thermal: imx_sc: add i.MX system controller thermal support

i.MX8QXP is an ARMv8 SoC which has a Cortex-M4 system controller
inside, the system controller is in charge of controlling power,
clock and thermal sensors etc..

This patch adds i.MX system controller thermal driver support,
Linux kernel has to communicate with system controller via MU
(message unit) IPC to get each thermal sensor's temperature,
it supports multiple sensors which are passed from device tree,
please see the binding doc for details.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/1582330132-13461-3-git-send-email-Anson.Huang@nxp.com

drivers/thermal/Kconfig

@@ -251,6 +251,17 @@ config IMX_THERMAL
 	  cpufreq is used as the cooling device to throttle CPUs when the
 	  passive trip is crossed.
 
+config IMX_SC_THERMAL
+	tristate "Temperature sensor driver for NXP i.MX SoCs with System Controller"
+	depends on IMX_SCU || COMPILE_TEST
+	depends on OF
+	help
+	  Support for Temperature Monitor (TEMPMON) found on NXP i.MX SoCs with
+	  system controller inside, Linux kernel has to communicate with system
+	  controller via MU (message unit) IPC to get temperature from thermal
+	  sensor. It supports one critical trip point and one
+	  passive trip point for each thermal sensor.
+
 config MAX77620_THERMAL
 	tristate "Temperature sensor driver for Maxim MAX77620 PMIC"
 	depends on MFD_MAX77620

drivers/thermal/Makefile

@@ -43,6 +43,7 @@ obj-$(CONFIG_DB8500_THERMAL)	+= db8500_thermal.o
 obj-$(CONFIG_ARMADA_THERMAL)	+= armada_thermal.o
 obj-$(CONFIG_TANGO_THERMAL)	+= tango_thermal.o
 obj-$(CONFIG_IMX_THERMAL)	+= imx_thermal.o
+obj-$(CONFIG_IMX_SC_THERMAL)	+= imx_sc_thermal.o
 obj-$(CONFIG_MAX77620_THERMAL)	+= max77620_thermal.o
 obj-$(CONFIG_QORIQ_THERMAL)	+= qoriq_thermal.o
 obj-$(CONFIG_DA9062_THERMAL)	+= da9062-thermal.o

drivers/thermal/imx_sc_thermal.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2018-2020 NXP.
+ */
+
+#include <linux/err.h>
+#include <linux/firmware/imx/sci.h>
+#include <linux/firmware/imx/types.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/thermal.h>
+
+#include "thermal_core.h"
+
+#define IMX_SC_MISC_FUNC_GET_TEMP	13
+
+static struct imx_sc_ipc *thermal_ipc_handle;
+
+struct imx_sc_sensor {
+	struct thermal_zone_device *tzd;
+	u32 resource_id;
+};
+
+struct req_get_temp {
+	u16 resource_id;
+	u8 type;
+} __packed;
+
+struct resp_get_temp {
+	u16 celsius;
+	u8 tenths;
+} __packed;
+
+struct imx_sc_msg_misc_get_temp {
+	struct imx_sc_rpc_msg hdr;
+	union {
+		struct req_get_temp req;
+		struct resp_get_temp resp;
+	} data;
+};
+
+static int imx_sc_thermal_get_temp(void *data, int *temp)
+{
+	struct imx_sc_msg_misc_get_temp msg;
+	struct imx_sc_rpc_msg *hdr = &msg.hdr;
+	struct imx_sc_sensor *sensor = data;
+	int ret;
+
+	msg.data.req.resource_id = sensor->resource_id;
+	msg.data.req.type = IMX_SC_C_TEMP;
+
+	hdr->ver = IMX_SC_RPC_VERSION;
+	hdr->svc = IMX_SC_RPC_SVC_MISC;
+	hdr->func = IMX_SC_MISC_FUNC_GET_TEMP;
+	hdr->size = 2;
+
+	ret = imx_scu_call_rpc(thermal_ipc_handle, &msg, true);
+	if (ret) {
+		dev_err(&sensor->tzd->device, "read temp sensor %d failed, ret %d\n",
+			sensor->resource_id, ret);
+		return ret;
+	}
+
+	*temp = msg.data.resp.celsius * 1000 + msg.data.resp.tenths * 100;
+
+	return 0;
+}
+
+static const struct thermal_zone_of_device_ops imx_sc_thermal_ops = {
+	.get_temp = imx_sc_thermal_get_temp,
+};
+
+static int imx_sc_thermal_probe(struct platform_device *pdev)
+{
+	struct device_node *np, *child, *sensor_np;
+	struct imx_sc_sensor *sensor;
+	int ret;
+
+	ret = imx_scu_get_handle(&thermal_ipc_handle);
+	if (ret)
+		return ret;
+
+	np = of_find_node_by_name(NULL, "thermal-zones");
+	if (!np)
+		return -ENODEV;
+
+	sensor_np = of_node_get(pdev->dev.of_node);
+
+	for_each_available_child_of_node(np, child) {
+		sensor = devm_kzalloc(&pdev->dev, sizeof(*sensor), GFP_KERNEL);
+		if (!sensor) {
+			of_node_put(sensor_np);
+			return -ENOMEM;
+		}
+
+		ret = thermal_zone_of_get_sensor_id(child,
+						    sensor_np,
+						    &sensor->resource_id);
+		if (ret < 0) {
+			dev_err(&pdev->dev,
+				"failed to get valid sensor resource id: %d\n",
+				ret);
+			break;
+		}
+
+		sensor->tzd = devm_thermal_zone_of_sensor_register(&pdev->dev,
+								   sensor->resource_id,
+								   sensor,
+								   &imx_sc_thermal_ops);
+		if (IS_ERR(sensor->tzd)) {
+			dev_err(&pdev->dev, "failed to register thermal zone\n");
+			ret = PTR_ERR(sensor->tzd);
+			break;
+		}
+	}
+
+	of_node_put(sensor_np);
+
+	return ret;
+}
+
+static int imx_sc_thermal_remove(struct platform_device *pdev)
+{
+	return 0;
+}
+
+static const struct of_device_id imx_sc_thermal_table[] = {
+	{ .compatible = "fsl,imx-sc-thermal", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, imx_sc_thermal_table);
+
+static struct platform_driver imx_sc_thermal_driver = {
+		.probe = imx_sc_thermal_probe,
+		.remove	= imx_sc_thermal_remove,
+		.driver = {
+			.name = "imx-sc-thermal",
+			.of_match_table = imx_sc_thermal_table,
+		},
+};
+module_platform_driver(imx_sc_thermal_driver);
+
+MODULE_AUTHOR("Anson Huang <Anson.Huang@nxp.com>");
+MODULE_DESCRIPTION("Thermal driver for NXP i.MX SoCs with system controller");
+MODULE_LICENSE("GPL v2");