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Date: Wed, 23 Nov 2022 07:44:56 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Billy Tsai <billy_tsai@...eedtech.com>, jdelvare@...e.com,
robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
joel@....id.au, andrew@...id.au, lee@...nel.org,
thierry.reding@...il.com, u.kleine-koenig@...gutronix.de,
corbet@....net, p.zabel@...gutronix.de,
linux-hwmon@...r.kernel.org, devicetree@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
linux-pwm@...r.kernel.org, linux-doc@...r.kernel.org
Cc: kernel test robot <lkp@...el.com>
Subject: Re: [v4 5/5] hwmon: Add Aspeed ast2600 TACH support
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@...eedtech.com>
> Reported-by: kernel test robot <lkp@...el.com>
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@...eedtech.com>
> +
> +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@...eedtech.com>");
> +MODULE_DESCRIPTION("Aspeed ast2600 TACH device driver");
> +MODULE_LICENSE("GPL");
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