/*
* drivers/hwmon/nsa320-hwmon.c
*
* ZyXEL NSA320 Media Servers
* hardware monitoring
*
* Copyright (C) 2016 Adam Baker <linux@baker-net.org.uk>
* based on a board file driver
* Copyright (C) 2012 Peter Schildmann <linux@schildmann.info>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License v2 as published by the
* Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*/
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
/* Tests for error return values rely upon this value being < 0x80 */
#define MAGIC_NUMBER 0x55
/*
* The Zyxel hwmon MCU is a Holtek HT46R065 that is factory programmed
* to perform temperature and fan speed monitoring. It is read by taking
* the active pin low. The 32 bit output word is then clocked onto the
* data line. The MSB of the data word is a magic nuber to indicate it
* has been read correctly, the next byte is the fan speed (in hundreds
* of RPM) and the last two bytes are the temperature (in tenths of a
* degree)
*/
struct nsa320_hwmon {
struct mutex update_lock; /* lock GPIO operations */
unsigned long last_updated; /* jiffies */
unsigned long mcu_data;
struct gpio_desc *act;
struct gpio_desc *clk;
struct gpio_desc *data;
};
enum nsa320_inputs {
NSA320_TEMP = 0,
NSA320_FAN = 1,
};
static const char * const nsa320_input_names[] = {
[NSA320_TEMP] = "System Temperature",
[NSA320_FAN] = "Chassis Fan",
};
/*
* Although this protocol looks similar to SPI the long delay
* between the active (aka chip select) signal and the shorter
* delay between clock pulses are needed for reliable operation.
* The delays provided are taken from the manufacturer kernel,
* testing suggest they probably incorporate a reasonable safety
* margin. (The single device tested became unreliable if the
* delay was reduced to 1/10th of this value.)
*/
static s32 nsa320_hwmon_update(struct device *dev)
{
u32 mcu_data;
u32 mask;
struct nsa320_hwmon *hwmon = dev_get_drvdata(dev);
mutex_lock(&hwmon->update_lock);
mcu_data = hwmon->mcu_data;
if (time_after(jiffies, hwmon->last_updated + HZ) || mcu_data == 0) {
gpiod_set_value(hwmon->act, 1);
msleep(100);
mcu_data = 0;
for (mask = BIT(31); mask; mask >>= 1) {
gpiod_set_value(hwmon->clk, 0);
usleep_range(100, 200);
gpiod_set_value(hwmon->clk, 1);
usleep_range(100, 200);
if (gpiod_get_value(hwmon->data))
mcu_data |= mask;
}
gpiod_set_value(hwmon->act, 0);
dev_dbg(dev, "Read raw MCU data %08x\n", mcu_data);
if ((mcu_data >> 24) != MAGIC_NUMBER) {
dev_dbg(dev, "Read invalid MCU data %08x\n", mcu_data);
mcu_data = -EIO;
} else {
hwmon->mcu_data = mcu_data;
hwmon->last_updated = jiffies;
}
}
mutex_unlock(&hwmon->update_lock);
return mcu_data;
}
static ssize_t label_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
int channel = to_sensor_dev_attr(attr)->index;
return sprintf(buf, "%s\n", nsa320_input_names[channel]);
}
static ssize_t temp1_input_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
s32 mcu_data = nsa320_hwmon_update(dev);
if (mcu_data < 0)
return mcu_data;
return sprintf(buf, "%d\n", (mcu_data & 0xffff) * 100);
}
static ssize_t fan1_input_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
s32 mcu_data = nsa320_hwmon_update(dev);
if (mcu_data < 0)
return mcu_data;
return sprintf(buf, "%d\n", ((mcu_data & 0xff0000) >> 16) * 100);
}
static SENSOR_DEVICE_ATTR_RO(temp1_label, label, NSA320_TEMP);
static DEVICE_ATTR_RO(temp1_input);
static SENSOR_DEVICE_ATTR_RO(fan1_label, label, NSA320_FAN);
static DEVICE_ATTR_RO(fan1_input);
static struct attribute *nsa320_attrs[] = {
&sensor_dev_attr_temp1_label.dev_attr.attr,
&dev_attr_temp1_input.attr,
&sensor_dev_attr_fan1_label.dev_attr.attr,
&dev_attr_fan1_input.attr,
NULL
};
ATTRIBUTE_GROUPS(nsa320);
static const struct of_device_id of_nsa320_hwmon_match[] = {
{ .compatible = "zyxel,nsa320-mcu", },
{ },
};
static int nsa320_hwmon_probe(struct platform_device *pdev)
{
struct nsa320_hwmon *hwmon;
struct device *classdev;
hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
if (!hwmon)
return -ENOMEM;
/* Look up the GPIO pins to use */
hwmon->act = devm_gpiod_get(&pdev->dev, "act", GPIOD_OUT_LOW);
if (IS_ERR(hwmon->act))
return PTR_ERR(hwmon->act);
hwmon->clk = devm_gpiod_get(&pdev->dev, "clk", GPIOD_OUT_HIGH);
if (IS_ERR(hwmon->clk))
return PTR_ERR(hwmon->clk);
hwmon->data = devm_gpiod_get(&pdev->dev, "data", GPIOD_IN);
if (IS_ERR(hwmon->data))
return PTR_ERR(hwmon->data);
mutex_init(&hwmon->update_lock);
classdev = devm_hwmon_device_register_with_groups(&pdev->dev,
"nsa320", hwmon, nsa320_groups);
return PTR_ERR_OR_ZERO(classdev);
}
/* All allocations use devres so remove() is not needed. */
static struct platform_driver nsa320_hwmon_driver = {
.probe = nsa320_hwmon_probe,
.driver = {
.name = "nsa320-hwmon",
.of_match_table = of_match_ptr(of_nsa320_hwmon_match),
},
};
module_platform_driver(nsa320_hwmon_driver);
MODULE_DEVICE_TABLE(of, of_nsa320_hwmon_match);
MODULE_AUTHOR("Peter Schildmann <linux@schildmann.info>");
MODULE_AUTHOR("Adam Baker <linux@baker-net.org.uk>");
MODULE_DESCRIPTION("NSA320 Hardware Monitoring");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:nsa320-hwmon");
