Date:   Thu, 2 Feb 2023 22:12:47 +0100
From:   Armin Wolf <W_Armin@....de>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     hdegoede@...hat.com, markgross@...nel.org, jdelvare@...e.com,
        platform-driver-x86@...r.kernel.org, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/5] platform/x86: dell-ddv: Add hwmon support

Am 27.01.23 um 17:09 schrieb Armin Wolf:

> Am 27.01.23 um 14:08 schrieb Guenter Roeck:
>
>> On Thu, Jan 26, 2023 at 08:40:21PM +0100, Armin Wolf wrote:
>>> Thanks to bugreport 216655 on bugzilla triggered by the
>>> dell-smm-hwmon driver, the contents of the sensor buffers
>>> could be almost completely decoded.
>>> Add an hwmon interface for exposing the fan and thermal
>>> sensor values. The debugfs interface remains in place to
>>> aid in reverse-engineering of unknown sensor types
>>> and the thermal buffer.
>>>
>>> Tested-by: Antonín Skala <skala.antonin@...il.com>
>>> Tested-by: Gustavo Walbon <gustavowalbon@...il.com>
>>> Signed-off-by: Armin Wolf <W_Armin@....de>
>>> ---
>>>   drivers/platform/x86/dell/Kconfig        |   1 +
>>>   drivers/platform/x86/dell/dell-wmi-ddv.c | 435 
>>> ++++++++++++++++++++++-
>>>   2 files changed, 435 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/platform/x86/dell/Kconfig 
>>> b/drivers/platform/x86/dell/Kconfig
>>> index d319de8f2132..21a74b63d9b1 100644
>>> --- a/drivers/platform/x86/dell/Kconfig
>>> +++ b/drivers/platform/x86/dell/Kconfig
>>> @@ -194,6 +194,7 @@ config DELL_WMI_DDV
>>>       default m
>>>       depends on ACPI_BATTERY
>>>       depends on ACPI_WMI
>>> +    depends on HWMON
>> Not sure if adding such a dependency is a good idea.
>> Up to the maintainer to decide. Personally I would prefer
>> something like
>>     depends on HWMON || HWMON=n
>> and some conditionals in the code, as it is done with other drivers
>> outside the hwmon directory.
>>
> Good point, i will include this in the next patch revision.
>
>>>       help
>>>         This option adds support for WMI-based sensors like
>>>         battery temperature sensors found on some Dell notebooks.
>>> diff --git a/drivers/platform/x86/dell/dell-wmi-ddv.c 
>>> b/drivers/platform/x86/dell/dell-wmi-ddv.c
>>> index 9695bf493ea6..5b30bb85199e 100644
>>> --- a/drivers/platform/x86/dell/dell-wmi-ddv.c
>>> +++ b/drivers/platform/x86/dell/dell-wmi-ddv.c
>>> @@ -13,6 +13,7 @@
>>>   #include <linux/dev_printk.h>
>>>   #include <linux/errno.h>
>>>   #include <linux/kernel.h>
>>> +#include <linux/hwmon.h>
>>>   #include <linux/kstrtox.h>
>>>   #include <linux/math.h>
>>>   #include <linux/module.h>
>>> @@ -21,10 +22,13 @@
>>>   #include <linux/printk.h>
>>>   #include <linux/seq_file.h>
>>>   #include <linux/sysfs.h>
>>> +#include <linux/types.h>
>>>   #include <linux/wmi.h>
>>>
>>>   #include <acpi/battery.h>
>>>
>>> +#include <asm/unaligned.h>
>>> +
>>>   #define DRIVER_NAME    "dell-wmi-ddv"
>>>
>>>   #define DELL_DDV_SUPPORTED_VERSION_MIN    2
>>> @@ -63,6 +67,29 @@ enum dell_ddv_method {
>>>       DELL_DDV_THERMAL_SENSOR_INFORMATION    = 0x22,
>>>   };
>>>
>>> +struct fan_sensor_entry {
>>> +    u8 type;
>>> +    __le16 rpm;
>>> +} __packed;
>>> +
>>> +struct thermal_sensor_entry {
>>> +    u8 type;
>>> +    s8 now;
>>> +    s8 min;
>>> +    s8 max;
>>> +    u8 unknown;
>>> +} __packed;
>>> +
>>> +struct combined_channel_info {
>>> +    struct hwmon_channel_info info;
>>> +    u32 config[];
>>> +};
>>> +
>>> +struct combined_chip_info {
>>> +    struct hwmon_chip_info chip;
>>> +    const struct hwmon_channel_info *info[];
>>> +};
>>> +
>>>   struct dell_wmi_ddv_data {
>>>       struct acpi_battery_hook hook;
>>>       struct device_attribute temp_attr;
>>> @@ -70,6 +97,24 @@ struct dell_wmi_ddv_data {
>>>       struct wmi_device *wdev;
>>>   };
>>>
>>> +static const char * const fan_labels[] = {
>>> +    "CPU Fan",
>>> +    "Chassis Motherboard Fan",
>>> +    "Video Fan",
>>> +    "Power Supply Fan",
>>> +    "Chipset Fan",
>>> +    "Memory Fan",
>>> +    "PCI Fan",
>>> +    "HDD Fan",
>>> +};
>>> +
>>> +static const char * const fan_dock_labels[] = {
>>> +    "Docking Chassis/Motherboard Fan",
>>> +    "Docking Video Fan",
>>> +    "Docking Power Supply Fan",
>>> +    "Docking Chipset Fan",
>>> +};
>>> +
>>>   static int dell_wmi_ddv_query_type(struct wmi_device *wdev, enum 
>>> dell_ddv_method method, u32 arg,
>>>                      union acpi_object **result, acpi_object_type type)
>>>   {
>>> @@ -171,6 +216,386 @@ static int dell_wmi_ddv_query_string(struct 
>>> wmi_device *wdev, enum dell_ddv_meth
>>>       return dell_wmi_ddv_query_type(wdev, method, arg, result, 
>>> ACPI_TYPE_STRING);
>>>   }
>>>
>>> +static int dell_wmi_ddv_query_sensors(struct wmi_device *wdev, enum 
>>> dell_ddv_method method,
>>> +                      size_t entry_size, union acpi_object 
>>> **result, u64 *count)
>>> +{
>>> +    union acpi_object *obj;
>>> +    u64 buffer_size;
>>> +    u8 *buffer;
>>> +    int ret;
>>> +
>>> +    ret = dell_wmi_ddv_query_buffer(wdev, method, 0, &obj);
>>> +    if (ret < 0)
>>> +        return ret;
>>> +
>>> +    buffer_size = obj->package.elements[0].integer.value;
>>> +    buffer = obj->package.elements[1].buffer.pointer;
>>> +    if (buffer_size % entry_size != 1 || buffer[buffer_size - 1] != 
>>> 0xff) {
>>> +        kfree(obj);
>>> +
>> Stray empty line
>>
>>> +        return -ENOMSG;
>>> +    }
>>> +
>>> +    *count = (buffer_size - 1) / entry_size;
>>> +    *result = obj;
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +static umode_t dell_wmi_ddv_is_visible(const void *drvdata, enum 
>>> hwmon_sensor_types type, u32 attr,
>>> +                       int channel)
>>> +{
>>> +    return 0444;
>>> +}
>>> +
>>> +static int dell_wmi_ddv_fan_read_channel(struct dell_wmi_ddv_data 
>>> *data, u32 attr, int channel,
>>> +                     long *val)
>>> +{
>>> +    struct fan_sensor_entry *entry;
>>> +    union acpi_object *obj;
>>> +    u64 count;
>>> +    int ret;
>>> +
>>> +    ret = dell_wmi_ddv_query_sensors(data->wdev, 
>>> DELL_DDV_FAN_SENSOR_INFORMATION,
>>> +                     sizeof(*entry), &obj, &count);
>>> +    if (ret < 0)
>>> +        return ret;
>>> +
>>> +    entry = (struct fan_sensor_entry 
>>> *)obj->package.elements[1].buffer.pointer;
>>> +    if (count > channel) {
>>> +        switch (attr) {
>>> +        case hwmon_fan_input:
>>> +            *val = get_unaligned_le16(&entry[channel].rpm);
>>> +
>> Another stray empty line. I see that "empty line before return or break"
>> is common. Looks odd to me, and I don't see the point (it confuses
>> the code flow for me and lets my brain focus on the empty line instead
>> of the code in question), but I guess that is PoV. I won't comment on
>> it further and let the maintainer decide.
>>
>>> +            break;
>>> +        default:
>>> +            ret = -EOPNOTSUPP;
>>> +        }
>>> +    } else {
>>> +        ret = -ENXIO;
>>> +    }
>> Error handling should come first.
>>> +
>>> +    kfree(obj);
>>> +
>>> +    return ret;
>>> +}
>>> +
>>> +static int dell_wmi_ddv_temp_read_channel(struct dell_wmi_ddv_data 
>>> *data, u32 attr, int channel,
>>> +                      long *val)
>>> +{
>>> +    struct thermal_sensor_entry *entry;
>>> +    union acpi_object *obj;
>>> +    u64 count;
>>> +    int ret;
>>> +
>>> +    ret = dell_wmi_ddv_query_sensors(data->wdev, 
>>> DELL_DDV_THERMAL_SENSOR_INFORMATION,
>>> +                     sizeof(*entry), &obj, &count);
>>> +    if (ret < 0)
>>> +        return ret;
>>> +
>>> +    entry = (struct thermal_sensor_entry 
>>> *)obj->package.elements[1].buffer.pointer;
>>> +    if (count > channel) {
>> This is a bit of Joda programming. It is really "channel < count",
>> ie the requested channel number is in the range of channels reported
>> by the WMI code. PoV, of course, but I find that the above makes the
>> code more difficult to read.
>>> +        switch (attr) {
>>> +        case hwmon_temp_input:
>>> +            *val = entry[channel].now * 1000;
>>> +
>>> +            break;
>>> +        case hwmon_temp_min:
>>> +            *val = entry[channel].min * 1000;
>>> +
>>> +            break;
>>> +        case hwmon_temp_max:
>>> +            *val = entry[channel].max * 1000;
>>> +
>>> +            break;
>>> +        default:
>>> +            ret = -EOPNOTSUPP;
>> break; missing
>>
>>> +        }
>>> +    } else {
>>> +        ret = -ENXIO;
>>> +    }
>> Same as above - error handling should come first.
>>
>>> +
>>> +    kfree(obj);
>>> +
>>> +    return ret;
>>> +}
>>> +
>>> +static int dell_wmi_ddv_read(struct device *dev, enum 
>>> hwmon_sensor_types type, u32 attr,
>>> +                 int channel, long *val)
>>> +{
>>> +    struct dell_wmi_ddv_data *data = dev_get_drvdata(dev);
>>> +
>>> +    switch (type) {
>>> +    case hwmon_fan:
>>> +        return dell_wmi_ddv_fan_read_channel(data, attr, channel, 
>>> val);
>>> +    case hwmon_temp:
>>> +        return dell_wmi_ddv_temp_read_channel(data, attr, channel, 
>>> val);
>>> +    default:
>>> +        break;
>>> +    }
>>> +
>>> +    return -EOPNOTSUPP;
>>> +}
>>> +
>>> +static int dell_wmi_ddv_fan_read_string(struct dell_wmi_ddv_data 
>>> *data, int channel,
>>> +                    const char **str)
>>> +{
>>> +    struct fan_sensor_entry *entry;
>>> +    union acpi_object *obj;
>>> +    u64 count;
>>> +    u8 type;
>>> +    int ret;
>>> +
>>> +    ret = dell_wmi_ddv_query_sensors(data->wdev, 
>>> DELL_DDV_FAN_SENSOR_INFORMATION,
>>> +                     sizeof(*entry), &obj, &count);
>>> +    if (ret < 0)
>>> +        return ret;
>>> +
>>> +    entry = (struct fan_sensor_entry 
>>> *)obj->package.elements[1].buffer.pointer;
>>> +    if (count > channel) {
>>> +        type = entry[channel].type;
>>> +
>>> +        switch (type) {
>>> +        case 0x00 ... 0x07:
>>> +            *str = fan_labels[type];
>>> +
>>> +            break;
>>> +        case 0x11 ... 0x14:
>>> +            *str = fan_dock_labels[type - 0x11];
>>> +
>>> +            break;
>>> +        default:
>>> +            *str = "Unknown Fan";
>> break; missing.
>>
>>> +        }
>>> +    } else {
>>> +        ret = -ENXIO;
>>> +    }
>> And again.
>>
>>> +
>>> +    kfree(obj);
>>> +
>>> +    return ret;
>>> +}
>>> +
>>> +static int dell_wmi_ddv_temp_read_string(struct dell_wmi_ddv_data 
>>> *data, int channel,
>>> +                     const char **str)
>>> +{
>>> +    struct thermal_sensor_entry *entry;
>>> +    union acpi_object *obj;
>>> +    u64 count;
>>> +    int ret;
>>> +
>>> +    ret = dell_wmi_ddv_query_sensors(data->wdev, 
>>> DELL_DDV_THERMAL_SENSOR_INFORMATION,
>>> +                     sizeof(*entry), &obj, &count);
>>> +    if (ret < 0)
>>> +        return ret;
>>> +
>>> +    entry = (struct thermal_sensor_entry 
>>> *)obj->package.elements[1].buffer.pointer;
>>> +    if (count > channel) {
>>> +        switch (entry[channel].type) {
>>> +        case 0x00:
>>> +            *str = "CPU";
>>> +
>>> +            break;
>>> +        case 0x11:
>>> +            *str = "Video";
>>> +
>>> +            break;
>>> +        case 0x22:
>>> +            *str = "Memory"; // sometimes called DIMM
>> Personally I don't permit C++ style comments in a hwmon driver
>> unless _all_ comments are C++ style. Just a remark here.
>>
>>> +
>>> +            break;
>>> +        case 0x33:
>>> +            *str = "Other";
>>> +
>>> +            break;
>>> +        case 0x44:
>>> +            *str = "Ambient"; // sometimes called SKIN
>>> +
>>> +            break;
>>> +        case 0x52:
>>> +            *str = "SODIMM";
>>> +
>>> +            break;
>>> +        case 0x55:
>>> +            *str = "HDD";
>>> +
>>> +            break;
>>> +        case 0x62:
>>> +            *str = "SODIMM 2";
>>> +
>>> +            break;
>>> +        case 0x73:
>>> +            *str = "NB";
>>> +
>>> +            break;
>>> +        case 0x83:
>>> +            *str = "Charger";
>>> +
>>> +            break;
>>> +        case 0xbb:
>>> +            *str = "Memory 3";
>>> +
>>> +            break;
>>> +        default:
>>> +            *str = "Unknown";
>> break; missing
>> Ok, I guess this is on purpose. I personally don't permit
>> that since it always leaves the question if it was on purpose or not.
>>
>>> +        }
>>> +    } else {
>>> +        ret = -ENXIO;
>>> +    }
>>> +
>>> +    kfree(obj);
>>> +
>>> +    return ret;
>>> +}
>>> +
>>> +static int dell_wmi_ddv_read_string(struct device *dev, enum 
>>> hwmon_sensor_types type, u32 attr,
>>> +                    int channel, const char **str)
>>> +{
>>> +    struct dell_wmi_ddv_data *data = dev_get_drvdata(dev);
>>> +
>>> +    switch (type) {
>>> +    case hwmon_fan:
>>> +        switch (attr) {
>>> +        case hwmon_fan_label:
>>> +            return dell_wmi_ddv_fan_read_string(data, channel, str);
>>> +        default:
>>> +            break;
>>> +        }
>>> +        break;
>>> +    case hwmon_temp:
>>> +        switch (attr) {
>>> +        case hwmon_temp_label:
>>> +            return dell_wmi_ddv_temp_read_string(data, channel, str);
>>> +        default:
>>> +            break;
>>> +        }
>>> +        break;
>>> +    default:
>>> +        break;
>>> +    }
>>> +
>>> +    return -EOPNOTSUPP;
>>> +}
>>> +
>>> +static const struct hwmon_ops dell_wmi_ddv_ops = {
>>> +    .is_visible = dell_wmi_ddv_is_visible,
>>> +    .read = dell_wmi_ddv_read,
>>> +    .read_string = dell_wmi_ddv_read_string,
>>> +};
>>> +
>>> +static struct hwmon_channel_info 
>>> *dell_wmi_ddv_channel_create(struct device *dev, u64 count,
>>> +                                  enum hwmon_sensor_types type,
>>> +                                  u32 config)
>>> +{
>>> +    struct combined_channel_info *cinfo;
>>> +    int i;
>>> +
>>> +    cinfo = devm_kzalloc(dev, struct_size(cinfo, config, count + 
>>> 1), GFP_KERNEL);
>>> +    if (!cinfo)
>>> +        return ERR_PTR(-ENOMEM);
>>> +
>>> +    cinfo->info.type = type;
>>> +    cinfo->info.config = cinfo->config;
>>> +
>>> +    for (i = 0; i < count; i++)
>>> +        cinfo->config[i] = config;
>>> +
>>> +    return &cinfo->info;
>>> +}
>>> +
>>> +static struct hwmon_channel_info *dell_wmi_ddv_channel_init(struct 
>>> wmi_device *wdev,
>>> +                                enum dell_ddv_method method,
>>> +                                size_t entry_size,
>>> +                                enum hwmon_sensor_types type,
>>> +                                u32 config)
>>> +{
>>> +    union acpi_object *obj;
>>> +    u64 count;
>>> +    int ret;
>>> +
>>> +    ret = dell_wmi_ddv_query_sensors(wdev, method, entry_size, 
>>> &obj, &count);
>>> +    if (ret < 0)
>>> +        return ERR_PTR(ret);
>>> +
>>> +    kfree(obj);
>>> +
>>> +    if (!count)
>>> +        return ERR_PTR(-ENODEV);
>>> +
>>> +    return dell_wmi_ddv_channel_create(&wdev->dev, count, type, 
>>> config);
>>> +}
>>> +
>>> +static int dell_wmi_ddv_hwmon_add(struct dell_wmi_ddv_data *data)
>>> +{
>>> +    struct wmi_device *wdev = data->wdev;
>>> +    struct combined_chip_info *cinfo;
>>> +    struct device *hdev;
>>> +    int index = 0;
>>> +    int ret;
>>> +
>>> +    if (!devres_open_group(&wdev->dev, dell_wmi_ddv_hwmon_add, 
>>> GFP_KERNEL))
>>> +        return -ENOMEM;
>>> +
>>> +    cinfo = devm_kzalloc(&wdev->dev, struct_size(cinfo, info, 4), 
>>> GFP_KERNEL);
>>> +    if (!cinfo) {
>>> +        ret = -ENOMEM;
>>> +
>>> +        goto err_release;
>>> +    }
>>> +
>>> +    cinfo->chip.ops = &dell_wmi_ddv_ops;
>>> +    cinfo->chip.info = cinfo->info;
>>> +
>>> +    cinfo->info[index] = dell_wmi_ddv_channel_create(&wdev->dev, 1, 
>>> hwmon_chip,
>>> +                             HWMON_C_REGISTER_TZ);
>>> +
>>> +    if (IS_ERR(cinfo->info[index])) {
>>> +        ret = PTR_ERR(cinfo->info[index]);
>>> +
>>> +        goto err_release;
>>> +    }
>>> +
>>> +    index++;
>>> +
>>> +    cinfo->info[index] = dell_wmi_ddv_channel_init(wdev, 
>>> DELL_DDV_FAN_SENSOR_INFORMATION,
>>> +                               sizeof(struct fan_sensor_entry), 
>>> hwmon_fan,
>>> +                               (HWMON_F_INPUT | HWMON_F_LABEL));
>>> +    if (!IS_ERR(cinfo->info[index]))
>>> +        index++;
>>> +
>>> +    cinfo->info[index] = dell_wmi_ddv_channel_init(wdev, 
>>> DELL_DDV_THERMAL_SENSOR_INFORMATION,
>>> +                               sizeof(struct thermal_sensor_entry),
>>> +                               hwmon_temp, (HWMON_T_INPUT | 
>>> HWMON_T_MIN |
>>> +                               HWMON_T_MAX | HWMON_T_LABEL));
>>> +    if (!IS_ERR(cinfo->info[index]))
>>> +        index++;
>>> +
>>> +    if (!index) {
>>> +        ret = -ENODEV;
>>> +
>>> +        goto err_release;
>>> +    }
>>> +
>>> +    cinfo->info[index] = NULL;
>>> +
>>> +    hdev = devm_hwmon_device_register_with_info(&wdev->dev, 
>>> "dell_ddv", data, &cinfo->chip,
>>> +                            NULL);
>>> +    if (IS_ERR(hdev)) {
>>> +        ret = PTR_ERR(hdev);
>>> +
>>> +        goto err_release;
>>> +    }
>>> +
>>> +    devres_close_group(&wdev->dev, dell_wmi_ddv_hwmon_add);
>>> +
>>> +    return 0;
>>> +
>>> +err_release:
>>> +    devres_release_group(&wdev->dev, dell_wmi_ddv_hwmon_add);
>>> +
>>> +    return ret;
>>> +}
>>> +
>>>   static int dell_wmi_ddv_battery_index(struct acpi_device 
>>> *acpi_dev, u32 *index)
>>>   {
>>>       const char *uid_str;
>>> @@ -370,7 +795,15 @@ static int dell_wmi_ddv_probe(struct wmi_device 
>>> *wdev, const void *context)
>>>
>>>       dell_wmi_ddv_debugfs_init(wdev);
>>>
>>> -    return dell_wmi_ddv_battery_add(data);
>>> +    ret = dell_wmi_ddv_hwmon_add(data);
>>> +    if (ret < 0)
>>> +        dev_dbg(&wdev->dev, "Unable to register hwmon interface: 
>>> %d\n", ret);
>>> +
>>> +    ret = dell_wmi_ddv_battery_add(data);
>>> +    if (ret < 0)
>>> +        dev_dbg(&wdev->dev, "Unable to register acpi battery hook: 
>>> %d\n", ret);
>>> +
>> This used to be an error, but no longer is. Not my call to make
>> if this is acceptable, just pointing it out.
>
> I decided to not treat the battery hook as essential function anymore 
> because
> the battery hook and hwmon functionality are more or less disconnected 
> from
> each other, so having the driver abort probing just because one 
> functionality
> could not be initialized seemed unreasonable to me.
>
> I already thought about putting the battery hook and hwmon 
> functionality into
> separate drivers, with the main driver registering a MFD device or 
> something similar.
> Because apart from some generic routines, both functions are not 
> connected in any way.
>
> Is it acceptable to split the driver for such a thing?
>
> Armin Wolf
>
Any thoughts about this? Otherwise i will just use conditionals.

Armin Wolf

>>> +    return 0;
>>>   }
>>>
>>>   static const struct wmi_device_id dell_wmi_ddv_id_table[] = {
>>> -- 
>>> 2.30.2
>>>

Powered by blists - more mailing lists