arch/sh/kernel/cpu/sh2/smp-j2.c

   1 /*
   2  * SMP support for J2 processor
   3  *
   4  * Copyright (C) 2015-2016 Smart Energy Instruments, Inc.
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License.  See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  */
  10
  11 #include <linux/smp.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/io.h>
  14 #include <linux/of_address.h>
  15 #include <linux/of_irq.h>
  16 #include <asm/cmpxchg.h>
  17
  18 DEFINE_PER_CPU(unsigned, j2_ipi_messages);
  19
  20 extern u32 *sh2_cpuid_addr;
  21 static u32 *j2_ipi_trigger;
  22 static int j2_ipi_irq;
  23
  24 static irqreturn_t j2_ipi_interrupt_handler(int irq, void *arg)
  25 {
  26         unsigned cpu = hard_smp_processor_id();
  27         volatile unsigned *pmsg = &per_cpu(j2_ipi_messages, cpu);
  28         unsigned messages, i;
  29
  30         do messages = *pmsg;
  31         while (cmpxchg(pmsg, messages, 0) != messages);
  32
  33         if (!messages) return IRQ_NONE;
  34
  35         for (i=0; i<SMP_MSG_NR; i++)
  36                 if (messages & (1U<<i))
  37                         smp_message_recv(i);
  38
  39         return IRQ_HANDLED;
  40 }
  41
  42 static void j2_smp_setup(void)
  43 {
  44 }
  45
  46 static void j2_prepare_cpus(unsigned int max_cpus)
  47 {
  48         struct device_node *np;
  49         unsigned i, max = 1;
  50
  51         np = of_find_compatible_node(NULL, NULL, "jcore,ipi-controller");
  52         if (!np)
  53                 goto out;
  54
  55         j2_ipi_irq = irq_of_parse_and_map(np, 0);
  56         j2_ipi_trigger = of_iomap(np, 0);
  57         if (!j2_ipi_irq || !j2_ipi_trigger)
  58                 goto out;
  59
  60         np = of_find_compatible_node(NULL, NULL, "jcore,cpuid-mmio");
  61         if (!np)
  62                 goto out;
  63
  64         sh2_cpuid_addr = of_iomap(np, 0);
  65         if (!sh2_cpuid_addr)
  66                 goto out;
  67
  68         if (request_irq(j2_ipi_irq, j2_ipi_interrupt_handler, IRQF_PERCPU,
  69                         "ipi", (void *)j2_ipi_interrupt_handler) != 0)
  70                 goto out;
  71
  72         max = max_cpus;
  73 out:
  74         /* Disable any cpus past max_cpus, or all secondaries if we didn't
  75          * get the necessary resources to support SMP. */
  76         for (i=max; i<NR_CPUS; i++) {
  77                 set_cpu_possible(i, false);
  78                 set_cpu_present(i, false);
  79         }
  80 }
  81
  82 static void j2_start_cpu(unsigned int cpu, unsigned long entry_point)
  83 {
  84         struct device_node *np;
  85         u32 regs[2];
  86         void __iomem *release, *initpc;
  87
  88         if (!cpu) return;
  89
  90         np = of_get_cpu_node(cpu, NULL);
  91         if (!np) return;
  92
  93         if (of_property_read_u32_array(np, "cpu-release-addr", regs, 2)) return;
  94         release = ioremap_nocache(regs[0], sizeof(u32));
  95         initpc = ioremap_nocache(regs[1], sizeof(u32));
  96
  97         __raw_writel(entry_point, initpc);
  98         __raw_writel(1, release);
  99
 100         iounmap(initpc);
 101         iounmap(release);
 102
 103         pr_info("J2 SMP: requested start of cpu %u\n", cpu);
 104 }
 105
 106 static unsigned int j2_smp_processor_id(void)
 107 {
 108         return __raw_readl(sh2_cpuid_addr);
 109 }
 110
 111 static void j2_send_ipi(unsigned int cpu, unsigned int message)
 112 {
 113         volatile unsigned *pmsg;
 114         unsigned old;
 115         unsigned long val;
 116
 117         /* There is only one IPI interrupt shared by all messages, so
 118          * we keep a separate interrupt flag per message type in sw. */
 119         pmsg = &per_cpu(j2_ipi_messages, cpu);
 120         do old = *pmsg;
 121         while (cmpxchg(pmsg, old, old|(1U<<message)) != old);
 122
 123         /* Generate the actual interrupt by writing to CCRn bit 28. */
 124         val = __raw_readl(j2_ipi_trigger + cpu);
 125         __raw_writel(val | (1U<<28), j2_ipi_trigger + cpu);
 126 }
 127
 128 static struct plat_smp_ops j2_smp_ops = {
 129         .smp_setup              = j2_smp_setup,
 130         .prepare_cpus           = j2_prepare_cpus,
 131         .start_cpu              = j2_start_cpu,
 132         .smp_processor_id       = j2_smp_processor_id,
 133         .send_ipi               = j2_send_ipi,
 134         .cpu_die                = native_cpu_die,
 135         .cpu_disable            = native_cpu_disable,
 136         .play_dead              = native_play_dead,
 137 };
 138
 139 CPU_METHOD_OF_DECLARE(j2_cpu_method, "jcore,spin-table", &j2_smp_ops);