thermal: broadcom: add Northstar thermal driver

Northstar is a SoC family commonly used in home routers. This commit
adds a driver for checking CPU temperature. As Northstar Plus seems to
also have this IP block this new symbol gets ARCH_BCM_IPROC dependency.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Jon Mason <jon.mason@broadcom.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>

drivers/thermal/Kconfig

@@ -392,6 +392,11 @@ config MTK_THERMAL
 	  Enable this option if you want to have support for thermal management
 	  controller present in Mediatek SoCs
 
+menu "Broadcom thermal drivers"
+depends on ARCH_BCM || COMPILE_TEST
+source "drivers/thermal/broadcom/Kconfig"
+endmenu
+
 menu "Texas Instruments thermal drivers"
 depends on ARCH_HAS_BANDGAP || COMPILE_TEST
 depends on HAS_IOMEM

drivers/thermal/Makefile

@@ -27,6 +27,7 @@ thermal_sys-$(CONFIG_CLOCK_THERMAL)	+= clock_cooling.o
 thermal_sys-$(CONFIG_DEVFREQ_THERMAL) += devfreq_cooling.o
 
 # platform thermal drivers
+obj-y				+= broadcom/
 obj-$(CONFIG_QCOM_SPMI_TEMP_ALARM)	+= qcom-spmi-temp-alarm.o
 obj-$(CONFIG_SPEAR_THERMAL)	+= spear_thermal.o
 obj-$(CONFIG_ROCKCHIP_THERMAL)	+= rockchip_thermal.o

drivers/thermal/broadcom/Kconfig

+config BCM_NS_THERMAL
+	tristate "Northstar thermal driver"
+	depends on ARCH_BCM_IPROC || COMPILE_TEST
+	help
+	  Northstar is a family of SoCs that includes e.g. BCM4708, BCM47081,
+	  BCM4709 and BCM47094. It contains DMU (Device Management Unit) block
+	  with a thermal sensor that allows checking CPU temperature. This
+	  driver provides support for it.

drivers/thermal/broadcom/Makefile

+obj-$(CONFIG_BCM_NS_THERMAL)		+= ns-thermal.o

drivers/thermal/broadcom/ns-thermal.c

+/*
+ * Copyright (C) 2017 Rafał Miłecki <rafal@milecki.pl>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/thermal.h>
+
+#define PVTMON_CONTROL0					0x00
+#define PVTMON_CONTROL0_SEL_MASK			0x0000000e
+#define PVTMON_CONTROL0_SEL_TEMP_MONITOR		0x00000000
+#define PVTMON_CONTROL0_SEL_TEST_MODE			0x0000000e
+#define PVTMON_STATUS					0x08
+
+struct ns_thermal {
+	struct thermal_zone_device *tz;
+	void __iomem *pvtmon;
+};
+
+static int ns_thermal_get_temp(void *data, int *temp)
+{
+	struct ns_thermal *ns_thermal = data;
+	int offset = thermal_zone_get_offset(ns_thermal->tz);
+	int slope = thermal_zone_get_slope(ns_thermal->tz);
+	u32 val;
+
+	val = readl(ns_thermal->pvtmon + PVTMON_CONTROL0);
+	if ((val & PVTMON_CONTROL0_SEL_MASK) != PVTMON_CONTROL0_SEL_TEMP_MONITOR) {
+		/* Clear current mode selection */
+		val &= ~PVTMON_CONTROL0_SEL_MASK;
+
+		/* Set temp monitor mode (it's the default actually) */
+		val |= PVTMON_CONTROL0_SEL_TEMP_MONITOR;
+
+		writel(val, ns_thermal->pvtmon + PVTMON_CONTROL0);
+	}
+
+	val = readl(ns_thermal->pvtmon + PVTMON_STATUS);
+	*temp = slope * val + offset;
+
+	return 0;
+}
+
+static const struct thermal_zone_of_device_ops ns_thermal_ops = {
+	.get_temp = ns_thermal_get_temp,
+};
+
+static int ns_thermal_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct ns_thermal *ns_thermal;
+
+	ns_thermal = devm_kzalloc(dev, sizeof(*ns_thermal), GFP_KERNEL);
+	if (!ns_thermal)
+		return -ENOMEM;
+
+	ns_thermal->pvtmon = of_iomap(dev_of_node(dev), 0);
+	if (WARN_ON(!ns_thermal->pvtmon))
+		return -ENOENT;
+
+	ns_thermal->tz = devm_thermal_zone_of_sensor_register(dev, 0,
+							      ns_thermal,
+							      &ns_thermal_ops);
+	if (IS_ERR(ns_thermal->tz)) {
+		iounmap(ns_thermal->pvtmon);
+		return PTR_ERR(ns_thermal->tz);
+	}
+
+	platform_set_drvdata(pdev, ns_thermal);
+
+	return 0;
+}
+
+static int ns_thermal_remove(struct platform_device *pdev)
+{
+	struct ns_thermal *ns_thermal = platform_get_drvdata(pdev);
+
+	iounmap(ns_thermal->pvtmon);
+
+	return 0;
+}
+
+static const struct of_device_id ns_thermal_of_match[] = {
+	{ .compatible = "brcm,ns-thermal", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, ns_thermal_of_match);
+
+static struct platform_driver ns_thermal_driver = {
+	.probe		= ns_thermal_probe,
+	.remove		= ns_thermal_remove,
+	.driver = {
+		.name = "ns-thermal",
+		.of_match_table = ns_thermal_of_match,
+	},
+};
+module_platform_driver(ns_thermal_driver);
+
+MODULE_DESCRIPTION("Northstar thermal driver");
+MODULE_LICENSE("GPL v2");