1 files changed, 619 insertions, 0 deletions

diff --git a/arch/mips/kernel/smp-cps.c b/arch/mips/kernel/smp-cps.c
new file mode 100644
index 000000000..03f1026ad
--- /dev/null
+++ b/arch/mips/kernel/smp-cps.c
@@ -0,0 +1,619 @@
+/*
+ * Copyright (C) 2013 Imagination Technologies
+ * Author: Paul Burton <paul.burton@mips.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/cpu.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/sched/task_stack.h>
+#include <linux/sched/hotplug.h>
+#include <linux/slab.h>
+#include <linux/smp.h>
+#include <linux/types.h>
+
+#include <asm/bcache.h>
+#include <asm/mips-cps.h>
+#include <asm/mips_mt.h>
+#include <asm/mipsregs.h>
+#include <asm/pm-cps.h>
+#include <asm/r4kcache.h>
+#include <asm/smp-cps.h>
+#include <asm/time.h>
+#include <asm/uasm.h>
+
+static bool threads_disabled;
+static DECLARE_BITMAP(core_power, NR_CPUS);
+
+struct core_boot_config *mips_cps_core_bootcfg;
+
+static int __init setup_nothreads(char *s)
+{
+	threads_disabled = true;
+	return 0;
+}
+early_param("nothreads", setup_nothreads);
+
+static unsigned core_vpe_count(unsigned int cluster, unsigned core)
+{
+	if (threads_disabled)
+		return 1;
+
+	return mips_cps_numvps(cluster, core);
+}
+
+static void __init cps_smp_setup(void)
+{
+	unsigned int nclusters, ncores, nvpes, core_vpes;
+	unsigned long core_entry;
+	int cl, c, v;
+
+	/* Detect & record VPE topology */
+	nvpes = 0;
+	nclusters = mips_cps_numclusters();
+	pr_info("%s topology ", cpu_has_mips_r6 ? "VP" : "VPE");
+	for (cl = 0; cl < nclusters; cl++) {
+		if (cl > 0)
+			pr_cont(",");
+		pr_cont("{");
+
+		ncores = mips_cps_numcores(cl);
+		for (c = 0; c < ncores; c++) {
+			core_vpes = core_vpe_count(cl, c);
+
+			if (c > 0)
+				pr_cont(",");
+			pr_cont("%u", core_vpes);
+
+			/* Use the number of VPEs in cluster 0 core 0 for smp_num_siblings */
+			if (!cl && !c)
+				smp_num_siblings = core_vpes;
+
+			for (v = 0; v < min_t(int, core_vpes, NR_CPUS - nvpes); v++) {
+				cpu_set_cluster(&cpu_data[nvpes + v], cl);
+				cpu_set_core(&cpu_data[nvpes + v], c);
+				cpu_set_vpe_id(&cpu_data[nvpes + v], v);
+			}
+
+			nvpes += core_vpes;
+		}
+
+		pr_cont("}");
+	}
+	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, cpu_cluster(&cpu_data[v]) == 0);
+		set_cpu_present(v, cpu_cluster(&cpu_data[v]) == 0);
+		__cpu_number_map[v] = v;
+		__cpu_logical_map[v] = v;
+	}
+
+	/* Set a coherent default CCA (CWB) */
+	change_c0_config(CONF_CM_CMASK, 0x5);
+
+	/* Core 0 is powered up (we're running on it) */
+	bitmap_set(core_power, 0, 1);
+
+	/* Initialise core 0 */
+	mips_cps_core_init();
+
+	/* Make core 0 coherent with everything */
+	write_gcr_cl_coherence(0xff);
+
+	if (mips_cm_revision() >= CM_REV_CM3) {
+		core_entry = CKSEG1ADDR((unsigned long)mips_cps_core_entry);
+		write_gcr_bev_base(core_entry);
+	}
+
+#ifdef CONFIG_MIPS_MT_FPAFF
+	/* If we have an FPU, enroll ourselves in the FPU-full mask */
+	if (cpu_has_fpu)
+		cpumask_set_cpu(0, &mt_fpu_cpumask);
+#endif /* CONFIG_MIPS_MT_FPAFF */
+}
+
+static void __init cps_prepare_cpus(unsigned int max_cpus)
+{
+	unsigned ncores, core_vpes, c, cca;
+	bool cca_unsuitable, cores_limited;
+	u32 *entry_code;
+
+	mips_mt_set_cpuoptions();
+
+	/* Detect whether the CCA is unsuited to multi-core SMP */
+	cca = read_c0_config() & CONF_CM_CMASK;
+	switch (cca) {
+	case 0x4: /* CWBE */
+	case 0x5: /* CWB */
+		/* The CCA is coherent, multi-core is fine */
+		cca_unsuitable = false;
+		break;
+
+	default:
+		/* CCA is not coherent, multi-core is not usable */
+		cca_unsuitable = true;
+	}
+
+	/* Warn the user if the CCA prevents multi-core */
+	cores_limited = false;
+	if (cca_unsuitable || cpu_has_dc_aliases) {
+		for_each_present_cpu(c) {
+			if (cpus_are_siblings(smp_processor_id(), c))
+				continue;
+
+			set_cpu_present(c, false);
+			cores_limited = true;
+		}
+	}
+	if (cores_limited)
+		pr_warn("Using only one core due to %s%s%s\n",
+			cca_unsuitable ? "unsuitable CCA" : "",
+			(cca_unsuitable && cpu_has_dc_aliases) ? " & " : "",
+			cpu_has_dc_aliases ? "dcache aliasing" : "");
+
+	/*
+	 * Patch the start of mips_cps_core_entry to provide:
+	 *
+	 * s0 = kseg0 CCA
+	 */
+	entry_code = (u32 *)&mips_cps_core_entry;
+	uasm_i_addiu(&entry_code, 16, 0, cca);
+	blast_dcache_range((unsigned long)&mips_cps_core_entry,
+			   (unsigned long)entry_code);
+	bc_wback_inv((unsigned long)&mips_cps_core_entry,
+		     (void *)entry_code - (void *)&mips_cps_core_entry);
+	__sync();
+
+	/* Allocate core boot configuration structs */
+	ncores = mips_cps_numcores(0);
+	mips_cps_core_bootcfg = kcalloc(ncores, sizeof(*mips_cps_core_bootcfg),
+					GFP_KERNEL);
+	if (!mips_cps_core_bootcfg) {
+		pr_err("Failed to allocate boot config for %u cores\n", ncores);
+		goto err_out;
+	}
+
+	/* Allocate VPE boot configuration structs */
+	for (c = 0; c < ncores; c++) {
+		core_vpes = core_vpe_count(0, c);
+		mips_cps_core_bootcfg[c].vpe_config = kcalloc(core_vpes,
+				sizeof(*mips_cps_core_bootcfg[c].vpe_config),
+				GFP_KERNEL);
+		if (!mips_cps_core_bootcfg[c].vpe_config) {
+			pr_err("Failed to allocate %u VPE boot configs\n",
+			       core_vpes);
+			goto err_out;
+		}
+	}
+
+	/* Mark this CPU as booted */
+	atomic_set(&mips_cps_core_bootcfg[cpu_core(&current_cpu_data)].vpe_mask,
+		   1 << cpu_vpe_id(&current_cpu_data));
+
+	return;
+err_out:
+	/* Clean up allocations */
+	if (mips_cps_core_bootcfg) {
+		for (c = 0; c < ncores; c++)
+			kfree(mips_cps_core_bootcfg[c].vpe_config);
+		kfree(mips_cps_core_bootcfg);
+		mips_cps_core_bootcfg = NULL;
+	}
+
+	/* Effectively disable SMP by declaring CPUs not present */
+	for_each_possible_cpu(c) {
+		if (c == 0)
+			continue;
+		set_cpu_present(c, false);
+	}
+}
+
+static void boot_core(unsigned int core, unsigned int vpe_id)
+{
+	u32 stat, seq_state;
+	unsigned timeout;
+
+	/* Select the appropriate core */
+	mips_cm_lock_other(0, core, 0, CM_GCR_Cx_OTHER_BLOCK_LOCAL);
+
+	/* 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);
+
+	/* Start it with the legacy memory map and exception base */
+	write_gcr_co_reset_ext_base(CM_GCR_Cx_RESET_EXT_BASE_UEB);
+
+	/* Ensure the core can access the GCRs */
+	set_gcr_access(1 << core);
+
+	if (mips_cpc_present()) {
+		/* Reset the core */
+		mips_cpc_lock_other(core);
+
+		if (mips_cm_revision() >= CM_REV_CM3) {
+			/* Run only the requested VP following the reset */
+			write_cpc_co_vp_stop(0xf);
+			write_cpc_co_vp_run(1 << vpe_id);
+
+			/*
+			 * Ensure that the VP_RUN register is written before the
+			 * core leaves reset.
+			 */
+			wmb();
+		}
+
+		write_cpc_co_cmd(CPC_Cx_CMD_RESET);
+
+		timeout = 100;
+		while (true) {
+			stat = read_cpc_co_stat_conf();
+			seq_state = stat & CPC_Cx_STAT_CONF_SEQSTATE;
+			seq_state >>= __ffs(CPC_Cx_STAT_CONF_SEQSTATE);
+
+			/* U6 == coherent execution, ie. the core is up */
+			if (seq_state == CPC_Cx_STAT_CONF_SEQSTATE_U6)
+				break;
+
+			/* Delay a little while before we start warning */
+			if (timeout) {
+				timeout--;
+				mdelay(10);
+				continue;
+			}
+
+			pr_warn("Waiting for core %u to start... STAT_CONF=0x%x\n",
+				core, stat);
+			mdelay(1000);
+		}
+
+		mips_cpc_unlock_other();
+	} else {
+		/* Take the core out of reset */
+		write_gcr_co_reset_release(0);
+	}
+
+	mips_cm_unlock_other();
+
+	/* The core is now powered up */
+	bitmap_set(core_power, core, 1);
+}
+
+static void remote_vpe_boot(void *dummy)
+{
+	unsigned core = cpu_core(&current_cpu_data);
+	struct core_boot_config *core_cfg = &mips_cps_core_bootcfg[core];
+
+	mips_cps_boot_vpes(core_cfg, cpu_vpe_id(&current_cpu_data));
+}
+
+static int cps_boot_secondary(int cpu, struct task_struct *idle)
+{
+	unsigned core = cpu_core(&cpu_data[cpu]);
+	unsigned vpe_id = cpu_vpe_id(&cpu_data[cpu]);
+	struct core_boot_config *core_cfg = &mips_cps_core_bootcfg[core];
+	struct vpe_boot_config *vpe_cfg = &core_cfg->vpe_config[vpe_id];
+	unsigned long core_entry;
+	unsigned int remote;
+	int err;
+
+	/* We don't yet support booting CPUs in other clusters */
+	if (cpu_cluster(&cpu_data[cpu]) != cpu_cluster(&raw_current_cpu_data))
+		return -ENOSYS;
+
+	vpe_cfg->pc = (unsigned long)&smp_bootstrap;
+	vpe_cfg->sp = __KSTK_TOS(idle);
+	vpe_cfg->gp = (unsigned long)task_thread_info(idle);
+
+	atomic_or(1 << cpu_vpe_id(&cpu_data[cpu]), &core_cfg->vpe_mask);
+
+	preempt_disable();
+
+	if (!test_bit(core, core_power)) {
+		/* Boot a VPE on a powered down core */
+		boot_core(core, vpe_id);
+		goto out;
+	}
+
+	if (cpu_has_vp) {
+		mips_cm_lock_other(0, core, vpe_id, CM_GCR_Cx_OTHER_BLOCK_LOCAL);
+		core_entry = CKSEG1ADDR((unsigned long)mips_cps_core_entry);
+		write_gcr_co_reset_base(core_entry);
+		mips_cm_unlock_other();
+	}
+
+	if (!cpus_are_siblings(cpu, smp_processor_id())) {
+		/* Boot a VPE on another powered up core */
+		for (remote = 0; remote < NR_CPUS; remote++) {
+			if (!cpus_are_siblings(cpu, remote))
+				continue;
+			if (cpu_online(remote))
+				break;
+		}
+		if (remote >= NR_CPUS) {
+			pr_crit("No online CPU in core %u to start CPU%d\n",
+				core, cpu);
+			goto out;
+		}
+
+		err = smp_call_function_single(remote, remote_vpe_boot,
+					       NULL, 1);
+		if (err)
+			panic("Failed to call remote CPU\n");
+		goto out;
+	}
+
+	BUG_ON(!cpu_has_mipsmt && !cpu_has_vp);
+
+	/* Boot a VPE on this core */
+	mips_cps_boot_vpes(core_cfg, vpe_id);
+out:
+	preempt_enable();
+	return 0;
+}
+
+static void cps_init_secondary(void)
+{
+	/* Disable MT - we only want to run 1 TC per VPE */
+	if (cpu_has_mipsmt)
+		dmt();
+
+	if (mips_cm_revision() >= CM_REV_CM3) {
+		unsigned int ident = read_gic_vl_ident();
+
+		/*
+		 * Ensure that our calculation of the VP ID matches up with
+		 * what the GIC reports, otherwise we'll have configured
+		 * interrupts incorrectly.
+		 */
+		BUG_ON(ident != mips_cm_vp_id(smp_processor_id()));
+	}
+
+	if (cpu_has_veic)
+		clear_c0_status(ST0_IM);
+	else
+		change_c0_status(ST0_IM, STATUSF_IP2 | STATUSF_IP3 |
+					 STATUSF_IP4 | STATUSF_IP5 |
+					 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)
+		cpumask_set_cpu(smp_processor_id(), &mt_fpu_cpumask);
+#endif /* CONFIG_MIPS_MT_FPAFF */
+
+	local_irq_enable();
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+static int cps_cpu_disable(void)
+{
+	unsigned cpu = smp_processor_id();
+	struct core_boot_config *core_cfg;
+
+	if (!cpu)
+		return -EBUSY;
+
+	if (!cps_pm_support_state(CPS_PM_POWER_GATED))
+		return -EINVAL;
+
+	core_cfg = &mips_cps_core_bootcfg[cpu_core(&current_cpu_data)];
+	atomic_sub(1 << cpu_vpe_id(&current_cpu_data), &core_cfg->vpe_mask);
+	smp_mb__after_atomic();
+	set_cpu_online(cpu, false);
+	calculate_cpu_foreign_map();
+
+	return 0;
+}
+
+static unsigned cpu_death_sibling;
+static enum {
+	CPU_DEATH_HALT,
+	CPU_DEATH_POWER,
+} cpu_death;
+
+void play_dead(void)
+{
+	unsigned int cpu, core, vpe_id;
+
+	local_irq_disable();
+	idle_task_exit();
+	cpu = smp_processor_id();
+	core = cpu_core(&cpu_data[cpu]);
+	cpu_death = CPU_DEATH_POWER;
+
+	pr_debug("CPU%d going offline\n", cpu);
+
+	if (cpu_has_mipsmt || cpu_has_vp) {
+		/* Look for another online VPE within the core */
+		for_each_online_cpu(cpu_death_sibling) {
+			if (!cpus_are_siblings(cpu, cpu_death_sibling))
+				continue;
+
+			/*
+			 * There is an online VPE within the core. Just halt
+			 * this TC and leave the core alone.
+			 */
+			cpu_death = CPU_DEATH_HALT;
+			break;
+		}
+	}
+
+	/* This CPU has chosen its way out */
+	(void)cpu_report_death();
+
+	if (cpu_death == CPU_DEATH_HALT) {
+		vpe_id = cpu_vpe_id(&cpu_data[cpu]);
+
+		pr_debug("Halting core %d VP%d\n", core, vpe_id);
+		if (cpu_has_mipsmt) {
+			/* Halt this TC */
+			write_c0_tchalt(TCHALT_H);
+			instruction_hazard();
+		} else if (cpu_has_vp) {
+			write_cpc_cl_vp_stop(1 << vpe_id);
+
+			/* Ensure that the VP_STOP register is written */
+			wmb();
+		}
+	} else {
+		pr_debug("Gating power to core %d\n", core);
+		/* Power down the core */
+		cps_pm_enter_state(CPS_PM_POWER_GATED);
+	}
+
+	/* This should never be reached */
+	panic("Failed to offline CPU %u", cpu);
+}
+
+static void wait_for_sibling_halt(void *ptr_cpu)
+{
+	unsigned cpu = (unsigned long)ptr_cpu;
+	unsigned vpe_id = cpu_vpe_id(&cpu_data[cpu]);
+	unsigned halted;
+	unsigned long flags;
+
+	do {
+		local_irq_save(flags);
+		settc(vpe_id);
+		halted = read_tc_c0_tchalt();
+		local_irq_restore(flags);
+	} while (!(halted & TCHALT_H));
+}
+
+static void cps_cpu_die(unsigned int cpu)
+{
+	unsigned core = cpu_core(&cpu_data[cpu]);
+	unsigned int vpe_id = cpu_vpe_id(&cpu_data[cpu]);
+	ktime_t fail_time;
+	unsigned stat;
+	int err;
+
+	/* Wait for the cpu to choose its way out */
+	if (!cpu_wait_death(cpu, 5)) {
+		pr_err("CPU%u: didn't offline\n", cpu);
+		return;
+	}
+
+	/*
+	 * Now wait for the CPU to actually offline. Without doing this that
+	 * offlining may race with one or more of:
+	 *
+	 *   - Onlining the CPU again.
+	 *   - Powering down the core if another VPE within it is offlined.
+	 *   - A sibling VPE entering a non-coherent state.
+	 *
+	 * In the non-MT halt case (ie. infinite loop) the CPU is doing nothing
+	 * with which we could race, so do nothing.
+	 */
+	if (cpu_death == CPU_DEATH_POWER) {
+		/*
+		 * Wait for the core to enter a powered down or clock gated
+		 * state, the latter happening when a JTAG probe is connected
+		 * in which case the CPC will refuse to power down the core.
+		 */
+		fail_time = ktime_add_ms(ktime_get(), 2000);
+		do {
+			mips_cm_lock_other(0, core, 0, CM_GCR_Cx_OTHER_BLOCK_LOCAL);
+			mips_cpc_lock_other(core);
+			stat = read_cpc_co_stat_conf();
+			stat &= CPC_Cx_STAT_CONF_SEQSTATE;
+			stat >>= __ffs(CPC_Cx_STAT_CONF_SEQSTATE);
+			mips_cpc_unlock_other();
+			mips_cm_unlock_other();
+
+			if (stat == CPC_Cx_STAT_CONF_SEQSTATE_D0 ||
+			    stat == CPC_Cx_STAT_CONF_SEQSTATE_D2 ||
+			    stat == CPC_Cx_STAT_CONF_SEQSTATE_U2)
+				break;
+
+			/*
+			 * The core ought to have powered down, but didn't &
+			 * now we don't really know what state it's in. It's
+			 * likely that its _pwr_up pin has been wired to logic
+			 * 1 & it powered back up as soon as we powered it
+			 * down...
+			 *
+			 * The best we can do is warn the user & continue in
+			 * the hope that the core is doing nothing harmful &
+			 * might behave properly if we online it later.
+			 */
+			if (WARN(ktime_after(ktime_get(), fail_time),
+				 "CPU%u hasn't powered down, seq. state %u\n",
+				 cpu, stat))
+				break;
+		} while (1);
+
+		/* Indicate the core is powered off */
+		bitmap_clear(core_power, core, 1);
+	} else if (cpu_has_mipsmt) {
+		/*
+		 * Have a CPU with access to the offlined CPUs registers wait
+		 * for its TC to halt.
+		 */
+		err = smp_call_function_single(cpu_death_sibling,
+					       wait_for_sibling_halt,
+					       (void *)(unsigned long)cpu, 1);
+		if (err)
+			panic("Failed to call remote sibling CPU\n");
+	} else if (cpu_has_vp) {
+		do {
+			mips_cm_lock_other(0, core, vpe_id, CM_GCR_Cx_OTHER_BLOCK_LOCAL);
+			stat = read_cpc_co_vp_running();
+			mips_cm_unlock_other();
+		} while (stat & (1 << vpe_id));
+	}
+}
+
+#endif /* CONFIG_HOTPLUG_CPU */
+
+static const 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	= mips_smp_send_ipi_single,
+	.send_ipi_mask		= mips_smp_send_ipi_mask,
+#ifdef CONFIG_HOTPLUG_CPU
+	.cpu_disable		= cps_cpu_disable,
+	.cpu_die		= cps_cpu_die,
+#endif
+};
+
+bool mips_cps_smp_in_use(void)
+{
+	extern const struct plat_smp_ops *mp_ops;
+	return mp_ops == &cps_smp_ops;
+}
+
+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)) {
+		pr_warn("MIPS CPS SMP unable to proceed without a GIC\n");
+		return -ENODEV;
+	}
+
+	register_smp_ops(&cps_smp_ops);
+	return 0;
+}