From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751976AbaK3Tps (ORCPT ); Sun, 30 Nov 2014 14:45:48 -0500 Received: from bh-25.webhostbox.net ([208.91.199.152]:51544 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751614AbaK3Tpr (ORCPT ); Sun, 30 Nov 2014 14:45:47 -0500 Message-ID: <547B739D.7040405@roeck-us.net> Date: Sun, 30 Nov 2014 11:44:29 -0800 From: Guenter Roeck User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Bartosz Golaszewski CC: LKML , Benoit Cousson , Patrick Titiano , LM Sensors , Jean Delvare Subject: Re: [PATCH v2 2/5] hwmon: ina2xx: make shunt resistance configurable at run-time References: <1417082350-23470-1-git-send-email-bgolaszewski@baylibre.com> <1417082350-23470-3-git-send-email-bgolaszewski@baylibre.com> In-Reply-To: <1417082350-23470-3-git-send-email-bgolaszewski@baylibre.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-CTCH-PVer: 0000001 X-CTCH-Spam: Unknown X-CTCH-VOD: Unknown X-CTCH-Flags: 0 X-CTCH-RefID: str=0001.0A020201.547B73EA.00E4,ss=1,re=0.001,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-CTCH-Score: 0.001 X-CTCH-ScoreCust: 0.000 X-CTCH-Rules: C_4847, X-CTCH-SenderID: linux@roeck-us.net X-CTCH-SenderID-Flags: 0 X-CTCH-SenderID-TotalMessages: 7 X-CTCH-SenderID-TotalSpam: 0 X-CTCH-SenderID-TotalSuspected: 0 X-CTCH-SenderID-TotalConfirmed: 0 X-CTCH-SenderID-TotalBulk: 0 X-CTCH-SenderID-TotalVirus: 0 X-CTCH-SenderID-TotalRecipients: 0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: mailgid no entry from get_relayhosts_entry X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/27/2014 01:59 AM, Bartosz Golaszewski wrote: > The shunt resistance can only be set via platform_data or device tree. This > isn't suitable for devices in which the shunt resistance can change/isn't > known at boot-time. > > Add a sysfs attribute that allows to read and set the shunt resistance. > > Signed-off-by: Bartosz Golaszewski > --- > drivers/hwmon/ina2xx.c | 62 +++++++++++++++++++++++++++++++++++++++++++++----- > 1 file changed, 56 insertions(+), 6 deletions(-) > > diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c > index 0a6b60f..341da67 100644 > --- a/drivers/hwmon/ina2xx.c > +++ b/drivers/hwmon/ina2xx.c > @@ -51,6 +51,8 @@ > #define INA226_ALERT_LIMIT 0x07 > #define INA226_DIE_ID 0xFF > > +/* shunt resistor sysfs attribute index */ > +#define INA2XX_RSHUNT 0x8 > > /* register count */ > #define INA219_REGISTERS 6 > @@ -65,6 +67,9 @@ > /* worst case is 68.10 ms (~14.6Hz, ina219) */ > #define INA2XX_CONVERSION_RATE 15 > > +/* default shunt resistance */ > +#define INA2XX_RSHUNT_DEFAULT 10000 > + > enum ina2xx_ids { ina219, ina226 }; > > struct ina2xx_config { > @@ -87,6 +92,8 @@ struct ina2xx_data { > > int kind; > u16 regs[INA2XX_MAX_REGISTERS]; > + > + long rshunt; > }; > > static const struct ina2xx_config ina2xx_config[] = { > @@ -110,6 +117,11 @@ static const struct ina2xx_config ina2xx_config[] = { > }, > }; > > +static u16 ina2xx_calibration_val(const struct ina2xx_data *data) > +{ > + return data->config->calibration_factor / data->rshunt; > +} > + > static struct ina2xx_data *ina2xx_update_device(struct device *dev) > { > struct ina2xx_data *data = dev_get_drvdata(dev); > @@ -164,6 +176,9 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 reg) > /* signed register, LSB=1mA (selected), in mA */ > val = (s16)data->regs[reg]; > break; > + case INA2XX_RSHUNT: > + val = data->rshunt; > + break; That doesn't make sense. You neither read the current shunt resistor value with update_device, nor use the register value to calculate the programmed shunt resistor value. Just define a separate show function which reports rshunt as configured. A better alternative would be to actually _read_ and report rshunt as programmed into the chip. Otherwise you'll get the "old" value of rshunt even if the chip was, as your use case suggests, pulled and re-inserted. > default: > /* programmer goofed */ > WARN_ON_ONCE(1); > @@ -187,6 +202,35 @@ static ssize_t ina2xx_show_value(struct device *dev, > ina2xx_get_value(data, attr->index)); > } > > +static ssize_t ina2xx_set_shunt(struct device *dev, > + struct device_attribute *da, > + const char *buf, size_t count) > +{ > + struct ina2xx_data *data = ina2xx_update_device(dev); > + long val; This should be unsigned long since you now use kstrtoul. > + int status; > + > + if (IS_ERR(data)) > + return PTR_ERR(data); > + > + status = kstrtoul(buf, 10, &val); > + if (status < 0) > + return status; This will accept a value of 0xffffffff which is then converted into -1 since data->rshunt is defined as long. > + > + if (val == 0) > + return -EINVAL; > + > + mutex_lock(&data->update_lock); > + data->rshunt = val; > + status = i2c_smbus_write_word_swapped(data->client, INA2XX_CALIBRATION, > + ina2xx_calibration_val(data)); > + mutex_unlock(&data->update_lock); > + if (status < 0) > + return status; > + > + return count; > +} > + > /* shunt voltage */ > static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ina2xx_show_value, NULL, > INA2XX_SHUNT_VOLTAGE); > @@ -203,12 +247,17 @@ static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ina2xx_show_value, NULL, > static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, ina2xx_show_value, NULL, > INA2XX_POWER); > > +/* shunt resistance */ > +static SENSOR_DEVICE_ATTR(shunt_resistor, S_IRUGO | S_IWUSR | S_IWGRP, This will have to be S_IRUGO | S_IWUSR. We don't permit group writes. > + ina2xx_show_value, ina2xx_set_shunt, INA2XX_RSHUNT); > + > /* pointers to created device attributes */ > static struct attribute *ina2xx_attrs[] = { > &sensor_dev_attr_in0_input.dev_attr.attr, > &sensor_dev_attr_in1_input.dev_attr.attr, > &sensor_dev_attr_curr1_input.dev_attr.attr, > &sensor_dev_attr_power1_input.dev_attr.attr, > + &sensor_dev_attr_shunt_resistor.dev_attr.attr, > NULL, > }; > ATTRIBUTE_GROUPS(ina2xx); > @@ -221,7 +270,6 @@ static int ina2xx_probe(struct i2c_client *client, > struct device *dev = &client->dev; > struct ina2xx_data *data; > struct device *hwmon_dev; > - long shunt = 10000; /* default shunt value 10mOhms */ > u32 val; > int ret; > > @@ -234,13 +282,15 @@ static int ina2xx_probe(struct i2c_client *client, > > if (dev_get_platdata(dev)) { > pdata = dev_get_platdata(dev); > - shunt = pdata->shunt_uohms; > + data->rshunt = pdata->shunt_uohms; > } else if (!of_property_read_u32(dev->of_node, > "shunt-resistor", &val)) { > - shunt = val; > + data->rshunt = val; > + } else { > + data->rshunt = INA2XX_RSHUNT_DEFAULT; > } > > - if (shunt <= 0) > + if (data->rshunt <= 0) > return -ENODEV; > > /* set the device type */ > @@ -260,7 +310,7 @@ static int ina2xx_probe(struct i2c_client *client, > * (equation 13 in datasheet). > */ > ret = i2c_smbus_write_word_swapped(client, INA2XX_CALIBRATION, > - data->config->calibration_factor / shunt); > + ina2xx_calibration_val(data)); > if (ret < 0) { > dev_err(dev, > "error writing to the calibration register: %d", ret); > @@ -276,7 +326,7 @@ static int ina2xx_probe(struct i2c_client *client, > return PTR_ERR(hwmon_dev); > > dev_info(dev, "power monitor %s (Rshunt = %li uOhm)\n", > - id->name, shunt); > + id->name, data->rshunt); > > return 0; > } >