pwm: intel: Add PWM driver for a new SoC

Patch 1 adds dt binding document in YAML format. Patch 2 add PWM fan controller driver for LGM SoC.

v7:
- Address code quality related review concerns.
- Rename fan related property to pwm-*.
- Fix one make dt_binding_check reported error.

v6:
- Readjust .apply op as per review feedback.
- Add back pwm-cells property to resolve make dt_binding_check error. pwm-cells is a required property for PWM driver.
- Add back fan related optional properties.

v5:
- Address below review concerns from Uwe Kleine-K�nig.
* Improve comments about Limitations.
* Use return value of regmap_update_bits if container function returns error code.
* Modify .apply op to have strict checking for fixed period supported by PWM HW.
* Use u64 as type when use min_t for duty_cycle.
* Add reset_control_assert() in failure case in probe where it was missing earlier.
- Remove fan specific optional properties from pwm dt binding document (Rob Herring)

v4:
- Address below review concerns from Uwe Kleine-K�nig.
* Improve notes and limitations comments.
* Add common prefixes for all #defines.
* Modify/Improve logic in .apply & .get_state ops as advised.
* Skip error messages in probe when error is -EPROBE_DEFER.
* Add dependencies in Kconfig (OF & HAS_IOMEM) and add select REGMAP_MMIO.
* Address other code quality related review concerns.
- Fix make dt_binding_check reported error in YAML file.

v3:
- Address below review concerns from Uwe Kleine-K�nig.
* Remove fan rpm calibration task from the driver.
* Modify apply op as per the review feedback.
* Add roundup & round down where necessary.
* Address other misc code quality related review concerns.
* Use devm_reset_control_get_exclusive(). (Philipp Zabel)
* Improve dt binding document.

v2:
- Address below review concerns from Uwe Kleine-K�nig.
* Add notes and limitations about PWM HW.
* Rename all functions and structure to lgm_pwm_*
* Readjust space aligninment in structure fields to single space.
* Switch to using apply instead of config/enable/disable.
* Address other code quality related concerns.
* Rebase to 5.8-rc1.
- Address review concerns in dt binding YAML from Rob Herring.

v1:
- Initial version.

Rahul Tanwar (2):
Add DT bindings YAML schema for PWM fan controller of LGM SoC Add PWM fan controller driver for LGM SoC

 .../devicetree/bindings/pwm/intel,lgm-pwm.yaml     |  54 +++++
 drivers/pwm/Kconfig                                |  11 +
 drivers/pwm/Makefile                               |   1 +
 drivers/pwm/pwm-intel-lgm.c                        | 267 +++++++++++++++++++++
 4 files changed, 333 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/intel,lgm-pwm.yaml
 create mode 100644 drivers/pwm/pwm-intel-lgm.c

2.11.0

Intel's LGM(Lightning Mountain) SoC contains a PWM fan controller which is only used to control the fan attached to the system. This PWM controller does not have any other consumer other than fan. Add DT bindings documentation for this PWM fan controller.

---
 .../devicetree/bindings/pwm/intel,lgm-pwm.yaml     | 54 ++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/intel,lgm-pwm.yaml

new file mode 100644
index 000000000000..289b82213e23
@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/intel,lgm-pwm.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: LGM SoC PWM fan controller
+
+maintainers:
+  - Rahul Tanwar <[email protected]>
+
+properties:
+  compatible:
+    const: intel,lgm-pwm
+
+  reg:
+    maxItems: 1
+
+  "#pwm-cells":
+    const: 2
+
+  clocks:
+    maxItems: 1
+
+  resets:
+    maxItems: 1
+
+  pwm-fanmode:
+    $ref: '/schemas/types.yaml#/definitions/uint32'
+    description: Specifies PWM fan mode. Default when unspecified is 2.
+
+  pwm-maxrpm:
+    $ref: '/schemas/types.yaml#/definitions/uint32'
+    description:
+      Specifies maximum RPM of PWM fan attached to the system.
+      Default when unspecified is 4000.
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - resets
+
+additionalProperties: false
+
+examples:
+  - |
+    pwm: pwm@e0d00000 {
+        compatible = "intel,lgm-pwm";
+        reg = <0xe0d00000 0x30>;
+        #pwm-cells = <2>;
+        clocks = <&cgu0 126>;
+        resets = <&rcu0 0x30 21>;
+    };

2.11.0

Intel Lightning Mountain(LGM) SoC contains a PWM fan controller. This PWM controller does not have any other consumer, it is a dedicated PWM controller for fan attached to the system. Add driver for this PWM fan controller.

---
 drivers/pwm/Kconfig         |  11 ++
 drivers/pwm/Makefile        |   1 +
 drivers/pwm/pwm-intel-lgm.c | 267 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 279 insertions(+)
 create mode 100644 drivers/pwm/pwm-intel-lgm.c

index 7dbcf6973d33..f7a832268c79 100644
@@ -232,6 +232,17 @@ config PWM_IMX_TPM
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-imx-tpm.
 
+config PWM_INTEL_LGM
+	tristate "Intel LGM PWM support"
+	depends on OF && HAS_IOMEM
+	depends on X86 || COMPILE_TEST
+	select REGMAP_MMIO
+	help
+	  Generic PWM fan controller driver for LGM SoC.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-intel-lgm.
+
 config PWM_IQS620A
 	tristate "Azoteq IQS620A PWM support"
 	depends on MFD_IQS62X || COMPILE_TEST

index 2c2ba0a03557..e9431b151694 100644
@@ -20,6 +20,7 @@ obj-$(CONFIG_PWM_IMG)		+= pwm-img.o
 obj-$(CONFIG_PWM_IMX1)		+= pwm-imx1.o
 obj-$(CONFIG_PWM_IMX27)		+= pwm-imx27.o
 obj-$(CONFIG_PWM_IMX_TPM)	+= pwm-imx-tpm.o
+obj-$(CONFIG_PWM_INTEL_LGM)	+= pwm-intel-lgm.o
 obj-$(CONFIG_PWM_IQS620A)	+= pwm-iqs620a.o
 obj-$(CONFIG_PWM_JZ4740)	+= pwm-jz4740.o
 obj-$(CONFIG_PWM_LP3943)	+= pwm-lp3943.o

2.11.0

I guess it misses the answer why pwm-fan can't be integrated into the soup?

With Best Regards,
Andy Shevchenko

Hi Andy,

Can you please elaborate more? I could not understand your point clearly.

Regards,
Rahul

It's not mine, it's Uwe's. There is an hwmon module called pwm-fan. As far as *I* understand this, it can be utilized to control fans via PWM APIs. And Uwe asked you if you considered that and why you don't integrated (coupled) it here.

With Best Regards,
Andy Shevchenko

Hi Andy,

Thanks for clarification. I now understand what Rob, Uwe & you mean by pwm-fan. I will check in detail about it if we can integrate it with pwm-fan hwmon driver.

Regards,
Rahul