/* * Copyright (C) 2014 Imagination Technologies * Author: Paul Burton * * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * cps_nc_entry_fn - type of a generated non-coherent state entry function * @online: the count of online coupled VPEs * @nc_ready_count: pointer to a non-coherent mapping of the core ready_count * * The code entering & exiting non-coherent states is generated at runtime * using uasm, in order to ensure that the compiler cannot insert a stray * memory access at an unfortunate time and to allow the generation of optimal * core-specific code particularly for cache routines. If coupled_coherence * is non-zero and this is the entry function for the CPS_PM_NC_WAIT state, * returns the number of VPEs that were in the wait state at the point this * VPE left it. Returns garbage if coupled_coherence is zero or this is not * the entry function for CPS_PM_NC_WAIT. */ typedef unsigned (*cps_nc_entry_fn)(unsigned online, u32 *nc_ready_count); /* * The entry point of the generated non-coherent idle state entry/exit * functions. Actually per-core rather than per-CPU. */ static DEFINE_PER_CPU_READ_MOSTLY(cps_nc_entry_fn[CPS_PM_STATE_COUNT], nc_asm_enter); /* Bitmap indicating which states are supported by the system */ static DECLARE_BITMAP(state_support, CPS_PM_STATE_COUNT); /* * Indicates the number of coupled VPEs ready to operate in a non-coherent * state. Actually per-core rather than per-CPU. */ static DEFINE_PER_CPU_ALIGNED(u32*, ready_count); /* Indicates online CPUs coupled with the current CPU */ static DEFINE_PER_CPU_ALIGNED(cpumask_t, online_coupled); /* * Used to synchronize entry to deep idle states. Actually per-core rather * than per-CPU. */ static DEFINE_PER_CPU_ALIGNED(atomic_t, pm_barrier); /* Saved CPU state across the CPS_PM_POWER_GATED state */ DEFINE_PER_CPU_ALIGNED(struct mips_static_suspend_state, cps_cpu_state); /* A somewhat arbitrary number of labels & relocs for uasm */ static struct uasm_label labels[32]; static struct uasm_reloc relocs[32]; enum mips_reg { zero, at, v0, v1, a0, a1, a2, a3, t0, t1, t2, t3, t4, t5, t6, t7, s0, s1, s2, s3, s4, s5, s6, s7, t8, t9, k0, k1, gp, sp, fp, ra, }; bool cps_pm_support_state(enum cps_pm_state state) { return test_bit(state, state_support); } static void coupled_barrier(atomic_t *a, unsigned online) { /* * This function is effectively the same as * cpuidle_coupled_parallel_barrier, which can't be used here since * there's no cpuidle device. */ if (!coupled_coherence) return; smp_mb__before_atomic(); atomic_inc(a); while (atomic_read(a) < online) cpu_relax(); if (atomic_inc_return(a) == online * 2) { atomic_set(a, 0); return; } while (atomic_read(a) > online) cpu_relax(); } int cps_pm_enter_state(enum cps_pm_state state) { unsigned cpu = smp_processor_id(); unsigned core = cpu_core(¤t_cpu_data); unsigned online, left; cpumask_t *coupled_mask = this_cpu_ptr(&online_coupled); u32 *core_ready_count, *nc_core_ready_count; void *nc_addr; cps_nc_entry_fn entry; struct core_boot_config *core_cfg; struct vpe_boot_config *vpe_cfg; /* Check that there is an entry function for this state */ entry = per_cpu(nc_asm_enter, core)[state]; if (!entry) return -EINVAL; /* Calculate which coupled CPUs (VPEs) are online */ #if defined(CONFIG_MIPS_MT) || defined(CONFIG_CPU_MIPSR6) if (cpu_online(cpu)) { cpumask_and(coupled_mask, cpu_online_mask, &cpu_sibling_map[cpu]); online = cpumask_weight(coupled_mask); cpumask_clear_cpu(cpu, coupled_mask); } else #endif { cpumask_clear(coupled_mask); online = 1; } /* Setup the VPE to run mips_cps_pm_restore when started again */ if (IS_ENABLED(CONFIG_CPU_PM) && state == CPS_PM_POWER_GATED) { /* Power gating relies upon CPS SMP */ if (!mips_cps_smp_in_use()) return -EINVAL; core_cfg = &mips_cps_core_bootcfg[core]; vpe_cfg = &core_cfg->vpe_config[cpu_vpe_id(¤t_cpu_data)]; vpe_cfg->pc = (unsigned long)mips_cps_pm_restore; vpe_cfg->gp = (unsigned long)current_thread_info(); vpe_cfg->sp = 0; } /* Indicate that this CPU might not be coherent */ cpumask_clear_cpu(cpu, &cpu_coherent_mask); smp_mb__after_atomic(); /* Create a non-coherent mapping of the core ready_count */ core_ready_count = per_cpu(ready_count, core); nc_addr = kmap_noncoherent(virt_to_page(core_ready_count), (unsigned long)core_ready_count); nc_addr += ((unsigned long)core_ready_count & ~PAGE_MASK); nc_core_ready_count = nc_addr; /* Ensure ready_count is zero-initialised before the assembly runs */ WRITE_ONCE(*nc_core_ready_count, 0); coupled_barrier(&per_cpu(pm_barrier, core), online); /* Run the generated entry code */ left = entry(online, nc_core_ready_count); /* Remove the non-coherent mapping of ready_count */ kunmap_noncoherent(); /* Indicate that this CPU is definitely coherent */ cpumask_set_cpu(cpu, &cpu_coherent_mask); /* * If this VPE is the first to leave the non-coherent wait state then * it needs to wake up any coupled VPEs still running their wait * instruction so that they return to cpuidle, which can then complete * coordination between the coupled VPEs & provide the governor with * a chance to reflect on the length of time the VPEs were in the * idle state. */ if (coupled_coherence && (state == CPS_PM_NC_WAIT) && (left == online)) arch_send_call_function_ipi_mask(coupled_mask); return 0; } static void cps_gen_cache_routine(u32 **pp, struct uasm_label **pl, struct uasm_reloc **pr, const struct cache_desc *cache, unsigned op, int lbl) { unsigned cache_size = cache->ways << cache->waybit; unsigned i; const unsigned unroll_lines = 32; /* If the cache isn't present this function has it easy */ if (cache->flags & MIPS_CACHE_NOT_PRESENT) return; /* Load base address */ UASM_i_LA(pp, t0, (long)CKSEG0); /* Calculate end address */ if (cache_size < 0x8000) uasm_i_addiu(pp, t1, t0, cache_size); else UASM_i_LA(pp, t1, (long)(CKSEG0 + cache_size)); /* Start of cache op loop */ uasm_build_label(pl, *pp, lbl); /* Generate the cache ops */ for (i = 0; i < unroll_lines; i++) { if (cpu_has_mips_r6) { uasm_i_cache(pp, op, 0, t0); uasm_i_addiu(pp, t0, t0, cache->linesz); } else { uasm_i_cache(pp, op, i * cache->linesz, t0); } } if (!cpu_has_mips_r6) /* Update the base address */ uasm_i_addiu(pp, t0, t0, unroll_lines * cache->linesz); /* Loop if we haven't reached the end address yet */ uasm_il_bne(pp, pr, t0, t1, lbl); uasm_i_nop(pp); } static int cps_gen_flush_fsb(u32 **pp, struct uasm_label **pl, struct uasm_reloc **pr, const struct cpuinfo_mips *cpu_info, int lbl) { unsigned i, fsb_size = 8; unsigned num_loads = (fsb_size * 3) / 2; unsigned line_stride = 2; unsigned line_size = cpu_info->dcache.linesz; unsigned perf_counter, perf_event; unsigned revision = cpu_info->processor_id & PRID_REV_MASK; /* * Determine whether this CPU requires an FSB flush, and if so which * performance counter/event reflect stalls due to a full FSB. */ switch (__get_cpu_type(cpu_info->cputype)) { case CPU_INTERAPTIV: perf_counter = 1; perf_event = 51; break; case CPU_PROAPTIV: /* Newer proAptiv cores don't require this workaround */ if (revision >= PRID_REV_ENCODE_332(1, 1, 0)) return 0; /* On older ones it's unavailable */ return -1; default: /* Assume that the CPU does not need this workaround */ return 0; } /* * Ensure that the fill/store buffer (FSB) is not holding the results * of a prefetch, since if it is then the CPC sequencer may become * stuck in the D3 (ClrBus) state whilst entering a low power state. */ /* Preserve perf counter setup */ uasm_i_mfc0(pp, t2, 25, (perf_counter * 2) + 0); /* PerfCtlN */ uasm_i_mfc0(pp, t3, 25, (perf_counter * 2) + 1); /* PerfCntN */ /* Setup perf counter to count FSB full pipeline stalls */ uasm_i_addiu(pp, t0, zero, (perf_event << 5) | 0xf); uasm_i_mtc0(pp, t0, 25, (perf_counter * 2) + 0); /* PerfCtlN */ uasm_i_ehb(pp); uasm_i_mtc0(pp, zero, 25, (perf_counter * 2) + 1); /* PerfCntN */ uasm_i_ehb(pp); /* Base address for loads */ UASM_i_LA(pp, t0, (long)CKSEG0); /* Start of clear loop */ uasm_build_label(pl, *pp, lbl); /* Perform some loads to fill the FSB */ for (i = 0; i < num_loads; i++) uasm_i_lw(pp, zero, i * line_size * line_stride, t0); /* * Invalidate the new D-cache entries so that the cache will need * refilling (via the FSB) if the loop is executed again. */ for (i = 0; i < num_loads; i++) { uasm_i_cache(pp, Hit_Invalidate_D, i * line_size * line_stride, t0); uasm_i_cache(pp, Hit_Writeback_Inv_SD, i * line_size * line_stride, t0); } /* Barrier ensuring previous cache invalidates are complete */ uasm_i_sync(pp, STYPE_SYNC); uasm_i_ehb(pp); /* Check whether the pipeline stalled due to the FSB being full */ uasm_i_mfc0(pp, t1, 25, (perf_counter * 2) + 1); /* PerfCntN */ /* Loop if it didn't */ uasm_il_beqz(pp, pr, t1, lbl); uasm_i_nop(pp); /* Restore perf counter 1. The count may well now be wrong... */ uasm_i_mtc0(pp, t2, 25, (perf_counter * 2) + 0); /* PerfCtlN */ uasm_i_ehb(pp); uasm_i_mtc0(pp, t3, 25, (perf_counter * 2) + 1); /* PerfCntN */ uasm_i_ehb(pp); return 0; } static void cps_gen_set_top_bit(u32 **pp, struct uasm_label **pl, struct uasm_reloc **pr, unsigned r_addr, int lbl) { uasm_i_lui(pp, t0, uasm_rel_hi(0x80000000)); uasm_build_label(pl, *pp, lbl); uasm_i_ll(pp, t1, 0, r_addr); uasm_i_or(pp, t1, t1, t0); uasm_i_sc(pp, t1, 0, r_addr); uasm_il_beqz(pp, pr, t1, lbl); uasm_i_nop(pp); } static void *cps_gen_entry_code(unsigned cpu, enum cps_pm_state state) { struct uasm_label *l = labels; struct uasm_reloc *r = relocs; u32 *buf, *p; const unsigned r_online = a0; const unsigned r_nc_count = a1; const unsigned r_pcohctl = t7; const unsigned max_instrs = 256; unsigned cpc_cmd; int err; enum { lbl_incready = 1, lbl_poll_cont, lbl_secondary_hang, lbl_disable_coherence, lbl_flush_fsb, lbl_invicache, lbl_flushdcache, lbl_hang, lbl_set_cont, lbl_secondary_cont, lbl_decready, }; /* Allocate a buffer to hold the generated code */ p = buf = kcalloc(max_instrs, sizeof(u32), GFP_KERNEL); if (!buf) return NULL; /* Clear labels & relocs ready for (re)use */ memset(labels, 0, sizeof(labels)); memset(relocs, 0, sizeof(relocs)); if (IS_ENABLED(CONFIG_CPU_PM) && state == CPS_PM_POWER_GATED) { /* Power gating relies upon CPS SMP */ if (!mips_cps_smp_in_use()) goto out_err; /* * Save CPU state. Note the non-standard calling convention * with the return address placed in v0 to avoid clobbering * the ra register before it is saved. */ UASM_i_LA(&p, t0, (long)mips_cps_pm_save); uasm_i_jalr(&p, v0, t0); uasm_i_nop(&p); } /* * Load addresses of required CM & CPC registers. This is done early * because they're needed in both the enable & disable coherence steps * but in the coupled case the enable step will only run on one VPE. */ UASM_i_LA(&p, r_pcohctl, (long)addr_gcr_cl_coherence()); if (coupled_coherence) { /* Increment ready_count */ uasm_i_sync(&p, STYPE_SYNC_MB); uasm_build_label(&l, p, lbl_incready); uasm_i_ll(&p, t1, 0, r_nc_count); uasm_i_addiu(&p, t2, t1, 1); uasm_i_sc(&p, t2, 0, r_nc_count); uasm_il_beqz(&p, &r, t2, lbl_incready); uasm_i_addiu(&p, t1, t1, 1); /* Barrier ensuring all CPUs see the updated r_nc_count value */ uasm_i_sync(&p, STYPE_SYNC_MB); /* * If this is the last VPE to become ready for non-coherence * then it should branch below. */ uasm_il_beq(&p, &r, t1, r_online, lbl_disable_coherence); uasm_i_nop(&p); if (state < CPS_PM_POWER_GATED) { /* * Otherwise this is not the last VPE to become ready * for non-coherence. It needs to wait until coherence * has been disabled before proceeding, which it will do * by polling for the top bit of ready_count being set. */ uasm_i_addiu(&p, t1, zero, -1); uasm_build_label(&l, p, lbl_poll_cont); uasm_i_lw(&p, t0, 0, r_nc_count); uasm_il_bltz(&p, &r, t0, lbl_secondary_cont); uasm_i_ehb(&p); if (cpu_has_mipsmt) uasm_i_yield(&p, zero, t1); uasm_il_b(&p, &r, lbl_poll_cont); uasm_i_nop(&p); } else { /* * The core will lose power & this VPE will not continue * so it can simply halt here. */ if (cpu_has_mipsmt) { /* Halt the VPE via C0 tchalt register */ uasm_i_addiu(&p, t0, zero, TCHALT_H); uasm_i_mtc0(&p, t0, 2, 4); } else if (cpu_has_vp) { /* Halt the VP via the CPC VP_STOP register */ unsigned int vpe_id; vpe_id = cpu_vpe_id(&cpu_data[cpu]); uasm_i_addiu(&p, t0, zero, 1 << vpe_id); UASM_i_LA(&p, t1, (long)addr_cpc_cl_vp_stop()); uasm_i_sw(&p, t0, 0, t1); } else { BUG(); } uasm_build_label(&l, p, lbl_secondary_hang); uasm_il_b(&p, &r, lbl_secondary_hang); uasm_i_nop(&p); } } /* * This is the point of no return - this VPE will now proceed to * disable coherence. At this point we *must* be sure that no other * VPE within the core will interfere with the L1 dcache. */ uasm_build_label(&l, p, lbl_disable_coherence); /* Invalidate the L1 icache */ cps_gen_cache_routine(&p, &l, &r, &cpu_data[cpu].icache, Index_Invalidate_I, lbl_invicache); /* Writeback & invalidate the L1 dcache */ cps_gen_cache_routine(&p, &l, &r, &cpu_data[cpu].dcache, Index_Writeback_Inv_D, lbl_flushdcache); /* Barrier ensuring previous cache invalidates are complete */ uasm_i_sync(&p, STYPE_SYNC); uasm_i_ehb(&p); if (mips_cm_revision() < CM_REV_CM3) { /* * Disable all but self interventions. The load from COHCTL is * defined by the interAptiv & proAptiv SUMs as ensuring that the * operation resulting from the preceding store is complete. */ uasm_i_addiu(&p, t0, zero, 1 << cpu_core(&cpu_data[cpu])); uasm_i_sw(&p, t0, 0, r_pcohctl); uasm_i_lw(&p, t0, 0, r_pcohctl); /* Barrier to ensure write to coherence control is complete */ uasm_i_sync(&p, STYPE_SYNC); uasm_i_ehb(&p); } /* Disable coherence */ uasm_i_sw(&p, zero, 0, r_pcohctl); uasm_i_lw(&p, t0, 0, r_pcohctl); if (state >= CPS_PM_CLOCK_GATED) { err = cps_gen_flush_fsb(&p, &l, &r, &cpu_data[cpu], lbl_flush_fsb); if (err) goto out_err; /* Determine the CPC command to issue */ switch (state) { case CPS_PM_CLOCK_GATED: cpc_cmd = CPC_Cx_CMD_CLOCKOFF; break; case CPS_PM_POWER_GATED: cpc_cmd = CPC_Cx_CMD_PWRDOWN; break; default: BUG(); goto out_err; } /* Issue the CPC command */ UASM_i_LA(&p, t0, (long)addr_cpc_cl_cmd()); uasm_i_addiu(&p, t1, zero, cpc_cmd); uasm_i_sw(&p, t1, 0, t0); if (state == CPS_PM_POWER_GATED) { /* If anything goes wrong just hang */ uasm_build_label(&l, p, lbl_hang); uasm_il_b(&p, &r, lbl_hang); uasm_i_nop(&p); /* * There's no point generating more code, the core is * powered down & if powered back up will run from the * reset vector not from here. */ goto gen_done; } /* Barrier to ensure write to CPC command is complete */ uasm_i_sync(&p, STYPE_SYNC); uasm_i_ehb(&p); } if (state == CPS_PM_NC_WAIT) { /* * At this point it is safe for all VPEs to proceed with * execution. This VPE will set the top bit of ready_count * to indicate to the other VPEs that they may continue. */ if (coupled_coherence) cps_gen_set_top_bit(&p, &l, &r, r_nc_count, lbl_set_cont); /* * VPEs which did not disable coherence will continue * executing, after coherence has been disabled, from this * point. */ uasm_build_label(&l, p, lbl_secondary_cont); /* Now perform our wait */ uasm_i_wait(&p, 0); } /* * Re-enable coherence. Note that for CPS_PM_NC_WAIT all coupled VPEs * will run this. The first will actually re-enable coherence & the * rest will just be performing a rather unusual nop. */ uasm_i_addiu(&p, t0, zero, mips_cm_revision() < CM_REV_CM3 ? CM_GCR_Cx_COHERENCE_COHDOMAINEN : CM3_GCR_Cx_COHERENCE_COHEN); uasm_i_sw(&p, t0, 0, r_pcohctl); uasm_i_lw(&p, t0, 0, r_pcohctl); /* Barrier to ensure write to coherence control is complete */ uasm_i_sync(&p, STYPE_SYNC); uasm_i_ehb(&p); if (coupled_coherence && (state == CPS_PM_NC_WAIT)) { /* Decrement ready_count */ uasm_build_label(&l, p, lbl_decready); uasm_i_sync(&p, STYPE_SYNC_MB); uasm_i_ll(&p, t1, 0, r_nc_count); uasm_i_addiu(&p, t2, t1, -1); uasm_i_sc(&p, t2, 0, r_nc_count); uasm_il_beqz(&p, &r, t2, lbl_decready); uasm_i_andi(&p, v0, t1, (1 << fls(smp_num_siblings)) - 1); /* Barrier ensuring all CPUs see the updated r_nc_count value */ uasm_i_sync(&p, STYPE_SYNC_MB); } if (coupled_coherence && (state == CPS_PM_CLOCK_GATED)) { /* * At this point it is safe for all VPEs to proceed with * execution. This VPE will set the top bit of ready_count * to indicate to the other VPEs that they may continue. */ cps_gen_set_top_bit(&p, &l, &r, r_nc_count, lbl_set_cont); /* * This core will be reliant upon another core sending a * power-up command to the CPC in order to resume operation. * Thus an arbitrary VPE can't trigger the core leaving the * idle state and the one that disables coherence might as well * be the one to re-enable it. The rest will continue from here * after that has been done. */ uasm_build_label(&l, p, lbl_secondary_cont); /* Barrier ensuring all CPUs see the updated r_nc_count value */ uasm_i_sync(&p, STYPE_SYNC_MB); } /* The core is coherent, time to return to C code */ uasm_i_jr(&p, ra); uasm_i_nop(&p); gen_done: /* Ensure the code didn't exceed the resources allocated for it */ BUG_ON((p - buf) > max_instrs); BUG_ON((l - labels) > ARRAY_SIZE(labels)); BUG_ON((r - relocs) > ARRAY_SIZE(relocs)); /* Patch branch offsets */ uasm_resolve_relocs(relocs, labels); /* Flush the icache */ local_flush_icache_range((unsigned long)buf, (unsigned long)p); return buf; out_err: kfree(buf); return NULL; } static int cps_pm_online_cpu(unsigned int cpu) { enum cps_pm_state state; unsigned core = cpu_core(&cpu_data[cpu]); void *entry_fn, *core_rc; for (state = CPS_PM_NC_WAIT; state < CPS_PM_STATE_COUNT; state++) { if (per_cpu(nc_asm_enter, core)[state]) continue; if (!test_bit(state, state_support)) continue; entry_fn = cps_gen_entry_code(cpu, state); if (!entry_fn) { pr_err("Failed to generate core %u state %u entry\n", core, state); clear_bit(state, state_support); } per_cpu(nc_asm_enter, core)[state] = entry_fn; } if (!per_cpu(ready_count, core)) { core_rc = kmalloc(sizeof(u32), GFP_KERNEL); if (!core_rc) { pr_err("Failed allocate core %u ready_count\n", core); return -ENOMEM; } per_cpu(ready_count, core) = core_rc; } return 0; } static int cps_pm_power_notifier(struct notifier_block *this, unsigned long event, void *ptr) { unsigned int stat; switch (event) { case PM_SUSPEND_PREPARE: stat = read_cpc_cl_stat_conf(); /* * If we're attempting to suspend the system and power down all * of the cores, the JTAG detect bit indicates that the CPC will * instead put the cores into clock-off state. In this state * a connected debugger can cause the CPU to attempt * interactions with the powered down system. At best this will * fail. At worst, it can hang the NoC, requiring a hard reset. * To avoid this, just block system suspend if a JTAG probe * is detected. */ if (stat & CPC_Cx_STAT_CONF_EJTAG_PROBE) { pr_warn("JTAG probe is connected - abort suspend\n"); return NOTIFY_BAD; } return NOTIFY_DONE; default: return NOTIFY_DONE; } } static int __init cps_pm_init(void) { /* A CM is required for all non-coherent states */ if (!mips_cm_present()) { pr_warn("pm-cps: no CM, non-coherent states unavailable\n"); return 0; } /* * If interrupts were enabled whilst running a wait instruction on a * non-coherent core then the VPE may end up processing interrupts * whilst non-coherent. That would be bad. */ if (cpu_wait == r4k_wait_irqoff) set_bit(CPS_PM_NC_WAIT, state_support); else pr_warn("pm-cps: non-coherent wait unavailable\n"); /* Detect whether a CPC is present */ if (mips_cpc_present()) { /* Detect whether clock gating is implemented */ if (read_cpc_cl_stat_conf() & CPC_Cx_STAT_CONF_CLKGAT_IMPL) set_bit(CPS_PM_CLOCK_GATED, state_support); else pr_warn("pm-cps: CPC does not support clock gating\n"); /* Power gating is available with CPS SMP & any CPC */ if (mips_cps_smp_in_use()) set_bit(CPS_PM_POWER_GATED, state_support); else pr_warn("pm-cps: CPS SMP not in use, power gating unavailable\n"); } else { pr_warn("pm-cps: no CPC, clock & power gating unavailable\n"); } pm_notifier(cps_pm_power_notifier, 0); return cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mips/cps_pm:online", cps_pm_online_cpu, NULL); } arch_initcall(cps_pm_init);