1 files changed, 466 insertions, 0 deletions
diff --git a/arch/mips/kernel/smp-cps.c b/arch/mips/kernel/smp-cps.c
new file mode 100644
index 00000000000..949f2c6827a
--- /dev/null
+++ b/arch/mips/kernel/smp-cps.c
@@ -0,0 +1,466 @@
+/*
+ * 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/pm-cps.h>
+#include <asm/smp-cps.h>
+#include <asm/time.h>
+#include <asm/uasm.h>
+
+static DECLARE_BITMAP(core_power, NR_CPUS);
+
+struct core_boot_config *mips_cps_core_bootcfg;
+
+static unsigned core_vpe_count(unsigned core)
+{
+	unsigned cfg;
+
+	if (!config_enabled(CONFIG_MIPS_MT_SMP) || !cpu_has_mipsmt)
+		return 1;
+
+	write_gcr_cl_other(core << CM_GCR_Cx_OTHER_CORENUM_SHF);
+	cfg = read_gcr_co_config() & CM_GCR_Cx_CONFIG_PVPE_MSK;
+	return (cfg >> CM_GCR_Cx_CONFIG_PVPE_SHF) + 1;
+}
+
+static void __init cps_smp_setup(void)
+{
+	unsigned int ncores, nvpes, core_vpes;
+	int c, v;
+
+	/* Detect & record VPE topology */
+	ncores = mips_cm_numcores();
+	pr_info("VPE topology ");
+	for (c = nvpes = 0; c < ncores; c++) {
+		core_vpes = core_vpe_count(c);
+		pr_cont("%c%u", c ? ',' : '{', core_vpes);
+
+		/* Use the number of VPEs in core 0 for smp_num_siblings */
+		if (!c)
+			smp_num_siblings = 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;
+	}
+
+	/* 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);
+}
+
+static void __init cps_prepare_cpus(unsigned int max_cpus)
+{
+	unsigned ncores, core_vpes, c, cca;
+	bool cca_unsuitable;
+	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 */
+	ncores = mips_cm_numcores();
+	if (cca_unsuitable && ncores > 1) {
+		pr_warn("Using only one core due to unsuitable CCA 0x%x\n",
+			cca);
+
+		for_each_present_cpu(c) {
+			if (cpu_data[c].core)
+				set_cpu_present(c, false);
+		}
+	}
+
+	/*
+	 * Patch the start of mips_cps_core_entry to provide:
+	 *
+	 * v0 = CM base address
+	 * s0 = kseg0 CCA
+	 */
+	entry_code = (u32 *)&mips_cps_core_entry;
+	UASM_i_LA(&entry_code, 3, (long)mips_cm_base);
+	uasm_i_addiu(&entry_code, 16, 0, cca);
+	dma_cache_wback_inv((unsigned long)&mips_cps_core_entry,
+			    (void *)entry_code - (void *)&mips_cps_core_entry);
+
+	/* Allocate core boot configuration structs */
+	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(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[current_cpu_data.core].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 core)
+{
+	u32 access;
+
+	/* Select the appropriate core */
+	write_gcr_cl_other(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 + core);
+	write_gcr_access(access);
+
+	if (mips_cpc_present()) {
+		/* Reset the core */
+		mips_cpc_lock_other(core);
+		write_cpc_co_cmd(CPC_Cx_CMD_RESET);
+		mips_cpc_unlock_other();
+	} else {
+		/* Take the core out of reset */
+		write_gcr_co_reset_release(0);
+	}
+
+	/* The core is now powered up */
+	bitmap_set(core_power, core, 1);
+}
+
+static void remote_vpe_boot(void *dummy)
+{
+	mips_cps_boot_vpes();
+}
+
+static void cps_boot_secondary(int cpu, struct task_struct *idle)
+{
+	unsigned core = cpu_data[cpu].core;
+	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 int remote;
+	int err;
+
+	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);
+		goto out;
+	}
+
+	if (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 != core)
+				continue;
+			if (cpu_online(remote))
+				break;
+		}
+		BUG_ON(remote >= NR_CPUS);
+
+		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);
+
+	/* Boot a VPE on this core */
+	mips_cps_boot_vpes();
+out:
+	preempt_enable();
+}
+
+static void cps_init_secondary(void)
+{
+	/* Disable MT - we only want to run 1 TC per VPE */
+	if (cpu_has_mipsmt)
+		dmt();
+
+	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();
+}
+
+#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[current_cpu_data.core];
+	atomic_sub(1 << cpu_vpe_id(&current_cpu_data), &core_cfg->vpe_mask);
+	smp_mb__after_atomic();
+	set_cpu_online(cpu, false);
+	cpu_clear(cpu, cpu_callin_map);
+
+	return 0;
+}
+
+static DECLARE_COMPLETION(cpu_death_chosen);
+static unsigned cpu_death_sibling;
+static enum {
+	CPU_DEATH_HALT,
+	CPU_DEATH_POWER,
+} cpu_death;
+
+void play_dead(void)
+{
+	unsigned cpu, core;
+
+	local_irq_disable();
+	idle_task_exit();
+	cpu = smp_processor_id();
+	cpu_death = CPU_DEATH_POWER;
+
+	if (cpu_has_mipsmt) {
+		core = cpu_data[cpu].core;
+
+		/* Look for another online VPE within the core */
+		for_each_online_cpu(cpu_death_sibling) {
+			if (cpu_data[cpu_death_sibling].core != core)
+				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 */
+	complete(&cpu_death_chosen);
+
+	if (cpu_death == CPU_DEATH_HALT) {
+		/* Halt this TC */
+		write_c0_tchalt(TCHALT_H);
+		instruction_hazard();
+	} else {
+		/* 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)ptr_cpu;
+	unsigned vpe_id = cpu_data[cpu].vpe_id;
+	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_data[cpu].core;
+	unsigned stat;
+	int err;
+
+	/* Wait for the cpu to choose its way out */
+	if (!wait_for_completion_timeout(&cpu_death_chosen,
+					 msecs_to_jiffies(5000))) {
+		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.
+		 */
+		do {
+			mips_cpc_lock_other(core);
+			stat = read_cpc_co_stat_conf();
+			stat &= CPC_Cx_STAT_CONF_SEQSTATE_MSK;
+			mips_cpc_unlock_other();
+		} while (stat != CPC_Cx_STAT_CONF_SEQSTATE_D0 &&
+			 stat != CPC_Cx_STAT_CONF_SEQSTATE_D2 &&
+			 stat != CPC_Cx_STAT_CONF_SEQSTATE_U2);
+
+		/* 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 *)cpu, 1);
+		if (err)
+			panic("Failed to call remote sibling CPU\n");
+	}
+}
+
+#endif /* CONFIG_HOTPLUG_CPU */
+
+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,
+#ifdef CONFIG_HOTPLUG_CPU
+	.cpu_disable		= cps_cpu_disable,
+	.cpu_die		= cps_cpu_die,
+#endif
+};
+
+bool mips_cps_smp_in_use(void)
+{
+	extern 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_MSK)) {
+		pr_warn("MIPS CPS SMP unable to proceed without a GIC\n");
+		return -ENODEV;
+	}
+
+	register_smp_ops(&cps_smp_ops);
+	return 0;
+}