From: Chu Lin <linchuyuan@google.com>
To: Chu Lin <linchuyuan@google.com>,
jdelvare@suse.com, Guenter Roeck <linux@roeck-us.net>,
linux-kernel@vger.kernel.org, linux-hwmon@vger.kernel.org,
Qiong Wang <qiongwang@google.com>,
Zhongqi Li <zhongqil@google.com>,
Jason Ling <jasonling@google.com>,
Kais Belgaied <belgaied@google.com>
Subject: Re: [PATCH] hwmon: pmbus: max20730: adjust the vout reading given voltage divider
Date: Thu, 10 Sep 2020 10:20:15 -0700 [thread overview]
Message-ID: <CAKCA56CVHDDk0FDuda143L=_OXQ5JyWA=joKtKq-ok+R6JSYRg@mail.gmail.com> (raw)
In-Reply-To: <20200910170910.1990578-1-linchuyuan@google.com>
The same patch got sent twice. Please, discard this one.
Thanks,
Chu
On Thu, Sep 10, 2020 at 10:09 AM Chu Lin <linchuyuan@google.com> wrote:
>
> Problem:
> We use voltage dividers so that the voltage presented at the voltage
> sense pins is confusing. We might need to convert these readings to more
> meaningful readings given the voltage divider.
>
> Solution:
> Read the voltage divider resistance from dts and convert the voltage
> reading to a more meaningful reading.
>
> Testing:
> max20730 with voltage divider
>
> Signed-off-by: Chu Lin <linchuyuan@google.com>
> ---
> drivers/hwmon/pmbus/max20730.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/drivers/hwmon/pmbus/max20730.c b/drivers/hwmon/pmbus/max20730.c
> index c0bb05487e0e..4b56810fa894 100644
> --- a/drivers/hwmon/pmbus/max20730.c
> +++ b/drivers/hwmon/pmbus/max20730.c
> @@ -29,6 +29,7 @@ struct max20730_data {
> struct pmbus_driver_info info;
> struct mutex lock; /* Used to protect against parallel writes */
> u16 mfr_devset1;
> + u32 vout_voltage_divider[2];
> };
>
> #define to_max20730_data(x) container_of(x, struct max20730_data, info)
> @@ -111,6 +112,12 @@ static int max20730_read_word_data(struct i2c_client *client, int page,
> max_c = max_current[data->id][(data->mfr_devset1 >> 5) & 0x3];
> ret = val_to_direct(max_c, PSC_CURRENT_OUT, info);
> break;
> + case PMBUS_READ_VOUT:
> + ret = pmbus_read_word_data(client, page, phase, reg);
> + if (data->vout_voltage_divider[0] && data->vout_voltage_divider[1])
> + ret = DIV_ROUND_CLOSEST(ret * data->vout_voltage_divider[1],
> + data->vout_voltage_divider[0]);
> + break;
> default:
> ret = -ENODATA;
> break;
> @@ -329,6 +336,15 @@ static int max20730_probe(struct i2c_client *client,
> data->id = chip_id;
> mutex_init(&data->lock);
> memcpy(&data->info, &max20730_info[chip_id], sizeof(data->info));
> + if (of_property_read_u32_array(client->dev.of_node, "vout-voltage-divider",
> + data->vout_voltage_divider,
> + ARRAY_SIZE(data->vout_voltage_divider)) != 0)
> + memset(data->vout_voltage_divider, 0, sizeof(data->vout_voltage_divider));
> + if (data->vout_voltage_divider[1] < data->vout_voltage_divider[0]) {
> + dev_err(dev,
> + "The total resistance of voltage divider is less than output resistance\n");
> + return -ENODEV;
> + }
>
> ret = i2c_smbus_read_word_data(client, MAX20730_MFR_DEVSET1);
> if (ret < 0)
> --
> 2.28.0.526.ge36021eeef-goog
>
next prev parent reply other threads:[~2020-09-10 17:21 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-10 17:09 [PATCH] hwmon: pmbus: max20730: adjust the vout reading given voltage divider Chu Lin
2020-09-10 17:20 ` Chu Lin [this message]
-- strict thread matches above, loose matches on Subject: below --
2020-09-10 17:08 Chu Lin
2020-09-10 19:05 ` Guenter Roeck
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