[PATCH v3 0/4] hwmon: add lan9668 driver

[PATCH v3 0/4] hwmon: add lan9668 driver

[Michael Walle]

Add a temperature and fan controller driver for the Microchip LAN9668 SoC.

The temperature sensor uses a polynomial to calculate the actual
temperature. Fortunately, the bt1-pvt already has such a calculation.
It seems that the LAN9668 uses the same Analog Bits sensor as the
BT1 although with a different characteristic. To be able to reuse the
code move it to lib/ as it seems pretty generic to calculate any
polynomial using integers only, which might also be used by other parts
of the kernel. Another option might be to move the code to hwmon-poly.c,
I'm not sure. Thoughts?

I also plan on submitting patches to add temperature sensor support for
the GPYxxx and LAN8814 PHYs which also use polynomial_calc().

The last two patches adds the actual driver and the dt-binding for it.

changes since v2:
 - strip unwanted copy pasta.. oops
 - use "select REGMAP" instead of "depends on"

changes since v1:
 - add doc string to polynomial_calc(), moved the comment
   into the function.
 - add missing "select POLYNOMIAL" to the bt1_pvt driver
   Kconfig symbol
 - add hwmon driver documentation
 - cache sys_clk rate during probe
 - add missing ERR_CAST()
 - adapted comment for the PPS->RPM calculation
 - add temporary variable in lan966x_hwmon_read_pwm_freq()

Michael Walle (4):
  lib: add generic polynomial calculation
  hwmon: (bt1-pvt) use generic polynomial functions
  dt-bindings: hwmon: add Microchip LAN966x bindings
  hwmon: add driver for the Microchip LAN966x SoC

 .../bindings/hwmon/microchip,lan966x.yaml     |  53 +++
 Documentation/hwmon/lan966x.rst               |  40 ++
 drivers/hwmon/Kconfig                         |  13 +
 drivers/hwmon/Makefile                        |   1 +
 drivers/hwmon/bt1-pvt.c                       |  50 +--
 drivers/hwmon/lan966x-hwmon.c                 | 390 ++++++++++++++++++
 include/linux/polynomial.h                    |  35 ++
 lib/Kconfig                                   |   3 +
 lib/Makefile                                  |   2 +
 lib/polynomial.c                              | 108 +++++
 10 files changed, 658 insertions(+), 37 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/hwmon/microchip,lan966x.yaml
 create mode 100644 Documentation/hwmon/lan966x.rst
 create mode 100644 drivers/hwmon/lan966x-hwmon.c
 create mode 100644 include/linux/polynomial.h
 create mode 100644 lib/polynomial.c

-- 
2.30.2

[PATCH v3 1/4] lib: add generic polynomial calculation

[Michael Walle]

Some temperature and voltage sensors use a polynomial to convert between
raw data points and actual temperature or voltage. The polynomial is
usually the result of a curve fitting of the diode characteristic.

The BT1 PVT hwmon driver already uses such a polynonmial calculation
which is rather generic. Move it to lib/ so other drivers can reuse it.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
---
 include/linux/polynomial.h |  35 ++++++++++++
 lib/Kconfig                |   3 ++
 lib/Makefile               |   2 +
 lib/polynomial.c           | 108 +++++++++++++++++++++++++++++++++++++
 4 files changed, 148 insertions(+)
 create mode 100644 include/linux/polynomial.h
 create mode 100644 lib/polynomial.c

diff --git a/include/linux/polynomial.h b/include/linux/polynomial.h
new file mode 100644
index 000000000000..9e074a0bb6fa
--- /dev/null
+++ b/include/linux/polynomial.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
+ */
+
+#ifndef _POLYNOMIAL_H
+#define _POLYNOMIAL_H
+
+/*
+ * struct polynomial_term - one term descriptor of a polynomial
+ * @deg: degree of the term.
+ * @coef: multiplication factor of the term.
+ * @divider: distributed divider per each degree.
+ * @divider_leftover: divider leftover, which couldn't be redistributed.
+ */
+struct polynomial_term {
+	unsigned int deg;
+	long coef;
+	long divider;
+	long divider_leftover;
+};
+
+/*
+ * struct polynomial - a polynomial descriptor
+ * @total_divider: total data divider.
+ * @terms: polynomial terms, last term must have degree of 0
+ */
+struct polynomial {
+	long total_divider;
+	struct polynomial_term terms[];
+};
+
+long polynomial_calc(const struct polynomial *poly, long data);
+
+#endif
diff --git a/lib/Kconfig b/lib/Kconfig
index 087e06b4cdfd..6a843639814f 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -737,3 +737,6 @@ config PLDMFW
 
 config ASN1_ENCODER
        tristate
+
+config POLYNOMIAL
+       tristate
diff --git a/lib/Makefile b/lib/Makefile
index 6b9ffc1bd1ee..89fcae891361 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -263,6 +263,8 @@ obj-$(CONFIG_MEMREGION) += memregion.o
 obj-$(CONFIG_STMP_DEVICE) += stmp_device.o
 obj-$(CONFIG_IRQ_POLL) += irq_poll.o
 
+obj-$(CONFIG_POLYNOMIAL) += polynomial.o
+
 # stackdepot.c should not be instrumented or call instrumented functions.
 # Prevent the compiler from calling builtins like memcmp() or bcmp() from this
 # file.
diff --git a/lib/polynomial.c b/lib/polynomial.c
new file mode 100644
index 000000000000..66d383445fec
--- /dev/null
+++ b/lib/polynomial.c
@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Generic polynomial calculation using integer coefficients.
+ *
+ * Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
+ *
+ * Authors:
+ *   Maxim Kaurkin <maxim.kaurkin@baikalelectronics.ru>
+ *   Serge Semin <Sergey.Semin@baikalelectronics.ru>
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/polynomial.h>
+
+/*
+ * Originally this was part of drivers/hwmon/bt1-pvt.c.
+ * There the following conversion is used and should serve as an example here:
+ *
+ * The original translation formulae of the temperature (in degrees of Celsius)
+ * to PVT data and vice-versa are following:
+ *
+ * N = 1.8322e-8*(T^4) + 2.343e-5*(T^3) + 8.7018e-3*(T^2) + 3.9269*(T^1) +
+ *     1.7204e2
+ * T = -1.6743e-11*(N^4) + 8.1542e-8*(N^3) + -1.8201e-4*(N^2) +
+ *     3.1020e-1*(N^1) - 4.838e1
+ *
+ * where T = [-48.380, 147.438]C and N = [0, 1023].
+ *
+ * They must be accordingly altered to be suitable for the integer arithmetics.
+ * The technique is called 'factor redistribution', which just makes sure the
+ * multiplications and divisions are made so to have a result of the operations
+ * within the integer numbers limit. In addition we need to translate the
+ * formulae to accept millidegrees of Celsius. Here what they look like after
+ * the alterations:
+ *
+ * N = (18322e-20*(T^4) + 2343e-13*(T^3) + 87018e-9*(T^2) + 39269e-3*T +
+ *     17204e2) / 1e4
+ * T = -16743e-12*(D^4) + 81542e-9*(D^3) - 182010e-6*(D^2) + 310200e-3*D -
+ *     48380
+ * where T = [-48380, 147438] mC and N = [0, 1023].
+ *
+ * static const struct polynomial poly_temp_to_N = {
+ *         .total_divider = 10000,
+ *         .terms = {
+ *                 {4, 18322, 10000, 10000},
+ *                 {3, 2343, 10000, 10},
+ *                 {2, 87018, 10000, 10},
+ *                 {1, 39269, 1000, 1},
+ *                 {0, 1720400, 1, 1}
+ *         }
+ * };
+ *
+ * static const struct polynomial poly_N_to_temp = {
+ *         .total_divider = 1,
+ *         .terms = {
+ *                 {4, -16743, 1000, 1},
+ *                 {3, 81542, 1000, 1},
+ *                 {2, -182010, 1000, 1},
+ *                 {1, 310200, 1000, 1},
+ *                 {0, -48380, 1, 1}
+ *         }
+ * };
+ */
+
+/**
+ * polynomial_calc - calculate a polynomial using integer arithmetic
+ *
+ * @poly: pointer to the descriptor of the polynomial
+ * @data: input value of the polynimal
+ *
+ * Calculate the result of a polynomial using only integer arithmetic. For
+ * this to work without too much loss of precision the coefficients has to
+ * be altered. This is called factor redistribution.
+ *
+ * Returns the result of the polynomial calculation.
+ */
+long polynomial_calc(const struct polynomial *poly, long data)
+{
+	const struct polynomial_term *term = poly->terms;
+	long total_divider = poly->total_divider ?: 1;
+	long tmp, ret = 0;
+	int deg;
+
+	/*
+	 * Here is the polynomial calculation function, which performs the
+	 * redistributed terms calculations. It's pretty straightforward.
+	 * We walk over each degree term up to the free one, and perform
+	 * the redistributed multiplication of the term coefficient, its
+	 * divider (as for the rationale fraction representation), data
+	 * power and the rational fraction divider leftover. Then all of
+	 * this is collected in a total sum variable, which value is
+	 * normalized by the total divider before being returned.
+	 */
+	do {
+		tmp = term->coef;
+		for (deg = 0; deg < term->deg; ++deg)
+			tmp = mult_frac(tmp, data, term->divider);
+		ret += tmp / term->divider_leftover;
+	} while ((term++)->deg);
+
+	return ret / total_divider;
+}
+EXPORT_SYMBOL_GPL(polynomial_calc);
+
+MODULE_DESCRIPTION("Generic polynomial calculations");
+MODULE_LICENSE("GPL");
-- 
2.30.2

[PATCH v3 2/4] hwmon: (bt1-pvt) use generic polynomial functions

[Michael Walle]

The polynomial calculation function was moved into lib/ to be able to
reuse it. Move over to this one.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/Kconfig   |  1 +
 drivers/hwmon/bt1-pvt.c | 50 +++++++++++------------------------------
 2 files changed, 14 insertions(+), 37 deletions(-)

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 68a8a27ab3b7..be9773270e53 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -415,6 +415,7 @@ config SENSORS_ATXP1
 config SENSORS_BT1_PVT
 	tristate "Baikal-T1 Process, Voltage, Temperature sensor driver"
 	depends on MIPS_BAIKAL_T1 || COMPILE_TEST
+	select POLYNOMIAL
 	help
 	  If you say yes here you get support for Baikal-T1 PVT sensor
 	  embedded into the SoC.
diff --git a/drivers/hwmon/bt1-pvt.c b/drivers/hwmon/bt1-pvt.c
index 74ce5211eb75..21ab172774ec 100644
--- a/drivers/hwmon/bt1-pvt.c
+++ b/drivers/hwmon/bt1-pvt.c
@@ -26,6 +26,7 @@
 #include <linux/mutex.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
+#include <linux/polynomial.h>
 #include <linux/seqlock.h>
 #include <linux/sysfs.h>
 #include <linux/types.h>
@@ -65,7 +66,7 @@ static const struct pvt_sensor_info pvt_info[] = {
  *     48380,
  * where T = [-48380, 147438] mC and N = [0, 1023].
  */
-static const struct pvt_poly __maybe_unused poly_temp_to_N = {
+static const struct polynomial __maybe_unused poly_temp_to_N = {
 	.total_divider = 10000,
 	.terms = {
 		{4, 18322, 10000, 10000},
@@ -76,7 +77,7 @@ static const struct pvt_poly __maybe_unused poly_temp_to_N = {
 	}
 };
 
-static const struct pvt_poly poly_N_to_temp = {
+static const struct polynomial poly_N_to_temp = {
 	.total_divider = 1,
 	.terms = {
 		{4, -16743, 1000, 1},
@@ -97,7 +98,7 @@ static const struct pvt_poly poly_N_to_temp = {
  * N = (18658e-3*V - 11572) / 10,
  * V = N * 10^5 / 18658 + 11572 * 10^4 / 18658.
  */
-static const struct pvt_poly __maybe_unused poly_volt_to_N = {
+static const struct polynomial __maybe_unused poly_volt_to_N = {
 	.total_divider = 10,
 	.terms = {
 		{1, 18658, 1000, 1},
@@ -105,7 +106,7 @@ static const struct pvt_poly __maybe_unused poly_volt_to_N = {
 	}
 };
 
-static const struct pvt_poly poly_N_to_volt = {
+static const struct polynomial poly_N_to_volt = {
 	.total_divider = 10,
 	.terms = {
 		{1, 100000, 18658, 1},
@@ -113,31 +114,6 @@ static const struct pvt_poly poly_N_to_volt = {
 	}
 };
 
-/*
- * Here is the polynomial calculation function, which performs the
- * redistributed terms calculations. It's pretty straightforward. We walk
- * over each degree term up to the free one, and perform the redistributed
- * multiplication of the term coefficient, its divider (as for the rationale
- * fraction representation), data power and the rational fraction divider
- * leftover. Then all of this is collected in a total sum variable, which
- * value is normalized by the total divider before being returned.
- */
-static long pvt_calc_poly(const struct pvt_poly *poly, long data)
-{
-	const struct pvt_poly_term *term = poly->terms;
-	long tmp, ret = 0;
-	int deg;
-
-	do {
-		tmp = term->coef;
-		for (deg = 0; deg < term->deg; ++deg)
-			tmp = mult_frac(tmp, data, term->divider);
-		ret += tmp / term->divider_leftover;
-	} while ((term++)->deg);
-
-	return ret / poly->total_divider;
-}
-
 static inline u32 pvt_update(void __iomem *reg, u32 mask, u32 data)
 {
 	u32 old;
@@ -324,9 +300,9 @@ static int pvt_read_data(struct pvt_hwmon *pvt, enum pvt_sensor_type type,
 	} while (read_seqretry(&cache->data_seqlock, seq));
 
 	if (type == PVT_TEMP)
-		*val = pvt_calc_poly(&poly_N_to_temp, data);
+		*val = polynomial_calc(&poly_N_to_temp, data);
 	else
-		*val = pvt_calc_poly(&poly_N_to_volt, data);
+		*val = polynomial_calc(&poly_N_to_volt, data);
 
 	return 0;
 }
@@ -345,9 +321,9 @@ static int pvt_read_limit(struct pvt_hwmon *pvt, enum pvt_sensor_type type,
 		data = FIELD_GET(PVT_THRES_HI_MASK, data);
 
 	if (type == PVT_TEMP)
-		*val = pvt_calc_poly(&poly_N_to_temp, data);
+		*val = polynomial_calc(&poly_N_to_temp, data);
 	else
-		*val = pvt_calc_poly(&poly_N_to_volt, data);
+		*val = polynomial_calc(&poly_N_to_volt, data);
 
 	return 0;
 }
@@ -360,10 +336,10 @@ static int pvt_write_limit(struct pvt_hwmon *pvt, enum pvt_sensor_type type,
 
 	if (type == PVT_TEMP) {
 		val = clamp(val, PVT_TEMP_MIN, PVT_TEMP_MAX);
-		data = pvt_calc_poly(&poly_temp_to_N, val);
+		data = polynomial_calc(&poly_temp_to_N, val);
 	} else {
 		val = clamp(val, PVT_VOLT_MIN, PVT_VOLT_MAX);
-		data = pvt_calc_poly(&poly_volt_to_N, val);
+		data = polynomial_calc(&poly_volt_to_N, val);
 	}
 
 	/* Serialize limit update, since a part of the register is changed. */
@@ -522,9 +498,9 @@ static int pvt_read_data(struct pvt_hwmon *pvt, enum pvt_sensor_type type,
 		return -ETIMEDOUT;
 
 	if (type == PVT_TEMP)
-		*val = pvt_calc_poly(&poly_N_to_temp, data);
+		*val = polynomial_calc(&poly_N_to_temp, data);
 	else
-		*val = pvt_calc_poly(&poly_N_to_volt, data);
+		*val = polynomial_calc(&poly_N_to_volt, data);
 
 	return 0;
 }
-- 
2.30.2

[PATCH v3 3/4] dt-bindings: hwmon: add Microchip LAN966x bindings

[Michael Walle]

Add a binding for the temperature sensor and the fan controller on the
Microchip LAN966x family.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
---
 .../bindings/hwmon/microchip,lan966x.yaml     | 53 +++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/microchip,lan966x.yaml

diff --git a/Documentation/devicetree/bindings/hwmon/microchip,lan966x.yaml b/Documentation/devicetree/bindings/hwmon/microchip,lan966x.yaml
new file mode 100644
index 000000000000..390dd6755ff5
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/microchip,lan966x.yaml
@@ -0,0 +1,53 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwmon/microchip,lan966x.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip LAN966x Hardware Monitor
+
+maintainers:
+  - Michael Walle <michael@walle.cc>
+
+description: |
+  Microchip LAN966x temperature monitor and fan controller
+
+properties:
+  compatible:
+    enum:
+      - microchip,lan9668-hwmon
+
+  reg:
+    items:
+      - description: PVT registers
+      - description: FAN registers
+
+  reg-names:
+    items:
+      - const: pvt
+      - const: fan
+
+  clocks:
+    maxItems: 1
+
+  '#thermal-sensor-cells':
+    const: 0
+
+required:
+  - compatible
+  - reg
+  - reg-names
+  - clocks
+
+additionalProperties: false
+
+examples:
+  - |
+    hwmon: hwmon@e2010180 {
+        compatible = "microchip,lan9668-hwmon";
+        reg = <0xe2010180 0xc>,
+              <0xe20042a8 0xc>;
+        reg-names = "pvt", "fan";
+        clocks = <&sys_clk>;
+        #thermal-sensor-cells = <0>;
+    };
-- 
2.30.2

[PATCH v3 4/4] hwmon: add driver for the Microchip LAN966x SoC

[Michael Walle]

Add support for the temperatur sensor and the fan controller on the
Microchip LAN966x SoC. Apparently, an Analog Bits PVT sensor is used
which can measure temperature and process voltages. But only a forumlae
for the temperature sensor is known. Additionally, the SoC support a fan
tacho input as well as a PWM signal to control the fan.

Signed-off-by: Michael Walle <michael@walle.cc>
---
Just in case someone is curious why the I state the datasheet is wrong
on the PWM frequency: The actual PWM frequency was verified by measuring
the output with an oscilloscope. Also you can write a '0' as the PWM
frequency which would result in div-by-zero; but what happens is that
the output frequency will be half the frequency of a setting of '1'.

 Documentation/hwmon/lan966x.rst |  40 ++++
 drivers/hwmon/Kconfig           |  12 +
 drivers/hwmon/Makefile          |   1 +
 drivers/hwmon/lan966x-hwmon.c   | 390 ++++++++++++++++++++++++++++++++
 4 files changed, 443 insertions(+)
 create mode 100644 Documentation/hwmon/lan966x.rst
 create mode 100644 drivers/hwmon/lan966x-hwmon.c

diff --git a/Documentation/hwmon/lan966x.rst b/Documentation/hwmon/lan966x.rst
new file mode 100644
index 000000000000..1d1724afa5d2
--- /dev/null
+++ b/Documentation/hwmon/lan966x.rst
@@ -0,0 +1,40 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver lan966x-hwmon
+===========================
+
+Supported chips:
+
+  * Microchip LAN9668 (sensor in SoC)
+
+    Prefix: 'lan9668-hwmon'
+
+    Datasheet: https://microchip-ung.github.io/lan9668_reginfo
+
+Authors:
+
+	Michael Walle <michael@walle.cc>
+
+Description
+-----------
+
+This driver implements support for the Microchip LAN9668 on-chip
+temperature sensor as well as its fan controller. It provides one
+temperature sensor and one fan controller. The temperature range
+of the sensor is specified from -40 to +125 degrees Celsius and
+its accuracy is +/- 5 degrees Celsius. The fan controller has a
+tacho input and a PWM output with a customizable PWM output
+frequency ranging from ~20Hz to ~650kHz.
+
+No alarms are supported by the SoC.
+
+The driver exports temperature values, fan tacho input and PWM
+settings via the following sysfs files:
+
+**temp1_input**
+
+**fan1_input**
+
+**pwm1**
+
+**pwm1_freq**
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index be9773270e53..052b37b78919 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -815,6 +815,18 @@ config SENSORS_POWR1220
 	  This driver can also be built as a module. If so, the module
 	  will be called powr1220.
 
+config SENSORS_LAN966X
+	tristate "Microchip LAN966x Hardware Monitoring"
+	depends on SOC_LAN966 || COMPILE_TEST
+	select REGMAP
+	select POLYNOMIAL
+	help
+	  If you say yes here you get support for temperature monitoring
+	  on the Microchip LAN966x SoC.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called lan966x-hwmon.
+
 config SENSORS_LINEAGE
 	tristate "Lineage Compact Power Line Power Entry Module"
 	depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 8a03289e2aa4..51ca6956f8b7 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -100,6 +100,7 @@ obj-$(CONFIG_SENSORS_IT87)	+= it87.o
 obj-$(CONFIG_SENSORS_JC42)	+= jc42.o
 obj-$(CONFIG_SENSORS_K8TEMP)	+= k8temp.o
 obj-$(CONFIG_SENSORS_K10TEMP)	+= k10temp.o
+obj-$(CONFIG_SENSORS_LAN966X)	+= lan966x-hwmon.o
 obj-$(CONFIG_SENSORS_LINEAGE)	+= lineage-pem.o
 obj-$(CONFIG_SENSORS_LOCHNAGAR)	+= lochnagar-hwmon.o
 obj-$(CONFIG_SENSORS_LM63)	+= lm63.o
diff --git a/drivers/hwmon/lan966x-hwmon.c b/drivers/hwmon/lan966x-hwmon.c
new file mode 100644
index 000000000000..d0db2de6c7e8
--- /dev/null
+++ b/drivers/hwmon/lan966x-hwmon.c
@@ -0,0 +1,390 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/hwmon.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/polynomial.h>
+#include <linux/regmap.h>
+
+/*
+ * The original translation formulae of the temperature (in degrees of Celsius)
+ * are as follows:
+ *
+ *   T = -3.4627e-11*(N^4) + 1.1023e-7*(N^3) + -1.9165e-4*(N^2) +
+ *       3.0604e-1*(N^1) + -5.6197e1
+ *
+ * where [-56.197, 136.402]C and N = [0, 1023].
+ *
+ * They must be accordingly altered to be suitable for the integer arithmetics.
+ * The technique is called 'factor redistribution', which just makes sure the
+ * multiplications and divisions are made so to have a result of the operations
+ * within the integer numbers limit. In addition we need to translate the
+ * formulae to accept millidegrees of Celsius. Here what it looks like after
+ * the alterations:
+ *
+ *   T = -34627e-12*(N^4) + 110230e-9*(N^3) + -191650e-6*(N^2) +
+ *       306040e-3*(N^1) + -56197
+ *
+ * where T = [-56197, 136402]mC and N = [0, 1023].
+ */
+
+static const struct polynomial poly_N_to_temp = {
+	.terms = {
+		{4,  -34627, 1000, 1},
+		{3,  110230, 1000, 1},
+		{2, -191650, 1000, 1},
+		{1,  306040, 1000, 1},
+		{0,  -56197,    1, 1}
+	}
+};
+
+#define PVT_SENSOR_CTRL		0x0 /* unused */
+#define PVT_SENSOR_CFG		0x4
+#define   SENSOR_CFG_CLK_CFG		GENMASK(27, 20)
+#define   SENSOR_CFG_TRIM_VAL		GENMASK(13, 9)
+#define   SENSOR_CFG_SAMPLE_ENA		BIT(8)
+#define   SENSOR_CFG_START_CAPTURE	BIT(7)
+#define   SENSOR_CFG_CONTINIOUS_MODE	BIT(6)
+#define   SENSOR_CFG_PSAMPLE_ENA	GENMASK(1, 0)
+#define PVT_SENSOR_STAT		0x8
+#define   SENSOR_STAT_DATA_VALID	BIT(10)
+#define   SENSOR_STAT_DATA		GENMASK(9, 0)
+
+#define FAN_CFG			0x0
+#define   FAN_CFG_DUTY_CYCLE		GENMASK(23, 16)
+#define   INV_POL			BIT(3)
+#define   GATE_ENA			BIT(2)
+#define   PWM_OPEN_COL_ENA		BIT(1)
+#define   FAN_STAT_CFG			BIT(0)
+#define FAN_PWM_FREQ		0x4
+#define   FAN_PWM_CYC_10US		GENMASK(25, 15)
+#define   FAN_PWM_FREQ_FREQ		GENMASK(14, 0)
+#define FAN_CNT			0xc
+#define   FAN_CNT_DATA			GENMASK(15, 0)
+
+struct lan966x_hwmon {
+	struct regmap *regmap_pvt;
+	struct regmap *regmap_fan;
+	struct clk *clk;
+	unsigned long clk_rate;
+};
+
+static int lan966x_hwmon_read_temp(struct device *dev, long *val)
+{
+	struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
+	unsigned int data;
+	int ret;
+
+	ret = regmap_read(hwmon->regmap_pvt, PVT_SENSOR_STAT, &data);
+	if (ret < 0)
+		return ret;
+
+	if (!(data & SENSOR_STAT_DATA_VALID))
+		return -ENODATA;
+
+	*val = polynomial_calc(&poly_N_to_temp,
+			       FIELD_GET(SENSOR_STAT_DATA, data));
+
+	return 0;
+}
+
+static int lan966x_hwmon_read_fan(struct device *dev, long *val)
+{
+	struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
+	unsigned int data;
+	int ret;
+
+	ret = regmap_read(hwmon->regmap_fan, FAN_CNT, &data);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Data is given in pulses per second. Assume two pulses
+	 * per revolution.
+	 */
+	*val = FIELD_GET(FAN_CNT_DATA, data) * 60 / 2;
+
+	return 0;
+}
+
+static int lan966x_hwmon_read_pwm(struct device *dev, long *val)
+{
+	struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
+	unsigned int data;
+	int ret;
+
+	ret = regmap_read(hwmon->regmap_fan, FAN_CFG, &data);
+	if (ret < 0)
+		return ret;
+
+	*val = FIELD_GET(FAN_CFG_DUTY_CYCLE, data);
+
+	return 0;
+}
+
+static int lan966x_hwmon_read_pwm_freq(struct device *dev, long *val)
+{
+	struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
+	unsigned long tmp;
+	unsigned int data;
+	int ret;
+
+	ret = regmap_read(hwmon->regmap_fan, FAN_PWM_FREQ, &data);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Datasheet says it is sys_clk / 256 / pwm_freq. But in reality
+	 * it is sys_clk / 256 / (pwm_freq + 1).
+	 */
+	data = FIELD_GET(FAN_PWM_FREQ_FREQ, data) + 1;
+	tmp = DIV_ROUND_CLOSEST(hwmon->clk_rate, 256);
+	*val = DIV_ROUND_CLOSEST(tmp, data);
+
+	return 0;
+}
+
+static int lan966x_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
+			      u32 attr, int channel, long *val)
+{
+
+	switch (type) {
+	case hwmon_temp:
+		return lan966x_hwmon_read_temp(dev, val);
+	case hwmon_fan:
+		return lan966x_hwmon_read_fan(dev, val);
+	case hwmon_pwm:
+		switch (attr) {
+		case hwmon_pwm_input:
+			return lan966x_hwmon_read_pwm(dev, val);
+		case hwmon_pwm_freq:
+			return lan966x_hwmon_read_pwm_freq(dev, val);
+		default:
+			return -EOPNOTSUPP;
+		}
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int lan966x_hwmon_write_pwm(struct device *dev, long val)
+{
+	struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
+
+	if (val < 0 || val > 255)
+		return -EINVAL;
+
+	return regmap_update_bits(hwmon->regmap_fan, FAN_CFG,
+				  FAN_CFG_DUTY_CYCLE,
+				  FIELD_PREP(FAN_CFG_DUTY_CYCLE, val));
+}
+
+static int lan966x_hwmon_write_pwm_freq(struct device *dev, long val)
+{
+	struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
+
+	val = DIV_ROUND_CLOSEST(hwmon->clk_rate, val);
+	val = DIV_ROUND_CLOSEST(val, 256) - 1;
+	val = clamp_val(val, 0, FAN_PWM_FREQ_FREQ);
+
+	return regmap_update_bits(hwmon->regmap_fan, FAN_PWM_FREQ,
+				  FAN_PWM_FREQ_FREQ,
+				  FIELD_PREP(FAN_PWM_FREQ_FREQ, val));
+}
+
+static int lan966x_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
+			       u32 attr, int channel, long val)
+{
+	switch (type) {
+	case hwmon_pwm:
+		switch (attr) {
+		case hwmon_pwm_input:
+			return lan966x_hwmon_write_pwm(dev, val);
+		case hwmon_pwm_freq:
+			return lan966x_hwmon_write_pwm_freq(dev, val);
+		default:
+			return -EOPNOTSUPP;
+		}
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static umode_t lan966x_hwmon_is_visible(const void *data,
+					enum hwmon_sensor_types type,
+					u32 attr, int channel)
+{
+	umode_t mode = 0;
+
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_input:
+			mode = 0444;
+			break;
+		default:
+			break;
+		}
+		break;
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_input:
+			mode = 0444;
+			break;
+		default:
+			break;
+		}
+		break;
+	case hwmon_pwm:
+		switch (attr) {
+		case hwmon_pwm_input:
+		case hwmon_pwm_freq:
+			mode = 0644;
+			break;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	return mode;
+}
+
+
+static const struct hwmon_channel_info *lan966x_hwmon_info[] = {
+	HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
+	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
+	HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
+	HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT | HWMON_PWM_FREQ),
+	NULL
+};
+
+static const struct hwmon_ops lan966x_hwmon_ops = {
+	.is_visible = lan966x_hwmon_is_visible,
+	.read = lan966x_hwmon_read,
+	.write = lan966x_hwmon_write,
+};
+
+static const struct hwmon_chip_info lan966x_hwmon_chip_info = {
+	.ops = &lan966x_hwmon_ops,
+	.info = lan966x_hwmon_info,
+};
+
+static int lan966x_hwmon_enable(struct lan966x_hwmon *hwmon)
+{
+	unsigned int mask = SENSOR_CFG_SAMPLE_ENA |
+			    SENSOR_CFG_START_CAPTURE |
+			    SENSOR_CFG_CONTINIOUS_MODE |
+			    SENSOR_CFG_PSAMPLE_ENA;
+	unsigned int val;
+
+	/* enable continuous mode */
+	val = SENSOR_CFG_SAMPLE_ENA | SENSOR_CFG_CONTINIOUS_MODE;
+
+	return regmap_update_bits(hwmon->regmap_pvt, PVT_SENSOR_CFG,
+				  mask, val);
+}
+
+static struct regmap *lan966x_init_regmap(struct platform_device *pdev,
+					  const char *name)
+{
+	struct regmap_config regmap_config = {
+		.reg_bits = 32,
+		.reg_stride = 4,
+		.val_bits = 32,
+	};
+	void __iomem *base;
+
+	base = devm_platform_ioremap_resource_byname(pdev, name);
+	if (IS_ERR(base))
+		return ERR_CAST(base);
+
+	regmap_config.name = name;
+
+	return devm_regmap_init_mmio(&pdev->dev, base, &regmap_config);
+}
+
+static void lan966x_clk_disable(void *data)
+{
+	struct lan966x_hwmon *hwmon = data;
+
+	clk_disable_unprepare(hwmon->clk);
+}
+
+static int lan966x_clk_enable(struct device *dev, struct lan966x_hwmon *hwmon)
+{
+	int ret;
+
+	ret = clk_prepare_enable(hwmon->clk);
+	if (ret)
+		return ret;
+
+	return devm_add_action_or_reset(dev, lan966x_clk_disable, hwmon);
+}
+
+static int lan966x_hwmon_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct lan966x_hwmon *hwmon;
+	struct device *hwmon_dev;
+	int ret;
+
+	hwmon = devm_kzalloc(dev, sizeof(*hwmon), GFP_KERNEL);
+	if (!hwmon)
+		return -ENOMEM;
+
+	hwmon->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(hwmon->clk))
+		return dev_err_probe(dev, PTR_ERR(hwmon->clk),
+				     "failed to get clock\n");
+
+	ret = lan966x_clk_enable(dev, hwmon);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to enable clock\n");
+
+	hwmon->clk_rate = clk_get_rate(hwmon->clk);
+
+	hwmon->regmap_pvt = lan966x_init_regmap(pdev, "pvt");
+	if (IS_ERR(hwmon->regmap_pvt))
+		return dev_err_probe(dev, PTR_ERR(hwmon->regmap_pvt),
+				     "failed to get regmap for PVT registers\n");
+
+	hwmon->regmap_fan = lan966x_init_regmap(pdev, "fan");
+	if (IS_ERR(hwmon->regmap_fan))
+		return dev_err_probe(dev, PTR_ERR(hwmon->regmap_fan),
+				     "failed to get regmap for fan registers\n");
+
+	hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
+				"lan966x_hwmon", hwmon,
+				&lan966x_hwmon_chip_info, NULL);
+	if (IS_ERR(hwmon_dev))
+		return dev_err_probe(dev, PTR_ERR(hwmon_dev),
+				     "failed to register hwmon device\n");
+
+	return lan966x_hwmon_enable(hwmon);
+}
+
+static const struct of_device_id lan966x_hwmon_of_match[] = {
+	{ .compatible = "microchip,lan9668-hwmon" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, lan966x_hwmon_of_match);
+
+static struct platform_driver lan966x_hwmon_driver = {
+	.probe = lan966x_hwmon_probe,
+	.driver = {
+		.name = "lan966x-hwmon",
+		.of_match_table = lan966x_hwmon_of_match,
+	},
+};
+module_platform_driver(lan966x_hwmon_driver);
+
+MODULE_DESCRIPTION("LAN966x Hardware Monitoring Driver");
+MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
+MODULE_LICENSE("GPL");
-- 
2.30.2

Re: [PATCH v3 4/4] hwmon: add driver for the Microchip LAN966x SoC

[Guenter Roeck]

On 3/31/22 09:24, Michael Walle wrote:
> Add support for the temperatur sensor and the fan controller on the
> Microchip LAN966x SoC. Apparently, an Analog Bits PVT sensor is used
> which can measure temperature and process voltages. But only a forumlae
> for the temperature sensor is known. Additionally, the SoC support a fan
> tacho input as well as a PWM signal to control the fan.
> 
> Signed-off-by: Michael Walle <michael@walle.cc>
> ---
> Just in case someone is curious why the I state the datasheet is wrong
> on the PWM frequency: The actual PWM frequency was verified by measuring
> the output with an oscilloscope. Also you can write a '0' as the PWM
> frequency which would result in div-by-zero; but what happens is that
> the output frequency will be half the frequency of a setting of '1'.
> 
>   Documentation/hwmon/lan966x.rst |  40 ++++
>   drivers/hwmon/Kconfig           |  12 +
>   drivers/hwmon/Makefile          |   1 +
>   drivers/hwmon/lan966x-hwmon.c   | 390 ++++++++++++++++++++++++++++++++
>   4 files changed, 443 insertions(+)
>   create mode 100644 Documentation/hwmon/lan966x.rst
>   create mode 100644 drivers/hwmon/lan966x-hwmon.c
> 
> diff --git a/Documentation/hwmon/lan966x.rst b/Documentation/hwmon/lan966x.rst
> new file mode 100644
> index 000000000000..1d1724afa5d2
> --- /dev/null
> +++ b/Documentation/hwmon/lan966x.rst
> @@ -0,0 +1,40 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +Kernel driver lan966x-hwmon
> +===========================
> +
> +Supported chips:
> +
> +  * Microchip LAN9668 (sensor in SoC)
> +
> +    Prefix: 'lan9668-hwmon'
> +
> +    Datasheet: https://microchip-ung.github.io/lan9668_reginfo
> +
> +Authors:
> +
> +	Michael Walle <michael@walle.cc>
> +
> +Description
> +-----------
> +
> +This driver implements support for the Microchip LAN9668 on-chip
> +temperature sensor as well as its fan controller. It provides one
> +temperature sensor and one fan controller. The temperature range
> +of the sensor is specified from -40 to +125 degrees Celsius and
> +its accuracy is +/- 5 degrees Celsius. The fan controller has a
> +tacho input and a PWM output with a customizable PWM output
> +frequency ranging from ~20Hz to ~650kHz.
> +
> +No alarms are supported by the SoC.
> +
> +The driver exports temperature values, fan tacho input and PWM
> +settings via the following sysfs files:
> +
> +**temp1_input**
> +
> +**fan1_input**
> +
> +**pwm1**
> +
> +**pwm1_freq**
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index be9773270e53..052b37b78919 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -815,6 +815,18 @@ config SENSORS_POWR1220
>   	  This driver can also be built as a module. If so, the module
>   	  will be called powr1220.
>   
> +config SENSORS_LAN966X
> +	tristate "Microchip LAN966x Hardware Monitoring"
> +	depends on SOC_LAN966 || COMPILE_TEST
> +	select REGMAP
> +	select POLYNOMIAL
> +	help
> +	  If you say yes here you get support for temperature monitoring
> +	  on the Microchip LAN966x SoC.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called lan966x-hwmon.
> +
>   config SENSORS_LINEAGE
>   	tristate "Lineage Compact Power Line Power Entry Module"
>   	depends on I2C
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 8a03289e2aa4..51ca6956f8b7 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -100,6 +100,7 @@ obj-$(CONFIG_SENSORS_IT87)	+= it87.o
>   obj-$(CONFIG_SENSORS_JC42)	+= jc42.o
>   obj-$(CONFIG_SENSORS_K8TEMP)	+= k8temp.o
>   obj-$(CONFIG_SENSORS_K10TEMP)	+= k10temp.o
> +obj-$(CONFIG_SENSORS_LAN966X)	+= lan966x-hwmon.o
>   obj-$(CONFIG_SENSORS_LINEAGE)	+= lineage-pem.o
>   obj-$(CONFIG_SENSORS_LOCHNAGAR)	+= lochnagar-hwmon.o
>   obj-$(CONFIG_SENSORS_LM63)	+= lm63.o
> diff --git a/drivers/hwmon/lan966x-hwmon.c b/drivers/hwmon/lan966x-hwmon.c
> new file mode 100644
> index 000000000000..d0db2de6c7e8
> --- /dev/null
> +++ b/drivers/hwmon/lan966x-hwmon.c
> @@ -0,0 +1,390 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <linux/bitfield.h>
> +#include <linux/clk.h>
> +#include <linux/hwmon.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/platform_device.h>
> +#include <linux/polynomial.h>
> +#include <linux/regmap.h>
> +
> +/*
> + * The original translation formulae of the temperature (in degrees of Celsius)
> + * are as follows:
> + *
> + *   T = -3.4627e-11*(N^4) + 1.1023e-7*(N^3) + -1.9165e-4*(N^2) +
> + *       3.0604e-1*(N^1) + -5.6197e1
> + *
> + * where [-56.197, 136.402]C and N = [0, 1023].
> + *
> + * They must be accordingly altered to be suitable for the integer arithmetics.
> + * The technique is called 'factor redistribution', which just makes sure the
> + * multiplications and divisions are made so to have a result of the operations
> + * within the integer numbers limit. In addition we need to translate the
> + * formulae to accept millidegrees of Celsius. Here what it looks like after
> + * the alterations:
> + *
> + *   T = -34627e-12*(N^4) + 110230e-9*(N^3) + -191650e-6*(N^2) +
> + *       306040e-3*(N^1) + -56197
> + *
> + * where T = [-56197, 136402]mC and N = [0, 1023].
> + */
> +
> +static const struct polynomial poly_N_to_temp = {
> +	.terms = {
> +		{4,  -34627, 1000, 1},
> +		{3,  110230, 1000, 1},
> +		{2, -191650, 1000, 1},
> +		{1,  306040, 1000, 1},
> +		{0,  -56197,    1, 1}
> +	}
> +};
> +
> +#define PVT_SENSOR_CTRL		0x0 /* unused */
> +#define PVT_SENSOR_CFG		0x4
> +#define   SENSOR_CFG_CLK_CFG		GENMASK(27, 20)
> +#define   SENSOR_CFG_TRIM_VAL		GENMASK(13, 9)
> +#define   SENSOR_CFG_SAMPLE_ENA		BIT(8)
> +#define   SENSOR_CFG_START_CAPTURE	BIT(7)
> +#define   SENSOR_CFG_CONTINIOUS_MODE	BIT(6)
> +#define   SENSOR_CFG_PSAMPLE_ENA	GENMASK(1, 0)
> +#define PVT_SENSOR_STAT		0x8
> +#define   SENSOR_STAT_DATA_VALID	BIT(10)
> +#define   SENSOR_STAT_DATA		GENMASK(9, 0)
> +
> +#define FAN_CFG			0x0
> +#define   FAN_CFG_DUTY_CYCLE		GENMASK(23, 16)
> +#define   INV_POL			BIT(3)
> +#define   GATE_ENA			BIT(2)
> +#define   PWM_OPEN_COL_ENA		BIT(1)
> +#define   FAN_STAT_CFG			BIT(0)
> +#define FAN_PWM_FREQ		0x4
> +#define   FAN_PWM_CYC_10US		GENMASK(25, 15)
> +#define   FAN_PWM_FREQ_FREQ		GENMASK(14, 0)
> +#define FAN_CNT			0xc
> +#define   FAN_CNT_DATA			GENMASK(15, 0)
> +
> +struct lan966x_hwmon {
> +	struct regmap *regmap_pvt;
> +	struct regmap *regmap_fan;
> +	struct clk *clk;
> +	unsigned long clk_rate;
> +};
> +
> +static int lan966x_hwmon_read_temp(struct device *dev, long *val)
> +{
> +	struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
> +	unsigned int data;
> +	int ret;
> +
> +	ret = regmap_read(hwmon->regmap_pvt, PVT_SENSOR_STAT, &data);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (!(data & SENSOR_STAT_DATA_VALID))
> +		return -ENODATA;
> +
> +	*val = polynomial_calc(&poly_N_to_temp,
> +			       FIELD_GET(SENSOR_STAT_DATA, data));
> +
> +	return 0;
> +}
> +
> +static int lan966x_hwmon_read_fan(struct device *dev, long *val)
> +{ > +	struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
> +	unsigned int data;
> +	int ret;
> +
> +	ret = regmap_read(hwmon->regmap_fan, FAN_CNT, &data);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * Data is given in pulses per second. Assume two pulses
> +	 * per revolution.
> +	 */
> +	*val = FIELD_GET(FAN_CNT_DATA, data) * 60 / 2;
> +
> +	return 0;
> +}
> +
> +static int lan966x_hwmon_read_pwm(struct device *dev, long *val)
> +{
> +	struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
> +	unsigned int data;
> +	int ret;
> +
> +	ret = regmap_read(hwmon->regmap_fan, FAN_CFG, &data);
> +	if (ret < 0)
> +		return ret;
> +
> +	*val = FIELD_GET(FAN_CFG_DUTY_CYCLE, data);
> +
> +	return 0;
> +}
> +
> +static int lan966x_hwmon_read_pwm_freq(struct device *dev, long *val)
> +{
> +	struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
> +	unsigned long tmp;
> +	unsigned int data;
> +	int ret;
> +
> +	ret = regmap_read(hwmon->regmap_fan, FAN_PWM_FREQ, &data);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * Datasheet says it is sys_clk / 256 / pwm_freq. But in reality
> +	 * it is sys_clk / 256 / (pwm_freq + 1).
> +	 */
> +	data = FIELD_GET(FAN_PWM_FREQ_FREQ, data) + 1;
> +	tmp = DIV_ROUND_CLOSEST(hwmon->clk_rate, 256);
> +	*val = DIV_ROUND_CLOSEST(tmp, data);
> +
> +	return 0;
> +}
> +
> +static int lan966x_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
> +			      u32 attr, int channel, long *val)
> +{
> +

Unnecessary empty line (checkpatch --strict)

> +	switch (type) {
> +	case hwmon_temp:
> +		return lan966x_hwmon_read_temp(dev, val);
> +	case hwmon_fan:
> +		return lan966x_hwmon_read_fan(dev, val);
> +	case hwmon_pwm:
> +		switch (attr) {
> +		case hwmon_pwm_input:
> +			return lan966x_hwmon_read_pwm(dev, val);
> +		case hwmon_pwm_freq:
> +			return lan966x_hwmon_read_pwm_freq(dev, val);
> +		default:
> +			return -EOPNOTSUPP;
> +		}
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int lan966x_hwmon_write_pwm(struct device *dev, long val)
> +{
> +	struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
> +
> +	if (val < 0 || val > 255)
> +		return -EINVAL;
> +
> +	return regmap_update_bits(hwmon->regmap_fan, FAN_CFG,
> +				  FAN_CFG_DUTY_CYCLE,
> +				  FIELD_PREP(FAN_CFG_DUTY_CYCLE, val));
> +}
> +
> +static int lan966x_hwmon_write_pwm_freq(struct device *dev, long val)
> +{
> +	struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
> +
> +	val = DIV_ROUND_CLOSEST(hwmon->clk_rate, val);

I must have looked at this for an hour, but I didn't see the problem.
Sorry for that. Try writing "0" as new pwm frequency.

> +	val = DIV_ROUND_CLOSEST(val, 256) - 1;
> +	val = clamp_val(val, 0, FAN_PWM_FREQ_FREQ);
> +
> +	return regmap_update_bits(hwmon->regmap_fan, FAN_PWM_FREQ,
> +				  FAN_PWM_FREQ_FREQ,
> +				  FIELD_PREP(FAN_PWM_FREQ_FREQ, val));
> +}
> +
> +static int lan966x_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
> +			       u32 attr, int channel, long val)
> +{
> +	switch (type) {
> +	case hwmon_pwm:
> +		switch (attr) {
> +		case hwmon_pwm_input:
> +			return lan966x_hwmon_write_pwm(dev, val);
> +		case hwmon_pwm_freq:
> +			return lan966x_hwmon_write_pwm_freq(dev, val);
> +		default:
> +			return -EOPNOTSUPP;
> +		}
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static umode_t lan966x_hwmon_is_visible(const void *data,
> +					enum hwmon_sensor_types type,
> +					u32 attr, int channel)
> +{
> +	umode_t mode = 0;
> +
> +	switch (type) {
> +	case hwmon_temp:
> +		switch (attr) {
> +		case hwmon_temp_input:
> +			mode = 0444;
> +			break;
> +		default:
> +			break;
> +		}
> +		break;
> +	case hwmon_fan:
> +		switch (attr) {
> +		case hwmon_fan_input:
> +			mode = 0444;
> +			break;
> +		default:
> +			break;
> +		}
> +		break;
> +	case hwmon_pwm:
> +		switch (attr) {
> +		case hwmon_pwm_input:
> +		case hwmon_pwm_freq:
> +			mode = 0644;
> +			break;
> +		default:
> +			break;
> +		}
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	return mode;
> +}
> +
> +

Extra empty line. Run checkpatch --strict to catch those.

> +static const struct hwmon_channel_info *lan966x_hwmon_info[] = {
> +	HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
> +	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
> +	HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
> +	HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT | HWMON_PWM_FREQ),
> +	NULL
> +};
> +
> +static const struct hwmon_ops lan966x_hwmon_ops = {
> +	.is_visible = lan966x_hwmon_is_visible,
> +	.read = lan966x_hwmon_read,
> +	.write = lan966x_hwmon_write,
> +};
> +
> +static const struct hwmon_chip_info lan966x_hwmon_chip_info = {
> +	.ops = &lan966x_hwmon_ops,
> +	.info = lan966x_hwmon_info,
> +};
> +
> +static int lan966x_hwmon_enable(struct lan966x_hwmon *hwmon)
> +{
> +	unsigned int mask = SENSOR_CFG_SAMPLE_ENA |
> +			    SENSOR_CFG_START_CAPTURE |
> +			    SENSOR_CFG_CONTINIOUS_MODE |
> +			    SENSOR_CFG_PSAMPLE_ENA;
> +	unsigned int val;
> +
> +	/* enable continuous mode */
> +	val = SENSOR_CFG_SAMPLE_ENA | SENSOR_CFG_CONTINIOUS_MODE;
> +

I am curious: Why not as part of the assignment, similar to 'mask' ?

> +	return regmap_update_bits(hwmon->regmap_pvt, PVT_SENSOR_CFG,
> +				  mask, val);
> +}
> +
> +static struct regmap *lan966x_init_regmap(struct platform_device *pdev,
> +					  const char *name)
> +{
> +	struct regmap_config regmap_config = {
> +		.reg_bits = 32,
> +		.reg_stride = 4,
> +		.val_bits = 32,
> +	};
> +	void __iomem *base;
> +
> +	base = devm_platform_ioremap_resource_byname(pdev, name);
> +	if (IS_ERR(base))
> +		return ERR_CAST(base);
> +
> +	regmap_config.name = name;
> +
> +	return devm_regmap_init_mmio(&pdev->dev, base, &regmap_config);
> +}
> +
> +static void lan966x_clk_disable(void *data)
> +{
> +	struct lan966x_hwmon *hwmon = data;
> +
> +	clk_disable_unprepare(hwmon->clk);
> +}
> +
> +static int lan966x_clk_enable(struct device *dev, struct lan966x_hwmon *hwmon)
> +{
> +	int ret;
> +
> +	ret = clk_prepare_enable(hwmon->clk);
> +	if (ret)
> +		return ret;
> +
> +	return devm_add_action_or_reset(dev, lan966x_clk_disable, hwmon);
> +}
> +
> +static int lan966x_hwmon_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct lan966x_hwmon *hwmon;
> +	struct device *hwmon_dev;
> +	int ret;
> +
> +	hwmon = devm_kzalloc(dev, sizeof(*hwmon), GFP_KERNEL);
> +	if (!hwmon)
> +		return -ENOMEM;
> +
> +	hwmon->clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(hwmon->clk))
> +		return dev_err_probe(dev, PTR_ERR(hwmon->clk),
> +				     "failed to get clock\n");
> +
> +	ret = lan966x_clk_enable(dev, hwmon);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to enable clock\n");
> +
> +	hwmon->clk_rate = clk_get_rate(hwmon->clk);
> +
> +	hwmon->regmap_pvt = lan966x_init_regmap(pdev, "pvt");
> +	if (IS_ERR(hwmon->regmap_pvt))
> +		return dev_err_probe(dev, PTR_ERR(hwmon->regmap_pvt),
> +				     "failed to get regmap for PVT registers\n");
> +
> +	hwmon->regmap_fan = lan966x_init_regmap(pdev, "fan");
> +	if (IS_ERR(hwmon->regmap_fan))
> +		return dev_err_probe(dev, PTR_ERR(hwmon->regmap_fan),
> +				     "failed to get regmap for fan registers\n");
> +
> +	hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
> +				"lan966x_hwmon", hwmon,
> +				&lan966x_hwmon_chip_info, NULL);
> +	if (IS_ERR(hwmon_dev))
> +		return dev_err_probe(dev, PTR_ERR(hwmon_dev),
> +				     "failed to register hwmon device\n");
> +
> +	return lan966x_hwmon_enable(hwmon);

Since I am nitpicking: It may make sense to call this function before
registering the hwmon device, and it may make sense to disable sampling
when unloading the driver (you could trigger that by calling
devm_add_action_or_reset() from lan966x_hwmon_enable).

> +}
> +
> +static const struct of_device_id lan966x_hwmon_of_match[] = {
> +	{ .compatible = "microchip,lan9668-hwmon" },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, lan966x_hwmon_of_match);
> +
> +static struct platform_driver lan966x_hwmon_driver = {
> +	.probe = lan966x_hwmon_probe,
> +	.driver = {
> +		.name = "lan966x-hwmon",
> +		.of_match_table = lan966x_hwmon_of_match,
> +	},
> +};
> +module_platform_driver(lan966x_hwmon_driver);
> +
> +MODULE_DESCRIPTION("LAN966x Hardware Monitoring Driver");
> +MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
> +MODULE_LICENSE("GPL");

Re: [PATCH v3 4/4] hwmon: add driver for the Microchip LAN966x SoC

[Michael Walle]

Am 2022-03-31 19:28, schrieb Guenter Roeck:

>> +static int lan966x_hwmon_write_pwm_freq(struct device *dev, long val)
>> +{
>> +	struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
>> +
>> +	val = DIV_ROUND_CLOSEST(hwmon->clk_rate, val);
> 
> I must have looked at this for an hour, but I didn't see the problem.
> Sorry for that. Try writing "0" as new pwm frequency.

Ohh, and negative values..

I'll add a

if (val <= 0)
     return -EINVAL;

>> +static int lan966x_hwmon_enable(struct lan966x_hwmon *hwmon)
>> +{
>> +	unsigned int mask = SENSOR_CFG_SAMPLE_ENA |
>> +			    SENSOR_CFG_START_CAPTURE |
>> +			    SENSOR_CFG_CONTINIOUS_MODE |
>> +			    SENSOR_CFG_PSAMPLE_ENA;
>> +	unsigned int val;
>> +
>> +	/* enable continuous mode */
>> +	val = SENSOR_CFG_SAMPLE_ENA | SENSOR_CFG_CONTINIOUS_MODE;
>> +
> 
> I am curious: Why not as part of the assignment, similar to 'mask' ?

There was code to set the clock divider, but I've removed
it as the hardware has a sane default. That left just that one
line, but moving the comment above the declaration looked
weird.

Now thinking about it again, it might make sense to bring
back the code to set the clock divider in case someone
will fiddle around with it before the driver is probed.

#define LAN966X_PVT_CLK 1200000 /* 1.2 MHz */

/* set PVT clock to be between 1.15 and 1.25 MHz */
div = DIV_ROUND_CLOSEST(hwmon->clk_rate, LAN966X_PVT_CLK);
val |= FIELD_PREP(SENSOR_CFG_CLK_CFG, div);

>> +static int lan966x_hwmon_probe(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct lan966x_hwmon *hwmon;
>> +	struct device *hwmon_dev;
>> +	int ret;
>> +
>> +	hwmon = devm_kzalloc(dev, sizeof(*hwmon), GFP_KERNEL);
>> +	if (!hwmon)
>> +		return -ENOMEM;
>> +
>> +	hwmon->clk = devm_clk_get(dev, NULL);
>> +	if (IS_ERR(hwmon->clk))
>> +		return dev_err_probe(dev, PTR_ERR(hwmon->clk),
>> +				     "failed to get clock\n");
>> +
>> +	ret = lan966x_clk_enable(dev, hwmon);
>> +	if (ret)
>> +		return dev_err_probe(dev, ret, "failed to enable clock\n");
>> +
>> +	hwmon->clk_rate = clk_get_rate(hwmon->clk);
>> +
>> +	hwmon->regmap_pvt = lan966x_init_regmap(pdev, "pvt");
>> +	if (IS_ERR(hwmon->regmap_pvt))
>> +		return dev_err_probe(dev, PTR_ERR(hwmon->regmap_pvt),
>> +				     "failed to get regmap for PVT registers\n");
>> +
>> +	hwmon->regmap_fan = lan966x_init_regmap(pdev, "fan");
>> +	if (IS_ERR(hwmon->regmap_fan))
>> +		return dev_err_probe(dev, PTR_ERR(hwmon->regmap_fan),
>> +				     "failed to get regmap for fan registers\n");
>> +
>> +	hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
>> +				"lan966x_hwmon", hwmon,
>> +				&lan966x_hwmon_chip_info, NULL);
>> +	if (IS_ERR(hwmon_dev))
>> +		return dev_err_probe(dev, PTR_ERR(hwmon_dev),
>> +				     "failed to register hwmon device\n");
>> +
>> +	return lan966x_hwmon_enable(hwmon);
> 
> Since I am nitpicking: It may make sense to call this function before
> registering the hwmon device, and it may make sense to disable sampling
> when unloading the driver (you could trigger that by calling
> devm_add_action_or_reset() from lan966x_hwmon_enable).

sure

-michael

Re: [PATCH v3 4/4] hwmon: add driver for the Microchip LAN966x SoC

[Guenter Roeck]

On 4/1/22 05:57, Michael Walle wrote:
> Am 2022-03-31 19:28, schrieb Guenter Roeck:
> 
>>> +static int lan966x_hwmon_write_pwm_freq(struct device *dev, long val)
>>> +{
>>> +    struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
>>> +
>>> +    val = DIV_ROUND_CLOSEST(hwmon->clk_rate, val);
>>
>> I must have looked at this for an hour, but I didn't see the problem.
>> Sorry for that. Try writing "0" as new pwm frequency.
> 
> Ohh, and negative values..
> 
> I'll add a
> 
> if (val <= 0)
>      return -EINVAL;
> 
>>> +static int lan966x_hwmon_enable(struct lan966x_hwmon *hwmon)
>>> +{
>>> +    unsigned int mask = SENSOR_CFG_SAMPLE_ENA |
>>> +                SENSOR_CFG_START_CAPTURE |
>>> +                SENSOR_CFG_CONTINIOUS_MODE |
>>> +                SENSOR_CFG_PSAMPLE_ENA;
>>> +    unsigned int val;
>>> +
>>> +    /* enable continuous mode */
>>> +    val = SENSOR_CFG_SAMPLE_ENA | SENSOR_CFG_CONTINIOUS_MODE;
>>> +
>>
>> I am curious: Why not as part of the assignment, similar to 'mask' ?
> 
> There was code to set the clock divider, but I've removed
> it as the hardware has a sane default. That left just that one
> line, but moving the comment above the declaration looked
> weird.
> 
> Now thinking about it again, it might make sense to bring
> back the code to set the clock divider in case someone
> will fiddle around with it before the driver is probed.
> 
> #define LAN966X_PVT_CLK 1200000 /* 1.2 MHz */
> 
> /* set PVT clock to be between 1.15 and 1.25 MHz */
> div = DIV_ROUND_CLOSEST(hwmon->clk_rate, LAN966X_PVT_CLK);
> val |= FIELD_PREP(SENSOR_CFG_CLK_CFG, div);
> 

Yes, that would be a good idea.

Thanks,
Guenter

>>> +static int lan966x_hwmon_probe(struct platform_device *pdev)
>>> +{
>>> +    struct device *dev = &pdev->dev;
>>> +    struct lan966x_hwmon *hwmon;
>>> +    struct device *hwmon_dev;
>>> +    int ret;
>>> +
>>> +    hwmon = devm_kzalloc(dev, sizeof(*hwmon), GFP_KERNEL);
>>> +    if (!hwmon)
>>> +        return -ENOMEM;
>>> +
>>> +    hwmon->clk = devm_clk_get(dev, NULL);
>>> +    if (IS_ERR(hwmon->clk))
>>> +        return dev_err_probe(dev, PTR_ERR(hwmon->clk),
>>> +                     "failed to get clock\n");
>>> +
>>> +    ret = lan966x_clk_enable(dev, hwmon);
>>> +    if (ret)
>>> +        return dev_err_probe(dev, ret, "failed to enable clock\n");
>>> +
>>> +    hwmon->clk_rate = clk_get_rate(hwmon->clk);
>>> +
>>> +    hwmon->regmap_pvt = lan966x_init_regmap(pdev, "pvt");
>>> +    if (IS_ERR(hwmon->regmap_pvt))
>>> +        return dev_err_probe(dev, PTR_ERR(hwmon->regmap_pvt),
>>> +                     "failed to get regmap for PVT registers\n");
>>> +
>>> +    hwmon->regmap_fan = lan966x_init_regmap(pdev, "fan");
>>> +    if (IS_ERR(hwmon->regmap_fan))
>>> +        return dev_err_probe(dev, PTR_ERR(hwmon->regmap_fan),
>>> +                     "failed to get regmap for fan registers\n");
>>> +
>>> +    hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
>>> +                "lan966x_hwmon", hwmon,
>>> +                &lan966x_hwmon_chip_info, NULL);
>>> +    if (IS_ERR(hwmon_dev))
>>> +        return dev_err_probe(dev, PTR_ERR(hwmon_dev),
>>> +                     "failed to register hwmon device\n");
>>> +
>>> +    return lan966x_hwmon_enable(hwmon);
>>
>> Since I am nitpicking: It may make sense to call this function before
>> registering the hwmon device, and it may make sense to disable sampling
>> when unloading the driver (you could trigger that by calling
>> devm_add_action_or_reset() from lan966x_hwmon_enable).
> 
> sure
> 
> -michael