[PATCH 0/2] Add code to release secondary cores from holding pen.

[PATCH 0/2] Add code to release secondary cores from holding pen.

[Peter Griffin]

Hi Maxime,

This patchset adds in the necessary code to manage the holding pen for STi
platforms.

Due to all the STi upstream devs using JTAG to boot the STi boards, there
is currently a SMP bug when booting upstream kernels via u-boot where
only the primary core is brought up.

This hasn't been noticed until now because when booting via JTAG the
stlinux_arm_boot script sets the PC of the secondary cores directly.

I can't test this on a STiH418 platform, as I don't have one, but a similar
DT change will be required there as well. I'm not sure if u-boot uses
the same SBC DMEM offset by default or not.

With these patches applied booting via u-boot now works correctly.

[    0.045456] CPU: Testing write buffer coherency: ok
[    0.045597] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
[    0.045734] Setting up static identity map for 0x40209000 - 0x40209098
[    0.065047] CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
[    0.065081] Brought up 2 CPUs
[    0.065089] SMP: Total of 2 processors activated (5983.43 BogoMIPS).
[    0.065092] CPU: All CPU(s) started in SVC mode.

IMHO these should be considered for the next -rc.

regards,

Peter.

Peter Griffin (2):
  ARM: STi: Add code to release secondary cores from holding pen.
  ARM: STi: DT: STiH407: Add cpu-release-addr dt property.

 arch/arm/boot/dts/stih407-family.dtsi |  4 +++
 arch/arm/mach-sti/headsmp.S           |  1 +
 arch/arm/mach-sti/platsmp.c           | 56 +++++++++++++++++++++++++++++++++--
 arch/arm/mach-sti/smp.h               |  2 ++
 4 files changed, 60 insertions(+), 3 deletions(-)

-- 
1.9.1

[PATCH 1/2] ARM: STi: Add code to release secondary cores from holding pen.

[Peter Griffin]

Most upstream devs boot STi platform via JTAG which abuses the
boot process by setting the PC of secondary cores directly. As
a consquence, booting STi platforms via u-boot results in only
the primary core being brought up as the code to manage the
holding pen is not upstream.

This patch adds the necessary code to bring the secondary cores
out of the holding pen. It uses the cpu-release-addr DT property
to get the address of the holding pen from the bootloader.

With this patch booting upstream kernels via u-boot works
correctly:

[    0.045456] CPU: Testing write buffer coherency: ok
[    0.045597] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
[    0.045734] Setting up static identity map for 0x40209000 - 0x40209098
[    0.065047] CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
[    0.065081] Brought up 2 CPUs
[    0.065089] SMP: Total of 2 processors activated (5983.43 BogoMIPS).
[    0.065092] CPU: All CPU(s) started in SVC mode.

Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
---
 arch/arm/mach-sti/headsmp.S |  1 +
 arch/arm/mach-sti/platsmp.c | 56 ++++++++++++++++++++++++++++++++++++++++++---
 arch/arm/mach-sti/smp.h     |  2 ++
 3 files changed, 56 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mach-sti/headsmp.S b/arch/arm/mach-sti/headsmp.S
index 4c09bae..e0ad4517 100644
--- a/arch/arm/mach-sti/headsmp.S
+++ b/arch/arm/mach-sti/headsmp.S
@@ -37,6 +37,7 @@ pen:	ldr	r7, [r6]
 	 * should now contain the SVC stack for this core
 	 */
 	b	secondary_startup
+ENDPROC(sti_secondary_startup)
 
 1:	.long	.
 	.long	pen_release
diff --git a/arch/arm/mach-sti/platsmp.c b/arch/arm/mach-sti/platsmp.c
index d4b624f..6597ed8 100644
--- a/arch/arm/mach-sti/platsmp.c
+++ b/arch/arm/mach-sti/platsmp.c
@@ -20,6 +20,7 @@
 #include <linux/io.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
+#include <linux/memblock.h>
 
 #include <asm/cacheflush.h>
 #include <asm/smp_plat.h>
@@ -99,14 +100,62 @@ static int sti_boot_secondary(unsigned int cpu, struct task_struct *idle)
 
 static void __init sti_smp_prepare_cpus(unsigned int max_cpus)
 {
-	void __iomem *scu_base = NULL;
-	struct device_node *np = of_find_compatible_node(
-					NULL, NULL, "arm,cortex-a9-scu");
+	struct device_node *np;
+	void __iomem *scu_base;
+	u32 __iomem *cpu_strt_ptr;
+	u32 release_phys;
+	int cpu;
+	unsigned long entry_pa = virt_to_phys(sti_secondary_startup);
+
+	np = of_find_compatible_node(NULL, NULL, "arm,cortex-a9-scu");
+
 	if (np) {
 		scu_base = of_iomap(np, 0);
 		scu_enable(scu_base);
 		of_node_put(np);
 	}
+
+	if (max_cpus <= 1)
+		return;
+
+	for_each_possible_cpu(cpu) {
+
+		np = of_get_cpu_node(cpu, NULL);
+
+		if (!np)
+			continue;
+
+		if (of_property_read_u32(np, "cpu-release-addr",
+						&release_phys)) {
+			pr_err("CPU %d: missing or invalid cpu-release-addr "
+				"property\n", cpu);
+			continue;
+		}
+
+		/*
+		 * holding pen is usually configured in SBC DMEM but can also be
+		 * in RAM.
+		 */
+
+		if (!memblock_is_memory(release_phys))
+			cpu_strt_ptr =
+				ioremap(release_phys, sizeof(release_phys));
+		else
+			cpu_strt_ptr =
+				(u32 __iomem *)phys_to_virt(release_phys);
+
+		__raw_writel(entry_pa, cpu_strt_ptr);
+
+		/*
+		 * wmb so that data is actually written
+		 * before cache flush is done
+		 */
+		smp_wmb();
+		sync_cache_w(cpu_strt_ptr);
+
+		if (!memblock_is_memory(release_phys))
+			iounmap(cpu_strt_ptr);
+	}
 }
 
 struct smp_operations __initdata sti_smp_ops = {
@@ -114,3 +163,4 @@ struct smp_operations __initdata sti_smp_ops = {
 	.smp_secondary_init	= sti_secondary_init,
 	.smp_boot_secondary	= sti_boot_secondary,
 };
+
diff --git a/arch/arm/mach-sti/smp.h b/arch/arm/mach-sti/smp.h
index 1871b72..ae22707 100644
--- a/arch/arm/mach-sti/smp.h
+++ b/arch/arm/mach-sti/smp.h
@@ -14,4 +14,6 @@
 
 extern struct smp_operations	sti_smp_ops;
 
+void sti_secondary_startup(void);
+
 #endif
-- 
1.9.1

[PATCH 2/2] ARM: STi: DT: STiH407: Add cpu-release-addr dt property.

[Peter Griffin]

To enable SMP when booting via u-boot we need to specify the
newly implemented cpu-release-addr DT property.

Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
---
 arch/arm/boot/dts/stih407-family.dtsi | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/boot/dts/stih407-family.dtsi b/arch/arm/boot/dts/stih407-family.dtsi
index c06a546..3c90227 100644
--- a/arch/arm/boot/dts/stih407-family.dtsi
+++ b/arch/arm/boot/dts/stih407-family.dtsi
@@ -19,11 +19,15 @@
 			device_type = "cpu";
 			compatible = "arm,cortex-a9";
 			reg = <0>;
+			/* u-boot puts hpen in SBC dmem at 0xa4 offset */
+			cpu-release-addr = <0x94100A4>;
 		};
 		cpu@1 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a9";
 			reg = <1>;
+			/* u-boot puts hpen in SBC dmem at 0xa4 offset */
+			cpu-release-addr = <0x94100A4>;
 		};
 	};
 
-- 
1.9.1

Re: [PATCH 1/2] ARM: STi: Add code to release secondary cores from holding pen.

[Maxime Coquelin]

Hi Peter,

On 06/08/2015 06:16 PM, Peter Griffin wrote:
> Most upstream devs boot STi platform via JTAG which abuses the
> boot process by setting the PC of secondary cores directly. As
> a consquence, booting STi platforms via u-boot results in only
> the primary core being brought up as the code to manage the
> holding pen is not upstream.
>
> This patch adds the necessary code to bring the secondary cores
> out of the holding pen. It uses the cpu-release-addr DT property
> to get the address of the holding pen from the bootloader.
>
> With this patch booting upstream kernels via u-boot works
> correctly:
>
> [    0.045456] CPU: Testing write buffer coherency: ok
> [    0.045597] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
> [    0.045734] Setting up static identity map for 0x40209000 - 0x40209098
> [    0.065047] CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
> [    0.065081] Brought up 2 CPUs
> [    0.065089] SMP: Total of 2 processors activated (5983.43 BogoMIPS).
> [    0.065092] CPU: All CPU(s) started in SVC mode.
>
> Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
> ---
>   arch/arm/mach-sti/headsmp.S |  1 +
>   arch/arm/mach-sti/platsmp.c | 56 ++++++++++++++++++++++++++++++++++++++++++---
>   arch/arm/mach-sti/smp.h     |  2 ++
>   3 files changed, 56 insertions(+), 3 deletions(-)

>
> diff --git a/arch/arm/mach-sti/platsmp.c b/arch/arm/mach-sti/platsmp.c
> index d4b624f..6597ed8 100644
> --- a/arch/arm/mach-sti/platsmp.c
> +++ b/arch/arm/mach-sti/platsmp.c

>   
>   struct smp_operations __initdata sti_smp_ops = {
> @@ -114,3 +163,4 @@ struct smp_operations __initdata sti_smp_ops = {
>   	.smp_secondary_init	= sti_secondary_init,
>   	.smp_boot_secondary	= sti_boot_secondary,
>   };
> +
Please remove trailing line.

Once fixed, you can add:
Acked-by: Maxime Coquelin <maxime.coquelin@st.com>

Thanks!
Maxime

Re: [PATCH 2/2] ARM: STi: DT: STiH407: Add cpu-release-addr dt property.

[Maxime Coquelin]

On 06/08/2015 06:16 PM, Peter Griffin wrote:
> To enable SMP when booting via u-boot we need to specify the
> newly implemented cpu-release-addr DT property.
>
> Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
> ---
>   arch/arm/boot/dts/stih407-family.dtsi | 4 ++++
>   1 file changed, 4 insertions(+)
>
Acked-by: Maxime Coquelin <maxime.coquelin@st.com>

Thanks!
Maxime

Re: [PATCH 0/2] Add code to release secondary cores from holding pen.

[Maxime Coquelin]

Hi Peter,

On 06/08/2015 06:16 PM, Peter Griffin wrote:
> I can't test this on a STiH418 platform, as I don't have one, but a similar
> DT change will be required there as well. I'm not sure if u-boot uses
> the same SBC DMEM offset by default or not.
It should have changed.
Could you also patch STiH418 DT to add cpu-release-addr in CPU 2 & 3 nodes?

Thanks,
Maxime