arch/powerpc/sysdev/xics/icp-opal.c

   1 /*
   2  * Copyright 2016 IBM Corporation.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version
   7  * 2 of the License, or (at your option) any later version.
   8  */
   9 #include <linux/types.h>
  10 #include <linux/kernel.h>
  11 #include <linux/irq.h>
  12 #include <linux/smp.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/cpu.h>
  15 #include <linux/of.h>
  16
  17 #include <asm/smp.h>
  18 #include <asm/irq.h>
  19 #include <asm/errno.h>
  20 #include <asm/xics.h>
  21 #include <asm/io.h>
  22 #include <asm/opal.h>
  23 #include <asm/kvm_ppc.h>
  24
  25 static void icp_opal_teardown_cpu(void)
  26 {
  27         int hw_cpu = hard_smp_processor_id();
  28
  29         /* Clear any pending IPI */
  30         opal_int_set_mfrr(hw_cpu, 0xff);
  31 }
  32
  33 static void icp_opal_flush_ipi(void)
  34 {
  35         /*
  36          * We take the ipi irq but and never return so we need to EOI the IPI,
  37          * but want to leave our priority 0.
  38          *
  39          * Should we check all the other interrupts too?
  40          * Should we be flagging idle loop instead?
  41          * Or creating some task to be scheduled?
  42          */
  43         if (opal_int_eoi((0x00 << 24) | XICS_IPI) > 0)
  44                 force_external_irq_replay();
  45 }
  46
  47 static unsigned int icp_opal_get_xirr(void)
  48 {
  49         unsigned int kvm_xirr;
  50         __be32 hw_xirr;
  51         int64_t rc;
  52
  53         /* Handle an interrupt latched by KVM first */
  54         kvm_xirr = kvmppc_get_xics_latch();
  55         if (kvm_xirr)
  56                 return kvm_xirr;
  57
  58         /* Then ask OPAL */
  59         rc = opal_int_get_xirr(&hw_xirr, false);
  60         if (rc < 0)
  61                 return 0;
  62         return be32_to_cpu(hw_xirr);
  63 }
  64
  65 static unsigned int icp_opal_get_irq(void)
  66 {
  67         unsigned int xirr;
  68         unsigned int vec;
  69         unsigned int irq;
  70
  71         xirr = icp_opal_get_xirr();
  72         vec = xirr & 0x00ffffff;
  73         if (vec == XICS_IRQ_SPURIOUS)
  74                 return 0;
  75
  76         irq = irq_find_mapping(xics_host, vec);
  77         if (likely(irq)) {
  78                 xics_push_cppr(vec);
  79                 return irq;
  80         }
  81
  82         /* We don't have a linux mapping, so have rtas mask it. */
  83         xics_mask_unknown_vec(vec);
  84
  85         /* We might learn about it later, so EOI it */
  86         if (opal_int_eoi(xirr) > 0)
  87                 force_external_irq_replay();
  88
  89         return 0;
  90 }
  91
  92 static void icp_opal_set_cpu_priority(unsigned char cppr)
  93 {
  94         /*
  95          * Here be dragons. The caller has asked to allow only IPI's and not
  96          * external interrupts. But OPAL XIVE doesn't support that. So instead
  97          * of allowing no interrupts allow all. That's still not right, but
  98          * currently the only caller who does this is xics_migrate_irqs_away()
  99          * and it works in that case.
 100          */
 101         if (cppr >= DEFAULT_PRIORITY)
 102                 cppr = LOWEST_PRIORITY;
 103
 104         xics_set_base_cppr(cppr);
 105         opal_int_set_cppr(cppr);
 106         iosync();
 107 }
 108
 109 static void icp_opal_eoi(struct irq_data *d)
 110 {
 111         unsigned int hw_irq = (unsigned int)irqd_to_hwirq(d);
 112         int64_t rc;
 113
 114         iosync();
 115         rc = opal_int_eoi((xics_pop_cppr() << 24) | hw_irq);
 116
 117         /*
 118          * EOI tells us whether there are more interrupts to fetch.
 119          *
 120          * Some HW implementations might not be able to send us another
 121          * external interrupt in that case, so we force a replay.
 122          */
 123         if (rc > 0)
 124                 force_external_irq_replay();
 125 }
 126
 127 #ifdef CONFIG_SMP
 128
 129 static void icp_opal_cause_ipi(int cpu)
 130 {
 131         int hw_cpu = get_hard_smp_processor_id(cpu);
 132
 133         kvmppc_set_host_ipi(cpu, 1);
 134         opal_int_set_mfrr(hw_cpu, IPI_PRIORITY);
 135 }
 136
 137 static irqreturn_t icp_opal_ipi_action(int irq, void *dev_id)
 138 {
 139         int cpu = smp_processor_id();
 140
 141         kvmppc_set_host_ipi(cpu, 0);
 142         opal_int_set_mfrr(get_hard_smp_processor_id(cpu), 0xff);
 143
 144         return smp_ipi_demux();
 145 }
 146
 147 /*
 148  * Called when an interrupt is received on an off-line CPU to
 149  * clear the interrupt, so that the CPU can go back to nap mode.
 150  */
 151 void icp_opal_flush_interrupt(void)
 152 {
 153         unsigned int xirr;
 154         unsigned int vec;
 155
 156         do {
 157                 xirr = icp_opal_get_xirr();
 158                 vec = xirr & 0x00ffffff;
 159                 if (vec == XICS_IRQ_SPURIOUS)
 160                         break;
 161                 if (vec == XICS_IPI) {
 162                         /* Clear pending IPI */
 163                         int cpu = smp_processor_id();
 164                         kvmppc_set_host_ipi(cpu, 0);
 165                         opal_int_set_mfrr(get_hard_smp_processor_id(cpu), 0xff);
 166                 } else {
 167                         pr_err("XICS: hw interrupt 0x%x to offline cpu, "
 168                                "disabling\n", vec);
 169                         xics_mask_unknown_vec(vec);
 170                 }
 171
 172                 /* EOI the interrupt */
 173         } while (opal_int_eoi(xirr) > 0);
 174 }
 175
 176 #endif /* CONFIG_SMP */
 177
 178 static const struct icp_ops icp_opal_ops = {
 179         .get_irq        = icp_opal_get_irq,
 180         .eoi            = icp_opal_eoi,
 181         .set_priority   = icp_opal_set_cpu_priority,
 182         .teardown_cpu   = icp_opal_teardown_cpu,
 183         .flush_ipi      = icp_opal_flush_ipi,
 184 #ifdef CONFIG_SMP
 185         .ipi_action     = icp_opal_ipi_action,
 186         .cause_ipi      = icp_opal_cause_ipi,
 187 #endif
 188 };
 189
 190 int icp_opal_init(void)
 191 {
 192         struct device_node *np;
 193
 194         np = of_find_compatible_node(NULL, NULL, "ibm,opal-intc");
 195         if (!np)
 196                 return -ENODEV;
 197
 198         icp_ops = &icp_opal_ops;
 199
 200         printk("XICS: Using OPAL ICP fallbacks\n");
 201
 202         return 0;
 203 }
 204