3 are blown away so we have to grab the slave
  35  * core early and keep it in a waiting loop.
  36  */
  37 void __init prom_grab_secondary(void)
  38 {
  39         spin_lock(&launch_lock);
  40
  41         pmon_cpustart(1, &prom_smp_bootstrap,
  42                       launchstack + LAUNCHSTACK_SIZE, 0);
  43 }
  44
  45 void titan_mailbox_irq(void)
  46 {
  47         int cpu = smp_processor_id();
  48         unsigned long status;
  49
  50         switch (cpu) {
  51         case 0:
  52                 status = OCD_READ(RM9000x2_OCD_INTP0STATUS3);
  53                 OCD_WRITE(RM9000x2_OCD_INTP0CLEAR3, status);
  54
  55                 if (status & 0x2)
  56                         smp_call_function_interrupt();
  57                 break;
  58
  59         case 1:
  60                 status = OCD_READ(RM9000x2_OCD_INTP1STATUS3);
  61                 OCD_WRITE(RM9000x2_OCD_INTP1CLEAR3, status);
  62
  63                 if (status & 0x2)
  64                         smp_call_function_interrupt();
  65                 break;
  66         }
  67 }
  68
  69 /*
  70  * Send inter-processor interrupt
  71  */
  72 static void yos_send_ipi_single(int cpu, unsigned int action)
  73 {
  74         /*
  75          * Generate an INTMSG so that it can be sent over to the
  76          * destination CPU. The INTMSG will put the STATUS bits
  77          * based on the action desired. An alternative strategy
  78          * is to write to the Interrupt Set register, read the
  79          * Interrupt Status register and clear the Interrupt
  80          * Clear register. The latter is preffered.
  81          */
  82         switch (action) {
  83         case SMP_RESCHEDULE_YOURSELF:
  84                 if (cpu == 1)
  85                         OCD_WRITE(RM9000x2_OCD_INTP1SET3, 4);
  86                 else
  87                         OCD_WRITE(RM9000x2_OCD_INTP0SET3, 4);
  88                 break;
  89
  90         case SMP_CALL_FUNCTION:
  91                 if (cpu == 1)
  92                         OCD_WRITE(RM9000x2_OCD_INTP1SET3, 2);
  93                 else
  94                         OCD_WRITE(RM9000x2_OCD_INTP0SET3, 2);
  95                 break;
  96         }
  97 }
  98
  99 static void yos_send_ipi_mask(cpumask_t mask, unsigned int action)
 100 {
 101         unsigned int i;
 102
 103         for_each_cpu_mask(i, mask)
 104                 yos_send_ipi_single(i, action);
 105 }
 106
 107 /*
 108  *  After we've done initial boot, this function is called to allow the
 109  *  board code to clean up state, if needed
 110  */
 111 static void __cpuinit yos_init_secondary(void)
 112 {
 113         set_c0_status(ST0_CO | ST0_IE | ST0_IM);
 114 }
 115
 116 static void __cpuinit yos_smp_finish(void)
 117 {
 118 }
 119
 120 /* Hook for after all CPUs are online */
 121 static void yos_cpus_done(void)
 122 {
 123 }
 124
 125 /*
 126  * Firmware CPU startup hook
 127  * Complicated by PMON's weird interface which tries to minimic the UNIX fork.
 128  * It launches the next * available CPU and copies some information on the
 129  * stack so the first thing we do is throw away that stuff and load useful
 130  * values into the registers ...
 131  */
 132 static void __cpuinit yos_boot_secondary(int cpu, struct task_struct *idle)
 133 {
 134         unsigned long gp = (unsigned long) task_thread_info(idle);
 135         unsigned long sp = __KSTK_TOS(idle);
 136
 137         secondary_sp = sp;
 138         secondary_gp = gp;
 139
 140         spin_unlock(&launch_lock);
 141 }
 142
 143 /*
 144  * Detect available CPUs, populate cpu_possible_map before smp_init
 145  *
 146  * We don't want to start the secondary CPU yet nor do we have a nice probing
 147  * feature in PMON so we just assume presence of the secondary core.
 148  */
 149 static void __init yos_smp_setup(void)
 150 {
 151         int i;
 152
 153         cpus_clear(cpu_possible_map);
 154
 155         for (i = 0; i < 2; i++) {
 156                 cpu_set(i, cpu_possible_map);
 157                 __cpu_number_map[i]     = i;
 158                 __cpu_logical_map[i]    = i;
 159         }
 160 }
 161
 162 static void __init yos_prepare_cpus(unsigned int max_cpus)
 163 {
 164         /*
 165          * Be paranoid.  Enable the IPI only if we're really about to go SMP.
 166          */
 167         if (cpus_weight(cpu_possible_map))
 168                 set_c0_status(STATUSF_IP5);
 169 }
 170
 171 struct plat_smp_ops yos_smp_ops = {
 172         .send_ipi_single        = yos_send_ipi_single,
 173         .send_ipi_mask          = yos_send_ipi_mask,
 174         .init_secondary         = yos_init_secondary,
 175         .smp_finish             = yos_smp_finish,
 176         .cpus_done              = yos_cpus_done,
 177         .boot_secondary         = yos_boot_secondary,
 178         .smp_setup              = yos_smp_setup,
 179         .prepare_cpus           = yos_prepare_cpus,
 180 };