Re: [PATCH v4 3/3] hwmon: Driver for Nuvoton NCT7363Y

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On Mon, Feb 26, 2024 at 04:56:06PM PST, baneric926@xxxxxxxxx wrote:
From: Ban Feng <kcfeng0@xxxxxxxxxxx>

NCT7363Y is an I2C based hardware monitoring chip from Nuvoton.

Signed-off-by: Ban Feng <kcfeng0@xxxxxxxxxxx>
---
Documentation/hwmon/index.rst   |   1 +
Documentation/hwmon/nct7363.rst |  33 +++
MAINTAINERS                     |   2 +
drivers/hwmon/Kconfig           |  11 +
drivers/hwmon/Makefile          |   1 +
drivers/hwmon/nct7363.c         | 412 ++++++++++++++++++++++++++++++++
6 files changed, 460 insertions(+)
create mode 100644 Documentation/hwmon/nct7363.rst
create mode 100644 drivers/hwmon/nct7363.c

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index c7ed1f73ac06..302f954b45be 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -165,6 +165,7 @@ Hardware Monitoring Kernel Drivers
   mp5990
   nct6683
   nct6775
+   nct7363
   nct7802
   nct7904
   npcm750-pwm-fan
diff --git a/Documentation/hwmon/nct7363.rst b/Documentation/hwmon/nct7363.rst
new file mode 100644
index 000000000000..89699c95aa4b
--- /dev/null
+++ b/Documentation/hwmon/nct7363.rst
@@ -0,0 +1,33 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver nct7363
+=====================
+
+Supported chip:
+
+  * Nuvoton NCT7363Y
+
+    Prefix: nct7363
+
+    Addresses: I2C 0x20, 0x21, 0x22, 0x23
+
+Author: Ban Feng <kcfeng0@xxxxxxxxxxx>
+
+
+Description
+-----------
+
+The NCT7363Y is a Fan controller which provides up to 16 independent
+FAN input monitors, and up to 16 independent PWM output with SMBus interface.
+
+
+Sysfs entries
+-------------
+
+Currently, the driver supports the following features:
+
+======================= =======================================================
+fanX_input		provide current fan rotation value in RPM
+
+pwmX			get or set PWM fan control value.
+======================= =======================================================
diff --git a/MAINTAINERS b/MAINTAINERS
index 7b1efefed7c4..7ca66b713e30 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15089,6 +15089,8 @@ M:	Ban Feng <kcfeng0@xxxxxxxxxxx>
L:	linux-hwmon@xxxxxxxxxxxxxxx
S:	Maintained
F:	Documentation/devicetree/bindings/hwmon/nuvoton,nct7363.yaml
+F:	Documentation/hwmon/nct7363.rst
+F:	drivers/hwmon/nct7363.c

NETDEVSIM
M:	Jakub Kicinski <kuba@xxxxxxxxxx>
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index a608264da87d..a297b5409b04 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1616,6 +1616,17 @@ config SENSORS_NCT6775_I2C
	  This driver can also be built as a module. If so, the module
	  will be called nct6775-i2c.

+config SENSORS_NCT7363
+	tristate "Nuvoton NCT7363Y"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for the Nuvoton NCT7363Y,
+	  hardware monitoring chip.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called nct7363.
+
config SENSORS_NCT7802
	tristate "Nuvoton NCT7802Y"
	depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 47be39af5c03..d5e7531204df 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -167,6 +167,7 @@ obj-$(CONFIG_SENSORS_NCT6775_CORE) += nct6775-core.o
nct6775-objs			:= nct6775-platform.o
obj-$(CONFIG_SENSORS_NCT6775)	+= nct6775.o
obj-$(CONFIG_SENSORS_NCT6775_I2C) += nct6775-i2c.o
+obj-$(CONFIG_SENSORS_NCT7363)	+= nct7363.o
obj-$(CONFIG_SENSORS_NCT7802)	+= nct7802.o
obj-$(CONFIG_SENSORS_NCT7904)	+= nct7904.o
obj-$(CONFIG_SENSORS_NPCM7XX)	+= npcm750-pwm-fan.o
diff --git a/drivers/hwmon/nct7363.c b/drivers/hwmon/nct7363.c
new file mode 100644
index 000000000000..c79d3ca4f111
--- /dev/null
+++ b/drivers/hwmon/nct7363.c
@@ -0,0 +1,412 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2023 Nuvoton Technology corporation.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#define NCT7363_REG_GPIO_0_3		0x20
+#define NCT7363_REG_GPIO_4_7		0x21
+#define NCT7363_REG_GPIO_10_13		0x22
+#define NCT7363_REG_GPIO_14_17		0x23
+#define NCT7363_REG_PWMEN_0_7		0x38
+#define NCT7363_REG_PWMEN_8_15		0x39
+#define NCT7363_REG_FANINEN_0_7		0x41
+#define NCT7363_REG_FANINEN_8_15	0x42
+#define NCT7363_REG_FANINX_HVAL(x)	(0x48 + ((x) * 2))
+#define NCT7363_REG_FANINX_LVAL(x)	(0x49 + ((x) * 2))
+#define NCT7363_REG_FSCPXDUTY(x)	(0x90 + ((x) * 2))
+
+#define PWM_SEL(x)			(BIT(0) << (((x) % 4) * 2))
+#define FANIN_SEL(x)			(BIT(1) << (((x) % 4) * 2))
+
+#define NCT7363_FANINX_LVAL_MASK	GENMASK(4, 0)
+#define NCT7363_FANIN_MASK		GENMASK(12, 0)
+
+#define NCT7363_PWM_COUNT		16
+
+static inline unsigned long FAN_FROM_REG(u16 val)
+{
+	/* In case fan is stopped or divide by 0 */
+	if (val == NCT7363_FANIN_MASK || val == 0)
+		return	0;
+
+	return (1350000UL / val);
+}
+
+static const struct of_device_id nct7363_of_match[] = {
+	{ .compatible = "nuvoton,nct7363" },

As far as I can see from the code in this driver, it looks like this driver should also be compatible with the nct7362; shall we add the ID table entry for it now? (Though I only have a datasheet for the nct7362, not the nct7363, so I don't know exactly how they differ.)

+	{ },
+};
+MODULE_DEVICE_TABLE(of, nct7363_of_match);
+
+struct nct7363_data {
+	struct regmap		*regmap;
+	struct mutex		lock; /* protect register access */
+
+	u16			fanin_mask;
+	u16			pwm_mask;
+};
+
+static int nct7363_read_fan(struct device *dev, u32 attr, int channel,
+			    long *val)
+{
+	struct nct7363_data *data = dev_get_drvdata(dev);
+	unsigned int hi, lo;
+	u16 cnt, rpm;
+	int ret = 0;
+
+	switch (attr) {
+	case hwmon_fan_input:
+		/*
+		 * High-byte register should be read first to latch
+		 * synchronous low-byte value
+		 */
+		ret = regmap_read(data->regmap,
+				  NCT7363_REG_FANINX_HVAL(channel), &hi);
+		if (ret)
+			return ret;
+
+		ret = regmap_read(data->regmap,
+			NCT7363_REG_FANINX_LVAL(channel), &lo);
+		if (ret)
+			return ret;

I think this pair of reads should be done under data->lock to ensure that the LVAL read gets the right latched value in a scenario where multiple threads executing this function end up with their register reads interleaved.

+
+		cnt = (hi << 5) | (lo & NCT7363_FANINX_LVAL_MASK);
+		rpm = FAN_FROM_REG(cnt);
+		*val = (long)rpm;

Given that rpm is assigned from an unsigned long (FAN_FROM_REG()) and then to a long (*val), is there any reason we want it as a u16 in between the two? Or for that matter, why not just:

  *val = FAN_FROM_REG(cnt);

?

+		return 0;
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static umode_t nct7363_fan_is_visible(const void *_data, u32 attr, int channel)
+{
+	const struct nct7363_data *data = _data;
+
+	switch (attr) {
+	case hwmon_fan_input:
+		if (data->fanin_mask & BIT(channel))
+			return 0444;
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static int nct7363_read_pwm(struct device *dev, u32 attr, int channel,
+			    long *val)
+{
+	struct nct7363_data *data = dev_get_drvdata(dev);
+	unsigned int regval;
+	u16 ret;
+
+	switch (attr) {
+	case hwmon_pwm_input:
+		ret = regmap_read(data->regmap,
+				  NCT7363_REG_FSCPXDUTY(channel), &regval);
+		if (ret)
+			return ret;
+
+		*val = (long)regval;
+		return 0;
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int nct7363_write_pwm(struct device *dev, u32 attr, int channel,
+			     long val)
+{
+	struct nct7363_data *data = dev_get_drvdata(dev);
+	int ret;
+
+	switch (attr) {
+	case hwmon_pwm_input:
+		if (val < 0 || val > 255)
+			return -EINVAL;
+
+		mutex_lock(&data->lock);
+		ret = regmap_write(data->regmap,
+				   NCT7363_REG_FSCPXDUTY(channel), val);
+		mutex_unlock(&data->lock);

...though here, I'm not sure the locking is needed -- is there something that necessitates it for a single register write?

+
+		return ret;
+
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static umode_t nct7363_pwm_is_visible(const void *_data, u32 attr, int channel)
+{
+	const struct nct7363_data *data = _data;
+
+	switch (attr) {
+	case hwmon_pwm_input:
+		if (data->pwm_mask & BIT(channel))
+			return 0644;
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static int nct7363_read(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long *val)
+{
+	switch (type) {
+	case hwmon_fan:
+		return nct7363_read_fan(dev, attr, channel, val);
+	case hwmon_pwm:
+		return nct7363_read_pwm(dev, attr, channel, val);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int nct7363_write(struct device *dev, enum hwmon_sensor_types type,
+			 u32 attr, int channel, long val)
+{
+	switch (type) {
+	case hwmon_pwm:
+		return nct7363_write_pwm(dev, attr, channel, val);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static umode_t nct7363_is_visible(const void *data,
+				  enum hwmon_sensor_types type,
+				  u32 attr, int channel)
+{
+	switch (type) {
+	case hwmon_fan:
+		return nct7363_fan_is_visible(data, attr, channel);
+	case hwmon_pwm:
+		return nct7363_pwm_is_visible(data, attr, channel);
+	default:
+		return 0;
+	}
+}
+
+static const struct hwmon_channel_info *nct7363_info[] = {
+	HWMON_CHANNEL_INFO(fan,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT),
+	HWMON_CHANNEL_INFO(pwm,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT),
+	NULL
+};
+
+static const struct hwmon_ops nct7363_hwmon_ops = {
+	.is_visible = nct7363_is_visible,
+	.read = nct7363_read,
+	.write = nct7363_write,
+};
+
+static const struct hwmon_chip_info nct7363_chip_info = {
+	.ops = &nct7363_hwmon_ops,
+	.info = nct7363_info,
+};
+
+static int nct7363_init_chip(struct nct7363_data *data)
+{
+	u8 i, gpio0_3 = 0, gpio4_7 = 0, gpio10_13 = 0, gpio14_17 = 0;
+	int ret;
+
+	for (i = 0; i < NCT7363_PWM_COUNT; i++) {
+		if (i < 4) {
+			if (data->pwm_mask & BIT(i))
+				gpio0_3 |= PWM_SEL(i);
+			if (data->fanin_mask & BIT(i))
+				gpio10_13 |= FANIN_SEL(i);
+		} else if (i < 8) {
+			if (data->pwm_mask & BIT(i))
+				gpio4_7 |= PWM_SEL(i);
+			if (data->fanin_mask & BIT(i))
+				gpio14_17 |= FANIN_SEL(i);
+		} else if (i < 12) {
+			if (data->pwm_mask & BIT(i))
+				gpio10_13 |= PWM_SEL(i);
+			if (data->fanin_mask & BIT(i))
+				gpio0_3 |= FANIN_SEL(i);
+		} else {
+			if (data->pwm_mask & BIT(i))
+				gpio14_17 |= PWM_SEL(i);
+			if (data->fanin_mask & BIT(i))
+				gpio4_7 |= FANIN_SEL(i);
+		}
+	}

With the caveat that I haven't actually sketched it out myself to be sure, might it be a bit cleaner to do this with a 4-element array indexed by 'i / 4' instead of a big if/else chain and a bunch of near-duplicated blocks?

+
+	/* Pin Function Configuration */
+	ret = regmap_write(data->regmap, NCT7363_REG_GPIO_0_3, gpio0_3);
+	if (ret < 0)
+		return ret;
+	ret = regmap_write(data->regmap, NCT7363_REG_GPIO_4_7, gpio4_7);
+	if (ret < 0)
+		return ret;
+	ret = regmap_write(data->regmap, NCT7363_REG_GPIO_10_13, gpio10_13);
+	if (ret < 0)
+		return ret;
+	ret = regmap_write(data->regmap, NCT7363_REG_GPIO_14_17, gpio14_17);
+	if (ret < 0)
+		return ret;
+
+	/* PWM and FANIN Monitoring Enable */
+	ret = regmap_write(data->regmap, NCT7363_REG_PWMEN_0_7,
+			   data->pwm_mask & 0xff);
+	if (ret < 0)
+		return ret;
+	ret = regmap_write(data->regmap, NCT7363_REG_PWMEN_8_15,
+			   (data->pwm_mask >> 8) & 0xff);
+	if (ret < 0)
+		return ret;
+	ret = regmap_write(data->regmap, NCT7363_REG_FANINEN_0_7,
+			   data->fanin_mask & 0xff);
+	if (ret < 0)
+		return ret;
+	ret = regmap_write(data->regmap, NCT7363_REG_FANINEN_8_15,
+			   (data->fanin_mask >> 8) & 0xff);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int nct7363_present_pwm_fanin(struct device *dev,
+				     struct device_node *child,
+				     struct nct7363_data *data)
+{
+	struct of_phandle_args args;
+	int ret, fanin_cnt;
+	u8 *fanin_ch;
+	u8 ch, index;
+
+	ret = of_parse_phandle_with_args(child, "pwms", "#pwm-cells",
+					 0, &args);
+	if (ret)
+		return ret;
+
+	data->pwm_mask |= BIT(args.args[0]);

Perhaps we should have

  if (args.args[0] >= NCT7363_PWM_COUNT)
    return -EINVAL;

here?

+
+	fanin_cnt = of_property_count_u8_elems(child, "tach-ch");
+	if (fanin_cnt < 1)

fanin_cnt < 1 || fanin_cnt >= NCT7363_PWM_COUNT

+		return -EINVAL;
+
+	fanin_ch = devm_kcalloc(dev, fanin_cnt, sizeof(*fanin_ch), GFP_KERNEL);

Keeping this allocation around persistently for the whole lifetime of the device seems unnecessary -- it's not used beyond this function, right? In fact, dynamically allocating it at all seems like overkill, considering that in addition to being temporary, it's also got a pretty small upper bound on its size. I'd think a simple

  u8 fanin_ch[NCT7363_PWM_COUNT];

would suffice? (Along with the check above to ensure fanin_cnt is within range of course.)

+	if (!fanin_ch)
+		return -ENOMEM;
+
+	ret = of_property_read_u8_array(child, "tach-ch", fanin_ch, fanin_cnt);
+	if (ret)
+		return ret;
+
+	for (ch = 0; ch < fanin_cnt; ch++) {
+		index = fanin_ch[ch];

...and likewise a range check here too?

+		data->fanin_mask |= BIT(index);
+	}
+

Should we also grab the pulses-per-revolution property here and factor that in in FAN_FROM_REG()?

+	return 0;
+}
+
+static const struct regmap_config nct7363_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static int nct7363_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct device_node *child;
+	struct nct7363_data *data;
+	struct device *hwmon_dev;
+	int ret;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->regmap = devm_regmap_init_i2c(client, &nct7363_regmap_config);
+	if (IS_ERR(data->regmap))
+		return PTR_ERR(data->regmap);
+
+	mutex_init(&data->lock);
+
+	for_each_child_of_node(dev->of_node, child) {
+		ret = nct7363_present_pwm_fanin(dev, child, data);
+		if (ret) {
+			of_node_put(child);
+			return ret;
+		}
+	}
+
+	/* Initialize the chip */
+	ret = nct7363_init_chip(data);
+	if (ret)
+		return ret;
+
+	hwmon_dev =
+		devm_hwmon_device_register_with_info(dev, client->name, data,
+						     &nct7363_chip_info, NULL);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static struct i2c_driver nct7363_driver = {
+	.class = I2C_CLASS_HWMON,

Maybe add an i2c_device_id table to accompany the of_match table?

+	.driver = {
+		.name = "nct7363",
+		.of_match_table = nct7363_of_match,
+	},
+	.probe = nct7363_probe,
+};
+
+module_i2c_driver(nct7363_driver);
+
+MODULE_AUTHOR("CW Ho <cwho@xxxxxxxxxxx>");
+MODULE_AUTHOR("Ban Feng <kcfeng0@xxxxxxxxxxx>");
+MODULE_DESCRIPTION("NCT7363 Hardware Monitoring Driver");
+MODULE_LICENSE("GPL");
--
2.34.1






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