Blackfin: SMP: add PM/CPU hotplug support

Signed-off-by: Graf Yang <graf.yang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/Kconfig

@@ -250,6 +250,11 @@ config NR_CPUS
 	depends on SMP
 	default 2 if BF561
 
+config HOTPLUG_CPU
+	bool "Support for hot-pluggable CPUs"
+	depends on SMP && HOTPLUG
+	default y
+
 config IRQ_PER_CPU
 	bool
 	depends on SMP
@@ -1130,7 +1135,6 @@ source "fs/Kconfig.binfmt"
 endmenu
 
 menu "Power management options"
-	depends on !SMP
 
 source "kernel/power/Kconfig"
 

arch/blackfin/include/asm/smp.h

@@ -25,5 +25,12 @@ struct corelock_slot {
 
 void smp_icache_flush_range_others(unsigned long start,
 				   unsigned long end);
+#ifdef CONFIG_HOTPLUG_CPU
+void coreb_sleep(u32 sic_iwr0, u32 sic_iwr1, u32 sic_iwr2);
+void cpu_die(void);
+void platform_cpu_die(void);
+int __cpu_disable(void);
+int __cpu_die(unsigned int cpu);
+#endif
 
 #endif /* !__ASM_BLACKFIN_SMP_H */

arch/blackfin/mach-bf561/Makefile

@@ -6,3 +6,4 @@ obj-y := ints-priority.o dma.o
 
 obj-$(CONFIG_BF561_COREB) += coreb.o
 obj-$(CONFIG_SMP)  += smp.o secondary.o atomic.o
+obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o

arch/blackfin/mach-bf561/hotplug.c

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2007-2009 Analog Devices Inc.
+ *               Graff Yang <graf.yang@analog.com>
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <asm/blackfin.h>
+#include <asm/smp.h>
+#define SIC_SYSIRQ(irq)	(irq - (IRQ_CORETMR + 1))
+
+int hotplug_coreb;
+
+void platform_cpu_die(void)
+{
+	unsigned long iwr[2] = {0, 0};
+	unsigned long bank = SIC_SYSIRQ(IRQ_SUPPLE_0) / 32;
+	unsigned long bit = 1 << (SIC_SYSIRQ(IRQ_SUPPLE_0) % 32);
+
+	hotplug_coreb = 1;
+
+	iwr[bank] = bit;
+
+	/* disable core timer */
+	bfin_write_TCNTL(0);
+
+	/* clear ipi interrupt IRQ_SUPPLE_0 */
+	bfin_write_SICB_SYSCR(bfin_read_SICB_SYSCR() | (1 << (10 + 1)));
+	SSYNC();
+
+	coreb_sleep(iwr[0], iwr[1], 0);
+}

arch/blackfin/mach-bf561/secondary.S

@@ -11,6 +11,7 @@
 #include <linux/init.h>
 #include <asm/blackfin.h>
 #include <asm/asm-offsets.h>
+#include <asm/trace.h>
 
 __INIT
 
@@ -62,6 +63,8 @@ ENTRY(_coreb_trampoline_start)
 	M2 = r0;
 	M3 = r0;
 
+	trace_buffer_init(p0,r0);
+
 	/* Turn off the icache */
 	p0.l = LO(IMEM_CONTROL);
 	p0.h = HI(IMEM_CONTROL);
@@ -159,6 +162,41 @@ ENTRY(_coreb_trampoline_start)
 ENDPROC(_coreb_trampoline_start)
 ENTRY(_coreb_trampoline_end)
 
+.section ".text"
+ENTRY(_set_sicb_iwr)
+	P0.H = hi(SICB_IWR0);
+	P0.L = lo(SICB_IWR0);
+	P1.H = hi(SICB_IWR1);
+	P1.L = lo(SICB_IWR1);
+	[P0] = R0;
+	[P1] = R1;
+	SSYNC;
+	RTS;
+ENDPROC(_set_sicb_iwr)
+
+ENTRY(_coreb_sleep)
+	sp.l = lo(INITIAL_STACK);
+	sp.h = hi(INITIAL_STACK);
+	fp = sp;
+	usp = sp;
+
+	call _set_sicb_iwr;
+
+	CLI R2;
+	SSYNC;
+	IDLE;
+	STI R2;
+
+	R0 = IWR_DISABLE_ALL;
+	R1 = IWR_DISABLE_ALL;
+	call _set_sicb_iwr;
+
+	p0.h = hi(COREB_L1_CODE_START);
+	p0.l = lo(COREB_L1_CODE_START);
+	jump (p0);
+ENDPROC(_coreb_sleep)
+
+__CPUINIT
 ENTRY(_coreb_start)
 	[--sp] = reti;
 
@@ -176,12 +214,20 @@ ENTRY(_coreb_start)
 	sp = [p0];
 	usp = sp;
 	fp = sp;
+#ifdef CONFIG_HOTPLUG_CPU
+	p0.l = _hotplug_coreb;
+	p0.h = _hotplug_coreb;
+	r0 = [p0];
+	cc = BITTST(r0, 0);
+	if cc jump 3f;
+#endif
 	sp += -12;
 	call _init_pda
 	sp += 12;
+#ifdef CONFIG_HOTPLUG_CPU
+3:
+#endif
 	call _secondary_start_kernel;
 .L_exit:
 	jump.s	.L_exit;
 ENDPROC(_coreb_start)
-
-__FINIT

arch/blackfin/mach-bf561/smp.c

@@ -65,6 +65,8 @@ void __cpuinit platform_secondary_init(unsigned int cpu)
 	bfin_write_SICB_IAR5(bfin_read_SICA_IAR5());
 	bfin_write_SICB_IAR6(bfin_read_SICA_IAR6());
 	bfin_write_SICB_IAR7(bfin_read_SICA_IAR7());
+	bfin_write_SICB_IWR0(IWR_DISABLE_ALL);
+	bfin_write_SICB_IWR1(IWR_DISABLE_ALL);
 	SSYNC();
 
 	/* Store CPU-private information to the cpu_data array. */
@@ -80,17 +82,18 @@ int __cpuinit platform_boot_secondary(unsigned int cpu, struct task_struct *idle
 {
 	unsigned long timeout;
 
-	/* CoreB already running?! */
-	BUG_ON((bfin_read_SICA_SYSCR() & COREB_SRAM_INIT) == 0);
-
 	printk(KERN_INFO "Booting Core B.\n");
 
 	spin_lock(&boot_lock);
 
-	/* Kick CoreB, which should start execution from CORE_SRAM_BASE. */
-	SSYNC();
-	bfin_write_SICA_SYSCR(bfin_read_SICA_SYSCR() & ~COREB_SRAM_INIT);
-	SSYNC();
+	if ((bfin_read_SICA_SYSCR() & COREB_SRAM_INIT) == 0) {
+		/* CoreB already running, sending ipi to wakeup it */
+		platform_send_ipi_cpu(cpu, IRQ_SUPPLE_0);
+	} else {
+		/* Kick CoreB, which should start execution from CORE_SRAM_BASE. */
+		bfin_write_SICA_SYSCR(bfin_read_SICA_SYSCR() & ~COREB_SRAM_INIT);
+		SSYNC();
+	}
 
 	timeout = jiffies + 1 * HZ;
 	while (time_before(jiffies, timeout)) {

arch/blackfin/mach-common/smp.c

@@ -344,8 +344,11 @@ void smp_send_stop(void)
 
 int __cpuinit __cpu_up(unsigned int cpu)
 {
-	struct task_struct *idle;
 	int ret;
+	static struct task_struct *idle;
+
+	if (idle)
+		free_task(idle);
 
 	idle = fork_idle(cpu);
 	if (IS_ERR(idle)) {
@@ -354,7 +357,6 @@ int __cpuinit __cpu_up(unsigned int cpu)
 	}
 
 	secondary_stack = task_stack_page(idle) + THREAD_SIZE;
-	smp_wmb();
 
 	ret = platform_boot_secondary(cpu, idle);
 
@@ -413,7 +415,6 @@ void __cpuinit secondary_start_kernel(void)
 	atomic_inc(&mm->mm_users);
 	atomic_inc(&mm->mm_count);
 	current->active_mm = mm;
-	BUG_ON(current->mm);	/* Can't be, but better be safe than sorry. */
 
 	preempt_disable();
 
@@ -495,3 +496,34 @@ void resync_core_dcache(void)
 }
 EXPORT_SYMBOL(resync_core_dcache);
 #endif
+
+#ifdef CONFIG_HOTPLUG_CPU
+int __cpuexit __cpu_disable(void)
+{
+	unsigned int cpu = smp_processor_id();
+
+	if (cpu == 0)
+		return -EPERM;
+
+	set_cpu_online(cpu, false);
+	return 0;
+}
+
+static DECLARE_COMPLETION(cpu_killed);
+
+int __cpuexit __cpu_die(unsigned int cpu)
+{
+	return wait_for_completion_timeout(&cpu_killed, 5000);
+}
+
+void cpu_die(void)
+{
+	complete(&cpu_killed);
+
+	atomic_dec(&init_mm.mm_users);
+	atomic_dec(&init_mm.mm_count);
+
+	local_irq_disable();
+	platform_cpu_die();
+}
+#endif