Re: [PATCH] adm1275: support PMBUS_VIRT_*_SAMPLES

Guenter Roeck
2019-05-29T12:17:53Z

On 5/29/19 12:11 AM, Adamski, Krzysztof (Nokia - PL/Wroclaw) wrote:
> On Tue, May 28, 2019 at 12:46:52PM -0700, Guenter Roeck wrote:
>> On Fri, May 24, 2019 at 12:49:13PM +0000, Adamski, Krzysztof (Nokia - PL/Wroclaw) wrote:
>>> The device supports setting the number of samples for averaging the
>>> measurements. There are two separate settings - PWR_AVG for averaging
>>> PIN and VI_AVG for averaging VIN/VAUX/IOUT, both being part of
>>> PMON_CONFIG register. The values are stored as exponent of base 2 of the
>>> actual number of samples that will be taken.
>>>
>>> Signed-off-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
>>> ---
>>> drivers/hwmon/pmbus/adm1275.c | 68 ++++++++++++++++++++++++++++++++++-
>>> 1 file changed, 67 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/hwmon/pmbus/adm1275.c b/drivers/hwmon/pmbus/adm1275.c
>>> index f569372c9204..4efe1a9df563 100644
>>> --- a/drivers/hwmon/pmbus/adm1275.c
>>> +++ b/drivers/hwmon/pmbus/adm1275.c
>>> @@ -23,6 +23,8 @@
>>> #include <linux/slab.h>
>>> #include <linux/i2c.h>
>>> #include <linux/bitops.h>
>>> +#include <linux/bitfield.h>
>>> +#include <linux/log2.h>
>>> #include "pmbus.h"
>>>
>>> enum chips { adm1075, adm1272, adm1275, adm1276, adm1278, adm1293, adm1294 };
>>> @@ -78,6 +80,10 @@ enum chips { adm1075, adm1272, adm1275, adm1276, adm1278, adm1293, adm1294 };
>>> #define ADM1075_VAUX_OV_WARN BIT(7)
>>> #define ADM1075_VAUX_UV_WARN BIT(6)
>>>
>>> +#define ADM1275_PWR_AVG_MASK GENMASK(13, 11)
>>> +#define ADM1275_VI_AVG_MASK GENMASK(10, 8)
>>> +#define ADM1275_SAMPLES_AVG_MAX 128
>>> +
>>> struct adm1275_data {
>>> int id;
>>> bool have_oc_fault;
>>> @@ -90,6 +96,7 @@ struct adm1275_data {
>>> bool have_pin_max;
>>> bool have_temp_max;
>>> struct pmbus_driver_info info;
>>> + struct mutex lock;
>>> };
>>>
>>> #define to_adm1275_data(x) container_of(x, struct adm1275_data, info)
>>> @@ -164,6 +171,38 @@ static const struct coefficients adm1293_coefficients[] = {
>>> [18] = { 7658, 0, -3 }, /* power, 21V, irange200 */
>>> };
>>>
>>> +static inline int adm1275_read_pmon_config(struct i2c_client *client, u64 mask)
>>
>> Why is the mask passed through as u64 ?
>
> Good point. I used u64 as this is the type used by bitfield machinery
> under the hood but I agree it doesn't make sense and is even confusing
> to have this in the function prototype as we are using this to mask 16
> bit word anyways. I will fix that in v2. I am gonna have to cast the ret
> to u16 when passing to FIELD_GET() to make sure the __BF_FIELD_CHECK is
> not complaining (since it is signed right now), though.
>

Not sure I understand what you are talking about. FIELD_GET() uses typeof().
FIELD_GET() is used by other callers even with u8 and without any typecasts.
Why would it be a problem here ?

>>
>>> +{
>>> + int ret;
>>> +
>>> + ret = i2c_smbus_read_word_data(client, ADM1275_PMON_CONFIG);
>>> + if (ret < 0)
>>> + return ret;
>>> +
>>> + return FIELD_GET(mask, ret);
>>> +}
>>> +
>>> +static inline int adm1275_write_pmon_config(struct i2c_client *client, u64 mask,
>>> + u16 word)
>>> +{
>>> + const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
>>> + struct adm1275_data *data = to_adm1275_data(info);
>>> + int ret;
>>> +
>>> + mutex_lock(&data->lock);
>>
>> Why is another lock on top of the lock provided by the pmbus core required ?
>>
>
> Good point, I was considering if I should instead add mutex_lock on
> update_lock in the pmbus_set_samples() function inside of pmbus_core.c
> instead (as this function is missing it) but figured that not all
> devices will need that (lm25066 didn't) so it might be a waste in most
> cases. But this may be cleaner approach indeed.
>
> Is this what you mean or there is some other lock I missed?
>
pmbus_set_samples() should set the pmbus lock. That was missed when
the function was added.

>>> + ret = i2c_smbus_read_word_data(client, ADM1275_PMON_CONFIG);
>>> + if (ret < 0) {
>>> + mutex_unlock(&data->lock);
>>> + return ret;
>>> + }
>>> +
>>> + word = FIELD_PREP(mask, word) | (ret & ~mask);
>>> + ret = i2c_smbus_write_word_data(client, ADM1275_PMON_CONFIG, word);
>>> + mutex_unlock(&data->lock);
>>> +
>>> + return ret;
>>> +}
>>> +
>>> static int adm1275_read_word_data(struct i2c_client *client, int page, int reg)
>>> {
>>> const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
>>> @@ -242,6 +281,19 @@ static int adm1275_read_word_data(struct i2c_client *client, int page, int reg)
>>> if (!data->have_temp_max)
>>> return -ENXIO;
>>> break;
>>> + case PMBUS_VIRT_POWER_SAMPLES:
>>> + ret = adm1275_read_pmon_config(client, ADM1275_PWR_AVG_MASK);
>>> + if (ret < 0)
>>> + break;
>>> + ret = 1 << ret;
>>
>> ret = BIT(ret);
>>
>
> I intentionally used the "raw" left shift to make it more obvious this
> is pow2 arithmetic operation and an direct inverse to the ilog2() used
> on write counterpart. This is also consistent with what I used in
> lm25066.c driver not long time ago.
>
> I don't have strong preference but this is my reasoning. So do you still
> think it is better to use BIT() macro instead?
>

I don't think that is a good rationale, but I'll let it go.

Guenter

>>> + break;
>>> + case PMBUS_VIRT_IN_SAMPLES:
>>> + case PMBUS_VIRT_CURR_SAMPLES:
>>> + ret = adm1275_read_pmon_config(client, ADM1275_VI_AVG_MASK);
>>> + if (ret < 0)
>>> + break;
>>> + ret = 1 << ret;
>>
>> ret = BIT(ret);
>>
>>> + break;
>>> default:
>>> ret = -ENODATA;
>>> break;
>>> @@ -286,6 +338,17 @@ static int adm1275_write_word_data(struct i2c_client *client, int page, int reg,
>>> case PMBUS_VIRT_RESET_TEMP_HISTORY:
>>> ret = pmbus_write_word_data(client, 0, ADM1278_PEAK_TEMP, 0);
>>> break;
>>> + case PMBUS_VIRT_POWER_SAMPLES:
>>> + word = clamp_val(word, 1, ADM1275_SAMPLES_AVG_MAX);
>>> + ret = adm1275_write_pmon_config(client, ADM1275_PWR_AVG_MASK,
>>> + ilog2(word));
>>> + break;
>>> + case PMBUS_VIRT_IN_SAMPLES:
>>> + case PMBUS_VIRT_CURR_SAMPLES:
>>> + word = clamp_val(word, 1, ADM1275_SAMPLES_AVG_MAX);
>>> + ret = adm1275_write_pmon_config(client, ADM1275_VI_AVG_MASK,
>>> + ilog2(word));
>>> + break;
>>> default:
>>> ret = -ENODATA;
>>> break;
>>> @@ -422,6 +485,8 @@ static int adm1275_probe(struct i2c_client *client,
>>> if (!data)
>>> return -ENOMEM;
>>>
>>> + mutex_init(&data->lock);
>>> +
>>> if (of_property_read_u32(client->dev.of_node,
>>> "shunt-resistor-micro-ohms", &shunt))
>>> shunt = 1000; /* 1 mOhm if not set via DT */
>>> @@ -439,7 +504,8 @@ static int adm1275_probe(struct i2c_client *client,
>>> info->format[PSC_CURRENT_OUT] = direct;
>>> info->format[PSC_POWER] = direct;
>>> info->format[PSC_TEMPERATURE] = direct;
>>> - info->func[0] = PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT;
>>> + info->func[0] = PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
>>> + PMBUS_HAVE_SAMPLES;
>>>
>>> info->read_word_data = adm1275_read_word_data;
>>> info->read_byte_data = adm1275_read_byte_data;
>>> --
>>> 2.20.1
>>>
>