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Release 4.10 drivers/hwmon/nsa320-hwmon.c

Directory: drivers/hwmon
/*
 * 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; }

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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]); }

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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); }

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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); }

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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); }

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/* 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");

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Directory: drivers/hwmon
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