Message-ID: <20090621060216.GA25786@liondog.tnic>
Date:	Sun, 21 Jun 2009 08:02:16 +0200
From:	Borislav Petkov <petkovbb@...glemail.com>
To:	Peter Feuerer <peter@...e.net>
Cc:	Andreas Mohr <andi@...as.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Acer Aspire One fan control, simplified and scrubbed

Hi,

On Sat, Jun 20, 2009 at 08:38:46PM +0200, Peter Feuerer wrote:
> You removed the feature of controlling the fan from userspace, while the
> driver is running in kernelmode=off!
> ( echo 0 > /sys/class/thermal/thermal_zone0/cdev0/cur_state calls also the
> acerhdf_set_cur_state function )

I still don't really see the need for this since the module is doing
pretty good job already. Besides, its not like there is really a need
for userspace daemon doing heavy calculations and based on those
controlls the fan - simply turning it on and off based on the current
temp readings is what is needed and the thermal layer does that just
fine already :).

> --
> 
> Acerhdf is a driver for Acer Aspire One netbooks. It allows
> to access the temperature sensor and to control the fan.
> 
> Peter:
> 
>  - fixed bios table terminator Version string ( 0 to "" )
>  - added acerhdf_enable_kernelmode
>  - modified acerhdf_revert_to_bios_mode to disable polling
>  - modified acerhdf_get_temp to omit the pr_notice (temperature
>    should not be printed out in verbose mode, when called from
>    acerhdf_set_cur_state)

see below for some minor nitpicking.

> 
> Signed-off-by: Peter Feuerer <peter@...e.net>
> Signed-off-by: Andreas Mohr <andi@...as.de>
> Signed-off-by: Borislav Petkov <petkovbb@...il.com>
> ---
> diff --git a/MAINTAINERS b/MAINTAINERS
> index dc226e7..aea0ec2 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -230,6 +230,13 @@ L:	linux-acenic@...site.dk
>  S:	Maintained
>  F:	drivers/net/acenic*
>  
> +ACER ASPIRE ONE TEMPERATURE AND FAN DRIVER
> +P: Peter Feuerer
> +M: peter@...e.net
> +W: http://piie.net/?section=acerhdf
> +S: Maintained
> +F: drivers/platform/x86/acerhdf.c
> +
>  ACER WMI LAPTOP EXTRAS
>  P:	Carlos Corbacho
>  M:	carlos@...angeworlds.co.uk
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index c682ac5..5613483 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -34,6 +34,23 @@ config ACER_WMI
>  	  If you have an ACPI-WMI compatible Acer/ Wistron laptop, say Y or M
>  	  here.
>  
> +config ACERHDF
> +	tristate "Acer Aspire One temperature and fan driver"
> +	depends on THERMAL && THERMAL_HWMON && ACPI
> +	---help---
> +	  This is a driver for Acer Aspire One netbooks. It allows to access
> +	  the temperature sensor and to control the fan.
> +
> +	  After loading this driver the BIOS is still in control of the fan.
> +	  To let the kernel handle the fan, do:
> +	  echo -n enabled > /sys/class/thermal/thermal_zone0/mode
> +
> +	  For more information about this driver see
> +	  <http://piie.net/files/acerhdf_README.txt>
> +
> +	  If you have an Acer Aspire One netbook, say Y or M
> +	  here.
> +
>  config ASUS_LAPTOP
>  	tristate "Asus Laptop Extras (EXPERIMENTAL)"
>  	depends on ACPI
> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> index e40c7bd..641b8bf 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -9,6 +9,7 @@ obj-$(CONFIG_COMPAL_LAPTOP)	+= compal-laptop.o
>  obj-$(CONFIG_DELL_LAPTOP)	+= dell-laptop.o
>  obj-$(CONFIG_DELL_WMI)		+= dell-wmi.o
>  obj-$(CONFIG_ACER_WMI)		+= acer-wmi.o
> +obj-$(CONFIG_ACERHDF)		+= acerhdf.o
>  obj-$(CONFIG_HP_WMI)		+= hp-wmi.o
>  obj-$(CONFIG_TC1100_WMI)	+= tc1100-wmi.o
>  obj-$(CONFIG_SONY_LAPTOP)	+= sony-laptop.o
> diff --git a/drivers/platform/x86/acerhdf.c b/drivers/platform/x86/acerhdf.c
> new file mode 100644
> index 0000000..1e631cc
> --- /dev/null
> +++ b/drivers/platform/x86/acerhdf.c
> @@ -0,0 +1,602 @@
> +/*
> + * acerhdf - A driver which monitors the temperature
> + *           of the aspire one netbook, turns on/off the fan
> + *           as soon as the upper/lower threshold is reached.
> + *
> + * (C) 2009 - Peter Feuerer     peter (a) piie.net
> + *                              http://piie.net
> + *     2009 Borislav Petkov <petkovbb@...il.com>
> + *
> + * Inspired by and many thanks to:
> + *  o acerfand   - Rachel Greenham
> + *  o acer_ec.pl - Michael Kurz     michi.kurz (at) googlemail.com
> + *               - Petr Tomasek     tomasek (#) etf,cuni,cz
> + *               - Carlos Corbacho  cathectic (at) gmail.com
> + *  o lkml       - Matthew Garrett
> + *               - Borislav Petkov
> + *               - Andreas Mohr
> + *
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License as published by
> + *  the Free Software Foundation; either version 2 of the License, or
> + *  (at your option) any later version.
> + *
> + *  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.
> + *
> + *  You should have received a copy of the GNU General Public License
> + *  along with this program; if not, write to the Free Software
> + *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
> + */
> +
> +#define pr_fmt(fmt) "acerhdf: " fmt
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/fs.h>
> +#include <linux/dmi.h>
> +#include <acpi/acpi_drivers.h>
> +#include <linux/sched.h>
> +#include <linux/thermal.h>
> +#include <linux/platform_device.h>
> +
> +/*
> + * The driver is started with "kernel mode off" by default. That means, the BIOS
> + * is still in control of the fan. In this mode the driver allows to read the
> + * temperature of the cpu and a userspace tool may take over control of the fan.
> + * If the driver is switched to "kernel mode" (e.g. via module parameter) the
> + * driver is in full control of the fan. If you want the module to be started in
> + * kernel mode by default, define the following:
> + */
> +#undef START_IN_KERNEL_MODE
> +
> +#define DRV_VER "0.5.12"
> +
> +/*
> + * According to the Atom N270 datasheet,
> + * (http://download.intel.com/design/processor/datashts/320032.pdf) the
> + * CPU's optimal operating limits denoted in junction temperature as
> + * measured by the on-die thermal monitor are within 0 <= Tj <= 90. So,
> + * assume 89°C is critical temperature.
> + */
> +#define ACERHDF_TEMP_CRIT 89
> +#define ACERHDF_FAN_OFF 0
> +#define ACERHDF_FAN_AUTO 1
> +
> +/*
> + * No matter what value the user puts into the fanon variable, turn on the fan
> + * at 80 degree Celsius to prevent hardware damage
> + */
> +#define ACERHDF_MAX_FANON 80
> +
> +/*
> + * Maximum interval between two temperature checks is 15 seconds, as the die
> + * can get hot really fast under heavy load (plus we shouldn't forget about
> + * possible impact of _external_ aggressive sources such as heaters, sun etc.)
> + */
> +#define ACERHDF_MAX_INTERVAL 15
> +
> +#ifdef START_IN_KERNEL_MODE
> +static int kernelmode = 1;
> +#else
> +static int kernelmode;
> +#endif
> +
> +static unsigned int interval = 10;
> +static unsigned int fanon = 63;
> +static unsigned int fanoff = 58;
> +static unsigned int verbose;
> +static unsigned int fanstate = ACERHDF_FAN_AUTO;
> +static char force_bios[16];
> +static unsigned int prev_interval;
> +struct thermal_zone_device *thz_dev;
> +struct thermal_cooling_device *cl_dev;
> +struct platform_device *acerhdf_dev;
> +
> +module_param(kernelmode, uint, 0);
> +MODULE_PARM_DESC(kernelmode, "Kernel mode fan control on / off");
> +module_param(interval, uint, 0600);
> +MODULE_PARM_DESC(interval, "Polling interval of temperature check");
> +module_param(fanon, uint, 0600);
> +MODULE_PARM_DESC(fanon, "Turn the fan on above this temperature");
> +module_param(fanoff, uint, 0600);
> +MODULE_PARM_DESC(fanoff, "Turn the fan off below this temperature");
> +module_param(verbose, uint, 0600);
> +MODULE_PARM_DESC(verbose, "Enable verbose dmesg output");
> +module_param_string(force_bios, force_bios, 16, 0);
> +MODULE_PARM_DESC(force_bios, "Force BIOS version and omit BIOS check");
> +
> +/* BIOS settings */
> +struct bios_settings_t {
> +	const char *vendor;
> +	const char *version;
> +	unsigned char fanreg;
> +	unsigned char tempreg;
> +	unsigned char fancmd[2]; /* fan off and auto commands */
> +};
> +
> +/* Register addresses and values for different BIOS versions */
> +static const struct bios_settings_t bios_tbl[] = {
> +	{"Acer", "v0.3109", 0x55, 0x58, {0x1f, 0x00} },
> +	{"Acer", "v0.3114", 0x55, 0x58, {0x1f, 0x00} },
> +	{"Acer", "v0.3301", 0x55, 0x58, {0xaf, 0x00} },
> +	{"Acer", "v0.3304", 0x55, 0x58, {0xaf, 0x00} },
> +	{"Acer", "v0.3305", 0x55, 0x58, {0xaf, 0x00} },
> +	{"Acer", "v0.3308", 0x55, 0x58, {0x21, 0x00} },
> +	{"Acer", "v0.3309", 0x55, 0x58, {0x21, 0x00} },
> +	{"Acer", "v0.3310", 0x55, 0x58, {0x21, 0x00} },
> +	{"Gateway", "v0.3103", 0x55, 0x58, {0x21, 0x00} },
> +	{"Packard Bell", "v0.3105", 0x55, 0x58, {0x21, 0x00} },
> +	{"", "", 0, 0, {0, 0} }
> +};
> +
> +static const struct bios_settings_t *bios_cfg __read_mostly;
> +
> +
> +static int acerhdf_get_temp(int *temp, int report)

No, please don't add function arguments which have no functional
relevance besides echoing some verbose messages. This makes the code
unnecessarily bloated. Simply move the

	if (verbose)
		pr_notice("temp %d\n", read_temp);

call into the .get_temp callback, acerhdf_get_ec_temp.

> +{
> +	u8 read_temp;
> +
> +	if (ec_read(bios_cfg->tempreg, &read_temp))
> +		return -EINVAL;
> +
> +	if (verbose && report)
> +		pr_notice("temp %d\n", read_temp);
> +	*temp = read_temp;
> +
> +	return 0;
> +}
> +
> +static int acerhdf_get_fanstate(int *state)
> +{
> +	u8 fan;
> +	bool tmp;
> +
> +	if (ec_read(bios_cfg->fanreg, &fan))
> +		return -EINVAL;
> +
> +	tmp = (fan == bios_cfg->fancmd[ACERHDF_FAN_OFF]);
> +	*state = tmp ? ACERHDF_FAN_OFF : ACERHDF_FAN_AUTO;
> +
> +	return 0;
> +}
> +
> +static void acerhdf_change_fanstate(int state)
> +{
> +	unsigned char cmd;
> +
> +	if (verbose)
> +		pr_notice("fan %s\n", (state == ACERHDF_FAN_OFF) ?
> +				"OFF" : "ON");
> +
> +	if ((state != ACERHDF_FAN_OFF) && (state != ACERHDF_FAN_AUTO)) {
> +		pr_err("invalid fan state %d requested, setting to auto!\n",
> +			state);
> +		state = ACERHDF_FAN_AUTO;
> +	}
> +
> +	cmd = bios_cfg->fancmd[state];
> +	fanstate = state;
> +
> +	ec_write(bios_cfg->fanreg, cmd);
> +}
> +
> +static void acerhdf_check_param(struct thermal_zone_device *thermal)
> +{
> +	if (fanon > ACERHDF_MAX_FANON) {
> +		pr_err("fanon temperature too high, set to %d\n",
> +				ACERHDF_MAX_FANON);
> +		fanon = ACERHDF_MAX_FANON;
> +	}
> +
> +	if (kernelmode && prev_interval != interval) {
> +		if (interval > ACERHDF_MAX_INTERVAL) {
> +			pr_err("interval too high, set to %d\n",
> +				ACERHDF_MAX_INTERVAL);
> +			interval = ACERHDF_MAX_INTERVAL;
> +		}
> +		if (verbose)
> +			pr_notice("interval changed to: %d\n",
> +					interval);
> +		thermal->polling_delay = interval*1000;
> +		prev_interval = interval;
> +	}
> +}
> +
> +/*
> + * This is the thermal zone callback which does the delayed polling of the fan
> + * state. We do check /sysfs-originating settings here in acerhdf_check_param()
> + * as late as the polling interval is since we can't do that in the respective
> + * accessors of the module parameters.
> + */
> +static int acerhdf_get_ec_temp(struct thermal_zone_device *thermal,
> +			       unsigned long *t)
> +{
> +	int temp, err = 0;
> +
> +	acerhdf_check_param(thermal);
> +
> +	err = acerhdf_get_temp(&temp, 1);
> +	if (err)
> +		return err;
> +
> +	*t = temp;
> +	return 0;
> +}
> +
> +static int acerhdf_bind(struct thermal_zone_device *thermal,
> +			struct thermal_cooling_device *cdev)
> +{
> +	/* if the cooling device is the one from acerhdf bind it */
> +	if (cdev != cl_dev)
> +		return 0;
> +
> +	if (thermal_zone_bind_cooling_device(thermal, 0, cdev)) {
> +		pr_err("error binding cooling dev\n");
> +		return -EINVAL;
> +	}
> +	return 0;
> +}
> +
> +static int acerhdf_unbind(struct thermal_zone_device *thermal,
> +			  struct thermal_cooling_device *cdev)
> +{
> +	if (cdev != cl_dev)
> +		return 0;
> +
> +	if (thermal_zone_unbind_cooling_device(thermal, 0, cdev)) {
> +		pr_err("error unbinding cooling dev\n");
> +		return -EINVAL;
> +	}
> +	return 0;
> +}
> +
> +static inline void acerhdf_revert_to_bios_mode(void)
> +{
> +	acerhdf_change_fanstate(ACERHDF_FAN_AUTO);
> +	kernelmode = 0;
> +	if (thz_dev)
> +		thz_dev->polling_delay = 0;
> +	pr_notice("kernel mode fan control OFF\n");
> +}
> +static inline void acerhdf_enable_kernelmode(void)
> +{
> +	kernelmode = 1;
> +
> +	thz_dev->polling_delay = interval*1000;
> +	thermal_zone_device_update(thz_dev);
> +	pr_notice("kernel mode fan control ON\n");
> +}
> +
> +static int acerhdf_get_mode(struct thermal_zone_device *thermal,
> +			    enum thermal_device_mode *mode)
> +{
> +	if (verbose)
> +		pr_notice("kernel mode fan control %d\n", kernelmode);
> +
> +	*mode = (kernelmode) ? THERMAL_DEVICE_ENABLED
> +			     : THERMAL_DEVICE_DISABLED;
> +
> +	return 0;
> +}
> +
> +/*
> + * set operation mode;
> + * enabled: the thermal layer of the kernel takes care about
> + *          the temperature and the fan.
> + * disabled: the BIOS takes control of the fan.
> + */
> +static int acerhdf_set_mode(struct thermal_zone_device *thermal,
> +			    enum thermal_device_mode mode)
> +{
> +	if (mode == THERMAL_DEVICE_DISABLED && kernelmode)
> +		acerhdf_revert_to_bios_mode();
> +	else if (mode == THERMAL_DEVICE_ENABLED && !kernelmode)
> +		acerhdf_enable_kernelmode();
> +
> +	return 0;
> +}
> +
> +static int acerhdf_get_trip_type(struct thermal_zone_device *thermal, int trip,
> +				 enum thermal_trip_type *type)
> +{
> +	if (trip == 0)
> +		*type = THERMAL_TRIP_ACTIVE;
> +
> +	return 0;
> +}
> +
> +static int acerhdf_get_trip_temp(struct thermal_zone_device *thermal, int trip,
> +				 unsigned long *temp)
> +{
> +	if (trip == 0)
> +		*temp = fanon;
> +
> +	return 0;
> +}
> +
> +static int acerhdf_get_crit_temp(struct thermal_zone_device *thermal,
> +				 unsigned long *temperature)
> +{
> +	*temperature = ACERHDF_TEMP_CRIT;
> +	return 0;
> +}
> +
> +/* bind callback functions to thermalzone */
> +struct thermal_zone_device_ops acerhdf_dev_ops = {
> +	.bind = acerhdf_bind,
> +	.unbind = acerhdf_unbind,
> +	.get_temp = acerhdf_get_ec_temp,
> +	.get_mode = acerhdf_get_mode,
> +	.set_mode = acerhdf_set_mode,
> +	.get_trip_type = acerhdf_get_trip_type,
> +	.get_trip_temp = acerhdf_get_trip_temp,
> +	.get_crit_temp = acerhdf_get_crit_temp,
> +};
> +
> +
> +/*
> + * cooling device callback functions
> + * get maximal fan cooling state
> + */
> +static int acerhdf_get_max_state(struct thermal_cooling_device *cdev,
> +				 unsigned long *state)
> +{
> +	*state = 1;
> +
> +	return 0;
> +}
> +
> +static int acerhdf_get_cur_state(struct thermal_cooling_device *cdev,
> +				 unsigned long *state)
> +{
> +	int err = 0, tmp;
> +
> +	err = acerhdf_get_fanstate(&tmp);
> +	if (err)
> +		return err;
> +
> +	*state = (tmp == ACERHDF_FAN_AUTO) ? 1 : 0;
> +	return 0;
> +}
> +
> +/* change current fan state - is overwritten when running in kernel mode */
> +static int acerhdf_set_cur_state(struct thermal_cooling_device *cdev,
> +				 unsigned long state)
> +{
> +	int cur_temp, cur_state, err = 0;
> +
> +	if (!kernelmode)
> +		return 0;
> +
> +	err = acerhdf_get_temp(&cur_temp, 0);
> +	if (err) {
> +		pr_err("error reading temperature, hand off control to BIOS\n");
> +		goto err_out;
> +	}
> +
> +	err = acerhdf_get_fanstate(&cur_state);
> +	if (err) {
> +		pr_err("error reading fan state, hand off control to BIOS\n");
> +		goto err_out;
> +	}
> +
> +	if (state == 0) {
> +		/* turn fan off only if below fanoff temperature */
> +		if ((cur_state == ACERHDF_FAN_AUTO) &&
> +		    (cur_temp < fanoff))
> +			acerhdf_change_fanstate(ACERHDF_FAN_OFF);
> +	} else {
> +		if (cur_state == ACERHDF_FAN_OFF)
> +			acerhdf_change_fanstate(ACERHDF_FAN_AUTO);
> +	}
> +	return 0;
> +
> +err_out:
> +	acerhdf_revert_to_bios_mode();
> +	return -EINVAL;
> +}
> +
> +/* bind fan callbacks to fan device */
> +struct thermal_cooling_device_ops acerhdf_cooling_ops = {
> +	.get_max_state = acerhdf_get_max_state,
> +	.get_cur_state = acerhdf_get_cur_state,
> +	.set_cur_state = acerhdf_set_cur_state,
> +};
> +
> +/* suspend / resume functionality */
> +static int acerhdf_suspend(struct platform_device *dev,	pm_message_t state)
							^^^^^^^^^
							runaway tab

> +{
> +	if (kernelmode)
> +		acerhdf_change_fanstate(ACERHDF_FAN_AUTO);
> +
> +	if (verbose)
> +		pr_notice("going suspend\n");
> +
> +	return 0;
> +}
> +
> +static int acerhdf_resume(struct platform_device *device)
> +{
> +	if (verbose)
> +		pr_notice("resuming\n");
> +
> +	return 0;
> +}
> +
> +static int __devinit acerhdf_probe(struct platform_device *device)
> +{
> +	return 0;
> +}
> +
> +static int acerhdf_remove(struct platform_device *device)
> +{
> +	return 0;
> +}
> +
> +struct platform_driver acerhdf_drv = {
> +	.driver = {
> +		.name = "acerhdf",
> +		.owner = THIS_MODULE,
> +	},
> +	.probe = acerhdf_probe,
> +	.remove = acerhdf_remove,
> +	.suspend = acerhdf_suspend,
> +	.resume = acerhdf_resume,
> +};
> +
> +
> +/* check hardware */
> +static int acerhdf_check_hardware(void)
> +{
> +	char const *vendor, *version, *product;
> +	int i;
> +
> +	/* get BIOS data */
> +	vendor  = dmi_get_system_info(DMI_SYS_VENDOR);
> +	version = dmi_get_system_info(DMI_BIOS_VERSION);
> +	product = dmi_get_system_info(DMI_PRODUCT_NAME);
> +
> +	pr_info("Acer Aspire One Fan driver, v.%s\n", DRV_VER);
> +
> +	if (!force_bios[0]) {
> +		if (strncmp(product, "AO", 2)) {
> +			pr_err("no Aspire One hardware found\n");
> +			return -EINVAL;
> +		}
> +	} else {
> +		pr_info("forcing BIOS version: %s\n", version);
> +		version = force_bios;
> +		kernelmode = 0;
> +	}
> +
> +	if (verbose)
> +		pr_info("BIOS info: %s %s, product: %s\n",
> +			vendor, version, product);
> +
> +	/* search BIOS version and vendor in BIOS settings table */
> +	for (i = 0; bios_tbl[i].version[0]; i++) {
> +		if (!strcmp(bios_tbl[i].vendor, vendor) &&
> +		    !strcmp(bios_tbl[i].version, version)) {
> +			bios_cfg = &bios_tbl[i];
> +			break;
> +		}
> +	}
> +
> +	if (!bios_cfg) {
> +		pr_err("unknown (unsupported) BIOS version %s/%s, "
> +			"please report, aborting!\n", vendor, version);
> +		return -EINVAL;
> +	}
> +
> +	/*
> +	 * if started with kernel mode off, prevent the kernel from switching
> +	 * off the fan
> +	 */
> +	if (!kernelmode) {
> +		pr_notice("Fan control off, to enable do:\n");
> +		pr_notice("echo -n \"enabled\" > "
> +			"/sys/class/thermal/thermal_zone0/mode\n");
> +	}
> +
> +	return 0;
> +}
> +
> +static int acerhdf_register_platform(void)
> +{
> +	int err = 0;
> +
> +	err = platform_driver_register(&acerhdf_drv);
> +	if (err)
> +		return err;
> +
> +	acerhdf_dev = platform_device_alloc("acerhdf", -1);
> +	platform_device_add(acerhdf_dev);
> +
> +	return 0;
> +}
> +
> +static void acerhdf_unregister_platform(void)
> +{
> +	if (!acerhdf_dev)
> +		return;
> +
> +	platform_device_del(acerhdf_dev);
> +	platform_driver_unregister(&acerhdf_drv);
> +}
> +
> +static int acerhdf_register_thermal(void)
> +{
> +	cl_dev = thermal_cooling_device_register("acerhdf-fan", NULL,
> +						 &acerhdf_cooling_ops);
> +
> +	if (IS_ERR(cl_dev))
> +		return -EINVAL;
> +
> +	thz_dev = thermal_zone_device_register("acerhdf", 1, NULL,
> +					      &acerhdf_dev_ops, 0, 0, 0,
> +					      (kernelmode) ? interval*1000 : 0);
> +	if (IS_ERR(thz_dev))
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static void acerhdf_unregister_thermal(void)
> +{
> +	if (cl_dev) {
> +		thermal_cooling_device_unregister(cl_dev);
> +		cl_dev = NULL;
> +	}
> +
> +	if (thz_dev) {
> +		thermal_zone_device_unregister(thz_dev);
> +		thz_dev = NULL;
> +	}
> +}
> +
> +/* kernel module init / exit functions */

no need for that comment

> +static int __init acerhdf_init(void)
> +{
> +	int err = 0;
> +
> +	err = acerhdf_check_hardware();
> +	if (err)
> +		goto out_err;
> +
> +	err = acerhdf_register_platform();
> +	if (err)
> +		goto err_unreg;
> +
> +	err = acerhdf_register_thermal();
> +	if (err)
> +		goto err_unreg;
> +
> +	return 0;
> +
> +err_unreg:
> +	acerhdf_unregister_thermal();
> +	acerhdf_unregister_platform();
> +
> +out_err:
> +	return -ENODEV;
> +}
> +
> +static void __exit acerhdf_exit(void)
> +{
> +	acerhdf_change_fanstate(ACERHDF_FAN_AUTO);
> +	acerhdf_unregister_thermal();
> +	acerhdf_unregister_platform();
> +}
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Peter Feuerer");
> +MODULE_DESCRIPTION("Aspire One temperature and fan driver");
> +MODULE_ALIAS("dmi:*:*Acer*:*:");
> +MODULE_ALIAS("dmi:*:*Gateway*:*:");
> +MODULE_ALIAS("dmi:*:*Packard Bell*:*:");
> +
> +module_init(acerhdf_init);
> +module_exit(acerhdf_exit);

-- 
Regards/Gruss,
    Boris.
--
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