Date:   Sat, 1 Apr 2017 12:59:18 -0700
From:   Eduardo Valentin <edubezval@...il.com>
To:     Steve Twiss <stwiss.opensource@...semi.com>
Cc:     LINUX-KERNEL <linux-kernel@...r.kernel.org>,
        LINUX-PM <linux-pm@...r.kernel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        DEVICETREE <devicetree@...r.kernel.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Guenter Roeck <linux@...ck-us.net>,
        LINUX-INPUT <linux-input@...r.kernel.org>,
        LINUX-WATCHDOG <linux-watchdog@...r.kernel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Lukasz Luba <lukasz.luba@....com>,
        Mark Brown <broonie@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Support Opensource <support.opensource@...semi.com>,
        Wim Van Sebroeck <wim@...ana.be>
Subject: Re: [PATCH V7 6/7] thermal: da9062/61: Thermal junction temperature
 monitoring driver

Hello,

On Tue, Mar 28, 2017 at 03:43:33PM +0100, Steve Twiss wrote:
> From: Steve Twiss <stwiss.opensource@...semi.com>
> 
> Add junction temperature monitoring supervisor device driver, compatible
> with the DA9062 and DA9061 PMICs. A MODULE_DEVICE_TABLE() macro is added.
> 
> If the PMIC's internal junction temperature rises above T_WARN (125 degC)
> an interrupt is issued. This T_WARN level is defined as the
> THERMAL_TRIP_HOT trip-wire inside the device driver.
> 
> The thermal triggering mechanism is interrupt based and happens when the
> temperature rises above a given threshold level. The component cannot
> return an exact temperature, it only has knowledge if the temperature is
> above or below a given threshold value. A status bit must be polled to
> detect when the temperature falls below that threshold level again. A
> kernel work queue is configured to repeatedly poll and detect when the
> temperature falls below this trip-wire, between 1 and 10 second intervals
> (defaulting at 3 seconds).
> 
> This scheme is provided as an example. It would be expected that any
> final implementation will also include a notify() function and any of these
> settings could be altered to match the application where appropriate.
> 
> When over-temperature is reached, the interrupt from the DA9061/2 will be
> repeatedly triggered. The IRQ is therefore disabled when the first
> over-temperature event happens and the status bit is polled using a
> work-queue until it becomes false.
> 
> This strategy is designed to allow the periodic transmission of uevents
> (HOT trip point) as the first level of temperature supervision method. It
> is intended for non-invasive temperature control, where the necessary
> measures for cooling the system down are left to the host software. Once
> the temperature falls again, the IRQ is re-enabled so a new critical
> over-temperature event can be detected.
> 
> Reviewed-by: Lukasz Luba <lukasz.luba@....com>
> Signed-off-by: Steve Twiss <stwiss.opensource@...semi.com>

I have had a look on the history of this driver on its previous
versions, and I do not think I have any other point to request on it.
Obviously, I still need to state that I do not like its oddness as it is
not really benefiting much of the thermal control implemented on the
thermal subsystem.

What is the plan for this series? Am I expected to get this driver
through thermal tree ? Or is this series going into a one shot?

If option 1 is the expected, would the driver need to get its
mfd parent merged first?
> 
> ---
> This patch applies against linux-next and v4.11-rc3
> 
> v6 -> v7
>  - NO CODE CHANGE
>  - Compile tested ARCH=x86_64
> 
> v5 -> v6
>  - Patch renamed from [PATCH V5 7/8] to [PATCH V6 6/7]
>  - Rebased from v4.9 to v4.11-rc3
>  - Modify Copyright to match Dialog latest legal statement
>  - Various checkpatch warnings (from --strict) have been fixed
>  - Added COMPILE_TEST to Kconfig
> 
> v4 -> v5
>  - Rebased from v4.8 to v4.9
>  - Updates from comments by Eduardo Valentin
>  - Replace vendor defined dlg,tjunc-temp-polling-period-ms with standard
>    thermal core polling-delay-passive as part of the device tree
>    initialisation
>  - Change to the commit message content and device driver source code to
>    include an explanation of the repeated uevent strategy for monitoring
>    over-temperature
>  - Rename warning threshold name from TEMP_WARN to T_WARN to match the
>    latest datasheet naming convention
>  - Added reviewed-by Lukasz Luba to commit message
> 
> v3 -> v4
>  - Patch renamed from [PATCH V3 8/9] to [PATCH V4 7/8]
>  - Reordering of cancel_delayed_work_sync() in remove function
>  - dev_warn() message for out-of-range polling period requests
>  - Explanatory comment for expected values defined for
>    DEFAULT_POLLING_MS_PERIOD, MAX_POLLING_MS_PERIOD and
>    MIN_POLLING_MS_PERIOD
> 
> v2 -> v3
>  - Patch renamed from [PATCH V2 09/10] to [PATCH V3 8/9]
>  - Addition of MODULE_DEVICE_TABLE macro to allow modinfo additions
> 
> v1 -> v2
>  - Patch renamed from [PATCH V1 05/10] to [PATCH V2 09/10] -- these
>    changes were made to fix checkpatch warnings caused by the patch
>    set dependency order
>  - List the header files in alphabetical order
>  - Remove "GPL v2" and replace with MODULE_LICENSE("GPL") to match the
>    copyright "GNU Public License v2 or later" option in the header
>    comment for this file. See the allowed identifiers in the file
>    include/linux/module.h +170
>  - Remove notify function "da9062_thermal_notify" function.
>  - MODULE_AUTHOR() macros removes Company Name and just gives Name in
>    accordance with include/linux/module.h +200
>  - Remove the compatible "dlg,da9061-thermal" option in the of_device_id
>    struct table. This patch now assumes the use of a DA9062 fallback
>    compatible string in the DTS when using the DA9061 thermal component
>    of the DA9061 device.
>  - Re-ordered some assignments earlier in the probe() for thermal->hw,
>    thermal->polling_period, thermal->mode, thermal->dev
>  - Added further information in the patch description to explain the use
>    of the device driver's built-in work-queue.
> 
> Regards,
> Steve Twiss, Dialog Semiconductor
> 
> 
>  drivers/thermal/Kconfig          |  10 ++
>  drivers/thermal/Makefile         |   1 +
>  drivers/thermal/da9062-thermal.c | 315 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 326 insertions(+)
>  create mode 100644 drivers/thermal/da9062-thermal.c
> 
> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> index 776b3439..a784b02 100644
> --- a/drivers/thermal/Kconfig
> +++ b/drivers/thermal/Kconfig
> @@ -303,6 +303,16 @@ config DB8500_CPUFREQ_COOLING
>  	  bound cpufreq cooling device turns active to set CPU frequency low to
>  	  cool down the CPU.
>  
> +config DA9062_THERMAL
> +	tristate "DA9062/DA9061 Dialog Semiconductor thermal driver"
> +	depends on MFD_DA9062 || COMPILE_TEST
> +	depends on OF
> +	help
> +	  Enable this for the Dialog Semiconductor thermal sensor driver.
> +	  This will report PMIC junction over-temperature for one thermal trip
> +	  zone.
> +	  Compatible with the DA9062 and DA9061 PMICs.
> +
>  config INTEL_POWERCLAMP
>  	tristate "Intel PowerClamp idle injection driver"
>  	depends on THERMAL
> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
> index 7adae20..297849e 100644
> --- a/drivers/thermal/Makefile
> +++ b/drivers/thermal/Makefile
> @@ -42,6 +42,7 @@ obj-$(CONFIG_IMX_THERMAL)	+= imx_thermal.o
>  obj-$(CONFIG_MAX77620_THERMAL)	+= max77620_thermal.o
>  obj-$(CONFIG_QORIQ_THERMAL)	+= qoriq_thermal.o
>  obj-$(CONFIG_DB8500_CPUFREQ_COOLING)	+= db8500_cpufreq_cooling.o
> +obj-$(CONFIG_DA9062_THERMAL)	+= da9062-thermal.o
>  obj-$(CONFIG_INTEL_POWERCLAMP)	+= intel_powerclamp.o
>  obj-$(CONFIG_X86_PKG_TEMP_THERMAL)	+= x86_pkg_temp_thermal.o
>  obj-$(CONFIG_INTEL_SOC_DTS_IOSF_CORE)	+= intel_soc_dts_iosf.o
> diff --git a/drivers/thermal/da9062-thermal.c b/drivers/thermal/da9062-thermal.c
> new file mode 100644
> index 0000000..dd8dd94
> --- /dev/null
> +++ b/drivers/thermal/da9062-thermal.c
> @@ -0,0 +1,315 @@
> +/*
> + * Thermal device driver for DA9062 and DA9061
> + * Copyright (C) 2017  Dialog Semiconductor
> + *
> + * 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.
> + */
> +
> +/* When over-temperature is reached, an interrupt from the device will be
> + * triggered. Following this event the interrupt will be disabled and
> + * periodic transmission of uevents (HOT trip point) should define the
> + * first level of temperature supervision. It is expected that any final
> + * implementation of the thermal driver will include a .notify() function
> + * to implement these uevents to userspace.
> + *
> + * These uevents are intended to indicate non-invasive temperature control
> + * of the system, where the necessary measures for cooling are the
> + * responsibility of the host software. Once the temperature falls again,
> + * the IRQ is re-enabled so the start of a new over-temperature event can
> + * be detected without constant software monitoring.
> + */
> +
> +#include <linux/errno.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/thermal.h>
> +#include <linux/workqueue.h>
> +
> +#include <linux/mfd/da9062/core.h>
> +#include <linux/mfd/da9062/registers.h>
> +
> +/* Minimum, maximum and default polling millisecond periods are provided
> + * here as an example. It is expected that any final implementation to also
> + * include a modification of these settings to match the required
> + * application.
> + */
> +#define DA9062_DEFAULT_POLLING_MS_PERIOD	3000
> +#define DA9062_MAX_POLLING_MS_PERIOD		10000
> +#define DA9062_MIN_POLLING_MS_PERIOD		1000
> +
> +#define DA9062_MILLI_CELSIUS(t)			((t) * 1000)
> +
> +struct da9062_thermal_config {
> +	const char *name;
> +};
> +
> +struct da9062_thermal {
> +	struct da9062 *hw;
> +	struct delayed_work work;
> +	struct thermal_zone_device *zone;
> +	enum thermal_device_mode mode;
> +	struct mutex lock; /* protection for da9062_thermal temperature */
> +	int temperature;
> +	int irq;
> +	const struct da9062_thermal_config *config;
> +	struct device *dev;
> +};
> +
> +static void da9062_thermal_poll_on(struct work_struct *work)
> +{
> +	struct da9062_thermal *thermal = container_of(work,
> +						struct da9062_thermal,
> +						work.work);
> +	unsigned long delay;
> +	unsigned int val;
> +	int ret;
> +
> +	/* clear E_TEMP */
> +	ret = regmap_write(thermal->hw->regmap,
> +			   DA9062AA_EVENT_B,
> +			   DA9062AA_E_TEMP_MASK);
> +	if (ret < 0) {
> +		dev_err(thermal->dev,
> +			"Cannot clear the TJUNC temperature status\n");
> +		goto err_enable_irq;
> +	}
> +
> +	/* Now read E_TEMP again: it is acting like a status bit.
> +	 * If over-temperature, then this status will be true.
> +	 * If not over-temperature, this status will be false.
> +	 */
> +	ret = regmap_read(thermal->hw->regmap,
> +			  DA9062AA_EVENT_B,
> +			  &val);
> +	if (ret < 0) {
> +		dev_err(thermal->dev,
> +			"Cannot check the TJUNC temperature status\n");
> +		goto err_enable_irq;
> +	}
> +
> +	if (val & DA9062AA_E_TEMP_MASK) {
> +		mutex_lock(&thermal->lock);
> +		thermal->temperature = DA9062_MILLI_CELSIUS(125);
> +		mutex_unlock(&thermal->lock);
> +		thermal_zone_device_update(thermal->zone,
> +					   THERMAL_EVENT_UNSPECIFIED);
> +
> +		delay = msecs_to_jiffies(thermal->zone->passive_delay);
> +		schedule_delayed_work(&thermal->work, delay);
> +		return;
> +	}
> +
> +	mutex_lock(&thermal->lock);
> +	thermal->temperature = DA9062_MILLI_CELSIUS(0);
> +	mutex_unlock(&thermal->lock);
> +	thermal_zone_device_update(thermal->zone,
> +				   THERMAL_EVENT_UNSPECIFIED);
> +
> +err_enable_irq:
> +	enable_irq(thermal->irq);
> +}
> +
> +static irqreturn_t da9062_thermal_irq_handler(int irq, void *data)
> +{
> +	struct da9062_thermal *thermal = data;
> +
> +	disable_irq_nosync(thermal->irq);
> +	schedule_delayed_work(&thermal->work, 0);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int da9062_thermal_get_mode(struct thermal_zone_device *z,
> +				   enum thermal_device_mode *mode)
> +{
> +	struct da9062_thermal *thermal = z->devdata;
> +	*mode = thermal->mode;
> +	return 0;
> +}
> +
> +static int da9062_thermal_get_trip_type(struct thermal_zone_device *z,
> +					int trip,
> +					enum thermal_trip_type *type)
> +{
> +	struct da9062_thermal *thermal = z->devdata;
> +
> +	switch (trip) {
> +	case 0:
> +		*type = THERMAL_TRIP_HOT;
> +		break;
> +	default:
> +		dev_err(thermal->dev,
> +			"Driver does not support more than 1 trip-wire\n");
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int da9062_thermal_get_trip_temp(struct thermal_zone_device *z,
> +					int trip,
> +					int *temp)
> +{
> +	struct da9062_thermal *thermal = z->devdata;
> +
> +	switch (trip) {
> +	case 0:
> +		*temp = DA9062_MILLI_CELSIUS(125);
> +		break;
> +	default:
> +		dev_err(thermal->dev,
> +			"Driver does not support more than 1 trip-wire\n");
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int da9062_thermal_get_temp(struct thermal_zone_device *z,
> +				   int *temp)
> +{
> +	struct da9062_thermal *thermal = z->devdata;
> +
> +	mutex_lock(&thermal->lock);
> +	*temp = thermal->temperature;
> +	mutex_unlock(&thermal->lock);
> +
> +	return 0;
> +}
> +
> +static struct thermal_zone_device_ops da9062_thermal_ops = {
> +	.get_temp	= da9062_thermal_get_temp,
> +	.get_mode	= da9062_thermal_get_mode,
> +	.get_trip_type	= da9062_thermal_get_trip_type,
> +	.get_trip_temp	= da9062_thermal_get_trip_temp,
> +};
> +
> +static const struct da9062_thermal_config da9062_config = {
> +	.name = "da9062-thermal",
> +};
> +
> +static const struct of_device_id da9062_compatible_reg_id_table[] = {
> +	{ .compatible = "dlg,da9062-thermal", .data = &da9062_config },
> +	{ },
> +};
> +
> +MODULE_DEVICE_TABLE(of, da9062_compatible_reg_id_table);
> +
> +static int da9062_thermal_probe(struct platform_device *pdev)
> +{
> +	struct da9062 *chip = dev_get_drvdata(pdev->dev.parent);
> +	struct da9062_thermal *thermal;
> +	unsigned int pp_tmp = DA9062_DEFAULT_POLLING_MS_PERIOD;
> +	const struct of_device_id *match;
> +	int ret = 0;
> +
> +	match = of_match_node(da9062_compatible_reg_id_table,
> +			      pdev->dev.of_node);
> +	if (!match)
> +		return -ENXIO;
> +
> +	if (pdev->dev.of_node) {
> +		if (!of_property_read_u32(pdev->dev.of_node,
> +					  "polling-delay-passive",
> +					  &pp_tmp)) {
> +			if (pp_tmp < DA9062_MIN_POLLING_MS_PERIOD ||
> +			    pp_tmp > DA9062_MAX_POLLING_MS_PERIOD) {
> +				dev_warn(&pdev->dev,
> +					 "Out-of-range polling period %d ms\n",
> +					 pp_tmp);
> +				pp_tmp = DA9062_DEFAULT_POLLING_MS_PERIOD;
> +			}
> +		}
> +	}
> +
> +	thermal = devm_kzalloc(&pdev->dev, sizeof(struct da9062_thermal),
> +			       GFP_KERNEL);
> +	if (!thermal) {
> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +
> +	thermal->config = match->data;
> +	thermal->hw = chip;
> +	thermal->mode = THERMAL_DEVICE_ENABLED;
> +	thermal->dev = &pdev->dev;
> +
> +	INIT_DELAYED_WORK(&thermal->work, da9062_thermal_poll_on);
> +	mutex_init(&thermal->lock);
> +
> +	thermal->zone = thermal_zone_device_register(thermal->config->name,
> +					1, 0, thermal,
> +					&da9062_thermal_ops, NULL, pp_tmp,
> +					0);
> +	if (IS_ERR(thermal->zone)) {
> +		dev_err(&pdev->dev, "Cannot register thermal zone device\n");
> +		ret = PTR_ERR(thermal->zone);
> +		goto err;
> +	}
> +
> +	dev_dbg(&pdev->dev,
> +		"TJUNC temperature polling period set at %d ms\n",
> +		thermal->zone->passive_delay);
> +
> +	ret = platform_get_irq_byname(pdev, "THERMAL");
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "Failed to get platform IRQ.\n");
> +		goto err_zone;
> +	}
> +	thermal->irq = ret;
> +
> +	ret = request_threaded_irq(thermal->irq, NULL,
> +				   da9062_thermal_irq_handler,
> +				   IRQF_TRIGGER_LOW | IRQF_ONESHOT,
> +				   "THERMAL", thermal);
> +	if (ret) {
> +		dev_err(&pdev->dev,
> +			"Failed to request thermal device IRQ.\n");
> +		goto err_zone;
> +	}
> +
> +	platform_set_drvdata(pdev, thermal);
> +	return 0;
> +
> +err_zone:
> +	thermal_zone_device_unregister(thermal->zone);
> +err:
> +	return ret;
> +}
> +
> +static int da9062_thermal_remove(struct platform_device *pdev)
> +{
> +	struct	da9062_thermal *thermal = platform_get_drvdata(pdev);
> +
> +	free_irq(thermal->irq, thermal);
> +	cancel_delayed_work_sync(&thermal->work);
> +	thermal_zone_device_unregister(thermal->zone);
> +	return 0;
> +}
> +
> +static struct platform_driver da9062_thermal_driver = {
> +	.probe	= da9062_thermal_probe,
> +	.remove	= da9062_thermal_remove,
> +	.driver	= {
> +		.name	= "da9062-thermal",
> +		.of_match_table = da9062_compatible_reg_id_table,
> +	},
> +};
> +
> +module_platform_driver(da9062_thermal_driver);
> +
> +MODULE_AUTHOR("Steve Twiss");
> +MODULE_DESCRIPTION("Thermal TJUNC device driver for Dialog DA9062 and DA9061");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:da9062-thermal");
> -- 
> end-of-patch for PATCH V7
> 

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