Drivers: hv: vmbus: Implement a clockevent device
Implement a clockevent device based on the timer support available on
Hyper-V.
In this version of the patch I have addressed Jason's review comments.
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 3e4235c..50e51a5 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -28,7 +28,9 @@
#include <linux/hyperv.h>
#include <linux/version.h>
#include <linux/interrupt.h>
+#include <linux/clockchips.h>
#include <asm/hyperv.h>
+#include <asm/mshyperv.h>
#include "hyperv_vmbus.h"
/* The one and only */
@@ -37,6 +39,10 @@
.hypercall_page = NULL,
};
+#define HV_TIMER_FREQUENCY (10 * 1000 * 1000) /* 100ns period */
+#define HV_MAX_MAX_DELTA_TICKS 0xffffffff
+#define HV_MIN_DELTA_TICKS 1
+
/*
* query_hypervisor_info - Get version info of the windows hypervisor
*/
@@ -144,6 +150,8 @@
sizeof(int) * NR_CPUS);
memset(hv_context.event_dpc, 0,
sizeof(void *) * NR_CPUS);
+ memset(hv_context.clk_evt, 0,
+ sizeof(void *) * NR_CPUS);
max_leaf = query_hypervisor_info();
@@ -258,10 +266,63 @@
return status;
}
+static int hv_ce_set_next_event(unsigned long delta,
+ struct clock_event_device *evt)
+{
+ cycle_t current_tick;
+
+ WARN_ON(evt->mode != CLOCK_EVT_MODE_ONESHOT);
+
+ rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
+ current_tick += delta;
+ wrmsrl(HV_X64_MSR_STIMER0_COUNT, current_tick);
+ return 0;
+}
+
+static void hv_ce_setmode(enum clock_event_mode mode,
+ struct clock_event_device *evt)
+{
+ union hv_timer_config timer_cfg;
+
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ /* unsupported */
+ break;
+
+ case CLOCK_EVT_MODE_ONESHOT:
+ timer_cfg.enable = 1;
+ timer_cfg.auto_enable = 1;
+ timer_cfg.sintx = VMBUS_MESSAGE_SINT;
+ wrmsrl(HV_X64_MSR_STIMER0_CONFIG, timer_cfg.as_uint64);
+ break;
+
+ case CLOCK_EVT_MODE_UNUSED:
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ wrmsrl(HV_X64_MSR_STIMER0_COUNT, 0);
+ wrmsrl(HV_X64_MSR_STIMER0_CONFIG, 0);
+ break;
+ case CLOCK_EVT_MODE_RESUME:
+ break;
+ }
+}
+
+static void hv_init_clockevent_device(struct clock_event_device *dev, int cpu)
+{
+ dev->name = "Hyper-V clockevent";
+ dev->features = CLOCK_EVT_FEAT_ONESHOT;
+ dev->cpumask = cpumask_of(cpu);
+ dev->rating = 1000;
+ dev->owner = THIS_MODULE;
+
+ dev->set_mode = hv_ce_setmode;
+ dev->set_next_event = hv_ce_set_next_event;
+}
+
int hv_synic_alloc(void)
{
size_t size = sizeof(struct tasklet_struct);
+ size_t ced_size = sizeof(struct clock_event_device);
int cpu;
for_each_online_cpu(cpu) {
@@ -272,6 +333,13 @@
}
tasklet_init(hv_context.event_dpc[cpu], vmbus_on_event, cpu);
+ hv_context.clk_evt[cpu] = kzalloc(ced_size, GFP_ATOMIC);
+ if (hv_context.clk_evt[cpu] == NULL) {
+ pr_err("Unable to allocate clock event device\n");
+ goto err;
+ }
+ hv_init_clockevent_device(hv_context.clk_evt[cpu], cpu);
+
hv_context.synic_message_page[cpu] =
(void *)get_zeroed_page(GFP_ATOMIC);
@@ -305,6 +373,7 @@
static void hv_synic_free_cpu(int cpu)
{
kfree(hv_context.event_dpc[cpu]);
+ kfree(hv_context.clk_evt[cpu]);
if (hv_context.synic_event_page[cpu])
free_page((unsigned long)hv_context.synic_event_page[cpu]);
if (hv_context.synic_message_page[cpu])
@@ -388,6 +457,15 @@
hv_context.vp_index[cpu] = (u32)vp_index;
INIT_LIST_HEAD(&hv_context.percpu_list[cpu]);
+
+ /*
+ * Register the per-cpu clockevent source.
+ */
+ if (ms_hyperv.features & HV_X64_MSR_SYNTIMER_AVAILABLE)
+ clockevents_config_and_register(hv_context.clk_evt[cpu],
+ HV_TIMER_FREQUENCY,
+ HV_MIN_DELTA_TICKS,
+ HV_MAX_MAX_DELTA_TICKS);
return;
}