[PATCH v3 6/6] powerpc/mpc85xx: Add CPU hotplug support for E6500
Chenhui Zhao
chenhui.zhao at freescale.com
Fri Nov 20 20:14:02 AEDT 2015
Support Freescale E6500 core-based platforms, like t4240.
Support disabling/enabling individual CPU thread dynamically.
Signed-off-by: Chenhui Zhao <chenhui.zhao at freescale.com>
---
changes for v3
* rebase patches on the latest code
* add const for info in wake_hw_thread()
* use r8 instead of r13 in the assemble code
* added some comments in code
* checked SPRN_BUCSR to see whether the current thread has been initialized
* changed the flow in smp_85xx_kick_cpu()
* changed that the code to start thread in generic_secondary_smp_init does not depend
on which thread it is running
major changes for v2:
* start Thread1 by Thread0 when we want to boot Thread1 only replacing
the method of changing cpu physical id
arch/powerpc/include/asm/cputhreads.h | 6 +++
arch/powerpc/include/asm/smp.h | 1 +
arch/powerpc/kernel/head_64.S | 78 +++++++++++++++++++++++++++++++++++
arch/powerpc/platforms/85xx/smp.c | 70 +++++++++++++++++--------------
4 files changed, 124 insertions(+), 31 deletions(-)
diff --git a/arch/powerpc/include/asm/cputhreads.h b/arch/powerpc/include/asm/cputhreads.h
index e5a769d..9ec41e5 100644
--- a/arch/powerpc/include/asm/cputhreads.h
+++ b/arch/powerpc/include/asm/cputhreads.h
@@ -1,6 +1,7 @@
#ifndef _ASM_POWERPC_CPUTHREADS_H
#define _ASM_POWERPC_CPUTHREADS_H
+#ifndef __ASSEMBLY__
#include <linux/cpumask.h>
/*
@@ -102,7 +103,12 @@ static inline u32 get_tensr(void)
return 1;
}
+void book3e_start_thread(int thread, unsigned long addr);
void book3e_stop_thread(int thread);
+#endif /* __ASSEMBLY__ */
+
+#define INVALID_THREAD_HWID 0x0fff
+
#endif /* _ASM_POWERPC_CPUTHREADS_H */
diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index bdb8111..174271e 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -200,6 +200,7 @@ extern void generic_secondary_thread_init(void);
extern unsigned long __secondary_hold_spinloop;
extern unsigned long __secondary_hold_acknowledge;
extern char __secondary_hold;
+extern unsigned int booting_thread_hwid;
extern void __early_start(void);
#endif /* __ASSEMBLY__ */
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 6036253..2916283 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -40,6 +40,7 @@
#include <asm/kvm_book3s_asm.h>
#include <asm/ptrace.h>
#include <asm/hw_irq.h>
+#include <asm/cputhreads.h>
/* The physical memory is laid out such that the secondary processor
* spin code sits at 0x0000...0x00ff. On server, the vectors follow
@@ -182,6 +183,45 @@ exception_marker:
#ifdef CONFIG_PPC_BOOK3E
/*
+ * The booting_thread_hwid holds the thread id we want to boot in cpu
+ * hotplug case. It is set by cpu hotplug code, and is invalid by default.
+ * The thread id is the same as the initial value of SPRN_PIR[THREAD_ID]
+ * bit field.
+ */
+ .globl booting_thread_hwid
+booting_thread_hwid:
+ .long INVALID_THREAD_HWID
+ .align 3
+/*
+ * start a thread in the same core
+ * input parameters:
+ * r3 = the thread physical id
+ * r4 = the entry point where thread starts
+ */
+_GLOBAL(book3e_start_thread)
+ LOAD_REG_IMMEDIATE(r5, MSR_KERNEL)
+ cmpi 0, r3, 0
+ beq 10f
+ cmpi 0, r3, 1
+ beq 11f
+ /* If the thread id is invalid, just exit. */
+ b 13f
+10:
+ mttmr TMRN_IMSR0, r5
+ mttmr TMRN_INIA0, r4
+ b 12f
+11:
+ mttmr TMRN_IMSR1, r5
+ mttmr TMRN_INIA1, r4
+12:
+ isync
+ li r6, 1
+ sld r6, r6, r3
+ mtspr SPRN_TENS, r6
+13:
+ blr
+
+/*
* stop a thread in the same core
* input parameter:
* r3 = the thread physical id
@@ -280,6 +320,44 @@ _GLOBAL(generic_secondary_smp_init)
mr r3,r24
mr r4,r25
bl book3e_secondary_core_init
+
+/*
+ * After common core init has finished, check if the current thread is the
+ * one we wanted to boot. If not, start the specified thread and stop the
+ * current thread.
+ */
+ LOAD_REG_ADDR(r4, booting_thread_hwid)
+ lwz r3, 0(r4)
+ li r5, INVALID_THREAD_HWID
+ cmpw r3, r5
+ beq 20f
+
+ /*
+ * The value of booting_thread_hwid has been stored in r3,
+ * so make it invalid.
+ */
+ stw r5, 0(r4)
+
+ /*
+ * Get the current thread id and check if it is the one we wanted.
+ * If not, start the one specified in booting_thread_hwid and stop
+ * the current thread.
+ */
+ mfspr r8, SPRN_TIR
+ cmpw r3, r8
+ beq 20f
+
+ /* start the specified thread */
+ LOAD_REG_ADDR(r5, fsl_secondary_thread_init)
+ ld r4, 0(r5)
+ bl book3e_start_thread
+
+ /* stop the current thread */
+ mr r3, r8
+ bl book3e_stop_thread
+10:
+ b 10b
+20:
#endif
generic_secondary_common_init:
diff --git a/arch/powerpc/platforms/85xx/smp.c b/arch/powerpc/platforms/85xx/smp.c
index 0f56dd5..cc22737 100644
--- a/arch/powerpc/platforms/85xx/smp.c
+++ b/arch/powerpc/platforms/85xx/smp.c
@@ -182,24 +182,11 @@ static inline u32 read_spin_table_addr_l(void *spin_table)
static void wake_hw_thread(void *info)
{
void fsl_secondary_thread_init(void);
- unsigned long imsr, inia;
- int nr = *(const int *)info;
+ unsigned long inia;
+ int cpu = *(const int *)info;
- imsr = MSR_KERNEL;
inia = *(unsigned long *)fsl_secondary_thread_init;
-
- if (cpu_thread_in_core(nr) == 0) {
- /* For when we boot on a secondary thread with kdump */
- mttmr(TMRN_IMSR0, imsr);
- mttmr(TMRN_INIA0, inia);
- mtspr(SPRN_TENS, TEN_THREAD(0));
- } else {
- mttmr(TMRN_IMSR1, imsr);
- mttmr(TMRN_INIA1, inia);
- mtspr(SPRN_TENS, TEN_THREAD(1));
- }
-
- smp_generic_kick_cpu(nr);
+ book3e_start_thread(cpu_thread_in_core(cpu), inia);
}
#endif
@@ -294,33 +281,54 @@ static int smp_85xx_kick_cpu(int nr)
pr_debug("kick CPU #%d\n", nr);
#ifdef CONFIG_PPC64
- /* Threads don't use the spin table */
- if (cpu_thread_in_core(nr) != 0) {
- int primary = cpu_first_thread_sibling(nr);
-
+ if (threads_per_core == 2) {
if (WARN_ON_ONCE(!cpu_has_feature(CPU_FTR_SMT)))
return -ENOENT;
- if (cpu_thread_in_core(nr) != 1) {
- pr_err("%s: cpu %d: invalid hw thread %d\n",
- __func__, nr, cpu_thread_in_core(nr));
- return -ENOENT;
- }
+ booting_thread_hwid = cpu_thread_in_core(nr);
+ primary = cpu_first_thread_sibling(nr);
- if (!cpu_online(primary)) {
- pr_err("%s: cpu %d: primary %d not online\n",
- __func__, nr, primary);
- return -ENOENT;
+ if (qoriq_pm_ops)
+ qoriq_pm_ops->cpu_up_prepare(nr);
+
+ /*
+ * If either thread in the core is online, use it to start
+ * the other.
+ */
+ if (cpu_online(primary)) {
+ smp_call_function_single(primary,
+ wake_hw_thread, &nr, 1);
+ goto done;
+ } else if (cpu_online(primary + 1)) {
+ smp_call_function_single(primary + 1,
+ wake_hw_thread, &nr, 1);
+ goto done;
}
- smp_call_function_single(primary, wake_hw_thread, &nr, 0);
- return 0;
+ /*
+ * If getting here, it means both threads in the core are
+ * offline. So start the primary thread, then it will start
+ * the thread specified in booting_thread_hwid, the one
+ * corresponding to nr.
+ */
+
+ } else if (threads_per_core == 1) {
+ /*
+ * If one core has only one thread, set booting_thread_hwid to
+ * an invalid value.
+ */
+ booting_thread_hwid = INVALID_THREAD_HWID;
+
+ } else if (threads_per_core > 2) {
+ pr_err("Do not support more than 2 threads per CPU.");
+ return -EINVAL;
}
ret = smp_85xx_start_cpu(primary);
if (ret)
return ret;
+done:
paca[nr].cpu_start = 1;
generic_set_cpu_up(nr);
--
1.9.1
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