[PATCH v2 0/2] Add JHB100 Fan-Tach support

[PATCH v2 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.

Change since v1:
PATCH 1:
- Add explicit minItems/maxItems and range constraints for tach-ch.
- Switch fan node regex to support hex addresses.
- Add pulses-per-revolution demo.
- Rename example node to fan-controller for consistency.
- Limit the reg property to a maximum value of 15
- Fix tach-ch example by changing /bits/ 8 <0x0>, <0x8> to
  /bits/ 8 <0x0 0x8> so both values are parsed as 8-bit cells.

PATCH 2:
- Added hwmon documentation (starfive-fan-tach.rst)
- Added HAS_IOMEM dependency in Kconfig
- Added per-channel pulses-per-revolution DT property (default 2, range 1-4)
- Added mutex and spinlock for proper concurrency protection
- Added armed_stall/armed_slow mechanism to prevent spurious interrupts
- Added retry logic for zero sampling value in rpm read
- Improved probe sequence: clock enable before reset deassert
- Added devm action for remove path cleanup
- Added input validation for write operations
- Added MODULE_DEVICE_TABLE
- Added linux-hwmon mailing list to MAINTAINERS

v1: https://lore.kernel.org/all/20260428082337.743546-1-changhuang.liang@starfivetech.com/

Changhuang Liang (2):
  dt-bindings: hwmon: Add starfive,jhb100-fan-tach
  hwmon: (starfive-fan-tach) Add fan tach driver for StarFive JHB100

 .../hwmon/starfive,jhb100-fan-tach.yaml       |  93 +++
 Documentation/hwmon/index.rst                 |   1 +
 Documentation/hwmon/starfive-fan-tach.rst     |  34 ++
 MAINTAINERS                                   |   8 +
 drivers/hwmon/Kconfig                         |  14 +
 drivers/hwmon/Makefile                        |   1 +
 drivers/hwmon/starfive-fan-tach.c             | 561 ++++++++++++++++++
 7 files changed, 712 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/starfive,jhb100-fan-tach.yaml
 create mode 100644 Documentation/hwmon/starfive-fan-tach.rst
 create mode 100644 drivers/hwmon/starfive-fan-tach.c

--
2.25.1

[PATCH v2 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       | 93 +++++++++++++++++++
 1 file changed, 93 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..1dcd4932768f
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/starfive,jhb100-fan-tach.yaml
@@ -0,0 +1,93 @@
+# 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@[0-9a-f]+$":
+    $ref: fan-common.yaml#
+    unevaluatedProperties: false
+
+    properties:
+      reg:
+        description:
+          PWM channel index. The driver allows two fans to share the same
+          PWM channel, or each fan to use a dedicated channel.
+        maximum: 15
+
+      tach-ch:
+        description:
+          The tachometer channel(s) wired to the fan(s) driven by this PWM
+          channel. Integer values in the range 0-15.
+        minItems: 1
+        maxItems: 2
+        items:
+          maximum: 15
+
+    required:
+      - reg
+      - tach-ch
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - resets
+  - interrupts
+
+additionalProperties: false
+
+examples:
+  - |
+    fan-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 = <0x0>;
+            tach-ch = /bits/ 8 <0x0 0x8>;
+            pulses-per-revolution = <2>;
+        };
+        fan@1 {
+            reg = <0x1>;
+            tach-ch = /bits/ 8 <0x1>;
+            pulses-per-revolution = <2>;
+        };
+    };
-- 
2.25.1