Message-ID: <f2e82119-e0ee-108c-ca90-6fb6cb24eb77@collabora.com>
Date:   Fri, 21 Apr 2017 18:53:58 +0200
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     Sebastian Reichel <sre@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH 1/2] power: Add support for the Toby Churchill SBS battery
 monitor driver.

Hi,

On 15/03/17 22:52, Sebastian Reichel wrote:
> Hi,
> 
> On Thu, Feb 23, 2017 at 06:38:11PM +0100, Enric Balletbo i Serra wrote:
>> Some of the Toby Churchill devices come with a smart battery and one
>> AVR XMEGA Microcontroller monitor its state. This patch adds the driver
>> for this battery monitor.
> 
> Sorry for the delay. I'm mostly fine with the driver. You can find a
> few notes below.
> 
>> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
>> ---
>>  drivers/power/supply/Kconfig             |  10 +
>>  drivers/power/supply/Makefile            |   2 +
>>  drivers/power/supply/xmega16d4_battery.c | 353 +++++++++++++++++++++++++++++++
>>  3 files changed, 365 insertions(+)
>>  create mode 100644 drivers/power/supply/xmega16d4_battery.c
>>
>> diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
>> index 76806a0..f95f8d5 100644
>> --- a/drivers/power/supply/Kconfig
>> +++ b/drivers/power/supply/Kconfig
>> @@ -511,4 +511,14 @@ config AXP20X_POWER
>>  	  This driver provides support for the power supply features of
>>  	  AXP20x PMIC.
>>  
>> +config BATTERY_XMEGA16D4
>> +	tristate "XMEGA16D4 Battery Gauge Driver"
>> +	depends on SPI
>> +	help
>> +	  Say Y here to include support for XMEGA16D4 Battery Gauge. The
>> +	  driver reports the charge count, and measures the voltage and
>> +	  the current.
>> +
>> +	  This adds support for XMEGA16D4 battery.
>> +
>>  endif # POWER_SUPPLY
>> diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
>> index 36c599d..abae887 100644
>> --- a/drivers/power/supply/Makefile
>> +++ b/drivers/power/supply/Makefile
>> @@ -72,3 +72,5 @@ obj-$(CONFIG_CHARGER_TPS65090)	+= tps65090-charger.o
>>  obj-$(CONFIG_CHARGER_TPS65217)	+= tps65217_charger.o
>>  obj-$(CONFIG_AXP288_FUEL_GAUGE) += axp288_fuel_gauge.o
>>  obj-$(CONFIG_AXP288_CHARGER)	+= axp288_charger.o
>> +obj-$(CONFIG_BATTERY_XMEGA16D4)	+= xmega16d4_battery.o
>> +
>> diff --git a/drivers/power/supply/xmega16d4_battery.c b/drivers/power/supply/xmega16d4_battery.c
>> new file mode 100644
>> index 0000000..8c6b11a
>> --- /dev/null
>> +++ b/drivers/power/supply/xmega16d4_battery.c
>> @@ -0,0 +1,353 @@
>> +/*
>> + * Battery monitor driver for SL50 Toby Churchill SBS Batteries
>> + *
>> + * Copyright (c) 2017, Collabora Ltd.
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms and conditions of the GNU General Public License,
>> + * version 2, as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>.
>> + */
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/power_supply.h>
>> +#include <linux/spi/spi.h>
>> +#include <linux/workqueue.h>
>> +
>> +#define SBS_MEMORY_MAP_SIZE		128
>> +/* Charging voltage, 2 bytes */
>> +#define SBS_CHARGING_VOLTAGE		0x0a
>> +/* Design voltage, 2 bytes */
>> +#define SBS_DESIGN_VOLTAGE		0x0c
>> +/* Fast charging current, 2 bytes */
>> +#define SBS_FAST_CHARGING_CURRENT	0x0e
>> +/* Max T, Low T, 2 bytes */
>> +#define SBS_MAX_LOW_TEMPERATURE		0x10
>> +/* Pack capacity, 2 bytes */
>> +#define SBS_PACK_CAPACITY		0x12
>> +/* Serial number, 2 bytes */
>> +#define SBS_SERIAL_NUMBER		0x18
>> +/* Manufacturer name, 16 bytes */
>> +#define SBS_MANUFACTURER_NAME		0x20
>> +/* Model name, 16 bytes */
>> +#define SBS_MODEL_NAME			0x30
>> +/* Device chemistry, 5 bytes */
>> +#define SBS_DEVICE_CHEMISTRY		0x40
>> +/* Cycle count, 2 bytes */
>> +#define SBS_CYCLE_COUNT			0x50
>> +/* Voltage now, 2 bytes */
>> +#define SBS_VOLTAGE_NOW			0x70
>> +/* Current now, 2 bytes */
>> +#define SBS_CURRENT_NOW			0x72
>> +/* Battery Status, 2 bytes */
>> +#define SBS_BATTERY_STATUS		0x74
>> +# define BATTERY_STATUS_CHARGING	0
>> +# define BATTERY_STATUS_DISCHARGING	BIT(6)
>> +# define BATTERY_STATUS_FULLY_CHARGED	BIT(5)
>> +/* State of charge in percentage, 1 byte */
>> +#define SBS_STATE_OF_CHARGE		0x76
>> +
>> +/* MM SIZE + START(u16) + CHECKSUM(u16) */
>> +#define SPI_MSG_LENGTH		(SBS_MEMORY_MAP_SIZE + 4)
>> +#define SPI_MSG_DATA_BP		2
>> +/* MSB checksum byte position */
>> +#define SPI_MSG_CSUM_BP		(2 + SBS_MEMORY_MAP_SIZE)
>> +#define SPI_MSG_START_TOKEN	0xb00b
>> +
>> +struct xmega16d4_battery_data {
>> +	struct spi_device *spi;
>> +	struct power_supply *bat;
>> +
>> +	struct mutex		work_lock; /* protect work data */
>> +	struct delayed_work	bat_work;
>> +
>> +	u8 map[SBS_MEMORY_MAP_SIZE];
>> +
>> +	char model_name[16];
>> +	char manufacturer_name[16];
>> +	char serial_number[5];
>> +
>> +	int technology;
>> +	int voltage_uV;			/* units of uV */
>> +	int current_uA;			/* units of uA */
>> +	int rated_capacity;		/* units of µAh */
>> +	int cycle_count;
>> +	int rem_capacity;		/* percentage */
>> +	int life_sec;			/* units of seconds */
>> +	int status;			/* state of charge */
>> +};
>> +
>> +#define MAX_KEYLENGTH 256
>> +struct battery_property_map {
>> +	int value;
>> +	char const *key;
>> +};
>> +
>> +static struct battery_property_map map_technology[] = {
>> +	{ POWER_SUPPLY_TECHNOLOGY_NiMH, "NiMH" },
>> +	{ POWER_SUPPLY_TECHNOLOGY_LION, "LION" },
>> +	{ POWER_SUPPLY_TECHNOLOGY_LIPO, "LIPO" },
>> +	{ POWER_SUPPLY_TECHNOLOGY_LiFe, "LiFe" },
>> +	{ POWER_SUPPLY_TECHNOLOGY_NiCd, "NiCd" },
>> +	{ POWER_SUPPLY_TECHNOLOGY_LiMn, "LiMn" },
>> +	{ -1,				NULL   },
>> +};
>> +
>> +static int map_get_value(struct battery_property_map *map, const char *key,
>> +			 int def_val)
>> +{
>> +	char buf[MAX_KEYLENGTH];
>> +	int cr;
>> +
>> +	strncpy(buf, key, MAX_KEYLENGTH);
>> +	buf[MAX_KEYLENGTH - 1] = '\0';
>> +
>> +	cr = strnlen(buf, MAX_KEYLENGTH) - 1;
>> +	if (buf[cr] == '\n')
>> +		buf[cr] = '\0';
>> +
>> +	while (map->key) {
>> +		if (strncasecmp(map->key, buf, MAX_KEYLENGTH) == 0)
>> +			return map->value;
>> +		map++;
>> +	}
>> +
>> +	return def_val;
>> +}
>> +
>> +static int xmega16d4_battery_read_status(struct xmega16d4_battery_data *data)
>> +{
>> +	int i;
>> +	int csum = 0;
>> +	u8 buf[SBS_MEMORY_MAP_SIZE], technology[5];
>> +	unsigned int uval;
>> +	int sval;
>> +	struct spi_device *spi = data->spi;
>> +
>> +	for (i = 0; i < SBS_MEMORY_MAP_SIZE; i++) {
>> +		spi_write(spi, &i, 1);
>> +		spi_read(spi, &buf[i], 1);
> 
> spi_write_then_read(spi, &i, 1, &buf[i], 1)
> if (err)
>     complain
> 

Hmm, how odd, it works with

  err = spi_write(
  if (err)
    complain
  err = spi_read(
  if (err)
    complain

But not with
  err = spi_write_then_read(
  if (err)
     complain

I'm wondering what's the difference. I need to debug a bit this thing before
send v2.


>> +	}
>> +
>> +	print_hex_dump(KERN_DEBUG, ": ", DUMP_PREFIX_OFFSET, 16, 1,
>> +		       buf, SBS_MEMORY_MAP_SIZE, false);
>> +
>> +	/* Calculate the data checksum */
>> +	for (i = 0; i < SBS_MEMORY_MAP_SIZE - 2; i++)
>> +		csum += buf[i];
>> +
>> +	/* Verify the checksum */
>> +	uval = (buf[SBS_MEMORY_MAP_SIZE - 2] << 8) |
>> +		buf[SBS_MEMORY_MAP_SIZE - 1];
>> +	if (csum != uval) {
>> +		dev_dbg(&spi->dev,
>> +			"message received with invalid checksum (%d != %d)\n",
>> +			csum, uval);
>> +		return -ENOMSG;
> 
> dev_dbg? So it happens regularly?
> 

Right, should be dev_err, also I think I'll move the print_hex_dump here and
just print the dump if it fails (and replace for print_hex_dump_debug)

>> +	}
>> +
>> +	/* Update memory map with the new data */
>> +	memcpy(data->map, buf, SBS_MEMORY_MAP_SIZE);
>> +
>> +	strncpy(data->model_name, &data->map[SBS_MODEL_NAME], 16);
>> +
>> +	strncpy(data->manufacturer_name, &data->map[SBS_MANUFACTURER_NAME],
>> +		16);
>> +
>> +	strncpy(technology, &data->map[SBS_DEVICE_CHEMISTRY], 5);
>> +
>> +	uval = (u16)((data->map[SBS_SERIAL_NUMBER + 1] << 8) |
>> +		data->map[SBS_SERIAL_NUMBER]);
>> +	snprintf(data->serial_number, ARRAY_SIZE(data->serial_number), "%04d",
>> +		 uval);
>> +
>> +	data->technology = map_get_value(map_technology, technology,
>> +					 POWER_SUPPLY_TECHNOLOGY_UNKNOWN);
>> +
>> +	data->voltage_uV = (u16)((data->map[SBS_VOLTAGE_NOW + 1] << 8) |
>> +			    data->map[SBS_VOLTAGE_NOW]);
>> +	data->voltage_uV *= 1000;	/* convert from mV to uV */
>> +
>> +	sval = (s16)((data->map[SBS_CURRENT_NOW + 1] << 8) |
>> +		data->map[SBS_CURRENT_NOW]);
>> +	data->current_uA = sval;
>> +	data->current_uA *= 1000;	/* convert from mA to uA */
>> +
>> +	data->rated_capacity = (u16)((data->map[SBS_PACK_CAPACITY + 1] << 8) |
>> +				data->map[SBS_PACK_CAPACITY]);
>> +	data->rated_capacity *= 1000;	/* convert from mAh to uAh */
>> +
>> +	uval = (u16)((data->map[SBS_BATTERY_STATUS + 1] << 8) |
>> +		data->map[SBS_BATTERY_STATUS]);
>> +	if (uval == BATTERY_STATUS_CHARGING)
>> +		data->status = POWER_SUPPLY_STATUS_CHARGING;
>> +	else if (uval == BATTERY_STATUS_DISCHARGING)
>> +		data->status = POWER_SUPPLY_STATUS_DISCHARGING;
>> +	else if (uval == BATTERY_STATUS_FULLY_CHARGED)
>> +		data->status = POWER_SUPPLY_STATUS_FULL;
>> +	else
>> +		data->status = POWER_SUPPLY_STATUS_UNKNOWN;
>> +
>> +	data->cycle_count = (u16)((data->map[SBS_CYCLE_COUNT + 1] << 8) |
>> +			     data->map[SBS_CYCLE_COUNT]);
>> +
>> +	data->rem_capacity = data->map[SBS_STATE_OF_CHARGE];
>> +
>> +	uval = (data->rem_capacity * (data->rated_capacity / 1000)) / 100;
>> +	if (data->current_uA)
>> +		data->life_sec = (3600l * uval) / (data->current_uA / 1000);
> 
> looks like the driver would benefit from regmap.
> 
>> +	return 0;
>> +}
>> +
>> +static void xmega16d4_battery_work(struct work_struct *work)
>> +{
>> +	struct xmega16d4_battery_data *data = container_of(work,
>> +		struct xmega16d4_battery_data, bat_work.work);
>> +
>> +	/* Update values */
>> +	mutex_lock(&data->work_lock);
>> +	xmega16d4_battery_read_status(data);
>> +	mutex_unlock(&data->work_lock);
>> +
>> +	schedule_delayed_work(&data->bat_work, HZ * 60);
>> +}
>> +
>> +static int xmega16d4_battery_get_property(struct power_supply *psy,
>> +					  enum power_supply_property psp,
>> +					  union power_supply_propval *val)
>> +{
>> +	struct xmega16d4_battery_data *data = power_supply_get_drvdata(psy);
>> +
>> +	switch (psp) {
>> +	case POWER_SUPPLY_PROP_STATUS:
>> +		val->intval = data->status;
>> +		break;
>> +	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
>> +		val->intval = data->voltage_uV;
>> +		break;
>> +	case POWER_SUPPLY_PROP_CURRENT_NOW:
>> +		val->intval = data->current_uA;
>> +		break;
>> +	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
>> +		val->intval = data->rated_capacity;
>> +		break;
>> +	case POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW:
>> +		val->intval = data->life_sec;
>> +		break;
>> +	case POWER_SUPPLY_PROP_CAPACITY:
>> +		val->intval = data->rem_capacity;
>> +		break;
>> +	case POWER_SUPPLY_PROP_TECHNOLOGY:
>> +		val->intval = data->technology;
>> +		break;
>> +	case POWER_SUPPLY_PROP_MODEL_NAME:
>> +		val->strval = data->model_name;
>> +		break;
>> +	case POWER_SUPPLY_PROP_MANUFACTURER:
>> +		val->strval = data->manufacturer_name;
>> +		break;
>> +	case POWER_SUPPLY_PROP_SERIAL_NUMBER:
>> +		val->strval = data->serial_number;
>> +		break;
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static enum power_supply_property xmega16d4_battery_props[] = {
>> +	POWER_SUPPLY_PROP_STATUS,
>> +	POWER_SUPPLY_PROP_VOLTAGE_NOW,
>> +	POWER_SUPPLY_PROP_CURRENT_NOW,
>> +	POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
>> +	POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW,
>> +	POWER_SUPPLY_PROP_CAPACITY,
>> +	POWER_SUPPLY_PROP_TECHNOLOGY,
>> +	/* Properties of type `const char *' */
>> +	POWER_SUPPLY_PROP_MODEL_NAME,
>> +	POWER_SUPPLY_PROP_MANUFACTURER,
>> +	POWER_SUPPLY_PROP_SERIAL_NUMBER,
>> +};
>> +
>> +static const struct power_supply_desc xmega16d4_battery_desc = {
>> +	.name			= "battery-monitor",
>> +	.type			= POWER_SUPPLY_TYPE_BATTERY,
>> +	.properties		= xmega16d4_battery_props,
>> +	.num_properties		= ARRAY_SIZE(xmega16d4_battery_props),
>> +	.get_property		= xmega16d4_battery_get_property,
>> +};
>> +
>> +static int xmega16d4_battery_probe(struct spi_device *spi)
>> +{
>> +	struct xmega16d4_battery_data *data;
>> +	struct power_supply_config psy_cfg = {};
>> +
>> +	data = devm_kzalloc(&spi->dev, sizeof(*data), GFP_KERNEL);
>> +	if (!data)
>> +		return -ENOMEM;
>> +
>> +	data->spi = spi;
>> +	psy_cfg.of_node = spi->dev.of_node;
>> +	psy_cfg.drv_data = data;
>> +
>> +	mutex_init(&data->work_lock);
>> +
>> +	INIT_DELAYED_WORK(&data->bat_work, xmega16d4_battery_work);
>> +
>> +	spi_set_drvdata(spi, data);
>> +
>> +	/* Get initial status */
>> +	if (xmega16d4_battery_read_status(data))
>> +		return -ENODEV;
>> +
>> +	data->bat = devm_power_supply_register(&spi->dev,
>> +					       &xmega16d4_battery_desc,
>> +					       &psy_cfg);
>> +	if (IS_ERR(data->bat))
>> +		return PTR_ERR(data->bat);
>> +
>> +	schedule_delayed_work(&data->bat_work, 0);
>> +
>> +	return 0;
>> +}
>> +
>> +static int xmega16d4_battery_remove(struct spi_device *spi)
>> +{
>> +	struct xmega16d4_battery_data *data = spi_get_drvdata(spi);
>> +
>> +	cancel_delayed_work_sync(&data->bat_work);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct of_device_id xmega16d4_battery_of_match[] = {
>> +	{ .compatible = "tcl,xmega16d4-battery", },
>> +	{ /* sentinel */ },
>> +};
>> +
>> +static struct spi_driver xmega16d4_battery_driver = {
>> +	.driver = {
>> +		.name		= "xmega16d4-battery",
>> +		.owner		= THIS_MODULE,
>> +		.of_match_table = of_match_ptr(xmega16d4_battery_of_match),
> 
> Either put xmega16d4_battery_of_match inside of #ifdef CONFIG_OF
> or drop of_match_ptr. Otherwise there will be an unused warning
> for the CONFIG_OF=n case.
> 

Ok

>> +	},
>> +	.probe	= xmega16d4_battery_probe,
>> +	.remove	= xmega16d4_battery_remove,
>> +};
>> +module_spi_driver(xmega16d4_battery_driver);
>> +
>> +MODULE_ALIAS("spi:xmega16d4-battery");
>> +
>> +MODULE_LICENSE("GPL v2");
>> +MODULE_AUTHOR("Enric Balletbo Serra <enric.balletbo@...labora.com>");
>> +MODULE_DESCRIPTION("xmega16d4 battery monitor driver");
> 
> Otherwise the driver looks fine. I'm a bit worried about the name,
> though. xmega16d4 is just a microcontroller. This driver is more
> about its firmware. I think something like "toby-churchill-battery-monitor"
> would be better.
> 

It's not a problem rename the driver, I'm thinking in tcl-sbs-battery if it's
fine, a bit shorted that the one you proposed.

> -- Sebastian
> 
Thanks,
 Enric

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