MIPS: Coherent Processing System SMP implementation
This patch introduces a new SMP implementation for systems implementing
the MIPS Coherent Processing System architecture. The kernel will make
use of the Coherence Manager, Cluster Power Controller & Global
Interrupt Controller in order to detect, bring up & make use of other
cores in the system. SMTC is not supported, so only a single TC per VPE
in the system is used. That is, this option enables an SMVP style setup
but across multiple cores.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6362/
Patchwork: https://patchwork.linux-mips.org/patch/6611/
Patchwork: https://patchwork.linux-mips.org/patch/6651/
Patchwork: https://patchwork.linux-mips.org/patch/6652/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/smp-cps.c b/arch/mips/kernel/smp-cps.c
new file mode 100644
index 0000000..536eec0
--- /dev/null
+++ b/arch/mips/kernel/smp-cps.c
@@ -0,0 +1,335 @@
+/*
+ * Copyright (C) 2013 Imagination Technologies
+ * Author: Paul Burton <paul.burton@imgtec.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/io.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/smp.h>
+#include <linux/types.h>
+
+#include <asm/cacheflush.h>
+#include <asm/gic.h>
+#include <asm/mips-cm.h>
+#include <asm/mips-cpc.h>
+#include <asm/mips_mt.h>
+#include <asm/mipsregs.h>
+#include <asm/smp-cps.h>
+#include <asm/time.h>
+#include <asm/uasm.h>
+
+static DECLARE_BITMAP(core_power, NR_CPUS);
+
+struct boot_config mips_cps_bootcfg;
+
+static void init_core(void)
+{
+ unsigned int nvpes, t;
+ u32 mvpconf0, vpeconf0, vpecontrol, tcstatus, tcbind, status;
+
+ if (!cpu_has_mipsmt)
+ return;
+
+ /* Enter VPE configuration state */
+ dvpe();
+ set_c0_mvpcontrol(MVPCONTROL_VPC);
+
+ /* Retrieve the count of VPEs in this core */
+ mvpconf0 = read_c0_mvpconf0();
+ nvpes = ((mvpconf0 & MVPCONF0_PVPE) >> MVPCONF0_PVPE_SHIFT) + 1;
+ smp_num_siblings = nvpes;
+
+ for (t = 1; t < nvpes; t++) {
+ /* Use a 1:1 mapping of TC index to VPE index */
+ settc(t);
+
+ /* Bind 1 TC to this VPE */
+ tcbind = read_tc_c0_tcbind();
+ tcbind &= ~TCBIND_CURVPE;
+ tcbind |= t << TCBIND_CURVPE_SHIFT;
+ write_tc_c0_tcbind(tcbind);
+
+ /* Set exclusive TC, non-active, master */
+ vpeconf0 = read_vpe_c0_vpeconf0();
+ vpeconf0 &= ~(VPECONF0_XTC | VPECONF0_VPA);
+ vpeconf0 |= t << VPECONF0_XTC_SHIFT;
+ vpeconf0 |= VPECONF0_MVP;
+ write_vpe_c0_vpeconf0(vpeconf0);
+
+ /* Declare TC non-active, non-allocatable & interrupt exempt */
+ tcstatus = read_tc_c0_tcstatus();
+ tcstatus &= ~(TCSTATUS_A | TCSTATUS_DA);
+ tcstatus |= TCSTATUS_IXMT;
+ write_tc_c0_tcstatus(tcstatus);
+
+ /* Halt the TC */
+ write_tc_c0_tchalt(TCHALT_H);
+
+ /* Allow only 1 TC to execute */
+ vpecontrol = read_vpe_c0_vpecontrol();
+ vpecontrol &= ~VPECONTROL_TE;
+ write_vpe_c0_vpecontrol(vpecontrol);
+
+ /* Copy (most of) Status from VPE 0 */
+ status = read_c0_status();
+ status &= ~(ST0_IM | ST0_IE | ST0_KSU);
+ status |= ST0_CU0;
+ write_vpe_c0_status(status);
+
+ /* Copy Config from VPE 0 */
+ write_vpe_c0_config(read_c0_config());
+ write_vpe_c0_config7(read_c0_config7());
+
+ /* Ensure no software interrupts are pending */
+ write_vpe_c0_cause(0);
+
+ /* Sync Count */
+ write_vpe_c0_count(read_c0_count());
+ }
+
+ /* Leave VPE configuration state */
+ clear_c0_mvpcontrol(MVPCONTROL_VPC);
+}
+
+static void __init cps_smp_setup(void)
+{
+ unsigned int ncores, nvpes, core_vpes;
+ int c, v;
+ u32 core_cfg, *entry_code;
+
+ /* Detect & record VPE topology */
+ ncores = mips_cm_numcores();
+ pr_info("VPE topology ");
+ for (c = nvpes = 0; c < ncores; c++) {
+ if (cpu_has_mipsmt && config_enabled(CONFIG_MIPS_MT_SMP)) {
+ write_gcr_cl_other(c << CM_GCR_Cx_OTHER_CORENUM_SHF);
+ core_cfg = read_gcr_co_config();
+ core_vpes = ((core_cfg & CM_GCR_Cx_CONFIG_PVPE_MSK) >>
+ CM_GCR_Cx_CONFIG_PVPE_SHF) + 1;
+ } else {
+ core_vpes = 1;
+ }
+
+ pr_cont("%c%u", c ? ',' : '{', core_vpes);
+
+ for (v = 0; v < min_t(int, core_vpes, NR_CPUS - nvpes); v++) {
+ cpu_data[nvpes + v].core = c;
+#ifdef CONFIG_MIPS_MT_SMP
+ cpu_data[nvpes + v].vpe_id = v;
+#endif
+ }
+
+ nvpes += core_vpes;
+ }
+ pr_cont("} total %u\n", nvpes);
+
+ /* Indicate present CPUs (CPU being synonymous with VPE) */
+ for (v = 0; v < min_t(unsigned, nvpes, NR_CPUS); v++) {
+ set_cpu_possible(v, true);
+ set_cpu_present(v, true);
+ __cpu_number_map[v] = v;
+ __cpu_logical_map[v] = v;
+ }
+
+ /* Core 0 is powered up (we're running on it) */
+ bitmap_set(core_power, 0, 1);
+
+ /* Disable MT - we only want to run 1 TC per VPE */
+ if (cpu_has_mipsmt)
+ dmt();
+
+ /* Initialise core 0 */
+ init_core();
+
+ /* Patch the start of mips_cps_core_entry to provide the CM base */
+ entry_code = (u32 *)&mips_cps_core_entry;
+ UASM_i_LA(&entry_code, 3, (long)mips_cm_base);
+
+ /* Make core 0 coherent with everything */
+ write_gcr_cl_coherence(0xff);
+}
+
+static void __init cps_prepare_cpus(unsigned int max_cpus)
+{
+ mips_mt_set_cpuoptions();
+}
+
+static void boot_core(struct boot_config *cfg)
+{
+ u32 access;
+
+ /* Select the appropriate core */
+ write_gcr_cl_other(cfg->core << CM_GCR_Cx_OTHER_CORENUM_SHF);
+
+ /* Set its reset vector */
+ write_gcr_co_reset_base(CKSEG1ADDR((unsigned long)mips_cps_core_entry));
+
+ /* Ensure its coherency is disabled */
+ write_gcr_co_coherence(0);
+
+ /* Ensure the core can access the GCRs */
+ access = read_gcr_access();
+ access |= 1 << (CM_GCR_ACCESS_ACCESSEN_SHF + cfg->core);
+ write_gcr_access(access);
+
+ /* Copy cfg */
+ mips_cps_bootcfg = *cfg;
+
+ if (mips_cpc_present()) {
+ /* Select the appropriate core */
+ write_cpc_cl_other(cfg->core << CPC_Cx_OTHER_CORENUM_SHF);
+
+ /* Reset the core */
+ write_cpc_co_cmd(CPC_Cx_CMD_RESET);
+ } else {
+ /* Take the core out of reset */
+ write_gcr_co_reset_release(0);
+ }
+
+ /* The core is now powered up */
+ bitmap_set(core_power, cfg->core, 1);
+}
+
+static void boot_vpe(void *info)
+{
+ struct boot_config *cfg = info;
+ u32 tcstatus, vpeconf0;
+
+ /* Enter VPE configuration state */
+ dvpe();
+ set_c0_mvpcontrol(MVPCONTROL_VPC);
+
+ settc(cfg->vpe);
+
+ /* Set the TC restart PC */
+ write_tc_c0_tcrestart((unsigned long)&smp_bootstrap);
+
+ /* Activate the TC, allow interrupts */
+ tcstatus = read_tc_c0_tcstatus();
+ tcstatus &= ~TCSTATUS_IXMT;
+ tcstatus |= TCSTATUS_A;
+ write_tc_c0_tcstatus(tcstatus);
+
+ /* Clear the TC halt bit */
+ write_tc_c0_tchalt(0);
+
+ /* Activate the VPE */
+ vpeconf0 = read_vpe_c0_vpeconf0();
+ vpeconf0 |= VPECONF0_VPA;
+ write_vpe_c0_vpeconf0(vpeconf0);
+
+ /* Set the stack & global pointer registers */
+ write_tc_gpr_sp(cfg->sp);
+ write_tc_gpr_gp(cfg->gp);
+
+ /* Leave VPE configuration state */
+ clear_c0_mvpcontrol(MVPCONTROL_VPC);
+
+ /* Enable other VPEs to execute */
+ evpe(EVPE_ENABLE);
+}
+
+static void cps_boot_secondary(int cpu, struct task_struct *idle)
+{
+ struct boot_config cfg;
+ unsigned int remote;
+ int err;
+
+ cfg.core = cpu_data[cpu].core;
+ cfg.vpe = cpu_vpe_id(&cpu_data[cpu]);
+ cfg.pc = (unsigned long)&smp_bootstrap;
+ cfg.sp = __KSTK_TOS(idle);
+ cfg.gp = (unsigned long)task_thread_info(idle);
+
+ if (!test_bit(cfg.core, core_power)) {
+ /* Boot a VPE on a powered down core */
+ boot_core(&cfg);
+ return;
+ }
+
+ if (cfg.core != current_cpu_data.core) {
+ /* Boot a VPE on another powered up core */
+ for (remote = 0; remote < NR_CPUS; remote++) {
+ if (cpu_data[remote].core != cfg.core)
+ continue;
+ if (cpu_online(remote))
+ break;
+ }
+ BUG_ON(remote >= NR_CPUS);
+
+ err = smp_call_function_single(remote, boot_vpe, &cfg, 1);
+ if (err)
+ panic("Failed to call remote CPU\n");
+ return;
+ }
+
+ BUG_ON(!cpu_has_mipsmt);
+
+ /* Boot a VPE on this core */
+ boot_vpe(&cfg);
+}
+
+static void cps_init_secondary(void)
+{
+ /* Disable MT - we only want to run 1 TC per VPE */
+ if (cpu_has_mipsmt)
+ dmt();
+
+ /* TODO: revisit this assumption once hotplug is implemented */
+ if (cpu_vpe_id(¤t_cpu_data) == 0)
+ init_core();
+
+ change_c0_status(ST0_IM, STATUSF_IP3 | STATUSF_IP4 |
+ STATUSF_IP6 | STATUSF_IP7);
+}
+
+static void cps_smp_finish(void)
+{
+ write_c0_compare(read_c0_count() + (8 * mips_hpt_frequency / HZ));
+
+#ifdef CONFIG_MIPS_MT_FPAFF
+ /* If we have an FPU, enroll ourselves in the FPU-full mask */
+ if (cpu_has_fpu)
+ cpu_set(smp_processor_id(), mt_fpu_cpumask);
+#endif /* CONFIG_MIPS_MT_FPAFF */
+
+ local_irq_enable();
+}
+
+static void cps_cpus_done(void)
+{
+}
+
+static struct plat_smp_ops cps_smp_ops = {
+ .smp_setup = cps_smp_setup,
+ .prepare_cpus = cps_prepare_cpus,
+ .boot_secondary = cps_boot_secondary,
+ .init_secondary = cps_init_secondary,
+ .smp_finish = cps_smp_finish,
+ .send_ipi_single = gic_send_ipi_single,
+ .send_ipi_mask = gic_send_ipi_mask,
+ .cpus_done = cps_cpus_done,
+};
+
+int register_cps_smp_ops(void)
+{
+ if (!mips_cm_present()) {
+ pr_warn("MIPS CPS SMP unable to proceed without a CM\n");
+ return -ENODEV;
+ }
+
+ /* check we have a GIC - we need one for IPIs */
+ if (!(read_gcr_gic_status() & CM_GCR_GIC_STATUS_EX_MSK)) {
+ pr_warn("MIPS CPS SMP unable to proceed without a GIC\n");
+ return -ENODEV;
+ }
+
+ register_smp_ops(&cps_smp_ops);
+ return 0;
+}