[v8,3/3] thermal: zx2967: add thermal driver for ZTE's zx2967 family

diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index 18f2de6..f64bd50 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -444,4 +444,12 @@  config BCM2835_THERMAL
 	help
 	  Support for thermal sensors on Broadcom bcm2835 SoCs.
 
+config ZX2967_THERMAL
+	tristate "Thermal sensors on zx2967 SoC"
+	depends on ARCH_ZX || COMPILE_TEST
+	help
+	  Enable the zx2967 thermal sensors driver, which supports
+	  the primitive temperature sensor embedded in zx2967 SoCs.
+	  This sensor generates the real time die temperature.
+
 endif
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index 677c6d9..c00c05e 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -57,3 +57,4 @@  obj-$(CONFIG_HISI_THERMAL)     += hisi_thermal.o
 obj-$(CONFIG_MTK_THERMAL)	+= mtk_thermal.o
 obj-$(CONFIG_GENERIC_ADC_THERMAL)	+= thermal-generic-adc.o
 obj-$(CONFIG_BCM2835_THERMAL)	+= bcm2835_thermal.o
+obj-$(CONFIG_ZX2967_THERMAL)	+= zx2967_thermal.o
diff --git a/drivers/thermal/zx2967_thermal.c b/drivers/thermal/zx2967_thermal.c
new file mode 100644
index 0000000..d177238
--- /dev/null
+++ b/drivers/thermal/zx2967_thermal.c
@@ -0,0 +1,255 @@ 
+/*
+ * ZTE's zx2967 family thermal sensor driver
+ *
+ * Copyright (C) 2017 ZTE Ltd.
+ *
+ * Author: Baoyou Xie <baoyou.xie@linaro.org>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/thermal.h>
+
+/* Power Mode: 0->low 1->high */
+#define ZX2967_THERMAL_POWER_MODE	0
+#define ZX2967_POWER_MODE_LOW		0
+#define ZX2967_POWER_MODE_HIGH		1
+
+/* DCF Control Register */
+#define ZX2967_THERMAL_DCF		0x4
+#define ZX2967_DCF_EN			BIT(1)
+#define ZX2967_DCF_FREEZE		BIT(0)
+
+/* Selection Register */
+#define ZX2967_THERMAL_SEL		0x8
+
+/* Control Register */
+#define ZX2967_THERMAL_CTRL		0x10
+
+#define ZX2967_THERMAL_READY		BIT(12)
+#define ZX2967_THERMAL_TEMP_MASK	GENMASK(11, 0)
+#define ZX2967_THERMAL_ID_MASK		0x18
+#define ZX2967_THERMAL_ID		0x10
+
+#define ZX2967_GET_TEMP_TIMEOUT_US	(100 * 1024)
+
+/* zx2967 Thermal Sensor Private Structure */
+struct zx2967_thermal_priv {
+	/* struct thermal_zone_device where the sensor is registered */
+	struct thermal_zone_device	*tzd;
+	/* prevents reads sensor in parallel */
+	struct mutex			lock;
+	/* topcrm clk structure */
+	struct clk			*clk_topcrm;
+	/* apb clk structure */
+	struct clk			*clk_apb;
+	/* pointer to base address of the thermal sensor */
+	void __iomem			*regs;
+	struct device			*dev;
+};
+
+static int zx2967_thermal_get_temp(void *data, int *temp)
+{
+	void __iomem *regs;
+	struct zx2967_thermal_priv *priv = data;
+	u32 val;
+	int ret;
+
+	if (!priv->tzd)
+		return -EAGAIN;
+
+	regs = priv->regs;
+	mutex_lock(&priv->lock);
+	writel_relaxed(ZX2967_POWER_MODE_LOW,
+		       regs + ZX2967_THERMAL_POWER_MODE);
+	writel_relaxed(ZX2967_DCF_EN, regs + ZX2967_THERMAL_DCF);
+
+	val = readl_relaxed(regs + ZX2967_THERMAL_SEL);
+	val &= ~ZX2967_THERMAL_ID_MASK;
+	val |= ZX2967_THERMAL_ID;
+	writel_relaxed(val, regs + ZX2967_THERMAL_SEL);
+
+	/*
+	 * Must wait for a while, surely it's a bit odd.
+	 * otherwise temperature value we got has a few deviation, even if
+	 * the THERMAL_READY bit is set.
+	 */
+	usleep_range(100, 300);
+	ret = readx_poll_timeout(readl, regs + ZX2967_THERMAL_CTRL,
+				 val, val & ZX2967_THERMAL_READY, 300,
+				 ZX2967_GET_TEMP_TIMEOUT_US);
+	if (ret) {
+		dev_err(priv->dev, "Thermal sensor data timeout\n");
+		goto unlock;
+	}
+
+	writel_relaxed(ZX2967_DCF_FREEZE | ZX2967_DCF_EN,
+		       regs + ZX2967_THERMAL_DCF);
+	val = readl_relaxed(regs + ZX2967_THERMAL_CTRL)
+			 & ZX2967_THERMAL_TEMP_MASK;
+	writel_relaxed(ZX2967_POWER_MODE_HIGH,
+		       regs + ZX2967_THERMAL_POWER_MODE);
+
+	/*
+	 * Calculate temperature
+	 * In dts, slope is multiplied by 1000.
+	 */
+	*temp = DIV_ROUND_CLOSEST(((s32)val + priv->tzd->tzp->offset) * 1000,
+				  priv->tzd->tzp->slope);
+
+unlock:
+	mutex_unlock(&priv->lock);
+	return ret;
+}
+
+static struct thermal_zone_of_device_ops zx2967_of_thermal_ops = {
+	.get_temp = zx2967_thermal_get_temp,
+};
+
+static int zx2967_thermal_probe(struct platform_device *pdev)
+{
+	struct zx2967_thermal_priv *priv;
+	struct resource *res;
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	priv->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(priv->regs))
+		return PTR_ERR(priv->regs);
+
+	priv->clk_topcrm = devm_clk_get(&pdev->dev, "topcrm");
+	if (IS_ERR(priv->clk_topcrm)) {
+		ret = PTR_ERR(priv->clk_topcrm);
+		dev_err(&pdev->dev, "failed to get topcrm clock: %d\n", ret);
+		return ret;
+	}
+
+	ret = clk_prepare_enable(priv->clk_topcrm);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to enable topcrm clock: %d\n",
+			ret);
+		return ret;
+	}
+
+	priv->clk_apb = devm_clk_get(&pdev->dev, "apb");
+	if (IS_ERR(priv->clk_apb)) {
+		ret = PTR_ERR(priv->clk_apb);
+		dev_err(&pdev->dev, "failed to get apb clock: %d\n", ret);
+		goto disable_clk_topcrm;
+	}
+
+	ret = clk_prepare_enable(priv->clk_apb);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to enable apb clock: %d\n",
+			ret);
+		goto disable_clk_topcrm;
+	}
+
+	mutex_init(&priv->lock);
+	priv->tzd = thermal_zone_of_sensor_register(&pdev->dev,
+					0, priv, &zx2967_of_thermal_ops);
+
+	if (IS_ERR(priv->tzd)) {
+		ret = PTR_ERR(priv->tzd);
+		dev_err(&pdev->dev, "failed to register sensor: %d\n", ret);
+		goto disable_clk_all;
+	}
+
+	if (priv->tzd->tzp->slope == 0) {
+		thermal_zone_of_sensor_unregister(&pdev->dev, priv->tzd);
+		dev_err(&pdev->dev, "coefficients of sensor is invalid\n");
+		ret = -EINVAL;
+		goto disable_clk_all;
+	}
+
+	priv->dev = &pdev->dev;
+	platform_set_drvdata(pdev, priv);
+
+	return 0;
+
+disable_clk_all:
+	clk_disable_unprepare(priv->clk_apb);
+disable_clk_topcrm:
+	clk_disable_unprepare(priv->clk_topcrm);
+	return ret;
+}
+
+static int zx2967_thermal_exit(struct platform_device *pdev)
+{
+	struct zx2967_thermal_priv *priv = platform_get_drvdata(pdev);
+
+	thermal_zone_of_sensor_unregister(&pdev->dev, priv->tzd);
+	clk_disable_unprepare(priv->clk_topcrm);
+	clk_disable_unprepare(priv->clk_apb);
+
+	return 0;
+}
+
+static const struct of_device_id zx2967_thermal_id_table[] = {
+	{ .compatible = "zte,zx296718-thermal" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, zx2967_thermal_id_table);
+
+#ifdef CONFIG_PM_SLEEP
+static int zx2967_thermal_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct zx2967_thermal_priv *priv = platform_get_drvdata(pdev);
+
+	if (priv && priv->clk_topcrm)
+		clk_disable_unprepare(priv->clk_topcrm);
+
+	if (priv && priv->clk_apb)
+		clk_disable_unprepare(priv->clk_apb);
+
+	return 0;
+}
+
+static int zx2967_thermal_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct zx2967_thermal_priv *priv = platform_get_drvdata(pdev);
+	int error;
+
+	error = clk_prepare_enable(priv->clk_topcrm);
+	if (error)
+		return error;
+
+	error = clk_prepare_enable(priv->clk_apb);
+	if (error) {
+		clk_disable_unprepare(priv->clk_topcrm);
+		return error;
+	}
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(zx2967_thermal_pm_ops,
+			 zx2967_thermal_suspend, zx2967_thermal_resume);
+
+static struct platform_driver zx2967_thermal_driver = {
+	.probe = zx2967_thermal_probe,
+	.remove = zx2967_thermal_exit,
+	.driver = {
+		.name = "zx2967_thermal",
+		.of_match_table = zx2967_thermal_id_table,
+		.pm = &zx2967_thermal_pm_ops,
+	},
+};
+module_platform_driver(zx2967_thermal_driver);
+
+MODULE_AUTHOR("Baoyou Xie <baoyou.xie@linaro.org>");
+MODULE_DESCRIPTION("ZTE zx2967 thermal driver");
+MODULE_LICENSE("GPL v2");