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Date: Thu, 18 Jun 2020 13:31:24 +0200
From: Lars Povlsen <lars.povlsen@...rochip.com>
To: Guenter Roeck <linux@...ck-us.net>
CC: Lars Povlsen <lars.povlsen@...rochip.com>,
Jean Delvare <jdelvare@...e.com>,
Microchip Linux Driver Support <UNGLinuxDriver@...rochip.com>,
<linux-hwmon@...r.kernel.org>, <devicetree@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>,
Alexandre Belloni <alexandre.belloni@...tlin.com>
Subject: Re: [PATCH v3 3/3] hwmon: sparx5: Add Sparx5 SoC temperature driver
Guenter Roeck writes:
> On 6/16/20 1:25 AM, Lars Povlsen wrote:
>> This patch adds a temperature sensor driver to the Sparx5 SoC.
>>
>> Signed-off-by: Lars Povlsen <lars.povlsen@...rochip.com>
>> ---
>> drivers/hwmon/Kconfig | 10 +++
>> drivers/hwmon/Makefile | 1 +
>> drivers/hwmon/sparx5-temp.c | 136 ++++++++++++++++++++++++++++++++++++
>
> This will also require documentation in
> Documentation/hwmon/sparx5-temp.rst
>
>> 3 files changed, 147 insertions(+)
>> create mode 100644 drivers/hwmon/sparx5-temp.c
>>
>> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
>> index 288ae9f63588c..7fb5e0c6c6306 100644
>> --- a/drivers/hwmon/Kconfig
>> +++ b/drivers/hwmon/Kconfig
>> @@ -515,6 +515,16 @@ config SENSORS_I5K_AMB
>> This driver can also be built as a module. If so, the module
>> will be called i5k_amb.
>>
>> +config SENSORS_SPARX5
>> + tristate "Sparx5 SoC temperature sensor"
>> + depends on ARCH_SPARX5 || COMPILE_TEST
>> + help
>> + If you say yes here you get support for temperature monitoring
>> + with the Microchip Sparx5 SoC.
>> +
>> + This driver can also be built as a module. If so, the module
>> + will be called sparx5-temp.
>> +
>> config SENSORS_F71805F
>> tristate "Fintek F71805F/FG, F71806F/FG and F71872F/FG"
>> depends on !PPC
>> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
>> index 3e32c21f5efe3..857293f650412 100644
>> --- a/drivers/hwmon/Makefile
>> +++ b/drivers/hwmon/Makefile
>> @@ -167,6 +167,7 @@ obj-$(CONFIG_SENSORS_SMM665) += smm665.o
>> obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o
>> obj-$(CONFIG_SENSORS_SMSC47M1) += smsc47m1.o
>> obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
>> +obj-$(CONFIG_SENSORS_SPARX5) += sparx5-temp.o
>> obj-$(CONFIG_SENSORS_STTS751) += stts751.o
>> obj-$(CONFIG_SENSORS_AMC6821) += amc6821.o
>> obj-$(CONFIG_SENSORS_TC74) += tc74.o
>> diff --git a/drivers/hwmon/sparx5-temp.c b/drivers/hwmon/sparx5-temp.c
>> new file mode 100644
>> index 0000000000000..4ed8a2aec3ae9
>> --- /dev/null
>> +++ b/drivers/hwmon/sparx5-temp.c
>> @@ -0,0 +1,136 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +/* Sparx5 SoC temperature sensor driver
>> + *
>> + * Copyright (C) 2020 Lars Povlsen <lars.povlsen@...rochip.com>
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/init.h>
>> +#include <linux/hwmon.h>
>> +#include <linux/io.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/mod_devicetable.h>
>> +#include <linux/bitfield.h>
>
> Alphabetic order, please.
Ack.
>
>> +
>> +#define TEMP_CTRL 0
>> +#define TEMP_CFG 4
>> +#define TEMP_CFG_CYCLES GENMASK(24, 15)
>> +#define TEMP_CFG_ENA BIT(0)
>> +#define TEMP_STAT 8
>> +#define TEMP_STAT_VALID BIT(12)
>> +#define TEMP_STAT_TEMP GENMASK(11, 0)
>> +
>> +struct s5_hwmon {
>> + void __iomem *base;
>> +};
>> +
>> +static void s5_temp_enable(struct s5_hwmon *hwmon)
>> +{
>> + u32 val = readl(hwmon->base + TEMP_CFG);
>> + u32 clk = 250;
>> +
>
> Unnecessary variable, and magic number. It would be better to use a define
> or at least explain what the number is for. Also, if this is associated with
> a system clock, would it make sense to use the clock subsystem API to get
> the rate ?
>
Yes, valid point. Changed to reference the system AHB clock, so DT and
bindings updated as well. (The magic number is clock ticks per 1us).
I am sending an update asap.
Thank you for your comments, they are highly appreciated!
Cheers,
---Lars
>> + val &= ~TEMP_CFG_CYCLES;
>> + val |= FIELD_PREP(TEMP_CFG_CYCLES, clk);
>> + val |= TEMP_CFG_ENA;
>> +
>> + writel(val, hwmon->base + TEMP_CFG);
>> +}
>> +
>> +static int s5_read(struct device *dev, enum hwmon_sensor_types type,
>> + u32 attr, int channel, long *temp)
>> +{
>> + struct s5_hwmon *hwmon = dev_get_drvdata(dev);
>> + int rc = 0, value;
>> + u32 stat;
>> +
>> + switch (attr) {
>> + case hwmon_temp_input:
>> + stat = readl_relaxed(hwmon->base + TEMP_STAT);
>> + if (!(stat & TEMP_STAT_VALID))
>> + return -EIO;
>> + value = stat & TEMP_STAT_TEMP;
>> + value = DIV_ROUND_CLOSEST(value * 3522, 4096) - 1094;
>
> A comment describing the calculation would be useful, not only to help
> the reader but also to help me verify if the calculation is correct
> (especially since datasheets don't seem to be public).
>
I have added the register docs and commented the calculations.
>> + value *= 100;
>> + *temp = value;
>> + break;
>> + default:
>> + rc = -EOPNOTSUPP;
>> + break;
>> + }
>> +
>> + return rc;
>> +}
>> +
>> +static umode_t s5_is_visible(const void *_data, enum hwmon_sensor_types type,
>> + u32 attr, int channel)
>> +{
>> + if (type != hwmon_temp)
>> + return 0;
>> +
>> + switch (attr) {
>> + case hwmon_temp_input:
>> + return 0444;
>> + default:
>> + return 0;
>> + }
>> +}
>> +
>> +static const struct hwmon_channel_info *s5_info[] = {
>> + HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
>> + HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
>> + NULL
>> +};
>> +
>> +static const struct hwmon_ops s5_hwmon_ops = {
>> + .is_visible = s5_is_visible,
>> + .read = s5_read,
>> +};
>> +
>> +static const struct hwmon_chip_info s5_chip_info = {
>> + .ops = &s5_hwmon_ops,
>> + .info = s5_info,
>> +};
>> +
>> +static int s5_temp_probe(struct platform_device *pdev)
>> +{
>> + struct device *hwmon_dev;
>> + struct s5_hwmon *hwmon;
>> +
>> + hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
>> + if (!hwmon)
>> + return -ENOMEM;
>> +
>> + hwmon->base = devm_platform_ioremap_resource(pdev, 0);
>> + if (IS_ERR(hwmon->base))
>> + return PTR_ERR(hwmon->base);
>> +
>> + s5_temp_enable(hwmon);
>> +
>> + hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
>> + "s5_temp",
>> + hwmon,
>> + &s5_chip_info,
>> + NULL);
>> +
>> + return PTR_ERR_OR_ZERO(hwmon_dev);
>> +}
>> +
>> +const struct of_device_id s5_temp_match[] = {
>> + { .compatible = "microchip,sparx5-temp" },
>> + {},
>> +};
>> +MODULE_DEVICE_TABLE(of, s5_temp_match);
>> +
>> +static struct platform_driver s5_temp_driver = {
>> + .probe = s5_temp_probe,
>> + .driver = {
>> + .name = "sparx5-temp",
>> + .of_match_table = s5_temp_match,
>> + },
>> +};
>> +
>> +module_platform_driver(s5_temp_driver);
>> +
>> +MODULE_AUTHOR("Lars Povlsen <lars.povlsen@...rochip.com>");
>> +MODULE_DESCRIPTION("Sparx5 SoC temperature sensor driver");
>> +MODULE_LICENSE("GPL");
>>
--
Lars Povlsen,
Microchip
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