Add cpuhotplug support for Exynos850 platforms. This SoC requires
its own specific set of writes/updates to PMU and PMU interrupts
generation block in order to put a CPU or a group of CPUs into
a different sleep states or prepare these entities for a CPU_OFF
or wake-up out of idle state or after CPU online.
Without these writes/updates the CPU(s) wake-up or online fails.
While at this, also add description of Exynos850 PMU registers.

Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
---
 drivers/soc/samsung/Makefile                |  2 +-
 drivers/soc/samsung/exynos-pmu.c            |  1 +
 drivers/soc/samsung/exynos-pmu.h            |  1 +
 drivers/soc/samsung/exynos850-pmu.c         | 78 +++++++++++++++++++++++++++++
 include/linux/soc/samsung/exynos-regs-pmu.h |  5 ++
 5 files changed, 86 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/samsung/Makefile b/drivers/soc/samsung/Makefile
index 636a762608c9..7f544e3c1fcc 100644
--- a/drivers/soc/samsung/Makefile
+++ b/drivers/soc/samsung/Makefile
@@ -7,7 +7,7 @@ exynos_chipid-y			+= exynos-chipid.o exynos-asv.o
 obj-$(CONFIG_EXYNOS_USI)	+= exynos-usi.o
 
 obj-$(CONFIG_EXYNOS_PMU)	+= exynos_pmu.o
-exynos_pmu-y			+= exynos-pmu.o gs101-pmu.o
+exynos_pmu-y			+= exynos-pmu.o gs101-pmu.o exynos850-pmu.o
 
 obj-$(CONFIG_EXYNOS_PMU_ARM_DRIVERS)	+= exynos3250-pmu.o exynos4-pmu.o \
 					exynos5250-pmu.o exynos5420-pmu.o
diff --git a/drivers/soc/samsung/exynos-pmu.c b/drivers/soc/samsung/exynos-pmu.c
index 4e5fcc01e5e0..daa870ba88f5 100644
--- a/drivers/soc/samsung/exynos-pmu.c
+++ b/drivers/soc/samsung/exynos-pmu.c
@@ -133,6 +133,7 @@ static const struct of_device_id exynos_pmu_of_device_ids[] = {
 		.compatible = "samsung,exynos7-pmu",
 	}, {
 		.compatible = "samsung,exynos850-pmu",
+		.data = &exynos850_pmu_data,
 	},
 	{ /*sentinel*/ },
 };
diff --git a/drivers/soc/samsung/exynos-pmu.h b/drivers/soc/samsung/exynos-pmu.h
index 186299a049a8..4202d3cd94c9 100644
--- a/drivers/soc/samsung/exynos-pmu.h
+++ b/drivers/soc/samsung/exynos-pmu.h
@@ -102,6 +102,7 @@ extern const struct exynos_pmu_data exynos5250_pmu_data;
 extern const struct exynos_pmu_data exynos5420_pmu_data;
 #endif
 extern const struct exynos_pmu_data gs101_pmu_data;
+extern const struct exynos_pmu_data exynos850_pmu_data;
 
 extern void pmu_raw_writel(u32 val, u32 offset);
 extern u32 pmu_raw_readl(u32 offset);
diff --git a/drivers/soc/samsung/exynos850-pmu.c b/drivers/soc/samsung/exynos850-pmu.c
new file mode 100644
index 000000000000..b3841547577a
--- /dev/null
+++ b/drivers/soc/samsung/exynos850-pmu.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2026 Linaro Ltd.
+ *
+ * Exynos850 PMU support
+ */
+
+#include <linux/soc/samsung/exynos-pmu.h>
+#include <linux/soc/samsung/exynos-regs-pmu.h>
+#include <linux/regmap.h>
+
+#include "exynos-pmu.h"
+
+static int exynos850_cpu_pmu_offline(struct exynos_pmu_context *pmu_context, unsigned int cpu)
+	__must_hold(&pmu_context->cpupm_lock)
+{
+	u32 this_cluster = MPIDR_AFFINITY_LEVEL(read_cpuid_mpidr(), 2);
+	u32 cluster_cpu = MPIDR_AFFINITY_LEVEL(read_cpuid_mpidr(), 1);
+	unsigned int cpuhint = smp_processor_id();
+	u32 reg, mask;
+
+	/* set cpu inform hint */
+	regmap_write(pmu_context->pmureg, EXYNOS850_CPU_INFORM(cpuhint),
+		     CPU_INFORM_C2);
+
+	mask = BIT(cpu);
+	regmap_update_bits(pmu_context->pmuintrgen, EXYNOS_GRP2_INTR_BID_ENABLE,
+			   mask, BIT(cpu));
+
+	regmap_read(pmu_context->pmuintrgen, EXYNOS_GRP1_INTR_BID_UPEND, &reg);
+	regmap_write(pmu_context->pmuintrgen, EXYNOS_GRP1_INTR_BID_CLEAR,
+		     reg & mask);
+
+	mask = (BIT(cpu + 8));
+	regmap_read(pmu_context->pmuintrgen, EXYNOS_GRP1_INTR_BID_UPEND, &reg);
+	regmap_write(pmu_context->pmuintrgen, EXYNOS_GRP1_INTR_BID_CLEAR,
+		     reg & mask);
+
+	regmap_update_bits(pmu_context->pmureg,
+			   EXYNOS850_CLUSTER_CPU_INT_EN(this_cluster, cluster_cpu),
+			   1 << 3, 1 << 3);
+	return 0;
+}
+
+static int exynos850_cpu_pmu_online(struct exynos_pmu_context *pmu_context, unsigned int cpu)
+	__must_hold(&pmu_context->cpupm_lock)
+{
+	u32 this_cluster = MPIDR_AFFINITY_LEVEL(read_cpuid_mpidr(), 2);
+	u32 cluster_cpu = MPIDR_AFFINITY_LEVEL(read_cpuid_mpidr(), 1);
+	unsigned int cpuhint = smp_processor_id();
+	u32 reg, mask;
+
+	/* clear cpu inform hint */
+	regmap_write(pmu_context->pmureg, EXYNOS850_CPU_INFORM(cpuhint),
+		     CPU_INFORM_CLEAR);
+
+	mask = BIT(cpu);
+
+	regmap_update_bits(pmu_context->pmuintrgen, EXYNOS_GRP2_INTR_BID_ENABLE,
+			   mask, (0 << cpu));
+
+	regmap_read(pmu_context->pmuintrgen, EXYNOS_GRP2_INTR_BID_UPEND, &reg);
+
+	regmap_write(pmu_context->pmuintrgen, EXYNOS_GRP2_INTR_BID_CLEAR,
+		     reg & mask);
+
+	regmap_update_bits(pmu_context->pmureg,
+			   EXYNOS850_CLUSTER_CPU_INT_EN(this_cluster, cluster_cpu),
+			   1 << 3, 0 << 3);
+	return 0;
+}
+
+const struct exynos_pmu_data exynos850_pmu_data = {
+	.pmu_cpuhp = true,
+	.cpu_pmu_offline = exynos850_cpu_pmu_offline,
+	.cpu_pmu_online = exynos850_cpu_pmu_online,
+};
+
diff --git a/include/linux/soc/samsung/exynos-regs-pmu.h b/include/linux/soc/samsung/exynos-regs-pmu.h
index 9c4d3da41dbf..93c4d724c8ea 100644
--- a/include/linux/soc/samsung/exynos-regs-pmu.h
+++ b/include/linux/soc/samsung/exynos-regs-pmu.h
@@ -1015,6 +1015,11 @@
 #define EXYNOS_GRP2_INTR_BID_UPEND				(0x0208)
 #define EXYNOS_GRP2_INTR_BID_CLEAR				(0x020c)
 
+/* Exynos850 PMU Alive */
+#define EXYNOS850_CPU_INFORM(cpu)		(0x0860 + ((cpu) & 7) * 4)
+#define EXYNOS850_CLUSTER_CPU_OFFSET(cl, cpu)	(0x1000 + ((cl * 0x400) + ((cpu) * 0x80)))
+#define EXYNOS850_CLUSTER_CPU_INT_EN(cl, cpu)	(EXYNOS850_CLUSTER_CPU_OFFSET(cl, cpu) + 0x44)
+
 /* exynosautov920 */
 #define EXYNOSAUTOV920_PHY_CTRL_USB20				(0x0710)
 #define EXYNOSAUTOV920_PHY_CTRL_USB31				(0x0714)

-- 
2.51.0