firmware: imx: Add i.MX95 SCMI CPU driver

The i.MX95 System manager exports SCMI CPU protocol for linux to manage
cpu cores. The driver is to use the cpu Protocol interface to
start, stop a cpu cores (eg, M7).

Reviewed-by: Cristian Marussi <[e-mail]>
Signed-off-by: Peng Fan <[e-mail]>
Message-Id: <[e-mail]>
Signed-off-by: Sudeep Holla <[e-mail]>

drivers/firmware/arm_scmi/vendors/imx/Kconfig

···
 config IMX_SCMI_CPU_EXT
 	tristate "i.MX SCMI CPU EXTENSION"
 	depends on ARM_SCMI_PROTOCOL || (COMPILE_TEST && OF)
+	depends on IMX_SCMI_CPU_DRV
 	default y if ARCH_MXC
 	help
 	  This enables i.MX System CPU Protocol to manage cpu

drivers/firmware/imx/Kconfig

···
 	  This driver manages the IPC interface between host CPU and the
 	  SCU firmware running on M4.
 
+config IMX_SCMI_CPU_DRV
+	tristate "IMX SCMI CPU Protocol driver"
+	depends on ARCH_MXC || COMPILE_TEST
+	default y if ARCH_MXC
+	help
+	  The System Controller Management Interface firmware (SCMI FW) is
+	  a low-level system function which runs on a dedicated Cortex-M
+	  core that could provide cpu management features.
+
+	  This driver can also be built as a module.
+
 config IMX_SCMI_LMM_DRV
 	tristate "IMX SCMI LMM Protocol driver"
 	depends on ARCH_MXC || COMPILE_TEST

drivers/firmware/imx/Makefile

···
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_IMX_DSP)		+= imx-dsp.o
 obj-$(CONFIG_IMX_SCU)		+= imx-scu.o misc.o imx-scu-irq.o rm.o imx-scu-soc.o
+obj-${CONFIG_IMX_SCMI_CPU_DRV}	+= sm-cpu.o
 obj-${CONFIG_IMX_SCMI_MISC_DRV}	+= sm-misc.o
 obj-${CONFIG_IMX_SCMI_LMM_DRV}	+= sm-lmm.o

drivers/firmware/imx/sm-cpu.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2025 NXP
+ */
+
+#include <linux/firmware/imx/sm.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/scmi_protocol.h>
+#include <linux/scmi_imx_protocol.h>
+
+static const struct scmi_imx_cpu_proto_ops *imx_cpu_ops;
+static struct scmi_protocol_handle *ph;
+
+int scmi_imx_cpu_reset_vector_set(u32 cpuid, u64 vector, bool start, bool boot,
+				  bool resume)
+{
+	if (!ph)
+		return -EPROBE_DEFER;
+
+	return imx_cpu_ops->cpu_reset_vector_set(ph, cpuid, vector, start,
+						 boot, resume);
+}
+EXPORT_SYMBOL(scmi_imx_cpu_reset_vector_set);
+
+int scmi_imx_cpu_start(u32 cpuid, bool start)
+{
+	if (!ph)
+		return -EPROBE_DEFER;
+
+	if (start)
+		return imx_cpu_ops->cpu_start(ph, cpuid, true);
+
+	return imx_cpu_ops->cpu_start(ph, cpuid, false);
+};
+EXPORT_SYMBOL(scmi_imx_cpu_start);
+
+int scmi_imx_cpu_started(u32 cpuid, bool *started)
+{
+	if (!ph)
+		return -EPROBE_DEFER;
+
+	if (!started)
+		return -EINVAL;
+
+	return imx_cpu_ops->cpu_started(ph, cpuid, started);
+};
+EXPORT_SYMBOL(scmi_imx_cpu_started);
+
+static int scmi_imx_cpu_probe(struct scmi_device *sdev)
+{
+	const struct scmi_handle *handle = sdev->handle;
+
+	if (!handle)
+		return -ENODEV;
+
+	if (imx_cpu_ops) {
+		dev_err(&sdev->dev, "sm cpu already initialized\n");
+		return -EEXIST;
+	}
+
+	imx_cpu_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_IMX_CPU, &ph);
+	if (IS_ERR(imx_cpu_ops))
+		return PTR_ERR(imx_cpu_ops);
+
+	return 0;
+}
+
+static const struct scmi_device_id scmi_id_table[] = {
+	{ SCMI_PROTOCOL_IMX_CPU, "imx-cpu" },
+	{ },
+};
+MODULE_DEVICE_TABLE(scmi, scmi_id_table);
+
+static struct scmi_driver scmi_imx_cpu_driver = {
+	.name = "scmi-imx-cpu",
+	.probe = scmi_imx_cpu_probe,
+	.id_table = scmi_id_table,
+};
+module_scmi_driver(scmi_imx_cpu_driver);
+
+MODULE_AUTHOR("Peng Fan <[e-mail]>");
+MODULE_DESCRIPTION("IMX SM CPU driver");
+MODULE_LICENSE("GPL");

include/linux/firmware/imx/sm.h

···
 int scmi_imx_misc_ctrl_get(u32 id, u32 *num, u32 *val);
 int scmi_imx_misc_ctrl_set(u32 id, u32 val);
 
+int scmi_imx_cpu_start(u32 cpuid, bool start);
+int scmi_imx_cpu_started(u32 cpuid, bool *started);
+int scmi_imx_cpu_reset_vector_set(u32 cpuid, u64 vector, bool start, bool boot,
+				  bool resume);
+
 enum scmi_imx_lmm_op {
 	SCMI_IMX_LMM_BOOT,
 	SCMI_IMX_LMM_POWER_ON,