powerpc/xics: Rewrite XICS driver

This is a significant rework of the XICS driver, too significant to
conveniently break it up into a series of smaller patches to be honest.

The driver is moved to a more generic location to allow new platforms
to use it, and is broken up into separate ICP and ICS "backends". For
now we have the native and "hypervisor" ICP backends and one common
RTAS ICS backend.

The driver supports one ICP backend instanciation, and many ICS ones,
in order to accomodate future platforms with multiple possibly different
interrupt "sources" mechanisms.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 461 insertions, 0 deletions

diff --git a/arch/powerpc/sysdev/xics/xics-common.c b/arch/powerpc/sysdev/xics/xics-common.c
new file mode 100644
index 0000000..a2be84d
--- /dev/null
+++ b/arch/powerpc/sysdev/xics/xics-common.c
@@ -0,0 +1,461 @@
+/*
+ * Copyright 2011 IBM Corporation.
+ *
+ *  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/types.h>
+#include <linux/threads.h>
+#include <linux/kernel.h>
+#include <linux/irq.h>
+#include <linux/debugfs.h>
+#include <linux/smp.h>
+#include <linux/interrupt.h>
+#include <linux/seq_file.h>
+#include <linux/init.h>
+#include <linux/cpu.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include <asm/prom.h>
+#include <asm/io.h>
+#include <asm/smp.h>
+#include <asm/machdep.h>
+#include <asm/irq.h>
+#include <asm/errno.h>
+#include <asm/rtas.h>
+#include <asm/xics.h>
+#include <asm/firmware.h>
+
+/* Globals common to all ICP/ICS implementations */
+const struct icp_ops	*icp_ops;
+
+unsigned int xics_default_server		= 0xff;
+unsigned int xics_default_distrib_server	= 0;
+unsigned int xics_interrupt_server_size		= 8;
+
+DEFINE_PER_CPU(struct xics_cppr, xics_cppr);
+
+struct irq_host *xics_host;
+
+static LIST_HEAD(ics_list);
+
+void xics_update_irq_servers(void)
+{
+	int i, j;
+	struct device_node *np;
+	u32 ilen;
+	const u32 *ireg;
+	u32 hcpuid;
+
+	/* Find the server numbers for the boot cpu. */
+	np = of_get_cpu_node(boot_cpuid, NULL);
+	BUG_ON(!np);
+
+	hcpuid = get_hard_smp_processor_id(boot_cpuid);
+	xics_default_server = hcpuid;
+
+	ireg = of_get_property(np, "ibm,ppc-interrupt-gserver#s", &ilen);
+	if (!ireg) {
+		of_node_put(np);
+		return;
+	}
+
+	i = ilen / sizeof(int);
+
+	/* Global interrupt distribution server is specified in the last
+	 * entry of "ibm,ppc-interrupt-gserver#s" property. Get the last
+	 * entry fom this property for current boot cpu id and use it as
+	 * default distribution server
+	 */
+	for (j = 0; j < i; j += 2) {
+		if (ireg[j] == hcpuid) {
+			xics_default_distrib_server = ireg[j+1];
+		}
+	}
+
+	of_node_put(np);
+}
+
+/* GIQ stuff, currently only supported on RTAS setups, will have
+ * to be sorted properly for bare metal
+ */
+void xics_set_cpu_giq(unsigned int gserver, unsigned int join)
+{
+#ifdef CONFIG_PPC_RTAS
+	int index;
+	int status;
+
+	if (!rtas_indicator_present(GLOBAL_INTERRUPT_QUEUE, NULL))
+		return;
+
+	index = (1UL << xics_interrupt_server_size) - 1 - gserver;
+
+	status = rtas_set_indicator_fast(GLOBAL_INTERRUPT_QUEUE, index, join);
+
+	WARN(status < 0, "set-indicator(%d, %d, %u) returned %d\n",
+	     GLOBAL_INTERRUPT_QUEUE, index, join, status);
+#endif
+}
+
+void xics_setup_cpu(void)
+{
+	icp_ops->set_priority(LOWEST_PRIORITY);
+
+	xics_set_cpu_giq(xics_default_distrib_server, 1);
+}
+
+void xics_mask_unknown_vec(unsigned int vec)
+{
+	struct ics *ics;
+
+	pr_err("Interrupt %u (real) is invalid, disabling it.\n", vec);
+
+	list_for_each_entry(ics, &ics_list, link)
+		ics->mask_unknown(ics, vec);
+}
+
+
+#ifdef CONFIG_SMP
+
+DEFINE_PER_CPU_SHARED_ALIGNED(unsigned long, xics_ipi_message);
+
+irqreturn_t xics_ipi_dispatch(int cpu)
+{
+	unsigned long *tgt = &per_cpu(xics_ipi_message, cpu);
+
+	mb();	/* order mmio clearing qirr */
+	while (*tgt) {
+		if (test_and_clear_bit(PPC_MSG_CALL_FUNCTION, tgt)) {
+			smp_message_recv(PPC_MSG_CALL_FUNCTION);
+		}
+		if (test_and_clear_bit(PPC_MSG_RESCHEDULE, tgt)) {
+			smp_message_recv(PPC_MSG_RESCHEDULE);
+		}
+		if (test_and_clear_bit(PPC_MSG_CALL_FUNC_SINGLE, tgt)) {
+			smp_message_recv(PPC_MSG_CALL_FUNC_SINGLE);
+		}
+#if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
+		if (test_and_clear_bit(PPC_MSG_DEBUGGER_BREAK, tgt)) {
+			smp_message_recv(PPC_MSG_DEBUGGER_BREAK);
+		}
+#endif
+	}
+	return IRQ_HANDLED;
+}
+
+static void xics_request_ipi(void)
+{
+	unsigned int ipi;
+
+	ipi = irq_create_mapping(xics_host, XICS_IPI);
+	BUG_ON(ipi == NO_IRQ);
+
+	/*
+	 * IPIs are marked IRQF_DISABLED as they must run with irqs
+	 * disabled
+	 */
+	irq_set_handler(ipi, handle_percpu_irq);
+	BUG_ON(request_irq(ipi, icp_ops->ipi_action,
+			   IRQF_DISABLED|IRQF_PERCPU, "IPI", NULL));
+}
+
+int __init xics_smp_probe(void)
+{
+	/* Setup message_pass callback  based on which ICP is used */
+	smp_ops->message_pass = icp_ops->message_pass;
+
+	/* Register all the IPIs */
+	xics_request_ipi();
+
+	return cpumask_weight(cpu_possible_mask);
+}
+
+#endif /* CONFIG_SMP */
+
+void xics_teardown_cpu(void)
+{
+	struct xics_cppr *os_cppr = &__get_cpu_var(xics_cppr);
+
+	/*
+	 * we have to reset the cppr index to 0 because we're
+	 * not going to return from the IPI
+	 */
+	os_cppr->index = 0;
+	icp_ops->set_priority(0);
+	icp_ops->teardown_cpu();
+}
+
+void xics_kexec_teardown_cpu(int secondary)
+{
+	xics_teardown_cpu();
+
+	icp_ops->flush_ipi();
+
+	/*
+	 * Some machines need to have at least one cpu in the GIQ,
+	 * so leave the master cpu in the group.
+	 */
+	if (secondary)
+		xics_set_cpu_giq(xics_default_distrib_server, 0);
+}
+
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+/* Interrupts are disabled. */
+void xics_migrate_irqs_away(void)
+{
+	int cpu = smp_processor_id(), hw_cpu = hard_smp_processor_id();
+	unsigned int irq, virq;
+
+	/* If we used to be the default server, move to the new "boot_cpuid" */
+	if (hw_cpu == xics_default_server)
+		xics_update_irq_servers();
+
+	/* Reject any interrupt that was queued to us... */
+	icp_ops->set_priority(0);
+
+	/* Remove ourselves from the global interrupt queue */
+	xics_set_cpu_giq(xics_default_distrib_server, 0);
+
+	/* Allow IPIs again... */
+	icp_ops->set_priority(DEFAULT_PRIORITY);
+
+	for_each_irq(virq) {
+		struct irq_desc *desc;
+		struct irq_chip *chip;
+		long server;
+		unsigned long flags;
+		struct ics *ics;
+
+		/* We can't set affinity on ISA interrupts */
+		if (virq < NUM_ISA_INTERRUPTS)
+			continue;
+		if (irq_map[virq].host != xics_host)
+			continue;
+		irq = (unsigned int)irq_map[virq].hwirq;
+		/* We need to get IPIs still. */
+		if (irq == XICS_IPI || irq == XICS_IRQ_SPURIOUS)
+			continue;
+		desc = irq_to_desc(virq);
+		/* We only need to migrate enabled IRQS */
+		if (!desc || !desc->action)
+			continue;
+		chip = irq_desc_get_chip(desc);
+		if (!chip || !chip->irq_set_affinity)
+			continue;
+
+		raw_spin_lock_irqsave(&desc->lock, flags);
+
+		/* Locate interrupt server */
+		server = -1;
+		ics = irq_get_chip_data(virq);
+		if (ics)
+			server = ics->get_server(ics, irq);
+		if (server < 0) {
+			printk(KERN_ERR "%s: Can't find server for irq %d\n",
+			       __func__, irq);
+			goto unlock;
+		}
+
+		/* We only support delivery to all cpus or to one cpu.
+		 * The irq has to be migrated only in the single cpu
+		 * case.
+		 */
+		if (server != hw_cpu)
+			goto unlock;
+
+		/* This is expected during cpu offline. */
+		if (cpu_online(cpu))
+			pr_warning("IRQ %u affinity broken off cpu %u\n",
+			       virq, cpu);
+
+		/* Reset affinity to all cpus */
+		raw_spin_unlock_irqrestore(&desc->lock, flags);
+		irq_set_affinity(virq, cpu_all_mask);
+		continue;
+unlock:
+		raw_spin_unlock_irqrestore(&desc->lock, flags);
+	}
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
+#ifdef CONFIG_SMP
+/*
+ * For the moment we only implement delivery to all cpus or one cpu.
+ *
+ * If the requested affinity is cpu_all_mask, we set global affinity.
+ * If not we set it to the first cpu in the mask, even if multiple cpus
+ * are set. This is so things like irqbalance (which set core and package
+ * wide affinities) do the right thing.
+ */
+int xics_get_irq_server(unsigned int virq, const struct cpumask *cpumask,
+			unsigned int strict_check)
+{
+
+	if (!distribute_irqs)
+		return xics_default_server;
+
+	if (!cpumask_subset(cpu_possible_mask, cpumask)) {
+		int server = cpumask_first_and(cpu_online_mask, cpumask);
+
+		if (server < nr_cpu_ids)
+			return get_hard_smp_processor_id(server);
+
+		if (strict_check)
+			return -1;
+	}
+
+	/*
+	 * Workaround issue with some versions of JS20 firmware that
+	 * deliver interrupts to cpus which haven't been started. This
+	 * happens when using the maxcpus= boot option.
+	 */
+	if (cpumask_equal(cpu_online_mask, cpu_present_mask))
+		return xics_default_distrib_server;
+
+	return xics_default_server;
+}
+#endif /* CONFIG_SMP */
+
+static int xics_host_match(struct irq_host *h, struct device_node *node)
+{
+	/* IBM machines have interrupt parents of various funky types for things
+	 * like vdevices, events, etc... The trick we use here is to match
+	 * everything here except the legacy 8259 which is compatible "chrp,iic"
+	 */
+	return !of_device_is_compatible(node, "chrp,iic");
+}
+
+/* Dummies */
+static void xics_ipi_unmask(struct irq_data *d) { }
+static void xics_ipi_mask(struct irq_data *d) { }
+
+static struct irq_chip xics_ipi_chip = {
+	.name = "XICS",
+	.irq_eoi = NULL, /* Patched at init time */
+	.irq_mask = xics_ipi_mask,
+	.irq_unmask = xics_ipi_unmask,
+};
+
+static int xics_host_map(struct irq_host *h, unsigned int virq,
+			 irq_hw_number_t hw)
+{
+	struct ics *ics;
+
+	pr_devel("xics: map virq %d, hwirq 0x%lx\n", virq, hw);
+
+	/* Insert the interrupt mapping into the radix tree for fast lookup */
+	irq_radix_revmap_insert(xics_host, virq, hw);
+
+	/* They aren't all level sensitive but we just don't really know */
+	irq_set_status_flags(virq, IRQ_LEVEL);
+
+	/* Don't call into ICS for IPIs */
+	if (hw == XICS_IPI) {
+		irq_set_chip_and_handler(virq, &xics_ipi_chip,
+					 handle_fasteoi_irq);
+		return 0;
+	}
+
+	/* Let the ICS setup the chip data */
+	list_for_each_entry(ics, &ics_list, link)
+		if (ics->map(ics, virq) == 0)
+			break;
+	return 0;
+}
+
+static int xics_host_xlate(struct irq_host *h, struct device_node *ct,
+			   const u32 *intspec, unsigned int intsize,
+			   irq_hw_number_t *out_hwirq, unsigned int *out_flags)
+
+{
+	/* Current xics implementation translates everything
+	 * to level. It is not technically right for MSIs but this
+	 * is irrelevant at this point. We might get smarter in the future
+	 */
+	*out_hwirq = intspec[0];
+	*out_flags = IRQ_TYPE_LEVEL_LOW;
+
+	return 0;
+}
+
+static struct irq_host_ops xics_host_ops = {
+	.match = xics_host_match,
+	.map = xics_host_map,
+	.xlate = xics_host_xlate,
+};
+
+static void __init xics_init_host(void)
+{
+	xics_host = irq_alloc_host(NULL, IRQ_HOST_MAP_TREE, 0, &xics_host_ops,
+				   XICS_IRQ_SPURIOUS);
+	BUG_ON(xics_host == NULL);
+	irq_set_default_host(xics_host);
+}
+
+void __init xics_register_ics(struct ics *ics)
+{
+	list_add(&ics->link, &ics_list);
+}
+
+static void __init xics_get_server_size(void)
+{
+	struct device_node *np;
+	const u32 *isize;
+
+	/* We fetch the interrupt server size from the first ICS node
+	 * we find if any
+	 */
+	np = of_find_compatible_node(NULL, NULL, "ibm,ppc-xics");
+	if (!np)
+		return;
+	isize = of_get_property(np, "ibm,interrupt-server#-size", NULL);
+	if (!isize)
+		return;
+	xics_interrupt_server_size = *isize;
+	of_node_put(np);
+}
+
+void __init xics_init(void)
+{
+	int rc = -1;
+
+	/* Fist locate ICP */
+#ifdef CONFIG_PPC_ICP_HV
+	if (firmware_has_feature(FW_FEATURE_LPAR))
+		rc = icp_hv_init();
+#endif
+#ifdef CONFIG_PPC_ICP_NATIVE
+	if (rc < 0)
+		rc = icp_native_init();
+#endif
+	if (rc < 0) {
+		pr_warning("XICS: Cannot find a Presentation Controller !\n");
+		return;
+	}
+
+	/* Copy get_irq callback over to ppc_md */
+	ppc_md.get_irq = icp_ops->get_irq;
+
+	/* Patch up IPI chip EOI */
+	xics_ipi_chip.irq_eoi = icp_ops->eoi;
+
+	/* Now locate ICS */
+#ifdef CONFIG_PPC_ICS_RTAS
+	rc = ics_rtas_init();
+#endif
+	if (rc < 0)
+		pr_warning("XICS: Cannot find a Source Controller !\n");
+
+	/* Initialize common bits */
+	xics_get_server_size();
+	xics_update_irq_servers();
+	xics_init_host();
+	xics_setup_cpu();
+}