[v2,10/10] ARM: mstar: SMP support

Commit Message

Daniel Palmer Dec. 1, 2020, 1:43 p.m. UTC

This patch adds SMP support for MStar/Sigmastar chips that have a second core
like those in the infinity2m family.

So far only single and dual core chips have been found so this does
the bare minimum to boot the second core. From what I can tell not having
the "holding pen" code to handle multiple cores is fine if there is only
one core the will get booted. This might need to be reconsidered if chips
with more cores turn up.

Signed-off-by: Daniel Palmer <[e-mail]>
---
 arch/arm/mach-mstar/mstarv7.c | 48 +++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

Comments

Russell King (Oracle) Dec. 1, 2020, 3:04 p.m. UTC | #1

On Tue, Dec 01, 2020 at 10:43:30PM +0900, Daniel Palmer wrote:
> +	np = of_find_compatible_node(NULL, NULL, "mstar,smpctrl");
> +	smpctrl = of_iomap(np, 0);
> +
> +	if (!smpctrl)
> +		return -ENODEV;

Wouldn't -ENOMEM be more appropriate here?

Daniel Palmer Dec. 2, 2020, 9:10 a.m. UTC | #2

Hi Russell,

On Wed, 2 Dec 2020 at 00:04, Russell King - ARM Linux admin
<[e-mail]> wrote:
>
> On Tue, Dec 01, 2020 at 10:43:30PM +0900, Daniel Palmer wrote:
> > +     np = of_find_compatible_node(NULL, NULL, "mstar,smpctrl");
> > +     smpctrl = of_iomap(np, 0);
> > +
> > +     if (!smpctrl)
> > +             return -ENODEV;
>
> Wouldn't -ENOMEM be more appropriate here?

There seems to be examples of both -ENOMEM and -ENODEV in other ARM platforms.
arch/arm/mach-aspeed/platsmp.c uses -ENODEV for example.

I went with -ENODEV there as the source of the error is most likely
the node not being in the device tree.
I didn't check the result of of_find_compatible_node() because for the
memory barrier code in the same file I was told it wasn't necessary.

Thanks,

Daniel

Patch

diff --git a/arch/arm/mach-mstar/mstarv7.c b/arch/arm/mach-mstar/mstarv7.c
index 1aa748fa006e..274c4f0df270 100644
--- a/arch/arm/mach-mstar/mstarv7.c
+++ b/arch/arm/mach-mstar/mstarv7.c
@@ -31,6 +31,13 @@ 
 #define MSTARV7_L3BRIDGE_FLUSH_TRIGGER	BIT(0)
 #define MSTARV7_L3BRIDGE_STATUS_DONE	BIT(12)
 
+#ifdef CONFIG_SMP
+#define MSTARV7_CPU1_BOOT_ADDR_HIGH	0x4c
+#define MSTARV7_CPU1_BOOT_ADDR_LOW	0x50
+#define MSTARV7_CPU1_UNLOCK		0x58
+#define MSTARV7_CPU1_UNLOCK_MAGIC	0xbabe
+#endif
+
 static void __iomem *l3bridge;
 
 static const char * const mstarv7_board_dt_compat[] __initconst = {
@@ -63,6 +70,46 @@  static void mstarv7_mb(void)
 	}
 }
 
+#ifdef CONFIG_SMP
+static int mstarv7_boot_secondary(unsigned int cpu, struct task_struct *idle)
+{
+	struct device_node *np;
+	u32 bootaddr = (u32) __pa_symbol(secondary_startup_arm);
+	void __iomem *smpctrl;
+
+	/*
+	 * right now we don't know how to boot anything except
+	 * cpu 1.
+	 */
+	if (cpu != 1)
+		return -EINVAL;
+
+	np = of_find_compatible_node(NULL, NULL, "mstar,smpctrl");
+	smpctrl = of_iomap(np, 0);
+
+	if (!smpctrl)
+		return -ENODEV;
+
+	/* set the boot address for the second cpu */
+	writew(bootaddr & 0xffff, smpctrl + MSTARV7_CPU1_BOOT_ADDR_LOW);
+	writew((bootaddr >> 16) & 0xffff, smpctrl + MSTARV7_CPU1_BOOT_ADDR_HIGH);
+
+	/* unlock the second cpu */
+	writew(MSTARV7_CPU1_UNLOCK_MAGIC, smpctrl + MSTARV7_CPU1_UNLOCK);
+
+	/* and away we go...*/
+	arch_send_wakeup_ipi_mask(cpumask_of(cpu));
+
+	iounmap(smpctrl);
+
+	return 0;
+}
+
+static const struct smp_operations __initdata mstarv7_smp_ops = {
+	.smp_boot_secondary = mstarv7_boot_secondary,
+};
+#endif
+
 static void __init mstarv7_init(void)
 {
 	struct device_node *np;
@@ -78,4 +125,5 @@  static void __init mstarv7_init(void)
 DT_MACHINE_START(MSTARV7_DT, "MStar/Sigmastar Armv7 (Device Tree)")
 	.dt_compat	= mstarv7_board_dt_compat,
 	.init_machine	= mstarv7_init,
+	.smp		= smp_ops(mstarv7_smp_ops),
 MACHINE_END