Message-ID: <55CF4C4D.9080207@kernel.org>
Date:	Sat, 15 Aug 2015 15:27:25 +0100
From:	Jonathan Cameron <jic23@...nel.org>
To:	Adriana Reus <adriana.reus@...el.com>, pmeerw@...erw.net,
	daniel.baluta@...el.com
Cc:	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org
Subject: Re: [PATCH v3 1/2] iio: light: Add support for UPISEMI uS5182d als
 and proximity sensor

On 14/08/15 10:29, Adriana Reus wrote:
> Add support for UPISEMI us5182d als and proximity sensor.
> Supports raw readings.
> Data sheet for this device can be found here:
> http://www.upi-semi.com/temp/uS5182D-DS-P0103-temp.pdf
> 
> Signed-off-by: Adriana Reus <adriana.reus@...el.com>
Mostly looking pretty good.  I've partly been (slightly) pickier than normal
here because we are stalled for a few weeks anyway by the fact the merge
window for IIO is now probably done (about a week before Linus opens his)
and also we have device tree docs that will need comments or to sit for
quite a while on the mailing list.

Thanks,

Jonathan
> ---
> Changes since v2:
>  - Adressed Peter's comments (with the exception of setting
>    the ths_vals array as const - if I do that the compiler will
>    eventually whine because it gets passed as an argument to device_property_read).
That should be a giveaway that you want to have a copy rather than one
instance of this.  Stick a copy in your data structure with defaults
if no others are supplied.

Note we might have two different instances of this part on one device
with different thresholds...


>  - Tried to break down the compound register values into more intuitive definitions.
Much improved .
>  - Eliminated the read helper functions.
> 
>  drivers/iio/light/Kconfig   |  10 +
>  drivers/iio/light/Makefile  |   1 +
>  drivers/iio/light/us5182d.c | 484 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 495 insertions(+)
>  create mode 100644 drivers/iio/light/us5182d.c
> 
> diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
> index 7ed859a..0442f01 100644
> --- a/drivers/iio/light/Kconfig
> +++ b/drivers/iio/light/Kconfig
> @@ -287,6 +287,16 @@ config TSL4531
>  	 To compile this driver as a module, choose M here: the
>  	 module will be called tsl4531.
>  
> +config US5182D
> +	tristate "UPISEMI light and proximity sensor"
> +	depends on I2C
> +	help
> +	 If you say yes here you get support for the UPISEMI US5182D
> +	 ambient light and proximity sensor.
> +
> +	 This driver can also be built as a module.  If so, the module
> +	 will be called us5182d.
> +
>  config VCNL4000
>  	tristate "VCNL4000 combined ALS and proximity sensor"
>  	depends on I2C
> diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
> index 91c74c0..528cc8f 100644
> --- a/drivers/iio/light/Makefile
> +++ b/drivers/iio/light/Makefile
> @@ -27,4 +27,5 @@ obj-$(CONFIG_STK3310)          += stk3310.o
>  obj-$(CONFIG_TCS3414)		+= tcs3414.o
>  obj-$(CONFIG_TCS3472)		+= tcs3472.o
>  obj-$(CONFIG_TSL4531)		+= tsl4531.o
> +obj-$(CONFIG_US5182D)		+= us5182d.o
>  obj-$(CONFIG_VCNL4000)		+= vcnl4000.o
> diff --git a/drivers/iio/light/us5182d.c b/drivers/iio/light/us5182d.c
> new file mode 100644
> index 0000000..9ba99f5
> --- /dev/null
> +++ b/drivers/iio/light/us5182d.c
> @@ -0,0 +1,484 @@
> +/*
> + * Copyright (c) 2015 Intel Corporation
> + *
> + * Driver for UPISEMI us5182d 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.
> + *
> + * This program is distributed in the hope 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.
> + *
> + * 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>
> +
> +#define US5182D_REG_CFG0				0x00
> +#define US5182D_REG_CFG1				0x01
> +#define US5182D_REG_CFG2				0x02
> +#define US5182D_REG_CFG3				0x03
> +#define US5182D_REG_CFG4				0x10
> +
> +/*
> + * Registers for tuning the auto dark current cancelling feature.
> + * DARK_TH(reg 0x27,0x28) - threshold (counts) for auto dark cancelling.
> + * when ALS  > DARK_TH --> ALS_Code = ALS - Upper(0x2A) * Dark
> + * when ALS < DARK_TH --> ALS_Code = ALS - Lower(0x29) * Dark
> + */
> +#define US5182D_REG_UDARK_TH			0x27
> +#define US5182D_REG_DARK_AUTO_EN		0x2b
> +#define US5182D_REG_AUTO_LDARK_GAIN		0x29
> +#define US5182D_REG_AUTO_HDARK_GAIN		0x2a
> +
I'd be tempted to name these to make it clear which reg
they are in.
US5182D_CFG0_ONESHOT_EN etc.
Hartmut did a nice tidy up of another driver the other day.
He pulled the register address and elements down into one
place and used a it of indenting to make it easy to read.

For example.

#define US5182D_REG_CFG0				0x00
#define   US5182D_CFG0_ONESHOT_EN			BIT(6)
#define   US5182D_SHUTDOWN_EN				BIT(7)

etc.  Just a suggestion!  I don't really care as long as it
is clear what the register map is!

> +#define US5182D_ONESHOT_EN			BIT(6)
> +#define US5182D_SHUTDOWN_EN			BIT(7)
> +#define US5182D_OPMODE_ALS			0x01
> +#define US5182D_OPMODE_PX			0x02
> +#define US5182D_OPMODE_SHIFT			4
> +#define US5182D_WORD_ENABLE			BIT(0)
> +#define US5182D_ALS_RES16			BIT(4)
> +#define US5182D_PX_RES16			BIT(4)
> +#define US5182D_PXGAIN_DEFAULT			BIT(2)
> +#define US5182D_LED_CURRENT100			(BIT(4) | BIT(5))
> +
> +#define US5182D_REG_CFG0_DEFAULT \
> +	(US5182D_SHUTDOWN_EN | US5182D_WORD_ENABLE)
I'm missing something here, but SHUTDOWN_EN is never disabled?
I'd have assumed that meant the device was always off!

Guessing some magic is going on that might want a comment here.
(just read datasheet section on this so I now understand what you
 how this works, but please add a brief explanation, perhaps
 where you set the oneshot enable).

Also more I'd not bother having these defined like this
up here.  Doesn't add anything over using them directly
in the array below.

> +#define US5182D_REG_CFG1_DEFAULT		US5182D_ALS_RES16
> +#define US5182D_REG_CFG2_DEFAULT \
> +	(US5182D_PX_RES16 | US5182D_PXGAIN_DEFAULT)
> +#define US5182D_REG_CFG3_DEFAULT		US5182D_LED_CURRENT100
> +#define US5182D_REG_CFG4_DEFAULT		0x00
> +
> +#define US5182D_REG_DARK_AUTO_EN_DEFAULT	0x80
> +#define US5182D_REG_AUTO_LDARK_GAIN_DEFAULT	0x16
> +#define US5182D_REG_AUTO_HDARK_GAIN_DEFAULT	0x00
> +
> +#define US5182D_REG_ADL				0x0c
> +#define US5182D_REG_PDL				0x0e
> +
> +#define US5182D_REG_MODE_STORE			0x21
> +#define US5182D_STORE_MODE			0x01
> +
> +#define US5182D_REG_CHIPID			0xb2
> +
> +#define US5182D_OPMODE_MASK			GENMASK(5, 4)
> +#define US5182D_AGAIN_MASK			0x07
> +#define US5182D_RESET_CHIP			0x01
> +
> +#define US5182D_CHIPID				0x26
> +#define US5182D_DRV_NAME			"us5182d"
> +
> +#define US5182D_GA_RESOLUTION			1000
> +
> +#define US5182D_READ_BYTE			1
> +#define US5182D_READ_WORD			2
> +#define US5182D_OPSTORE_SLEEP_TIME		20 /* ms */
> +
> +/* available ranges: [12354, 7065, 3998, 2202, 1285, 498, 256, 138] lux */
> +static const int us5182d_scales[] = {188500, 107800, 61000, 33600, 19600, 7600,
> +				     3900, 2100};
> +
> +/*
> + * experimental th's that work with US5182D sensor on evaluation board
> + * roughly between 12-32 lux
Experimental (or I'll get a trivial batch within a day or so 'fixing' it ;)
Also long hand 'th' in the comment (thresholds persumably?).
> + */
> +static u16 us5182d_dark_ths_vals[] = {170, 200, 512, 512, 800, 2000, 4000,
> +				      8000};
> +
> +enum mode {
> +	US5182D_ALS_PX,
> +	US5182D_ALS_ONLY,
> +	US5182D_PX_ONLY
> +};
> +
> +struct us5182d_data {
> +	struct i2c_client *client;
> +	/* protect opmode */
Why not name it to indicate such?
> +	struct mutex lock;
> +
> +	/* Glass attenuation factor */
> +	u32 ga;
> +
> +	/* Dark gain tuning */
> +	u8 lower_dark_gain;
> +	u8 upper_dark_gain;
> +	u16 *us5182d_dark_ths;
> +
> +	u8 opmode;
> +};
> +
> +static IIO_CONST_ATTR(in_illuminance_scale_available,
> +		      "0.0021 0.0039 0.0076 0.0196 0.0336 0.061 0.1078 0.1885");
> +
> +static struct attribute *us5182d_attrs[] = {
> +	&iio_const_attr_in_illuminance_scale_available.dev_attr.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group us5182d_attr_group = {
> +	.attrs = us5182d_attrs,
> +};
> +
> +static const struct {
> +	u8 reg;
> +	u8 val;
> +} us5182d_regvals[] = {
> +	{US5182D_REG_CFG0, US5182D_REG_CFG0_DEFAULT},
> +	{US5182D_REG_CFG1, US5182D_REG_CFG1_DEFAULT},
> +	{US5182D_REG_CFG2, US5182D_REG_CFG2_DEFAULT},
> +	{US5182D_REG_CFG3, US5182D_REG_CFG3_DEFAULT},
> +	{US5182D_REG_MODE_STORE, US5182D_STORE_MODE},
> +	{US5182D_REG_CFG4, US5182D_REG_CFG4_DEFAULT},
> +};
> +
> +static const struct iio_chan_spec us5182d_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 int us5182d_get_als(struct us5182d_data *data)
> +{
> +	int ret;
> +	unsigned long result;
> +
> +	ret = i2c_smbus_read_word_data(data->client,
> +				       US5182D_REG_ADL);
> +	if (ret < 0)
> +		return ret;
> +
> +	result = ret * data->ga / US5182D_GA_RESOLUTION;
> +	if (result > 0xffff)
> +		result = 0xffff;
> +
> +	return result;
> +}
> +
> +static int us5182d_set_opmode(struct us5182d_data *data, u8 mode)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_read_byte_data(data->client, US5182D_REG_CFG0);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = ret | US5182D_ONESHOT_EN;
> +
> +	/* update mode */
> +	ret = ret & ~US5182D_OPMODE_MASK;
> +	ret = ret | (mode << US5182D_OPMODE_SHIFT);
> +
> +	ret = i2c_smbus_write_byte_data(data->client, US5182D_REG_CFG0, ret);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (mode == data->opmode)
> +		return 0;
> +
> +	data->opmode = mode;
> +	ret = i2c_smbus_write_byte_data(data->client, US5182D_REG_MODE_STORE,
> +					US5182D_STORE_MODE);
This is a lock / commit register? If so what is happening here is a little
bit quirky and a brief comment to explain would be good.

> +	if (ret < 0)
> +		return ret;
blank line here would make it a touch more readable (don't be afraid
to add white space in moderation!)
> +	msleep(US5182D_OPSTORE_SLEEP_TIME);
> +
> +	return 0;
> +}
> +
> +static int us5182d_read_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan, int *val,
> +			    int *val2, long mask)
> +{
> +	struct us5182d_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		switch (chan->type) {
> +		case IIO_LIGHT:
> +			mutex_lock(&data->lock);
> +			ret = us5182d_set_opmode(data, US5182D_OPMODE_ALS);
> +			if (ret < 0)
> +				goto out_err;
> +
> +			ret = us5182d_get_als(data);
> +			if (ret < 0)
> +				goto out_err;
> +			mutex_unlock(&data->lock);
> +			*val = ret;
> +			return IIO_VAL_INT;
> +		case IIO_PROXIMITY:
> +			mutex_lock(&data->lock);
> +			ret = us5182d_set_opmode(data, US5182D_OPMODE_PX);
> +			if (ret < 0)
> +				goto out_err;
> +
> +			ret = i2c_smbus_read_word_data(data->client,
> +						       US5182D_REG_PDL);
> +			if (ret < 0)
> +				goto out_err;
> +			mutex_unlock(&data->lock);
> +			*val = ret;
> +			return  IIO_VAL_INT;
> +		default:
> +			return -EINVAL;
> +		}
> +
> +	case IIO_CHAN_INFO_SCALE:
> +		ret = i2c_smbus_read_byte_data(data->client, US5182D_REG_CFG1);
> +		if (ret < 0)
> +			return ret;
I'd add a blank line here to aid readability (nitpick)
> +		*val = 0;
> +		ret = (ret & US5182D_AGAIN_MASK);
> +		*val2 = us5182d_scales[ret];
Maybe roll the two lines above into one?
Blank line here also nice for readability and in equivalent places.
> +		return IIO_VAL_INT_PLUS_MICRO;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return -EINVAL;
> +out_err:
> +	mutex_unlock(&data->lock);
> +	return ret;
> +}
> +
> +static int us5182d_update_dark_th(struct us5182d_data *data, int index)
> +{
> +	__be16 dark_th = cpu_to_be16(data->us5182d_dark_ths[index]);
> +	u8 *bytes = (u8 *)&dark_th;
Cast it at use site rather than here.

> +	int ret;
> +
> +	/* Registers Dark_Th (0x27 0x28) don't work in word mode accessing */
> +	ret = i2c_smbus_write_byte_data(data->client, US5182D_REG_UDARK_TH,
> +					bytes[0]);
> +	if (ret < 0)
> +		return ret;
> +
> +	return i2c_smbus_write_byte_data(data->client, US5182D_REG_UDARK_TH + 1,
> +					bytes[1]);
> +}
> +
> +static int us5182d_apply_scale(struct us5182d_data *data, int index)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_read_byte_data(data->client, US5182D_REG_CFG1);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = ret & (~US5182D_AGAIN_MASK);
> +	ret |= index;
> +
> +	ret = i2c_smbus_write_byte_data(data->client, US5182D_REG_CFG1, ret);
> +	if (ret < 0)
> +		return ret;
> +
> +	return us5182d_update_dark_th(data, index);
> +}
> +
> +static int us5182d_write_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan, int val,
> +			     int val2, long mask)
> +{
> +	struct us5182d_data *data = iio_priv(indio_dev);
> +	int ret, i;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE:
> +		if (val != 0)
> +			return -EINVAL;
> +		for (i = 0; i < ARRAY_SIZE(us5182d_scales); i++)
> +			if (val2 == us5182d_scales[i]) {
> +				mutex_lock(&data->lock);
> +				ret = us5182d_apply_scale(data, i);

I'd be tempted to move the lock into apply_scale... Otherwise, you
should add kernel-doc to that function to specify the lock should be held.
(I think given the calls out to update_dark_th in there, I'd be tempted
to just document the need for both those funcs to be called with the
lock held).
> +				mutex_unlock(&data->lock);
> +				return ret;
> +			}
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info us5182d_info = {
> +	.driver_module	= THIS_MODULE,
> +	.read_raw = us5182d_read_raw,
> +	.write_raw = us5182d_write_raw,
> +	.attrs = &us5182d_attr_group,
> +};
> +
> +static int us5182d_reset(struct iio_dev *indio_dev)
> +{
> +	struct us5182d_data *data = iio_priv(indio_dev);
> +
> +	return i2c_smbus_write_byte_data(data->client, US5182D_REG_CFG3,
> +					 US5182D_RESET_CHIP);
> +}
> +
> +static int us5182d_init(struct iio_dev *indio_dev)
> +{
> +	struct us5182d_data *data = iio_priv(indio_dev);
> +	int i, ret;
> +
> +	ret = us5182d_reset(indio_dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	data->opmode = 0;
> +	for (i = 0; i < ARRAY_SIZE(us5182d_regvals); i++) {
> +		ret = i2c_smbus_write_byte_data(data->client,
> +						us5182d_regvals[i].reg,
> +						us5182d_regvals[i].val);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void us5182d_get_platform_data(struct iio_dev *indio_dev)
> +{
> +	struct us5182d_data *data = iio_priv(indio_dev);
> +
> +	if (device_property_read_u32(&data->client->dev, "upisemi,glass-coef",
> +				     &data->ga))
> +		data->ga = US5182D_GA_RESOLUTION;
> +	if (device_property_read_u16_array(&data->client->dev,
> +					   "upisemi,dark-ths",
> +					   data->us5182d_dark_ths,
> +					   ARRAY_SIZE(us5182d_dark_ths_vals)))
> +		data->us5182d_dark_ths = us5182d_dark_ths_vals;
> +	if (device_property_read_u8(&data->client->dev,
> +				    "upisemi,upper-dark-gain",
> +				    &data->upper_dark_gain))
> +		data->upper_dark_gain = US5182D_REG_AUTO_HDARK_GAIN_DEFAULT;
> +	if (device_property_read_u8(&data->client->dev,
> +				    "upisemi,lower-dark-gain",
> +				    &data->lower_dark_gain))
> +		data->lower_dark_gain = US5182D_REG_AUTO_LDARK_GAIN_DEFAULT;
> +}
> +
> +static int  us5182d_dark_gain_config(struct iio_dev *indio_dev)
> +{
> +	struct us5182d_data *data = iio_priv(indio_dev);
> +	u8 index = US5182D_REG_CFG1_DEFAULT & US5182D_AGAIN_MASK;
> +	int ret;
> +
> +	ret = us5182d_update_dark_th(data, index);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = i2c_smbus_write_byte_data(data->client,
> +					US5182D_REG_AUTO_LDARK_GAIN,
> +					data->lower_dark_gain);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = i2c_smbus_write_byte_data(data->client,
> +					US5182D_REG_AUTO_HDARK_GAIN,
> +					data->upper_dark_gain);
> +	if (ret < 0)
> +		return ret;
> +
> +	return i2c_smbus_write_byte_data(data->client, US5182D_REG_DARK_AUTO_EN,
> +					 US5182D_REG_DARK_AUTO_EN_DEFAULT);
> +}
> +
> +static int us5182d_probe(struct i2c_client *client,
> +			 const struct i2c_device_id *id)
> +{
> +	struct us5182d_data *data;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	data = iio_priv(indio_dev);
> +	i2c_set_clientdata(client, indio_dev);
> +	data->client = client;
> +
> +	mutex_init(&data->lock);
> +
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->info = &us5182d_info;
> +	indio_dev->name = US5182D_DRV_NAME;
> +	indio_dev->channels = us5182d_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(us5182d_channels);
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	ret = i2c_smbus_read_byte_data(data->client, US5182D_REG_CHIPID);
> +	if (ret != US5182D_CHIPID) {
> +		dev_err(&data->client->dev,
> +			"Failed to detect US5182 light chip\n");
> +		return (ret < 0) ? ret : -ENODEV;
> +	}
> +
> +	us5182d_get_platform_data(indio_dev);
> +	ret = us5182d_init(indio_dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = us5182d_dark_gain_config(indio_dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	return iio_device_register(indio_dev);
> +}
> +
> +static int us5182d_remove(struct i2c_client *client)
> +{
> +	iio_device_unregister(i2c_get_clientdata(client));
> +	return i2c_smbus_write_byte_data(client, US5182D_REG_CFG0,
> +					 US5182D_REG_CFG0_DEFAULT);
Nitpick :)
I'd be tempted here (as we are shutting down and it doesn't matter anyway)
to use just the SHUTDOWN_EN value as then it's immediately obvious
what you are doing here.

> +}
> +
> +static const struct acpi_device_id us5182d_acpi_match[] = {
> +	{ "USD5182", 0},
> +	{}
> +};
> +
> +MODULE_DEVICE_TABLE(acpi, us5182d_acpi_match);
> +
> +static const struct i2c_device_id us5182d_id[] = {
> +		{"usd5182", 0},
> +		{}
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, us5182d_id);
> +
> +static struct i2c_driver us5182d_driver = {
> +	.driver = {
> +		.name = US5182D_DRV_NAME,
> +		.acpi_match_table = ACPI_PTR(us5182d_acpi_match),
> +	},
> +	.probe = us5182d_probe,
> +	.remove = us5182d_remove,
> +	.id_table = us5182d_id,
> +
> +};
> +module_i2c_driver(us5182d_driver);
> +
> +MODULE_AUTHOR("Adriana Reus <adriana.reus@...el.com>");
> +MODULE_DESCRIPTION("Driver for us5182d Proximity and Light Sensor");
> +MODULE_LICENSE("GPL v2");
> 

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