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Message-ID: <20151118234918.GD15481@beast>
Date:	Wed, 18 Nov 2015 17:49:22 -0600
From:	Andreas Dannenberg <dannenberg@...com>
To:	Ramakrishna Pallala <ramakrishna.pallala@...el.com>
CC:	<linux-kernel@...r.kernel.org>, <linux-pm@...r.kernel.org>,
	<devicetree@...r.kernel.org>, Sebastian Reichel <sre@...nel.org>,
	Jenny Tc <jenny.tc@...el.com>
Subject: Re: [PATCH 2/2] power: Add support for TI BQ24261 charger

Hi Ram,
I'm back in the battery charger game, please find additional feedback
below. Generally speaking I'd like us to pick up the work on this
driver again to get it over the hump. If you are B/W constrained I'd be
happy to take over the upstreaming process - your call. It's just like I
said earlier I'm on the hook providing support for bq24261M and bq24262
devices from a TI POV and this work is gating the progress on that
front.

On Thu, Oct 29, 2015 at 10:07:05PM +0530, Ramakrishna Pallala wrote:
> Add new charger driver support for TI BQ24261 charger IC.
> 
> TI BQ24261 charger driver relies on extcon notifications to get the
> charger cable type and based on that it will set the charging parameters.
> 
> Signed-off-by: Ramakrishna Pallala <ramakrishna.pallala@...el.com>
> Signed-off-by: Jenny TC <jenny.tc@...el.com>
> ---
>  drivers/power/Kconfig                 |    6 +
>  drivers/power/Makefile                |    1 +
>  drivers/power/bq24261_charger.c       | 1195 +++++++++++++++++++++++++++++++++
>  include/linux/power/bq24261_charger.h |   26 +
>  4 files changed, 1228 insertions(+)
>  create mode 100644 drivers/power/bq24261_charger.c
>  create mode 100644 include/linux/power/bq24261_charger.h
> 
> diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
> index cb0ae66..d817dd9 100644
> --- a/drivers/power/Kconfig
> +++ b/drivers/power/Kconfig
> @@ -408,6 +408,12 @@ config CHARGER_BQ24190
>  	help
>  	  Say Y to enable support for the TI BQ24190 battery charger.
>  
> +config CHARGER_BQ24261
> +	tristate "TI BQ24261 charger driver"
> +	depends on I2C && EXTCON
> +	help
> +	  Say Y here to enable support for TI BQ24261 battery charger.
> +
>  config CHARGER_BQ24257
>  	tristate "TI BQ24250/24251/24257 battery charger driver"
>  	depends on I2C
> diff --git a/drivers/power/Makefile b/drivers/power/Makefile
> index b0e1bf1..f59d8bd 100644
> --- a/drivers/power/Makefile
> +++ b/drivers/power/Makefile
> @@ -61,6 +61,7 @@ obj-$(CONFIG_CHARGER_MAX8998)	+= max8998_charger.o
>  obj-$(CONFIG_CHARGER_QCOM_SMBB)	+= qcom_smbb.o
>  obj-$(CONFIG_CHARGER_BQ2415X)	+= bq2415x_charger.o
>  obj-$(CONFIG_CHARGER_BQ24190)	+= bq24190_charger.o
> +obj-$(CONFIG_CHARGER_BQ24261)	+= bq24261_charger.o
>  obj-$(CONFIG_CHARGER_BQ24257)	+= bq24257_charger.o
>  obj-$(CONFIG_CHARGER_BQ24735)	+= bq24735-charger.o
>  obj-$(CONFIG_CHARGER_BQ25890)	+= bq25890_charger.o
> diff --git a/drivers/power/bq24261_charger.c b/drivers/power/bq24261_charger.c
> new file mode 100644
> index 0000000..04b5752
> --- /dev/null
> +++ b/drivers/power/bq24261_charger.c
> @@ -0,0 +1,1195 @@
> +/*
> + * bq24261_charger.c - BQ24261 Charger driver
> + *
> + * Copyright (C) 2014 Intel Corporation
> + * Author:	Jenny TC <jenny.tc@...el.com>
> + *		Ramakrishna Pallala <ramakrishna.pallala@...el.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * 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.
> + */
> +
> +#include <linux/version.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/slab.h>
> +#include <linux/device.h>
> +#include <linux/i2c.h>
> +#include <linux/power_supply.h>
> +#include <linux/extcon.h>
> +#include <linux/io.h>
> +#include <linux/sched.h>
> +#include <linux/delay.h>
> +#include <linux/acpi.h>
> +#include <linux/power/bq24261_charger.h>
> +
> +#define DEV_NAME "bq24261-charger"
> +
> +#define EXCEPTION_MONITOR_DELAY		(60 * HZ)
> +#define WDT_RESET_DELAY			(15 * HZ)
> +
> +/* BQ24261 registers */
> +#define BQ24261_STAT_CTRL0_ADDR		0x00
> +#define BQ24261_CTRL_ADDR		0x01
> +#define BQ24261_BATT_VOL_CTRL_ADDR	0x02
> +#define BQ24261_VENDOR_REV_ADDR		0x03
> +#define BQ24261_TERM_FCC_ADDR		0x04
> +#define BQ24261_VINDPM_STAT_ADDR	0x05
> +#define BQ24261_ST_NTC_MON_ADDR		0x06
> +
> +#define BQ24261_RESET_ENABLE		BIT(7)

Similar to the comment made earlier by Andy... Would be good to prefix
each block of register bits with a comment containing the register name.
This way, it'll be easier to understand/maintain the code without having
to need to double-check with the datasheet all the time where which bit
needs to go.

For this to work the register bits would also need to be
organized/grouped by control register which is not always the case right
now (for rexample BQ24261_RESET_ENABLE should be defined further down,
and BQ24261_TMR_RST* should be up there with the first block).

> +
> +#define BQ24261_FAULT_MASK		GENMASK(2, 0)
> +#define BQ24261_VOVP			0x01
> +#define BQ24261_LOW_SUPPLY		0x02
> +#define BQ24261_THERMAL_SHUTDOWN	0x03
> +#define BQ24261_BATT_TEMP_FAULT		0x04
> +#define BQ24261_TIMER_FAULT		0x05
> +#define BQ24261_BATT_OVP		0x06
> +#define BQ24261_NO_BATTERY		0x07
> +#define BQ24261_STAT_MASK		(0x03 << 4)
> +#define BQ24261_STAT_READY		0x00
> +#define BQ24261_STAT_CHRG_PRGRSS	(0x01 << 4)
> +#define BQ24261_STAT_CHRG_DONE		(0x02 << 4)
> +#define BQ24261_STAT_FAULT		(0x03 << 4)
> +#define BQ24261_BOOST_MASK		BIT(6)
> +#define BQ24261_ENABLE_BOOST		BIT(6)
> +#define BQ24261_TMR_RST_MASK		(0x01 << 7)
> +#define BQ24261_TMR_RST			(0x01 << 7)
> +
> +#define BQ24261_CE_MASK			BIT(1)
> +#define BQ24261_CE_DISABLE		BIT(1)
> +
> +#define BQ24261_HiZ_MASK		BIT(0)
> +#define BQ24261_HiZ_ENABLE		BIT(0)

Only use capital letters in #defines...
(https://www.kernel.org/doc/Documentation/CodingStyle chapter 12)

> +
> +#define BQ24261_ICHRG_MASK		GENMASK(7, 3)
> +
> +#define BQ24261_ITERM_MASK		GENMASK(2, 0)
> +#define BQ24261_MIN_ITERM		50 /* 50 mA */
> +#define BQ24261_MAX_ITERM		300 /* 300 mA */
> +
> +#define BQ24261_VBREG_MASK		GENMASK(7, 2)
> +#define BQ24261_VBREG_MIN_CV		3500
> +#define BQ24261_VBREG_MAX_CV		4440
> +#define BQ24261_VBREG_CV_DIV		20
> +#define BQ24261_VBREG_CV_BIT_POS	2
> +
> +#define BQ24261_INLMT_MASK		GENMASK(6, 4)
> +#define BQ24261_INLMT_100		0x00
> +#define BQ24261_INLMT_150		(0x01 << 4)
> +#define BQ24261_INLMT_500		(0x02 << 4)
> +#define BQ24261_INLMT_900		(0x03 << 4)
> +#define BQ24261_INLMT_1500		(0x04 << 4)
> +#define BQ24261_INLMT_2000		(0x05 << 4)
> +#define BQ24261_INLMT_2500		(0x06 << 4)
> +
> +#define BQ24261_TE_MASK			BIT(2)
> +#define BQ24261_TE_ENABLE		BIT(2)
> +#define BQ24261_STAT_ENABLE_MASK	BIT(3)
> +#define BQ24261_STAT_ENABLE		BIT(3)
> +
> +#define BQ24261_VENDOR_MASK		GENMASK(7, 5)
> +#define BQ24261_PART_MASK		GENMASK(4, 3)
> +#define BQ24261_REV_MASK		(0x07)
> +#define VENDOR_BQ2426X			(0x02 << 5)
> +#define REV_BQ24261			(0x06)
> +
> +#define BQ24261_TS_MASK			BIT(3)
> +#define BQ24261_TS_ENABLED		BIT(3)
> +#define BQ24261_BOOST_ILIM_MASK		BIT(4)
> +#define BQ24261_BOOST_ILIM_500ma	(0x0)

Only use capital letters in #defines...

> +#define BQ24261_BOOST_ILIM_1A		BIT(4)
> +#define BQ24261_VINDPM_OFF_MASK		BIT(0)
> +#define BQ24261_VINDPM_OFF_5V		(0x0)
> +#define BQ24261_VINDPM_OFF_12V		BIT(0)
> +
> +#define BQ24261_SAFETY_TIMER_MASK	GENMASK(6, 5)
> +#define BQ24261_SAFETY_TIMER_40MIN	0x00
> +#define BQ24261_SAFETY_TIMER_6HR	(0x01 << 5)
> +#define BQ24261_SAFETY_TIMER_9HR	(0x02 << 5)
> +#define BQ24261_SAFETY_TIMER_DISABLED	(0x03 << 5)
> +
> +/* Settings for Voltage / DPPM Register (05) */
> +#define BQ24261_VBATT_LEVEL1		3700000
> +#define BQ24261_VBATT_LEVEL2		3960000
> +#define BQ24261_VINDPM_MASK		GENMASK(2, 0)
> +#define BQ24261_VINDPM_320MV		(0x01 << 2)
> +#define BQ24261_VINDPM_160MV		(0x01 << 1)
> +#define BQ24261_VINDPM_80MV		(0x01 << 0)
> +#define BQ24261_CD_STATUS_MASK		(0x01 << 3)
> +#define BQ24261_DPM_EN_MASK		(0x01 << 4)
> +#define BQ24261_DPM_EN_FORCE		(0x01 << 4)
> +#define BQ24261_LOW_CHG_MASK		(0x01 << 5)
> +#define BQ24261_LOW_CHG_EN		(0x01 << 5)
> +#define BQ24261_LOW_CHG_DIS		(~BQ24261_LOW_CHG_EN)

Redundant (and confusing) bit-definition? I think for the sake of
consistency we should only define actual device bits in this #define
section...

> +#define BQ24261_DPM_STAT_MASK		(0x01 << 6)
> +#define BQ24261_MINSYS_STAT_MASK	(0x01 << 7)
> +
> +#define BQ24261_MIN_CC			500	/* 500mA */
> +#define BQ24261_MAX_CC			3000	/* 3A */
> +#define BQ24261_DEF_CC			1300	/* 1300mA */
> +#define BQ24261_MAX_CV			4350	/*4350mV */
> +#define BQ24261_DEF_CV			4350	/* 4350mV */
> +#define BQ24261_DEF_ITERM		128	/* 128mA */
> +#define BQ24261_MIN_TEMP		0	/* 0 degC */
> +#define BQ24261_MAX_TEMP		60	/* 60 DegC */
> +
> +#define ILIM_100MA			100	/* 100mA */
> +#define ILIM_500MA			500	/* 500mA */
> +#define ILIM_900MA			900	/* 900mA */
> +#define ILIM_1500MA			1500	/* 1500mA */
> +#define ILIM_2000MA			2000	/* 2000mA */
> +#define ILIM_2500MA			2500	/* 2500mA */
> +#define ILIM_3000MA			3000	/* 3000mA */
> +
> +static unsigned int dis_sysfs_write;
> +module_param(dis_sysfs_write, int, 0644);
> +MODULE_PARM_DESC(dis_sysfs_write,
> +	"Disable sysfs write on charge current and voltage");
> +
> +u16 bq24261_inlmt[][2] = {
> +	{100, BQ24261_INLMT_100},
> +	{150, BQ24261_INLMT_150},
> +	{500, BQ24261_INLMT_500},
> +	{900, BQ24261_INLMT_900},
> +	{1500, BQ24261_INLMT_1500},
> +	{2000, BQ24261_INLMT_2000},
> +	{2500, BQ24261_INLMT_2500},
> +};
> +
> +
> +enum bq24261_status {
> +	BQ24261_CHRGR_STAT_UNKNOWN,
> +	BQ24261_CHRGR_STAT_READY,
> +	BQ24261_CHRGR_STAT_CHARGING,
> +	BQ24261_CHRGR_STAT_FULL,
> +	BQ24261_CHRGR_STAT_FAULT,
> +};
> +
> +enum bq2426x_model {
> +	BQ2426X = 0,
> +	BQ24260,
> +	BQ24261,
> +};

Currently you only support one device... why this effort?

> +
> +struct bq24261_charger {
> +	struct i2c_client *client;
> +	struct bq24261_platform_data *pdata;
> +	struct power_supply *psy_usb;
> +	struct delayed_work fault_mon_work;
> +	struct mutex lock;
> +	enum bq2426x_model model;
> +	struct delayed_work wdt_work;
> +	struct work_struct irq_work;
> +	struct list_head irq_queue;
> +
> +	/* extcon charger cables */
> +	struct {
> +		struct work_struct work;
> +		struct notifier_block nb;
> +		struct extcon_specific_cable_nb sdp;
> +		struct extcon_specific_cable_nb cdp;
> +		struct extcon_specific_cable_nb dcp;
> +		struct extcon_specific_cable_nb otg;
> +		enum power_supply_type chg_type;
> +		bool boost;
> +		bool connected;
> +	} cable;
> +
> +	bool online;
> +	bool present;
> +	int chg_health;
> +	enum bq24261_status chg_status;
> +	int cc;
> +	int cv;
> +	int inlmt;
> +	int max_cc;
> +	int max_cv;
> +	int iterm;
> +	int max_temp;
> +	int min_temp;
> +	bool is_charging_enabled;
> +};
> +
> +static inline int bq24261_read_reg(struct i2c_client *client, u8 reg)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_read_byte_data(client, reg);
> +	if (ret < 0)
> +		dev_err(&client->dev,
> +			"error(%d) in reading reg %d\n", ret, reg);
> +	return ret;
> +}
> +
> +static inline int bq24261_write_reg(struct i2c_client *client, u8 reg, u8 data)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_write_byte_data(client, reg, data);
> +	if (ret < 0)
> +		dev_err(&client->dev,
> +			"error(%d) in writing %d to reg %d\n", ret, data, reg);
> +	return ret;
> +}
> +
> +static inline int bq24261_update_reg(struct i2c_client *client, u8 reg,
> +					  u8 mask, u8 val)
> +{
> +	int ret;
> +
> +	ret = bq24261_read_reg(client, reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = (ret & ~mask) | (mask & val);
> +	return bq24261_write_reg(client, reg, ret);
> +}
> +
> +static void lookup_regval(u16 tbl[][2], size_t size, u16 in_val, u8 *out_val)
> +{
> +	int i;
> +
> +	for (i = 1; i < size; ++i) {
> +		if (in_val < tbl[i][0])
> +			break;
> +	}
> +
> +	*out_val = (u8) tbl[i - 1][1];
> +}
> +
> +void bq24261_cc_to_reg(int cc, u8 *reg_val)
> +{
> +	/*
> +	 * Ichrg bits are B3-B7
> +	 * Icharge = 500mA + IchrgCode * 100mA
> +	 */
> +	cc = clamp_t(int, cc, BQ24261_MIN_CC, BQ24261_MAX_CC);
> +	cc = cc - BQ24261_MIN_CC;
> +	*reg_val = (cc / 100) << 3;
> +}
> +
> +void bq24261_cv_to_reg(int cv, u8 *reg_val)
> +{
> +	int val;
> +
> +	val = clamp_t(int, cv, BQ24261_VBREG_MIN_CV, BQ24261_VBREG_MAX_CV);
> +	*reg_val = (((val - BQ24261_VBREG_MIN_CV) / BQ24261_VBREG_CV_DIV)
> +			<< BQ24261_VBREG_CV_BIT_POS);
> +}
> +
> +void bq24261_inlmt_to_reg(int inlmt, u8 *regval)
> +{
> +	return lookup_regval(bq24261_inlmt, ARRAY_SIZE(bq24261_inlmt),
> +			     inlmt, regval);
> +}
> +
> +static inline void bq24261_iterm_to_reg(int iterm, u8 *regval)
> +{
> +	/*
> +	 * Iterm bits are B0-B2
> +	 * Icharge = 50mA + ItermCode * 50mA
> +	 */
> +	iterm = clamp_t(int, iterm, BQ24261_MIN_ITERM,  BQ24261_MAX_ITERM);
> +	iterm = iterm - BQ24261_MIN_ITERM;
> +	*regval =  iterm / 50;
> +}
> +
> +static inline int bq24261_init_timers(struct bq24261_charger *chip)
> +{
> +	u8 reg_val;
> +	int ret;
> +
> +	reg_val = BQ24261_SAFETY_TIMER_9HR;

Seem awfully long... Do you have a specific use case for this? What
about using 6h? This would also be in line with the related
bq24257_charger.c driver.

> +
> +	if (chip->pdata->thermal_sensing)
> +		reg_val |= BQ24261_TS_ENABLED;
> +
> +	ret = bq24261_update_reg(chip->client, BQ24261_ST_NTC_MON_ADDR,
> +			BQ24261_TS_MASK | BQ24261_SAFETY_TIMER_MASK |
> +			BQ24261_BOOST_ILIM_MASK, reg_val);

This code section overwrites the power-on default current limit for USB
OTG operation from 1A to 500mA. Is this intentionally? Shouldn't we make
this a DT property instead? Since depending on a system's HW one may
want to use either value, and this shouldn't change at runtime.

> +
> +	return ret;
> +}
> +
> +static inline int bq24261_reset_wdt_timer(struct bq24261_charger *chip)
> +{
> +	u8 mask = BQ24261_TMR_RST_MASK, val = BQ24261_TMR_RST;
> +
> +	if (chip->cable.boost) {
> +		mask |= BQ24261_BOOST_MASK;
> +		val |= BQ24261_ENABLE_BOOST;
> +	}
> +
> +	return bq24261_update_reg(chip->client, BQ24261_STAT_CTRL0_ADDR,
> +							mask, val);
> +}
> +
> +static inline int bq24261_set_cc(struct bq24261_charger *chip, int cc_mA)
> +{
> +	u8 reg_val;
> +	int ret;
> +
> +	dev_dbg(&chip->client->dev, "%s=%d\n", __func__, cc_mA);
> +
> +	if (cc_mA && (cc_mA < BQ24261_MIN_CC)) {
> +		dev_dbg(&chip->client->dev, "Set LOW_CHG bit\n");
> +		reg_val = BQ24261_LOW_CHG_EN;
> +		ret = bq24261_update_reg(chip->client,
> +				BQ24261_VINDPM_STAT_ADDR,
> +				BQ24261_LOW_CHG_MASK, reg_val);
> +		return ret;
> +	}
> +
> +	reg_val = BQ24261_LOW_CHG_DIS;
> +	ret = bq24261_update_reg(chip->client, BQ24261_VINDPM_STAT_ADDR,
> +					BQ24261_LOW_CHG_MASK, reg_val);
> +
> +	bq24261_cc_to_reg(cc_mA, &reg_val);
> +
> +	return bq24261_update_reg(chip->client, BQ24261_TERM_FCC_ADDR,
> +			BQ24261_ICHRG_MASK, reg_val);
> +}
> +
> +static inline int bq24261_set_cv(struct bq24261_charger *chip, int cv_mV)
> +{
> +	u8 reg_val;
> +
> +	dev_dbg(&chip->client->dev, "%s=%d\n", __func__, cv_mV);
> +
> +	bq24261_cv_to_reg(cv_mV, &reg_val);
> +
> +	return bq24261_update_reg(chip->client, BQ24261_BATT_VOL_CTRL_ADDR,
> +				       BQ24261_VBREG_MASK, reg_val);
> +}
> +
> +static inline int bq24261_set_inlmt(struct bq24261_charger *chip, int inlmt)
> +{
> +	u8 reg_val;
> +
> +	dev_dbg(&chip->client->dev, "%s=%d\n", __func__, inlmt);
> +
> +	bq24261_inlmt_to_reg(inlmt, &reg_val);
> +
> +	/*
> +	 * Don't enable reset bit. Setting this
> +	 * bit will reset all the registers
> +	 */
> +	reg_val &= ~BQ24261_RESET_ENABLE;
> +
> +	return bq24261_update_reg(chip->client, BQ24261_CTRL_ADDR,
> +		       BQ24261_RESET_ENABLE | BQ24261_INLMT_MASK, reg_val);
> +
> +}
> +
> +static inline int bq24261_set_iterm(struct bq24261_charger *chip, int iterm)
> +{
> +	u8 reg_val;
> +
> +	bq24261_iterm_to_reg(iterm, &reg_val);
> +
> +	return bq24261_update_reg(chip->client, BQ24261_TERM_FCC_ADDR,
> +				       BQ24261_ITERM_MASK, reg_val);
> +}
> +
> +static inline int bq24261_enable_charging(struct bq24261_charger *chip,
> +								bool enable)
> +{
> +	int ret;
> +	u8 reg_val;
> +
> +	if (enable) {
> +		reg_val = (~BQ24261_CE_DISABLE & BQ24261_CE_MASK);
> +		reg_val |= BQ24261_TE_ENABLE;
> +	} else {
> +		reg_val = BQ24261_CE_DISABLE;
> +	}
> +
> +	reg_val |=  BQ24261_STAT_ENABLE;
> +
> +	/*
> +	 * Don't enable reset bit. Setting this
> +	 * bit will reset all the registers
> +	 */
> +	reg_val &= ~BQ24261_RESET_ENABLE;
> +
> +	ret = bq24261_update_reg(chip->client, BQ24261_CTRL_ADDR,
> +		       BQ24261_STAT_ENABLE_MASK | BQ24261_RESET_ENABLE |
> +				BQ24261_CE_MASK | BQ24261_TE_MASK,
> +					reg_val);
> +	if (ret || !enable)
> +		return ret;
> +
> +	/* Set termination current */
> +	ret = bq24261_set_iterm(chip, chip->iterm);
> +	if (ret < 0)
> +		dev_err(&chip->client->dev, "failed to set iTerm(%d)\n", ret);
> +
> +	/* Start WDT and Safety timers */
> +	ret = bq24261_init_timers(chip);
> +	if (ret)
> +		dev_err(&chip->client->dev, "failed to set timers(%d)\n", ret);
> +
> +	return ret;
> +}
> +
> +static inline int bq24261_enable_charger(struct bq24261_charger *chip,
> +								int enable)
> +{
> +	u8 reg_val;
> +	int ret;
> +
> +	reg_val = enable ? (~BQ24261_HiZ_ENABLE & BQ24261_HiZ_MASK) :
> +			BQ24261_HiZ_ENABLE;
> +
> +	/*
> +	 * Don't enable reset bit. Setting this
> +	 * bit will reset all the registers/
> +	 */
> +	reg_val &= ~BQ24261_RESET_ENABLE;
> +
> +	ret = bq24261_update_reg(chip->client, BQ24261_CTRL_ADDR,
> +		       BQ24261_HiZ_MASK | BQ24261_RESET_ENABLE, reg_val);
> +	if (ret)
> +		return ret;
> +
> +	return bq24261_reset_wdt_timer(chip);
> +}
> +
> +static void bq24261_handle_health(struct bq24261_charger *chip, u8 stat_reg)
> +{
> +	struct i2c_client *client = chip->client;
> +	bool fault_worker = false;
> +
> +	switch (stat_reg & BQ24261_FAULT_MASK) {
> +	case BQ24261_VOVP:
> +		chip->chg_health = POWER_SUPPLY_HEALTH_OVERVOLTAGE;
> +		fault_worker = true;
> +		dev_err(&client->dev, "Charger Over Voltage Fault\n");
> +		break;
> +	case BQ24261_LOW_SUPPLY:
> +		chip->chg_health = POWER_SUPPLY_HEALTH_DEAD;
> +		fault_worker = true;
> +		dev_err(&client->dev, "Charger Low Supply Fault\n");
> +		break;

You'll get this fault when no supply is connected. I think in that case
it's a bit of a stretch calling the entire charger device instance
"DEAD". Also see a related thread here...
http://marc.info/?t=144107351700001&r=1&w=2

> +	case BQ24261_THERMAL_SHUTDOWN:
> +		chip->chg_health = POWER_SUPPLY_HEALTH_OVERHEAT;
> +		dev_err(&client->dev, "Charger Thermal Fault\n");
> +		break;
> +	case BQ24261_BATT_TEMP_FAULT:
> +		dev_err(&client->dev, "Battery Temperature Fault\n");
> +		break;
> +	case BQ24261_TIMER_FAULT:
> +		chip->chg_health = POWER_SUPPLY_HEALTH_UNSPEC_FAILURE;
> +		dev_err(&client->dev, "Charger Timer Fault\n");
> +		break;
> +	case BQ24261_BATT_OVP:
> +		chip->chg_health = POWER_SUPPLY_HEALTH_UNSPEC_FAILURE;
> +		dev_err(&client->dev, "Battery Over Voltage Fault\n");
> +		break;
> +	case BQ24261_NO_BATTERY:
> +		dev_err(&client->dev, "No Battery Connected\n");
> +		break;
> +	default:
> +		chip->chg_health = POWER_SUPPLY_HEALTH_GOOD;
> +	}
> +
> +	if (fault_worker)
> +		schedule_delayed_work(&chip->fault_mon_work,
> +					EXCEPTION_MONITOR_DELAY);

How was it decided for which error cases to run fault_mon_work?

> +}
> +
> +static void bq24261_handle_status(struct bq24261_charger *chip, u8 stat_reg)
> +{
> +	struct i2c_client *client = chip->client;
> +
> +	switch (stat_reg & BQ24261_STAT_MASK) {
> +	case BQ24261_STAT_READY:
> +		chip->chg_status = BQ24261_CHRGR_STAT_READY;
> +		dev_info(&client->dev, "Charger Status: Ready\n");
> +		break;
> +	case BQ24261_STAT_CHRG_PRGRSS:
> +		chip->chg_status = BQ24261_CHRGR_STAT_CHARGING;
> +		dev_info(&client->dev, "Charger Status: Charge Progress\n");
> +		break;
> +	case BQ24261_STAT_CHRG_DONE:
> +		chip->chg_status = BQ24261_CHRGR_STAT_FULL;
> +		dev_info(&client->dev, "Charger Status: Charge Done\n");
> +		break;
> +	case BQ24261_STAT_FAULT:
> +		chip->chg_status = BQ24261_CHRGR_STAT_FAULT;
> +		dev_warn(&client->dev, "Charger Status: Fault\n");
> +		break;
> +	default:
> +		dev_info(&client->dev, "Invalid\n");
> +	}

The 'default' branch is redundant. The switch expression can only have
one out of 4 values - all of which are listed through case clauses.

> +}
> +
> +static int bq24261_get_charger_health(struct bq24261_charger *chip)
> +{
> +	if (!chip->present)
> +		return POWER_SUPPLY_HEALTH_UNKNOWN;
> +
> +	return chip->chg_health;
> +}
> +
> +static int bq24261_get_charging_status(struct bq24261_charger *chip)
> +{
> +	int status;
> +
> +	if (!chip->present)
> +		return POWER_SUPPLY_STATUS_DISCHARGING;
> +
> +	switch (chip->chg_status) {
> +	case BQ24261_CHRGR_STAT_READY:
> +		status = POWER_SUPPLY_STATUS_DISCHARGING;
> +		break;
> +	case BQ24261_CHRGR_STAT_CHARGING:
> +		status = POWER_SUPPLY_STATUS_CHARGING;
> +		break;
> +	case BQ24261_CHRGR_STAT_FULL:
> +		status = POWER_SUPPLY_STATUS_FULL;
> +		break;
> +	case BQ24261_CHRGR_STAT_FAULT:
> +		status = POWER_SUPPLY_STATUS_NOT_CHARGING;
> +		break;
> +	default:
> +		status = POWER_SUPPLY_STATUS_DISCHARGING;
> +	}
> +
> +	return status;
> +}
> +
> +static int bq24261_usb_get_property(struct power_supply *psy,
> +		enum power_supply_property psp, union power_supply_propval *val)
> +{
> +	struct bq24261_charger *chip = power_supply_get_drvdata(psy);
> +
> +	mutex_lock(&chip->lock);
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_PRESENT:
> +		val->intval = chip->present;
> +		break;
> +	case POWER_SUPPLY_PROP_ONLINE:
> +		val->intval = chip->online;
> +		break;
> +	case POWER_SUPPLY_PROP_HEALTH:
> +		val->intval = bq24261_get_charger_health(chip);
> +		break;
> +	case POWER_SUPPLY_PROP_STATUS:
> +		val->intval = bq24261_get_charging_status(chip);
> +		break;
> +	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX:
> +		val->intval = chip->pdata->max_cc * 1000;
> +		break;
> +	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE_MAX:
> +		val->intval = chip->pdata->max_cv * 1000;
> +		break;
> +	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT:
> +		val->intval = chip->cc * 1000;

If somebody sets a charge current of <500mA, the driver activates the
LOW_CHG feature. In this case however the chip->cc does not get updated
accordingly, and hence the current reported back through
bq24261_usb_set_property() will be whatever value the user has
programmed rather than 300mA which I think should get reported instead
(the change to be made is not here but rather in bq24261_set_cc()).

> +		break;
> +	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE:
> +		val->intval = chip->cv * 1000;
> +		break;
> +	case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
> +		val->intval = chip->inlmt * 1000;
> +		break;
> +	case POWER_SUPPLY_PROP_CHARGE_TERM_CURRENT:
> +		val->intval = chip->iterm * 1000;
> +		break;
> +	case POWER_SUPPLY_PROP_TEMP_MAX:
> +		val->intval = chip->pdata->max_temp * 10;
> +		break;
> +	case POWER_SUPPLY_PROP_TEMP_MIN:
> +		val->intval = chip->pdata->min_temp * 10;
> +		break;
> +	default:
> +		mutex_unlock(&chip->lock);
> +		return -EINVAL;
> +	}
> +	mutex_unlock(&chip->lock);
> +
> +	return 0;
> +}
> +
> +static int bq24261_usb_set_property(struct power_supply *psy,
> +	enum power_supply_property psp, const union power_supply_propval *val)
> +{
> +	struct bq24261_charger *chip = power_supply_get_drvdata(psy);
> +	int intval, ret = 0;
> +
> +	mutex_lock(&chip->lock);
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT:
> +		/* convert uA to mA */
> +		intval = val->intval / 1000;
> +		if (intval > chip->max_cc) {
> +			ret = -EINVAL;
> +			break;
> +		}
> +
> +		ret = bq24261_set_cc(chip, intval);
> +		if (!ret)
> +			chip->cc = intval;
> +		break;
> +	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE:
> +		/* convert uA to mV */
> +		intval = val->intval / 1000;
> +		if (intval > chip->max_cv) {
> +			ret = -EINVAL;
> +			break;
> +		}
> +
> +		ret = bq24261_set_cv(chip, intval);
> +		if (!ret)
> +			chip->cv = intval;
> +		break;
> +	default:
> +		ret = -EINVAL;
> +	}
> +	mutex_unlock(&chip->lock);
> +
> +	return ret;
> +}
> +
> +static int bq24261_property_is_writeable(struct power_supply *psy,
> +		enum power_supply_property psp)
> +{
> +	int ret;
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT:
> +	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE:
> +		ret = 1;
> +		break;
> +	default:
> +		ret = 0;
> +	}
> +
> +	return ret;
> +}
> +
> +static enum power_supply_property bq24261_usb_props[] = {
> +	POWER_SUPPLY_PROP_PRESENT,
> +	POWER_SUPPLY_PROP_ONLINE,
> +	POWER_SUPPLY_PROP_TYPE,
> +	POWER_SUPPLY_PROP_HEALTH,
> +	POWER_SUPPLY_PROP_STATUS,
> +	POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX,
> +	POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE_MAX,
> +	POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT,
> +	POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE,
> +	POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
> +	POWER_SUPPLY_PROP_CHARGE_TERM_CURRENT,
> +	POWER_SUPPLY_PROP_TEMP_MAX,
> +	POWER_SUPPLY_PROP_TEMP_MIN,
> +};
> +
> +static char *bq24261_charger_supplied_to[] = {
> +	"main-battery",
> +};
> +
> +static struct power_supply_desc bq24261_charger_desc = {
> +	.name			= DEV_NAME,
> +	.type			= POWER_SUPPLY_TYPE_USB,
> +	.properties		= bq24261_usb_props,
> +	.num_properties		= ARRAY_SIZE(bq24261_usb_props),
> +	.get_property		= bq24261_usb_get_property,
> +};
> +
> +static void bq24261_wdt_reset_worker(struct work_struct *work)
> +{
> +
> +	struct bq24261_charger *chip = container_of(work,
> +			    struct bq24261_charger, wdt_work.work);
> +	int ret;
> +
> +	ret = bq24261_reset_wdt_timer(chip);
> +	if (ret)
> +		dev_err(&chip->client->dev, "WDT timer reset error(%d)\n", ret);
> +
> +	schedule_delayed_work(&chip->wdt_work, WDT_RESET_DELAY);
> +}
> +
> +static void bq24261_irq_worker(struct work_struct *work)
> +{
> +	struct bq24261_charger *chip =
> +	    container_of(work, struct bq24261_charger, irq_work);
> +	int ret;
> +
> +	/*
> +	 * Lock to ensure that interrupt register readings are done
> +	 * and processed sequentially. The interrupt Fault registers
> +	 * are read on clear and without sequential processing double
> +	 * fault interrupts or fault recovery cannot be handlled propely
> +	 */
> +
> +	mutex_lock(&chip->lock);
> +
> +	ret = bq24261_read_reg(chip->client, BQ24261_STAT_CTRL0_ADDR);
> +	if (ret < 0) {
> +		dev_err(&chip->client->dev,
> +			"Error (%d) in reading BQ24261_STAT_CTRL0_ADDR\n", ret);
> +		goto irq_out;
> +	}
> +
> +	if (!chip->cable.boost) {
> +		bq24261_handle_status(chip, ret);
> +		bq24261_handle_health(chip, ret);
> +		power_supply_changed(chip->psy_usb);
> +	}
> +
> +irq_out:
> +	mutex_unlock(&chip->lock);
> +}
> +
> +static irqreturn_t bq24261_thread_handler(int id, void *data)
> +{
> +	struct bq24261_charger *chip = (struct bq24261_charger *)data;
> +
> +	queue_work(system_highpri_wq, &chip->irq_work);
> +	return IRQ_HANDLED;
> +}
> +
> +static void bq24261_fault_mon_work(struct work_struct *work)
> +{
> +	struct bq24261_charger *chip = container_of(work,
> +			struct bq24261_charger, fault_mon_work.work);
> +	int ret;
> +
> +	if ((chip->chg_health == POWER_SUPPLY_HEALTH_OVERVOLTAGE) ||
> +		(chip->chg_health == POWER_SUPPLY_HEALTH_DEAD)) {
> +
> +		mutex_lock(&chip->lock);
> +		ret = bq24261_read_reg(chip->client, BQ24261_STAT_CTRL0_ADDR);
> +		if (ret < 0) {
> +			dev_err(&chip->client->dev,
> +				"Status register read failed(%d)\n", ret);
> +			goto fault_mon_out;
> +		}
> +
> +		if ((ret & BQ24261_STAT_MASK) == BQ24261_STAT_READY) {
> +			dev_info(&chip->client->dev,
> +					"Charger fault recovered\n");
> +			bq24261_handle_status(chip, ret);
> +			bq24261_handle_health(chip, ret);
> +			power_supply_changed(chip->psy_usb);
> +		}
> +fault_mon_out:
> +		mutex_unlock(&chip->lock);
> +	}
> +}
> +
> +static void bq24261_boost_control(struct bq24261_charger *chip, bool enable)
> +{
> +	int ret;
> +
> +	if (enable)
> +		ret = bq24261_write_reg(chip->client, BQ24261_STAT_CTRL0_ADDR,
> +				BQ24261_TMR_RST | BQ24261_ENABLE_BOOST);
> +	else
> +		ret = bq24261_write_reg(chip->client,
> +						BQ24261_STAT_CTRL0_ADDR, 0x0);
> +
> +	if (ret < 0)
> +		dev_err(&chip->client->dev,
> +			"stat cntl0 reg access error(%d)\n", ret);
> +}
> +
> +static void bq24261_extcon_event_work(struct work_struct *work)
> +{
> +	struct bq24261_charger *chip =
> +			container_of(work, struct bq24261_charger, cable.work);
> +	int ret, current_limit = 0;
> +	bool old_connected = chip->cable.connected;
> +
> +	/* Determine cable/charger type */
> +	if (extcon_get_cable_state(chip->cable.sdp.edev,
> +					"SLOW-CHARGER") > 0) {
> +		chip->cable.connected = true;
> +		current_limit = ILIM_500MA;
> +		chip->cable.chg_type = POWER_SUPPLY_TYPE_USB;
> +		dev_dbg(&chip->client->dev, "USB SDP charger is connected");
> +	} else if (extcon_get_cable_state(chip->cable.cdp.edev,
> +					"CHARGE-DOWNSTREAM") > 0) {
> +		chip->cable.connected = true;
> +		current_limit = ILIM_1500MA;
> +		chip->cable.chg_type = POWER_SUPPLY_TYPE_USB_CDP;
> +		dev_dbg(&chip->client->dev, "USB CDP charger is connected");
> +	} else if (extcon_get_cable_state(chip->cable.dcp.edev,
> +					"FAST-CHARGER") > 0) {
> +		chip->cable.connected = true;
> +		current_limit = ILIM_1500MA;
> +		chip->cable.chg_type = POWER_SUPPLY_TYPE_USB_DCP;
> +		dev_dbg(&chip->client->dev, "USB DCP charger is connected");
> +	} else if (extcon_get_cable_state(chip->cable.otg.edev,
> +					"USB-Host") > 0) {

"USB-HOST"? See comment further down...

> +		chip->cable.boost = true;
> +		chip->cable.connected = true;
> +		dev_dbg(&chip->client->dev, "USB-Host cable is connected");
> +	} else {
> +		if (old_connected)
> +			dev_dbg(&chip->client->dev, "USB Cable disconnected");
> +		chip->cable.connected = false;
> +		chip->cable.boost = false;
> +		chip->cable.chg_type = POWER_SUPPLY_TYPE_USB;
> +	}
> +
> +	/* Cable status changed */
> +	if (old_connected == chip->cable.connected)
> +		return;
> +
> +	mutex_lock(&chip->lock);
> +	if (chip->cable.connected && !chip->cable.boost) {
> +		chip->inlmt = current_limit;
> +		/* Set up charging */
> +		ret = bq24261_set_cc(chip, chip->cc);
> +		if (ret < 0)
> +			dev_err(&chip->client->dev, "set CC failed(%d)", ret);
> +		ret = bq24261_set_cv(chip, chip->cv);
> +		if (ret < 0)
> +			dev_err(&chip->client->dev, "set CV failed(%d)", ret);
> +		ret = bq24261_set_inlmt(chip, chip->inlmt);
> +		if (ret < 0)
> +			dev_err(&chip->client->dev, "set ILIM failed(%d)", ret);
> +		ret = bq24261_enable_charger(chip, true);
> +		if (ret < 0)
> +			dev_err(&chip->client->dev,
> +					"enable charger failed(%d)", ret);
> +		ret = bq24261_enable_charging(chip, true);
> +		if (ret < 0)
> +			dev_err(&chip->client->dev,
> +					"enable charging failed(%d)", ret);
> +
> +		chip->is_charging_enabled = true;
> +		chip->present = true;
> +		chip->online = true;
> +		schedule_delayed_work(&chip->wdt_work, 0);
> +	} else if (chip->cable.connected && chip->cable.boost) {
> +		/* Enable VBUS for Host Mode */
> +		bq24261_boost_control(chip, true);
> +		schedule_delayed_work(&chip->wdt_work, 0);
> +	} else {
> +		dev_info(&chip->client->dev, "Cable disconnect event\n");
> +		cancel_delayed_work_sync(&chip->wdt_work);
> +		cancel_delayed_work_sync(&chip->fault_mon_work);
> +		bq24261_boost_control(chip, false);
> +		ret = bq24261_enable_charging(chip, false);
> +		if (ret < 0)
> +			dev_err(&chip->client->dev,
> +					"charger disable failed(%d)", ret);
> +
> +		chip->is_charging_enabled = false;
> +		chip->present = false;
> +		chip->online = false;
> +		chip->inlmt = 0;
> +	}
> +	bq24261_charger_desc.type = chip->cable.chg_type;
> +	mutex_unlock(&chip->lock);
> +	power_supply_changed(chip->psy_usb);
> +}
> +
> +static int bq24261_handle_extcon_events(struct notifier_block *nb,
> +				   unsigned long event, void *param)
> +{
> +	struct bq24261_charger *chip =
> +		container_of(nb, struct bq24261_charger, cable.nb);
> +
> +	dev_dbg(&chip->client->dev, "external connector event(%ld)\n", event);
> +
> +	schedule_work(&chip->cable.work);
> +	return NOTIFY_OK;
> +}
> +
> +static int bq24261_extcon_register(struct bq24261_charger *chip)
> +{
> +	int ret;
> +
> +	INIT_WORK(&chip->cable.work, bq24261_extcon_event_work);
> +	chip->cable.nb.notifier_call = bq24261_handle_extcon_events;
> +
> +	ret = extcon_register_interest(&chip->cable.sdp, NULL,
> +				"SLOW-CHARGER", &chip->cable.nb);
> +	if (ret < 0) {
> +		dev_warn(&chip->client->dev,
> +				"extcon SDP registration failed(%d)\n", ret);
> +		goto sdp_reg_failed;
> +	}
> +
> +	ret = extcon_register_interest(&chip->cable.cdp, NULL,
> +				"CHARGE-DOWNSTREAM", &chip->cable.nb);
> +	if (ret < 0) {
> +		dev_warn(&chip->client->dev,
> +				"extcon CDP registration failed(%d)\n", ret);
> +		goto cdp_reg_failed;
> +	}
> +
> +	ret = extcon_register_interest(&chip->cable.dcp, NULL,
> +				"FAST-CHARGER", &chip->cable.nb);
> +	if (ret < 0) {
> +		dev_warn(&chip->client->dev,
> +				"extcon DCP registration failed(%d)\n", ret);
> +		goto dcp_reg_failed;
> +	}
> +
> +	ret = extcon_register_interest(&chip->cable.otg, NULL,
> +				"USB-Host", &chip->cable.nb);

I see this connection name in drivers/extcon/extcon.c being defined as
"USB-HOST". I did not check whether the match will be made
case-sensitive or not but we should keep the exact same capitalization.

> +	if (ret < 0) {
> +		dev_warn(&chip->client->dev,
> +			"extcon USB-Host registration failed(%d)\n", ret);
> +		goto otg_reg_failed;
> +	}
> +
> +	return 0;
> +
> +otg_reg_failed:
> +	extcon_unregister_interest(&chip->cable.dcp);
> +dcp_reg_failed:
> +	extcon_unregister_interest(&chip->cable.cdp);
> +cdp_reg_failed:
> +	extcon_unregister_interest(&chip->cable.sdp);
> +sdp_reg_failed:
> +	return -EPROBE_DEFER;
> +}
> +
> +static void bq24261_of_pdata(struct bq24261_charger *chip)

Might want to remove all the support for platform data. I tried adding
it for bq24257_charger.c but without a solid and immediate use case why
it should be there (which I didn't have) it'll likely get rejected later
on... See applicable discussion here:
http://marc.info/?l=linux-pm&m=144366833328358&w=2

> +{
> +	static struct bq24261_platform_data pdata;
> +	struct device *dev = &chip->client->dev;
> +	int ret, val;
> +
> +	ret = device_property_read_u32(dev,
> +				"ti,charge-current", &val);
> +	if (ret < 0)
> +		goto of_err;
> +	pdata.def_cc = val / 1000;
> +
> +	ret = device_property_read_u32(dev,
> +				"ti,battery-regulation-voltage", &val);
> +	if (ret < 0)
> +		goto of_err;
> +	pdata.def_cv = val / 1000;
> +
> +	ret = device_property_read_u32(dev,
> +				"ti,termination-current", &val);
> +	if (ret < 0)
> +		goto of_err;
> +	pdata.iterm = val / 1000;
> +
> +	/* get optional parameters */
> +	ret = device_property_read_u32(dev,
> +				"ti,max-charge-current", &val);
> +	if (ret < 0)
> +		pdata.max_cc = BQ24261_MAX_CC;
> +	else
> +		pdata.max_cc = val / 1000;
> +
> +	ret = device_property_read_u32(dev,
> +				"ti,max-charge-voltage", &val);
> +	if (ret < 0)
> +		pdata.max_cc = BQ24261_MAX_CV;
> +	else
> +		pdata.max_cv = val / 1000;
> +
> +	ret = device_property_read_u32(dev,
> +				"ti,min-charge-temperature", &val);
> +	if (ret < 0)
> +		pdata.min_temp = BQ24261_MIN_TEMP;
> +	else
> +		pdata.min_temp = val;
> +
> +	ret = device_property_read_u32(dev,
> +				"ti,max-charge-temperature", &val);
> +	if (ret < 0)
> +		pdata.max_temp = BQ24261_MAX_TEMP;
> +	else
> +		pdata.max_temp = val;
> +
> +	ret = device_property_read_u32(dev,
> +				"ti,thermal-sensing", &val);
> +	if (ret < 0)
> +		pdata.thermal_sensing = 0;
> +	else
> +		pdata.thermal_sensing = val;
> +
> +	chip->pdata = &pdata;
> +
> +	return;
> +of_err:
> +	dev_err(dev, "error in getting DT property(%d)\n", ret);
> +}
> +
> +static int bq24261_get_model(struct i2c_client *client,
> +			enum bq2426x_model *model)
> +{
> +	int ret;
> +
> +	ret = bq24261_read_reg(client, BQ24261_VENDOR_REV_ADDR);
> +	if (ret < 0)
> +		return ret;
> +
> +	*model = BQ24261;
> +
> +	return 0;
> +}

As-is this function is redundant since you only support one device right
now. However at a minimum what I'd suggest doing here is checking that
whatever you read out of the device matches the expected datasheet value
- this way giving one layer of checking that the driver is used with the
right device.

> +
> +static int bq24261_probe(struct i2c_client *client,
> +			 const struct i2c_device_id *id)
> +{
> +	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
> +	struct power_supply_config charger_cfg = {};
> +	struct bq24261_charger *chip;
> +	int ret;
> +	enum bq2426x_model model;
> +
> +	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) {
> +		dev_err(&client->dev,
> +			"I2C adapter %s doesn'tsupport BYTE DATA transfer\n",
> +			adapter->name);
> +		return -EIO;
> +	}
> +
> +	ret = bq24261_get_model(client, &model);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "chip detection error (%d)\n", ret);
> +		return -ENODEV;
> +	}
> +

I'd want to use this place here to set the BQ24261_RESET_ENABLE bit
which will reset all register values to their defaults. Reason is this
way there will always be a consistent device state after probe()
independent on what the device was doing or configured for previously
(for example, before the use hit the HW reset button). Less chance for
intermittent failures.

> +	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
> +	if (!chip)
> +		return -ENOMEM;
> +
> +	chip->client = client;
> +	if (client->dev.platform_data)
> +		chip->pdata = client->dev.platform_data;
> +	else if (id->driver_data)
> +		chip->pdata = (struct bq24261_platform_data *)id->driver_data;
> +	else
> +		bq24261_of_pdata(chip);
> +
> +	if (!chip->pdata) {
> +		dev_err(&client->dev, "platform data not found");
> +		return -ENODEV;
> +	}
> +
> +	i2c_set_clientdata(client, chip);
> +	mutex_init(&chip->lock);
> +	chip->model = model;
> +
> +	/* Initialize charger parameters */
> +	chip->cc = chip->pdata->def_cc;
> +	chip->cv = chip->pdata->def_cv;
> +	chip->iterm = chip->pdata->iterm;
> +	chip->chg_status = BQ24261_CHRGR_STAT_UNKNOWN;
> +	chip->chg_health = POWER_SUPPLY_HEALTH_UNKNOWN;
> +
> +	charger_cfg.drv_data = chip;
> +	charger_cfg.supplied_to = bq24261_charger_supplied_to;
> +	charger_cfg.num_supplicants = ARRAY_SIZE(bq24261_charger_supplied_to);
> +	if (!dis_sysfs_write) {
> +		bq24261_charger_desc.set_property = bq24261_usb_set_property;
> +		bq24261_charger_desc.property_is_writeable =
> +						bq24261_property_is_writeable;
> +	}
> +	chip->psy_usb = power_supply_register(&client->dev,
> +				&bq24261_charger_desc, &charger_cfg);
> +	if (IS_ERR(chip->psy_usb)) {
> +		dev_err(&client->dev, "power supply registration failed(%d)\n",
> +							IS_ERR(chip->psy_usb));
> +		return IS_ERR(chip->psy_usb);
> +	}
> +
> +	INIT_DELAYED_WORK(&chip->wdt_work, bq24261_wdt_reset_worker);
> +	INIT_DELAYED_WORK(&chip->fault_mon_work, bq24261_fault_mon_work);
> +
> +	ret = bq24261_extcon_register(chip);

Interesting approach of using extcon to detect the charger type... I had
not seen that. How do you test it? I want to make sure when I run/test
the code I can re-create the different scenarios.

> +	if (ret < 0)
> +		goto extcon_reg_failed;
> +
> +	if (chip->client->irq) {
> +		ret = devm_request_threaded_irq(&client->dev, chip->client->irq,
> +					NULL, bq24261_thread_handler,
> +					IRQF_SHARED | IRQF_NO_SUSPEND,
> +					DEV_NAME, chip);
> +		if (ret) {
> +			dev_err(&client->dev,
> +				"irq request failed (%d)\n", ret);
> +			goto irq_reg_failed;
> +		}
> +		INIT_WORK(&chip->irq_work, bq24261_irq_worker);
> +	}
> +
> +	/* Check for charger connected boot case */
> +	schedule_work(&chip->cable.work);
> +
> +	return 0;
> +
> +irq_reg_failed:
> +	extcon_unregister_interest(&chip->cable.sdp);
> +	extcon_unregister_interest(&chip->cable.cdp);
> +	extcon_unregister_interest(&chip->cable.dcp);
> +	extcon_unregister_interest(&chip->cable.otg);
> +extcon_reg_failed:
> +	power_supply_unregister(chip->psy_usb);
> +	return ret;
> +}
> +
> +static int bq24261_remove(struct i2c_client *client)
> +{
> +	struct bq24261_charger *chip = i2c_get_clientdata(client);
> +
> +	flush_scheduled_work();
> +	extcon_unregister_interest(&chip->cable.sdp);
> +	extcon_unregister_interest(&chip->cable.cdp);
> +	extcon_unregister_interest(&chip->cable.dcp);
> +	extcon_unregister_interest(&chip->cable.otg);
> +	power_supply_unregister(chip->psy_usb);
> +	return 0;
> +}
> +
> +static const struct i2c_device_id bq24261_id[] = {
> +	{"bq24261", 0},

Nitpick. I did not see it in the coding style guide but doing a quick
survey on existing Kernel code shows that for struct declaration it
seems preferred to insert spaces after/before the opening/closing
braces.

> +	{ },
> +};
> +MODULE_DEVICE_TABLE(i2c, bq24261_id);
> +
> +static const struct acpi_device_id bq24261_acpi_match[] = {
> +	{"TBQ24261", 0},

Ditto.

Also, why the 'T' prefix? Can we keep it consistent with what was done
for the bq24257_charger.c driver (adding a trailing 0, that is).

> +	{},

Ditto.

> +};
> +MODULE_DEVICE_TABLE(acpi, bq24261_acpi_match);
> +
> +static const struct of_device_id bq24261_of_match[] = {
> +	{ .compatible = "ti,bq24261", },
> +	{ },

See earlier comment. This is what I mean seems to be the preferred way.

Thanks and Regards,

--
Andreas Dannenberg
Texas Instruments Inc

> +};
> +MODULE_DEVICE_TABLE(of, bq24261_of_match);
> +
> +static struct i2c_driver bq24261_driver = {
> +	.driver = {
> +		.name = DEV_NAME,
> +		.acpi_match_table = ACPI_PTR(bq24261_acpi_match),
> +		.of_match_table = of_match_ptr(bq24261_of_match),
> +	},
> +	.probe = bq24261_probe,
> +	.remove = bq24261_remove,
> +	.id_table = bq24261_id,
> +};
> +
> +module_i2c_driver(bq24261_driver);
> +
> +MODULE_AUTHOR("Jenny TC <jenny.tc@...el.com>");
> +MODULE_AUTHOR("Ramakrishna Pallala <ramakrishna.pallala@...el.com>");
> +MODULE_DESCRIPTION("BQ24261 Charger Driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/power/bq24261_charger.h b/include/linux/power/bq24261_charger.h
> new file mode 100644
> index 0000000..6c7d96e
> --- /dev/null
> +++ b/include/linux/power/bq24261_charger.h
> @@ -0,0 +1,26 @@
> +/*
> + * bq24261_charger.h: platform data structure for bq24261 driver
> + *
> + * Copyright (C) 2014 Intel Corporation
> + *
> + * 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; version 2
> + * of the License.
> + */
> +
> +#ifndef __BQ24261_CHARGER_H__
> +#define __BQ24261_CHARGER_H__
> +
> +struct bq24261_platform_data {
> +	int def_cc;	/* in mA */
> +	int def_cv;	/* in mV */
> +	int iterm;	/* in mA */
> +	int max_cc;	/* in mA */
> +	int max_cv;	/* in mV */
> +	int min_temp;	/* in DegC */
> +	int max_temp;	/* in DegC */
> +	int thermal_sensing;
> +};
> +
> +#endif
> -- 
> 1.7.9.5
> 
--
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