Re: [PATCH] hwmon: Add LTC2471/LTC2473 driver
From: Guenter Roeck
Date: Thu Jun 29 2017 - 09:38:08 EST
On 06/29/2017 04:18 AM, Frans Klaver wrote:
On Thu, Jun 29, 2017 at 12:45 PM, Mike Looijmans
<mike.looijmans@xxxxxxxx> 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@xxxxxxxx>
---
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@xxxxxxxx>
+ *
+ * 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;
+};
I haven't checked if there are similar drivers, but how about
ltc247x_data? It's a bit odd to tie all naming in this driver to one
chip and then support another one as well.
No, we don't do that, since it implies ltc247[0-9] which could be completely different chips.
Guenter
+
+/* 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);
Octal permissions are preferred over S_IRUGO and such.
+
+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);
sizeof(*data)
+ 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");
--
1.9.1
Frans
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