hwmon: (abx500) Decomission abx500 driver

This deletes the ABx500 hwmon driver, the only supported
variant being the AB8500.

This driver has been replaced by generic frameworks. By
inspecting the abx500 sysfs files we see that it contains
things such as temp1_max, temp1_max_alarm, temp1_max_hyst,
temp1_max_hyst_alarm, temp1_min, temp1_min_alarm.

It becomes obvious that the abx500.c is a reimplementation
of thermal zones. This is not very strange as the generic
thermal zones were not invented when this driver was merged
so people were rolling their own.

The ab8500.c driver contains conversion tables for handling
a thermistor on ADC channels AUX1 and AUX2.

I managed to replace the functionality of the driver with:

- Activation of the ntc_thermistor.c driver,
  CONFIG_SENSORS_NTC_THERMISTOR
- Activation of thermal zones, CONFIG_THERMAL
- In the device tree, connecting the NTC driver to the
  processed IIO channels from the AB8500 GPADC ADC forming
  two instances of NTC sensors.
- Connecting the two NTC sensors to a "chassis" thermal zone
  in the device tree and setting that to hit the CPU frequency
  at 50 degrees celsius and do a critical shutdown at 70
  degrees celsius, deploying a policy using the sensors.

After talking to the original authors we concluded that the
driver was never properly parameterized in production so
what we now have in the device tree is already puts the
thermistors to better use than what the hwmon driver did.

The two remaining channels for two battery temperatures is
already handled in the charging algorithms but can be
optionally extended to thermal zones as well if we want
these to trigger critical shutdown for the platform.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20201221125521.768082-1-linus.walleij@linaro.org
[groeck: Removed documentation and fixed up Makefile, Kconfig]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/ab8500.rst

-Kernel driver ab8500
-====================
-
-Supported chips:
-
-  * ST-Ericsson AB8500
-
-    Prefix: 'ab8500'
-
-    Addresses scanned: -
-
-    Datasheet: http://www.stericsson.com/developers/documentation.jsp
-
-Authors:
-	- Martin Persson <martin.persson@stericsson.com>
-	- Hongbo Zhang <hongbo.zhang@linaro.org>
-
-Description
------------
-
-See also Documentation/hwmon/abx500.rst. This is the ST-Ericsson AB8500 specific
-driver.
-
-Currently only the AB8500 internal sensor and one external sensor for battery
-temperature are monitored. Other GPADC channels can also be monitored if needed
-in future.

Documentation/hwmon/abx500.rst

-Kernel driver abx500
-====================
-
-Supported chips:
-
-  * ST-Ericsson ABx500 series
-
-    Prefix: 'abx500'
-
-    Addresses scanned: -
-
-    Datasheet: http://www.stericsson.com/developers/documentation.jsp
-
-Authors:
-	Martin Persson <martin.persson@stericsson.com>
-	Hongbo Zhang <hongbo.zhang@linaro.org>
-
-Description
------------
-
-Every ST-Ericsson Ux500 SOC consists of both ABx500 and DBx500 physically,
-this is kernel hwmon driver for ABx500.
-
-There are some GPADCs inside ABx500 which are designed for connecting to
-thermal sensors, and there is also a thermal sensor inside ABx500 too, which
-raises interrupt when critical temperature reached.
-
-This abx500 is a common layer which can monitor all of the sensors, every
-specific abx500 chip has its special configurations in its own file, e.g. some
-sensors can be configured invisible if they are not available on that chip, and
-the corresponding gpadc_addr should be set to 0, thus this sensor won't be
-polled.

Documentation/hwmon/index.rst

@@ -18,10 +18,8 @@ Hardware Monitoring Kernel Drivers
 .. toctree::
    :maxdepth: 1
 
-   ab8500
    abituguru
    abituguru3
-   abx500
    acpi_power_meter
    ad7314
    adc128d818

drivers/hwmon/Kconfig

@@ -38,19 +38,6 @@ config HWMON_DEBUG_CHIP
 
 comment "Native drivers"
 
-config SENSORS_AB8500
-	tristate "AB8500 thermal monitoring"
-	depends on AB8500_GPADC && AB8500_BM && (IIO = y)
-	default n
-	help
-	  If you say yes here you get support for the thermal sensor part
-	  of the AB8500 chip. The driver includes thermal management for
-	  AB8500 die and two GPADC channels. The GPADC channel are preferably
-	  used to access sensors outside the AB8500 chip.
-
-	  This driver can also be built as a module. If so, the module
-	  will be called abx500-temp.
-
 config SENSORS_ABITUGURU
 	tristate "Abit uGuru (rev 1 & 2)"
 	depends on X86 && DMI

drivers/hwmon/Makefile

@@ -21,7 +21,6 @@ obj-$(CONFIG_SENSORS_W83795)	+= w83795.o
 obj-$(CONFIG_SENSORS_W83781D)	+= w83781d.o
 obj-$(CONFIG_SENSORS_W83791D)	+= w83791d.o
 
-obj-$(CONFIG_SENSORS_AB8500)	+= abx500.o ab8500.o
 obj-$(CONFIG_SENSORS_ABITUGURU)	+= abituguru.o
 obj-$(CONFIG_SENSORS_ABITUGURU3)+= abituguru3.o
 obj-$(CONFIG_SENSORS_AD7314)	+= ad7314.o

drivers/hwmon/ab8500.c

-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * Copyright (C) ST-Ericsson 2010 - 2013
- * Author: Martin Persson <martin.persson@stericsson.com>
- *         Hongbo Zhang <hongbo.zhang@linaro.org>
- *
- * When the AB8500 thermal warning temperature is reached (threshold cannot
- * be changed by SW), an interrupt is set, and if no further action is taken
- * within a certain time frame, kernel_power_off will be called.
- *
- * When AB8500 thermal shutdown temperature is reached a hardware shutdown of
- * the AB8500 will occur.
- */
-
-#include <linux/err.h>
-#include <linux/hwmon.h>
-#include <linux/hwmon-sysfs.h>
-#include <linux/mfd/abx500.h>
-#include <linux/mfd/abx500/ab8500-bm.h>
-#include <linux/module.h>
-#include <linux/platform_device.h>
-#include <linux/power/ab8500.h>
-#include <linux/reboot.h>
-#include <linux/slab.h>
-#include <linux/sysfs.h>
-#include <linux/iio/consumer.h>
-#include "abx500.h"
-
-#define DEFAULT_POWER_OFF_DELAY	(HZ * 10)
-#define THERMAL_VCC		1800
-#define PULL_UP_RESISTOR	47000
-
-#define AB8500_SENSOR_AUX1		0
-#define AB8500_SENSOR_AUX2		1
-#define AB8500_SENSOR_BTEMP_BALL	2
-#define AB8500_SENSOR_BAT_CTRL		3
-#define NUM_MONITORED_SENSORS		4
-
-struct ab8500_gpadc_cfg {
-	const struct abx500_res_to_temp *temp_tbl;
-	int tbl_sz;
-	int vcc;
-	int r_up;
-};
-
-struct ab8500_temp {
-	struct iio_channel *aux1;
-	struct iio_channel *aux2;
-	struct ab8500_btemp *btemp;
-	struct delayed_work power_off_work;
-	struct ab8500_gpadc_cfg cfg;
-	struct abx500_temp *abx500_data;
-};
-
-/*
- * The hardware connection is like this:
- * VCC----[ R_up ]-----[ NTC ]----GND
- * where R_up is pull-up resistance, and GPADC measures voltage on NTC.
- * and res_to_temp table is strictly sorted by falling resistance values.
- */
-static int ab8500_voltage_to_temp(struct ab8500_gpadc_cfg *cfg,
-		int v_ntc, int *temp)
-{
-	int r_ntc, i = 0, tbl_sz = cfg->tbl_sz;
-	const struct abx500_res_to_temp *tbl = cfg->temp_tbl;
-
-	if (cfg->vcc < 0 || v_ntc >= cfg->vcc)
-		return -EINVAL;
-
-	r_ntc = v_ntc * cfg->r_up / (cfg->vcc - v_ntc);
-	if (r_ntc > tbl[0].resist || r_ntc < tbl[tbl_sz - 1].resist)
-		return -EINVAL;
-
-	while (!(r_ntc <= tbl[i].resist && r_ntc > tbl[i + 1].resist) &&
-			i < tbl_sz - 2)
-		i++;
-
-	/* return milli-Celsius */
-	*temp = tbl[i].temp * 1000 + ((tbl[i + 1].temp - tbl[i].temp) * 1000 *
-		(r_ntc - tbl[i].resist)) / (tbl[i + 1].resist - tbl[i].resist);
-
-	return 0;
-}
-
-static int ab8500_read_sensor(struct abx500_temp *data, u8 sensor, int *temp)
-{
-	int voltage, ret;
-	struct ab8500_temp *ab8500_data = data->plat_data;
-
-	if (sensor == AB8500_SENSOR_BTEMP_BALL) {
-		*temp = ab8500_btemp_get_temp(ab8500_data->btemp);
-	} else if (sensor == AB8500_SENSOR_BAT_CTRL) {
-		*temp = ab8500_btemp_get_batctrl_temp(ab8500_data->btemp);
-	} else if (sensor == AB8500_SENSOR_AUX1) {
-		ret = iio_read_channel_processed(ab8500_data->aux1, &voltage);
-		if (ret < 0)
-			return ret;
-		ret = ab8500_voltage_to_temp(&ab8500_data->cfg, voltage, temp);
-		if (ret < 0)
-			return ret;
-	} else if (sensor == AB8500_SENSOR_AUX2) {
-		ret = iio_read_channel_processed(ab8500_data->aux2, &voltage);
-		if (ret < 0)
-			return ret;
-		ret = ab8500_voltage_to_temp(&ab8500_data->cfg, voltage, temp);
-		if (ret < 0)
-			return ret;
-	}
-
-	return 0;
-}
-
-static void ab8500_thermal_power_off(struct work_struct *work)
-{
-	struct ab8500_temp *ab8500_data = container_of(work,
-				struct ab8500_temp, power_off_work.work);
-	struct abx500_temp *abx500_data = ab8500_data->abx500_data;
-
-	dev_warn(&abx500_data->pdev->dev, "Power off due to critical temp\n");
-
-	kernel_power_off();
-}
-
-static ssize_t ab8500_show_name(struct device *dev,
-		struct device_attribute *devattr, char *buf)
-{
-	return sprintf(buf, "ab8500\n");
-}
-
-static ssize_t ab8500_show_label(struct device *dev,
-		struct device_attribute *devattr, char *buf)
-{
-	char *label;
-	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
-	int index = attr->index;
-
-	switch (index) {
-	case 1:
-		label = "ext_adc1";
-		break;
-	case 2:
-		label = "ext_adc2";
-		break;
-	case 3:
-		label = "bat_temp";
-		break;
-	case 4:
-		label = "bat_ctrl";
-		break;
-	default:
-		return -EINVAL;
-	}
-
-	return sprintf(buf, "%s\n", label);
-}
-
-static int ab8500_temp_irq_handler(int irq, struct abx500_temp *data)
-{
-	struct ab8500_temp *ab8500_data = data->plat_data;
-
-	dev_warn(&data->pdev->dev, "Power off in %d s\n",
-		 DEFAULT_POWER_OFF_DELAY / HZ);
-
-	schedule_delayed_work(&ab8500_data->power_off_work,
-		DEFAULT_POWER_OFF_DELAY);
-	return 0;
-}
-
-int abx500_hwmon_init(struct abx500_temp *data)
-{
-	struct ab8500_temp *ab8500_data;
-
-	ab8500_data = devm_kzalloc(&data->pdev->dev, sizeof(*ab8500_data),
-		GFP_KERNEL);
-	if (!ab8500_data)
-		return -ENOMEM;
-
-	ab8500_data->btemp = ab8500_btemp_get();
-	if (IS_ERR(ab8500_data->btemp))
-		return PTR_ERR(ab8500_data->btemp);
-
-	INIT_DELAYED_WORK(&ab8500_data->power_off_work,
-			  ab8500_thermal_power_off);
-
-	ab8500_data->cfg.vcc = THERMAL_VCC;
-	ab8500_data->cfg.r_up = PULL_UP_RESISTOR;
-	ab8500_data->cfg.temp_tbl = ab8500_temp_tbl_a_thermistor;
-	ab8500_data->cfg.tbl_sz = ab8500_temp_tbl_a_size;
-
-	data->plat_data = ab8500_data;
-	ab8500_data->aux1 = devm_iio_channel_get(&data->pdev->dev, "aux1");
-	if (IS_ERR(ab8500_data->aux1)) {
-		if (PTR_ERR(ab8500_data->aux1) == -ENODEV)
-			return -EPROBE_DEFER;
-		dev_err(&data->pdev->dev, "failed to get AUX1 ADC channel\n");
-		return PTR_ERR(ab8500_data->aux1);
-	}
-	ab8500_data->aux2 = devm_iio_channel_get(&data->pdev->dev, "aux2");
-	if (IS_ERR(ab8500_data->aux2)) {
-		if (PTR_ERR(ab8500_data->aux2) == -ENODEV)
-			return -EPROBE_DEFER;
-		dev_err(&data->pdev->dev, "failed to get AUX2 ADC channel\n");
-		return PTR_ERR(ab8500_data->aux2);
-	}
-
-	data->gpadc_addr[0] = AB8500_SENSOR_AUX1;
-	data->gpadc_addr[1] = AB8500_SENSOR_AUX2;
-	data->gpadc_addr[2] = AB8500_SENSOR_BTEMP_BALL;
-	data->gpadc_addr[3] = AB8500_SENSOR_BAT_CTRL;
-	data->monitored_sensors = NUM_MONITORED_SENSORS;
-
-	data->ops.read_sensor = ab8500_read_sensor;
-	data->ops.irq_handler = ab8500_temp_irq_handler;
-	data->ops.show_name = ab8500_show_name;
-	data->ops.show_label = ab8500_show_label;
-	data->ops.is_visible = NULL;
-
-	return 0;
-}
-EXPORT_SYMBOL(abx500_hwmon_init);
-
-MODULE_AUTHOR("Hongbo Zhang <hongbo.zhang@linaro.org>");
-MODULE_DESCRIPTION("AB8500 temperature driver");
-MODULE_LICENSE("GPL");

drivers/hwmon/abx500.h

-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Copyright (C) ST-Ericsson 2010 - 2013
- * Author: Martin Persson <martin.persson@stericsson.com>
- *         Hongbo Zhang <hongbo.zhang@linaro.com>
- */
-
-#ifndef _ABX500_H
-#define _ABX500_H
-
-#define NUM_SENSORS 5
-
-struct abx500_temp;
-
-/*
- * struct abx500_temp_ops - abx500 chip specific ops
- * @read_sensor: reads gpadc output
- * @irq_handler: irq handler
- * @show_name: hwmon device name
- * @show_label: hwmon attribute label
- * @is_visible: is attribute visible
- */
-struct abx500_temp_ops {
-	int (*read_sensor)(struct abx500_temp *, u8, int *);
-	int (*irq_handler)(int, struct abx500_temp *);
-	ssize_t (*show_name)(struct device *,
-			struct device_attribute *, char *);
-	ssize_t (*show_label) (struct device *,
-			struct device_attribute *, char *);
-	int (*is_visible)(struct attribute *, int);
-};
-
-/*
- * struct abx500_temp - representation of temp mon device
- * @pdev: platform device
- * @hwmon_dev: hwmon device
- * @ops: abx500 chip specific ops
- * @gpadc_addr: gpadc channel address
- * @min: sensor temperature min value
- * @max: sensor temperature max value
- * @max_hyst: sensor temperature hysteresis value for max limit
- * @min_alarm: sensor temperature min alarm
- * @max_alarm: sensor temperature max alarm
- * @work: delayed work scheduled to monitor temperature periodically
- * @work_active: True if work is active
- * @lock: mutex
- * @monitored_sensors: number of monitored sensors
- * @plat_data: private usage, usually points to platform specific data
- */
-struct abx500_temp {
-	struct platform_device *pdev;
-	struct device *hwmon_dev;
-	struct abx500_temp_ops ops;
-	u8 gpadc_addr[NUM_SENSORS];
-	unsigned long min[NUM_SENSORS];
-	unsigned long max[NUM_SENSORS];
-	unsigned long max_hyst[NUM_SENSORS];
-	bool min_alarm[NUM_SENSORS];
-	bool max_alarm[NUM_SENSORS];
-	struct delayed_work work;
-	bool work_active;
-	struct mutex lock;
-	int monitored_sensors;
-	void *plat_data;
-};
-
-int abx500_hwmon_init(struct abx500_temp *data);
-
-#endif /* _ABX500_H */