1 files changed, 393 insertions, 0 deletions
diff --git a/arch/x86/platform/uv/uv_time.c b/arch/x86/platform/uv/uv_time.c
new file mode 100644
index 000000000..54663f3e0
--- /dev/null
+++ b/arch/x86/platform/uv/uv_time.c
@@ -0,0 +1,393 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * SGI RTC clock/timer routines.
+ *
+ *  (C) Copyright 2020 Hewlett Packard Enterprise Development LP
+ *  Copyright (c) 2009-2013 Silicon Graphics, Inc.  All Rights Reserved.
+ *  Copyright (c) Dimitri Sivanich
+ */
+#include <linux/clockchips.h>
+#include <linux/slab.h>
+
+#include <asm/uv/uv_mmrs.h>
+#include <asm/uv/uv_hub.h>
+#include <asm/uv/bios.h>
+#include <asm/uv/uv.h>
+#include <asm/apic.h>
+#include <asm/cpu.h>
+
+#define RTC_NAME		"sgi_rtc"
+
+static u64 uv_read_rtc(struct clocksource *cs);
+static int uv_rtc_next_event(unsigned long, struct clock_event_device *);
+static int uv_rtc_shutdown(struct clock_event_device *evt);
+
+static struct clocksource clocksource_uv = {
+	.name		= RTC_NAME,
+	.rating		= 299,
+	.read		= uv_read_rtc,
+	.mask		= (u64)UVH_RTC_REAL_TIME_CLOCK_MASK,
+	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static struct clock_event_device clock_event_device_uv = {
+	.name			= RTC_NAME,
+	.features		= CLOCK_EVT_FEAT_ONESHOT,
+	.shift			= 20,
+	.rating			= 400,
+	.irq			= -1,
+	.set_next_event		= uv_rtc_next_event,
+	.set_state_shutdown	= uv_rtc_shutdown,
+	.event_handler		= NULL,
+};
+
+static DEFINE_PER_CPU(struct clock_event_device, cpu_ced);
+
+/* There is one of these allocated per node */
+struct uv_rtc_timer_head {
+	spinlock_t	lock;
+	/* next cpu waiting for timer, local node relative: */
+	int		next_cpu;
+	/* number of cpus on this node: */
+	int		ncpus;
+	struct {
+		int	lcpu;		/* systemwide logical cpu number */
+		u64	expires;	/* next timer expiration for this cpu */
+	} cpu[];
+};
+
+/*
+ * Access to uv_rtc_timer_head via blade id.
+ */
+static struct uv_rtc_timer_head		**blade_info __read_mostly;
+
+static int				uv_rtc_evt_enable;
+
+/*
+ * Hardware interface routines
+ */
+
+/* Send IPIs to another node */
+static void uv_rtc_send_IPI(int cpu)
+{
+	unsigned long apicid, val;
+	int pnode;
+
+	apicid = cpu_physical_id(cpu);
+	pnode = uv_apicid_to_pnode(apicid);
+	val = (1UL << UVH_IPI_INT_SEND_SHFT) |
+	      (apicid << UVH_IPI_INT_APIC_ID_SHFT) |
+	      (X86_PLATFORM_IPI_VECTOR << UVH_IPI_INT_VECTOR_SHFT);
+
+	uv_write_global_mmr64(pnode, UVH_IPI_INT, val);
+}
+
+/* Check for an RTC interrupt pending */
+static int uv_intr_pending(int pnode)
+{
+	return uv_read_global_mmr64(pnode, UVH_EVENT_OCCURRED2) &
+		UVH_EVENT_OCCURRED2_RTC_1_MASK;
+}
+
+/* Setup interrupt and return non-zero if early expiration occurred. */
+static int uv_setup_intr(int cpu, u64 expires)
+{
+	u64 val;
+	unsigned long apicid = cpu_physical_id(cpu);
+	int pnode = uv_cpu_to_pnode(cpu);
+
+	uv_write_global_mmr64(pnode, UVH_RTC1_INT_CONFIG,
+		UVH_RTC1_INT_CONFIG_M_MASK);
+	uv_write_global_mmr64(pnode, UVH_INT_CMPB, -1L);
+
+	uv_write_global_mmr64(pnode, UVH_EVENT_OCCURRED2_ALIAS,
+			      UVH_EVENT_OCCURRED2_RTC_1_MASK);
+
+	val = (X86_PLATFORM_IPI_VECTOR << UVH_RTC1_INT_CONFIG_VECTOR_SHFT) |
+		((u64)apicid << UVH_RTC1_INT_CONFIG_APIC_ID_SHFT);
+
+	/* Set configuration */
+	uv_write_global_mmr64(pnode, UVH_RTC1_INT_CONFIG, val);
+	/* Initialize comparator value */
+	uv_write_global_mmr64(pnode, UVH_INT_CMPB, expires);
+
+	if (uv_read_rtc(NULL) <= expires)
+		return 0;
+
+	return !uv_intr_pending(pnode);
+}
+
+/*
+ * Per-cpu timer tracking routines
+ */
+
+static __init void uv_rtc_deallocate_timers(void)
+{
+	int bid;
+
+	for_each_possible_blade(bid) {
+		kfree(blade_info[bid]);
+	}
+	kfree(blade_info);
+}
+
+/* Allocate per-node list of cpu timer expiration times. */
+static __init int uv_rtc_allocate_timers(void)
+{
+	int cpu;
+
+	blade_info = kcalloc(uv_possible_blades, sizeof(void *), GFP_KERNEL);
+	if (!blade_info)
+		return -ENOMEM;
+
+	for_each_present_cpu(cpu) {
+		int nid = cpu_to_node(cpu);
+		int bid = uv_cpu_to_blade_id(cpu);
+		int bcpu = uv_cpu_blade_processor_id(cpu);
+		struct uv_rtc_timer_head *head = blade_info[bid];
+
+		if (!head) {
+			head = kmalloc_node(struct_size(head, cpu,
+				uv_blade_nr_possible_cpus(bid)),
+				GFP_KERNEL, nid);
+			if (!head) {
+				uv_rtc_deallocate_timers();
+				return -ENOMEM;
+			}
+			spin_lock_init(&head->lock);
+			head->ncpus = uv_blade_nr_possible_cpus(bid);
+			head->next_cpu = -1;
+			blade_info[bid] = head;
+		}
+
+		head->cpu[bcpu].lcpu = cpu;
+		head->cpu[bcpu].expires = ULLONG_MAX;
+	}
+
+	return 0;
+}
+
+/* Find and set the next expiring timer.  */
+static void uv_rtc_find_next_timer(struct uv_rtc_timer_head *head, int pnode)
+{
+	u64 lowest = ULLONG_MAX;
+	int c, bcpu = -1;
+
+	head->next_cpu = -1;
+	for (c = 0; c < head->ncpus; c++) {
+		u64 exp = head->cpu[c].expires;
+		if (exp < lowest) {
+			bcpu = c;
+			lowest = exp;
+		}
+	}
+	if (bcpu >= 0) {
+		head->next_cpu = bcpu;
+		c = head->cpu[bcpu].lcpu;
+		if (uv_setup_intr(c, lowest))
+			/* If we didn't set it up in time, trigger */
+			uv_rtc_send_IPI(c);
+	} else {
+		uv_write_global_mmr64(pnode, UVH_RTC1_INT_CONFIG,
+			UVH_RTC1_INT_CONFIG_M_MASK);
+	}
+}
+
+/*
+ * Set expiration time for current cpu.
+ *
+ * Returns 1 if we missed the expiration time.
+ */
+static int uv_rtc_set_timer(int cpu, u64 expires)
+{
+	int pnode = uv_cpu_to_pnode(cpu);
+	int bid = uv_cpu_to_blade_id(cpu);
+	struct uv_rtc_timer_head *head = blade_info[bid];
+	int bcpu = uv_cpu_blade_processor_id(cpu);
+	u64 *t = &head->cpu[bcpu].expires;
+	unsigned long flags;
+	int next_cpu;
+
+	spin_lock_irqsave(&head->lock, flags);
+
+	next_cpu = head->next_cpu;
+	*t = expires;
+
+	/* Will this one be next to go off? */
+	if (next_cpu < 0 || bcpu == next_cpu ||
+			expires < head->cpu[next_cpu].expires) {
+		head->next_cpu = bcpu;
+		if (uv_setup_intr(cpu, expires)) {
+			*t = ULLONG_MAX;
+			uv_rtc_find_next_timer(head, pnode);
+			spin_unlock_irqrestore(&head->lock, flags);
+			return -ETIME;
+		}
+	}
+
+	spin_unlock_irqrestore(&head->lock, flags);
+	return 0;
+}
+
+/*
+ * Unset expiration time for current cpu.
+ *
+ * Returns 1 if this timer was pending.
+ */
+static int uv_rtc_unset_timer(int cpu, int force)
+{
+	int pnode = uv_cpu_to_pnode(cpu);
+	int bid = uv_cpu_to_blade_id(cpu);
+	struct uv_rtc_timer_head *head = blade_info[bid];
+	int bcpu = uv_cpu_blade_processor_id(cpu);
+	u64 *t = &head->cpu[bcpu].expires;
+	unsigned long flags;
+	int rc = 0;
+
+	spin_lock_irqsave(&head->lock, flags);
+
+	if ((head->next_cpu == bcpu && uv_read_rtc(NULL) >= *t) || force)
+		rc = 1;
+
+	if (rc) {
+		*t = ULLONG_MAX;
+		/* Was the hardware setup for this timer? */
+		if (head->next_cpu == bcpu)
+			uv_rtc_find_next_timer(head, pnode);
+	}
+
+	spin_unlock_irqrestore(&head->lock, flags);
+
+	return rc;
+}
+
+
+/*
+ * Kernel interface routines.
+ */
+
+/*
+ * Read the RTC.
+ *
+ * Starting with HUB rev 2.0, the UV RTC register is replicated across all
+ * cachelines of it's own page.  This allows faster simultaneous reads
+ * from a given socket.
+ */
+static u64 uv_read_rtc(struct clocksource *cs)
+{
+	unsigned long offset;
+
+	if (uv_get_min_hub_revision_id() == 1)
+		offset = 0;
+	else
+		offset = (uv_blade_processor_id() * L1_CACHE_BYTES) % PAGE_SIZE;
+
+	return (u64)uv_read_local_mmr(UVH_RTC | offset);
+}
+
+/*
+ * Program the next event, relative to now
+ */
+static int uv_rtc_next_event(unsigned long delta,
+			     struct clock_event_device *ced)
+{
+	int ced_cpu = cpumask_first(ced->cpumask);
+
+	return uv_rtc_set_timer(ced_cpu, delta + uv_read_rtc(NULL));
+}
+
+/*
+ * Shutdown the RTC timer
+ */
+static int uv_rtc_shutdown(struct clock_event_device *evt)
+{
+	int ced_cpu = cpumask_first(evt->cpumask);
+
+	uv_rtc_unset_timer(ced_cpu, 1);
+	return 0;
+}
+
+static void uv_rtc_interrupt(void)
+{
+	int cpu = smp_processor_id();
+	struct clock_event_device *ced = &per_cpu(cpu_ced, cpu);
+
+	if (!ced || !ced->event_handler)
+		return;
+
+	if (uv_rtc_unset_timer(cpu, 0) != 1)
+		return;
+
+	ced->event_handler(ced);
+}
+
+static int __init uv_enable_evt_rtc(char *str)
+{
+	uv_rtc_evt_enable = 1;
+
+	return 1;
+}
+__setup("uvrtcevt", uv_enable_evt_rtc);
+
+static __init void uv_rtc_register_clockevents(struct work_struct *dummy)
+{
+	struct clock_event_device *ced = this_cpu_ptr(&cpu_ced);
+
+	*ced = clock_event_device_uv;
+	ced->cpumask = cpumask_of(smp_processor_id());
+	clockevents_register_device(ced);
+}
+
+static __init int uv_rtc_setup_clock(void)
+{
+	int rc;
+
+	if (!is_uv_system())
+		return -ENODEV;
+
+	rc = clocksource_register_hz(&clocksource_uv, sn_rtc_cycles_per_second);
+	if (rc)
+		printk(KERN_INFO "UV RTC clocksource failed rc %d\n", rc);
+	else
+		printk(KERN_INFO "UV RTC clocksource registered freq %lu MHz\n",
+			sn_rtc_cycles_per_second/(unsigned long)1E6);
+
+	if (rc || !uv_rtc_evt_enable || x86_platform_ipi_callback)
+		return rc;
+
+	/* Setup and register clockevents */
+	rc = uv_rtc_allocate_timers();
+	if (rc)
+		goto error;
+
+	x86_platform_ipi_callback = uv_rtc_interrupt;
+
+	clock_event_device_uv.mult = div_sc(sn_rtc_cycles_per_second,
+				NSEC_PER_SEC, clock_event_device_uv.shift);
+
+	clock_event_device_uv.min_delta_ns = NSEC_PER_SEC /
+						sn_rtc_cycles_per_second;
+	clock_event_device_uv.min_delta_ticks = 1;
+
+	clock_event_device_uv.max_delta_ns = clocksource_uv.mask *
+				(NSEC_PER_SEC / sn_rtc_cycles_per_second);
+	clock_event_device_uv.max_delta_ticks = clocksource_uv.mask;
+
+	rc = schedule_on_each_cpu(uv_rtc_register_clockevents);
+	if (rc) {
+		x86_platform_ipi_callback = NULL;
+		uv_rtc_deallocate_timers();
+		goto error;
+	}
+
+	printk(KERN_INFO "UV RTC clockevents registered\n");
+
+	return 0;
+
+error:
+	clocksource_unregister(&clocksource_uv);
+	printk(KERN_INFO "UV RTC clockevents failed rc %d\n", rc);
+
+	return rc;
+}
+arch_initcall(uv_rtc_setup_clock);