[PATCH v3 2/2] hwmon: (sfctemp) Add StarFive JH7100 temperature sensor

[Emil Renner Berthing <kernel@esmil.dk>]

Register definitions and conversion constants based on sfctemp driver by
Samin in the StarFive 5.10 kernel.

Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
Signed-off-by: Samin Guo <samin.guo@starfivetech.com>
---
 Documentation/hwmon/index.rst   |   1 +
 Documentation/hwmon/sfctemp.rst |  32 ++++
 MAINTAINERS                     |   8 +
 drivers/hwmon/Kconfig           |  10 ++
 drivers/hwmon/Makefile          |   1 +
 drivers/hwmon/sfctemp.c         | 291 ++++++++++++++++++++++++++++++++
 6 files changed, 343 insertions(+)
 create mode 100644 Documentation/hwmon/sfctemp.rst
 create mode 100644 drivers/hwmon/sfctemp.c

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index bc01601ea81a..961b6d93bead 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -164,6 +164,7 @@ Hardware Monitoring Kernel Drivers
    sch5627
    sch5636
    scpi-hwmon
+   sfctemp
    sht15
    sht21
    sht3x
diff --git a/Documentation/hwmon/sfctemp.rst b/Documentation/hwmon/sfctemp.rst
new file mode 100644
index 000000000000..465edce2fea5
--- /dev/null
+++ b/Documentation/hwmon/sfctemp.rst
@@ -0,0 +1,32 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver sfctemp
+=====================
+
+Supported chips:
+ - StarFive JH7100
+
+Authors:
+ - Emil Renner Berthing <kernel@esmil.dk>
+
+Description
+-----------
+
+This driver adds support for reading the built-in temperature sensor on the
+JH7100 RISC-V SoC by StarFive Technology Co. Ltd.
+
+``sysfs`` interface
+-------------------
+
+The temperature sensor can be enabled, disabled and queried via the standard
+hwmon interface in sysfs under ``/sys/class/hwmon/hwmonX`` for some value of
+``X``:
+
+================ ==== =============================================
+Name             Perm Description
+================ ==== =============================================
+temp1_enable     RW   Enable or disable temperature sensor.
+                      Automatically enabled by the driver,
+                      but may be disabled to save power.
+temp1_input      RO   Temperature reading in milli-degrees Celsius.
+================ ==== =============================================
diff --git a/MAINTAINERS b/MAINTAINERS
index 19135a9d778e..6fb1fd015c19 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16751,6 +16751,14 @@ L:	netdev@vger.kernel.org
 S:	Supported
 F:	drivers/net/ethernet/sfc/
 
+SFCTEMP HWMON DRIVER
+M:	Emil Renner Berthing <kernel@esmil.dk>
+L:	linux-hwmon@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/hwmon/starfive,jh7100-temp.yaml
+F:	Documentation/hwmon/sfctemp.rst
+F:	drivers/hwmon/sfctemp.c
+
 SFF/SFP/SFP+ MODULE SUPPORT
 M:	Russell King <linux@armlinux.org.uk>
 L:	netdev@vger.kernel.org
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index e3675377bc5d..ef3e345d6ce3 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1762,6 +1762,16 @@ config SENSORS_STTS751
 	  This driver can also be built as a module. If so, the module
 	  will be called stts751.
 
+config SENSORS_SFCTEMP
+	tristate "Starfive JH7100 temperature sensor"
+	depends on OF && (RISCV || COMPILE_TEST)
+	help
+	  If you say yes here you get support for temperature sensor
+	  on the Starfive JH7100 SoC.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called sfctemp.
+
 config SENSORS_SMM665
 	tristate "Summit Microelectronics SMM665"
 	depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index d712c61c1f5e..869f8806561e 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -167,6 +167,7 @@ obj-$(CONFIG_SENSORS_SBTSI)	+= sbtsi_temp.o
 obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
 obj-$(CONFIG_SENSORS_SCH5627)	+= sch5627.o
 obj-$(CONFIG_SENSORS_SCH5636)	+= sch5636.o
+obj-$(CONFIG_SENSORS_SFCTEMP)	+= sfctemp.o
 obj-$(CONFIG_SENSORS_SL28CPLD)	+= sl28cpld-hwmon.o
 obj-$(CONFIG_SENSORS_SHT15)	+= sht15.o
 obj-$(CONFIG_SENSORS_SHT21)	+= sht21.o
diff --git a/drivers/hwmon/sfctemp.c b/drivers/hwmon/sfctemp.c
new file mode 100644
index 000000000000..35d3ca682e50
--- /dev/null
+++ b/drivers/hwmon/sfctemp.c
@@ -0,0 +1,291 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 Emil Renner Berthing <kernel@esmil.dk>
+ * Copyright (C) 2021 Samin Guo <samin.guo@starfivetech.com>
+ */
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/hwmon.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+/*
+ * TempSensor reset. The RSTN can be de-asserted once the analog core has
+ * powered up. Trst(min 100ns)
+ * 0:reset  1:de-assert
+ */
+#define SFCTEMP_RSTN	BIT(0)
+
+/*
+ * TempSensor analog core power down. The analog core will be powered up
+ * Tpu(min 50us) after PD is de-asserted. RSTN should be held low until the
+ * analog core is powered up.
+ * 0:power up  1:power down
+ */
+#define SFCTEMP_PD	BIT(1)
+
+/*
+ * TempSensor start conversion enable.
+ * 0:disable  1:enable
+ */
+#define SFCTEMP_RUN	BIT(2)
+
+/*
+ * TempSensor conversion value output.
+ * Temp(C)=DOUT*Y/4094 - K
+ */
+#define SFCTEMP_DOUT_POS	16
+#define SFCTEMP_DOUT_MSK	GENMASK(27, 16)
+
+/* DOUT to Celcius conversion constants */
+#define SFCTEMP_Y1000	237500L
+#define SFCTEMP_Z	4094L
+#define SFCTEMP_K1000	81100L
+
+struct sfctemp {
+	/* serialize access to hardware register and enabled below */
+	struct mutex lock;
+	struct completion conversion_done;
+	void __iomem *regs;
+	bool enabled;
+};
+
+static irqreturn_t sfctemp_isr(int irq, void *data)
+{
+	struct sfctemp *sfctemp = data;
+
+	complete(&sfctemp->conversion_done);
+	return IRQ_HANDLED;
+}
+
+static void sfctemp_power_up(struct sfctemp *sfctemp)
+{
+	/* make sure we're powered down first */
+	writel(SFCTEMP_PD, sfctemp->regs);
+	udelay(1);
+
+	writel(0, sfctemp->regs);
+	/* wait t_pu(50us) + t_rst(100ns) */
+	usleep_range(60, 200);
+
+	/* de-assert reset */
+	writel(SFCTEMP_RSTN, sfctemp->regs);
+	udelay(1); /* wait t_su(500ps) */
+}
+
+static void sfctemp_power_down(struct sfctemp *sfctemp)
+{
+	writel(SFCTEMP_PD, sfctemp->regs);
+}
+
+static void sfctemp_run_single(struct sfctemp *sfctemp)
+{
+	writel(SFCTEMP_RSTN | SFCTEMP_RUN, sfctemp->regs);
+	udelay(1);
+	writel(SFCTEMP_RSTN, sfctemp->regs);
+}
+
+static int sfctemp_enable(struct sfctemp *sfctemp)
+{
+	mutex_lock(&sfctemp->lock);
+	if (sfctemp->enabled)
+		goto done;
+
+	sfctemp_power_up(sfctemp);
+	sfctemp->enabled = true;
+done:
+	mutex_unlock(&sfctemp->lock);
+	return 0;
+}
+
+static int sfctemp_disable(struct sfctemp *sfctemp)
+{
+	mutex_lock(&sfctemp->lock);
+	if (!sfctemp->enabled)
+		goto done;
+
+	sfctemp_power_down(sfctemp);
+	sfctemp->enabled = false;
+done:
+	mutex_unlock(&sfctemp->lock);
+	return 0;
+}
+
+static void sfctemp_disable_action(void *data)
+{
+	sfctemp_disable(data);
+}
+
+static int sfctemp_convert(struct sfctemp *sfctemp, long *val)
+{
+	int ret;
+
+	mutex_lock(&sfctemp->lock);
+	if (!sfctemp->enabled) {
+		ret = -ENODATA;
+		goto out;
+	}
+
+	sfctemp_run_single(sfctemp);
+
+	ret = wait_for_completion_interruptible_timeout(&sfctemp->conversion_done,
+							msecs_to_jiffies(10));
+	if (ret <= 0) {
+		if (ret == 0)
+			ret = -ETIMEDOUT;
+		goto out;
+	}
+
+	/* calculate temperature in milli Celcius */
+	*val = (long)((readl(sfctemp->regs) & SFCTEMP_DOUT_MSK) >> SFCTEMP_DOUT_POS)
+		* SFCTEMP_Y1000 / SFCTEMP_Z - SFCTEMP_K1000;
+
+	ret = 0;
+out:
+	mutex_unlock(&sfctemp->lock);
+	return ret;
+}
+
+static umode_t sfctemp_is_visible(const void *data, enum hwmon_sensor_types type,
+				  u32 attr, int channel)
+{
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_enable:
+			return 0644;
+		case hwmon_temp_input:
+			return 0444;
+		}
+		return 0;
+	default:
+		return 0;
+	}
+}
+
+static int sfctemp_read(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long *val)
+{
+	struct sfctemp *sfctemp = dev_get_drvdata(dev);
+
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_enable:
+			*val = sfctemp->enabled;
+			return 0;
+		case hwmon_temp_input:
+			return sfctemp_convert(sfctemp, val);
+		}
+		return -EINVAL;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int sfctemp_write(struct device *dev, enum hwmon_sensor_types type,
+			 u32 attr, int channel, long val)
+{
+	struct sfctemp *sfctemp = dev_get_drvdata(dev);
+
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_enable:
+			if (val == 0)
+				return sfctemp_disable(sfctemp);
+			if (val == 1)
+				return sfctemp_enable(sfctemp);
+			break;
+		}
+		return -EINVAL;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct hwmon_channel_info *sfctemp_info[] = {
+	HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
+	HWMON_CHANNEL_INFO(temp, HWMON_T_ENABLE | HWMON_T_INPUT),
+	NULL
+};
+
+static const struct hwmon_ops sfctemp_hwmon_ops = {
+	.is_visible = sfctemp_is_visible,
+	.read = sfctemp_read,
+	.write = sfctemp_write,
+};
+
+static const struct hwmon_chip_info sfctemp_chip_info = {
+	.ops = &sfctemp_hwmon_ops,
+	.info = sfctemp_info,
+};
+
+static int sfctemp_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device *hwmon_dev;
+	struct resource *mem;
+	struct sfctemp *sfctemp;
+	int ret;
+
+	sfctemp = devm_kzalloc(dev, sizeof(*sfctemp), GFP_KERNEL);
+	if (!sfctemp)
+		return -ENOMEM;
+
+	dev_set_drvdata(dev, sfctemp);
+	mutex_init(&sfctemp->lock);
+	init_completion(&sfctemp->conversion_done);
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	sfctemp->regs = devm_ioremap_resource(dev, mem);
+	if (IS_ERR(sfctemp->regs))
+		return PTR_ERR(sfctemp->regs);
+
+	ret = platform_get_irq(pdev, 0);
+	if (ret < 0)
+		return ret;
+
+	ret = devm_request_irq(dev, ret, sfctemp_isr,
+			       IRQF_SHARED, pdev->name, sfctemp);
+	if (ret) {
+		dev_err(dev, "request irq failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_add_action(dev, sfctemp_disable_action, sfctemp);
+	if (ret)
+		return ret;
+
+	ret = sfctemp_enable(sfctemp);
+	if (ret)
+		return ret;
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, pdev->name, sfctemp,
+							 &sfctemp_chip_info, NULL);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct of_device_id sfctemp_of_match[] = {
+	{ .compatible = "starfive,jh7100-temp" },
+	{ /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, sfctemp_of_match);
+
+static struct platform_driver sfctemp_driver = {
+	.driver = {
+		.name = "sfctemp",
+		.of_match_table = of_match_ptr(sfctemp_of_match),
+	},
+	.probe  = sfctemp_probe,
+};
+module_platform_driver(sfctemp_driver);
+
+MODULE_AUTHOR("Emil Renner Berthing");
+MODULE_DESCRIPTION("StarFive JH7100 temperature sensor driver");
+MODULE_LICENSE("GPL");
-- 
2.32.0