hwmon: Add MCP3021 ADC driver
Add I2C driver for MCP3021 that is an ADC chip from Microchip. The MCP3021 is a successive approximation A/D converter (ADC) with 10-bit resolution. The driver export the value of Vin to sysfs, the voltage unit is mV. Through the sysfs interface, lm-sensors tool can also display Vin voltage. Signed-off-by: Mingkai Hu <Mingkai.hu@freescale.com> Signed-off-by: Xie Xiaobo <X.Xie@freescale.com> Signed-off-by: Jean Delvare <khali@linux-fr.org>hifive-unleashed-5.1
Xie Xiaobo
Jean Delvare
parent
0c2732152a
commit
5510e62a66
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@ -0,0 +1,22 @@
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Kernel driver MCP3021
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======================
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Supported chips:
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* Microchip Technology MCP3021
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Prefix: 'mcp3021'
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Datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/21805a.pdf
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Author: Mingkai Hu
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Description
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-----------
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This driver implements support for the Microchip Technology MCP3021 chip.
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The Microchip Technology Inc. MCP3021 is a successive approximation A/D
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converter (ADC) with 10-bit resolution.
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This device provides one single-ended input with very low power consumption.
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Communication to the MCP3021 is performed using a 2-wire I2C compatible
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interface. Standard (100 kHz) and Fast (400 kHz) I2C modes are available.
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The default I2C device address is 0x4d (contact the Microchip factory for
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additional address options).
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@ -813,6 +813,16 @@ config SENSORS_MAX6650
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This driver can also be built as a module. If so, the module
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will be called max6650.
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config SENSORS_MCP3021
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tristate "Microchip MCP3021"
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depends on I2C && EXPERIMENTAL
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help
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If you say yes here you get support for the MCP3021 chip
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that is a A/D converter (ADC) with 10-bit resolution.
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This driver can also be built as a module. If so, the module
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will be called mcp3021.
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config SENSORS_NTC_THERMISTOR
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tristate "NTC thermistor support"
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depends on EXPERIMENTAL
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@ -95,6 +95,7 @@ obj-$(CONFIG_SENSORS_MAX6639) += max6639.o
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obj-$(CONFIG_SENSORS_MAX6642) += max6642.o
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obj-$(CONFIG_SENSORS_MAX6650) += max6650.o
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obj-$(CONFIG_SENSORS_MC13783_ADC)+= mc13783-adc.o
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obj-$(CONFIG_SENSORS_MCP3021) += mcp3021.o
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obj-$(CONFIG_SENSORS_NTC_THERMISTOR) += ntc_thermistor.o
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obj-$(CONFIG_SENSORS_PC87360) += pc87360.o
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obj-$(CONFIG_SENSORS_PC87427) += pc87427.o
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@ -0,0 +1,171 @@
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/*
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* mcp3021.c - driver for the Microchip MCP3021 chip
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*
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* Copyright (C) 2008-2009, 2012 Freescale Semiconductor, Inc.
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* Author: Mingkai Hu <Mingkai.hu@freescale.com>
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*
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* This driver export the value of analog input voltage to sysfs, the
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* voltage unit is mV. Through the sysfs interface, lm-sensors tool
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* can also display the input voltage.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/hwmon.h>
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#include <linux/slab.h>
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#include <linux/i2c.h>
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#include <linux/err.h>
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#include <linux/device.h>
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/* Vdd info */
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#define MCP3021_VDD_MAX 5500
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#define MCP3021_VDD_MIN 2700
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#define MCP3021_VDD_REF 3300
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/* output format */
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#define MCP3021_SAR_SHIFT 2
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#define MCP3021_SAR_MASK 0x3ff
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#define MCP3021_OUTPUT_RES 10 /* 10-bit resolution */
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#define MCP3021_OUTPUT_SCALE 4
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/*
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* Client data (each client gets its own)
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*/
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struct mcp3021_data {
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struct device *hwmon_dev;
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u32 vdd; /* device power supply */
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};
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static int mcp3021_read16(struct i2c_client *client)
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{
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int ret;
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u16 reg;
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__be16 buf;
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ret = i2c_master_recv(client, (char *)&buf, 2);
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if (ret < 0)
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return ret;
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if (ret != 2)
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return -EIO;
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/* The output code of the MCP3021 is transmitted with MSB first. */
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reg = be16_to_cpu(buf);
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/*
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* The ten-bit output code is composed of the lower 4-bit of the
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* first byte and the upper 6-bit of the second byte.
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*/
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reg = (reg >> MCP3021_SAR_SHIFT) & MCP3021_SAR_MASK;
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return reg;
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}
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static inline u16 volts_from_reg(u16 vdd, u16 val)
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{
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if (val == 0)
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return 0;
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val = val * MCP3021_OUTPUT_SCALE - MCP3021_OUTPUT_SCALE / 2;
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return val * DIV_ROUND_CLOSEST(vdd,
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(1 << MCP3021_OUTPUT_RES) * MCP3021_OUTPUT_SCALE);
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}
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static ssize_t show_in_input(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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struct i2c_client *client = to_i2c_client(dev);
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struct mcp3021_data *data = i2c_get_clientdata(client);
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int reg, in_input;
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reg = mcp3021_read16(client);
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if (reg < 0)
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return reg;
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in_input = volts_from_reg(data->vdd, reg);
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return sprintf(buf, "%d\n", in_input);
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}
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static DEVICE_ATTR(in0_input, S_IRUGO, show_in_input, NULL);
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static int mcp3021_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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int err;
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struct mcp3021_data *data = NULL;
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
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return -ENODEV;
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data = kzalloc(sizeof(struct mcp3021_data), GFP_KERNEL);
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if (!data)
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return -ENOMEM;
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i2c_set_clientdata(client, data);
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if (client->dev.platform_data) {
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data->vdd = *(u32 *)client->dev.platform_data;
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if (data->vdd > MCP3021_VDD_MAX ||
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data->vdd < MCP3021_VDD_MIN) {
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err = -EINVAL;
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goto exit_free;
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}
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} else
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data->vdd = MCP3021_VDD_REF;
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err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr);
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if (err)
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goto exit_free;
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data->hwmon_dev = hwmon_device_register(&client->dev);
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if (IS_ERR(data->hwmon_dev)) {
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err = PTR_ERR(data->hwmon_dev);
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goto exit_remove;
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}
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return 0;
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exit_remove:
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sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
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exit_free:
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kfree(data);
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return err;
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}
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static int mcp3021_remove(struct i2c_client *client)
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{
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struct mcp3021_data *data = i2c_get_clientdata(client);
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hwmon_device_unregister(data->hwmon_dev);
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sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
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kfree(data);
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return 0;
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}
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static const struct i2c_device_id mcp3021_id[] = {
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{ "mcp3021", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, mcp3021_id);
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static struct i2c_driver mcp3021_driver = {
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.driver = {
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.name = "mcp3021",
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},
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.probe = mcp3021_probe,
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.remove = mcp3021_remove,
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.id_table = mcp3021_id,
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};
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module_i2c_driver(mcp3021_driver);
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MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
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MODULE_DESCRIPTION("Microchip MCP3021 driver");
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MODULE_LICENSE("GPL");
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