thermal: imx8mm: Add support for i.MX8MM thermal monitoring unit

i.MX8MM has a thermal monitoring unit(TMU) inside, it ONLY has one
sensor for CPU, add support for reading immediate temperature of
this sensor.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/1582947862-11073-2-git-send-email-Anson.Huang@nxp.com

drivers/thermal/Kconfig

@@ -262,6 +262,16 @@ config IMX_SC_THERMAL
 	  sensor. It supports one critical trip point and one
 	  passive trip point for each thermal sensor.
 
+config IMX8MM_THERMAL
+	tristate "Temperature sensor driver for Freescale i.MX8MM SoC"
+	depends on ARCH_MXC
+	depends on OF
+	help
+	  Support for Thermal Monitoring Unit (TMU) found on Freescale i.MX8MM SoC.
+	  It supports one critical trip point and one passive trip point. The
+	  cpufreq is used as the cooling device to throttle CPUs when the passive
+	  trip is crossed.
+
 config MAX77620_THERMAL
 	tristate "Temperature sensor driver for Maxim MAX77620 PMIC"
 	depends on MFD_MAX77620

drivers/thermal/Makefile

@@ -44,6 +44,7 @@ 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-$(CONFIG_IMX8MM_THERMAL)	+= imx8mm_thermal.o
 obj-$(CONFIG_MAX77620_THERMAL)	+= max77620_thermal.o
 obj-$(CONFIG_QORIQ_THERMAL)	+= qoriq_thermal.o
 obj-$(CONFIG_DA9062_THERMAL)	+= da9062-thermal.o

drivers/thermal/imx8mm_thermal.c

@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2020 NXP.
+ *
+ * Author: Anson Huang <Anson.Huang@nxp.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/thermal.h>
+
+#include "thermal_core.h"
+
+#define TER			0x0	/* TMU enable */
+#define TRITSR			0x20	/* TMU immediate temp */
+
+#define TER_EN			BIT(31)
+#define TRITSR_VAL_MASK		0xff
+
+#define TEMP_LOW_LIMIT		10
+
+struct imx8mm_tmu {
+	struct thermal_zone_device *tzd;
+	void __iomem *base;
+	struct clk *clk;
+};
+
+static int tmu_get_temp(void *data, int *temp)
+{
+	struct imx8mm_tmu *tmu = data;
+	u32 val;
+
+	val = readl_relaxed(tmu->base + TRITSR) & TRITSR_VAL_MASK;
+	if (val < TEMP_LOW_LIMIT)
+		return -EAGAIN;
+
+	*temp = val * 1000;
+
+	return 0;
+}
+
+static struct thermal_zone_of_device_ops tmu_tz_ops = {
+	.get_temp = tmu_get_temp,
+};
+
+static int imx8mm_tmu_probe(struct platform_device *pdev)
+{
+	struct imx8mm_tmu *tmu;
+	u32 val;
+	int ret;
+
+	tmu = devm_kzalloc(&pdev->dev, sizeof(struct imx8mm_tmu), GFP_KERNEL);
+	if (!tmu)
+		return -ENOMEM;
+
+	tmu->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(tmu->base))
+		return PTR_ERR(tmu->base);
+
+	tmu->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(tmu->clk)) {
+		ret = PTR_ERR(tmu->clk);
+		if (ret != -EPROBE_DEFER)
+			dev_err(&pdev->dev,
+				"failed to get tmu clock: %d\n", ret);
+		return ret;
+	}
+
+	ret = clk_prepare_enable(tmu->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to enable tmu clock: %d\n", ret);
+		return ret;
+	}
+
+	tmu->tzd = devm_thermal_zone_of_sensor_register(&pdev->dev, 0,
+							tmu, &tmu_tz_ops);
+	if (IS_ERR(tmu->tzd)) {
+		dev_err(&pdev->dev,
+			"failed to register thermal zone sensor: %d\n", ret);
+		return PTR_ERR(tmu->tzd);
+	}
+
+	platform_set_drvdata(pdev, tmu);
+
+	/* enable the monitor */
+	val = readl_relaxed(tmu->base + TER);
+	val |= TER_EN;
+	writel_relaxed(val, tmu->base + TER);
+
+	return 0;
+}
+
+static int imx8mm_tmu_remove(struct platform_device *pdev)
+{
+	struct imx8mm_tmu *tmu = platform_get_drvdata(pdev);
+	u32 val;
+
+	/* disable TMU */
+	val = readl_relaxed(tmu->base + TER);
+	val &= ~TER_EN;
+	writel_relaxed(val, tmu->base + TER);
+
+	clk_disable_unprepare(tmu->clk);
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+
+static const struct of_device_id imx8mm_tmu_table[] = {
+	{ .compatible = "fsl,imx8mm-tmu", },
+	{ },
+};
+
+static struct platform_driver imx8mm_tmu = {
+	.driver = {
+		.name	= "i.mx8mm_thermal",
+		.of_match_table = imx8mm_tmu_table,
+	},
+	.probe = imx8mm_tmu_probe,
+	.remove = imx8mm_tmu_remove,
+};
+module_platform_driver(imx8mm_tmu);
+
+MODULE_AUTHOR("Anson Huang <Anson.Huang@nxp.com>");
+MODULE_DESCRIPTION("i.MX8MM Thermal Monitor Unit driver");
+MODULE_LICENSE("GPL v2");