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  • * Re: [PATCH] hwmon: Add LTC2471/LTC2473 driver
       [not found] <1498733135-4729-1-git-send-email-mike.looijmans@topic.nl>
       [not found] ` <1498738434-18252-1-git-send-email-mike.looijmans@topic.nl>
@ 2017-06-29 13:34 ` Guenter Roeck
  2017-07-01  9:58   ` Jonathan Cameron
  1 sibling, 1 reply; 9+ messages in thread
From: Guenter Roeck @ 2017-06-29 13:34 UTC (permalink / raw)
  To: Mike Looijmans, linux-hwmon
  Cc: linux-kernel, Jonathan Cameron, linux-iio, jdelvare

On 06/29/2017 03:45 AM, Mike Looijmans wrote:
> The LTC2741 and LTC2473 are single voltage monitoring chips. The LTC2473
> is similar to the LTC2471 but outputs a signed differential value.
> 
> Datasheet:
>    http://cds.linear.com/docs/en/datasheet/24713fb.pdf
> 
> Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>

Hi Mike,

that looks like a perfect candidate for an iio driver, since its use is
not limited to hardware monitoring, it has a high sample rate, and it
doesn't have limit registers or actions.

Jonathan, what do you think ?

Thanks,
Guenter

> ---
>   drivers/hwmon/Kconfig   |  10 ++++
>   drivers/hwmon/Makefile  |   1 +
>   drivers/hwmon/ltc2471.c | 127 ++++++++++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 138 insertions(+)
>   create mode 100644 drivers/hwmon/ltc2471.c
> 
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index fbde226..c9a2a87 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -673,6 +673,16 @@ config SENSORS_LINEAGE
>   	  This driver can also be built as a module.  If so, the module
>   	  will be called lineage-pem.
>   
> +config SENSORS_LTC2471
> +	tristate "Linear Technology LTC2471 and LTC2473"
> +	depends on I2C
> +	help
> +	  If you say yes here you get support for Linear Technology LTC2471
> +	  and LTC2473 voltage monitors.
> +
> +	  This driver can also be built as a module. If so, the module will
> +	  be called ltc2471.
> +
>   config SENSORS_LTC2945
>   	tristate "Linear Technology LTC2945"
>   	depends on I2C
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 58cc3ac..6f60fe7 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -99,6 +99,7 @@ obj-$(CONFIG_SENSORS_LM93)	+= lm93.o
>   obj-$(CONFIG_SENSORS_LM95234)	+= lm95234.o
>   obj-$(CONFIG_SENSORS_LM95241)	+= lm95241.o
>   obj-$(CONFIG_SENSORS_LM95245)	+= lm95245.o
> +obj-$(CONFIG_SENSORS_LTC2471)	+= ltc2471.o
>   obj-$(CONFIG_SENSORS_LTC2945)	+= ltc2945.o
>   obj-$(CONFIG_SENSORS_LTC2990)	+= ltc2990.o
>   obj-$(CONFIG_SENSORS_LTC4151)	+= ltc4151.o
> diff --git a/drivers/hwmon/ltc2471.c b/drivers/hwmon/ltc2471.c
> new file mode 100644
> index 0000000..17eaad8
> --- /dev/null
> +++ b/drivers/hwmon/ltc2471.c
> @@ -0,0 +1,127 @@
> +/*
> + * Driver for Linear Technology LTC2471 and LTC2473 voltage monitors
> + * The LTC2473 is identical to the 2471, but reports a differential signal.
> + *
> + * Copyright (C) 2017 Topic Embedded Products
> + * Author: Mike Looijmans <mike.looijmans@topic.nl>
> + *
> + * License: GPLv2
> + */
> +
> +#include <linux/err.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/i2c.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +
> +enum chips {
> +	ltc2471,
> +	ltc2473
> +};
> +
> +struct ltc2471_data {
> +	struct i2c_client *i2c;
> +	bool differential;
> +};
> +
> +/* Reference voltage is 1.25V */
> +#define LTC2471_VREF 1250
> +
> +/* Read two bytes from the I2C bus to obtain the ADC result */
> +static int ltc2471_get_value(struct i2c_client *i2c)
> +{
> +	int ret;
> +	__be16 buf;
> +
> +	ret = i2c_master_recv(i2c, (char *)&buf, 2);
> +	if (ret < 0)
> +		return ret;
> +	if (ret != 2)
> +		return -EIO;
> +
> +	/* MSB first */
> +	return be16_to_cpu(buf);
> +}
> +
> +static ssize_t ltc2471_show_value(struct device *dev,
> +				  struct device_attribute *da, char *buf)
> +{
> +	struct ltc2471_data *data = dev_get_drvdata(dev);
> +	int value;
> +
> +	value = ltc2471_get_value(data->i2c);
> +	if (unlikely(value < 0))
> +		return value;
> +
> +	if (data->differential)
> +		/* Ranges from -VREF to +VREF with "0" at 0x8000 */
> +		value = ((s32)LTC2471_VREF * (s32)(value - 0x8000)) >> 15;
> +	else
> +		/* Ranges from 0 to +VREF */
> +		value = ((u32)LTC2471_VREF * (u32)value) >> 16;
> +
> +	return snprintf(buf, PAGE_SIZE, "%d\n", value);
> +}
> +
> +static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ltc2471_show_value, NULL, 0);
> +
> +static struct attribute *ltc2471_attrs[] = {
> +	&sensor_dev_attr_in0_input.dev_attr.attr,
> +	NULL
> +};
> +
> +ATTRIBUTE_GROUPS(ltc2471);
> +
> +static int ltc2471_i2c_probe(struct i2c_client *i2c,
> +			     const struct i2c_device_id *id)
> +{
> +	int ret;
> +	struct device *hwmon_dev;
> +	struct ltc2471_data *data;
> +
> +	if (!i2c_check_functionality(i2c->adapter, I2C_FUNC_I2C))
> +		return -ENODEV;
> +
> +	data = devm_kzalloc(&i2c->dev, sizeof(struct ltc2471_data), GFP_KERNEL);
> +	if (unlikely(!data))
> +		return -ENOMEM;
> +
> +	data->i2c = i2c;
> +	data->differential = (id->driver_data == ltc2473);
> +
> +	/* Trigger once to start conversion and check if chip is there */
> +	ret = ltc2471_get_value(i2c);
> +	if (ret < 0) {
> +		dev_err(&i2c->dev, "Cannot read from device.\n");
> +		return ret;
> +	}
> +
> +	hwmon_dev = devm_hwmon_device_register_with_groups(&i2c->dev,
> +							   i2c->name,
> +							   data,
> +							   ltc2471_groups);
> +
> +	return PTR_ERR_OR_ZERO(hwmon_dev);
> +}
> +
> +static const struct i2c_device_id ltc2471_i2c_id[] = {
> +	{ "ltc2471", ltc2471 },
> +	{ "ltc2473", ltc2473 },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, ltc2471_i2c_id);
> +
> +static struct i2c_driver ltc2471_i2c_driver = {
> +	.driver = {
> +		.name = "ltc2471",
> +	},
> +	.probe    = ltc2471_i2c_probe,
> +	.id_table = ltc2471_i2c_id,
> +};
> +
> +module_i2c_driver(ltc2471_i2c_driver);
> +
> +MODULE_DESCRIPTION("LTC2471/LTC2473 Sensor Driver");
> +MODULE_AUTHOR("Topic Embedded Products");
> +MODULE_LICENSE("GPL v2");
> 

^ permalink raw reply	[flat|nested] 9+ messages in thread
    • end of thread, other threads:[~2017-07-01  9:58 UTC | newest]

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     [not found] <1498733135-4729-1-git-send-email-mike.looijmans@topic.nl>
     [not found] ` <1498738434-18252-1-git-send-email-mike.looijmans@topic.nl>
2017-06-29 12:30   ` [PATCH v2] hwmon: Add LTC2471/LTC2473 driver Lars-Peter Clausen
2017-06-29 13:22     ` Mike Looijmans
2017-06-29 13:41       ` Guenter Roeck
2017-06-29 13:40     ` Guenter Roeck
2017-06-29 14:11       ` Mike Looijmans
2017-06-29 15:08         ` Guenter Roeck
2017-06-29 15:30         ` Lars-Peter Clausen
2017-06-29 13:34 ` [PATCH] " Guenter Roeck
2017-07-01  9:58   ` Jonathan Cameron

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