diff mbox series

[3/3] hwmon: Add Aspeed ast2600 TACH support

Message ID 20221031103809.20225-4-billy_tsai@aspeedtech.com
State Superseded, archived
Headers show
Series Support pwm/tach driver for aspeed ast26xx | expand

Commit Message

Billy Tsai Oct. 31, 2022, 10:38 a.m. UTC 
This patch add the support of Tachometer which can use to monitor the
frequency of the input. The tach supports up to 16 channels and it's part
function of multi-function device "pwm-tach controller".

Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com>
---
 drivers/hwmon/Kconfig               |   9 +
 drivers/hwmon/Makefile              |   1 +
 drivers/hwmon/tach-aspeed-ast2600.c | 692 ++++++++++++++++++++++++++++
 3 files changed, 702 insertions(+)
 create mode 100644 drivers/hwmon/tach-aspeed-ast2600.c

Comments

Guenter Roeck Oct. 31, 2022, 4:32 p.m. UTC | #1 
On Mon, Oct 31, 2022 at 06:38:08PM +0800, Billy Tsai wrote:
> This patch add the support of Tachometer which can use to monitor the
> frequency of the input. The tach supports up to 16 channels and it's part
> function of multi-function device "pwm-tach controller".
> 
> Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com>
> ---
>  drivers/hwmon/Kconfig               |   9 +
>  drivers/hwmon/Makefile              |   1 +
>  drivers/hwmon/tach-aspeed-ast2600.c | 692 ++++++++++++++++++++++++++++

Please also provide Documentation/hwmon/tach-aspeed-ast2600.rst.

[ ... ]

> +	hwmon = devm_hwmon_device_register_with_groups(dev, "aspeed_tach", priv,
> +						       priv->groups);

Please use the new hwmon api (devm_hwmon_device_register_with_info).

> +	ret = PTR_ERR_OR_ZERO(hwmon);
> +	if (ret) {
> +		dev_err_probe(dev, ret, "Failed to register hwmon device\n");
> +		goto err_assert_reset;
> +	}
> +	platform_set_drvdata(pdev, priv);
> +	return 0;
> +err_assert_reset:
> +	reset_control_assert(priv->reset);
> +err_disable_clk:
> +	clk_disable_unprepare(priv->clk);

You should be able to use devm_clk_get_enabled() to handle
the clock. If reset handling has to come first, you could use
devm_add_action_or_reset() for it. This way you would
not need the remove function, and error cleanup would
be much simplified.

Thanks,
Guenter

> +	return ret;
> +}
> +
> +static int aspeed_tach_remove(struct platform_device *pdev)
> +{
> +	struct aspeed_tach_data *priv = platform_get_drvdata(pdev);
> +
> +	reset_control_assert(priv->reset);
> +	clk_disable_unprepare(priv->clk);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id of_stach_match_table[] = {
> +	{
> +		.compatible = "aspeed,ast2600-tach",
> +	},
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, of_stach_match_table);
> +
> +static struct platform_driver aspeed_tach_driver = {
> +	.probe		= aspeed_tach_probe,
> +	.remove		= aspeed_tach_remove,
> +	.driver		= {
> +		.name	= "aspeed_tach",
> +		.of_match_table = of_stach_match_table,
> +	},
> +};
> +
> +module_platform_driver(aspeed_tach_driver);
> +
> +MODULE_AUTHOR("Billy Tsai <billy_tsai@aspeedtech.com>");
> +MODULE_DESCRIPTION("Aspeed ast2600 TACH device driver");
> +MODULE_LICENSE("GPL v2");
> +
> -- 
> 2.25.1
>
kernel test robot Nov. 2, 2022, 12:35 a.m. UTC | #2 
Hi Billy,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on groeck-staging/hwmon-next]
[also build test WARNING on thierry-reding-pwm/for-next lee-mfd/for-mfd-next robh/for-next linus/master v6.1-rc3 next-20221101]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Billy-Tsai/Support-pwm-tach-driver-for-aspeed-ast26xx/20221031-183813
base:   https://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging.git hwmon-next
patch link:    https://lore.kernel.org/r/20221031103809.20225-4-billy_tsai%40aspeedtech.com
patch subject: [PATCH 3/3] hwmon: Add Aspeed ast2600 TACH support
config: sparc-randconfig-s052-20221101
compiler: sparc64-linux-gcc (GCC) 12.1.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # apt-get install sparse
        # sparse version: v0.6.4-39-gce1a6720-dirty
        # https://github.com/intel-lab-lkp/linux/commit/34cbef9d62b8b6b352437c2ccaa6467de6524889
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Billy-Tsai/Support-pwm-tach-driver-for-aspeed-ast26xx/20221031-183813
        git checkout 34cbef9d62b8b6b352437c2ccaa6467de6524889
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=sparc SHELL=/bin/bash drivers/hwmon/ drivers/media/i2c/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

sparse warnings: (new ones prefixed by >>)
>> drivers/hwmon/tach-aspeed-ast2600.c:615:52: sparse: sparse: Using plain integer as NULL pointer

vim +615 drivers/hwmon/tach-aspeed-ast2600.c

   585	
   586	static int aspeed_tach_probe(struct platform_device *pdev)
   587	{
   588		struct device *dev = &pdev->dev;
   589		struct device_node *np, *child;
   590		struct aspeed_tach_data *priv;
   591		struct device *hwmon;
   592		struct platform_device *parent_dev;
   593		int ret;
   594	
   595		np = dev->parent->of_node;
   596		if (!of_device_is_compatible(np, "aspeed,ast2600-pwm-tach"))
   597			return dev_err_probe(dev, -ENODEV,
   598					     "Unsupported tach device binding\n");
   599	
   600		priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
   601		if (!priv)
   602			return -ENOMEM;
   603		priv->dev = &pdev->dev;
   604		priv->tach_channel =
   605			devm_kzalloc(dev,
   606				     TACH_ASPEED_NR_TACHS * sizeof(*priv->tach_channel),
   607				     GFP_KERNEL);
   608	
   609		priv->regmap = syscon_node_to_regmap(np);
   610		if (IS_ERR(priv->regmap)) {
   611			dev_err(priv->dev, "Couldn't get regmap\n");
   612			return -ENODEV;
   613		}
   614		parent_dev = of_find_device_by_node(np);
 > 615		priv->clk = devm_clk_get(&parent_dev->dev, 0);
   616		if (IS_ERR(priv->clk))
   617			return dev_err_probe(dev, PTR_ERR(priv->clk),
   618					     "Couldn't get clock\n");
   619	
   620		priv->reset = devm_reset_control_get_shared(&parent_dev->dev, NULL);
   621		if (IS_ERR(priv->reset))
   622			return dev_err_probe(dev, PTR_ERR(priv->reset),
   623					     "Couldn't get reset control\n");
   624	
   625		ret = clk_prepare_enable(priv->clk);
   626		if (ret)
   627			return dev_err_probe(dev, ret, "Couldn't enable clock\n");
   628	
   629		ret = reset_control_deassert(priv->reset);
   630		if (ret) {
   631			dev_err_probe(dev, ret, "Couldn't deassert reset control\n");
   632			goto err_disable_clk;
   633		}
   634		for_each_child_of_node(dev->of_node, child) {
   635			ret = aspeed_tach_create_fan(dev, child, priv);
   636			if (ret) {
   637				of_node_put(child);
   638				goto err_assert_reset;
   639			}
   640		}
   641	
   642		priv->groups[0] = &fan_dev_group;
   643		priv->groups[1] = NULL;
   644		hwmon = devm_hwmon_device_register_with_groups(dev, "aspeed_tach", priv,
   645							       priv->groups);
   646		ret = PTR_ERR_OR_ZERO(hwmon);
   647		if (ret) {
   648			dev_err_probe(dev, ret, "Failed to register hwmon device\n");
   649			goto err_assert_reset;
   650		}
   651		platform_set_drvdata(pdev, priv);
   652		return 0;
   653	err_assert_reset:
   654		reset_control_assert(priv->reset);
   655	err_disable_clk:
   656		clk_disable_unprepare(priv->clk);
   657		return ret;
   658	}
   659
diff mbox series

Patch

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index fa2356398744..a84c15b73aa6 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -397,6 +397,15 @@  config SENSORS_ASPEED
 	  This driver can also be built as a module. If so, the module
 	  will be called aspeed_pwm_tacho.
 
+config SENSORS_TACH_ASPEED_AST2600
+	tristate "ASPEED ast2600 Tachometer support"
+	select REGMAP
+	help
+	  This driver provides support for Aspeed ast2600 Tachometer.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called tach-aspeed-ast2600.
+
 config SENSORS_ATXP1
 	tristate "Attansic ATXP1 VID controller"
 	depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index d2497b2644e6..7e2d708e93b8 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -51,6 +51,7 @@  obj-$(CONFIG_SENSORS_ARM_SCMI)	+= scmi-hwmon.o
 obj-$(CONFIG_SENSORS_ARM_SCPI)	+= scpi-hwmon.o
 obj-$(CONFIG_SENSORS_AS370)	+= as370-hwmon.o
 obj-$(CONFIG_SENSORS_ASC7621)	+= asc7621.o
+obj-$(CONFIG_SENSORS_TACH_ASPEED_AST2600) += tach-aspeed-ast2600.o
 obj-$(CONFIG_SENSORS_ASPEED)	+= aspeed-pwm-tacho.o
 obj-$(CONFIG_SENSORS_ATXP1)	+= atxp1.o
 obj-$(CONFIG_SENSORS_AXI_FAN_CONTROL) += axi-fan-control.o
diff --git a/drivers/hwmon/tach-aspeed-ast2600.c b/drivers/hwmon/tach-aspeed-ast2600.c
new file mode 100644
index 000000000000..c5250ea8a16d
--- /dev/null
+++ b/drivers/hwmon/tach-aspeed-ast2600.c
@@ -0,0 +1,692 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) ASPEED Technology Inc.
+ */
+
+#include <linux/clk.h>
+#include <linux/errno.h>
+#include <linux/delay.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/syscon.h>
+#include <linux/sysfs.h>
+#include <linux/reset.h>
+#include <linux/regmap.h>
+#include <linux/bitfield.h>
+
+/* The channel number of Aspeed tach controller */
+#define TACH_ASPEED_NR_TACHS 16
+/* TACH Control Register */
+#define TACH_ASPEED_CTRL(ch) (((ch) * 0x10) + 0x08)
+#define TACH_ASPEED_IER BIT(31)
+#define TACH_ASPEED_INVERS_LIMIT BIT(30)
+#define TACH_ASPEED_LOOPBACK BIT(29)
+#define TACH_ASPEED_ENABLE BIT(28)
+#define TACH_ASPEED_DEBOUNCE_MASK GENMASK(27, 26)
+#define TACH_ASPEED_DEBOUNCE_BIT (26)
+#define TACH_ASPEED_IO_EDGE_MASK GENMASK(25, 24)
+#define TACH_ASPEED_IO_EDGE_BIT (24)
+#define TACH_ASPEED_CLK_DIV_T_MASK GENMASK(23, 20)
+#define TACH_ASPEED_CLK_DIV_BIT (20)
+#define TACH_ASPEED_THRESHOLD_MASK GENMASK(19, 0)
+/* [27:26] */
+#define DEBOUNCE_3_CLK 0x00
+#define DEBOUNCE_2_CLK 0x01
+#define DEBOUNCE_1_CLK 0x02
+#define DEBOUNCE_0_CLK 0x03
+/* [25:24] */
+#define F2F_EDGES 0x00
+#define R2R_EDGES 0x01
+#define BOTH_EDGES 0x02
+/* [23:20] */
+/* divisor = 4 to the nth power, n = register value */
+#define DEFAULT_TACH_DIV 1024
+#define DIV_TO_REG(divisor) (ilog2(divisor) >> 1)
+
+/* TACH Status Register */
+#define TACH_ASPEED_STS(ch) (((ch) * 0x10) + 0x0C)
+
+/*PWM_TACH_STS */
+#define TACH_ASPEED_ISR BIT(31)
+#define TACH_ASPEED_PWM_OUT BIT(25)
+#define TACH_ASPEED_PWM_OEN BIT(24)
+#define TACH_ASPEED_DEB_INPUT BIT(23)
+#define TACH_ASPEED_RAW_INPUT BIT(22)
+#define TACH_ASPEED_VALUE_UPDATE BIT(21)
+#define TACH_ASPEED_FULL_MEASUREMENT BIT(20)
+#define TACH_ASPEED_VALUE_MASK GENMASK(19, 0)
+/**********************************************************
+ * Software setting
+ *********************************************************/
+#define DEFAULT_FAN_MIN_RPM 1000
+#define DEFAULT_FAN_PULSE_PR 2
+/*
+ * Add this value to avoid CPU consuming a lot of resources in waiting rpm
+ * updating. Assume the max rpm of fan is 60000, the fastest period of updating
+ * tach value will be equal to (1000000 * 2 * 60) / (2 * max_rpm) = 1000us.
+ */
+#define DEFAULT_FAN_MAX_RPM 60000
+
+struct aspeed_tach_channel_params {
+	int limited_inverse;
+	u16 threshold;
+	u8 tach_edge;
+	u8 tach_debounce;
+	u8 pulse_pr;
+	u32 min_rpm;
+	u32 max_rpm;
+	u32 divisor;
+	u32 sample_period; /* unit is us */
+	u32 polling_period; /* unit is us */
+};
+
+struct aspeed_tach_data {
+	struct device *dev;
+	struct regmap *regmap;
+	struct clk *clk;
+	struct reset_control *reset;
+	bool tach_present[TACH_ASPEED_NR_TACHS];
+	struct aspeed_tach_channel_params *tach_channel;
+	/* for hwmon */
+	const struct attribute_group *groups[2];
+};
+
+static void aspeed_update_tach_sample_period(struct aspeed_tach_data *priv,
+					     u8 fan_tach_ch)
+{
+	u32 tach_period_us;
+	u8 pulse_pr = priv->tach_channel[fan_tach_ch].pulse_pr;
+	u32 min_rpm = priv->tach_channel[fan_tach_ch].min_rpm;
+
+	/*
+	 * min(Tach input clock) = (PulsePR * minRPM) / 60
+	 * max(Tach input period) = 60 / (PulsePR * minRPM)
+	 * Tach sample period > 2 * max(Tach input period) = (2*60) / (PulsePR * minRPM)
+	 */
+	tach_period_us = (USEC_PER_SEC * 2 * 60) / (pulse_pr * min_rpm);
+	/* Add the margin (about 1.5) of tach sample period to avoid sample miss */
+	tach_period_us = (tach_period_us * 1500) >> 10;
+	dev_dbg(priv->dev, "tach%d sample period = %dus", fan_tach_ch, tach_period_us);
+	priv->tach_channel[fan_tach_ch].sample_period = tach_period_us;
+}
+
+static void aspeed_update_tach_polling_period(struct aspeed_tach_data *priv,
+					     u8 fan_tach_ch)
+{
+	u32 tach_period_us;
+	u8 pulse_pr = priv->tach_channel[fan_tach_ch].pulse_pr;
+	u32 max_rpm = priv->tach_channel[fan_tach_ch].max_rpm;
+
+	tach_period_us = (USEC_PER_SEC * 2 * 60) / (pulse_pr * max_rpm);
+	dev_dbg(priv->dev, "tach%d polling period = %dus", fan_tach_ch, tach_period_us);
+	priv->tach_channel[fan_tach_ch].polling_period = tach_period_us;
+}
+
+static void aspeed_tach_ch_enable(struct aspeed_tach_data *priv, u8 tach_ch,
+				  bool enable)
+{
+	if (enable)
+		regmap_set_bits(priv->regmap, TACH_ASPEED_CTRL(tach_ch),
+				TACH_ASPEED_ENABLE);
+	else
+		regmap_clear_bits(priv->regmap, TACH_ASPEED_CTRL(tach_ch),
+				   TACH_ASPEED_ENABLE);
+}
+
+static int aspeed_get_fan_tach_ch_rpm(struct aspeed_tach_data *priv,
+				      u8 fan_tach_ch)
+{
+	u32 raw_data, tach_div, val;
+	unsigned long clk_source;
+	u64 rpm;
+	int ret;
+
+	/* Restart the Tach channel to guarantee the value is fresh */
+	aspeed_tach_ch_enable(priv, fan_tach_ch, false);
+	aspeed_tach_ch_enable(priv, fan_tach_ch, true);
+	ret = regmap_read_poll_timeout(
+		priv->regmap, TACH_ASPEED_STS(fan_tach_ch), val,
+		(val & TACH_ASPEED_FULL_MEASUREMENT) &&
+			(val & TACH_ASPEED_VALUE_UPDATE),
+		priv->tach_channel[fan_tach_ch].polling_period,
+		priv->tach_channel[fan_tach_ch].sample_period);
+
+	if (ret) {
+		/* return 0 if we didn't get an answer because of timeout*/
+		if (ret == -ETIMEDOUT)
+			return 0;
+		else
+			return ret;
+	}
+
+	raw_data = val & TACH_ASPEED_VALUE_MASK;
+	/*
+	 * We need the mode to determine if the raw_data is double (from
+	 * counting both edges).
+	 */
+	if (priv->tach_channel[fan_tach_ch].tach_edge == BOTH_EDGES)
+		raw_data <<= 1;
+
+	tach_div = raw_data * (priv->tach_channel[fan_tach_ch].divisor) *
+		   (priv->tach_channel[fan_tach_ch].pulse_pr);
+
+	clk_source = clk_get_rate(priv->clk);
+	dev_dbg(priv->dev, "clk %ld, raw_data %d , tach_div %d\n", clk_source,
+		raw_data, tach_div);
+
+	if (tach_div == 0)
+		return -EDOM;
+
+	rpm = (u64)clk_source * 60;
+	do_div(rpm, tach_div);
+
+	return rpm;
+}
+
+static ssize_t fan_show(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int index = sensor_attr->index;
+	int rpm;
+	struct aspeed_tach_data *priv = dev_get_drvdata(dev);
+
+	rpm = aspeed_get_fan_tach_ch_rpm(priv, index);
+	if (rpm < 0)
+		return rpm;
+
+	return sprintf(buf, "%d\n", rpm);
+}
+
+static umode_t fan_dev_is_visible(struct kobject *kobj, struct attribute *a,
+				  int index)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct aspeed_tach_data *priv = dev_get_drvdata(dev);
+
+	if (!priv->tach_present[index % TACH_ASPEED_NR_TACHS])
+		return 0;
+	return a->mode;
+}
+
+static SENSOR_DEVICE_ATTR_RO(fan1_input, fan, 0);
+static SENSOR_DEVICE_ATTR_RO(fan2_input, fan, 1);
+static SENSOR_DEVICE_ATTR_RO(fan3_input, fan, 2);
+static SENSOR_DEVICE_ATTR_RO(fan4_input, fan, 3);
+static SENSOR_DEVICE_ATTR_RO(fan5_input, fan, 4);
+static SENSOR_DEVICE_ATTR_RO(fan6_input, fan, 5);
+static SENSOR_DEVICE_ATTR_RO(fan7_input, fan, 6);
+static SENSOR_DEVICE_ATTR_RO(fan8_input, fan, 7);
+static SENSOR_DEVICE_ATTR_RO(fan9_input, fan, 8);
+static SENSOR_DEVICE_ATTR_RO(fan10_input, fan, 9);
+static SENSOR_DEVICE_ATTR_RO(fan11_input, fan, 10);
+static SENSOR_DEVICE_ATTR_RO(fan12_input, fan, 11);
+static SENSOR_DEVICE_ATTR_RO(fan13_input, fan, 12);
+static SENSOR_DEVICE_ATTR_RO(fan14_input, fan, 13);
+static SENSOR_DEVICE_ATTR_RO(fan15_input, fan, 14);
+static SENSOR_DEVICE_ATTR_RO(fan16_input, fan, 15);
+
+static ssize_t fan_max_show(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int index = sensor_attr->index;
+	struct aspeed_tach_data *priv = dev_get_drvdata(dev);
+	u32 max_rpm = priv->tach_channel[index].max_rpm;
+
+	return sprintf(buf, "%d\n", max_rpm);
+}
+
+static ssize_t fan_max_store(struct device *dev, struct device_attribute *attr,
+			     const char *buf, size_t count)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int index = sensor_attr->index;
+	struct aspeed_tach_data *priv = dev_get_drvdata(dev);
+	long max_rpm;
+	int ret;
+
+	ret = kstrtoul(buf, 10, &max_rpm);
+	if (ret < 0)
+		return ret;
+
+	priv->tach_channel[index].max_rpm = max_rpm;
+	aspeed_update_tach_polling_period(priv, index);
+	return count;
+}
+
+static SENSOR_DEVICE_ATTR_RW(fan1_max, fan_max, 0);
+static SENSOR_DEVICE_ATTR_RW(fan2_max, fan_max, 1);
+static SENSOR_DEVICE_ATTR_RW(fan3_max, fan_max, 2);
+static SENSOR_DEVICE_ATTR_RW(fan4_max, fan_max, 3);
+static SENSOR_DEVICE_ATTR_RW(fan5_max, fan_max, 4);
+static SENSOR_DEVICE_ATTR_RW(fan6_max, fan_max, 5);
+static SENSOR_DEVICE_ATTR_RW(fan7_max, fan_max, 6);
+static SENSOR_DEVICE_ATTR_RW(fan8_max, fan_max, 7);
+static SENSOR_DEVICE_ATTR_RW(fan9_max, fan_max, 8);
+static SENSOR_DEVICE_ATTR_RW(fan10_max, fan_max, 9);
+static SENSOR_DEVICE_ATTR_RW(fan11_max, fan_max, 10);
+static SENSOR_DEVICE_ATTR_RW(fan12_max, fan_max, 11);
+static SENSOR_DEVICE_ATTR_RW(fan13_max, fan_max, 12);
+static SENSOR_DEVICE_ATTR_RW(fan14_max, fan_max, 13);
+static SENSOR_DEVICE_ATTR_RW(fan15_max, fan_max, 14);
+static SENSOR_DEVICE_ATTR_RW(fan16_max, fan_max, 15);
+
+static ssize_t fan_min_show(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int index = sensor_attr->index;
+	struct aspeed_tach_data *priv = dev_get_drvdata(dev);
+	u32 min_rpm = priv->tach_channel[index].min_rpm;
+
+	return sprintf(buf, "%d\n", min_rpm);
+}
+
+static ssize_t fan_min_store(struct device *dev, struct device_attribute *attr,
+			     const char *buf, size_t count)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int index = sensor_attr->index;
+	struct aspeed_tach_data *priv = dev_get_drvdata(dev);
+	long min_rpm;
+	int ret;
+
+	ret = kstrtoul(buf, 10, &min_rpm);
+	if (ret < 0)
+		return ret;
+
+	priv->tach_channel[index].min_rpm = min_rpm;
+	aspeed_update_tach_sample_period(priv, index);
+	return count;
+}
+
+static SENSOR_DEVICE_ATTR_RW(fan1_min, fan_min, 0);
+static SENSOR_DEVICE_ATTR_RW(fan2_min, fan_min, 1);
+static SENSOR_DEVICE_ATTR_RW(fan3_min, fan_min, 2);
+static SENSOR_DEVICE_ATTR_RW(fan4_min, fan_min, 3);
+static SENSOR_DEVICE_ATTR_RW(fan5_min, fan_min, 4);
+static SENSOR_DEVICE_ATTR_RW(fan6_min, fan_min, 5);
+static SENSOR_DEVICE_ATTR_RW(fan7_min, fan_min, 6);
+static SENSOR_DEVICE_ATTR_RW(fan8_min, fan_min, 7);
+static SENSOR_DEVICE_ATTR_RW(fan9_min, fan_min, 8);
+static SENSOR_DEVICE_ATTR_RW(fan10_min, fan_min, 9);
+static SENSOR_DEVICE_ATTR_RW(fan11_min, fan_min, 10);
+static SENSOR_DEVICE_ATTR_RW(fan12_min, fan_min, 11);
+static SENSOR_DEVICE_ATTR_RW(fan13_min, fan_min, 12);
+static SENSOR_DEVICE_ATTR_RW(fan14_min, fan_min, 13);
+static SENSOR_DEVICE_ATTR_RW(fan15_min, fan_min, 14);
+static SENSOR_DEVICE_ATTR_RW(fan16_min, fan_min, 15);
+
+static ssize_t fan_pulse_show(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int index = sensor_attr->index;
+	struct aspeed_tach_data *priv = dev_get_drvdata(dev);
+	u32 pulse_pr = priv->tach_channel[index].pulse_pr;
+
+	return sprintf(buf, "%d\n", pulse_pr);
+}
+
+static ssize_t fan_pulse_store(struct device *dev, struct device_attribute *attr,
+			     const char *buf, size_t count)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int index = sensor_attr->index;
+	struct aspeed_tach_data *priv = dev_get_drvdata(dev);
+	long pulse_pr;
+	int ret;
+
+	ret = kstrtoul(buf, 10, &pulse_pr);
+	if (ret < 0)
+		return ret;
+
+	priv->tach_channel[index].pulse_pr = pulse_pr;
+	aspeed_update_tach_sample_period(priv, index);
+	return count;
+}
+
+static SENSOR_DEVICE_ATTR_RW(fan1_pulse, fan_pulse, 0);
+static SENSOR_DEVICE_ATTR_RW(fan2_pulse, fan_pulse, 1);
+static SENSOR_DEVICE_ATTR_RW(fan3_pulse, fan_pulse, 2);
+static SENSOR_DEVICE_ATTR_RW(fan4_pulse, fan_pulse, 3);
+static SENSOR_DEVICE_ATTR_RW(fan5_pulse, fan_pulse, 4);
+static SENSOR_DEVICE_ATTR_RW(fan6_pulse, fan_pulse, 5);
+static SENSOR_DEVICE_ATTR_RW(fan7_pulse, fan_pulse, 6);
+static SENSOR_DEVICE_ATTR_RW(fan8_pulse, fan_pulse, 7);
+static SENSOR_DEVICE_ATTR_RW(fan9_pulse, fan_pulse, 8);
+static SENSOR_DEVICE_ATTR_RW(fan10_pulse, fan_pulse, 9);
+static SENSOR_DEVICE_ATTR_RW(fan11_pulse, fan_pulse, 10);
+static SENSOR_DEVICE_ATTR_RW(fan12_pulse, fan_pulse, 11);
+static SENSOR_DEVICE_ATTR_RW(fan13_pulse, fan_pulse, 12);
+static SENSOR_DEVICE_ATTR_RW(fan14_pulse, fan_pulse, 13);
+static SENSOR_DEVICE_ATTR_RW(fan15_pulse, fan_pulse, 14);
+static SENSOR_DEVICE_ATTR_RW(fan16_pulse, fan_pulse, 15);
+
+static ssize_t fan_div_show(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int index = sensor_attr->index;
+	struct aspeed_tach_data *priv = dev_get_drvdata(dev);
+	u32 divisor, val = priv->tach_channel[index].divisor;
+
+	regmap_read(priv->regmap, TACH_ASPEED_CTRL(index), &val);
+	divisor = FIELD_GET(TACH_ASPEED_CLK_DIV_T_MASK, val);
+	divisor = 1 << (divisor << 1);
+
+	return sprintf(buf, "%d\n", divisor);
+}
+
+static ssize_t fan_div_store(struct device *dev, struct device_attribute *attr,
+			     const char *buf, size_t count)
+{
+	struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr);
+	int index = sensor_attr->index;
+	struct aspeed_tach_data *priv = dev_get_drvdata(dev);
+	long divisor;
+	int ret;
+
+	ret = kstrtoul(buf, 10, &divisor);
+	if (ret < 0)
+		return ret;
+
+	if ((is_power_of_2(divisor) && !(ilog2(divisor) % 2))) {
+		priv->tach_channel[index].divisor = divisor;
+		regmap_write_bits(priv->regmap, TACH_ASPEED_CTRL(index),
+				  TACH_ASPEED_CLK_DIV_T_MASK,
+				  DIV_TO_REG(priv->tach_channel[index].divisor)
+					  << TACH_ASPEED_CLK_DIV_BIT);
+	} else {
+		dev_err(dev,
+			"fan_div value %ld not supported. Only support power of 4\n",
+			divisor);
+		return -EINVAL;
+	}
+
+	return count;
+}
+
+static SENSOR_DEVICE_ATTR_RW(fan1_div, fan_div, 0);
+static SENSOR_DEVICE_ATTR_RW(fan2_div, fan_div, 1);
+static SENSOR_DEVICE_ATTR_RW(fan3_div, fan_div, 2);
+static SENSOR_DEVICE_ATTR_RW(fan4_div, fan_div, 3);
+static SENSOR_DEVICE_ATTR_RW(fan5_div, fan_div, 4);
+static SENSOR_DEVICE_ATTR_RW(fan6_div, fan_div, 5);
+static SENSOR_DEVICE_ATTR_RW(fan7_div, fan_div, 6);
+static SENSOR_DEVICE_ATTR_RW(fan8_div, fan_div, 7);
+static SENSOR_DEVICE_ATTR_RW(fan9_div, fan_div, 8);
+static SENSOR_DEVICE_ATTR_RW(fan10_div, fan_div, 9);
+static SENSOR_DEVICE_ATTR_RW(fan11_div, fan_div, 10);
+static SENSOR_DEVICE_ATTR_RW(fan12_div, fan_div, 11);
+static SENSOR_DEVICE_ATTR_RW(fan13_div, fan_div, 12);
+static SENSOR_DEVICE_ATTR_RW(fan14_div, fan_div, 13);
+static SENSOR_DEVICE_ATTR_RW(fan15_div, fan_div, 14);
+static SENSOR_DEVICE_ATTR_RW(fan16_div, fan_div, 15);
+
+static struct attribute *fan_dev_attrs[] = {
+	&sensor_dev_attr_fan1_input.dev_attr.attr,
+	&sensor_dev_attr_fan2_input.dev_attr.attr,
+	&sensor_dev_attr_fan3_input.dev_attr.attr,
+	&sensor_dev_attr_fan4_input.dev_attr.attr,
+	&sensor_dev_attr_fan5_input.dev_attr.attr,
+	&sensor_dev_attr_fan6_input.dev_attr.attr,
+	&sensor_dev_attr_fan7_input.dev_attr.attr,
+	&sensor_dev_attr_fan8_input.dev_attr.attr,
+	&sensor_dev_attr_fan9_input.dev_attr.attr,
+	&sensor_dev_attr_fan10_input.dev_attr.attr,
+	&sensor_dev_attr_fan11_input.dev_attr.attr,
+	&sensor_dev_attr_fan12_input.dev_attr.attr,
+	&sensor_dev_attr_fan13_input.dev_attr.attr,
+	&sensor_dev_attr_fan14_input.dev_attr.attr,
+	&sensor_dev_attr_fan15_input.dev_attr.attr,
+	&sensor_dev_attr_fan16_input.dev_attr.attr,
+
+	&sensor_dev_attr_fan1_max.dev_attr.attr,
+	&sensor_dev_attr_fan2_max.dev_attr.attr,
+	&sensor_dev_attr_fan3_max.dev_attr.attr,
+	&sensor_dev_attr_fan4_max.dev_attr.attr,
+	&sensor_dev_attr_fan5_max.dev_attr.attr,
+	&sensor_dev_attr_fan6_max.dev_attr.attr,
+	&sensor_dev_attr_fan7_max.dev_attr.attr,
+	&sensor_dev_attr_fan8_max.dev_attr.attr,
+	&sensor_dev_attr_fan9_max.dev_attr.attr,
+	&sensor_dev_attr_fan10_max.dev_attr.attr,
+	&sensor_dev_attr_fan11_max.dev_attr.attr,
+	&sensor_dev_attr_fan12_max.dev_attr.attr,
+	&sensor_dev_attr_fan13_max.dev_attr.attr,
+	&sensor_dev_attr_fan14_max.dev_attr.attr,
+	&sensor_dev_attr_fan15_max.dev_attr.attr,
+	&sensor_dev_attr_fan16_max.dev_attr.attr,
+
+	&sensor_dev_attr_fan1_min.dev_attr.attr,
+	&sensor_dev_attr_fan2_min.dev_attr.attr,
+	&sensor_dev_attr_fan3_min.dev_attr.attr,
+	&sensor_dev_attr_fan4_min.dev_attr.attr,
+	&sensor_dev_attr_fan5_min.dev_attr.attr,
+	&sensor_dev_attr_fan6_min.dev_attr.attr,
+	&sensor_dev_attr_fan7_min.dev_attr.attr,
+	&sensor_dev_attr_fan8_min.dev_attr.attr,
+	&sensor_dev_attr_fan9_min.dev_attr.attr,
+	&sensor_dev_attr_fan10_min.dev_attr.attr,
+	&sensor_dev_attr_fan11_min.dev_attr.attr,
+	&sensor_dev_attr_fan12_min.dev_attr.attr,
+	&sensor_dev_attr_fan13_min.dev_attr.attr,
+	&sensor_dev_attr_fan14_min.dev_attr.attr,
+	&sensor_dev_attr_fan15_min.dev_attr.attr,
+	&sensor_dev_attr_fan16_min.dev_attr.attr,
+
+	&sensor_dev_attr_fan1_div.dev_attr.attr,
+	&sensor_dev_attr_fan2_div.dev_attr.attr,
+	&sensor_dev_attr_fan3_div.dev_attr.attr,
+	&sensor_dev_attr_fan4_div.dev_attr.attr,
+	&sensor_dev_attr_fan5_div.dev_attr.attr,
+	&sensor_dev_attr_fan6_div.dev_attr.attr,
+	&sensor_dev_attr_fan7_div.dev_attr.attr,
+	&sensor_dev_attr_fan8_div.dev_attr.attr,
+	&sensor_dev_attr_fan9_div.dev_attr.attr,
+	&sensor_dev_attr_fan10_div.dev_attr.attr,
+	&sensor_dev_attr_fan11_div.dev_attr.attr,
+	&sensor_dev_attr_fan12_div.dev_attr.attr,
+	&sensor_dev_attr_fan13_div.dev_attr.attr,
+	&sensor_dev_attr_fan14_div.dev_attr.attr,
+	&sensor_dev_attr_fan15_div.dev_attr.attr,
+	&sensor_dev_attr_fan16_div.dev_attr.attr,
+
+	&sensor_dev_attr_fan1_pulse.dev_attr.attr,
+	&sensor_dev_attr_fan2_pulse.dev_attr.attr,
+	&sensor_dev_attr_fan3_pulse.dev_attr.attr,
+	&sensor_dev_attr_fan4_pulse.dev_attr.attr,
+	&sensor_dev_attr_fan5_pulse.dev_attr.attr,
+	&sensor_dev_attr_fan6_pulse.dev_attr.attr,
+	&sensor_dev_attr_fan7_pulse.dev_attr.attr,
+	&sensor_dev_attr_fan8_pulse.dev_attr.attr,
+	&sensor_dev_attr_fan9_pulse.dev_attr.attr,
+	&sensor_dev_attr_fan10_pulse.dev_attr.attr,
+	&sensor_dev_attr_fan11_pulse.dev_attr.attr,
+	&sensor_dev_attr_fan12_pulse.dev_attr.attr,
+	&sensor_dev_attr_fan13_pulse.dev_attr.attr,
+	&sensor_dev_attr_fan14_pulse.dev_attr.attr,
+	&sensor_dev_attr_fan15_pulse.dev_attr.attr,
+	&sensor_dev_attr_fan16_pulse.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group fan_dev_group = {
+	.attrs = fan_dev_attrs,
+	.is_visible = fan_dev_is_visible,
+};
+
+static void aspeed_create_fan_tach_channel(struct aspeed_tach_data *priv,
+					   u32 tach_ch)
+{
+	priv->tach_present[tach_ch] = true;
+	priv->tach_channel[tach_ch].limited_inverse = 0;
+	regmap_write_bits(priv->regmap, TACH_ASPEED_CTRL(tach_ch),
+			  TACH_ASPEED_INVERS_LIMIT,
+			  priv->tach_channel[tach_ch].limited_inverse ?
+				  TACH_ASPEED_INVERS_LIMIT :
+				  0);
+
+	priv->tach_channel[tach_ch].tach_debounce = DEBOUNCE_3_CLK;
+	regmap_write_bits(priv->regmap, TACH_ASPEED_CTRL(tach_ch),
+			  TACH_ASPEED_DEBOUNCE_MASK,
+			  priv->tach_channel[tach_ch].tach_debounce
+				  << TACH_ASPEED_DEBOUNCE_BIT);
+
+	priv->tach_channel[tach_ch].tach_edge = F2F_EDGES;
+	regmap_write_bits(priv->regmap, TACH_ASPEED_CTRL(tach_ch),
+			  TACH_ASPEED_IO_EDGE_MASK,
+			  priv->tach_channel[tach_ch].tach_edge
+				  << TACH_ASPEED_IO_EDGE_BIT);
+
+	priv->tach_channel[tach_ch].divisor = DEFAULT_TACH_DIV;
+	regmap_write_bits(priv->regmap, TACH_ASPEED_CTRL(tach_ch),
+			  TACH_ASPEED_CLK_DIV_T_MASK,
+			  DIV_TO_REG(priv->tach_channel[tach_ch].divisor)
+				  << TACH_ASPEED_CLK_DIV_BIT);
+
+	priv->tach_channel[tach_ch].threshold = 0;
+	regmap_write_bits(priv->regmap, TACH_ASPEED_CTRL(tach_ch),
+			  TACH_ASPEED_THRESHOLD_MASK,
+			  priv->tach_channel[tach_ch].threshold);
+
+	priv->tach_channel[tach_ch].pulse_pr = DEFAULT_FAN_PULSE_PR;
+	priv->tach_channel[tach_ch].min_rpm = DEFAULT_FAN_MIN_RPM;
+	aspeed_update_tach_sample_period(priv, tach_ch);
+
+	priv->tach_channel[tach_ch].max_rpm = DEFAULT_FAN_MAX_RPM;
+	aspeed_update_tach_polling_period(priv, tach_ch);
+
+	aspeed_tach_ch_enable(priv, tach_ch, true);
+}
+
+static int aspeed_tach_create_fan(struct device *dev, struct device_node *child,
+				  struct aspeed_tach_data *priv)
+{
+	u32 tach_channel;
+	int ret;
+
+	ret = of_property_read_u32(child, "reg", &tach_channel);
+	if (ret)
+		return ret;
+
+	aspeed_create_fan_tach_channel(priv, tach_channel);
+
+	return 0;
+}
+
+static int aspeed_tach_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np, *child;
+	struct aspeed_tach_data *priv;
+	struct device *hwmon;
+	struct platform_device *parent_dev;
+	int ret;
+
+	np = dev->parent->of_node;
+	if (!of_device_is_compatible(np, "aspeed,ast2600-pwm-tach"))
+		return dev_err_probe(dev, -ENODEV,
+				     "Unsupported tach device binding\n");
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+	priv->dev = &pdev->dev;
+	priv->tach_channel =
+		devm_kzalloc(dev,
+			     TACH_ASPEED_NR_TACHS * sizeof(*priv->tach_channel),
+			     GFP_KERNEL);
+
+	priv->regmap = syscon_node_to_regmap(np);
+	if (IS_ERR(priv->regmap)) {
+		dev_err(priv->dev, "Couldn't get regmap\n");
+		return -ENODEV;
+	}
+	parent_dev = of_find_device_by_node(np);
+	priv->clk = devm_clk_get(&parent_dev->dev, 0);
+	if (IS_ERR(priv->clk))
+		return dev_err_probe(dev, PTR_ERR(priv->clk),
+				     "Couldn't get clock\n");
+
+	priv->reset = devm_reset_control_get_shared(&parent_dev->dev, NULL);
+	if (IS_ERR(priv->reset))
+		return dev_err_probe(dev, PTR_ERR(priv->reset),
+				     "Couldn't get reset control\n");
+
+	ret = clk_prepare_enable(priv->clk);
+	if (ret)
+		return dev_err_probe(dev, ret, "Couldn't enable clock\n");
+
+	ret = reset_control_deassert(priv->reset);
+	if (ret) {
+		dev_err_probe(dev, ret, "Couldn't deassert reset control\n");
+		goto err_disable_clk;
+	}
+	for_each_child_of_node(dev->of_node, child) {
+		ret = aspeed_tach_create_fan(dev, child, priv);
+		if (ret) {
+			of_node_put(child);
+			goto err_assert_reset;
+		}
+	}
+
+	priv->groups[0] = &fan_dev_group;
+	priv->groups[1] = NULL;
+	hwmon = devm_hwmon_device_register_with_groups(dev, "aspeed_tach", priv,
+						       priv->groups);
+	ret = PTR_ERR_OR_ZERO(hwmon);
+	if (ret) {
+		dev_err_probe(dev, ret, "Failed to register hwmon device\n");
+		goto err_assert_reset;
+	}
+	platform_set_drvdata(pdev, priv);
+	return 0;
+err_assert_reset:
+	reset_control_assert(priv->reset);
+err_disable_clk:
+	clk_disable_unprepare(priv->clk);
+	return ret;
+}
+
+static int aspeed_tach_remove(struct platform_device *pdev)
+{
+	struct aspeed_tach_data *priv = platform_get_drvdata(pdev);
+
+	reset_control_assert(priv->reset);
+	clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+
+static const struct of_device_id of_stach_match_table[] = {
+	{
+		.compatible = "aspeed,ast2600-tach",
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, of_stach_match_table);
+
+static struct platform_driver aspeed_tach_driver = {
+	.probe		= aspeed_tach_probe,
+	.remove		= aspeed_tach_remove,
+	.driver		= {
+		.name	= "aspeed_tach",
+		.of_match_table = of_stach_match_table,
+	},
+};
+
+module_platform_driver(aspeed_tach_driver);
+
+MODULE_AUTHOR("Billy Tsai <billy_tsai@aspeedtech.com>");
+MODULE_DESCRIPTION("Aspeed ast2600 TACH device driver");
+MODULE_LICENSE("GPL v2");
+