[PATCH 3/3 v7] SGI RTC: add UV RTC clocksource/clockevents

Dimitri Sivanich
2009-03-04T18:59:31Z

This patch provides a high resolution clock/timer source using the
SGI UV system-wide synchronized RTC clock/timer hardware.

Signed-off-by: Dimitri Sivanich <sivanich@sgi.com>

---

Made suggested simplifications.

arch/x86/kernel/Makefile | 2
arch/x86/kernel/uv_time.c | 386 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 387 insertions(+), 1 deletion(-)

Index: linux/arch/x86/kernel/uv_time.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux/arch/x86/kernel/uv_time.c 2009-03-04 11:20:38.000000000 -0600
@@ -0,0 +1,386 @@
+/*
+ * SGI RTC clock/timer routines.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Copyright (c) 2009 Silicon Graphics, Inc. All Rights Reserved.
+ * Copyright (c) Dimitri Sivanich
+ */
+#include <linux/clockchips.h>
+#include <asm/uv/uv.h>
+#include <asm/uv/uv_mmrs.h>
+#include <asm/uv/uv_hub.h>
+#include <asm/uv/bios.h>
+
+#define RTC_NAME "sgi_rtc"
+
+static cycle_t uv_read_rtc(void);
+static int uv_rtc_next_event(unsigned long, struct clock_event_device *);
+static void uv_rtc_timer_setup(enum clock_event_mode,
+ struct clock_event_device *);
+
+static struct clocksource clocksource_uv = {
+ .name = RTC_NAME,
+ .rating = 400,
+ .read = uv_read_rtc,
+ .mask = (cycle_t)UVH_RTC_REAL_TIME_CLOCK_MASK,
+ .shift = 10,
+ .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_mode = uv_rtc_timer_setup,
+ .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;
+ int next_cpu; /* next cpu waiting for timer, local node relative */
+ int ncpus; /* number of cpus on this node */
+ struct {
+ int lcpu; /* systemwide logical cpu number */
+ u64 expires; /* next timer expiration for this cpu */
+ } cpu[1];
+};
+
+/*
+ * Access to uv_rtc_timer_head via blade id.
+ */
+static struct uv_rtc_timer_head **blade_info __read_mostly;
+
+static int uv_rtc_enable;
+
+/*
+ * Hardware interface routines
+ */
+
+/* Send IPIs to another node */
+static void uv_rtc_send_IPI(int cpu)
+{
+ unsigned long apicid, val;
+ int pnode;
+
+ apicid = per_cpu(x86_cpu_to_apicid, cpu);
+ pnode = uv_apicid_to_pnode(apicid);
+ val = (1UL << UVH_IPI_INT_SEND_SHFT) |
+ (apicid << UVH_IPI_INT_APIC_ID_SHFT) |
+ (GENERIC_INTERRUPT_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_OCCURRED0) &
+ UVH_EVENT_OCCURRED0_RTC1_MASK;
+}
+
+/* Setup interrupt and return non-zero if early expiration occurred. */
+static int uv_setup_intr(int cpu, u64 expires)
+{
+ u64 val;
+ 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_OCCURRED0_ALIAS,
+ UVH_EVENT_OCCURRED0_RTC1_MASK);
+
+ val = (GENERIC_INTERRUPT_VECTOR << UVH_RTC1_INT_CONFIG_VECTOR_SHFT) |
+ ((u64)cpu_physical_id(cpu) << 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);
+
+ return (expires < uv_read_rtc() && !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 = kmalloc(uv_possible_blades * sizeof(void *), GFP_KERNEL);
+ if (!blade_info)
+ return -ENOMEM;
+ memset(blade_info, 0, uv_possible_blades * sizeof(void *));
+
+ for_each_present_cpu(cpu) {
+ int nid = cpu_to_node(cpu);
+ int bid = uv_cpu_to_blade_id(cpu);
+ int bcpu = uv_cpu_hub_info(cpu)->blade_processor_id;
+ struct uv_rtc_timer_head *head = blade_info[bid];
+
+ if (!head) {
+ head = kmalloc_node(sizeof(struct uv_rtc_timer_head) +
+ (uv_blade_nr_possible_cpus(bid) *
+ 2 * sizeof(u64)),
+ 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_hub_info(cpu)->blade_processor_id;
+ 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 1;
+ }
+ }
+
+ 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 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_hub_info(cpu)->blade_processor_id;
+ 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() >= *t)
+ rc = 1;
+
+ *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.
+ */
+static cycle_t uv_read_rtc(void)
+{
+ return (cycle_t)uv_read_local_mmr(UVH_RTC);
+}
+
+/*
+ * 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());
+}
+
+/*
+ * Setup the RTC timer in oneshot mode
+ */
+static void uv_rtc_timer_setup(enum clock_event_mode mode,
+ struct clock_event_device *evt)
+{
+ int ced_cpu = cpumask_first(evt->cpumask);
+
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ case CLOCK_EVT_MODE_ONESHOT:
+ case CLOCK_EVT_MODE_RESUME:
+ /* Nothing to do here yet */
+ break;
+ case CLOCK_EVT_MODE_UNUSED:
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ uv_rtc_unset_timer(ced_cpu);
+ break;
+ }
+}
+
+static void uv_rtc_interrupt(void)
+{
+ struct clock_event_device *ced = &__get_cpu_var(cpu_ced);
+ int cpu = smp_processor_id();
+
+ if (!ced || !ced->event_handler)
+ return;
+
+ if (uv_rtc_unset_timer(cpu) != 1)
+ return;
+
+ ced->event_handler(ced);
+}
+
+static int __init uv_enable_rtc(char *str)
+{
+ uv_rtc_enable = 1;
+
+ return 1;
+}
+__setup("uvrtc", uv_enable_rtc);
+
+static __init void uv_rtc_register_clockevents(struct work_struct *dummy)
+{
+ struct clock_event_device *ced = &__get_cpu_var(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 (!uv_rtc_enable || !is_uv_system() || generic_interrupt_extension)
+ return -ENODEV;
+
+ generic_interrupt_extension = uv_rtc_interrupt;
+
+ clocksource_uv.mult = clocksource_hz2mult(sn_rtc_cycles_per_second,
+ clocksource_uv.shift);
+
+ rc = clocksource_register(&clocksource_uv);
+ if (rc) {
+ generic_interrupt_extension = NULL;
+ return rc;
+ }
+
+ /* Setup and register clockevents */
+ rc = uv_rtc_allocate_timers();
+ if (rc) {
+ clocksource_unregister(&clocksource_uv);
+ generic_interrupt_extension = NULL;
+ return rc;
+ }
+
+ 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.max_delta_ns = clocksource_uv.mask *
+ (NSEC_PER_SEC / sn_rtc_cycles_per_second);
+
+ rc = schedule_on_each_cpu(uv_rtc_register_clockevents);
+ if (rc) {
+ clocksource_unregister(&clocksource_uv);
+ generic_interrupt_extension = NULL;
+ uv_rtc_deallocate_timers();
+ }
+
+ return rc;
+}
+arch_initcall(uv_rtc_setup_clock);
Index: linux/arch/x86/kernel/Makefile
===================================================================
--- linux.orig/arch/x86/kernel/Makefile 2009-03-04 11:07:46.000000000 -0600
+++ linux/arch/x86/kernel/Makefile 2009-03-04 11:07:56.000000000 -0600
@@ -111,7 +111,7 @@ obj-$(CONFIG_SWIOTLB) += pci-swiotlb.o
###
# 64 bit specific files
ifeq ($(CONFIG_X86_64),y)
- obj-$(CONFIG_X86_UV) += tlb_uv.o bios_uv.o uv_irq.o uv_sysfs.o
+ obj-$(CONFIG_X86_UV) += tlb_uv.o bios_uv.o uv_irq.o uv_sysfs.o uv_time.o
obj-$(CONFIG_X86_PM_TIMER) += pmtimer_64.o
obj-$(CONFIG_AUDIT) += audit_64.o