1 files changed, 356 insertions, 0 deletions
diff --git a/arch/arc/kernel/mcip.c b/arch/arc/kernel/mcip.c
new file mode 100644
index 000000000..2fb865890
--- /dev/null
+++ b/arch/arc/kernel/mcip.c
@@ -0,0 +1,356 @@
+/*
+ * ARC ARConnect (MultiCore IP) support (formerly known as MCIP)
+ *
+ * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/smp.h>
+#include <linux/irq.h>
+#include <linux/spinlock.h>
+#include <asm/mcip.h>
+
+static char smp_cpuinfo_buf[128];
+static int idu_detected;
+
+static DEFINE_RAW_SPINLOCK(mcip_lock);
+
+/*
+ * Any SMP specific init any CPU does when it comes up.
+ * Here we setup the CPU to enable Inter-Processor-Interrupts
+ * Called for each CPU
+ * -Master      : init_IRQ()
+ * -Other(s)    : start_kernel_secondary()
+ */
+void mcip_init_smp(unsigned int cpu)
+{
+	smp_ipi_irq_setup(cpu, IPI_IRQ);
+}
+
+static void mcip_ipi_send(int cpu)
+{
+	unsigned long flags;
+	int ipi_was_pending;
+
+	/*
+	 * NOTE: We must spin here if the other cpu hasn't yet
+	 * serviced a previous message. This can burn lots
+	 * of time, but we MUST follows this protocol or
+	 * ipi messages can be lost!!!
+	 * Also, we must release the lock in this loop because
+	 * the other side may get to this same loop and not
+	 * be able to ack -- thus causing deadlock.
+	 */
+
+	do {
+		raw_spin_lock_irqsave(&mcip_lock, flags);
+		__mcip_cmd(CMD_INTRPT_READ_STATUS, cpu);
+		ipi_was_pending = read_aux_reg(ARC_REG_MCIP_READBACK);
+		if (ipi_was_pending == 0)
+			break; /* break out but keep lock */
+		raw_spin_unlock_irqrestore(&mcip_lock, flags);
+	} while (1);
+
+	__mcip_cmd(CMD_INTRPT_GENERATE_IRQ, cpu);
+	raw_spin_unlock_irqrestore(&mcip_lock, flags);
+
+#ifdef CONFIG_ARC_IPI_DBG
+	if (ipi_was_pending)
+		pr_info("IPI ACK delayed from cpu %d\n", cpu);
+#endif
+}
+
+static void mcip_ipi_clear(int irq)
+{
+	unsigned int cpu, c;
+	unsigned long flags;
+	unsigned int __maybe_unused copy;
+
+	raw_spin_lock_irqsave(&mcip_lock, flags);
+
+	/* Who sent the IPI */
+	__mcip_cmd(CMD_INTRPT_CHECK_SOURCE, 0);
+
+	copy = cpu = read_aux_reg(ARC_REG_MCIP_READBACK);	/* 1,2,4,8... */
+
+	/*
+	 * In rare case, multiple concurrent IPIs sent to same target can
+	 * possibly be coalesced by MCIP into 1 asserted IRQ, so @cpus can be
+	 * "vectored" (multiple bits sets) as opposed to typical single bit
+	 */
+	do {
+		c = __ffs(cpu);			/* 0,1,2,3 */
+		__mcip_cmd(CMD_INTRPT_GENERATE_ACK, c);
+		cpu &= ~(1U << c);
+	} while (cpu);
+
+	raw_spin_unlock_irqrestore(&mcip_lock, flags);
+
+#ifdef CONFIG_ARC_IPI_DBG
+	if (c != __ffs(copy))
+		pr_info("IPIs from %x coalesced to %x\n",
+			copy, raw_smp_processor_id());
+#endif
+}
+
+volatile int wake_flag;
+
+static void mcip_wakeup_cpu(int cpu, unsigned long pc)
+{
+	BUG_ON(cpu == 0);
+	wake_flag = cpu;
+}
+
+void arc_platform_smp_wait_to_boot(int cpu)
+{
+	while (wake_flag != cpu)
+		;
+
+	wake_flag = 0;
+	__asm__ __volatile__("j @first_lines_of_secondary	\n");
+}
+
+struct plat_smp_ops plat_smp_ops = {
+	.info		= smp_cpuinfo_buf,
+	.cpu_kick	= mcip_wakeup_cpu,
+	.ipi_send	= mcip_ipi_send,
+	.ipi_clear	= mcip_ipi_clear,
+};
+
+void mcip_init_early_smp(void)
+{
+#define IS_AVAIL1(var, str)    ((var) ? str : "")
+
+	struct mcip_bcr {
+#ifdef CONFIG_CPU_BIG_ENDIAN
+		unsigned int pad3:8,
+			     idu:1, llm:1, num_cores:6,
+			     iocoh:1,  grtc:1, dbg:1, pad2:1,
+			     msg:1, sem:1, ipi:1, pad:1,
+			     ver:8;
+#else
+		unsigned int ver:8,
+			     pad:1, ipi:1, sem:1, msg:1,
+			     pad2:1, dbg:1, grtc:1, iocoh:1,
+			     num_cores:6, llm:1, idu:1,
+			     pad3:8;
+#endif
+	} mp;
+
+	READ_BCR(ARC_REG_MCIP_BCR, mp);
+
+	sprintf(smp_cpuinfo_buf,
+		"Extn [SMP]\t: ARConnect (v%d): %d cores with %s%s%s%s\n",
+		mp.ver, mp.num_cores,
+		IS_AVAIL1(mp.ipi, "IPI "),
+		IS_AVAIL1(mp.idu, "IDU "),
+		IS_AVAIL1(mp.dbg, "DEBUG "),
+		IS_AVAIL1(mp.grtc, "GRTC"));
+
+	idu_detected = mp.idu;
+
+	if (mp.dbg) {
+		__mcip_cmd_data(CMD_DEBUG_SET_SELECT, 0, 0xf);
+		__mcip_cmd_data(CMD_DEBUG_SET_MASK, 0xf, 0xf);
+	}
+
+	if (IS_ENABLED(CONFIG_ARC_HAS_GRTC) && !mp.grtc)
+		panic("kernel trying to use non-existent GRTC\n");
+}
+
+/***************************************************************************
+ * ARCv2 Interrupt Distribution Unit (IDU)
+ *
+ * Connects external "COMMON" IRQs to core intc, providing:
+ *  -dynamic routing (IRQ affinity)
+ *  -load balancing (Round Robin interrupt distribution)
+ *  -1:N distribution
+ *
+ * It physically resides in the MCIP hw block
+ */
+
+#include <linux/irqchip.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+
+/*
+ * Set the DEST for @cmn_irq to @cpu_mask (1 bit per core)
+ */
+static void idu_set_dest(unsigned int cmn_irq, unsigned int cpu_mask)
+{
+	__mcip_cmd_data(CMD_IDU_SET_DEST, cmn_irq, cpu_mask);
+}
+
+static void idu_set_mode(unsigned int cmn_irq, unsigned int lvl,
+			   unsigned int distr)
+{
+	union {
+		unsigned int word;
+		struct {
+			unsigned int distr:2, pad:2, lvl:1, pad2:27;
+		};
+	} data;
+
+	data.distr = distr;
+	data.lvl = lvl;
+	__mcip_cmd_data(CMD_IDU_SET_MODE, cmn_irq, data.word);
+}
+
+static void idu_irq_mask(struct irq_data *data)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&mcip_lock, flags);
+	__mcip_cmd_data(CMD_IDU_SET_MASK, data->hwirq, 1);
+	raw_spin_unlock_irqrestore(&mcip_lock, flags);
+}
+
+static void idu_irq_unmask(struct irq_data *data)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&mcip_lock, flags);
+	__mcip_cmd_data(CMD_IDU_SET_MASK, data->hwirq, 0);
+	raw_spin_unlock_irqrestore(&mcip_lock, flags);
+}
+
+#ifdef CONFIG_SMP
+static int
+idu_irq_set_affinity(struct irq_data *data, const struct cpumask *cpumask,
+		     bool force)
+{
+	unsigned long flags;
+	cpumask_t online;
+
+	/* errout if no online cpu per @cpumask */
+	if (!cpumask_and(&online, cpumask, cpu_online_mask))
+		return -EINVAL;
+
+	raw_spin_lock_irqsave(&mcip_lock, flags);
+
+	idu_set_dest(data->hwirq, cpumask_bits(&online)[0]);
+	idu_set_mode(data->hwirq, IDU_M_TRIG_LEVEL, IDU_M_DISTRI_RR);
+
+	raw_spin_unlock_irqrestore(&mcip_lock, flags);
+
+	return IRQ_SET_MASK_OK;
+}
+#endif
+
+static struct irq_chip idu_irq_chip = {
+	.name			= "MCIP IDU Intc",
+	.irq_mask		= idu_irq_mask,
+	.irq_unmask		= idu_irq_unmask,
+#ifdef CONFIG_SMP
+	.irq_set_affinity       = idu_irq_set_affinity,
+#endif
+
+};
+
+static int idu_first_irq;
+
+static void idu_cascade_isr(unsigned int core_irq, struct irq_desc *desc)
+{
+	struct irq_domain *domain = irq_desc_get_handler_data(desc);
+	unsigned int idu_irq;
+
+	idu_irq = core_irq - idu_first_irq;
+	generic_handle_irq(irq_find_mapping(domain, idu_irq));
+}
+
+static int idu_irq_map(struct irq_domain *d, unsigned int virq, irq_hw_number_t hwirq)
+{
+	irq_set_chip_and_handler(virq, &idu_irq_chip, handle_level_irq);
+	irq_set_status_flags(virq, IRQ_MOVE_PCNTXT);
+
+	return 0;
+}
+
+static int idu_irq_xlate(struct irq_domain *d, struct device_node *n,
+			 const u32 *intspec, unsigned int intsize,
+			 irq_hw_number_t *out_hwirq, unsigned int *out_type)
+{
+	irq_hw_number_t hwirq = *out_hwirq = intspec[0];
+	int distri = intspec[1];
+	unsigned long flags;
+
+	*out_type = IRQ_TYPE_NONE;
+
+	/* XXX: validate distribution scheme again online cpu mask */
+	if (distri == 0) {
+		/* 0 - Round Robin to all cpus, otherwise 1 bit per core */
+		raw_spin_lock_irqsave(&mcip_lock, flags);
+		idu_set_dest(hwirq, BIT(num_online_cpus()) - 1);
+		idu_set_mode(hwirq, IDU_M_TRIG_LEVEL, IDU_M_DISTRI_RR);
+		raw_spin_unlock_irqrestore(&mcip_lock, flags);
+	} else {
+		/*
+		 * DEST based distribution for Level Triggered intr can only
+		 * have 1 CPU, so generalize it to always contain 1 cpu
+		 */
+		int cpu = ffs(distri);
+
+		if (cpu != fls(distri))
+			pr_warn("IDU irq %lx distri mode set to cpu %x\n",
+				hwirq, cpu);
+
+		raw_spin_lock_irqsave(&mcip_lock, flags);
+		idu_set_dest(hwirq, cpu);
+		idu_set_mode(hwirq, IDU_M_TRIG_LEVEL, IDU_M_DISTRI_DEST);
+		raw_spin_unlock_irqrestore(&mcip_lock, flags);
+	}
+
+	return 0;
+}
+
+static const struct irq_domain_ops idu_irq_ops = {
+	.xlate	= idu_irq_xlate,
+	.map	= idu_irq_map,
+};
+
+/*
+ * [16, 23]: Statically assigned always private-per-core (Timers, WDT, IPI)
+ * [24, 23+C]: If C > 0 then "C" common IRQs
+ * [24+C, N]: Not statically assigned, private-per-core
+ */
+
+
+static int __init
+idu_of_init(struct device_node *intc, struct device_node *parent)
+{
+	struct irq_domain *domain;
+	/* Read IDU BCR to confirm nr_irqs */
+	int nr_irqs = of_irq_count(intc);
+	int i, irq;
+
+	if (!idu_detected)
+		panic("IDU not detected, but DeviceTree using it");
+
+	pr_info("MCIP: IDU referenced from Devicetree %d irqs\n", nr_irqs);
+
+	domain = irq_domain_add_linear(intc, nr_irqs, &idu_irq_ops, NULL);
+
+	/* Parent interrupts (core-intc) are already mapped */
+
+	for (i = 0; i < nr_irqs; i++) {
+		/*
+		 * Return parent uplink IRQs (towards core intc) 24,25,.....
+		 * this step has been done before already
+		 * however we need it to get the parent virq and set IDU handler
+		 * as first level isr
+		 */
+		irq = irq_of_parse_and_map(intc, i);
+		if (!i)
+			idu_first_irq = irq;
+
+		irq_set_chained_handler_and_data(irq, idu_cascade_isr, domain);
+	}
+
+	__mcip_cmd(CMD_IDU_ENABLE, 0);
+
+	return 0;
+}
+IRQCHIP_DECLARE(arcv2_idu_intc, "snps,archs-idu-intc", idu_of_init);