5 files changed, 102 insertions, 1 deletions

diff --git a/arch/powerpc/platforms/microwatt/Kconfig b/arch/powerpc/platforms/microwatt/Kconfig
index 6af443a1db99..cb2aff635bb0 100644
--- a/arch/powerpc/platforms/microwatt/Kconfig
+++ b/arch/powerpc/platforms/microwatt/Kconfig
@@ -1,11 +1,12 @@
 # SPDX-License-Identifier: GPL-2.0
 config PPC_MICROWATT
-	depends on PPC_BOOK3S_64 && !SMP
+	depends on PPC_BOOK3S_64
 	bool "Microwatt SoC platform"
 	select PPC_XICS
 	select PPC_ICS_NATIVE
 	select PPC_ICP_NATIVE
 	select PPC_UDBG_16550
+	select COMMON_CLK
 	help
           This option enables support for FPGA-based Microwatt implementations.
 
diff --git a/arch/powerpc/platforms/microwatt/Makefile b/arch/powerpc/platforms/microwatt/Makefile
index 116d6d3ad3f0..d973b2ab4042 100644
--- a/arch/powerpc/platforms/microwatt/Makefile
+++ b/arch/powerpc/platforms/microwatt/Makefile
@@ -1 +1,2 @@
 obj-y	+= setup.o rng.o
+obj-$(CONFIG_SMP) += smp.o
diff --git a/arch/powerpc/platforms/microwatt/microwatt.h b/arch/powerpc/platforms/microwatt/microwatt.h
index 335417e95e66..891aa2800768 100644
--- a/arch/powerpc/platforms/microwatt/microwatt.h
+++ b/arch/powerpc/platforms/microwatt/microwatt.h
@@ -3,5 +3,6 @@
 #define _MICROWATT_H
 
 void microwatt_rng_init(void);
+void microwatt_init_smp(void);
 
 #endif /* _MICROWATT_H */
diff --git a/arch/powerpc/platforms/microwatt/setup.c b/arch/powerpc/platforms/microwatt/setup.c
index 5e1c0997170d..6af2ccef736c 100644
--- a/arch/powerpc/platforms/microwatt/setup.c
+++ b/arch/powerpc/platforms/microwatt/setup.c
@@ -29,15 +29,33 @@ static int __init microwatt_populate(void)
 }
 machine_arch_initcall(microwatt, microwatt_populate);
 
+static int __init microwatt_probe(void)
+{
+	/* Main reason for having this is to start the other CPU(s) */
+	if (IS_ENABLED(CONFIG_SMP))
+		microwatt_init_smp();
+	return 1;
+}
+
 static void __init microwatt_setup_arch(void)
 {
 	microwatt_rng_init();
 }
 
+static void microwatt_idle(void)
+{
+	if (!prep_irq_for_idle_irqsoff())
+		return;
+
+	__asm__ __volatile__ ("wait");
+}
+
 define_machine(microwatt) {
 	.name			= "microwatt",
 	.compatible		= "microwatt-soc",
+	.probe			= microwatt_probe,
 	.init_IRQ		= microwatt_init_IRQ,
 	.setup_arch		= microwatt_setup_arch,
 	.progress		= udbg_progress,
+	.power_save		= microwatt_idle,
 };
diff --git a/arch/powerpc/platforms/microwatt/smp.c b/arch/powerpc/platforms/microwatt/smp.c
new file mode 100644
index 000000000000..7dbf2ca73d47
--- /dev/null
+++ b/arch/powerpc/platforms/microwatt/smp.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/*
+ * SMP support functions for Microwatt
+ * Copyright 2025 Paul Mackerras <paulus@ozlabs.org>
+ */
+
+#include <linux/kernel.h>
+#include <linux/smp.h>
+#include <linux/io.h>
+#include <asm/early_ioremap.h>
+#include <asm/ppc-opcode.h>
+#include <asm/reg.h>
+#include <asm/smp.h>
+#include <asm/xics.h>
+
+#include "microwatt.h"
+
+static void __init microwatt_smp_probe(void)
+{
+	xics_smp_probe();
+}
+
+static void microwatt_smp_setup_cpu(int cpu)
+{
+	if (cpu != 0)
+		xics_setup_cpu();
+}
+
+static struct smp_ops_t microwatt_smp_ops = {
+	.probe		= microwatt_smp_probe,
+	.message_pass	= NULL,		/* Use smp_muxed_ipi_message_pass */
+	.kick_cpu	= smp_generic_kick_cpu,
+	.setup_cpu	= microwatt_smp_setup_cpu,
+};
+
+/* XXX get from device tree */
+#define SYSCON_BASE	0xc0000000
+#define SYSCON_LENGTH	0x100
+
+#define SYSCON_CPU_CTRL	0x58
+
+void __init microwatt_init_smp(void)
+{
+	volatile unsigned char __iomem *syscon;
+	int ncpus;
+	int timeout;
+
+	syscon = early_ioremap(SYSCON_BASE, SYSCON_LENGTH);
+	if (syscon == NULL) {
+		pr_err("Failed to map SYSCON\n");
+		return;
+	}
+	ncpus = (readl(syscon + SYSCON_CPU_CTRL) >> 8) & 0xff;
+	if (ncpus < 2)
+		goto out;
+
+	smp_ops = &microwatt_smp_ops;
+
+	/*
+	 * Write two instructions at location 0:
+	 * mfspr r3, PIR
+	 * b __secondary_hold
+	 */
+	*(unsigned int *)KERNELBASE = PPC_RAW_MFSPR(3, SPRN_PIR);
+	*(unsigned int *)(KERNELBASE+4) = PPC_RAW_BRANCH(&__secondary_hold - (char *)(KERNELBASE+4));
+
+	/* enable the other CPUs, they start at location 0 */
+	writel((1ul << ncpus) - 1, syscon + SYSCON_CPU_CTRL);
+
+	timeout = 10000;
+	while (!__secondary_hold_acknowledge) {
+		if (--timeout == 0)
+			break;
+		barrier();
+	}
+
+ out:
+	early_iounmap((void *)syscon, SYSCON_LENGTH);
+}