Date:   Thu, 26 Jan 2023 13:23:48 +0000
From:   Lee Jones <lee@kernel.org>
To:     Fenglin Wu <quic_fenglinw@quicinc.com>
Cc:     linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        pavel@ucw.cz, krzysztof.kozlowski@linaro.org,
        Gene Chen <gene_chen@richtek.com>,
        Jacek Anaszewski <jacek.anaszewski@gmail.com>,
        linux-leds@vger.kernel.org, quic_collinsd@quicinc.com,
        quic_subbaram@quicinc.com, Luca Weiss <luca.weiss@fairphone.com>
Subject: Re: [RESEND PATCH v5 1/2] leds: flash: add driver to support flash
 LED module in QCOM PMICs
Message-ID: <Y9J+5OZQ5Fv60T3V@google.com>
References: <20221227081523.2277797-1-quic_fenglinw@quicinc.com>
 <20221227081523.2277797-2-quic_fenglinw@quicinc.com>
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In-Reply-To: <20221227081523.2277797-2-quic_fenglinw@quicinc.com>
Precedence: bulk

On Tue, 27 Dec 2022, Fenglin Wu wrote:

> Add initial driver to support flash LED module found in Qualcomm
> Technologies, Inc. PMICs. The flash module can have 3 or 4 channels
> and each channel can be controlled indepedently and support full scale
> current up to 1.5 A. It also supports connecting two channels together
> to supply one LED component with full scale current up to 2 A. In that
> case, the current will be split on each channel symmetrically and the
> channels will be enabled and disabled at the same time.
> 
> Signed-off-by: Fenglin Wu <quic_fenglinw@quicinc.com>
> Tested-by: Luca Weiss <luca.weiss@fairphone.com> # sm7225-fairphone-fp4 + pm6150l
> ---
>  drivers/leds/flash/Kconfig           |  15 +
>  drivers/leds/flash/Makefile          |   1 +
>  drivers/leds/flash/leds-qcom-flash.c | 701 +++++++++++++++++++++++++++
>  3 files changed, 717 insertions(+)
>  create mode 100644 drivers/leds/flash/leds-qcom-flash.c
> 
> diff --git a/drivers/leds/flash/Kconfig b/drivers/leds/flash/Kconfig
> index d3eb689b193c..f36a60409290 100644
> --- a/drivers/leds/flash/Kconfig
> +++ b/drivers/leds/flash/Kconfig
> @@ -61,6 +61,21 @@ config LEDS_MT6360
>  	  Independent current sources supply for each flash LED support torch
>  	  and strobe mode.
>  
> +config LEDS_QCOM_FLASH
> +	tristate "LED support for flash module inside Qualcomm Technologies, Inc. PMIC"
> +	depends on MFD_SPMI_PMIC || COMPILE_TEST
> +	depends on LEDS_CLASS && OF
> +	depends on V4L2_FLASH_LED_CLASS || !V4L2_FLASH_LED_CLASS
> +	select REGMAP
> +	help
> +	  This option enables support for the flash module found in Qualcomm
> +	  Technologies, Inc. PMICs. The flash module can have 3 or 4 flash LED
> +	  channels and each channel is programmable to support up to 1.5 A full
> +	  scale current. It also supports connecting two channels' output together
> +	  to supply one LED component to achieve current up to 2 A. In such case,
> +	  the total LED current will be split symmetrically on each channel and
> +	  they will be enabled/disabled at the same time.
> +
>  config LEDS_RT4505
>  	tristate "LED support for RT4505 flashlight controller"
>  	depends on I2C && OF
> diff --git a/drivers/leds/flash/Makefile b/drivers/leds/flash/Makefile
> index 0acbddc0b91b..8a60993f1a25 100644
> --- a/drivers/leds/flash/Makefile
> +++ b/drivers/leds/flash/Makefile
> @@ -6,6 +6,7 @@ obj-$(CONFIG_LEDS_AS3645A)	+= leds-as3645a.o
>  obj-$(CONFIG_LEDS_KTD2692)	+= leds-ktd2692.o
>  obj-$(CONFIG_LEDS_LM3601X)	+= leds-lm3601x.o
>  obj-$(CONFIG_LEDS_MAX77693)	+= leds-max77693.o
> +obj-$(CONFIG_LEDS_QCOM_FLASH)	+= leds-qcom-flash.o
>  obj-$(CONFIG_LEDS_RT4505)	+= leds-rt4505.o
>  obj-$(CONFIG_LEDS_RT8515)	+= leds-rt8515.o
>  obj-$(CONFIG_LEDS_SGM3140)	+= leds-sgm3140.o
> diff --git a/drivers/leds/flash/leds-qcom-flash.c b/drivers/leds/flash/leds-qcom-flash.c
> new file mode 100644
> index 000000000000..3735282b77e9
> --- /dev/null
> +++ b/drivers/leds/flash/leds-qcom-flash.c
> @@ -0,0 +1,701 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/bits.h>
> +#include <linux/leds.h>
> +#include <linux/led-class-flash.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +#include <linux/regmap.h>
> +#include <media/v4l2-flash-led-class.h>
> +
> +/* registers definitions */
> +#define FLASH_TYPE_REG			0x04
> +#define FLASH_TYPE_VAL			0x18
> +
> +#define FLASH_SUBTYPE_REG		0x05
> +#define FLASH_SUBTYPE_3CH_VAL		0x04
> +#define FLASH_SUBTYPE_4CH_VAL		0x07
> +
> +#define FLASH_TIMER_EN_BIT		BIT(7)
> +#define FLASH_TIMER_VAL_MASK		GENMASK(6, 0)
> +#define FLASH_TIMER_STEP_MS		10
> +
> +#define FLASH_STROBE_HW_SW_SEL_BIT	BIT(2)
> +#define SW_STROBE_VAL			0
> +#define HW_STROBE_VAL			1
> +#define FLASH_HW_STROBE_TRIGGER_SEL_BIT	BIT(1)
> +#define STROBE_LEVEL_TRIGGER_VAL	0
> +#define STROBE_EDGE_TRIGGER_VAL		1
> +#define FLASH_STROBE_POLARITY_BIT	BIT(0)
> +#define STROBE_ACTIVE_HIGH_VAL		1
> +
> +#define FLASH_IRES_MASK_4CH		BIT(0)
> +#define FLASH_IRES_MASK_3CH		GENMASK(1, 0)
> +#define FLASH_IRES_12P5MA_VAL		0
> +#define FLASH_IRES_5MA_VAL_4CH		1
> +#define FLASH_IRES_5MA_VAL_3CH		3
> +
> +/* constants */
> +#define FLASH_CURRENT_MAX_UA		1500000
> +#define TORCH_CURRENT_MAX_UA		500000
> +#define FLASH_TOTAL_CURRENT_MAX_UA	2000000
> +#define FLASH_CURRENT_DEFAULT_UA	1000000
> +#define TORCH_CURRENT_DEFAULT_UA	200000
> +
> +#define TORCH_IRES_UA			5000
> +#define FLASH_IRES_UA			12500
> +
> +#define FLASH_TIMEOUT_MAX_US		1280000
> +#define FLASH_TIMEOUT_STEP_US		10000
> +
> +enum hw_type {
> +	QCOM_MVFLASH_3CH,
> +	QCOM_MVFLASH_4CH,
> +};
> +
> +enum led_mode {
> +	FLASH_MODE,
> +	TORCH_MODE,
> +};
> +
> +enum led_strobe {
> +	SW_STROBE,
> +	HW_STROBE,
> +};
> +
> +enum {
> +	REG_STATUS1,
> +	REG_STATUS2,
> +	REG_STATUS3,
> +	REG_CHAN_TIMER,
> +	REG_ITARGET,
> +	REG_MODULE_EN,
> +	REG_IRESOLUTION,
> +	REG_CHAN_STROBE,
> +	REG_CHAN_EN,
> +	REG_MAX_COUNT,
> +};
> +
> +struct reg_field mvflash_3ch_regs[REG_MAX_COUNT] = {
> +	REG_FIELD(0x08, 0, 7),			/* status1	*/
> +	REG_FIELD(0x09, 0, 7),                  /* status2	*/
> +	REG_FIELD(0x0a, 0, 7),                  /* status3	*/
> +	REG_FIELD_ID(0x40, 0, 7, 3, 1),         /* chan_timer	*/
> +	REG_FIELD_ID(0x43, 0, 6, 3, 1),         /* itarget	*/
> +	REG_FIELD(0x46, 7, 7),                  /* module_en	*/
> +	REG_FIELD(0x47, 0, 5),                  /* iresolution	*/
> +	REG_FIELD_ID(0x49, 0, 2, 3, 1),         /* chan_strobe	*/
> +	REG_FIELD(0x4c, 0, 2),                  /* chan_en	*/
> +};
> +
> +struct reg_field mvflash_4ch_regs[REG_MAX_COUNT] = {
> +	REG_FIELD(0x06, 0, 7),			/* status1	*/
> +	REG_FIELD(0x07, 0, 6),			/* status2	*/
> +	REG_FIELD(0x09, 0, 7),			/* status3	*/
> +	REG_FIELD_ID(0x3e, 0, 7, 4, 1),		/* chan_timer	*/
> +	REG_FIELD_ID(0x42, 0, 6, 4, 1),		/* itarget	*/
> +	REG_FIELD(0x46, 7, 7),			/* module_en	*/
> +	REG_FIELD(0x49, 0, 3),			/* iresolution	*/
> +	REG_FIELD_ID(0x4a, 0, 6, 4, 1),		/* chan_strobe	*/
> +	REG_FIELD(0x4e, 0, 3),			/* chan_en	*/
> +};
> +
> +struct qcom_flash_led {
> +	struct qcom_flash_chip		*chip;

Not a fan of these interwoven references.  Where 'chip' has a reverence
to 'led' and 'led' has a reference to 'chip'.

  chip->leds[0]->chip->leds[0]->chip ...

Either re-work your API (pass 'chip' and an LED index for example [this
may very well not be the correct solution) or use something akin to
container_of().

> +	struct led_classdev_flash	flash;
> +	struct v4l2_flash		*v4l2_flash;
> +	u32				max_flash_current_ma;
> +	u32				max_torch_current_ma;
> +	u32				max_timeout_ms;
> +	u32				flash_current_ma;
> +	u32				flash_timeout_ms;
> +	u8				*chan_id;
> +	u8				chan_count;
> +	bool				enabled;
> +};
> +
> +struct qcom_flash_chip {
> +	struct qcom_flash_led	*leds;
> +	struct regmap_field     *r_fields[REG_MAX_COUNT];
> +	struct device		*dev;
> +	struct mutex		lock;
> +	enum hw_type		hw_type;
> +	u8			leds_count;
> +	u8			max_channels;
> +	u8			chan_en_bits;
> +};
> +
> +static int set_flash_module_en(struct qcom_flash_led *led, bool en)
> +{
> +	struct qcom_flash_chip *chip = led->chip;
> +	u8 led_mask = 0, val;
> +	int i, rc;
> +
> +	for (i = 0; i < led->chan_count; i++)
> +		led_mask |= BIT(led->chan_id[i] - 1);
> +
> +	mutex_lock(&chip->lock);
> +	if (en)
> +		chip->chan_en_bits |= led_mask;
> +	else
> +		chip->chan_en_bits &= ~led_mask;
> +
> +	val = !!chip->chan_en_bits;
> +	rc = regmap_field_write(chip->r_fields[REG_MODULE_EN], val);

I'm a little confused by this.

So we go through the process of flipping individual enable bits, then
trash all of that knowledge and end up writing an individual 0 or 1.

Why not replace the whole function with:

    regmap_field_write(chip->r_fields[REG_MODULE_EN], en);

> +	if (rc < 0)
> +		dev_err(chip->dev, "write module_en failed, rc=%d\n", rc);
> +	mutex_unlock(&chip->lock);
> +
> +	return rc;
> +}
> +
> +static int set_flash_current(struct qcom_flash_led *led, u32 current_ma, enum led_mode mode)
> +{
> +	struct qcom_flash_chip *chip = led->chip;
> +	u32 itarg_ua = current_ma * 1000 / led->chan_count + 1;

Please make it clear what you're doing here.

I suggest you separate the allocation and the assignment and add a
comment to the latter.

> +	u32 ires_ua = (mode == FLASH_MODE) ? FLASH_IRES_UA : TORCH_IRES_UA;
> +	u8 val, shift, ires_mask = 0, ires_val = 0, chan_id;
> +	int i, rc;
> +
> +	/*
> +	 * Split the current across the channels and set the
> +	 * IRESOLUTION and ITARGET registers accordingly.
> +	 */
> +	for (i = 0; i < led->chan_count; i++) {
> +		chan_id = led->chan_id[i];
> +		if (itarg_ua < ires_ua)
> +			val = 0;

If you allocate 'val' in here and pre-assign it, you can negate the
logic and omit this branch.  Unless this is going to be multi-use, 'val'
is not a great name for a variable.

> +		else
> +			val = itarg_ua / ires_ua - 1;
> +
> +		rc = regmap_fields_write(chip->r_fields[REG_ITARGET], chan_id - 1, val);

Instead of '-1'ing every time you wish to use the value, why don't you
start the numbering off at 0 instead?  If that's not possible, take 1
off when you initially assign it.

> +		if (rc < 0)
> +			return rc;
> +
> +		if (chip->hw_type == QCOM_MVFLASH_3CH) {
> +			shift = (chan_id - 1) * 2;
> +			ires_mask |= FLASH_IRES_MASK_3CH << shift;
> +			ires_val |= ((mode == FLASH_MODE) ?
> +				(FLASH_IRES_12P5MA_VAL << shift) :
> +				(FLASH_IRES_5MA_VAL_3CH << shift));
> +		} else if (chip->hw_type == QCOM_MVFLASH_4CH) {
> +			shift = chan_id - 1;
> +			ires_mask |= FLASH_IRES_MASK_4CH << shift;
> +			ires_val |= ((mode == FLASH_MODE) ?
> +				(FLASH_IRES_12P5MA_VAL << shift) :
> +				(FLASH_IRES_5MA_VAL_4CH << shift));
> +		}

... else do something unexpected?

> +	}
> +
> +	return regmap_field_update_bits(chip->r_fields[REG_IRESOLUTION], ires_mask, ires_val);
> +}
> +
> +static int set_flash_timeout(struct qcom_flash_led *led, u32 timeout_ms)
> +{
> +	struct qcom_flash_chip *chip = led->chip;
> +	u8 val, chan_id;
> +	int rc, i;
> +
> +	/* set SAFETY_TIMER for all the channels connected to the same LED */
> +	timeout_ms = min_t(u32, timeout_ms, led->max_timeout_ms);
> +	for (i = 0; i < led->chan_count; i++) {
> +		chan_id = led->chan_id[i];
> +		val = timeout_ms / FLASH_TIMER_STEP_MS;
> +		val = clamp_t(u8, val, 0, FLASH_TIMER_VAL_MASK);
> +		if (timeout_ms)
> +			val |= FLASH_TIMER_EN_BIT;

Nit: This if doesn't have anything to do with the line above.  If you
were to space them out (with a '\n') some sections would be easier to
read.  Please also apply this logic to the rest of the file.

> +
> +		rc = regmap_fields_write(chip->r_fields[REG_CHAN_TIMER], chan_id - 1, val);
> +		if (rc < 0)
> +			return rc;
> +	}
> +
> +	return 0;
> +}
> +
> +static int set_flash_strobe(struct qcom_flash_led *led, enum led_strobe strobe, bool state)
> +{
> +	struct qcom_flash_chip *chip = led->chip;
> +	u8 mask, val, chan_id = 0, chan_mask = 0;
> +	int rc, i;
> +
> +	/* Set SW strobe config for all channels connected to the LED */
> +	for (i = 0; i < led->chan_count; i++) {
> +		chan_id = led->chan_id[i];
> +		if (strobe == SW_STROBE)
> +			val = FIELD_PREP(FLASH_STROBE_HW_SW_SEL_BIT, SW_STROBE_VAL);
> +		else
> +			val = FIELD_PREP(FLASH_STROBE_HW_SW_SEL_BIT, HW_STROBE_VAL);
> +
> +		val |= FIELD_PREP(FLASH_HW_STROBE_TRIGGER_SEL_BIT, STROBE_LEVEL_TRIGGER_VAL) |
> +			FIELD_PREP(FLASH_STROBE_POLARITY_BIT, STROBE_ACTIVE_HIGH_VAL);
> +		rc = regmap_fields_write(chip->r_fields[REG_CHAN_STROBE], chan_id - 1, val);
> +		if (rc < 0)
> +			return rc;
> +
> +		chan_mask |= BIT(chan_id - 1);
> +	}
> +
> +	/* enable/disable flash channels */

Nit: "Enable"

> +	mask = chan_mask;

Why can't you just use chan_mask?

> +	val = state ? mask : 0;
> +	rc = regmap_field_update_bits(chip->r_fields[REG_CHAN_EN], mask, val);
> +	if (rc < 0)
> +		return rc;
> +
> +	led->enabled = state;
> +	return 0;
> +}
> +
> +static int qcom_flash_brightness_set(struct led_classdev_flash *fled_cdev, u32 brightness)
> +{
> +	struct qcom_flash_led *led = container_of(fled_cdev, struct qcom_flash_led, flash);
> +
> +	led->flash_current_ma = min_t(u32, led->max_flash_current_ma, brightness / 1000);

No magic numbers please.

Can you define the 1000 or use a MACRO instead please?

Same throughout.

> +	return 0;
> +}
> +
> +static int qcom_flash_timeout_set(struct led_classdev_flash *fled_cdev, u32 timeout)
> +{
> +	struct qcom_flash_led *led = container_of(fled_cdev, struct qcom_flash_led, flash);
> +
> +	led->flash_timeout_ms = timeout / 1000;
> +	return 0;
> +}
> +
> +static int qcom_flash_strobe_set(struct led_classdev_flash *fled_cdev, bool state)
> +{
> +	struct qcom_flash_led *led = container_of(fled_cdev, struct qcom_flash_led, flash);
> +	int rc;
> +
> +	rc = set_flash_current(led, led->flash_current_ma, FLASH_MODE);
> +	if (rc < 0)

These can all be simplified to 'if (rc)'?

> +		return rc;
> +
> +	rc = set_flash_timeout(led, led->flash_timeout_ms);
> +	if (rc < 0)
> +		return rc;
> +
> +	rc = set_flash_module_en(led, state);
> +	if (rc < 0)
> +		return rc;
> +
> +	return set_flash_strobe(led, SW_STROBE, state);
> +}
> +
> +static int qcom_flash_strobe_get(struct led_classdev_flash *fled_cdev, bool *state)

Why do you use the qcom_ prefix sometimes and not others?

> +{
> +	struct qcom_flash_led *led = container_of(fled_cdev, struct qcom_flash_led, flash);
> +
> +	*state = led->enabled;
> +	return 0;
> +}
> +
> +static int qcom_flash_fault_get(struct led_classdev_flash *fled_cdev, u32 *fault)
> +{
> +	struct qcom_flash_led *led = container_of(fled_cdev, struct qcom_flash_led, flash);
> +	struct qcom_flash_chip *chip = led->chip;
> +	u8 shift, chan_id = 0, chan_mask = 0;
> +	u8 ot_mask = 0, oc_mask = 0, uv_mask = 0;
> +	u32 val, fault_sts = 0;
> +	int i, rc;
> +
> +	rc = regmap_field_read(chip->r_fields[REG_STATUS1], &val);
> +	if (rc < 0)
> +		return rc;
> +
> +	for (i = 0; i < led->chan_count; i++) {
> +		chan_id = led->chan_id[i];
> +		shift = (chan_id - 1) * 2;
> +		if (val & BIT(shift))
> +			fault_sts |= LED_FAULT_SHORT_CIRCUIT;
> +		chan_mask |= BIT(chan_id - 1);
> +	}
> +
> +	rc = regmap_field_read(chip->r_fields[REG_STATUS2], &val);
> +	if (rc < 0)
> +		return rc;
> +
> +	if (chip->hw_type == QCOM_MVFLASH_3CH) {
> +		ot_mask = 0x0f;
> +		oc_mask = 0xe0;
> +		uv_mask = 0x10;
> +	} else if (chip->hw_type == QCOM_MVFLASH_4CH) {
> +		ot_mask = 0x70;
> +		oc_mask = 0x0e;
> +		uv_mask = 0x01;
> +	}

No magic numbers please.

> +	if (val & ot_mask)
> +		fault_sts |= LED_FAULT_OVER_TEMPERATURE;
> +	if (val & oc_mask)
> +		fault_sts |= LED_FAULT_OVER_CURRENT;
> +	if (val & uv_mask)
> +		fault_sts |= LED_FAULT_INPUT_VOLTAGE;
> +
> +	rc = regmap_field_read(chip->r_fields[REG_STATUS3], &val);
> +	if (rc < 0)
> +		return rc;
> +
> +	if (chip->hw_type == QCOM_MVFLASH_3CH) {
> +		if (val & chan_mask)
> +			fault_sts |= LED_FAULT_TIMEOUT;
> +	} else if (chip->hw_type == QCOM_MVFLASH_4CH) {
> +		for (i = 0; i < led->chan_count; i++) {
> +			chan_id = led->chan_id[i];
> +			shift = (chan_id - 1) * 2;
> +			if (val & BIT(shift))
> +				fault_sts |= LED_FAULT_TIMEOUT;
> +		}
> +	}
> +
> +	*fault = fault_sts;
> +	return 0;
> +}
> +
> +static int qcom_flash_led_brightness_set(struct led_classdev *led_cdev,
> +					enum led_brightness brightness)
> +{
> +	struct led_classdev_flash *fled_cdev =
> +		container_of(led_cdev, struct led_classdev_flash, led_cdev);
> +	struct qcom_flash_led *led =
> +		container_of(fled_cdev, struct qcom_flash_led, flash);
> +	u32 current_ma = brightness * led->max_torch_current_ma / LED_FULL;
> +	bool enable = !!brightness;
> +	int rc;
> +
> +	rc = set_flash_current(led, current_ma, TORCH_MODE);
> +	if (rc < 0)
> +		return rc;
> +
> +	/* disable flash timeout for torch LED */

Nit: "Disable"

> +	rc = set_flash_timeout(led, 0);
> +	if (rc < 0)
> +		return rc;
> +
> +	rc = set_flash_module_en(led, enable);
> +	if (rc < 0)
> +		return rc;
> +
> +	return set_flash_strobe(led, SW_STROBE, enable);
> +}
> +
> +static const struct led_flash_ops qcom_flash_ops = {
> +	.flash_brightness_set = qcom_flash_brightness_set,
> +	.strobe_set = qcom_flash_strobe_set,
> +	.strobe_get = qcom_flash_strobe_get,
> +	.timeout_set = qcom_flash_timeout_set,
> +	.fault_get = qcom_flash_fault_get,
> +};
> +
> +#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
> +static int qcom_flash_external_strobe_set(struct v4l2_flash *v4l2_flash, bool enable)
> +{
> +	struct led_classdev_flash *flash = v4l2_flash->fled_cdev;
> +	struct qcom_flash_led *led = container_of(flash, struct qcom_flash_led, flash);
> +	int rc;
> +
> +	rc = set_flash_module_en(led, enable);
> +	if (rc < 0)
> +		return rc;
> +
> +	if (enable)
> +		return set_flash_strobe(led, HW_STROBE, true);
> +	else
> +		return set_flash_strobe(led, SW_STROBE, false);
> +}
> +
> +static enum led_brightness qcom_flash_intensity_to_led_brightness(
> +		 struct v4l2_flash *v4l2_flash, s32 intensity)

This is an ugly way to break a line.  Suggest this:

static enum led_brightness
qcom_flash_intensity_to_led_brightness(struct v4l2_flash *v4l2_flash, s32 intensity)

> +{
> +	struct led_classdev_flash *flash = v4l2_flash->fled_cdev;
> +	struct qcom_flash_led *led = container_of(flash, struct qcom_flash_led, flash);
> +	u32 current_ma = intensity / 1000;
> +
> +	current_ma = min_t(u32, current_ma, led->max_torch_current_ma);
> +	if (!current_ma)
> +		return LED_OFF;
> +
> +	return current_ma * LED_FULL / led->max_torch_current_ma;

Suggest some additional bracketing here.

> +}
> +
> +static s32 qcom_flash_brightness_to_led_intensity(struct v4l2_flash *v4l2_flash,
> +					enum led_brightness brightness)
> +{
> +	struct led_classdev_flash *flash = v4l2_flash->fled_cdev;
> +	struct qcom_flash_led *led = container_of(flash, struct qcom_flash_led, flash);
> +
> +	return (brightness * led->max_torch_current_ma * 1000) / LED_FULL;
> +}
> +
> +static const struct v4l2_flash_ops qcom_v4l2_flash_ops = {
> +	.external_strobe_set = qcom_flash_external_strobe_set,
> +	.intensity_to_led_brightness = qcom_flash_intensity_to_led_brightness,
> +	.led_brightness_to_intensity = qcom_flash_brightness_to_led_intensity,
> +};
> +
> +static int qcom_flash_v4l2_init(struct qcom_flash_led *led, struct fwnode_handle *fwnode)
> +{
> +	struct v4l2_flash_config v4l2_cfg = {0};

Nit: Spaces around the 0 please.

> +	struct led_flash_setting *s = &v4l2_cfg.intensity;
> +
> +	if (!(led->flash.led_cdev.flags & LED_DEV_CAP_FLASH))
> +		return 0;
> +
> +	s->min = s->step = TORCH_IRES_UA * led->chan_count;
> +	s->max = led->max_torch_current_ma * 1000;
> +	s->val = min_t(u32, s->max, TORCH_CURRENT_DEFAULT_UA);
> +
> +	strscpy(v4l2_cfg.dev_name, led->flash.led_cdev.dev->kobj.name,
> +					sizeof(v4l2_cfg.dev_name));
> +	v4l2_cfg.has_external_strobe = 1;

This is a bool.

> +	v4l2_cfg.flash_faults = LED_FAULT_INPUT_VOLTAGE | LED_FAULT_OVER_CURRENT |
> +		LED_FAULT_SHORT_CIRCUIT | LED_FAULT_OVER_TEMPERATURE | LED_FAULT_TIMEOUT;

	v4l2_cfg.flash_faults = LED_FAULT_INPUT_VOLTAGE |
				LED_FAULT_OVER_CURRENT |
				LED_FAULT_SHORT_CIRCUIT |
				LED_FAULT_OVER_TEMPERATURE |
				LED_FAULT_TIMEOUT;

Don't you think that's nicer to read?

> +	led->v4l2_flash = v4l2_flash_init(led->chip->dev, fwnode, &led->flash,
> +					&qcom_v4l2_flash_ops, &v4l2_cfg);
> +	return PTR_ERR_OR_ZERO(led->v4l2_flash);
> +}
> +# else
> +static int qcom_flash_v4l2_init(struct qcom_flash_led *led, struct fwnode_handle *fwnode)
> +{
> +	return 0;
> +}
> +#endif
> +
> +static int qcom_flash_register_led_device(struct device *parent,
> +		struct fwnode_handle *node, struct qcom_flash_led *led)
> +{
> +	struct qcom_flash_chip *chip = led->chip;
> +	struct led_init_data init_data;
> +	struct led_classdev_flash *flash;
> +	struct led_flash_setting *s;
> +	u32 count, val;
> +	u32 channels[4];
> +	int i, rc;
> +
> +	flash = &led->flash;

a) this has nothing to do with the following line, so you should
separate it and b) I don't see any reason not to place the assignment
on the allocate line.

> +	count = fwnode_property_count_u32(node, "led-sources");
> +	if (count <= 0) {
> +		dev_err(chip->dev, "No led-sources specified\n");
> +		return -ENODEV;
> +	}
> +
> +	if (count > chip->max_channels) {
> +		dev_err(chip->dev, "led-sources count %u exceeds maximum channel count %u\n",
> +				count, chip->max_channels);
> +		return -EINVAL;
> +	}
> +
> +	rc = fwnode_property_read_u32_array(node, "led-sources", channels, count);
> +	if (rc < 0) {
> +		dev_err(chip->dev, "get led-sources failed, rc=%d\n", rc);
> +		return rc;
> +	}
> +
> +	led->chan_count = count;
> +	led->chan_id = devm_kcalloc(chip->dev, count, sizeof(u8), GFP_KERNEL);
> +	if (!led->chan_id)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < count; i++) {
> +		if (channels[i] > chip->max_channels) {
> +			dev_err(chip->dev, "led-source out of HW support range [1-%u]\n",
> +					chip->max_channels);
> +			return -EINVAL;
> +		}
> +
> +		led->chan_id[i] = channels[i];
> +	}
> +
> +	rc = fwnode_property_read_u32(node, "led-max-microamp", &val);
> +	if (rc < 0) {
> +		dev_err(chip->dev, "Get led-max-microamp failed, rc=%d\n", rc);

"Failed to read led-max-microamp property"

> +		return rc;
> +	}
> +
> +	if (!val) {
> +		dev_err(chip->dev, "led-max-microamp shouldn't be 0\n");
> +		return -EINVAL;
> +	}
> +
> +	val = min_t(u32, val, TORCH_CURRENT_MAX_UA * led->chan_count);
> +	led->max_torch_current_ma = val / 1000;
> +
> +	if (fwnode_property_present(node, "flash-max-microamp")) {
> +		flash->led_cdev.flags |= LED_DEV_CAP_FLASH;
> +		rc = fwnode_property_read_u32(node, "flash-max-microamp", &val);
> +		if (rc < 0) {
> +			dev_err(chip->dev, "Get flash-max-microamp failed, rc=%d\n", rc);

As above.

> +			return rc;
> +		}
> +
> +		val = min_t(u32, val, FLASH_CURRENT_MAX_UA * led->chan_count);
> +		val = min_t(u32, val, FLASH_TOTAL_CURRENT_MAX_UA);
> +		s = &flash->brightness;

's' is not a good variable name.

> +		s->min = s->step = FLASH_IRES_UA * led->chan_count;

These get over-written before they are used.

Scrap that, I see that 's' gets reassigned.

Even more reason to change 's' for something else and use 2 variables
instead of one to make this point clear.

A few comments spread around the complex areas wouldn't go amiss either.

> +		s->max = val;
> +		s->val = min_t(u32, val, FLASH_CURRENT_DEFAULT_UA);
> +		led->max_flash_current_ma = val / 1000;
> +		led->flash_current_ma = s->val / 1000;
> +
> +		rc = fwnode_property_read_u32(node, "flash-max-timeout-us", &val);
> +		if (rc < 0) {
> +			dev_err(chip->dev, "Get flash-max-timeout-us failed, rc=%d\n", rc);
> +			return rc;
> +		}
> +
> +		val = min_t(u32, val, FLASH_TIMEOUT_MAX_US);
> +		s = &flash->timeout;
> +		s->min = s->step = FLASH_TIMEOUT_STEP_US;
> +		s->val = s->max = val;
> +		led->max_timeout_ms = led->flash_timeout_ms = val / 1000;
> +
> +		flash->ops = &qcom_flash_ops;
> +	}
> +
> +	flash->led_cdev.brightness_set_blocking = qcom_flash_led_brightness_set;
> +	init_data.fwnode = node;
> +	init_data.devicename = NULL;
> +	init_data.default_label = NULL;
> +	init_data.devname_mandatory = false;

'\n'

> +	rc = devm_led_classdev_flash_register_ext(parent, flash, &init_data);
> +	if (rc < 0) {
> +		dev_err(chip->dev, "Register flash LED classdev failed, rc=%d\n", rc);
> +		return rc;
> +	}
> +
> +	return qcom_flash_v4l2_init(led, node);
> +}
> +
> +static int qcom_flash_led_probe(struct platform_device *pdev)
> +{
> +	struct qcom_flash_chip *chip;
> +	struct qcom_flash_led *led;
> +	struct fwnode_handle *child;
> +	struct device *dev = &pdev->dev;
> +	struct regmap *map;
> +	struct reg_field *regs;
> +	int count, i, rc;
> +	u32 val, reg_base;
> +
> +	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
> +	if (!chip)
> +		return -ENOMEM;
> +
> +	map = dev_get_regmap(dev->parent, NULL);

Can you use 'regmap' here please.

> +	if (!map) {
> +		dev_err(dev, "Failed to get parent regmap\n");
> +		return -EINVAL;
> +	}
> +
> +	rc = fwnode_property_read_u32(dev->fwnode, "reg", &reg_base);
> +	if (rc < 0) {
> +		dev_err(dev, "Failed to get register base address, rc=%d\n", rc);
> +		return rc;
> +	}
> +
> +	rc = regmap_read(map, reg_base + FLASH_TYPE_REG, &val);
> +	if (rc < 0) {
> +		dev_err(dev, "Read flash module type failed, rc=%d\n", rc);
> +		return rc;
> +	}
> +
> +	if (val != FLASH_TYPE_VAL) {
> +		dev_err(dev, "type %#x is not a flash module\n", val);

Can we be more specific?  Flash to me is a memory devices.

> +		return -ENODEV;
> +	}
> +
> +	rc = regmap_read(map, reg_base + FLASH_SUBTYPE_REG, &val);
> +	if (rc < 0) {
> +		dev_err(dev, "Read flash module subtype failed, rc=%d\n", rc);
> +		return rc;
> +	}
> +
> +	if (val == FLASH_SUBTYPE_3CH_VAL) {
> +		chip->hw_type = QCOM_MVFLASH_3CH;
> +		chip->max_channels = 3;
> +		regs = mvflash_3ch_regs;
> +	} else if (val == FLASH_SUBTYPE_4CH_VAL) {
> +		chip->hw_type = QCOM_MVFLASH_4CH;
> +		chip->max_channels = 4;
> +		regs = mvflash_4ch_regs;
> +	} else {
> +		dev_err(dev, "flash subtype %#x is not yet supported\n", val);
> +		return -ENODEV;
> +	}
> +
> +	for (i = 0; i < REG_MAX_COUNT; i++)
> +		regs[i].reg += reg_base;
> +
> +	rc = devm_regmap_field_bulk_alloc(dev, map, chip->r_fields, regs, REG_MAX_COUNT);
> +	if (rc < 0) {
> +		dev_err(dev, "failed to alloc regmap filed, rc=%d\n", rc);

"Failed to allocate ..."

"field"

> +		return rc;
> +	}
> +
> +	chip->dev = dev;
> +	platform_set_drvdata(pdev, chip);
> +	mutex_init(&chip->lock);

'\n'

Lots of other places too - please refrain from smooshing code together.

> +	count = device_get_child_node_count(dev);
> +	if (count == 0 || count > chip->max_channels) {
> +		dev_err(dev, "No child or child count exceeds %d\n", chip->max_channels);
> +		return -EINVAL;
> +	}
> +
> +	chip->leds = devm_kcalloc(dev, count, sizeof(*chip->leds), GFP_KERNEL);
> +	if (!chip->leds)
> +		return -ENOMEM;
> +
> +	device_for_each_child_node(dev, child) {
> +		led = &chip->leds[chip->leds_count];
> +		led->chip = chip;
> +		rc = qcom_flash_register_led_device(dev, child, led);
> +		if (rc < 0)
> +			goto release;
> +
> +		chip->leds_count++;
> +	}
> +
> +	return 0;

'\n'

> +release:
> +	while (chip->leds && chip->leds_count--)
> +		v4l2_flash_release(chip->leds[chip->leds_count].v4l2_flash);
> +	return rc;
> +}
> +
> +static int qcom_flash_led_remove(struct platform_device *pdev)
> +{
> +	struct qcom_flash_chip *chip = platform_get_drvdata(pdev);
> +
> +	while (chip->leds_count--)
> +		v4l2_flash_release(chip->leds[chip->leds_count].v4l2_flash);
> +
> +	mutex_destroy(&chip->lock);
> +	return 0;
> +}
> +
> +static const struct of_device_id qcom_flash_led_match_table[] = {
> +	{ .compatible = "qcom,spmi-flash-led" },
> +	{ }
> +};
> +
> +MODULE_DEVICE_TABLE(of, qcom_flash_led_match_table);
> +static struct platform_driver qcom_flash_led_driver = {
> +	.driver = {
> +		.name = "leds-qcom-flash",
> +		.of_match_table = qcom_flash_led_match_table,
> +	},
> +	.probe = qcom_flash_led_probe,
> +	.remove = qcom_flash_led_remove,
> +};
> +
> +module_platform_driver(qcom_flash_led_driver);
> +
> +MODULE_DESCRIPTION("QCOM Flash LED driver");
> +MODULE_LICENSE("GPL");
> -- 
> 2.25.1
> 

-- 
Lee Jones [李琼斯]