From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bh-25.webhostbox.net (bh-25.webhostbox.net. [208.91.199.152]) by gmr-mx.google.com with ESMTPS id ht1si431186igb.1.2016.01.22.10.51.02 for (version=TLS1 cipher=AES128-SHA bits=128/128); Fri, 22 Jan 2016 10:51:02 -0800 (PST) Subject: [rtc-linux] Re: [PATCH v2] rtc: rtc-ds1307: add temperature sensor support for ds3231 To: Akinobu Mita , rtc-linux@googlegroups.com References: <1453485441-11667-1-git-send-email-akinobu.mita@gmail.com> Cc: Alessandro Zummo , Alexandre Belloni , Jean Delvare , lm-sensors@lm-sensors.org From: Guenter Roeck Message-ID: <56A27A11.1010805@roeck-us.net> Date: Fri, 22 Jan 2016 10:50:57 -0800 MIME-Version: 1.0 In-Reply-To: <1453485441-11667-1-git-send-email-akinobu.mita@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Reply-To: rtc-linux@googlegroups.com List-ID: List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , On 01/22/2016 09:57 AM, Akinobu Mita wrote: > DS3231 has the temperature registers with a resolution of 0.25 > degree celsius. This enables to get the value through hwmon. > > # cat /sys/class/i2c-adapter/i2c-2/2-0068/hwmon/hwmon0/temp1_input > 21000 > > Signed-off-by: Akinobu Mita > Cc: Alessandro Zummo > Cc: Alexandre Belloni > Cc: rtc-linux@googlegroups.com > Cc: Jean Delvare > Cc: Guenter Roeck > Cc: lm-sensors@lm-sensors.org > --- > * v2 > - convert to use hwmon framework, suggested by Alexandre Belloni > > drivers/rtc/rtc-ds1307.c | 122 +++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 122 insertions(+) > > diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c > index aa705bb..e0d4ce5 100644 > --- a/drivers/rtc/rtc-ds1307.c > +++ b/drivers/rtc/rtc-ds1307.c > @@ -19,6 +19,9 @@ > #include > #include > #include > +#include > +#include > +#include > > /* > * We can't determine type by probing, but if we expect pre-Linux code > @@ -75,6 +78,7 @@ enum ds_type { > # define DS1337_BIT_nEOSC 0x80 > # define DS1339_BIT_BBSQI 0x20 > # define DS3231_BIT_BBSQW 0x40 /* same as BBSQI */ > +# define DS3231_BIT_CONV 0x20 > # define DS1337_BIT_RS2 0x10 > # define DS1337_BIT_RS1 0x08 > # define DS1337_BIT_INTCN 0x04 > @@ -89,6 +93,7 @@ enum ds_type { > # define DS1340_BIT_OSF 0x80 > #define DS1337_REG_STATUS 0x0f > # define DS1337_BIT_OSF 0x80 > +# define DS3231_BIT_BSY 0x04 > # define DS1337_BIT_A2I 0x02 > # define DS1337_BIT_A1I 0x01 > #define DS1339_REG_ALARM1_SECS 0x07 > @@ -851,6 +856,121 @@ out: > return; > } > > +/*----------------------------------------------------------------------*/ > + > +#if IS_ENABLED(CONFIG_HWMON) > + > +/* > + * Temperature sensor support for ds3231 devices. > + */ > + > +#define DS3231_REG_TEMPERATURE 0x11 > + > +static ssize_t ds3231_hwmon_show_temp(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct ds1307 *ds1307 = dev_get_drvdata(dev); space instead of tab ? > + struct i2c_client *client = ds1307->client; > + u8 temp_buf[2]; > + s16 temp; > + int control; > + int status; > + s32 ret; > + unsigned long timeout; > + > + status = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS); > + if (status < 0) > + return status; > + > + /* > + * Start user-initiated temperature conversion > + */ > + if (!(status & DS3231_BIT_BSY)) { > + struct mutex *lock = &ds1307->rtc->ops_lock; > + > + mutex_lock(lock); > + > + control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL); > + if (control < 0) { > + mutex_unlock(lock); > + return control; > + } > + ret = i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, > + control | DS3231_BIT_CONV); > + if (ret) > + return ret; > + Leaks the lock. It might be better to define error abort handling with a label. > + mutex_unlock(lock); Another conversion could be initiated at this point. It might be better to keep the lock until the sequence is complete. > + > + /* > + * A user-initiated temperature conversion does not affect > + * the BSY bit for approximately 2ms. > + */ > + usleep_range(2000, 3000); > + } > + > + /* > + * Wait until the conversion is finished > + */ > + timeout = jiffies + HZ; Can it really take that long ? Datashet gives a maximum of 200 ms. > + > + do { > + control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL); > + if (control < 0) > + return control; > + if (!(control & DS3231_BIT_CONV)) > + break; > + if (time_after(jiffies, timeout)) > + return -EIO; > + usleep_range(2000, 3000); > + } while (1); > + > + ret = ds1307->read_block_data(ds1307->client, DS3231_REG_TEMPERATURE, > + sizeof(temp_buf), temp_buf); I am not sure if using read_block_data() is worth the complexity. Two individual calls to i2c_smbus_read_byte_data() seem to be much more straightforward. > + if (ret < 0) > + return ret; > + if (ret != sizeof(temp_buf)) > + return -EIO; [ ... and would also avoid the odd -EIO here ] Please consider just relying on internal/automatic conversions. True, those only occur every 64 seconds, but given the accuracy of +- 3 degrees C I don't think the gain of an immediate conversion outweighs the additional code complexity and the resulting delay. > + > + /* > + * Temperature is represented as a 10-bit code with a resolution of > + * 0.25 degree celsius and encoded in two's complement format. > + */ > + temp = (temp_buf[0] << 8) | temp_buf[1]; > + temp >>= 6; > + > + return sprintf(buf, "%d\n", temp * 250); > +} > +static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ds3231_hwmon_show_temp, > + NULL, 0); > + > +static struct attribute *ds3231_hwmon_attrs[] = { > + &sensor_dev_attr_temp1_input.dev_attr.attr, > + NULL, > +}; > +ATTRIBUTE_GROUPS(ds3231_hwmon); > + > +static int ds1307_hwmon_register(struct ds1307 *ds1307) > +{ > + if (ds1307->type != ds_3231) > + return 0; > + > + devm_hwmon_device_register_with_groups(&ds1307->client->dev, > + ds1307->client->name, > + ds1307, ds3231_hwmon_groups); > + No error check ? It might make sense to not fail registration if this call fails, but maybe a warning in the console log would make sense. > + return 0; > +} > + > +#else > + > +static int ds1307_hwmon_register(struct ds1307 *ds1307) > +{ > + return 0; > +} > + > +#endif > + > static int ds1307_probe(struct i2c_client *client, > const struct i2c_device_id *id) > { > @@ -1191,6 +1311,8 @@ read_rtc: > } > } > > + ds1307_hwmon_register(ds1307); > + > return 0; > > exit: > -- -- You received this message because you are subscribed to "rtc-linux". Membership options at http://groups.google.com/group/rtc-linux . Please read http://groups.google.com/group/rtc-linux/web/checklist before submitting a driver. --- You received this message because you are subscribed to the Google Groups "rtc-linux" group. To unsubscribe from this group and stop receiving emails from it, send an email to rtc-linux+unsubscribe@googlegroups.com. For more options, visit https://groups.google.com/d/optout.