[RFC,2/5] mfd: bq257xx: Add support for BQ25703 core driver

From: Chris Morgan <macromorgan@hotmail.com>

The Texas Instruments BQ25703A is an integrated charger manager and
boost converter.

The MFD driver initalizes the device for the regulator driver
and power supply driver.

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
---
 drivers/mfd/Kconfig         |  11 ++++
 drivers/mfd/Makefile        |   1 +
 drivers/mfd/bq257xx.c       | 118 +++++++++++++++++++++++++++++++++++
 include/linux/mfd/bq257xx.h | 120 ++++++++++++++++++++++++++++++++++++
 4 files changed, 250 insertions(+)
 create mode 100644 drivers/mfd/bq257xx.c
 create mode 100644 include/linux/mfd/bq257xx.h

On Thu, 29 Aug 2024, Chris Morgan wrote:

> From: Chris Morgan <macromorgan@hotmail.com>
> 
> The Texas Instruments BQ25703A is an integrated charger manager and
> boost converter.
> 
> The MFD driver initalizes the device for the regulator driver
> and power supply driver.
> 
> Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
> ---
>  drivers/mfd/Kconfig         |  11 ++++
>  drivers/mfd/Makefile        |   1 +
>  drivers/mfd/bq257xx.c       | 118 +++++++++++++++++++++++++++++++++++
>  include/linux/mfd/bq257xx.h | 120 ++++++++++++++++++++++++++++++++++++
>  4 files changed, 250 insertions(+)
>  create mode 100644 drivers/mfd/bq257xx.c
>  create mode 100644 include/linux/mfd/bq257xx.h
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index bc8be2e593b6..712951ae7341 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -1537,6 +1537,17 @@ config MFD_TI_LMU
>  	  LM36274.  It consists of backlight, LED and regulator driver.
>  	  It provides consistent device controls for lighting functions.
>  
> +config MFD_BQ257XX
> +	tristate "TI BQ257XX Buck/Boost Charge Controller"
> +	depends on I2C
> +	select MFD_CORE
> +	select REGMAP_I2C
> +	help
> +	  Support Texas Instruments BQ25703 Buck/Boost converter with
> +	  charge controller. It consists of regulators that provide
> +	  system voltage and OTG voltage, and a charger manager for
> +	  batteries containing one or more cells.
> +
>  config MFD_OMAP_USB_HOST
>  	bool "TI OMAP USBHS core and TLL driver"
>  	depends on USB_EHCI_HCD_OMAP || USB_OHCI_HCD_OMAP3
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 02b651cd7535..90bc65d83c5f 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -13,6 +13,7 @@ obj-$(CONFIG_MFD_SM501)		+= sm501.o
>  obj-$(CONFIG_ARCH_BCM2835)	+= bcm2835-pm.o
>  obj-$(CONFIG_MFD_BCM590XX)	+= bcm590xx.o
>  obj-$(CONFIG_MFD_BD9571MWV)	+= bd9571mwv.o
> +obj-$(CONFIG_MFD_BQ257XX)	+= bq257xx.o
>  obj-$(CONFIG_MFD_CROS_EC_DEV)	+= cros_ec_dev.o
>  obj-$(CONFIG_MFD_CS42L43)	+= cs42l43.o
>  obj-$(CONFIG_MFD_CS42L43_I2C)	+= cs42l43-i2c.o
> diff --git a/drivers/mfd/bq257xx.c b/drivers/mfd/bq257xx.c
> new file mode 100644
> index 000000000000..c612262f9a1e
> --- /dev/null
> +++ b/drivers/mfd/bq257xx.c
> @@ -0,0 +1,118 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* BQ257XX MFD Driver

The top line of a multi-line comment should be empty.

Please drop _all_ mentions of "MFD" - it's not a thing.

> + * Copyright (C) 2024 Chris Morgan <macromorgan@hotmail.com>

'\n' here.

> + * Based off of BQ256XX Battery Charger Driver and
> + * Rockchip RK808 MFD Driver

You really don't have to mention this.

9 out of every 10 (I just made those figures up) drivers in the kernel
take inspiration from existing ones.  These sentences don't add
anything IMHO.

> + */
> +
> +#include <linux/device.h>
> +#include <linux/i2c.h>
> +#include <linux/mfd/bq257xx.h>
> +#include <linux/mfd/core.h>
> +#include <linux/regmap.h>
> +
> +static const struct regmap_range bq25703_readonly_reg_ranges[] = {
> +	regmap_reg_range(BQ25703_CHARGER_STATUS, BQ25703_MANUFACT_DEV_ID),
> +};
> +
> +static const struct regmap_access_table bq25703_writeable_regs = {
> +	.no_ranges = bq25703_readonly_reg_ranges,
> +	.n_no_ranges = ARRAY_SIZE(bq25703_readonly_reg_ranges),
> +};
> +
> +static const struct regmap_range bq25703_volatile_reg_ranges[] = {
> +	regmap_reg_range(BQ25703_CHARGE_OPTION_0, BQ25703_IIN_HOST),
> +	regmap_reg_range(BQ25703_CHARGER_STATUS, BQ25703_ADC_OPTION),
> +};
> +
> +static const struct regmap_access_table bq25703_volatile_regs = {
> +	.yes_ranges = bq25703_volatile_reg_ranges,
> +	.n_yes_ranges = ARRAY_SIZE(bq25703_volatile_reg_ranges),
> +};
> +
> +static const struct regmap_config bq25703_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 16,
> +	.max_register = BQ25703_ADC_OPTION,
> +	.cache_type = REGCACHE_RBTREE,
> +	.wr_table = &bq25703_writeable_regs,
> +	.volatile_table = &bq25703_volatile_regs,
> +	.val_format_endian = REGMAP_ENDIAN_LITTLE,
> +};
> +
> +static const struct mfd_cell bq25703_cells[] = {
> +	MFD_CELL_NAME("bq257xx-regulator"),
> +	MFD_CELL_NAME("bq257xx-charger"),
> +};
> +
> +static int bq257xx_probe(struct i2c_client *client)
> +{
> +	struct device *dev = &client->dev;
> +	struct bq257xx_device *bq;

Call this ddata.

> +	const struct mfd_cell *cells;
> +	int nr_cells;
> +	int ret = 0;

The pre-initialisation is redundant.

> +	bq = devm_kzalloc(dev, sizeof(*bq), GFP_KERNEL);
> +	if (!bq)
> +		return -ENOMEM;
> +
> +	bq->client = client;
> +	bq->dev = dev;

You don't need both.

> +	bq->variant = (long)i2c_get_match_data(client);

Pretty sure this cast is not correct and maybe not even required.

> +	switch (bq->variant) {
> +	case BQ25703A:

I wouldn't add all of this complexity until its needed.

> +		bq->regmap_cfg = &bq25703_regmap_config;

Where is this consumed?

> +		cells = bq25703_cells;
> +		nr_cells = ARRAY_SIZE(bq25703_cells);
> +		break;
> +	default:
> +		dev_err(dev, "Unsupported BQ257XX ID %ld\n", bq->variant);
> +		return -EINVAL;
> +	}
> +
> +	bq->regmap = devm_regmap_init_i2c(client, bq->regmap_cfg);
> +

Remove this line.

> +	if (IS_ERR(bq->regmap)) {
> +		dev_err(dev, "Failed to allocate register map\n");
> +		return PTR_ERR(bq->regmap);
> +	}
> +
> +	i2c_set_clientdata(client, bq);
> +
> +	ret = devm_mfd_add_devices(&client->dev, PLATFORM_DEVID_AUTO,
> +				   cells, nr_cells, NULL, 0, NULL);
> +	if (ret) {
> +		dev_err(&client->dev, "failed to add MFD devices %d\n", ret);

No such thing.

"Failed to register child devices"
q
> +		return ret;
> +	}
> +
> +	return ret;
> +}
> +
> +static const struct i2c_device_id bq257xx_i2c_ids[] = {
> +	{ "bq25703a" },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, bq257xx_i2c_ids);
> +
> +static const struct of_device_id bq257xx_of_match[] = {
> +	{ .compatible = "ti,bq25703a", .data = (void *)BQ25703A, },

Cast almost certainly not required.

> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, bq257xx_of_match);
> +
> +static struct i2c_driver bq257xx_driver = {
> +	.driver = {
> +		.name = "bq257xx",
> +		.of_match_table = bq257xx_of_match,
> +	},
> +	.probe = bq257xx_probe,
> +	.id_table = bq257xx_i2c_ids,
> +};
> +module_i2c_driver(bq257xx_driver);
> +
> +MODULE_DESCRIPTION("bq257xx buck/boost/charger MFD driver");

Not an "MFD driver"

> +MODULE_AUTHOR("Chris Morgan <macromorgan@hotmail.com>");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/mfd/bq257xx.h b/include/linux/mfd/bq257xx.h
> new file mode 100644
> index 000000000000..51f6501c6441
> --- /dev/null
> +++ b/include/linux/mfd/bq257xx.h
> @@ -0,0 +1,120 @@
> +/* SPDX-License-Identifier: GPL-2.0
> + * Register definitions for TI BQ257XX
> + * Heavily based off of BQ256XX Battery Charger Driver
> + * Copyright (C) 2020 Texas Instruments Incorporated - http://www.ti.com/
> + */

All as above.

> +#define BQ257XX_MANUFACTURER			"Texas Instruments"

Errr, no thank you.  Just use strings where you need them.

> +#define BQ25703_CHARGE_OPTION_0			0x00
> +#define BQ25703_CHARGE_CURRENT			0x02
> +#define BQ25703_MAX_CHARGE_VOLT			0x04
> +#define BQ25703_OTG_VOLT			0x06
> +#define BQ25703_OTG_CURRENT			0x08
> +#define BQ25703_INPUT_VOLTAGE			0x0a
> +#define BQ25703_MIN_VSYS			0x0c
> +#define BQ25703_IIN_HOST			0x0e
> +#define BQ25703_CHARGER_STATUS			0x20
> +#define BQ25703_PROCHOT_STATUS			0x22
> +#define BQ25703_IIN_DPM				0x24
> +#define BQ25703_ADCIBAT_CHG			0x28
> +#define BQ25703_ADCIINCMPIN			0x2a
> +#define BQ25703_ADCVSYSVBAT			0x2c
> +#define BQ25703_MANUFACT_DEV_ID			0x2e
> +#define BQ25703_CHARGE_OPTION_1			0x30
> +#define BQ25703_CHARGE_OPTION_2			0x32
> +#define BQ25703_CHARGE_OPTION_3			0x34
> +#define BQ25703_ADC_OPTION			0x3a
> +
> +#define BQ25703_EN_LWPWR			BIT(15)
> +#define BQ25703_WDTMR_ADJ_MASK			GENMASK(14, 13)
> +#define BQ25703_WDTMR_DISABLE			0
> +#define BQ25703_WDTMR_5_SEC			1
> +#define BQ25703_WDTMR_88_SEC			2
> +#define BQ25703_WDTMR_175_SEC			3
> +
> +#define BQ25703_ICHG_MASK			GENMASK(12, 6)
> +#define BQ25703_ICHG_STEP_UA			64000
> +#define BQ25703_ICHG_MIN_UA			64000
> +#define BQ25703_ICHG_MAX_UA			8128000
> +
> +#define BQ25703_MAX_CHARGE_VOLT_MASK		GENMASK(15, 4)
> +#define BQ25703_VBATREG_STEP_UV			16000
> +#define BQ25703_VBATREG_MIN_UV			1024000
> +#define BQ25703_VBATREG_MAX_UV			19200000
> +
> +#define BQ25703_OTG_VOLT_MASK			GENMASK(13, 6)
> +#define BQ25703_OTG_VOLT_STEP_UV		64000
> +#define BQ25703_OTG_VOLT_MIN_UV			4480000
> +#define BQ25703_OTG_VOLT_MAX_UV			20800000
> +#define BQ25703_OTG_VOLT_NUM_VOLT		256
> +
> +#define BQ25703_OTG_CUR_MASK			GENMASK(14, 8)
> +#define BQ25703_OTG_CUR_STEP_UA			50000
> +#define BQ25703_OTG_CUR_MAX_UA			6350000
> +
> +#define BQ25703_MINVSYS_MASK			GENMASK(13, 8)
> +#define BQ25703_MINVSYS_STEP_UV			256000
> +#define BQ25703_MINVSYS_MIN_UV			1024000
> +#define BQ25703_MINVSYS_MAX_UV			16128000
> +
> +#define BQ25703_STS_AC_STAT			BIT(15)
> +#define BQ25703_STS_IN_FCHRG			BIT(10)
> +#define BQ25703_STS_IN_PCHRG			BIT(9)
> +#define BQ25703_STS_FAULT_ACOV			BIT(7)
> +#define BQ25703_STS_FAULT_BATOC			BIT(6)
> +#define BQ25703_STS_FAULT_ACOC			BIT(5)
> +
> +#define BQ25703_IINDPM_MASK			GENMASK(14, 8)
> +#define BQ25703_IINDPM_STEP_UA			50000
> +#define BQ25703_IINDPM_MIN_UA			50000
> +#define BQ25703_IINDPM_MAX_UA			6400000
> +#define BQ25703_IINDPM_DEFAULT_UA		3300000
> +#define BQ25703_IINDPM_OFFSET_UA		50000
> +
> +#define BQ25703_ADCIBAT_DISCHG_MASK		GENMASK(6, 0)
> +#define BQ25703_ADCIBAT_CHG_MASK		GENMASK(14, 8)
> +#define BQ25703_ADCIBAT_CHG_STEP_UA		64000
> +#define BQ25703_ADCIBAT_DIS_STEP_UA		256000
> +
> +#define BQ25703_ADCIIN				GENMASK(15, 8)
> +#define BQ25703_ADCIINCMPIN_STEP		50000
> +
> +#define BQ25703_ADCVSYS_MASK			GENMASK(15, 8)
> +#define BQ25703_ADCVBAT_MASK			GENMASK(7, 0)
> +#define BQ25703_ADCVSYSVBAT_OFFSET_UV		2880000
> +#define BQ25703_ADCVSYSVBAT_STEP		64000
> +
> +#define BQ25703_ADC_CH_MASK			GENMASK(7, 0)
> +#define BQ25703_ADC_CONV_EN			BIT(15)
> +#define BQ25703_ADC_START			BIT(14)
> +#define BQ25703_ADC_FULL_SCALE			BIT(13)
> +#define BQ25703_ADC_CMPIN_EN			BIT(7)
> +#define BQ25703_ADC_VBUS_EN			BIT(6)
> +#define BQ25703_ADC_PSYS_EN			BIT(5)
> +#define BQ25703_ADC_IIN_EN			BIT(4)
> +#define BQ25703_ADC_IDCHG_EN			BIT(3)
> +#define BQ25703_ADC_ICHG_EN			BIT(2)
> +#define BQ25703_ADC_VSYS_EN			BIT(1)
> +#define BQ25703_ADC_VBAT_EN			BIT(0)
> +
> +#define BQ25703_EN_OTG_MASK			BIT(12)
> +
> +enum bq257xx_id {
> +	BQ25703A,
> +};
> +
> +/**

Are you sure you want to use kernel-doc here?

I would advise against it.

> + * struct bq257xx_device -
> + * @client: i2c client structure
> + * @regmap: register map structure
> + * @dev: device structure
> + * @regmap_cfg: device specific regmap cfg

It's also wrong.  Did you test build with W=1?

> + */
> +struct bq257xx_device {
> +	struct i2c_client *client;
> +	struct regmap *regmap;
> +	struct device *dev;
> +	const struct regmap_config *regmap_cfg;
> +	long variant;
> +};
> -- 
> 2.34.1
>