[v13,3/3] usb: typec: maxim_contaminant: Implement check_contaminant callback

  Maxim TCPC has additional ADCs and low current(1ua) current source
to measure the impedance of CC and SBU pins. When tcpm invokes
the check_contaminant callback, Maxim TCPC measures the impedance
of the CC & SBU pins and when the impedance measured is less than
1MOhm, it is assumed that USB-C port is contaminated. CC comparators
are also checked to differentiate between presence of sink and
contaminant. Once USB-C is deemed to be contaminated, MAXIM TCPC
has additional hardware to disable normal DRP toggling cycle and
enable 1ua on CC pins once every 2.4secs/4.8secs. Maxim TCPC
interrupts AP once the impedance on the CC pin is above the
1MOhm threshold. The Maxim tcpc driver then signals TCPM_PORT_CLEAN
to restart toggling.

Renaming tcpci_maxim.c to tcpci_maxim_core.c and moving reg read/write
helper functions to the tcpci_maxim.h header file.

Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
---
Changes since v12:
* Fixed dev_err message.
Changes since v11:
* Fixed missing error handling.
Changes since v10:
* none
Changes since v9:
* None.
Changes since V7:
* None. Skipped versions by mistake.
Changes since v6:
* Refactored logic for check_contaminant and removed
* is_potential_contaminant.
Changes since v5:
* None
Changes since v4:
* Missed committing local changes to fix ktest robot warnings.
  Updated the patch in v5.
Changes since v3:
* Renamed functions and removed the unecessary EXPORT.
* Fixed ktest robot warning.
Changes since v2:
* Implemented is_potential_contaminant to offload
* disconnect_while_debouncing
Changes since v1:
* Renamed tcpci_maxim.c to tcpci_maxim_core.c and compiling
  tcpci_maxim_core.o with maxim_contaminant.o as a single module
  as suggested by Guenter Roeck
* Got rid of exporting symbols for reg read/write helper functions
  and moved them to header as suggested by Heikki Krogerus
* Sqashed the commit which exposed the max_tcpci_read helper functions
  into this one.
---
 drivers/usb/typec/tcpm/Makefile               |   1 +
 drivers/usb/typec/tcpm/maxim_contaminant.c    | 387 ++++++++++++++++++
 drivers/usb/typec/tcpm/tcpci_maxim.h          |  89 ++++
 .../{tcpci_maxim.c => tcpci_maxim_core.c}     |  53 +--
 4 files changed, 498 insertions(+), 32 deletions(-)
 create mode 100644 drivers/usb/typec/tcpm/maxim_contaminant.c
 create mode 100644 drivers/usb/typec/tcpm/tcpci_maxim.h
 rename drivers/usb/typec/tcpm/{tcpci_maxim.c => tcpci_maxim_core.c} (93%)
  

On 1/14/23 01:32, Badhri Jagan Sridharan wrote:
> Maxim TCPC has additional ADCs and low current(1ua) current source
> to measure the impedance of CC and SBU pins. When tcpm invokes
> the check_contaminant callback, Maxim TCPC measures the impedance
> of the CC & SBU pins and when the impedance measured is less than
> 1MOhm, it is assumed that USB-C port is contaminated. CC comparators
> are also checked to differentiate between presence of sink and
> contaminant. Once USB-C is deemed to be contaminated, MAXIM TCPC
> has additional hardware to disable normal DRP toggling cycle and
> enable 1ua on CC pins once every 2.4secs/4.8secs. Maxim TCPC
> interrupts AP once the impedance on the CC pin is above the
> 1MOhm threshold. The Maxim tcpc driver then signals TCPM_PORT_CLEAN
> to restart toggling.
> 
> Renaming tcpci_maxim.c to tcpci_maxim_core.c and moving reg read/write
> helper functions to the tcpci_maxim.h header file.
> 
> Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>

Couple of nits, otherwise

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

Note that this onlyt refers to the syntax and semantics of the code,
not to its functionality. There is too much magic in there for a functional
review.

Thanks,
Guenter

> ---
> Changes since v12:
> * Fixed dev_err message.
> Changes since v11:
> * Fixed missing error handling.
> Changes since v10:
> * none
> Changes since v9:
> * None.
> Changes since V7:
> * None. Skipped versions by mistake.
> Changes since v6:
> * Refactored logic for check_contaminant and removed
> * is_potential_contaminant.
> Changes since v5:
> * None
> Changes since v4:
> * Missed committing local changes to fix ktest robot warnings.
>    Updated the patch in v5.
> Changes since v3:
> * Renamed functions and removed the unecessary EXPORT.
> * Fixed ktest robot warning.
> Changes since v2:
> * Implemented is_potential_contaminant to offload
> * disconnect_while_debouncing
> Changes since v1:
> * Renamed tcpci_maxim.c to tcpci_maxim_core.c and compiling
>    tcpci_maxim_core.o with maxim_contaminant.o as a single module
>    as suggested by Guenter Roeck
> * Got rid of exporting symbols for reg read/write helper functions
>    and moved them to header as suggested by Heikki Krogerus
> * Sqashed the commit which exposed the max_tcpci_read helper functions
>    into this one.
> ---
>   drivers/usb/typec/tcpm/Makefile               |   1 +
>   drivers/usb/typec/tcpm/maxim_contaminant.c    | 387 ++++++++++++++++++
>   drivers/usb/typec/tcpm/tcpci_maxim.h          |  89 ++++
>   .../{tcpci_maxim.c => tcpci_maxim_core.c}     |  53 +--
>   4 files changed, 498 insertions(+), 32 deletions(-)
>   create mode 100644 drivers/usb/typec/tcpm/maxim_contaminant.c
>   create mode 100644 drivers/usb/typec/tcpm/tcpci_maxim.h
>   rename drivers/usb/typec/tcpm/{tcpci_maxim.c => tcpci_maxim_core.c} (93%)
> 
> diff --git a/drivers/usb/typec/tcpm/Makefile b/drivers/usb/typec/tcpm/Makefile
> index 906d9dced8e7..08e57bb499cb 100644
> --- a/drivers/usb/typec/tcpm/Makefile
> +++ b/drivers/usb/typec/tcpm/Makefile
> @@ -8,3 +8,4 @@ obj-$(CONFIG_TYPEC_RT1711H)		+= tcpci_rt1711h.o
>   obj-$(CONFIG_TYPEC_MT6360)		+= tcpci_mt6360.o
>   obj-$(CONFIG_TYPEC_TCPCI_MT6370)	+= tcpci_mt6370.o
>   obj-$(CONFIG_TYPEC_TCPCI_MAXIM)		+= tcpci_maxim.o
> +tcpci_maxim-y				+= tcpci_maxim_core.o maxim_contaminant.o
> diff --git a/drivers/usb/typec/tcpm/maxim_contaminant.c b/drivers/usb/typec/tcpm/maxim_contaminant.c
> new file mode 100644
> index 000000000000..f8504a90da26
> --- /dev/null
> +++ b/drivers/usb/typec/tcpm/maxim_contaminant.c
> @@ -0,0 +1,387 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright 2022 Google, Inc
> + *
> + * USB-C module to reduce wakeups due to contaminants.
> + */
> +
> +#include <linux/device.h>
> +#include <linux/irqreturn.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/usb/tcpci.h>
> +#include <linux/usb/tcpm.h>
> +#include <linux/usb/typec.h>
> +
> +#include "tcpci_maxim.h"
> +
> +enum fladc_select {
> +	CC1_SCALE1 = 1,
> +	CC1_SCALE2,
> +	CC2_SCALE1,
> +	CC2_SCALE2,
> +	SBU1,
> +	SBU2,
> +};
> +
> +#define FLADC_1uA_LSB_MV		25
> +/* High range CC */
> +#define FLADC_CC_HIGH_RANGE_LSB_MV	208
> +/* Low range CC */
> +#define FLADC_CC_LOW_RANGE_LSB_MV      126
> +
> +/* 1uA current source */
> +#define FLADC_CC_SCALE1			1
> +/* 5 uA current source */
> +#define FLADC_CC_SCALE2			5
> +
> +#define FLADC_1uA_CC_OFFSET_MV		300
> +#define FLADC_CC_HIGH_RANGE_OFFSET_MV	624
> +#define FLADC_CC_LOW_RANGE_OFFSET_MV	378
> +
> +#define CONTAMINANT_THRESHOLD_SBU_K	1000
> +#define	CONTAMINANT_THRESHOLD_CC_K	1000
> +
> +#define READ1_SLEEP_MS			10
> +#define READ2_SLEEP_MS			5
> +
> +#define STATUS_CHECK(reg, mask, val)	(((reg) & (mask)) == (val))
> +
> +#define IS_CC_OPEN(cc_status) \
> +	(STATUS_CHECK((cc_status), TCPC_CC_STATUS_CC1_MASK << TCPC_CC_STATUS_CC1_SHIFT,  \
> +		      TCPC_CC_STATE_SRC_OPEN) && STATUS_CHECK((cc_status),               \
> +							      TCPC_CC_STATUS_CC2_MASK << \
> +							      TCPC_CC_STATUS_CC2_SHIFT,  \
> +							      TCPC_CC_STATE_SRC_OPEN))
> +
> +static int max_contaminant_adc_to_mv(struct max_tcpci_chip *chip, enum fladc_select channel,
> +				     bool ua_src, u8 fladc)
> +{
> +	/* SBU channels only have 1 scale with 1uA. */
> +	if ((ua_src && (channel == CC1_SCALE2 || channel == CC2_SCALE2 || channel == SBU1 ||
> +			channel == SBU2)))
> +		/* Mean of range */
> +		return FLADC_1uA_CC_OFFSET_MV + (fladc * FLADC_1uA_LSB_MV);
> +	else if (!ua_src && (channel == CC1_SCALE1 || channel == CC2_SCALE1))
> +		return FLADC_CC_HIGH_RANGE_OFFSET_MV + (fladc * FLADC_CC_HIGH_RANGE_LSB_MV);
> +	else if (!ua_src && (channel == CC1_SCALE2 || channel == CC2_SCALE2))
> +		return FLADC_CC_LOW_RANGE_OFFSET_MV + (fladc * FLADC_CC_LOW_RANGE_LSB_MV);
> +
> +	dev_err_once(chip->dev, "ADC ERROR: SCALE UNKNOWN");
> +
> +	return -EINVAL;
> +}
> +
> +static int max_contaminant_read_adc_mv(struct max_tcpci_chip *chip, enum fladc_select channel,
> +				       int sleep_msec, bool raw, bool ua_src)
> +{
> +	struct regmap *regmap = chip->data.regmap;
> +	u8 fladc;
> +	int ret;
> +
> +	/* Channel & scale select */
> +	ret = regmap_update_bits(regmap, TCPC_VENDOR_ADC_CTRL1, ADCINSEL_MASK,
> +				 channel << ADC_CHANNEL_OFFSET);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Enable ADC */
> +	ret = regmap_update_bits(regmap, TCPC_VENDOR_ADC_CTRL1, ADCEN, ADCEN);
> +	if (ret < 0)
> +		return ret;
> +
> +	usleep_range(sleep_msec * 1000, (sleep_msec + 1) * 1000);
> +	ret = max_tcpci_read8(chip, TCPC_VENDOR_FLADC_STATUS, &fladc);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Disable ADC */
> +	ret = regmap_update_bits(regmap, TCPC_VENDOR_ADC_CTRL1, ADCEN, 0);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_update_bits(regmap, TCPC_VENDOR_ADC_CTRL1, ADCINSEL_MASK, 0);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (!raw)
> +		return max_contaminant_adc_to_mv(chip, channel, ua_src, fladc);
> +	else
> +		return fladc;

else after return is unnecessary. Some static analyzers complain about that,
so you may want to fix it.


> +}
> +
> +static int max_contaminant_read_resistance_kohm(struct max_tcpci_chip *chip,
> +						enum fladc_select channel, int sleep_msec, bool raw)
> +{
> +	struct regmap *regmap = chip->data.regmap;
> +	int mv;
> +	int ret;
> +
> +	if (channel == CC1_SCALE1 || channel == CC2_SCALE1 || channel == CC1_SCALE2 ||
> +	    channel == CC2_SCALE2) {
> +		/* Enable 1uA current source */
> +		ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL2, CCLPMODESEL_MASK,
> +					 ULTRA_LOW_POWER_MODE);
> +		if (ret < 0)
> +			return ret;
> +
> +		/* Enable 1uA current source */
> +		ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL2, CCRPCTRL_MASK, UA_1_SRC);
> +		if (ret < 0)
> +			return ret;
> +
> +		/* OVP disable */
> +		ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL2, CCOVPDIS, CCOVPDIS);
> +		if (ret < 0)
> +			return ret;
> +
> +		mv = max_contaminant_read_adc_mv(chip, channel, sleep_msec, raw, true);
> +		if (mv < 0)
> +			return ret;
> +
> +		/* OVP enable */
> +		ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL2, CCOVPDIS, 0);
> +		if (ret < 0)
> +			return ret;
> +		/* returns KOhm as 1uA source is used. */
> +		return mv;
> +	}
> +
> +	ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL2, SBUOVPDIS, SBUOVPDIS);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* SBU switches auto configure when channel is selected. */
> +	/* Enable 1ua current source */
> +	ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL2, SBURPCTRL, SBURPCTRL);
> +	if (ret < 0)
> +		return ret;
> +
> +	mv = max_contaminant_read_adc_mv(chip, channel, sleep_msec, raw, true);
> +	if (mv < 0)
> +		return ret;
> +	/* Disable current source */
> +	ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL2, SBURPCTRL, 0);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* OVP disable */
> +	ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL2, SBUOVPDIS, 0);
> +	if (ret < 0)
> +		return ret;
> +
> +	return mv;
> +}
> +
> +static int max_contaminant_read_comparators(struct max_tcpci_chip *chip, u8 *vendor_cc_status2_cc1,
> +					    u8 *vendor_cc_status2_cc2)
> +{
> +	struct regmap *regmap = chip->data.regmap;
> +	int ret;
> +
> +	/* Enable 80uA source */
> +	ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL2, CCRPCTRL_MASK, UA_80_SRC);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Enable comparators */
> +	ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL1, CCCOMPEN, CCCOMPEN);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Sleep to allow comparators settle */
> +	usleep_range(5000, 6000);
> +	ret = regmap_update_bits(regmap, TCPC_TCPC_CTRL, TCPC_TCPC_CTRL_ORIENTATION, PLUG_ORNT_CC1);
> +	if (ret < 0)
> +		return ret;
> +
> +	usleep_range(5000, 6000);
> +	ret = max_tcpci_read8(chip, VENDOR_CC_STATUS2, vendor_cc_status2_cc1);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_update_bits(regmap, TCPC_TCPC_CTRL, TCPC_TCPC_CTRL_ORIENTATION, PLUG_ORNT_CC2);
> +	if (ret < 0)
> +		return ret;
> +
> +	usleep_range(5000, 6000);
> +	ret = max_tcpci_read8(chip, VENDOR_CC_STATUS2, vendor_cc_status2_cc2);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL1, CCCOMPEN, 0);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL2, CCRPCTRL_MASK, 0);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int max_contaminant_detect_contaminant(struct max_tcpci_chip *chip)
> +{
> +	int cc1_k, cc2_k, sbu1_k, sbu2_k, ret;
> +	u8 vendor_cc_status2_cc1 = 0xff, vendor_cc_status2_cc2 = 0xff;
> +	u8 role_ctrl = 0, role_ctrl_backup = 0;
> +	int inferred_state = NOT_DETECTED;
> +
> +	ret = max_tcpci_read8(chip, TCPC_ROLE_CTRL, &role_ctrl);
> +	if (ret < 0)
> +		return NOT_DETECTED;
> +
> +	role_ctrl_backup = role_ctrl;
> +	role_ctrl = 0x0F;
> +	ret = max_tcpci_write8(chip, TCPC_ROLE_CTRL, role_ctrl);
> +	if (ret < 0)
> +		return NOT_DETECTED;
> +
> +	cc1_k = max_contaminant_read_resistance_kohm(chip, CC1_SCALE2, READ1_SLEEP_MS, false);
> +	if (cc1_k < 0)
> +		goto exit;
> +
> +	cc2_k = max_contaminant_read_resistance_kohm(chip, CC2_SCALE2, READ2_SLEEP_MS, false);
> +	if (cc2_k < 0)
> +		goto exit;
> +
> +	sbu1_k = max_contaminant_read_resistance_kohm(chip, SBU1, READ1_SLEEP_MS, false);
> +	if (sbu1_k < 0)
> +		goto exit;
> +
> +	sbu2_k = max_contaminant_read_resistance_kohm(chip, SBU2, READ2_SLEEP_MS, false);
> +	if (sbu2_k < 0)
> +		goto exit;
> +
> +	ret = max_contaminant_read_comparators(chip, &vendor_cc_status2_cc1,
> +					       &vendor_cc_status2_cc2);
> +
> +	if (ret < 0)
> +		goto exit;
> +
> +	if ((!(CC1_VUFP_RD0P5 & vendor_cc_status2_cc1) ||
> +	     !(CC2_VUFP_RD0P5 & vendor_cc_status2_cc2)) &&
> +	    !(CC1_VUFP_RD0P5 & vendor_cc_status2_cc1 && CC2_VUFP_RD0P5 & vendor_cc_status2_cc2))
> +		inferred_state = SINK;
> +	else if ((cc1_k < CONTAMINANT_THRESHOLD_CC_K || cc2_k < CONTAMINANT_THRESHOLD_CC_K) &&
> +		 (sbu1_k < CONTAMINANT_THRESHOLD_SBU_K || sbu2_k < CONTAMINANT_THRESHOLD_SBU_K))
> +		inferred_state = DETECTED;
> +
> +	if (inferred_state == NOT_DETECTED)
> +		max_tcpci_write8(chip, TCPC_ROLE_CTRL, role_ctrl_backup);
> +	else
> +		max_tcpci_write8(chip, TCPC_ROLE_CTRL, (TCPC_ROLE_CTRL_DRP | 0xA));
> +
> +	return inferred_state;
> +exit:
> +	max_tcpci_write8(chip, TCPC_ROLE_CTRL, role_ctrl_backup);
> +	return NOT_DETECTED;
> +}
> +
> +static int max_contaminant_enable_dry_detection(struct max_tcpci_chip *chip)
> +{
> +	struct regmap *regmap = chip->data.regmap;
> +	u8 temp;
> +	int ret;
> +
> +	ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL3, CCWTRDEB_MASK | CCWTRSEL_MASK
> +				    | WTRCYCLE_MASK, CCWTRDEB_1MS << CCWTRDEB_SHIFT |
> +				    CCWTRSEL_1V << CCWTRSEL_SHIFT | WTRCYCLE_4_8_S <<
> +				    WTRCYCLE_SHIFT);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_update_bits(regmap, TCPC_ROLE_CTRL, TCPC_ROLE_CTRL_DRP, TCPC_ROLE_CTRL_DRP);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL1, CCCONNDRY, CCCONNDRY);
> +	if (ret < 0)
> +		return ret;
> +	ret = max_tcpci_read8(chip, TCPC_VENDOR_CC_CTRL1, &temp);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_update_bits(regmap, TCPC_VENDOR_CC_CTRL2, CCLPMODESEL_MASK,
> +				 ULTRA_LOW_POWER_MODE);
> +	if (ret < 0)
> +		return ret;
> +	ret = max_tcpci_read8(chip, TCPC_VENDOR_CC_CTRL2, &temp);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Enable Look4Connection before sending the command */
> +	ret = regmap_update_bits(regmap, TCPC_TCPC_CTRL, TCPC_TCPC_CTRL_EN_LK4CONN_ALRT,
> +				 TCPC_TCPC_CTRL_EN_LK4CONN_ALRT);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = max_tcpci_write8(chip, TCPC_COMMAND, TCPC_CMD_LOOK4CONNECTION);
> +	if (ret < 0)
> +		return ret;
> +	return 0;
> +}
> +
> +bool max_contaminant_is_contaminant(struct max_tcpci_chip *chip, bool disconnect_while_debounce)
> +{
> +	u8 cc_status, pwr_cntl;
> +	int ret;
> +
> +	ret = max_tcpci_read8(chip, TCPC_CC_STATUS, &cc_status);
> +	if (ret < 0)
> +		return false;
> +
> +	ret = max_tcpci_read8(chip, TCPC_POWER_CTRL, &pwr_cntl);
> +	if (ret < 0)
> +		return false;
> +
> +	if (chip->contaminant_state == NOT_DETECTED || chip->contaminant_state == SINK) {
> +		if (!disconnect_while_debounce)
> +			msleep(100);
> +
> +		ret = max_tcpci_read8(chip, TCPC_CC_STATUS, &cc_status);
> +		if (ret < 0)
> +			return false;
> +
> +		if (IS_CC_OPEN(cc_status)) {
> +			u8 role_ctrl, role_ctrl_backup;
> +
> +			ret = max_tcpci_read8(chip, TCPC_ROLE_CTRL, &role_ctrl);
> +			if (ret < 0)
> +				return false;
> +
> +			role_ctrl_backup = role_ctrl;
> +			role_ctrl |= 0x0F;
> +			role_ctrl &= ~(TCPC_ROLE_CTRL_DRP);
> +			ret = max_tcpci_write8(chip, TCPC_ROLE_CTRL, role_ctrl);
> +			if (ret < 0)
> +				return false;
> +
> +			chip->contaminant_state = max_contaminant_detect_contaminant(chip);
> +
> +			ret = max_tcpci_write8(chip, TCPC_ROLE_CTRL, role_ctrl_backup);
> +			if (ret < 0)
> +				return false;
> +
> +			if (chip->contaminant_state == DETECTED) {
> +				max_contaminant_enable_dry_detection(chip);
> +				return true;
> +			}
> +		}
> +		return false;
> +	} else if (chip->contaminant_state == DETECTED) {
> +		if (STATUS_CHECK(cc_status, TCPC_CC_STATUS_TOGGLING, 0)) {
> +			chip->contaminant_state = max_contaminant_detect_contaminant(chip);
> +			if (chip->contaminant_state == DETECTED) {
> +				max_contaminant_enable_dry_detection(chip);
> +				return true;
> +			}
> +		}
> +	}
> +
> +	return false;
> +}
> +
> +MODULE_DESCRIPTION("MAXIM TCPC CONTAMINANT Module");
> +MODULE_AUTHOR("Badhri Jagan Sridharan <badhri@google.com>");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/usb/typec/tcpm/tcpci_maxim.h b/drivers/usb/typec/tcpm/tcpci_maxim.h
> new file mode 100644
> index 000000000000..2c1c4d161b0d
> --- /dev/null
> +++ b/drivers/usb/typec/tcpm/tcpci_maxim.h
> @@ -0,0 +1,89 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * Copyright 2022 Google, Inc
> + *
> + * MAXIM TCPC header file.
> + */
> +#ifndef TCPCI_MAXIM_H_
> +#define TCPCI_MAXIM_H_
> +
> +#define VENDOR_CC_STATUS2                       0x85
> +#define CC1_VUFP_RD0P5                          BIT(1)
> +#define CC2_VUFP_RD0P5                          BIT(5)
> +#define TCPC_VENDOR_FLADC_STATUS                0x89
> +
> +#define TCPC_VENDOR_CC_CTRL1                    0x8c
> +#define CCCONNDRY                               BIT(7)
> +#define CCCOMPEN                                BIT(5)
> +
> +#define TCPC_VENDOR_CC_CTRL2                    0x8d
> +#define SBUOVPDIS                               BIT(7)
> +#define CCOVPDIS                                BIT(6)
> +#define SBURPCTRL                               BIT(5)
> +#define CCLPMODESEL_MASK                        GENMASK(4, 3)
> +#define ULTRA_LOW_POWER_MODE                    BIT(3)
> +#define CCRPCTRL_MASK                           GENMASK(2, 0)
> +#define UA_1_SRC                                1
> +#define UA_80_SRC                               3
> +
> +#define TCPC_VENDOR_CC_CTRL3                    0x8e
> +#define CCWTRDEB_MASK                           GENMASK(7, 6)
> +#define CCWTRDEB_SHIFT                          6
> +#define CCWTRDEB_1MS                            1
> +#define CCWTRSEL_MASK                           GENMASK(5, 3)
> +#define CCWTRSEL_SHIFT                          3
> +#define CCWTRSEL_1V                             0x4
> +#define CCLADDERDIS                             BIT(2)
> +#define WTRCYCLE_MASK                           BIT(0)
> +#define WTRCYCLE_SHIFT                          0
> +#define WTRCYCLE_2_4_S                          0
> +#define WTRCYCLE_4_8_S                          1
> +
> +#define TCPC_VENDOR_ADC_CTRL1                   0x91
> +#define ADCINSEL_MASK                           GENMASK(7, 5)
> +#define ADC_CHANNEL_OFFSET                      5
> +#define ADCEN                                   BIT(0)
> +
> +enum contamiant_state {
> +	NOT_DETECTED,
> +	DETECTED,
> +	SINK,
> +};
> +
> +/*
> + * @potential_contaminant:
> + *		Last returned result to tcpm indicating whether the TCPM port
> + *		has potential contaminant.

I don't immediately see what this refers to.

> + */
> +struct max_tcpci_chip {
> +	struct tcpci_data data;
> +	struct tcpci *tcpci;
> +	struct device *dev;
> +	struct i2c_client *client;
> +	struct tcpm_port *port;
> +	enum contamiant_state contaminant_state;
> +};
> +
> +static inline int max_tcpci_read16(struct max_tcpci_chip *chip, unsigned int reg, u16 *val)
> +{
> +	return regmap_raw_read(chip->data.regmap, reg, val, sizeof(u16));
> +}
> +
> +static inline int max_tcpci_write16(struct max_tcpci_chip *chip, unsigned int reg, u16 val)
> +{
> +	return regmap_raw_write(chip->data.regmap, reg, &val, sizeof(u16));
> +}
> +
> +static inline int max_tcpci_read8(struct max_tcpci_chip *chip, unsigned int reg, u8 *val)
> +{
> +	return regmap_raw_read(chip->data.regmap, reg, val, sizeof(u8));
> +}
> +
> +static inline int max_tcpci_write8(struct max_tcpci_chip *chip, unsigned int reg, u8 val)
> +{
> +	return regmap_raw_write(chip->data.regmap, reg, &val, sizeof(u8));
> +}
> +
> +bool max_contaminant_is_contaminant(struct max_tcpci_chip *chip, bool disconnect_while_debounce);
> +
> +#endif  // TCPCI_MAXIM_H_
> diff --git a/drivers/usb/typec/tcpm/tcpci_maxim.c b/drivers/usb/typec/tcpm/tcpci_maxim_core.c
> similarity index 93%
> rename from drivers/usb/typec/tcpm/tcpci_maxim.c
> rename to drivers/usb/typec/tcpm/tcpci_maxim_core.c
> index 83e140ffcc3e..f32cda2a5e3a 100644
> --- a/drivers/usb/typec/tcpm/tcpci_maxim.c
> +++ b/drivers/usb/typec/tcpm/tcpci_maxim_core.c
> @@ -1,6 +1,6 @@
> -// SPDX-License-Identifier: GPL-2.0
> +// SPDX-License-Identifier: GPL-2.0+
>   /*
> - * Copyright (C) 2020, Google LLC
> + * Copyright (C) 2020 - 2022, Google LLC
>    *
>    * MAXIM TCPCI based TCPC driver
>    */
> @@ -15,6 +15,8 @@
>   #include <linux/usb/tcpm.h>
>   #include <linux/usb/typec.h>
>   
> +#include "tcpci_maxim.h"
> +
>   #define PD_ACTIVITY_TIMEOUT_MS				10000
>   
>   #define TCPC_VENDOR_ALERT				0x80
> @@ -39,14 +41,6 @@
>   #define MAX_BUCK_BOOST_SOURCE				0xa
>   #define MAX_BUCK_BOOST_SINK				0x5
>   
> -struct max_tcpci_chip {
> -	struct tcpci_data data;
> -	struct tcpci *tcpci;
> -	struct device *dev;
> -	struct i2c_client *client;
> -	struct tcpm_port *port;
> -};
> -
>   static const struct regmap_range max_tcpci_tcpci_range[] = {
>   	regmap_reg_range(0x00, 0x95)
>   };
> @@ -68,26 +62,6 @@ static struct max_tcpci_chip *tdata_to_max_tcpci(struct tcpci_data *tdata)
>   	return container_of(tdata, struct max_tcpci_chip, data);
>   }
>   
> -static int max_tcpci_read16(struct max_tcpci_chip *chip, unsigned int reg, u16 *val)
> -{
> -	return regmap_raw_read(chip->data.regmap, reg, val, sizeof(u16));
> -}
> -
> -static int max_tcpci_write16(struct max_tcpci_chip *chip, unsigned int reg, u16 val)
> -{
> -	return regmap_raw_write(chip->data.regmap, reg, &val, sizeof(u16));
> -}
> -
> -static int max_tcpci_read8(struct max_tcpci_chip *chip, unsigned int reg, u8 *val)
> -{
> -	return regmap_raw_read(chip->data.regmap, reg, val, sizeof(u8));
> -}
> -
> -static int max_tcpci_write8(struct max_tcpci_chip *chip, unsigned int reg, u8 val)
> -{
> -	return regmap_raw_write(chip->data.regmap, reg, &val, sizeof(u8));
> -}
> -
>   static void max_tcpci_init_regs(struct max_tcpci_chip *chip)
>   {
>   	u16 alert_mask = 0;
> @@ -348,8 +322,14 @@ static irqreturn_t _max_tcpci_irq(struct max_tcpci_chip *chip, u16 status)
>   	if (status & TCPC_ALERT_VBUS_DISCNCT)
>   		tcpm_vbus_change(chip->port);
>   
> -	if (status & TCPC_ALERT_CC_STATUS)
> -		tcpm_cc_change(chip->port);
> +	if (status & TCPC_ALERT_CC_STATUS) {
> +		if (chip->contaminant_state == DETECTED || tcpm_port_is_toggling(chip->port)) {
> +			if (!max_contaminant_is_contaminant(chip, false))
> +				tcpm_port_clean(chip->port);
> +		} else {
> +			tcpm_cc_change(chip->port);
> +		}
> +	}
>   
>   	if (status & TCPC_ALERT_POWER_STATUS)
>   		process_power_status(chip);
> @@ -438,6 +418,14 @@ static int tcpci_init(struct tcpci *tcpci, struct tcpci_data *data)
>   	return -1;
>   }
>   
> +static void max_tcpci_check_contaminant(struct tcpci *tcpci, struct tcpci_data *tdata)
> +{
> +	struct max_tcpci_chip *chip = tdata_to_max_tcpci(tdata);
> +
> +	if (!max_contaminant_is_contaminant(chip, true))
> +		tcpm_port_clean(chip->port);
> +}
> +
>   static int max_tcpci_probe(struct i2c_client *client)
>   {
>   	int ret;
> @@ -471,6 +459,7 @@ static int max_tcpci_probe(struct i2c_client *client)
>   	chip->data.auto_discharge_disconnect = true;
>   	chip->data.vbus_vsafe0v = true;
>   	chip->data.set_partner_usb_comm_capable = max_tcpci_set_partner_usb_comm_capable;
> +	chip->data.check_contaminant = max_tcpci_check_contaminant;
>   
>   	max_tcpci_init_regs(chip);
>   	chip->tcpci = tcpci_register_port(chip->dev, &chip->data);