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From:   Billy Tsai <billy_tsai@aspeedtech.com>
To:     <jdelvare@suse.com>, <linux@roeck-us.net>, <robh+dt@kernel.org>,
        <joel@jms.id.au>, <andrew@aj.id.au>, <lee.jones@linaro.org>,
        <thierry.reding@gmail.com>, <u.kleine-koenig@pengutronix.de>,
        <p.zabel@pengutronix.de>, <billy_tsai@aspeedtech.com>,
        <linux-hwmon@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-aspeed@lists.ozlabs.org>, <linux-kernel@vger.kernel.org>,
        <linux-pwm@vger.kernel.org>, <BMC-SW@aspeedtech.com>,
        <garnermic@meta.com>
Subject: [PATCH 3/3] hwmon: Add Aspeed ast2600 TACH support
Date:   Mon, 31 Oct 2022 18:38:08 +0800
Message-ID: <20221031103809.20225-4-billy_tsai@aspeedtech.com>
In-Reply-To: <20221031103809.20225-1-billy_tsai@aspeedtech.com>
References: <20221031103809.20225-1-billy_tsai@aspeedtech.com>
MIME-Version: 1.0
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Precedence: bulk

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

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");
+
-- 
2.25.1