Date:   Thu, 14 Sep 2023 16:35:14 +0200
From:   Sebastian Reichel <sebastian.reichel@...labora.com>
To:     Nikita Travkin <nikita@...n.ru>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v2 3/4] power: supply: Add pm8916 VM-BMS support

Hi,

On Mon, Jul 31, 2023 at 10:06:26PM +0500, Nikita Travkin wrote:
> This driver adds basic support for VM-BMS found in pm8916.
> 
> VM-BMS is a very basic fuel-gauge hardware block that is, sadly,
> incapable of any gauging. The hardware supports measuring OCV in
> sleep mode, where the battery is not in use, or measuring average
> voltage over time when the device is active.
> 
> This driver implements basic value readout from this block.
> 
> Signed-off-by: Nikita Travkin <nikita@...n.ru>
> ---
> v2: Get irq by name
> ---

Thanks for the patch. I have a few small change requests.

>  drivers/power/supply/Kconfig         |  11 ++
>  drivers/power/supply/Makefile        |   1 +
>  drivers/power/supply/pm8916_bms_vm.c | 296 +++++++++++++++++++++++++++++++++++
>  3 files changed, 308 insertions(+)
> 
> diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
> index 663a1c423806..e93a5a4d03e2 100644
> --- a/drivers/power/supply/Kconfig
> +++ b/drivers/power/supply/Kconfig
> @@ -629,6 +629,17 @@ config CHARGER_QCOM_SMBB
>  	  documentation for more detail.  The base name for this driver is
>  	  'pm8941_charger'.
>  
> +config BATTERY_PM8916_BMS_VM
> +	tristate "Qualcomm PM8916 BMS-VM support"
> +	depends on MFD_SPMI_PMIC || COMPILE_TEST
> +	help
> +	  Say Y to add support for Voltage Mode BMS block found in some
> +	  Qualcomm PMICs such as PM8916. This hardware block provides
> +	  battery voltage monitoring for the system.
> +
> +	  To compile this driver as module, choose M here: the
> +	  module will be called pm8916_bms_vm.
> +
>  config CHARGER_BQ2415X
>  	tristate "TI BQ2415x battery charger driver"
>  	depends on I2C
> diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
> index a8a9fa6de1e9..fdf7916f80ed 100644
> --- a/drivers/power/supply/Makefile
> +++ b/drivers/power/supply/Makefile
> @@ -84,6 +84,7 @@ obj-$(CONFIG_CHARGER_MP2629)	+= mp2629_charger.o
>  obj-$(CONFIG_CHARGER_MT6360)	+= mt6360_charger.o
>  obj-$(CONFIG_CHARGER_MT6370)	+= mt6370-charger.o
>  obj-$(CONFIG_CHARGER_QCOM_SMBB)	+= qcom_smbb.o
> +obj-$(CONFIG_BATTERY_PM8916_BMS_VM)	+= pm8916_bms_vm.o
>  obj-$(CONFIG_CHARGER_BQ2415X)	+= bq2415x_charger.o
>  obj-$(CONFIG_CHARGER_BQ24190)	+= bq24190_charger.o
>  obj-$(CONFIG_CHARGER_BQ24257)	+= bq24257_charger.o
> diff --git a/drivers/power/supply/pm8916_bms_vm.c b/drivers/power/supply/pm8916_bms_vm.c
> new file mode 100644
> index 000000000000..6cf00bf1c466
> --- /dev/null
> +++ b/drivers/power/supply/pm8916_bms_vm.c
> @@ -0,0 +1,296 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2023, Nikita Travkin <nikita@...n.ru>
> + */
> +
> +#include <linux/errno.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>

You should be able to remove the of headers after my proposed
changes.

> +#include <linux/platform_device.h>
> +#include <linux/power_supply.h>
> +#include <linux/property.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +#include <linux/delay.h>
> +#include <linux/interrupt.h>
> +
> +#define PM8916_PERPH_TYPE 0x04
> +#define PM8916_BMS_VM_TYPE 0x020D
> +
> +#define PM8916_SEC_ACCESS 0xD0
> +#define PM8916_SEC_MAGIC 0xA5
> +
> +#define PM8916_BMS_VM_STATUS1 0x08
> +#define PM8916_BMS_VM_FSM_STATE(x) (((x) & 0b00111000) >> 3)
> +#define PM8916_BMS_VM_FSM_STATE_S2 0x2
> +
> +#define PM8916_BMS_VM_MODE_CTL 0x40
> +#define PM8916_BMS_VM_MODE_FORCE_S3 (BIT(0) | BIT(1))
> +#define PM8916_BMS_VM_MODE_NORMAL (BIT(1) | BIT(3))
> +
> +#define PM8916_BMS_VM_EN_CTL 0x46
> +#define PM8916_BMS_ENABLED BIT(7)
> +
> +#define PM8916_BMS_VM_FIFO_LENGTH_CTL 0x47
> +#define PM8916_BMS_VM_S1_SAMPLE_INTERVAL_CTL 0x55
> +#define PM8916_BMS_VM_S2_SAMPLE_INTERVAL_CTL 0x56
> +#define PM8916_BMS_VM_S3_S7_OCV_DATA0 0x6A
> +#define PM8916_BMS_VM_BMS_FIFO_REG_0_LSB 0xC0
> +
> +/* Using only 1 fifo is broken in hardware */
> +#define PM8916_BMS_VM_FIFO_COUNT 2 /* 2 .. 8 */
> +
> +#define PM8916_BMS_VM_S1_SAMPLE_INTERVAL 10
> +#define PM8916_BMS_VM_S2_SAMPLE_INTERVAL 10
> +
> +struct pm8916_bms_vm_battery {
> +	struct device *dev;
> +	struct power_supply *battery;
> +	struct power_supply_battery_info *info;
> +	struct regmap *regmap;
> +	unsigned int reg;
> +	unsigned int last_ocv;
> +	unsigned int vbat_now;
> +};
> +
> +static int pm8916_bms_vm_battery_get_property(struct power_supply *psy,
> +					      enum power_supply_property psp,
> +					      union power_supply_propval *val)
> +{
> +	struct pm8916_bms_vm_battery *bat = power_supply_get_drvdata(psy);
> +	struct power_supply_battery_info *info = bat->info;
> +	int supplied;
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_STATUS:
> +		supplied = power_supply_am_i_supplied(psy);
> +
> +		if (supplied < 0 && supplied != -ENODEV)
> +			return supplied;
> +		else if (supplied && supplied != -ENODEV)
> +			val->intval = POWER_SUPPLY_STATUS_CHARGING;
> +		else
> +			val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
> +		return 0;
> +
> +	case POWER_SUPPLY_PROP_HEALTH:
> +		if (bat->vbat_now < info->voltage_min_design_uv)
> +			val->intval = POWER_SUPPLY_HEALTH_DEAD;
> +		else if (bat->vbat_now > info->voltage_max_design_uv)
> +			val->intval = POWER_SUPPLY_HEALTH_OVERVOLTAGE;
> +		else
> +			val->intval = POWER_SUPPLY_HEALTH_GOOD;
> +		return 0;
> +
> +	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
> +		val->intval = bat->vbat_now;
> +		return 0;
> +
> +	case POWER_SUPPLY_PROP_VOLTAGE_BOOT:
> +		/* Returning last known ocv value here - it changes after suspend. */
> +		val->intval = bat->last_ocv;
> +		return 0;

Returning OCV from last suspend is not the same as VOLTAGE_BOOT. How
about exposing POWER_SUPPLY_PROP_VOLTAGE_OCV and returning -ENODATA
if the value is older than 180 seconds?

> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static enum power_supply_property pm8916_bms_vm_battery_properties[] = {
> +	POWER_SUPPLY_PROP_STATUS,
> +	POWER_SUPPLY_PROP_VOLTAGE_NOW,
> +	POWER_SUPPLY_PROP_VOLTAGE_BOOT,
> +	POWER_SUPPLY_PROP_HEALTH,
> +};
> +
> +static irqreturn_t pm8916_bms_vm_fifo_update_done_irq(int irq, void *data)
> +{
> +	struct pm8916_bms_vm_battery *bat = data;
> +	u16 vbat_data[PM8916_BMS_VM_FIFO_COUNT];
> +	int ret;
> +
> +	ret = regmap_bulk_read(bat->regmap, bat->reg + PM8916_BMS_VM_BMS_FIFO_REG_0_LSB,
> +			       &vbat_data, PM8916_BMS_VM_FIFO_COUNT * 2);
> +	if (ret)
> +		return IRQ_HANDLED;
> +
> +	/*
> +	 * The VM-BMS hardware only collects voltage data and the software
> +	 * has to process it to calculate the OCV and SoC. Hardware provides
> +	 * up to 8 averaged measurements for software to take in account.
> +	 *
> +	 * Just use the last measured value for now to report the current
> +	 * battery voltage.
> +	 */
> +	bat->vbat_now = vbat_data[PM8916_BMS_VM_FIFO_COUNT - 1] * 300;
> +
> +	power_supply_changed(bat->battery);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static const struct power_supply_desc pm8916_bms_vm_battery_psy_desc = {
> +	.name = "pm8916-bms-vm",
> +	.type = POWER_SUPPLY_TYPE_BATTERY,
> +	.properties = pm8916_bms_vm_battery_properties,
> +	.num_properties = ARRAY_SIZE(pm8916_bms_vm_battery_properties),
> +	.get_property = pm8916_bms_vm_battery_get_property,
> +};
> +
> +static int pm8916_bms_vm_battery_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct pm8916_bms_vm_battery *bat;
> +	struct power_supply_config psy_cfg = {};
> +	int ret, irq;
> +	unsigned int tmp;
> +
> +	bat = devm_kzalloc(dev, sizeof(*bat), GFP_KERNEL);
> +	if (!bat)
> +		return -ENOMEM;
> +
> +	bat->dev = dev;
> +
> +	bat->regmap = dev_get_regmap(pdev->dev.parent, NULL);
> +	if (!bat->regmap)
> +		return -ENODEV;
> +
> +	of_property_read_u32(dev->of_node, "reg", &bat->reg);

device_property_read_u32(...)

> +	if (bat->reg < 0)
> +		return -EINVAL;
> +
> +	irq = platform_get_irq_byname(pdev, "fifo");
> +	if (irq < 0)
> +		return irq;
> +
> +	ret = devm_request_threaded_irq(dev, irq, NULL, pm8916_bms_vm_fifo_update_done_irq,
> +					IRQF_ONESHOT, "pm8916_vm_bms", bat);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_bulk_read(bat->regmap, bat->reg + PM8916_PERPH_TYPE, &tmp, 2);
> +	if (ret)
> +		goto comm_error;
> +
> +	if (tmp != PM8916_BMS_VM_TYPE)
> +		return dev_err_probe(dev, -ENODEV, "Device reported wrong type: 0x%X\n", tmp);
> +
> +	ret = regmap_write(bat->regmap, bat->reg + PM8916_BMS_VM_S1_SAMPLE_INTERVAL_CTL,
> +			   PM8916_BMS_VM_S1_SAMPLE_INTERVAL);
> +	if (ret)
> +		goto comm_error;
> +	ret = regmap_write(bat->regmap, bat->reg + PM8916_BMS_VM_S2_SAMPLE_INTERVAL_CTL,
> +			   PM8916_BMS_VM_S2_SAMPLE_INTERVAL);
> +	if (ret)
> +		goto comm_error;
> +	ret = regmap_write(bat->regmap, bat->reg + PM8916_BMS_VM_FIFO_LENGTH_CTL,
> +			   PM8916_BMS_VM_FIFO_COUNT << 4 | PM8916_BMS_VM_FIFO_COUNT);
> +	if (ret)
> +		goto comm_error;
> +	ret = regmap_write(bat->regmap,
> +			   bat->reg + PM8916_BMS_VM_EN_CTL, PM8916_BMS_ENABLED);
> +	if (ret)
> +		goto comm_error;
> +
> +	ret = regmap_bulk_read(bat->regmap,
> +			       bat->reg + PM8916_BMS_VM_S3_S7_OCV_DATA0, &tmp, 2);
> +	if (ret)
> +		goto comm_error;
> +
> +	bat->last_ocv = tmp * 300;
> +	bat->vbat_now = bat->last_ocv;
> +
> +	psy_cfg.drv_data = bat;
> +	psy_cfg.of_node = dev->of_node;
> +
> +	bat->battery = devm_power_supply_register(dev, &pm8916_bms_vm_battery_psy_desc, &psy_cfg);
> +	if (IS_ERR(bat->battery))
> +		return dev_err_probe(dev, PTR_ERR(bat->battery), "Unable to register battery\n");
> +
> +	ret = power_supply_get_battery_info(bat->battery, &bat->info);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Unable to get battery info\n");
> +
> +	platform_set_drvdata(pdev, bat);
> +
> +	return 0;
> +
> +comm_error:
> +	return dev_err_probe(dev, ret, "Unable to communicate with device\n");
> +}
> +
> +static int pm8916_bms_vm_battery_suspend(struct platform_device *pdev, pm_message_t state)
> +{
> +	struct pm8916_bms_vm_battery *bat = platform_get_drvdata(pdev);
> +	int ret;
> +
> +	/*
> +	 * Due to a hardware quirk the FSM doesn't switch states normally.
> +	 * Instead we unlock the debug registers and force S3 (Measure OCV/Sleep)
> +	 * mode every time we suspend.
> +	 */
> +
> +	ret = regmap_write(bat->regmap,
> +			   bat->reg + PM8916_SEC_ACCESS, PM8916_SEC_MAGIC);
> +	if (ret)
> +		goto error;
> +	ret = regmap_write(bat->regmap,
> +			   bat->reg + PM8916_BMS_VM_MODE_CTL, PM8916_BMS_VM_MODE_FORCE_S3);
> +	if (ret)
> +		goto error;
> +
> +	return 0;
> +
> +error:
> +	dev_err(bat->dev, "Failed to force S3 mode: %pe\n", ERR_PTR(ret));
> +	return ret;
> +}
> +
> +static int pm8916_bms_vm_battery_resume(struct platform_device *pdev)
> +{
> +	struct pm8916_bms_vm_battery *bat = platform_get_drvdata(pdev);
> +	int ret;
> +	unsigned int tmp;
> +
> +	ret = regmap_bulk_read(bat->regmap,
> +			       bat->reg + PM8916_BMS_VM_S3_S7_OCV_DATA0, &tmp, 2);
> +
> +	bat->last_ocv = tmp * 300;
> +
> +	ret = regmap_write(bat->regmap,
> +			   bat->reg + PM8916_SEC_ACCESS, PM8916_SEC_MAGIC);
> +	if (ret)
> +		goto error;
> +	ret = regmap_write(bat->regmap,
> +			   bat->reg + PM8916_BMS_VM_MODE_CTL, PM8916_BMS_VM_MODE_NORMAL);
> +	if (ret)
> +		goto error;
> +
> +	return 0;
> +
> +error:
> +	dev_err(bat->dev, "Failed to return normal mode: %pe\n", ERR_PTR(ret));
> +	return ret;
> +}
> +
> +static const struct of_device_id pm8916_bms_vm_battery_of_match[] = {
> +	{ .compatible = "qcom,pm8916-bms-vm", },
> +	{ },

{}

(i.e. remove space and trailing , for terminator entry)

> +};
> +MODULE_DEVICE_TABLE(of, pm8916_bms_vm_battery_of_match);
> +
> +static struct platform_driver pm8916_bms_vm_battery_driver = {
> +	.driver = {
> +		.name = "pm8916-bms-vm",
> +		.of_match_table = of_match_ptr(pm8916_bms_vm_battery_of_match),

remove of_match_ptr().

> +	},
> +	.probe = pm8916_bms_vm_battery_probe,
> +	.suspend = pm8916_bms_vm_battery_suspend,
> +	.resume = pm8916_bms_vm_battery_resume,
> +};
> +module_platform_driver(pm8916_bms_vm_battery_driver);
> +
> +MODULE_DESCRIPTION("pm8916 BMS-VM driver");
> +MODULE_AUTHOR("Nikita Travkin <nikita@...n.ru>");
> +MODULE_LICENSE("GPL");

Otherwise LGTM,

-- Sebastian

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