diff options
Diffstat (limited to 'drivers/hwmon/nsa320-hwmon.c')
| -rw-r--r-- | drivers/hwmon/nsa320-hwmon.c | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/drivers/hwmon/nsa320-hwmon.c b/drivers/hwmon/nsa320-hwmon.c new file mode 100644 index 000000000..0517a2657 --- /dev/null +++ b/drivers/hwmon/nsa320-hwmon.c @@ -0,0 +1,215 @@ +/* + * 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 show_label(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 show_temp(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 show_fan(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(temp1_label, S_IRUGO, show_label, NULL, NSA320_TEMP); +static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL); +static SENSOR_DEVICE_ATTR(fan1_label, S_IRUGO, show_label, NULL, NSA320_FAN); +static DEVICE_ATTR(fan1_input, S_IRUGO, show_fan, NULL); + +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"); |