Linux driver for MAX517/518/519
Jonathan Cameron
jic23 at cam.ac.uk
Tue Jan 11 19:34:47 UTC 2011
On 01/11/11 16:20, Roland Stigge wrote:
> Hi,
>
> On 01/09/2011 11:31 PM, Jonathan Cameron wrote:
>> Pretty clean and nice driver so it was an easy review and should
>> be trivial to fix up for a merge.
>
> Thanks for your review!
>
> I'm attaching my update. Some notes:
>
> * I used the attributes out1_* how I found it in the other DAC driver
> already available
Cool, except for the out12_raw which could easily be the 12th channel.
This has to be one of the two options suggested the other day.
May require some macro magic. IIRC the relevant macro would be.
IIO_DEVICE_ATTR_NAMED(out1and2_raw, out1&2_raw, S_IWUSR, ...
These sort of macros are probably too specific to want to put them
in the dac.h header so just keep it local to the driver. It will
however want to be documented sometime soon. Perhaps either you
or Michael could propose some suitable additions to sysfs-bus-iio-*
docs? If not I'll get to it at some point, but it may be a week or so.
> * suspend doesn't need the protective #ifdefs
> * As for other drivers, drivers/staging/iio/dac/max517.h needs to go to
> include/linux/iio as soon as available
Sure.
>
> I think I addressed everything from your notes. Let me know if there is
> still some blocker.
>
> Thanks in advance!
>
> Roland
>
Below ack is subject to fixing that one small interface issue.
Send a copy with that fixed on to Greg for merging. If you want
to do that as a separate follow up patch that would also be fine
with me.
> IIO Driver for Maxim MAX517, MAX518 and MAX519 DAC
>
> Signed-off-by: Roland Stigge <stigge at antcom.de>
Acked-by: Jonathan Cameron <jic23 at cam.ac.uk>
> diff --git a/drivers/staging/iio/Documentation/dac/max517 b/drivers/staging/iio/Documentation/dac/max517
> new file mode 100644
> index 0000000..e60ec2f
> --- /dev/null
> +++ b/drivers/staging/iio/Documentation/dac/max517
> @@ -0,0 +1,41 @@
> +Kernel driver max517
> +====================
> +
> +Supported chips:
> + * Maxim MAX517, MAX518, MAX519
> + Prefix: 'max517'
> + Datasheet: Publicly available at the Maxim website
> + http://www.maxim-ic.com/
> +
> +Author:
> + Roland Stigge <stigge at antcom.de>
> +
> +Description
> +-----------
> +
> +The Maxim MAX517/518/519 is an 8-bit DAC on the I2C bus. The following table
> +shows the different feature sets of the variants MAX517, MAX518 and MAX519:
> +
> +Feature MAX517 MAX518 MAX519
> +--------------------------------------------------------------------------
> +One output channel X
> +Two output channels X X
> +Simultaneous output updates X X
> +Supply voltage as reference X
> +Separate reference input X
> +Reference input for each DAC X
> +
> +Via the iio sysfs interface, there are three attributes available: out1_raw,
> +out2_raw and out12_raw. With out1_raw and out2_raw, the current output values
> +(0..255) of the DACs can be written to the device. out12_raw can be used to set
> +both output channel values simultaneously.
> +
> +With MAX517, only out1_raw is available.
> +
> +Via out1_scale (and where appropriate, out2_scale), the current scaling factor
> +in mV can be read.
> +
> +When the operating system goes to a power down state, the Power Down function
> +of the chip is activated, reducing the supply current to 4uA.
> +
> +On power-up, the device is in 0V-output state.
> diff --git a/drivers/staging/iio/dac/Kconfig b/drivers/staging/iio/dac/Kconfig
> index 9191bd2..2120904 100644
> --- a/drivers/staging/iio/dac/Kconfig
> +++ b/drivers/staging/iio/dac/Kconfig
> @@ -19,3 +19,13 @@ config AD5446
>
> To compile this driver as a module, choose M here: the
> module will be called ad5446.
> +
> +config MAX517
> + tristate "Maxim MAX517/518/519 DAC driver"
> + depends on I2C && EXPERIMENTAL
> + help
> + If you say yes here you get support for the Maxim chips MAX517,
> + MAX518 and MAX519 (I2C 8-Bit DACs with rail-to-rail outputs).
> +
> + This driver can also be built as a module. If so, the module
> + will be called max517.
> diff --git a/drivers/staging/iio/dac/Makefile b/drivers/staging/iio/dac/Makefile
> index 7cf331b..1197aef 100644
> --- a/drivers/staging/iio/dac/Makefile
> +++ b/drivers/staging/iio/dac/Makefile
> @@ -4,3 +4,4 @@
>
> obj-$(CONFIG_AD5624R_SPI) += ad5624r_spi.o
> obj-$(CONFIG_AD5446) += ad5446.o
> +obj-$(CONFIG_MAX517) += max517.o
> diff --git a/drivers/staging/iio/dac/max517.c b/drivers/staging/iio/dac/max517.c
> new file mode 100644
> index 0000000..5c57523
> --- /dev/null
> +++ b/drivers/staging/iio/dac/max517.c
> @@ -0,0 +1,294 @@
> +/*
> + * max517.c - Support for Maxim MAX517, MAX518 and MAX519
> + *
> + * Copyright (C) 2010, 2011 Roland Stigge <stigge at antcom.de>
> + *
> + * 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/slab.h>
> +#include <linux/jiffies.h>
> +#include <linux/i2c.h>
> +#include <linux/err.h>
> +
> +#include "../iio.h"
> +#include "dac.h"
> +
> +#include "max517.h"
> +
> +#define MAX517_DRV_NAME "max517"
> +
> +/* Commands */
> +#define COMMAND_CHANNEL0 0x00
> +#define COMMAND_CHANNEL1 0x01 /* for MAX518 and MAX519 */
> +#define COMMAND_PD 0x08 /* Power Down */
> +
> +enum max517_device_ids {
> + ID_MAX517,
> + ID_MAX518,
> + ID_MAX519,
> +};
> +
> +struct max517_data {
> + struct iio_dev *indio_dev;
> + unsigned short vref_mv[2];
> +};
> +
> +/*
> + * channel: bit 0: channel 1
> + * bit 1: channel 2
> + * (this way, it's possible to set both channels at once)
> + */
> +static ssize_t max517_set_value(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count, int channel)
> +{
> + struct i2c_client *client = to_i2c_client(dev);
> + u8 outbuf[4]; /* 1x or 2x command + value */
> + int outbuf_size = 0;
> + int res;
> + long val;
> +
> + res = strict_strtol(buf, 10, &val);
> +
> + if (res)
> + return res;
> +
> + if (val < 0 || val > 255)
> + return -EINVAL;
> +
> + if (channel & 1) {
> + outbuf[outbuf_size++] = COMMAND_CHANNEL0;
> + outbuf[outbuf_size++] = val;
> + }
> + if (channel & 2) {
> + outbuf[outbuf_size++] = COMMAND_CHANNEL1;
> + outbuf[outbuf_size++] = val;
> + }
> +
> + /*
> + * At this point, there are always 1 or 2 two-byte commands in
> + * outbuf. With 2 commands, the device can set two outputs
> + * simultaneously, latching the values upon the end of the I2C
> + * transfer.
> + */
> +
> + res = i2c_master_send(client, outbuf, outbuf_size);
> + if (res < 0)
> + return res;
> +
> + return count;
> +}
> +
> +static ssize_t max517_set_value_1(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + return max517_set_value(dev, attr, buf, count, 1);
> +}
> +static IIO_DEV_ATTR_OUT_RAW(1, max517_set_value_1, 0);
> +
> +static ssize_t max517_set_value_2(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + return max517_set_value(dev, attr, buf, count, 2);
> +}
> +static IIO_DEV_ATTR_OUT_RAW(2, max517_set_value_2, 1);
> +
> +static ssize_t max517_set_value_both(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + return max517_set_value(dev, attr, buf, count, 3);
> +}
> +static IIO_DEV_ATTR_OUT_RAW(12, max517_set_value_both, -1);
> +
> +static ssize_t max517_show_scale(struct device *dev,
> + struct device_attribute *attr,
> + char *buf, int channel)
> +{
> + struct iio_dev *dev_info = dev_get_drvdata(dev);
> + struct max517_data *data = iio_dev_get_devdata(dev_info);
> + /* Corresponds to Vref / 2^(bits) */
> + unsigned int scale_uv = (data->vref_mv[channel - 1] * 1000) >> 8;
> +
> + return sprintf(buf, "%d.%03d\n", scale_uv / 1000, scale_uv % 1000);
> +}
> +
> +static ssize_t max517_show_scale1(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + return max517_show_scale(dev, attr, buf, 1);
> +}
> +static IIO_DEVICE_ATTR(out1_scale, S_IRUGO, max517_show_scale1, NULL, 0);
> +
> +static ssize_t max517_show_scale2(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + return max517_show_scale(dev, attr, buf, 2);
> +}
> +static IIO_DEVICE_ATTR(out2_scale, S_IRUGO, max517_show_scale2, NULL, 0);
> +
> +/* On MAX517 variant, we have two outputs */
> +static struct attribute *max517_attributes[] = {
> + &iio_dev_attr_out1_raw.dev_attr.attr,
> + &iio_dev_attr_out1_scale.dev_attr.attr,
> + NULL
> +};
> +
> +static struct attribute_group max517_attribute_group = {
> + .attrs = max517_attributes,
> +};
> +
> +/* On MAX518 and MAX518 variant, we have two outputs */
> +static struct attribute *max518_attributes[] = {
> + &iio_dev_attr_out1_raw.dev_attr.attr,
> + &iio_dev_attr_out1_scale.dev_attr.attr,
> + &iio_dev_attr_out2_raw.dev_attr.attr,
> + &iio_dev_attr_out2_scale.dev_attr.attr,
> + &iio_dev_attr_out12_raw.dev_attr.attr,
> + NULL
> +};
> +
> +static struct attribute_group max518_attribute_group = {
> + .attrs = max518_attributes,
> +};
> +
> +static int max517_suspend(struct i2c_client *client, pm_message_t mesg)
> +{
> + u8 outbuf = COMMAND_PD;
> +
> + return i2c_master_send(client, &outbuf, 1);
> +}
> +
> +static int max517_resume(struct i2c_client *client)
> +{
> + u8 outbuf = 0;
> +
> + return i2c_master_send(client, &outbuf, 1);
> +}
> +
> +static int max517_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct max517_data *data;
> + struct max517_platform_data *platform_data = client->dev.platform_data;
> + int err;
> +
> + data = kzalloc(sizeof(struct max517_data), GFP_KERNEL);
> + if (!data) {
> + err = -ENOMEM;
> + goto exit;
> + }
> +
> + i2c_set_clientdata(client, data);
> +
> + data->indio_dev = iio_allocate_device();
> + if (data->indio_dev == NULL) {
> + err = -ENOMEM;
> + goto exit_free_data;
> + }
> +
> + /* establish that the iio_dev is a child of the i2c device */
> + data->indio_dev->dev.parent = &client->dev;
> +
> + /* reduced attribute set for MAX517 */
> + if (id->driver_data == ID_MAX517)
> + data->indio_dev->attrs = &max517_attribute_group;
> + else
> + data->indio_dev->attrs = &max518_attribute_group;
> + data->indio_dev->dev_data = (void *)(data);
> + data->indio_dev->driver_module = THIS_MODULE;
> + data->indio_dev->modes = INDIO_DIRECT_MODE;
> +
> + /*
> + * Reference voltage on MAX518 is 5V, else take vref_mv from
> + * platform_data
> + */
Could munge this into slightly neater/shorter form with
if (id->driver_data == ID_MAX518 || !platform_data) {
data->vref_mv[0] = data->vref_mv[1] = 5000; /* mV */
} else {
data->vref_mv[0] = platform_data->vref_mv[0];
data->vref_mv[1] = platform_data->vref_mv[1];
}
> + if (id->driver_data == ID_MAX518)
> + data->vref_mv[0] = data->vref_mv[1] = 5000; /* mV */
> + else
> + if (platform_data) {
> + data->vref_mv[0] = platform_data->vref_mv[0];
> + data->vref_mv[1] = platform_data->vref_mv[1];
> + } else /* 5V by default */
> + data->vref_mv[0] = data->vref_mv[1] = 5000;
> +
> + err = iio_device_register(data->indio_dev);
> + if (err)
> + goto exit_free_device;
> +
> + dev_info(&client->dev, "DAC registered\n");
> +
> + return 0;
> +
> +exit_free_device:
> + iio_free_device(data->indio_dev);
> +exit_free_data:
> + kfree(data);
> +exit:
> + return err;
> +}
> +
> +static int max517_remove(struct i2c_client *client)
> +{
> + struct max517_data *data = i2c_get_clientdata(client);
> +
> + iio_free_device(data->indio_dev);
> + kfree(data);
> +
> + return 0;
> +}
> +
> +static const struct i2c_device_id max517_id[] = {
> + { "max517", ID_MAX517 },
> + { "max518", ID_MAX518 },
> + { "max519", ID_MAX519 },
> + { }
> +};
> +MODULE_DEVICE_TABLE(i2c, max517_id);
> +
> +static struct i2c_driver max517_driver = {
> + .driver = {
> + .name = MAX517_DRV_NAME,
> + },
> + .probe = max517_probe,
> + .remove = max517_remove,
> + .suspend = max517_suspend,
> + .resume = max517_resume,
> + .id_table = max517_id,
> +};
> +
> +static int __init max517_init(void)
> +{
> + return i2c_add_driver(&max517_driver);
> +}
> +
> +static void __exit max517_exit(void)
> +{
> + i2c_del_driver(&max517_driver);
> +}
> +
> +MODULE_AUTHOR("Roland Stigge <stigge at antcom.de>");
> +MODULE_DESCRIPTION("MAX517/MAX518/MAX519 8-bit DAC");
> +MODULE_LICENSE("GPL");
> +
> +module_init(max517_init);
> +module_exit(max517_exit);
> diff --git a/drivers/staging/iio/dac/max517.h b/drivers/staging/iio/dac/max517.h
> new file mode 100644
> index 0000000..8106cf2
> --- /dev/null
> +++ b/drivers/staging/iio/dac/max517.h
> @@ -0,0 +1,19 @@
> +/*
> + * MAX517 DAC driver
> + *
> + * Copyright 2011 Roland Stigge <stigge at antcom.de>
> + *
> + * Licensed under the GPL-2 or later.
> + */
> +#ifndef IIO_DAC_MAX517_H_
> +#define IIO_DAC_MAX517_H_
> +
> +/*
> + * TODO: struct max517_platform_data needs to go into include/linux/iio
> + */
> +
> +struct max517_platform_data {
> + u16 vref_mv[2];
> +};
> +
> +#endif /* IIO_DAC_MAX517_H_ */
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