[stable/v4.2.y] ARM: ux500: simplify secondary CPU boot

Message ID 1445554568-4871-1-git-send-email-khilman@kernel.org
State New
Headers show

Commit Message

Kevin Hilman Oct. 22, 2015, 10:56 p.m.
From: Linus Walleij <linus.walleij@linaro.org>

This removes a lot of ancient cruft from the Ux500 SMP boot.
Instead of the pen grab/release, just point the ROM to
secondary_boot() and start the second CPU there, then send
the IPI.

Use our own SMP enable method. This enables us to remove the
last static mapping and get both CPUs booting properly.

Tested this and it just works.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>
(cherry picked from commit c00def71efd919e8ae835a25f4f4c80a4b2d36d3)
Cc: <stable@vger.kernel.org> # v4.2+
Signed-off-by: Kevin Hilman <khilman@linaro.org>
---
This patch was the 2nd in a 2-patch series.  Only the 1st patch made it
into v4.2, but this one is also needed for booting on the ste-snowball.

 arch/arm/mach-ux500/Makefile     |   2 +-
 arch/arm/mach-ux500/cpu-db8500.c |   1 -
 arch/arm/mach-ux500/headsmp.S    |  37 -----------
 arch/arm/mach-ux500/platsmp.c    | 132 ++++++++++++---------------------------
 arch/arm/mach-ux500/setup.h      |   1 -
 5 files changed, 40 insertions(+), 133 deletions(-)
 delete mode 100644 arch/arm/mach-ux500/headsmp.S

Comments

Greg KH Oct. 23, 2015, 12:17 a.m. | #1
On Thu, Oct 22, 2015 at 03:56:08PM -0700, Kevin Hilman wrote:
> From: Linus Walleij <linus.walleij@linaro.org>
> 
> This removes a lot of ancient cruft from the Ux500 SMP boot.
> Instead of the pen grab/release, just point the ROM to
> secondary_boot() and start the second CPU there, then send
> the IPI.
> 
> Use our own SMP enable method. This enables us to remove the
> last static mapping and get both CPUs booting properly.
> 
> Tested this and it just works.
> 
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> Signed-off-by: Olof Johansson <olof@lixom.net>
> (cherry picked from commit c00def71efd919e8ae835a25f4f4c80a4b2d36d3)
> Cc: <stable@vger.kernel.org> # v4.2+
> Signed-off-by: Kevin Hilman <khilman@linaro.org>
> ---
> This patch was the 2nd in a 2-patch series.  Only the 1st patch made it
> into v4.2, but this one is also needed for booting on the ste-snowball.
> 
>  arch/arm/mach-ux500/Makefile     |   2 +-
>  arch/arm/mach-ux500/cpu-db8500.c |   1 -
>  arch/arm/mach-ux500/headsmp.S    |  37 -----------
>  arch/arm/mach-ux500/platsmp.c    | 132 ++++++++++++---------------------------
>  arch/arm/mach-ux500/setup.h      |   1 -
>  5 files changed, 40 insertions(+), 133 deletions(-)
>  delete mode 100644 arch/arm/mach-ux500/headsmp.S

This looks to me like a "new feature", is it a regression from something
that used to work in 4.1?

thanks,

greg k-h
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Kevin Hilman Oct. 23, 2015, 1:15 a.m. | #2
On Thu, Oct 22, 2015 at 5:17 PM, Greg KH <greg@kroah.com> wrote:
> On Thu, Oct 22, 2015 at 03:56:08PM -0700, Kevin Hilman wrote:
>> From: Linus Walleij <linus.walleij@linaro.org>
>>
>> This removes a lot of ancient cruft from the Ux500 SMP boot.
>> Instead of the pen grab/release, just point the ROM to
>> secondary_boot() and start the second CPU there, then send
>> the IPI.
>>
>> Use our own SMP enable method. This enables us to remove the
>> last static mapping and get both CPUs booting properly.
>>
>> Tested this and it just works.
>>
>> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
>> Signed-off-by: Olof Johansson <olof@lixom.net>
>> (cherry picked from commit c00def71efd919e8ae835a25f4f4c80a4b2d36d3)
>> Cc: <stable@vger.kernel.org> # v4.2+
>> Signed-off-by: Kevin Hilman <khilman@linaro.org>
>> ---
>> This patch was the 2nd in a 2-patch series.  Only the 1st patch made it
>> into v4.2, but this one is also needed for booting on the ste-snowball.
>>
>>  arch/arm/mach-ux500/Makefile     |   2 +-
>>  arch/arm/mach-ux500/cpu-db8500.c |   1 -
>>  arch/arm/mach-ux500/headsmp.S    |  37 -----------
>>  arch/arm/mach-ux500/platsmp.c    | 132 ++++++++++++---------------------------
>>  arch/arm/mach-ux500/setup.h      |   1 -
>>  5 files changed, 40 insertions(+), 133 deletions(-)
>>  delete mode 100644 arch/arm/mach-ux500/headsmp.S
>
> This looks to me like a "new feature", is it a regression from something
> that used to work in 4.1?

I guess Linus W. will have to explain better, but I'll try...

it's the 2nd part of a 2-part fix that was submitted for v4.2, but
only the 1st part made it in because it was late for the merge window.

Kevin
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Greg KH Oct. 23, 2015, 1:22 a.m. | #3
On Thu, Oct 22, 2015 at 06:15:04PM -0700, Kevin Hilman wrote:
> On Thu, Oct 22, 2015 at 5:17 PM, Greg KH <greg@kroah.com> wrote:
> > On Thu, Oct 22, 2015 at 03:56:08PM -0700, Kevin Hilman wrote:
> >> From: Linus Walleij <linus.walleij@linaro.org>
> >>
> >> This removes a lot of ancient cruft from the Ux500 SMP boot.
> >> Instead of the pen grab/release, just point the ROM to
> >> secondary_boot() and start the second CPU there, then send
> >> the IPI.
> >>
> >> Use our own SMP enable method. This enables us to remove the
> >> last static mapping and get both CPUs booting properly.
> >>
> >> Tested this and it just works.
> >>
> >> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> >> Signed-off-by: Olof Johansson <olof@lixom.net>
> >> (cherry picked from commit c00def71efd919e8ae835a25f4f4c80a4b2d36d3)
> >> Cc: <stable@vger.kernel.org> # v4.2+
> >> Signed-off-by: Kevin Hilman <khilman@linaro.org>
> >> ---
> >> This patch was the 2nd in a 2-patch series.  Only the 1st patch made it
> >> into v4.2, but this one is also needed for booting on the ste-snowball.
> >>
> >>  arch/arm/mach-ux500/Makefile     |   2 +-
> >>  arch/arm/mach-ux500/cpu-db8500.c |   1 -
> >>  arch/arm/mach-ux500/headsmp.S    |  37 -----------
> >>  arch/arm/mach-ux500/platsmp.c    | 132 ++++++++++++---------------------------
> >>  arch/arm/mach-ux500/setup.h      |   1 -
> >>  5 files changed, 40 insertions(+), 133 deletions(-)
> >>  delete mode 100644 arch/arm/mach-ux500/headsmp.S
> >
> > This looks to me like a "new feature", is it a regression from something
> > that used to work in 4.1?
> 
> I guess Linus W. will have to explain better, but I'll try...
> 
> it's the 2nd part of a 2-part fix that was submitted for v4.2, but
> only the 1st part made it in because it was late for the merge window.

That doesn't really sound like Documentation/stable_kernel_rules.txt
material...
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Linus Walleij Oct. 23, 2015, 8:09 a.m. | #4
On Fri, Oct 23, 2015 at 3:22 AM, Greg KH <greg@kroah.com> wrote:
> On Thu, Oct 22, 2015 at 06:15:04PM -0700, Kevin Hilman wrote:
>> On Thu, Oct 22, 2015 at 5:17 PM, Greg KH <greg@kroah.com> wrote:
>> > On Thu, Oct 22, 2015 at 03:56:08PM -0700, Kevin Hilman wrote:
>> >> From: Linus Walleij <linus.walleij@linaro.org>
>> >>
>> >> This removes a lot of ancient cruft from the Ux500 SMP boot.
>> >> Instead of the pen grab/release, just point the ROM to
>> >> secondary_boot() and start the second CPU there, then send
>> >> the IPI.
>> >>
>> >> Use our own SMP enable method. This enables us to remove the
>> >> last static mapping and get both CPUs booting properly.
>> >>
>> >> Tested this and it just works.
>> >>
>> >> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
>> >> Signed-off-by: Olof Johansson <olof@lixom.net>
>> >> (cherry picked from commit c00def71efd919e8ae835a25f4f4c80a4b2d36d3)
>> >> Cc: <stable@vger.kernel.org> # v4.2+
>> >> Signed-off-by: Kevin Hilman <khilman@linaro.org>
>> >> ---
>> >> This patch was the 2nd in a 2-patch series.  Only the 1st patch made it
>> >> into v4.2, but this one is also needed for booting on the ste-snowball.
>> >>
>> >>  arch/arm/mach-ux500/Makefile     |   2 +-
>> >>  arch/arm/mach-ux500/cpu-db8500.c |   1 -
>> >>  arch/arm/mach-ux500/headsmp.S    |  37 -----------
>> >>  arch/arm/mach-ux500/platsmp.c    | 132 ++++++++++++---------------------------
>> >>  arch/arm/mach-ux500/setup.h      |   1 -
>> >>  5 files changed, 40 insertions(+), 133 deletions(-)
>> >>  delete mode 100644 arch/arm/mach-ux500/headsmp.S
>> >
>> > This looks to me like a "new feature", is it a regression from something
>> > that used to work in 4.1?
>>
>> I guess Linus W. will have to explain better, but I'll try...
>>
>> it's the 2nd part of a 2-part fix that was submitted for v4.2, but
>> only the 1st part made it in because it was late for the merge window.
>
> That doesn't really sound like Documentation/stable_kernel_rules.txt
> material...

It is. Both patches *should* have gone in the merge window, but
because of a misunderstanding and oversight, one of them were
missed, so half of the two-part solution was merged, and unfortunately
merging half of it boot-regressed the platform.

Yours,
Linus Walleij
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Patch

diff --git a/arch/arm/mach-ux500/Makefile b/arch/arm/mach-ux500/Makefile
index 4418a5078833..c8643ac5db71 100644
--- a/arch/arm/mach-ux500/Makefile
+++ b/arch/arm/mach-ux500/Makefile
@@ -7,7 +7,7 @@  obj-$(CONFIG_CACHE_L2X0)	+= cache-l2x0.o
 obj-$(CONFIG_UX500_SOC_DB8500)	+= cpu-db8500.o
 obj-$(CONFIG_MACH_MOP500)	+= board-mop500-regulators.o \
 				board-mop500-audio.o
-obj-$(CONFIG_SMP)		+= platsmp.o headsmp.o
+obj-$(CONFIG_SMP)		+= platsmp.o
 obj-$(CONFIG_HOTPLUG_CPU)	+= hotplug.o
 obj-$(CONFIG_PM_GENERIC_DOMAINS) += pm_domains.o
 
diff --git a/arch/arm/mach-ux500/cpu-db8500.c b/arch/arm/mach-ux500/cpu-db8500.c
index 16913800bbf9..ba708ce08616 100644
--- a/arch/arm/mach-ux500/cpu-db8500.c
+++ b/arch/arm/mach-ux500/cpu-db8500.c
@@ -154,7 +154,6 @@  static const char * stericsson_dt_platform_compat[] = {
 };
 
 DT_MACHINE_START(U8500_DT, "ST-Ericsson Ux5x0 platform (Device Tree Support)")
-	.smp            = smp_ops(ux500_smp_ops),
 	.map_io		= u8500_map_io,
 	.init_irq	= ux500_init_irq,
 	/* we re-use nomadik timer here */
diff --git a/arch/arm/mach-ux500/headsmp.S b/arch/arm/mach-ux500/headsmp.S
deleted file mode 100644
index 9cdea049485d..000000000000
--- a/arch/arm/mach-ux500/headsmp.S
+++ /dev/null
@@ -1,37 +0,0 @@ 
-/*
- *  Copyright (c) 2009 ST-Ericsson
- *	This file is based  ARM Realview platform
- *  Copyright (c) 2003 ARM Limited
- *  All Rights Reserved
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
-#include <linux/linkage.h>
-#include <linux/init.h>
-
-/*
- * U8500 specific entry point for secondary CPUs.
- */
-ENTRY(u8500_secondary_startup)
-	mrc	p15, 0, r0, c0, c0, 5
-	and	r0, r0, #15
-	adr	r4, 1f
-	ldmia	r4, {r5, r6}
-	sub	r4, r4, r5
-	add	r6, r6, r4
-pen:	ldr	r7, [r6]
-	cmp	r7, r0
-	bne	pen
-
-	/*
-	 * we've been released from the holding pen: secondary_stack
-	 * should now contain the SVC stack for this core
-	 */
-	b	secondary_startup
-ENDPROC(u8500_secondary_startup)
-
-	.align 2
-1:	.long	.
-	.long	pen_release
diff --git a/arch/arm/mach-ux500/platsmp.c b/arch/arm/mach-ux500/platsmp.c
index 62b1de922bd8..70766b963758 100644
--- a/arch/arm/mach-ux500/platsmp.c
+++ b/arch/arm/mach-ux500/platsmp.c
@@ -28,135 +28,81 @@ 
 #include "db8500-regs.h"
 #include "id.h"
 
-static void __iomem *scu_base;
-static void __iomem *backupram;
-
-/* This is called from headsmp.S to wakeup the secondary core */
-extern void u8500_secondary_startup(void);
-
-/*
- * Write pen_release in a way that is guaranteed to be visible to all
- * observers, irrespective of whether they're taking part in coherency
- * or not.  This is necessary for the hotplug code to work reliably.
- */
-static void write_pen_release(int val)
-{
-	pen_release = val;
-	smp_wmb();
-	sync_cache_w(&pen_release);
-}
-
-static DEFINE_SPINLOCK(boot_lock);
-
-static void ux500_secondary_init(unsigned int cpu)
-{
-	/*
-	 * let the primary processor know we're out of the
-	 * pen, then head off into the C entry point
-	 */
-	write_pen_release(-1);
-
-	/*
-	 * Synchronise with the boot thread.
-	 */
-	spin_lock(&boot_lock);
-	spin_unlock(&boot_lock);
-}
+/* Magic triggers in backup RAM */
+#define UX500_CPU1_JUMPADDR_OFFSET 0x1FF4
+#define UX500_CPU1_WAKEMAGIC_OFFSET 0x1FF0
 
-static int ux500_boot_secondary(unsigned int cpu, struct task_struct *idle)
+static void wakeup_secondary(void)
 {
-	unsigned long timeout;
-
-	/*
-	 * set synchronisation state between this boot processor
-	 * and the secondary one
-	 */
-	spin_lock(&boot_lock);
-
-	/*
-	 * The secondary processor is waiting to be released from
-	 * the holding pen - release it, then wait for it to flag
-	 * that it has been released by resetting pen_release.
-	 */
-	write_pen_release(cpu_logical_map(cpu));
-
-	arch_send_wakeup_ipi_mask(cpumask_of(cpu));
+	struct device_node *np;
+	static void __iomem *backupram;
 
-	timeout = jiffies + (1 * HZ);
-	while (time_before(jiffies, timeout)) {
-		if (pen_release == -1)
-			break;
+	np = of_find_compatible_node(NULL, NULL, "ste,dbx500-backupram");
+	if (!np) {
+		pr_err("No backupram base address\n");
+		return;
+	}
+	backupram = of_iomap(np, 0);
+	of_node_put(np);
+	if (!backupram) {
+		pr_err("No backupram remap\n");
+		return;
 	}
 
 	/*
-	 * now the secondary core is starting up let it run its
-	 * calibrations, then wait for it to finish
-	 */
-	spin_unlock(&boot_lock);
-
-	return pen_release != -1 ? -ENOSYS : 0;
-}
-
-static void __init wakeup_secondary(void)
-{
-	/*
 	 * write the address of secondary startup into the backup ram register
 	 * at offset 0x1FF4, then write the magic number 0xA1FEED01 to the
 	 * backup ram register at offset 0x1FF0, which is what boot rom code
-	 * is waiting for. This would wake up the secondary core from WFE
+	 * is waiting for. This will wake up the secondary core from WFE.
 	 */
-#define UX500_CPU1_JUMPADDR_OFFSET 0x1FF4
-	__raw_writel(virt_to_phys(u8500_secondary_startup),
-		     backupram + UX500_CPU1_JUMPADDR_OFFSET);
-
-#define UX500_CPU1_WAKEMAGIC_OFFSET 0x1FF0
-	__raw_writel(0xA1FEED01,
-		     backupram + UX500_CPU1_WAKEMAGIC_OFFSET);
+	writel(virt_to_phys(secondary_startup),
+	       backupram + UX500_CPU1_JUMPADDR_OFFSET);
+	writel(0xA1FEED01,
+	       backupram + UX500_CPU1_WAKEMAGIC_OFFSET);
 
 	/* make sure write buffer is drained */
 	mb();
+	iounmap(backupram);
 }
 
-/*
- * Initialise the CPU possible map early - this describes the CPUs
- * which may be present or become present in the system.
- */
-static void __init ux500_smp_init_cpus(void)
+static void __init ux500_smp_prepare_cpus(unsigned int max_cpus)
 {
-	unsigned int i, ncores;
 	struct device_node *np;
+	static void __iomem *scu_base;
+	unsigned int ncores;
+	int i;
 
 	np = of_find_compatible_node(NULL, NULL, "arm,cortex-a9-scu");
+	if (!np) {
+		pr_err("No SCU base address\n");
+		return;
+	}
 	scu_base = of_iomap(np, 0);
 	of_node_put(np);
-	if (!scu_base)
+	if (!scu_base) {
+		pr_err("No SCU remap\n");
 		return;
-	backupram = ioremap(U8500_BACKUPRAM0_BASE, SZ_8K);
-	ncores = scu_get_core_count(scu_base);
-
-	/* sanity check */
-	if (ncores > nr_cpu_ids) {
-		pr_warn("SMP: %u cores greater than maximum (%u), clipping\n",
-			ncores, nr_cpu_ids);
-		ncores = nr_cpu_ids;
 	}
 
+	scu_enable(scu_base);
+	ncores = scu_get_core_count(scu_base);
 	for (i = 0; i < ncores; i++)
 		set_cpu_possible(i, true);
+	iounmap(scu_base);
 }
 
-static void __init ux500_smp_prepare_cpus(unsigned int max_cpus)
+static int ux500_boot_secondary(unsigned int cpu, struct task_struct *idle)
 {
-	scu_enable(scu_base);
 	wakeup_secondary();
+	arch_send_wakeup_ipi_mask(cpumask_of(cpu));
+	return 0;
 }
 
 struct smp_operations ux500_smp_ops __initdata = {
-	.smp_init_cpus		= ux500_smp_init_cpus,
 	.smp_prepare_cpus	= ux500_smp_prepare_cpus,
-	.smp_secondary_init	= ux500_secondary_init,
 	.smp_boot_secondary	= ux500_boot_secondary,
 #ifdef CONFIG_HOTPLUG_CPU
 	.cpu_die		= ux500_cpu_die,
 #endif
 };
+CPU_METHOD_OF_DECLARE(ux500_smp, "ste,dbx500-smp", &ux500_smp_ops);
diff --git a/arch/arm/mach-ux500/setup.h b/arch/arm/mach-ux500/setup.h
index 1fb6ad2789f1..65876eac0761 100644
--- a/arch/arm/mach-ux500/setup.h
+++ b/arch/arm/mach-ux500/setup.h
@@ -26,7 +26,6 @@  extern struct device *ux500_soc_device_init(const char *soc_id);
 
 extern void ux500_timer_init(void);
 
-extern struct smp_operations ux500_smp_ops;
 extern void ux500_cpu_die(unsigned int cpu);
 
 #endif /*  __ASM_ARCH_SETUP_H */