Re: [v4 5/5] hwmon: Add Aspeed ast2600 TACH support
From: Guenter Roeck
Date: Wed Nov 23 2022 - 10:45:13 EST
On 11/22/22 22:16, Billy Tsai wrote:
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@xxxxxxxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
The above Reported-by: tag does not make sense for new drivers. Please drop.
Also, PATCH in subject is missing.
---
Documentation/hwmon/index.rst | 1 +
Documentation/hwmon/tach-aspeed-ast2600.rst | 24 ++
drivers/hwmon/Kconfig | 9 +
drivers/hwmon/Makefile | 1 +
drivers/hwmon/tach-aspeed-ast2600.c | 399 ++++++++++++++++++++
5 files changed, 434 insertions(+)
create mode 100644 Documentation/hwmon/tach-aspeed-ast2600.rst
create mode 100644 drivers/hwmon/tach-aspeed-ast2600.c
diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index c1d11cf13eef..8aed4c42ca89 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -193,6 +193,7 @@ Hardware Monitoring Kernel Drivers
sparx5-temp
stpddc60
sy7636a-hwmon
+ tach-aspeed-ast2600
tc654
tc74
thmc50
diff --git a/Documentation/hwmon/tach-aspeed-ast2600.rst b/Documentation/hwmon/tach-aspeed-ast2600.rst
new file mode 100644
index 000000000000..4f9501b783a1
--- /dev/null
+++ b/Documentation/hwmon/tach-aspeed-ast2600.rst
@@ -0,0 +1,24 @@
+Kernel driver tach-aspeed-ast2600
+==============================
+
+Supported chips:
+ ASPEED AST2600
+
+Authors:
+ <billy_tsai@xxxxxxxxxxxxxx>
+
+Description:
+------------
+This driver implements support for ASPEED AST2600 Fan Tacho controller.
+The controller supports up to 16 tachometer inputs.
+
+The driver provides the following sensor accesses in sysfs:
+=============== ======= =====================================================
+fanX_input ro provide current fan rotation value in RPM as reported
+ by the fan to the device.
+fanX_div rw Fan divisor: Supported value are power of 4 (1, 4, 16
+ 64, ... 4194304)
The code doesn't support 1.
+ The larger divisor, the less rpm accuracy and the less
+ affected by fan signal glitch.
+fanX_pulses rw Fan pulses per resolution.
+=============== ======= ======================================================
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 7ac3daaf59ce..3196087a7b3e 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -403,6 +403,15 @@ 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 11d076cad8a2..50a139c7c4ca 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -53,6 +53,7 @@ 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..2b8dd5eeb6ec
--- /dev/null
+++ b/drivers/hwmon/tach-aspeed-ast2600.c
@@ -0,0 +1,399 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) ASPEED Technology Inc.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/hwmon.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/reset.h>
+#include <linux/sysfs.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_PULSE_PR 2
+struct aspeed_tach_channel_params {
+ int limited_inverse;
+ u16 threshold;
+ u8 tach_edge;
+ u8 tach_debounce;
+ u8 pulse_pr;
+ 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;
+};
+
+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 u64 aspeed_tach_val_to_rpm(struct aspeed_tach_data *priv, u8 fan_tach_ch,
+ u32 tach_val)
+{
+ unsigned long clk_source;
+ u64 rpm;
+ u32 tach_div;
+
+ /*
+ * We need the mode to determine if the tach_val is double (from
+ * counting both edges).
+ */
+ if (priv->tach_channel[fan_tach_ch].tach_edge == BOTH_EDGES)
+ tach_val <<= 1;
+
+ tach_div = tach_val * (priv->tach_channel[fan_tach_ch].divisor) *
+ (priv->tach_channel[fan_tach_ch].pulse_pr);
+
+ clk_source = clk_get_rate(priv->clk);
Unless the clock rate can change (which is unlikely, I would suggest
to read it once during probe and re-use the value instead of reading it
repeatedly.
+ dev_dbg(priv->dev, "clk %ld, tach_val %d , tach_div %d\n", clk_source,
+ tach_val, tach_div);
+
+ rpm = (u64)clk_source * 60;
+ do_div(rpm, tach_div);
+
+ return rpm;
+}
+
+static int aspeed_get_fan_tach_ch_rpm(struct aspeed_tach_data *priv,
+ u8 fan_tach_ch)
+{
+ u32 val;
+ u64 rpm;
+ int ret;
+
+ ret = regmap_read(priv->regmap, TACH_ASPEED_STS(fan_tach_ch), &val);
+
Please drop this empty line.
The existence of a status register makes me wonder what is in there.
Does the controller report any errors ? If so, it might be worthwile
adding attribute(s) for it.
+ if (ret)
+ return ret;
+
+ if (!(val & TACH_ASPEED_FULL_MEASUREMENT))
+ return 0;
+ rpm = aspeed_tach_val_to_rpm(priv, fan_tach_ch,
+ val & TACH_ASPEED_VALUE_MASK);
+
+ return rpm;
+}
+
+static int aspeed_tach_hwmon_read(struct device *dev,
+ enum hwmon_sensor_types type, u32 attr,
+ int channel, long *val)
+{
+ struct aspeed_tach_data *priv = dev_get_drvdata(dev);
+ u32 reg_val;
+ int ret;
+
+ switch (attr) {
+ case hwmon_fan_input:
+ ret = aspeed_get_fan_tach_ch_rpm(priv, channel);
+ if (ret < 0)
+ return ret;
+ *val = ret;
+ break;
+ case hwmon_fan_div:
+ regmap_read(priv->regmap, TACH_ASPEED_CTRL(channel), ®_val);
+ reg_val = FIELD_GET(TACH_ASPEED_CLK_DIV_T_MASK, reg_val);
+ *val = BIT(reg_val << 1);
+ break;
+ case hwmon_fan_pulses:
+ *val = priv->tach_channel[channel].pulse_pr;
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+ return 0;
+}
+
+static int aspeed_tach_hwmon_write(struct device *dev,
+ enum hwmon_sensor_types type, u32 attr,
+ int channel, long val)
+{
+ struct aspeed_tach_data *priv = dev_get_drvdata(dev);
+
+ switch (attr) {
+ case hwmon_fan_div:
+ if (!(is_power_of_2(val) && !(ilog2(val) % 2))) {
+ dev_err(dev,
+ "fan_div value %ld not supported. Only support power of 4\n",
+ val);
Please refrain from error messages here. This only clogs the log as
result of user input.
The arithmetic is confusing.
if (!is_power_of_2(val) || (ilog2(val) % 2)))
would be much less confusing and easier to understand.
+ return -EINVAL;
+ }
There should be a range check. The above accepts a divisor value larger than 1024.
+ priv->tach_channel[channel].divisor = val;
+ regmap_write_bits(priv->regmap, TACH_ASPEED_CTRL(channel),
+ TACH_ASPEED_CLK_DIV_T_MASK,
+ DIV_TO_REG(priv->tach_channel[channel].divisor)
+ << TACH_ASPEED_CLK_DIV_BIT);
+ break;
+ case hwmon_fan_pulses:
+ priv->tach_channel[channel].pulse_pr = val;
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+
+ return 0;
+}
+
+static umode_t aspeed_tach_dev_is_visible(const void *drvdata,
+ enum hwmon_sensor_types type,
+ u32 attr, int channel)
+{
+ const struct aspeed_tach_data *priv = drvdata;
+
+ if (!priv->tach_present[channel])
+ return 0;
+ switch (attr) {
+ case hwmon_fan_input:
+ return 0444;
+ case hwmon_fan_div:
+ case hwmon_fan_pulses:
+ return 0644;
+ }
+ return 0;
+}
+
+static const struct hwmon_ops aspeed_tach_ops = {
+ .is_visible = aspeed_tach_dev_is_visible,
+ .read = aspeed_tach_hwmon_read,
+ .write = aspeed_tach_hwmon_write,
+};
+
+static const struct hwmon_channel_info *aspeed_tach_info[] = {
+ HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_PULSES,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_PULSES,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_PULSES,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_PULSES,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_PULSES,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_PULSES,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_PULSES,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_PULSES,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_PULSES,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_PULSES,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_PULSES,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_PULSES,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_PULSES,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_PULSES,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_PULSES,
+ HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_PULSES),
+ NULL
+};
+
+static const struct hwmon_chip_info aspeed_tach_chip_info = {
+ .ops = &aspeed_tach_ops,
+ .info = aspeed_tach_info,
+};
+
+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);
+
What is the purpose of the above code ? limited_inverse is always 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);
+
limited_inverse, tach_debounce, and tach_edge are constants.
There is no need to keep constants as per-channel variables.
+ 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);
+
The above applies to threshold as well.
+ priv->tach_channel[tach_ch].pulse_pr = DEFAULT_FAN_PULSE_PR;
+
+ aspeed_tach_ch_enable(priv, tach_ch, true);
+}
+
I kind of can understand that there are no devicetree properties given the
discussion around it. It is still unfortunate since being involved in that
discussion might help ensure that a generic property such as fan divisor value
ends up being supported in the upcoming generic properties.
+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 void aspeed_tach_reset_assert(void *data)
+{
+ struct reset_control *rst = data;
+
+ reset_control_assert(rst);
+}
+
+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_kcalloc(dev, TACH_ASPEED_NR_TACHS,
+ sizeof(*priv->tach_channel), GFP_KERNEL);
+ if (!priv->tach_channel)
+ return -ENOMEM;
Why not allocate tach_channel as array within aspeed_tach_data ?
+
+ priv->regmap = syscon_node_to_regmap(np);
+ if (IS_ERR(priv->regmap))
+ return dev_err_probe(dev, PTR_ERR(priv->regmap),
+ "Couldn't get regmap\n");
+ parent_dev = of_find_device_by_node(np);
Isn't that the same as dev->parent ?
+ priv->clk = devm_clk_get_enabled(&parent_dev->dev, NULL);
+ 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 = reset_control_deassert(priv->reset);
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "Couldn't deassert reset control\n");
+
+ ret = devm_add_action_or_reset(dev, aspeed_tach_reset_assert,
+ priv->reset);
+ if (ret)
+ return ret;
+
+ for_each_child_of_node(dev->of_node, child) {
+ ret = aspeed_tach_create_fan(dev, child, priv);
+ if (ret) {
+ of_node_put(child);
+ return ret;
+ }
+ }
+
+ hwmon = devm_hwmon_device_register_with_info(dev, "aspeed_tach", priv,
+ &aspeed_tach_chip_info, NULL);
+ ret = PTR_ERR_OR_ZERO(hwmon);
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "Failed to register hwmon device\n");
+ return 0;
Why not return the error ? Either it is an error or it isn't. If it is
not an error, dev_err_probe() is not appropriate. If it is, the error
should be returned. Either case, if this is on purpose, it needs an
explanation.
+}
+
+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,
+ .driver = {
+ .name = "aspeed_tach",
+ .of_match_table = of_stach_match_table,
+ },
+};
+
+module_platform_driver(aspeed_tach_driver);
+
+MODULE_AUTHOR("Billy Tsai <billy_tsai@xxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Aspeed ast2600 TACH device driver");
+MODULE_LICENSE("GPL");