hwmon: LTC4261 Hardware monitoring driver
This driver adds support for Linear Technology LTC4261 I2C Negative Voltage Hot Swap Controller. Reviewed-by: Ira W. Snyder <iws@ovro.caltech.edu> Reviewed-by: Tom Grennan <tom.grennan@ericsson.com> Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>hifive-unleashed-5.1
Guenter Roeck
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Kernel driver ltc4261
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=====================
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Supported chips:
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* Linear Technology LTC4261
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Prefix: 'ltc4261'
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Addresses scanned: -
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Datasheet:
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http://cds.linear.com/docs/Datasheet/42612fb.pdf
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Author: Guenter Roeck <guenter.roeck@ericsson.com>
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Description
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-----------
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The LTC4261/LTC4261-2 negative voltage Hot Swap controllers allow a board
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to be safely inserted and removed from a live backplane.
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Usage Notes
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-----------
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This driver does not probe for LTC4261 devices, since there is no register
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which can be safely used to identify the chip. You will have to instantiate
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the devices explicitly.
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Example: the following will load the driver for an LTC4261 at address 0x10
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on I2C bus #1:
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$ modprobe ltc4261
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$ echo ltc4261 0x10 > /sys/bus/i2c/devices/i2c-1/new_device
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Sysfs entries
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-------------
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Voltage readings provided by this driver are reported as obtained from the ADC
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registers. If a set of voltage divider resistors is installed, calculate the
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real voltage by multiplying the reported value with (R1+R2)/R2, where R1 is the
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value of the divider resistor against the measured voltage and R2 is the value
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of the divider resistor against Ground.
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Current reading provided by this driver is reported as obtained from the ADC
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Current Sense register. The reported value assumes that a 1 mOhm sense resistor
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is installed. If a different sense resistor is installed, calculate the real
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current by dividing the reported value by the sense resistor value in mOhm.
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The chip has two voltage sensors, but only one set of voltage alarm status bits.
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In many many designs, those alarms are associated with the ADIN2 sensor, due to
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the proximity of the ADIN2 pin to the OV pin. ADIN2 is, however, not available
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on all chip variants. To ensure that the alarm condition is reported to the user,
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report it with both voltage sensors.
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in1_input ADIN2 voltage (mV)
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in1_min_alarm ADIN/ADIN2 Undervoltage alarm
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in1_max_alarm ADIN/ADIN2 Overvoltage alarm
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in2_input ADIN voltage (mV)
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in2_min_alarm ADIN/ADIN2 Undervoltage alarm
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in2_max_alarm ADIN/ADIN2 Overvoltage alarm
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curr1_input SENSE current (mA)
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curr1_alarm SENSE overcurrent alarm
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@ -3765,6 +3765,13 @@ L: linux-scsi@vger.kernel.org
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S: Maintained
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F: drivers/scsi/sym53c8xx_2/
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LTC4261 HARDWARE MONITOR DRIVER
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M: Guenter Roeck <linux@roeck-us.net>
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L: lm-sensors@lm-sensors.org
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S: Maintained
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F: Documentation/hwmon/ltc4261
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F: drivers/hwmon/ltc4261.c
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LTP (Linux Test Project)
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M: Rishikesh K Rajak <risrajak@linux.vnet.ibm.com>
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M: Garrett Cooper <yanegomi@gmail.com>
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@ -654,6 +654,17 @@ config SENSORS_LTC4245
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This driver can also be built as a module. If so, the module will
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be called ltc4245.
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config SENSORS_LTC4261
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tristate "Linear Technology LTC4261"
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depends on I2C && EXPERIMENTAL
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default n
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help
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If you say yes here you get support for Linear Technology LTC4261
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Negative Voltage Hot Swap Controller I2C interface.
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This driver can also be built as a module. If so, the module will
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be called ltc4261.
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config SENSORS_LM95241
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tristate "National Semiconductor LM95241 sensor chip"
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depends on I2C
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@ -79,6 +79,7 @@ obj-$(CONFIG_SENSORS_LM93) += lm93.o
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obj-$(CONFIG_SENSORS_LM95241) += lm95241.o
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obj-$(CONFIG_SENSORS_LTC4215) += ltc4215.o
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obj-$(CONFIG_SENSORS_LTC4245) += ltc4245.o
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obj-$(CONFIG_SENSORS_LTC4261) += ltc4261.o
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obj-$(CONFIG_SENSORS_MAX1111) += max1111.o
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obj-$(CONFIG_SENSORS_MAX1619) += max1619.o
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obj-$(CONFIG_SENSORS_MAX6650) += max6650.o
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@ -0,0 +1,315 @@
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/*
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* Driver for Linear Technology LTC4261 I2C Negative Voltage Hot Swap Controller
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*
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* Copyright (C) 2010 Ericsson AB.
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*
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* Derived from:
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*
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* Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller
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* Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu>
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*
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* Datasheet: http://cds.linear.com/docs/Datasheet/42612fb.pdf
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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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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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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/init.h>
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#include <linux/err.h>
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#include <linux/slab.h>
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#include <linux/i2c.h>
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#include <linux/hwmon.h>
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#include <linux/hwmon-sysfs.h>
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/* chip registers */
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#define LTC4261_STATUS 0x00 /* readonly */
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#define LTC4261_FAULT 0x01
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#define LTC4261_ALERT 0x02
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#define LTC4261_CONTROL 0x03
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#define LTC4261_SENSE_H 0x04
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#define LTC4261_SENSE_L 0x05
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#define LTC4261_ADIN2_H 0x06
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#define LTC4261_ADIN2_L 0x07
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#define LTC4261_ADIN_H 0x08
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#define LTC4261_ADIN_L 0x09
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/*
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* Fault register bits
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*/
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#define FAULT_OV (1<<0)
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#define FAULT_UV (1<<1)
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#define FAULT_OC (1<<2)
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struct ltc4261_data {
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struct device *hwmon_dev;
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struct mutex update_lock;
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bool valid;
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unsigned long last_updated; /* in jiffies */
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/* Registers */
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u8 regs[10];
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};
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static struct ltc4261_data *ltc4261_update_device(struct device *dev)
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{
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struct i2c_client *client = to_i2c_client(dev);
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struct ltc4261_data *data = i2c_get_clientdata(client);
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struct ltc4261_data *ret = data;
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mutex_lock(&data->update_lock);
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if (time_after(jiffies, data->last_updated + HZ / 4) || !data->valid) {
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int i;
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/* Read registers -- 0x00 to 0x09 */
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for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
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int val;
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val = i2c_smbus_read_byte_data(client, i);
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if (unlikely(val < 0)) {
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dev_dbg(dev,
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"Failed to read ADC value: error %d",
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val);
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ret = ERR_PTR(val);
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goto abort;
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}
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data->regs[i] = val;
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}
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data->last_updated = jiffies;
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data->valid = 1;
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}
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abort:
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mutex_unlock(&data->update_lock);
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return ret;
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}
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/* Return the voltage from the given register in mV or mA */
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static int ltc4261_get_value(struct ltc4261_data *data, u8 reg)
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{
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u32 val;
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val = (data->regs[reg] << 2) + (data->regs[reg + 1] >> 6);
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switch (reg) {
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case LTC4261_ADIN_H:
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case LTC4261_ADIN2_H:
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/* 2.5mV resolution. Convert to mV. */
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val = val * 25 / 10;
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break;
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case LTC4261_SENSE_H:
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/*
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* 62.5uV resolution. Convert to current as measured with
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* an 1 mOhm sense resistor, in mA. If a different sense
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* resistor is installed, calculate the actual current by
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* dividing the reported current by the sense resistor value
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* in mOhm.
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*/
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val = val * 625 / 10;
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break;
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default:
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/* If we get here, the developer messed up */
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WARN_ON_ONCE(1);
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val = 0;
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break;
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}
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return val;
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}
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static ssize_t ltc4261_show_value(struct device *dev,
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struct device_attribute *da, char *buf)
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{
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struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
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struct ltc4261_data *data = ltc4261_update_device(dev);
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int value;
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if (IS_ERR(data))
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return PTR_ERR(data);
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value = ltc4261_get_value(data, attr->index);
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return snprintf(buf, PAGE_SIZE, "%d\n", value);
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}
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static ssize_t ltc4261_show_bool(struct device *dev,
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struct device_attribute *da, char *buf)
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{
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struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
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struct i2c_client *client = to_i2c_client(dev);
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struct ltc4261_data *data = ltc4261_update_device(dev);
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u8 fault;
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if (IS_ERR(data))
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return PTR_ERR(data);
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fault = data->regs[LTC4261_FAULT] & attr->index;
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if (fault) /* Clear reported faults in chip register */
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i2c_smbus_write_byte_data(client, LTC4261_FAULT, ~fault);
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return snprintf(buf, PAGE_SIZE, "%d\n", fault ? 1 : 0);
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}
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/*
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* These macros are used below in constructing device attribute objects
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* for use with sysfs_create_group() to make a sysfs device file
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* for each register.
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*/
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#define LTC4261_VALUE(name, ltc4261_cmd_idx) \
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static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
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ltc4261_show_value, NULL, ltc4261_cmd_idx)
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#define LTC4261_BOOL(name, mask) \
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static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
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ltc4261_show_bool, NULL, (mask))
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/*
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* Input voltages.
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*/
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LTC4261_VALUE(in1_input, LTC4261_ADIN_H);
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LTC4261_VALUE(in2_input, LTC4261_ADIN2_H);
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/*
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* Voltage alarms. The chip has only one set of voltage alarm status bits,
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* triggered by input voltage alarms. In many designs, those alarms are
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* associated with the ADIN2 sensor, due to the proximity of the ADIN2 pin
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* to the OV pin. ADIN2 is, however, not available on all chip variants.
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* To ensure that the alarm condition is reported to the user, report it
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* with both voltage sensors.
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*/
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LTC4261_BOOL(in1_min_alarm, FAULT_UV);
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LTC4261_BOOL(in1_max_alarm, FAULT_OV);
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LTC4261_BOOL(in2_min_alarm, FAULT_UV);
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LTC4261_BOOL(in2_max_alarm, FAULT_OV);
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/* Currents (via sense resistor) */
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LTC4261_VALUE(curr1_input, LTC4261_SENSE_H);
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/* Overcurrent alarm */
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LTC4261_BOOL(curr1_max_alarm, FAULT_OC);
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static struct attribute *ltc4261_attributes[] = {
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&sensor_dev_attr_in1_input.dev_attr.attr,
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&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
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&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
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&sensor_dev_attr_in2_input.dev_attr.attr,
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&sensor_dev_attr_in2_min_alarm.dev_attr.attr,
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&sensor_dev_attr_in2_max_alarm.dev_attr.attr,
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&sensor_dev_attr_curr1_input.dev_attr.attr,
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&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
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NULL,
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};
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static const struct attribute_group ltc4261_group = {
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.attrs = ltc4261_attributes,
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};
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static int ltc4261_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct i2c_adapter *adapter = client->adapter;
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struct ltc4261_data *data;
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int ret;
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if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
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return -ENODEV;
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if (i2c_smbus_read_byte_data(client, LTC4261_STATUS) < 0) {
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dev_err(&client->dev, "Failed to read register %d:%02x:%02x\n",
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adapter->id, client->addr, LTC4261_STATUS);
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return -ENODEV;
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}
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data = kzalloc(sizeof(*data), GFP_KERNEL);
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if (!data) {
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ret = -ENOMEM;
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goto out_kzalloc;
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}
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i2c_set_clientdata(client, data);
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mutex_init(&data->update_lock);
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/* Clear faults */
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i2c_smbus_write_byte_data(client, LTC4261_FAULT, 0x00);
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/* Register sysfs hooks */
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ret = sysfs_create_group(&client->dev.kobj, <c4261_group);
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if (ret)
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goto out_sysfs_create_group;
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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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ret = PTR_ERR(data->hwmon_dev);
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goto out_hwmon_device_register;
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}
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return 0;
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out_hwmon_device_register:
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sysfs_remove_group(&client->dev.kobj, <c4261_group);
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out_sysfs_create_group:
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kfree(data);
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out_kzalloc:
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return ret;
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}
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static int ltc4261_remove(struct i2c_client *client)
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{
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struct ltc4261_data *data = i2c_get_clientdata(client);
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hwmon_device_unregister(data->hwmon_dev);
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sysfs_remove_group(&client->dev.kobj, <c4261_group);
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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 ltc4261_id[] = {
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{"ltc4261", 0},
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{}
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};
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MODULE_DEVICE_TABLE(i2c, ltc4261_id);
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/* This is the driver that will be inserted */
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static struct i2c_driver ltc4261_driver = {
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.driver = {
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.name = "ltc4261",
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},
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.probe = ltc4261_probe,
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.remove = ltc4261_remove,
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.id_table = ltc4261_id,
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};
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static int __init ltc4261_init(void)
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{
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return i2c_add_driver(<c4261_driver);
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}
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static void __exit ltc4261_exit(void)
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{
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i2c_del_driver(<c4261_driver);
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}
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MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>");
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MODULE_DESCRIPTION("LTC4261 driver");
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MODULE_LICENSE("GPL");
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module_init(ltc4261_init);
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module_exit(ltc4261_exit);
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