Message-id: <54858066.6080204@samsung.com>
Date:	Mon, 08 Dec 2014 11:41:42 +0100
From:	Karol Wrona <k.wrona@...sung.com>
To:	Jonathan Cameron <jic23@...nel.org>, linux-iio@...r.kernel.org,
	Hartmut Knaack <knaack.h@....de>, linux-kernel@...r.kernel.org
Cc:	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Karol Wrona <wrona.vy@...il.com>
Subject: Re: [PATCH v3 4/5] iio: common: ssp_sensors: Add sensorhub
 accelerometer sensor

On 12/06/2014 03:52 PM, Jonathan Cameron wrote:
> On 05/12/14 19:54, Karol Wrona wrote:
>> This patch adds accelerometer iio driver which uses sensorhub as data
>> provider.
>>
>> Change-Id: I4686741b7401ec5cbf4b5d0f2a5cc146fbe24d53
>> Signed-off-by: Karol Wrona <k.wrona@...sung.com>
>> Acked-by: Kyungmin Park <kyungmin.park@...sung.com>
>> ---
>>   drivers/iio/accel/Makefile           |    1 +
>>   drivers/iio/accel/ssp_accel_sensor.c |  203 ++++++++++++++++++++++++++++++++++
>>   2 files changed, 204 insertions(+)
>>   create mode 100644 drivers/iio/accel/ssp_accel_sensor.c
>>
>> diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
>> index a593996..df6a0b2 100644
>> --- a/drivers/iio/accel/Makefile
>> +++ b/drivers/iio/accel/Makefile
>> @@ -9,6 +9,7 @@ obj-$(CONFIG_HID_SENSOR_ACCEL_3D) += hid-sensor-accel-3d.o
>>   obj-$(CONFIG_KXCJK1013) += kxcjk-1013.o
>>   obj-$(CONFIG_KXSD9)	+= kxsd9.o
>>   obj-$(CONFIG_MMA8452)	+= mma8452.o
>> +obj-$(CONFIG_IIO_SSP_SENSOR) += ssp_accel_sensor.o
>>
>>   obj-$(CONFIG_IIO_ST_ACCEL_3AXIS) += st_accel.o
>>   st_accel-y := st_accel_core.o
>> diff --git a/drivers/iio/accel/ssp_accel_sensor.c b/drivers/iio/accel/ssp_accel_sensor.c
>> new file mode 100644
>> index 0000000..0a47c29
>> --- /dev/null
>> +++ b/drivers/iio/accel/ssp_accel_sensor.c
>> @@ -0,0 +1,203 @@
>> +/*
>> + *  Copyright (C) 2014, Samsung Electronics Co. Ltd. All Rights Reserved.
>> + *
>> + *  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; either version 2 of the License, or
>> + *  (at your option) any later version.
>> + *
>> + *  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/iio/common/ssp_sensors.h>
>> +#include <linux/iio/iio.h>
>> +#include <linux/iio/kfifo_buf.h>
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/slab.h>
>> +#include "../common/ssp_sensors/ssp_iio_sensor.h"
>> +
>> +#define SSP_CHANNEL_COUNT 3
>> +
>> +#define SSP_ACCEL_NAME "ssp-accelerometer"
>> +static const char ssp_accel_device_name[] = SSP_ACCEL_NAME;
>> +
>> +enum ssp_accel_3d_channel {
>> +	SSP_CHANNEL_SCAN_INDEX_X,
>> +	SSP_CHANNEL_SCAN_INDEX_Y,
>> +	SSP_CHANNEL_SCAN_INDEX_Z,
>> +	SSP_CHANNEL_SCAN_INDEX_TIME,
>> +	SSP_ACCEL_3D_CHANNEL_MAX,
> you don't actually use this max element so drop it.
>> +};
>> +
>> +static int ssp_accel_read_raw(struct iio_dev *indio_dev,
>> +			      struct iio_chan_spec const *chan,  int *val,
>> +			      int *val2, long mask)
>> +{
>> +	u32 t;
>> +	struct ssp_data *data = dev_get_drvdata(indio_dev->dev.parent->parent);
>> +
>> +	switch (mask) {
>> +	case IIO_CHAN_INFO_SAMP_FREQ:
>> +		t = ssp_get_sensor_delay(data, SSP_ACCELEROMETER_SENSOR);
>> +		ssp_convert_to_freq(t, val, val2);
>> +		return IIO_VAL_INT_PLUS_MICRO;
>> +	default:
>> +		break;
>> +	}
>> +
>> +	return -EINVAL;
>> +}
>> +
>> +static int ssp_accel_write_raw(struct iio_dev *indio_dev,
>> +			       struct iio_chan_spec const *chan, int val,
>> +			       int val2, long mask)
>> +{
>> +	int ret;
>> +	struct ssp_data *data = dev_get_drvdata(indio_dev->dev.parent->parent);
>> +
>> +	switch (mask) {
>> +	case IIO_CHAN_INFO_SAMP_FREQ:
>> +		ret = ssp_convert_to_time(val, val2);
>> +		ret = ssp_change_delay(data, SSP_ACCELEROMETER_SENSOR, ret);
>> +		if (ret < 0)
>> +			dev_err(&indio_dev->dev, "accel sensor enable fail\n");
>> +
>> +		return ret;
>> +	default:
>> +		break;
>> +	}
>> +
>> +	return -EINVAL;
>> +}
>> +
>> +static struct iio_info ssp_accel_iio_info = {
>> +	.read_raw = &ssp_accel_read_raw,
>> +	.write_raw = &ssp_accel_write_raw,
>> +};
>> +
>> +static const struct iio_chan_spec ssp_acc_channels[] = {
>> +	SSP_CHANNEL_AG(IIO_ACCEL, IIO_MOD_X, SSP_CHANNEL_SCAN_INDEX_X),
>> +	SSP_CHANNEL_AG(IIO_ACCEL, IIO_MOD_Y, SSP_CHANNEL_SCAN_INDEX_Y),
>> +	SSP_CHANNEL_AG(IIO_ACCEL, IIO_MOD_Z, SSP_CHANNEL_SCAN_INDEX_Z),
>> +	IIO_CHAN_SOFT_TIMESTAMP(SSP_CHANNEL_SCAN_INDEX_TIME),
> hmm. Not actually a soft timestamp so I guess we should really rename that
> macro.  Actually is your resulting timestamp 32 bit?  If so you could
> specify the channel as such and include a scale to allow userspace to
> convert it as it wishes.
Ok, I will rethink that.  This timestamp is 64-bit and it is system time
plus diff taken from sample but I would have relative time at all on 32-bit.
>> +};
>> +
>> +static int ssp_process_accel_data(struct iio_dev *indio_dev, void *buf,
>> +				  int64_t timestamp)
> We could hang a set of triggers of the parent device and use the in
> conjunction with some local buffering to fire off the children.
> There would be the advantage that we could trigger other sensors off them
> (to get roughly synchronized additional signals).  Probably not worth it
> though but I thought I'd mention the option.
>> +{
>> +	__le32 time;
>> +	const int len = SSP_ACCELEROMETER_SIZE;
>> +	int64_t calculated_time;
>> +	char *data;
>> +	int ret;
>> +
>> +	if (indio_dev->scan_bytes == 0)
>> +		return 0;
>> +
>> +	data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
>> +	if (!data)
>> +		return -ENOMEM;
> I'd allocate this in your iio_priv structure and setup the length in preenable
> etc.  Last thing we want in here is to waste time with a memory allocation and
> free.
You are right. Generally for commands in ssp_spi.c these allocation won't hurt 
but here I created a pure waste..
>> +
>> +	memcpy(data, buf, len);
> It's a little uggly but I think you can avoid the copy if the timestamp
> isn't in use (as then we don't need the additional space).
>> +
>> +	if (indio_dev->scan_timestamp) {
>> +		memcpy(&time, &((char *)buf)[len], SSP_TIME_SIZE);
>> +		calculated_time =
>> +			timestamp + (int64_t)le32_to_cpu(time) * 1000000;
> Cool - our first hardware supplied timestamp ;)
>> +	}
>> +
>> +	ret = iio_push_to_buffers_with_timestamp(indio_dev, data,
>> +						 calculated_time);
>> +
>> +	kfree(data);
>> +
>> +	return ret;
>> +}
>> +
>> +static const struct iio_buffer_setup_ops ssp_accel_buffer_ops = {
>> +	.postenable = &ssp_common_buffer_postenable,
>> +	.predisable = &ssp_common_buffer_predisable,
>> +};
>> +
>> +static int ssp_accel_probe(struct platform_device *pdev)
>> +{
>> +	int ret;
>> +	struct iio_dev *indio_dev;
>> +	struct ssp_sensor_data *spd;
>> +
>> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*spd));
>> +	if (!indio_dev)
>> +		return -ENOMEM;
>> +
>> +	spd = iio_priv(indio_dev);
>> +
>> +	spd->process_data = ssp_process_accel_data;
>> +	spd->type = SSP_ACCELEROMETER_SENSOR;
>> +
>> +	indio_dev->name = ssp_accel_device_name;
>> +	indio_dev->dev.parent = &pdev->dev;
>> +	indio_dev->dev.of_node = pdev->dev.of_node;
>> +	indio_dev->info = &ssp_accel_iio_info;
>> +	indio_dev->modes = INDIO_BUFFER_HARDWARE;
> hmm. A rare beast with no polled access.  But is it actually a hardware
> buffer?  Doesn't look that much like one.  I think we may need a more
> refined set of options for the buffer type.
Here I'm confused. Do you mean a new buffer type in IIO?
>
>> +	indio_dev->channels = ssp_acc_channels;
>> +	indio_dev->num_channels = ARRAY_SIZE(ssp_acc_channels);
>> +
>> +	ret = ssp_common_setup_buffer(indio_dev, &ssp_accel_buffer_ops);
>> +	if (ret < 0) {
>> +		dev_err(&pdev->dev, "Buffer setup fail\n");
>> +		return ret;
>> +	}
>> +
>> +	platform_set_drvdata(pdev, indio_dev);
>> +
>> +	ret = iio_device_register(indio_dev);
>> +	if (ret < 0) {
>> +		iio_buffer_unregister(indio_dev);
>> +		iio_kfifo_free(indio_dev->buffer);
>> +		return ret;
>> +	}
>> +
>> +	/* need to be really sure about success for this one */
> err, what does the comment mean?
this only adds ptr to the table so I wanted to assure that it should be done 
after ii_device_register, maybe this is too obvious to comment.
>> +	ssp_register_consumer(indio_dev, SSP_ACCELEROMETER_SENSOR);
>> +
>> +	return 0;
>> +}
>> +
>> +static int ssp_accel_remove(struct platform_device *pdev)
>> +{
>> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
>> +
>> +	iio_device_unregister(indio_dev);
>> +	iio_buffer_unregister(indio_dev);
>> +	iio_kfifo_free(indio_dev->buffer);
> Feels rather like we need a devm_iio_kfifo_alloc
> Actually, as you are wrapping the allocation, I'd prefer you have
> an obviously matched cleanup function to ssp_common_setup_buffer
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct of_device_id ssp_accel_id_table[] = {
>> +	{
>> +		.compatible = "samsung,mpu6500-accel",
>> +	},
>> +	{},
>> +};
>> +
>> +static struct platform_driver ssp_accel_driver = {
>> +	.driver = {
>> +		.owner = THIS_MODULE,
>> +		.name = SSP_ACCEL_NAME,
>> +		.of_match_table = ssp_accel_id_table,
>> +	},
>> +	.probe = ssp_accel_probe,
>> +	.remove =  ssp_accel_remove,
>> +};
>> +
>> +module_platform_driver(ssp_accel_driver);
>> +
>> +MODULE_AUTHOR("Karol Wrona <k.wrona@...sung.com>");
>> +MODULE_DESCRIPTION("Samsung sensorhub accelerometers driver");
>> +MODULE_LICENSE("GPL");
>>
>
>

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