[PATCH v1 0/2] Add JHB100 Fan-Tach support

[PATCH v1 0/2] Add JHB100 Fan-Tach support

[Changhuang Liang]

StarFive Fan-Tach controller can support up to 16 fan tach input.
The series has been tested on the EVB1 board.

Changhuang Liang (2):
  dt-bindings: hwmon: Add starfive,jhb100-fan-tach
  hwmon: Add fan tach driver for StarFive

 .../hwmon/starfive,jhb100-fan-tach.yaml       |  98 ++++
 MAINTAINERS                                   |   6 +
 drivers/hwmon/Kconfig                         |   9 +
 drivers/hwmon/Makefile                        |   1 +
 drivers/hwmon/starfive-fan-tach.c             | 467 ++++++++++++++++++
 5 files changed, 581 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/starfive,jhb100-fan-tach.yaml
 create mode 100644 drivers/hwmon/starfive-fan-tach.c

--
2.25.1

[PATCH v1 1/2] dt-bindings: hwmon: Add starfive,jhb100-fan-tach

[Changhuang Liang]

Add compatible "starfive,jhb100-fan-tach" for StarFive JHB100 Fan-Tach
controller.

Signed-off-by: Changhuang Liang <changhuang.liang@starfivetech.com>
---
 .../hwmon/starfive,jhb100-fan-tach.yaml       | 98 +++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/starfive,jhb100-fan-tach.yaml

diff --git a/Documentation/devicetree/bindings/hwmon/starfive,jhb100-fan-tach.yaml b/Documentation/devicetree/bindings/hwmon/starfive,jhb100-fan-tach.yaml
new file mode 100644
index 000000000000..fdc8539ec804
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/starfive,jhb100-fan-tach.yaml
@@ -0,0 +1,98 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwmon/starfive,jhb100-fan-tach.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: StarFive JHB100 Fan-Tach controller
+
+maintainers:
+  - Changhuang Liang <changhuang.liang@starfivetech.com>
+
+description:
+  The StarFive Fan-Tach controller can support up to 16 fan tach input.
+
+properties:
+  compatible:
+    enum:
+      - starfive,jhb100-fan-tach
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  resets:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+patternProperties:
+  "^fan@[0-9]+$":
+    $ref: fan-common.yaml#
+    unevaluatedProperties: false
+    required:
+      - reg
+      - tach-ch
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - resets
+  - interrupts
+
+additionalProperties: false
+
+examples:
+  - |
+    fan-tach-controller@11be0000 {
+        compatible = "starfive,jhb100-fan-tach";
+        reg = <0x11be0000 0x400>;
+        interrupts = <128>;
+        clocks = <&per2crg 33>;
+        resets = <&per2crg 5>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        fan@0 {
+            reg = <0>;
+            tach-ch = /bits/ 8 <0x0>, <0x8>;
+        };
+        fan@1 {
+            reg = <1>;
+            tach-ch = /bits/ 8 <0x1>, <0x9>;
+        };
+        fan@2 {
+            reg = <2>;
+            tach-ch = /bits/ 8 <0x2>, <0xa>;
+        };
+        fan@3 {
+            reg = <3>;
+            tach-ch = /bits/ 8 <0x3>, <0xb>;
+        };
+        fan@4 {
+            reg = <4>;
+            tach-ch = /bits/ 8 <0x4>, <0xc>;
+        };
+        fan@5 {
+            reg = <5>;
+            tach-ch = /bits/ 8 <0x5>, <0xd>;
+        };
+        fan@6 {
+            reg = <6>;
+            tach-ch = /bits/ 8 <0x6>, <0xe>;
+        };
+        fan@7 {
+            reg = <7>;
+            tach-ch = /bits/ 8 <0x7>, <0xf>;
+        };
+    };
-- 
2.25.1

[PATCH v1 2/2] hwmon: Add fan tach driver for StarFive

[Changhuang Liang]

Add fan tach driver for StarFive JHB100 SoC.

Signed-off-by: Changhuang Liang <changhuang.liang@starfivetech.com>
---
 MAINTAINERS                       |   6 +
 drivers/hwmon/Kconfig             |   9 +
 drivers/hwmon/Makefile            |   1 +
 drivers/hwmon/starfive-fan-tach.c | 467 ++++++++++++++++++++++++++++++
 4 files changed, 483 insertions(+)
 create mode 100644 drivers/hwmon/starfive-fan-tach.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 2fb1c75afd16..72c1e093b865 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -25539,6 +25539,12 @@ S:	Supported
 F:	Documentation/devicetree/bindings/interrupt-controller/starfive,jh8100-intc.yaml
 F:	drivers/irqchip/irq-starfive-jh8100-intc.c
 
+STARFIVE JHB100 FAN-TACH DRIVER
+M:	Changhuang Liang <changhuang.liang@starfivetech.com>
+S:	Supported
+F:	Documentation/devicetree/bindings/hwmon/starfive,jhb100-fan-tach.yaml
+F:	drivers/hwmon/starfive-fan-tach.c
+
 STATIC BRANCH/CALL
 M:	Peter Zijlstra <peterz@infradead.org>
 M:	Josh Poimboeuf <jpoimboe@kernel.org>
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 14e4cea48acc..85cd34a635fb 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -2338,6 +2338,15 @@ config SENSORS_SPD5118_DETECT
 
 	  If unsure, say Y.
 
+config SENSORS_STARFIVE_FAN_TACH
+	tristate "StarFive Fan-Tach driver"
+	depends on ARCH_STARFIVE || COMPILE_TEST
+	help
+	  This driver provides support for StarFive Fan-Tach controllers.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called starfive-fan-tach.
+
 config SENSORS_TC74
 	tristate "Microchip TC74"
 	depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 4788996aa137..ff0bb789defc 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -220,6 +220,7 @@ obj-$(CONFIG_SENSORS_SMSC47M1)	+= smsc47m1.o
 obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
 obj-$(CONFIG_SENSORS_SPARX5)	+= sparx5-temp.o
 obj-$(CONFIG_SENSORS_SPD5118)	+= spd5118.o
+obj-$(CONFIG_SENSORS_STARFIVE_FAN_TACH)	+= starfive-fan-tach.o
 obj-$(CONFIG_SENSORS_STTS751)	+= stts751.o
 obj-$(CONFIG_SENSORS_SURFACE_FAN)+= surface_fan.o
 obj-$(CONFIG_SENSORS_SURFACE_TEMP)+= surface_temp.o
diff --git a/drivers/hwmon/starfive-fan-tach.c b/drivers/hwmon/starfive-fan-tach.c
new file mode 100644
index 000000000000..394c562d2267
--- /dev/null
+++ b/drivers/hwmon/starfive-fan-tach.c
@@ -0,0 +1,467 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * FAN-TACH controller driver for StarFive JHB100
+ *
+ * Copyright (C) 2018-2024 StarFive Technology Co., Ltd.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/errno.h>
+#include <linux/hwmon.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+#include <linux/sysfs.h>
+
+#define STARFIVE_FAN_TACH_CH			16
+
+/* Fan-tach register offest */
+#define STARFIVE_FAN_TACH_STATUS		0x0c
+
+#define STARFIVE_FAN_TACH_SPEED(ch)		(((ch) * 0x04) + 0x10)
+#define STARFIVE_FAN_TACH_SPEED_VALID		BIT(31)
+#define STARFIVE_FAN_TACH_VALUE_MASK		GENMASK(30, 0)
+
+#define STARFIVE_FAN_TACH_THRESHOLD(ch)		(((ch) * 0x04) + 0x50)
+
+#define STARFIVE_FAN_TACH_INT_EN		0x90
+#define STARFIVE_FAN_TACH_STALL_INT_MASK	GENMASK(15, 0)
+#define STARFIVE_FAN_TACH_SLOW_INT_MASK		GENMASK(31, 16)
+#define STARFIVE_FAN_TACH_STALL_INT(ch)		BIT(ch)
+#define STARFIVE_FAN_TACH_SLOW_INT(ch)		(BIT(ch) << 16)
+
+#define STARFIVE_FAN_TACH_MEASURE_TIME		0x94
+
+#define STARFIVE_FAN_TACH_CH_EN			0x98
+#define STARFIVE_FAN_TACH_EN(ch)		BIT(ch)
+
+#define STARFIVE_FAN_DEFAULT_PULSE_PR		2
+#define STARFIVE_FAN_DEFAULT_MEASURE_RATIO	2
+#define STARFIVE_FAN_DEFAULT_RPM_PAUSE_TIME	(60 * STARFIVE_FAN_DEFAULT_MEASURE_RATIO)
+
+#define STARFIVE_FAN_TACH_TIMEOUT \
+	(USEC_PER_SEC / STARFIVE_FAN_DEFAULT_MEASURE_RATIO)
+
+#define STARFIVE_FAN_TACH_TIMEOUT_JIFFIES \
+	(msecs_to_jiffies(1000) / STARFIVE_FAN_DEFAULT_MEASURE_RATIO)
+
+#define FAN_ATTRIBUTE_SET \
+	(HWMON_F_INPUT | HWMON_F_MIN | HWMON_F_ENABLE | \
+	 HWMON_F_FAULT | HWMON_F_MIN_ALARM)
+
+struct starfive_fan_tach_data {
+	struct device *dev;
+	void __iomem *regs;
+	bool tach_present[STARFIVE_FAN_TACH_CH];
+	u32 clk_rate; /* APB clock frequency */
+	struct completion comp_stall[STARFIVE_FAN_TACH_CH];
+	struct completion comp_slow[STARFIVE_FAN_TACH_CH];
+	u8 fan_stall[STARFIVE_FAN_TACH_CH];
+	u8 fan_slow[STARFIVE_FAN_TACH_CH];
+};
+
+static void starfive_fan_tach_ch_enable(struct starfive_fan_tach_data *priv, u8 tach_ch,
+					bool enable)
+{
+	if (enable) {
+		writel(readl(priv->regs + STARFIVE_FAN_TACH_CH_EN) |
+		       STARFIVE_FAN_TACH_EN(tach_ch),
+		       priv->regs + STARFIVE_FAN_TACH_CH_EN);
+	} else {
+		writel(readl(priv->regs + STARFIVE_FAN_TACH_CH_EN) &
+		       ~(STARFIVE_FAN_TACH_EN(tach_ch)),
+		       priv->regs + STARFIVE_FAN_TACH_CH_EN);
+	}
+}
+
+static void starfive_fan_tach_ch_stall_unmask(struct starfive_fan_tach_data *priv, u8 tach_ch,
+					      bool unmask)
+{
+	if (unmask) {
+		writel(readl(priv->regs + STARFIVE_FAN_TACH_INT_EN) |
+		       STARFIVE_FAN_TACH_STALL_INT(tach_ch),
+		       priv->regs + STARFIVE_FAN_TACH_INT_EN);
+	} else {
+		writel(readl(priv->regs + STARFIVE_FAN_TACH_INT_EN) &
+		       ~STARFIVE_FAN_TACH_STALL_INT(tach_ch),
+		       priv->regs + STARFIVE_FAN_TACH_INT_EN);
+	}
+}
+
+static void starfive_fan_tach_ch_slow_unmask(struct starfive_fan_tach_data *priv, u8 tach_ch,
+					     bool unmask)
+{
+	if (unmask) {
+		writel(readl(priv->regs + STARFIVE_FAN_TACH_INT_EN) |
+		       STARFIVE_FAN_TACH_SLOW_INT(tach_ch),
+		       priv->regs + STARFIVE_FAN_TACH_INT_EN);
+	} else {
+		writel(readl(priv->regs + STARFIVE_FAN_TACH_INT_EN) &
+		       ~STARFIVE_FAN_TACH_SLOW_INT(tach_ch),
+		       priv->regs + STARFIVE_FAN_TACH_INT_EN);
+	}
+}
+
+static int starfive_fan_tach_rpm_to_val(struct starfive_fan_tach_data *priv, u32 rpm)
+{
+	u64 tach_val;
+
+	rpm *= STARFIVE_FAN_DEFAULT_PULSE_PR;
+	tach_val = rpm / STARFIVE_FAN_DEFAULT_RPM_PAUSE_TIME;
+
+	return (int)tach_val;
+}
+
+static int starfive_fan_tach_val_to_rpm(struct starfive_fan_tach_data *priv, u32 tach_val)
+{
+	u64 rpm;
+
+	rpm = tach_val * STARFIVE_FAN_DEFAULT_RPM_PAUSE_TIME;
+
+	do_div(rpm, STARFIVE_FAN_DEFAULT_PULSE_PR);
+
+	return (int)rpm;
+}
+
+static int starfive_fan_tach_get_rpm(struct starfive_fan_tach_data *priv,
+				     u8 fan_tach_ch)
+{
+	u32 val;
+	int ret;
+
+	ret = readl_poll_timeout(priv->regs + STARFIVE_FAN_TACH_SPEED(fan_tach_ch),
+				 val, val & STARFIVE_FAN_TACH_SPEED_VALID,
+				 100, STARFIVE_FAN_TACH_TIMEOUT);
+	if (ret)
+		return ret;
+
+	val = FIELD_GET(STARFIVE_FAN_TACH_VALUE_MASK, val);
+
+	return starfive_fan_tach_val_to_rpm(priv, val);
+}
+
+static int starfive_fan_tach_get_rpm_threshold(struct starfive_fan_tach_data *priv,
+					       u8 fan_tach_ch)
+{
+	u32 val;
+
+	val = readl(priv->regs + STARFIVE_FAN_TACH_THRESHOLD(fan_tach_ch));
+
+	val = FIELD_GET(STARFIVE_FAN_TACH_VALUE_MASK, val);
+
+	return starfive_fan_tach_val_to_rpm(priv, (int)val);
+}
+
+static void starfive_set_tach_rpm_threshold(struct starfive_fan_tach_data *priv,
+					    u8 fan_tach_ch, u32 val)
+{
+	val = clamp_val(starfive_fan_tach_rpm_to_val(priv, val), 1, STARFIVE_FAN_TACH_VALUE_MASK);
+
+	writel(val, priv->regs + STARFIVE_FAN_TACH_THRESHOLD(fan_tach_ch));
+}
+
+static int starfive_fan_tach_get_ch_en(struct starfive_fan_tach_data *priv,
+				       u8 fan_tach_ch)
+{
+	u32 enable;
+
+	enable = readl(priv->regs + STARFIVE_FAN_TACH_CH_EN);
+
+	return (enable & (1 << fan_tach_ch)) ? 1 : 0;
+}
+
+static void starfive_fan_tach_set_ch_en(struct starfive_fan_tach_data *priv,
+					u8 fan_tach_ch, u32 val)
+{
+	bool enable;
+
+	switch (val) {
+	case 0:
+		enable = false;
+		break;
+	case 1:
+		enable = true;
+		break;
+	default:
+		return;
+	}
+
+	starfive_fan_tach_ch_enable(priv, fan_tach_ch, enable);
+}
+
+static int starfive_fan_tach_hwmon_read(struct device *dev,
+					enum hwmon_sensor_types type, u32 attr,
+					int channel, long *val)
+{
+	struct starfive_fan_tach_data *priv = dev_get_drvdata(dev);
+
+	switch (attr) {
+	case hwmon_fan_fault:
+		starfive_fan_tach_ch_stall_unmask(priv, channel, true);
+		/* clear fan_stall first */
+		priv->fan_stall[channel] = 0;
+		reinit_completion(&priv->comp_stall[channel]);
+		wait_for_completion_timeout(&priv->comp_stall[channel],
+					    2 * STARFIVE_FAN_TACH_TIMEOUT_JIFFIES);
+		*val = priv->fan_stall[channel];
+		starfive_fan_tach_ch_stall_unmask(priv, channel, false);
+		break;
+	case hwmon_fan_input:
+		*val = starfive_fan_tach_get_rpm(priv, channel);
+		break;
+	case hwmon_fan_min:
+		*val = starfive_fan_tach_get_rpm_threshold(priv, channel);
+		break;
+	case hwmon_fan_min_alarm:
+		starfive_fan_tach_ch_slow_unmask(priv, channel, true);
+		/* clear fan_slow first */
+		priv->fan_slow[channel] = 0;
+		reinit_completion(&priv->comp_slow[channel]);
+		wait_for_completion_timeout(&priv->comp_stall[channel],
+					    2 * STARFIVE_FAN_TACH_TIMEOUT_JIFFIES);
+		*val = priv->fan_slow[channel];
+		starfive_fan_tach_ch_slow_unmask(priv, channel, false);
+		break;
+	case hwmon_fan_enable:
+		*val = starfive_fan_tach_get_ch_en(priv, channel);
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int starfive_fan_tach_hwmon_write(struct device *dev,
+					 enum hwmon_sensor_types type, u32 attr,
+					 int channel, long val)
+{
+	struct starfive_fan_tach_data *priv = dev_get_drvdata(dev);
+
+	switch (attr) {
+	case hwmon_fan_min:
+		starfive_set_tach_rpm_threshold(priv, channel, (u32)val);
+		break;
+	case hwmon_fan_enable:
+		starfive_fan_tach_set_ch_en(priv, channel, (u32)val);
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static umode_t starfive_fan_tach_dev_is_visible(const void *drvdata,
+						enum hwmon_sensor_types type,
+						u32 attr, int channel)
+{
+	const struct starfive_fan_tach_data *priv = drvdata;
+
+	if (!priv->tach_present[channel])
+		return 0;
+
+	switch (attr) {
+	case hwmon_fan_input:
+	case hwmon_fan_fault:
+	case hwmon_fan_min_alarm:
+		return 0444;
+	case hwmon_fan_min:
+	case hwmon_fan_pulses:
+	case hwmon_fan_enable:
+		return 0644;
+	}
+
+	return 0;
+}
+
+static const struct hwmon_ops starfive_fan_tach_ops = {
+	.is_visible = starfive_fan_tach_dev_is_visible,
+	.read = starfive_fan_tach_hwmon_read,
+	.write = starfive_fan_tach_hwmon_write
+};
+
+static const struct hwmon_channel_info *starfive_fan_tach_info[] = {
+	HWMON_CHANNEL_INFO(fan,
+			   FAN_ATTRIBUTE_SET, FAN_ATTRIBUTE_SET,
+			   FAN_ATTRIBUTE_SET, FAN_ATTRIBUTE_SET,
+			   FAN_ATTRIBUTE_SET, FAN_ATTRIBUTE_SET,
+			   FAN_ATTRIBUTE_SET, FAN_ATTRIBUTE_SET,
+			   FAN_ATTRIBUTE_SET, FAN_ATTRIBUTE_SET,
+			   FAN_ATTRIBUTE_SET, FAN_ATTRIBUTE_SET,
+			   FAN_ATTRIBUTE_SET, FAN_ATTRIBUTE_SET,
+			   FAN_ATTRIBUTE_SET, FAN_ATTRIBUTE_SET),
+	NULL
+};
+
+static const struct hwmon_chip_info starfive_fan_tach_chip_info = {
+	.ops = &starfive_fan_tach_ops,
+	.info = starfive_fan_tach_info,
+};
+
+static void starfive_fan_tach_present(struct starfive_fan_tach_data *priv, u8 *tach_ch,
+				      int count)
+{
+	u8 ch, index;
+
+	for (index = 0; index < count; index++) {
+		ch = tach_ch[index];
+		priv->tach_present[ch] = true;
+
+		starfive_fan_tach_ch_enable(priv, ch, true);
+		init_completion(&priv->comp_stall[ch]);
+		init_completion(&priv->comp_slow[ch]);
+	}
+}
+
+static int starfive_fan_tach_create_fan(struct device *dev, struct device_node *child,
+					struct starfive_fan_tach_data *priv)
+{
+	int ret, count;
+	u8 *tach_ch;
+
+	count = of_property_count_u8_elems(child, "tach-ch");
+	if (count < 1)
+		return -EINVAL;
+
+	tach_ch = devm_kcalloc(dev, count, sizeof(*tach_ch), GFP_KERNEL);
+	if (!tach_ch)
+		return -ENOMEM;
+
+	ret = of_property_read_u8_array(child, "tach-ch", tach_ch, count);
+	if (ret)
+		return ret;
+
+	starfive_fan_tach_present(priv, tach_ch, count);
+
+	return 0;
+}
+
+static irqreturn_t starfive_fan_tach_irq(int irq, void *dev_id)
+{
+	struct starfive_fan_tach_data *priv = dev_id;
+	u32 fan_status;
+	int i;
+
+	fan_status = readl(priv->regs + STARFIVE_FAN_TACH_STATUS);
+
+	for (i = 0; i < STARFIVE_FAN_TACH_CH; i++) {
+		if (fan_status & STARFIVE_FAN_TACH_STALL_INT(i)) {
+			priv->fan_stall[i] = 1;
+			complete(&priv->comp_stall[i]);
+		}
+
+		if (fan_status & STARFIVE_FAN_TACH_SLOW_INT(i)) {
+			priv->fan_slow[i] = 1;
+			complete(&priv->comp_slow[i]);
+		}
+	}
+
+	writel(fan_status, priv->regs + STARFIVE_FAN_TACH_STATUS);
+
+	return IRQ_HANDLED;
+}
+
+static void starfive_fan_tach_reset_control_assert(void *data)
+{
+	reset_control_assert(data);
+}
+
+static int starfive_fan_tach_probe(struct platform_device *pdev)
+{
+	struct device *hwmon_dev, *dev = &pdev->dev;
+	struct starfive_fan_tach_data *priv;
+	struct reset_control *rst;
+	struct clk *clk;
+	int irq;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->dev = dev;
+
+	priv->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->regs))
+		return dev_err_probe(dev, PTR_ERR(priv->regs),
+				     "Unable to map IO resources\n");
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return dev_err_probe(dev, irq, "Failed to get IRQ\n");
+
+	ret = devm_request_irq(dev, irq, starfive_fan_tach_irq, 0, pdev->name,
+			       (void *)priv);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to register interrupt handler\n");
+
+	rst = devm_reset_control_get_exclusive(dev, NULL);
+	if (IS_ERR(rst))
+		return dev_err_probe(dev, PTR_ERR(rst),
+				     "Unable to get fan tach's reset\n");
+
+	clk = devm_clk_get_enabled(dev, NULL);
+	if (IS_ERR(clk))
+		return dev_err_probe(dev, PTR_ERR(clk),
+				     "Unable to get & enable fan tach's clock\n");
+
+	priv->clk_rate = clk_get_rate(clk);
+	if (priv->clk_rate <= 0)
+		return dev_err_probe(dev, priv->clk_rate,
+				     "Unable to get clock's rate\n");
+
+	reset_control_deassert(rst);
+	ret = devm_add_action_or_reset(dev, starfive_fan_tach_reset_control_assert, rst);
+	if (ret)
+		return ret;
+
+	writel(STARFIVE_FAN_TACH_STALL_INT_MASK | STARFIVE_FAN_TACH_SLOW_INT_MASK,
+	       priv->regs + STARFIVE_FAN_TACH_STATUS);
+	writel(priv->clk_rate / STARFIVE_FAN_DEFAULT_MEASURE_RATIO,
+	       priv->regs + STARFIVE_FAN_TACH_MEASURE_TIME);
+
+	for_each_child_of_node_scoped(dev->of_node, child) {
+		ret = starfive_fan_tach_create_fan(dev, child, priv);
+		if (ret < 0) {
+			dev_warn(dev, "Failed to create fan %d", ret);
+			return 0;
+		}
+	}
+
+	platform_set_drvdata(pdev, priv);
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, "starfive_fan_tach",
+							 priv, &starfive_fan_tach_chip_info,
+							 NULL);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct of_device_id starfive_fan_tach_of_match[] = {
+	{ .compatible = "starfive,jhb100-fan-tach", },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver starfive_fan_tach_driver = {
+	.probe = starfive_fan_tach_probe,
+	.driver	= {
+		.name = "starfive-fan-tach",
+		.of_match_table = starfive_fan_tach_of_match,
+	},
+};
+
+module_platform_driver(starfive_fan_tach_driver);
+
+MODULE_AUTHOR("William Qiu <william.qiu@starfivetech.com>");
+MODULE_AUTHOR("Changhuang Liang <changhuang.liang@starfivetech.com>");
+MODULE_DESCRIPTION("StarFive JHB100 Fan Tach device driver");
+MODULE_LICENSE("GPL");
-- 
2.25.1