[PATCH] x86/platform/uv: HUB RTC cleanup

[PATCH] x86/platform/uv: HUB RTC cleanup

[Dimitri Sivanich]

Remove unused event code and other cleanup for HUB RTC.

Signed-off-by: Dimitri Sivanich <sivanich@hpe.com>
---
 arch/x86/platform/uv/uv_time.c | 362 +----------------------------------------
 1 file changed, 8 insertions(+), 354 deletions(-)

diff --git a/arch/x86/platform/uv/uv_time.c b/arch/x86/platform/uv/uv_time.c
index 7af31b245636..1777b7164ff8 100644
--- a/arch/x86/platform/uv/uv_time.c
+++ b/arch/x86/platform/uv/uv_time.c
@@ -1,25 +1,18 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
- * SGI RTC clock/timer routines.
+ * HPE RTC clock routine.
  *
+ *  Copyright (C) 2020 Hewlett Packard Enterprise, All rights reserved.
  *  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"
+#define RTC_NAME		"hub_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,
@@ -29,325 +22,23 @@ static struct clocksource clocksource_uv = {
 	.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[1];
-};
-
-/*
- * 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);
-	apicid |= uv_apicid_hibits;
-	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)
-{
-	if (is_uv1_hub())
-		return uv_read_global_mmr64(pnode, UVH_EVENT_OCCURRED0) &
-			UV1H_EVENT_OCCURRED0_RTC1_MASK;
-	else if (is_uvx_hub())
-		return uv_read_global_mmr64(pnode, UVXH_EVENT_OCCURRED2) &
-			UVXH_EVENT_OCCURRED2_RTC_1_MASK;
-	return 0;
-}
-
-/* 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) | uv_apicid_hibits;
-	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);
-
-	if (is_uv1_hub())
-		uv_write_global_mmr64(pnode, UVH_EVENT_OCCURRED0_ALIAS,
-				UV1H_EVENT_OCCURRED0_RTC1_MASK);
-	else
-		uv_write_global_mmr64(pnode, UVXH_EVENT_OCCURRED2_ALIAS,
-				UVXH_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(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_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.
+ * cachelines of its 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;
+	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;
@@ -357,47 +48,10 @@ static __init int uv_rtc_setup_clock(void)
 
 	rc = clocksource_register_hz(&clocksource_uv, sn_rtc_cycles_per_second);
 	if (rc)
-		printk(KERN_INFO "UV RTC clocksource failed rc %d\n", rc);
+		pr_info("HUB RTC clocksource failed rc %d\n", rc);
 	else
-		printk(KERN_INFO "UV RTC clocksource registered freq %lu MHz\n",
+		pr_info("HUB 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);
-- 
2.12.3

Re: [PATCH] x86/platform/uv: HUB RTC cleanup

[Christoph Hellwig]

On Mon, May 11, 2020 at 05:35:35PM -0500, Dimitri Sivanich wrote:
> Remove unused event code and other cleanup for HUB RTC.

Can you explain how this is dead?  That's not entirely obvious
from the patch.  Also you probably want to split it the cleans
into one or several additional patches and aso document them in
the commit log(s).

> diff --git a/arch/x86/platform/uv/uv_time.c b/arch/x86/platform/uv/uv_time.c
> index 7af31b245636..1777b7164ff8 100644
> --- a/arch/x86/platform/uv/uv_time.c
> +++ b/arch/x86/platform/uv/uv_time.c
> @@ -1,25 +1,18 @@
>  // SPDX-License-Identifier: GPL-2.0-or-later
>  /*
> - * SGI RTC clock/timer routines.
> + * HPE RTC clock routine.

Might be worth mentioning this is for the UV platform?  Both the
old SGI and thew new HPE are not very descriptive.