Message-ID: <20150625174004.GL3276@localhost.localdomain>
Date:	Thu, 25 Jun 2015 20:40:04 +0300
From:	Sergei Zviagintsev <sergei@...v.net>
To:	Adriana Reus <adriana.reus@...el.com>
Cc:	jic23@...nel.org, linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: light: Add support for TXC PA12 als and proximity
 sensor

Hi,

I just was walking around and decided to look inside this driver :)
I left some comments below.

On Fri, Jun 26, 2015 at 01:29:22PM +0300, Adriana Reus wrote:
   ^^^
Your message came from future.

> Add support for TXC PA12203001 als and proximity sensor.
> Support for raw illuminance and proximity readings.
> 
> Signed-off-by: Adriana Reus <adriana.reus@...el.com>
> ---
>  drivers/iio/light/Kconfig      |  11 +
>  drivers/iio/light/Makefile     |   1 +
>  drivers/iio/light/pa12203001.c | 501 +++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 513 insertions(+)
>  create mode 100644 drivers/iio/light/pa12203001.c
> 
> diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
> index e6198b7..30fd835 100644
> --- a/drivers/iio/light/Kconfig
> +++ b/drivers/iio/light/Kconfig
> @@ -198,6 +198,17 @@ config LTR501
>  	 This driver can also be built as a module.  If so, the module
>           will be called ltr501.
>  
> +config PA12203001
> +        tristate "TXC PA12203001 light and proximity sensor"
> +        depends on I2C
> +        select REGMAP_I2C
> +        help
> +         If you say yes here you get support for the TXC PA12203001
> +         ambient light and proximity sensor.
> +
> +         This driver can also be built as a module.  If so, the module
> +         will be called pa12203001.
> +
>  config STK3310
>  	tristate "STK3310 ALS and proximity sensor"
>  	depends on I2C
> diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
> index e2d50fd..257fabd 100644
> --- a/drivers/iio/light/Makefile
> +++ b/drivers/iio/light/Makefile
> @@ -19,6 +19,7 @@ obj-$(CONFIG_ISL29125)		+= isl29125.o
>  obj-$(CONFIG_JSA1212)		+= jsa1212.o
>  obj-$(CONFIG_SENSORS_LM3533)	+= lm3533-als.o
>  obj-$(CONFIG_LTR501)		+= ltr501.o
> +obj-$(CONFIG_PA12203001)	+= pa12203001.o
>  obj-$(CONFIG_SENSORS_TSL2563)	+= tsl2563.o
>  obj-$(CONFIG_STK3310)          += stk3310.o
>  obj-$(CONFIG_TCS3414)		+= tcs3414.o
> diff --git a/drivers/iio/light/pa12203001.c b/drivers/iio/light/pa12203001.c
> new file mode 100644
> index 0000000..03bee4c
> --- /dev/null
> +++ b/drivers/iio/light/pa12203001.c
> @@ -0,0 +1,501 @@
> +/*
> + * Copyright (c) 2015 Intel Corporation
> + *
> + * Driver for TXC PA12203001 Proximity and Ambient Light Sensor.
> + *
> + * 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.
> + * To do: Interrupt support.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/acpi.h>
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/mutex.h>
> +#include <linux/pm.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/regmap.h>
> +
> +#define PA12203001_DRIVER_NAME	"pa12203001"
> +
> +#define PA12203001_REG_CFG0		0x00
> +#define PA12203001_REG_CFG1		0x01
> +#define PA12203001_REG_CFG2		0x02
> +#define PA12203001_REG_CFG3		0x03
> +
> +#define PA12203001_REG_ADL		0x0b
> +#define PA12203001_REG_PDH		0x0e
> +
> +#define PA12203001_REG_POFS		0x10
> +#define PA12203001_REG_PSET		0x11
> +
> +#define PA12203001_ALS_EN_MASK		BIT(0)
> +#define PA12203001_PX_EN_MASK		BIT(1)
> +#define PA12203001_PX_NORMAL_MODE_MASK		(BIT(7) | BIT(6))
> +#define PA12203001_AFSR_MASK		(BIT(5) | BIT(4))
> +
> +#define PA12203001_PSCAN			0x03
> +
> +/* als range 31000, ps, als disabled */
> +#define PA12203001_REG_CFG0_DEFAULT		0x30
> +
> +/* led current: 100 mA */
> +#define PA12203001_REG_CFG1_DEFAULT		0x10
> +
> +/* ps mode: normal, interrupts not active */
> +#define PA12203001_REG_CFG2_DEFAULT		0xcc
> +
> +#define PA12203001_REG_CFG3_DEFAULT		0x00
> +
> +#define PA12203001_SLEEP_DELAY_MS		3000
> +
> +/* available scales: corresponding to [500, 4000, 7000, 31000]  lux */
> +static const int pa12203001_scales[] = { 7629, 61036, 106813, 473029};
> +
> +struct pa12203001_data {
> +	struct i2c_client *client;
> +
> +	/* protect device states */
> +	struct mutex lock;
> +
> +	bool als_enabled;
> +	bool px_enabled;
> +	bool als_needs_enable;
> +	bool px_needs_enable;
> +
> +	struct regmap *map;
> +};
> +
> +static IIO_CONST_ATTR(in_illuminance_scale_available,
> +		      "0.007629 0.061036 0.106813 0.473029");
> +
> +static struct attribute *pa12203001_attrs[] = {
> +	&iio_const_attr_in_illuminance_scale_available.dev_attr.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group pa12203001_attr_group = {
> +	.attrs = pa12203001_attrs,
> +};
> +
> +static const struct iio_chan_spec pa12203001_channels[] = {
> +	{
> +		.type = IIO_LIGHT,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SCALE),
> +	},
> +	{
> +		.type = IIO_PROXIMITY,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> +	}
> +};
> +
> +static const struct regmap_range pa12203001_volatile_regs_ranges[] = {
> +	regmap_reg_range(PA12203001_REG_ADL, PA12203001_REG_ADL + 1),
> +	regmap_reg_range(PA12203001_REG_PDH, PA12203001_REG_PDH),
> +};
> +
> +static const struct regmap_access_table pa12203001_volatile_regs = {
> +	.yes_ranges = pa12203001_volatile_regs_ranges,
> +	.n_yes_ranges = ARRAY_SIZE(pa12203001_volatile_regs_ranges),
> +};
> +
> +static const struct regmap_config pa12203001_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.max_register = PA12203001_REG_PSET,
> +	.cache_type = REGCACHE_RBTREE,
> +	.volatile_table = &pa12203001_volatile_regs,
> +};
> +
> +static inline int pa12203001_als_enable(struct pa12203001_data *data, u8 enable)
> +{
> +	int ret;
> +
> +	ret = regmap_update_bits(data->map, PA12203001_REG_CFG0,
> +				 PA12203001_ALS_EN_MASK, enable);
> +	if (ret < 0)
> +		return ret;
> +
> +	data->als_enabled = !!enable;
> +	return 0;
> +}
> +
> +static inline int pa12203001_px_enable(struct pa12203001_data *data, u8 enable)
> +{
> +	int ret;
> +
> +	ret = regmap_update_bits(data->map, PA12203001_REG_CFG0,
> +				 PA12203001_PX_EN_MASK, enable);
> +	if (ret < 0)
> +		return ret;
> +
> +	data->px_enabled = !!enable;
> +	return 0;
> +}
> +
> +static int pa12203001_set_power_state(struct pa12203001_data *data, bool on,
> +				      u8 mask)
> +{
> +#ifdef CONFIG_PM
> +	int ret;
> +
> +	mutex_lock(&data->lock);

If tests below are false, then we are holding the lock with no reason.

> +	if (on && (mask & PA12203001_ALS_EN_MASK)) {
> +		if (data->px_enabled) {
> +			ret = pa12203001_als_enable(data,
> +						    PA12203001_ALS_EN_MASK);
> +			if (ret < 0) {
> +				mutex_unlock(&data->lock);
> +				return ret;
> +			}

Use of `goto' would save two lines per exit point :)

> +		} else {
> +			data->als_needs_enable = true;
> +		}
> +	}
> +
> +	if (on && (mask & PA12203001_PX_EN_MASK)) {
> +		if (data->als_enabled) {
> +			ret = pa12203001_px_enable(data, PA12203001_PX_EN_MASK);
> +			if (ret < 0) {
> +				mutex_unlock(&data->lock);
> +				return ret;
> +			}
> +		} else {
> +			data->px_needs_enable = true;
> +		}
> +	}
> +	mutex_unlock(&data->lock);
> +
> +	if (on) {
> +		/* Get reference and resume */
> +		ret = pm_runtime_get_sync(&data->client->dev);
> +		if (ret < 0)
> +			pm_runtime_put_noidle(&data->client->dev);
> +
> +	} else {
> +		/*
> +		 * Turning off - restart timer, drop reference
> +		 * and setup autosuspend
> +		*/
> +		pm_runtime_mark_last_busy(&data->client->dev);
> +		ret = pm_runtime_put_autosuspend(&data->client->dev);
> +	}
> +	return ret;
> +
> +#endif
> +	return 0;
> +}
> +
> +static int pa12203001_read_raw(struct iio_dev *indio_dev,
> +			       struct iio_chan_spec const *chan, int *val,
> +			       int *val2, long mask)
> +{
> +	struct pa12203001_data *data = iio_priv(indio_dev);
> +	int ret;
> +	u8 dev_mask;
> +	unsigned int reg_byte;
> +	__le16 reg_word;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		switch (chan->type) {
> +		case IIO_LIGHT:
> +			dev_mask = PA12203001_ALS_EN_MASK;
> +			ret = pa12203001_set_power_state(data, true, dev_mask);
> +			if (ret < 0)
> +				return ret;
> +			/*
> +			 * ALS ADC value is stored in registers
> +			 * PA12203001_REG_ADL and in PA12203001_REG_ADL + 1.
> +			 */
> +			ret = regmap_bulk_read(data->map, PA12203001_REG_ADL,
> +					       &reg_word, 2);
> +			if (ret < 0)
> +				return ret;
> +			*val = le16_to_cpu(reg_word);
> +			ret = pa12203001_set_power_state(data, false, dev_mask);
> +			if (ret < 0)
> +				return ret;
> +			break;
> +		case IIO_PROXIMITY:
> +			dev_mask = PA12203001_PX_EN_MASK;
> +			ret = pa12203001_set_power_state(data, true, dev_mask);
> +			if (ret < 0)
> +				return ret;
> +			ret = regmap_read(data->map, PA12203001_REG_PDH,
> +					  &reg_byte);
> +			if (ret < 0)
> +				return ret;
> +			*val = reg_byte;
> +			ret = pa12203001_set_power_state(data, false, dev_mask);
> +			if (ret < 0)
> +				return ret;
> +			break;
> +		default:
> +			ret = -EINVAL;
> +			break;
> +		}
> +
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		ret = regmap_read(data->map, PA12203001_REG_CFG0, &reg_byte);
> +		if (ret < 0)
> +			return ret;
> +		*val = 0;
> +		reg_byte = (reg_byte & PA12203001_AFSR_MASK);
> +		*val2 = pa12203001_scales[reg_byte >> 4];
> +		return IIO_VAL_INT_PLUS_MICRO;
> +	default:
> +		break;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int pa12203001_write_raw(struct iio_dev *indio_dev,
> +				struct iio_chan_spec const *chan, int val,
> +				int val2, long mask)
> +{
> +	struct pa12203001_data *data = iio_priv(indio_dev);
> +	int i, ret;
> +	unsigned int reg_byte;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE:
> +		ret = regmap_read(data->map, PA12203001_REG_CFG0, &reg_byte);
> +		if (val != 0 || ret < 0)
> +			return -EINVAL;
> +		for (i = 0; i < ARRAY_SIZE(pa12203001_scales); i++) {
> +			if (val2 == pa12203001_scales[i])
> +				return regmap_update_bits(data->map,
> +							  PA12203001_REG_CFG0,
> +							  PA12203001_AFSR_MASK,
> +							  (i << 4));
> +		}
> +	break;

default case?

> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info pa12203001_info = {
> +	.driver_module	= THIS_MODULE,
> +	.read_raw = pa12203001_read_raw,
> +	.write_raw = pa12203001_write_raw,
> +	.attrs = &pa12203001_attr_group,
> +};
> +
> +static int pa12203001_init(struct iio_dev *indio_dev)
> +{
> +	struct pa12203001_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	ret = regmap_write(data->map, PA12203001_REG_CFG0,
> +			   PA12203001_REG_CFG0_DEFAULT);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_write(data->map, PA12203001_REG_CFG1,
> +			   PA12203001_REG_CFG1_DEFAULT);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_write(data->map, PA12203001_REG_CFG2,
> +			   PA12203001_REG_CFG2_DEFAULT);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_write(data->map, PA12203001_REG_CFG3,
> +			   PA12203001_REG_CFG3_DEFAULT);
> +	if (ret < 0)
> +		return ret;
> +
> +	return regmap_write(data->map, PA12203001_REG_PSET,
> +			    PA12203001_PSCAN);
> +}

Is the following acceptable?

	struct {
		u8 reg;
		u8 val;
	} regvals[] = { { PA12203001_REG_CFG, PA12203001_REG_CFG0_DEFAULT }, ... }; 

	int i, ret;

	for (i = 0; i < ARRAY_SIZE(regvals); i++) {
		ret = regmap_write(data->map, regvals[i].reg, regvals[i].val);
		if (ret < 0)
			return ret;
	}

	return 0;

> +
> +static int pa12203001_power_on(struct iio_dev *indio_dev)
> +{
> +	struct pa12203001_data *data = iio_priv(indio_dev);
> +	int ret;
> +	u8 enable = 0xff;
> +
> +	mutex_lock(&data->lock);
> +	ret = pa12203001_als_enable(data, enable);
> +	if (ret < 0) {
> +		mutex_unlock(&data->lock);
> +		return ret;
> +	}

goto is pretty conventional here (ch. 7 CodingStyle)

> +
> +	ret = pa12203001_px_enable(data, enable);
> +	if (ret < 0) {
> +		mutex_unlock(&data->lock);
> +		return ret;
> +	}
> +	mutex_unlock(&data->lock);
> +	return 0;
> +}
> +
> +static int pa12203001_power_off(struct iio_dev *indio_dev)
> +{
> +	struct pa12203001_data *data = iio_priv(indio_dev);
> +	int ret;
> +	u8 disable = 0x00;
> +
> +	mutex_lock(&data->lock);
> +	ret = pa12203001_als_enable(data, disable);
> +	if (ret < 0) {
> +		mutex_unlock(&data->lock);
> +		return ret;
> +	}
> +
> +	ret = pa12203001_px_enable(data, disable);
> +	if (ret < 0) {
> +		mutex_unlock(&data->lock);
> +		return ret;
> +	}
> +	mutex_unlock(&data->lock);
> +	return 0;
> +}

If I see it correctly, the only difference between power_on and
power_off functions is in one byte which is submitted to
{als,px}_enable(). Isn't it better to merge them in the third function
to reduce code duplication?

> +
> +static int pa12203001_probe(struct i2c_client *client,
> +			    const struct i2c_device_id *id)
> +{
> +	struct pa12203001_data *data;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev,
> +					  sizeof(struct pa12203001_data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	data = iio_priv(indio_dev);
> +	i2c_set_clientdata(client, indio_dev);
> +	data->client = client;
> +
> +	data->map = devm_regmap_init_i2c(client, &pa12203001_regmap_config);
> +	if (IS_ERR(data->map))
> +		return PTR_ERR(data->map);
> +
> +	mutex_init(&data->lock);
> +
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->info = &pa12203001_info;
> +	indio_dev->name = PA12203001_DRIVER_NAME;
> +	indio_dev->channels = pa12203001_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(pa12203001_channels);
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	ret = pa12203001_init(indio_dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = pa12203001_power_on(indio_dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = pm_runtime_set_active(&client->dev);
> +	if (ret < 0) {
> +		pa12203001_power_off(indio_dev);
> +		return ret;
> +	}
> +
> +	pm_runtime_enable(&client->dev);
> +	pm_runtime_set_autosuspend_delay(&client->dev,
> +					 PA12203001_SLEEP_DELAY_MS);
> +	pm_runtime_use_autosuspend(&client->dev);
> +
> +	return devm_iio_device_register(&client->dev, indio_dev);
> +}
> +
> +static int pa12203001_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);

We use additional var in this function to store device pointer, but do
not use it in suspend(), resume() etc where more complicated
constructions are used. Just for consistency :)

> +
> +	pm_runtime_disable(&client->dev);
> +	pm_runtime_set_suspended(&client->dev);
> +
> +	return pa12203001_power_off(indio_dev);
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int pa12203001_suspend(struct device *dev)
> +{
> +	return pa12203001_power_off(i2c_get_clientdata(to_i2c_client(dev)));
> +}
> +
> +static int pa12203001_resume(struct device *dev)
> +{
> +	return pa12203001_power_on(i2c_get_clientdata(to_i2c_client(dev)));
> +}
> +#endif
> +
> +#ifdef CONFIG_PM
> +static int pa12203001_runtime_suspend(struct device *dev)
> +{
> +	return pa12203001_power_off(i2c_get_clientdata(to_i2c_client(dev)));
> +}
> +
> +static int pa12203001_runtime_resume(struct device *dev)
> +{
> +	struct pa12203001_data *data;
> +
> +	data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
> +
> +	mutex_lock(&data->lock);
> +	if (data->als_needs_enable) {
> +		pa12203001_als_enable(data, PA12203001_ALS_EN_MASK);
> +		data->als_needs_enable = false;
> +	}
> +	if (data->px_needs_enable) {
> +		pa12203001_px_enable(data, PA12203001_PX_EN_MASK);
> +		data->px_needs_enable = false;
> +	}
> +	mutex_unlock(&data->lock);
> +	return 0;
> +}
> +#endif
> +
> +static const struct dev_pm_ops pa12203001_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(pa12203001_suspend, pa12203001_resume)
> +	SET_RUNTIME_PM_OPS(pa12203001_runtime_suspend,
> +			   pa12203001_runtime_resume, NULL)
> +};
> +
> +static const struct acpi_device_id pa12203001_acpi_match[] = {
> +	{ "TXCPA122", 0},
> +	{}
> +};
> +
> +MODULE_DEVICE_TABLE(acpi, pa12203001_acpi_match);
> +
> +static const struct i2c_device_id pa12203001_id[] = {
> +		{"txcpa122", 0},
> +		{}
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, pa12203001_id);
> +
> +static struct i2c_driver pa12203001_driver = {
> +	.driver = {
> +		.name = PA12203001_DRIVER_NAME,
> +		.pm = &pa12203001_pm_ops,
> +		.acpi_match_table = ACPI_PTR(pa12203001_acpi_match),
> +	},
> +	.probe = pa12203001_probe,
> +	.remove = pa12203001_remove,
> +	.id_table = pa12203001_id,
> +
> +};
> +module_i2c_driver(pa12203001_driver);
> +
> +MODULE_AUTHOR("Adriana Reus <adriana.reus@...el.com>");
> +MODULE_DESCRIPTION("Driver for TXC PA12203001 Proximity and Light Sensor");
> +MODULE_LICENSE("GPL v2");
> -- 
> 1.9.1
> 
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