/*
* Copyright 2004 James Cleverdon, IBM.
* Subject to the GNU Public License, v.2
*
* Flat APIC subarch code. Maximum 8 CPUs, logical delivery.
*
* Hacked for x86-64 by James Cleverdon from i386 architecture code by
* Martin Bligh, Andi Kleen, James Bottomley, John Stultz, and
* James Cleverdon.
* Ashok Raj <ashok.raj@intel.com>
* Removed IPI broadcast shortcut to support CPU hotplug
*/
#include <linux/config.h>
#include <linux/threads.h>
#include <linux/cpumask.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <asm/smp.h>
#include <asm/ipi.h>
/*
* The following permit choosing broadcast IPI shortcut v.s sending IPI only
* to online cpus via the send_IPI_mask varient.
* The mask version is my preferred option, since it eliminates a lot of
* other extra code that would need to be written to cleanup intrs sent
* to a CPU while offline.
*
* Sending broadcast introduces lots of trouble in CPU hotplug situations.
* These IPI's are delivered to cpu's irrespective of their offline status
* and could pickup stale intr data when these CPUS are turned online.
*
* Not using broadcast is a cleaner approach IMO, but Andi Kleen disagrees with
* the idea of not using broadcast IPI's anymore. Hence the run time check
* is introduced, on his request so we can choose an alternate mechanism.
*
* Initial wacky performance tests that collect cycle counts show
* no increase in using mask v.s broadcast version. In fact they seem
* identical in terms of cycle counts.
*
* if we need to use broadcast, we need to do the following.
*
* cli;
* hold call_lock;
* clear any pending IPI, just ack and clear all pending intr
* set cpu_online_map;
* release call_lock;
* sti;
*
* The complicated dummy irq processing shown above is not required if
* we didnt sent IPI's to wrong CPU's in the first place.
*
* - Ashok Raj <ashok.raj@intel.com>
*/
#ifdef CONFIG_HOTPLUG_CPU
#define DEFAULT_SEND_IPI (1)
#else
#define DEFAULT_SEND_IPI (0)
#endif
static int no_broadcast=DEFAULT_SEND_IPI;
static cpumask_t flat_target_cpus(void)
{
return cpu_online_map;
}
/*
* Set up the logical destination ID.
*
* Intel recommends to set DFR, LDR and TPR before enabling
* an APIC. See e.g. "AP-388 82489DX User's Manual" (Intel
* document number 292116). So here it goes...
*/
static void flat_init_apic_ldr(void)
{
unsigned long val;
unsigned long num, id;
num = smp_processor_id();
id = 1UL << num;
x86_cpu_to_log_apicid[num] = id;
apic_write_around(APIC_DFR, APIC_DFR_FLAT);
val = apic_read(APIC_LDR) & ~APIC_LDR_MASK;
val |= SET_APIC_LOGICAL_ID(id);
apic_write_around(APIC_LDR, val);
}
static void flat_send_IPI_mask(cpumask_t cpumask, int vector)
{
unsigned long mask = cpus_addr(cpumask)[0];
unsigned long cfg;
unsigned long flags;
local_save_flags(flags);
local_irq_disable();
/*
* Wait for idle.
*/
apic_wait_icr_idle();
/*
* prepare target chip field
*/
cfg = __prepare_ICR2(mask);
apic_write_around(APIC_ICR2, cfg);
/*
* program the ICR
*/
cfg = __prepare_ICR(0, vector, APIC_DEST_LOGICAL);
/*
* Send the IPI. The write to APIC_ICR fires this off.
*/
apic_write_around(APIC_ICR, cfg);
local_irq_restore(flags);
}
static inline void __local_flat_send_IPI_allbutself(int vector)
{
if (no_broadcast) {
cpumask_t mask = cpu_online_map;
int this_cpu = get_cpu();
cpu_clear(this_cpu, mask);
flat_send_IPI_mask(mask, vector);
put_cpu();
}
else
__send_IPI_shortcut(APIC_DEST_ALLBUT, vector, APIC_DEST_LOGICAL);
}
static inline void __local_flat_send_IPI_all(int vector)
{
if (no_broadcast)
flat_send_IPI_mask(cpu_online_map, vector);
else
__send_IPI_shortcut(APIC_DEST_ALLINC, vector, APIC_DEST_LOGICAL);
}
static void flat_send_IPI_allbutself(int vector)
{
if (((num_online_cpus()) - 1) >= 1)
__local_flat_send_IPI_allbutself(vector);
}
static void flat_send_IPI_all(int vector)
{
__local_flat_send_IPI_all(vector);
}
static int flat_apic_id_registered(void)
{
return physid_isset(GET_APIC_ID(apic_read(APIC_ID)), phys_cpu_present_map);
}
static unsigned int flat_cpu_mask_to_apicid(cpumask_t cpumask)
{
return cpus_addr(cpumask)[0] & APIC_ALL_CPUS;
}
static unsigned int phys_pkg_id(int index_msb)
{
u32 ebx;
ebx = cpuid_ebx(1);
return ((ebx >> 24) & 0xFF) >> index_msb;
}
static __init int no_ipi_broadcast(char *str)
{
get_option(&str, &no_broadcast);
printk ("Using %s mode\n", no_broadcast ? "No IPI Broadcast" :
"IPI Broadcast");
return 1;
}
__setup("no_ipi_broadcast", no_ipi_broadcast);
struct genapic apic_flat = {
.name = "flat",
.int_delivery_mode = dest_LowestPrio,
.int_dest_mode = (APIC_DEST_LOGICAL != 0),
.int_delivery_dest = APIC_DEST_LOGICAL | APIC_DM_LOWEST,
.target_cpus = flat_target_cpus,
.apic_id_registered = flat_apic_id_registered,
.init_apic_ldr = flat_init_apic_ldr,
.send_IPI_all = flat_send_IPI_all,
.send_IPI_allbutself = flat_send_IPI_allbutself,
.send_IPI_mask = flat_send_IPI_mask,
.cpu_mask_to_apicid = flat_cpu_mask_to_apicid,
.phys_pkg_id = phys_pkg_id,
};
static int __init print_ipi_mode(void)
{
printk ("Using IPI %s mode\n", no_broadcast ? "No-Shortcut" :
"Shortcut");
return 0;
}
late_initcall(print_ipi_mode);
