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

   1 #include <linux/linkage.h>
   2 #include <linux/sched.h>
   3 #include <linux/smp.h>
   4
   5 #include <asm/pmon.h>
   6 #include <asm/titan_dep.h>
   7 #include <asm/time.h>
   8
   9 #define LAUNCHSTACK_SIZE 256
  10
  11 static __cpuinitdata DEFINE_SPINLOCK(launch_lock);
  12
  13 static unsigned long secondary_sp __cpuinitdata;
  14 static unsigned long secondary_gp __cpuinitdata;
  15
  16 static unsigned char launchstack[LAUNCHSTACK_SIZE] __initdata
  17         __attribute__((aligned(2 * sizeof(long))));
  18
  19 static void __init prom_smp_bootstrap(void)
  20 {
  21         local_irq_disable();
  22
  23         while (spin_is_locked(&launch_lock));
  24
  25         __asm__ __volatile__(
  26         "       move    $sp, %0         \n"
  27         "       move    $gp, %1         \n"
  28         "       j       smp_bootstrap   \n"
  29         :
  30         : "r" (secondary_sp), "r" (secondary_gp));
  31 }
  32
  33 /*
  34  * PMON is a fragile beast.  It'll blow up once the mappings it's littering
  35  * right into the middle of KSEG3 are blown away so we have to grab the slave
  36  * core early and keep it in a waiting loop.
  37  */
  38 void __init prom_grab_secondary(void)
  39 {
  40         spin_lock(&launch_lock);
  41
  42         pmon_cpustart(1, &prom_smp_bootstrap,
  43                       launchstack + LAUNCHSTACK_SIZE, 0);
  44 }
  45
  46 void titan_mailbox_irq(void)
  47 {
  48         int cpu = smp_processor_id();
  49         unsigned long status;
  50
  51         switch (cpu) {
  52         case 0:
  53                 status = OCD_READ(RM9000x2_OCD_INTP0STATUS3);
  54                 OCD_WRITE(RM9000x2_OCD_INTP0CLEAR3, status);
  55
  56                 if (status & 0x2)
  57                         smp_call_function_interrupt();
  58                 break;
  59
  60         case 1:
  61                 status = OCD_READ(RM9000x2_OCD_INTP1STATUS3);
  62                 OCD_WRITE(RM9000x2_OCD_INTP1CLEAR3, status);
  63
  64                 if (status & 0x2)
  65                         smp_call_function_interrupt();
  66                 break;
  67         }
  68 }
  69
  70 /*
  71  * Send inter-processor interrupt
  72  */
  73 static void yos_send_ipi_single(int cpu, unsigned int action)
  74 {
  75         /*
  76          * Generate an INTMSG so that it can be sent over to the
  77          * destination CPU. The INTMSG will put the STATUS bits
  78          * based on the action desired. An alternative strategy
  79          * is to write to the Interrupt Set register, read the
  80          * Interrupt Status register and clear the Interrupt
  81          * Clear register. The latter is preffered.
  82          */
  83         switch (action) {
  84         case SMP_RESCHEDULE_YOURSELF:
  85                 if (cpu == 1)
  86                         OCD_WRITE(RM9000x2_OCD_INTP1SET3, 4);
  87                 else
  88                         OCD_WRITE(RM9000x2_OCD_INTP0SET3, 4);
  89                 break;
  90
  91         case SMP_CALL_FUNCTION:
  92                 if (cpu == 1)
  93                         OCD_WRITE(RM9000x2_OCD_INTP1SET3, 2);
  94                 else
  95                         OCD_WRITE(RM9000x2_OCD_INTP0SET3, 2);
  96                 break;
  97         }
  98 }
  99
 100 static void yos_send_ipi_mask(const struct cpumask *mask, unsigned int action)
 101 {
 102         unsigned int i;
 103
 104         for_each_cpu(i, mask)
 105                 yos_send_ipi_single(i, action);
 106 }
 107
 108 /*
 109  *  After we've done initial boot, this function is called to allow the
 110  *  board code to clean up state, if needed
 111  */
 112 static void __cpuinit yos_init_secondary(void)
 113 {
 114         set_c0_status(ST0_CO | ST0_IE | ST0_IM);
 115 }
 116
 117 static void __cpuinit yos_smp_finish(void)
 118 {
 119 }
 120
 121 /* Hook for after all CPUs are online */
 122 static void yos_cpus_done(void)
 123 {
 124 }
 125
 126 /*
 127  * Firmware CPU startup hook
 128  * Complicated by PMON's weird interface which tries to minimic the UNIX fork.
 129  * It launches the next * available CPU and copies some information on the
 130  * stack so the first thing we do is throw away that stuff and load useful
 131  * values into the registers ...
 132  */
 133 static void __cpuinit yos_boot_secondary(int cpu, struct task_struct *idle)
 134 {
 135         unsigned long gp = (unsigned long) task_thread_info(idle);
 136         unsigned long sp = __KSTK_TOS(idle);
 137
 138         secondary_sp = sp;
 139         secondary_gp = gp;
 140
 141         spin_unlock(&launch_lock);
 142 }
 143
 144 /*
 145  * Detect available CPUs, populate cpu_possible_map before smp_init
 146  *
 147  * We don't want to start the secondary CPU yet nor do we have a nice probing
 148  * feature in PMON so we just assume presence of the secondary core.
 149  */
 150 static void __init yos_smp_setup(void)
 151 {
 152         int i;
 153
 154         cpus_clear(cpu_possible_map);
 155
 156         for (i = 0; i < 2; i++) {
 157                 cpu_set(i, cpu_possible_map);
 158                 __cpu_number_map[i]     = i;
 159                 __cpu_logical_map[i]    = i;
 160         }
 161 }
 162
 163 static void __init yos_prepare_cpus(unsigned int max_cpus)
 164 {
 165         /*
 166          * Be paranoid.  Enable the IPI only if we're really about to go SMP.
 167          */
 168         if (cpus_weight(cpu_possible_map))
 169                 set_c0_status(STATUSF_IP5);
 170 }
 171
 172 struct plat_smp_ops yos_smp_ops = {
 173         .send_ipi_single        = yos_send_ipi_single,
 174         .send_ipi_mask          = yos_send_ipi_mask,
 175         .init_secondary         = yos_init_secondary,
 176         .smp_finish             = yos_smp_finish,
 177         .cpus_done              = yos_cpus_done,
 178         .boot_secondary         = yos_boot_secondary,
 179         .smp_setup              = yos_smp_setup,
 180         .prepare_cpus           = yos_prepare_cpus,
 181 };