Date:	Fri, 25 Jul 2014 19:52:08 +0100
From:	Jonathan Cameron <jic23@...nel.org>
To:	Philippe Reynes <tremyfr@...oo.fr>, linux-iio@...r.kernel.org
CC:	linux-kernel@...r.kernel.org, armadeus-forum@...ts.sourceforge.net,
	devicetree@...r.kernel.org, julien.boibessot@...e.fr,
	pmeerw@...erw.net, borneo.antonio@...il.com
Subject: Re: [PATCH v2] iio: add support of the max5821

On 20/07/14 17:10, Philippe Reynes wrote:
> Signed-off-by: Philippe Reynes <tremyfr@...oo.fr>
> ---
>   .../devicetree/bindings/iio/dac/max5821.txt        |   14 +
>   drivers/iio/dac/Kconfig                            |    8 +
>   drivers/iio/dac/Makefile                           |    1 +
>   drivers/iio/dac/max5821.c                          |  404 ++++++++++++++++++++
>   4 files changed, 427 insertions(+), 0 deletions(-)
>   create mode 100644 Documentation/devicetree/bindings/iio/dac/max5821.txt
>   create mode 100644 drivers/iio/dac/max5821.c
>
> Changelog:
> v2: (thanks Peter Meerwald, Antonio Borneo and Jonathan Cameron for the feedback)
> - use devm_iio_device_register
These top two have clashed... See below.
> - use regulator
> - add locking when reading a register
> - use array instead of switch for dac command
> - use ARRAY_SIZE instead of hardcode num of channels
> - set name
> - some others little fix
> diff --git a/Documentation/devicetree/bindings/iio/dac/max5821.txt b/Documentation/devicetree/bindings/iio/dac/max5821.txt
> new file mode 100644
> index 0000000..54276ce
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/dac/max5821.txt
> @@ -0,0 +1,14 @@
> +Maxim max5821 DAC device driver
> +
> +Required properties:
> +	- compatible: Must be "maxim,max5821"
> +	- reg: Should contain the DAC I2C address
> +	- vref-supply: Phandle to the vref power supply
> +
> +Example:
> +
> +	max5821@38 {
> +		compatible = "maxim,max5821";
> +		reg = <0x38>;
> +		vref-supply = <&reg_max5821>;
> +	};
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index f378ca8..fd14a72 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -152,6 +152,14 @@ config MAX517
>   	  This driver can also be built as a module.  If so, the module
>   	  will be called max517.
>
> +config MAX5821
> +	tristate "Maxim MAX5821 DAC driver"
> +	depends on I2C
> +	depends on OF
> +	help
> +	  Say yes here to build support for Maxim MAX5821
> +	  10 bits DAC.
> +
>   config MCP4725
>   	tristate "MCP4725 DAC driver"
>   	depends on I2C
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index bb84ad6..82545c0 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -17,4 +17,5 @@ obj-$(CONFIG_AD5791) += ad5791.o
>   obj-$(CONFIG_AD5686) += ad5686.o
>   obj-$(CONFIG_AD7303) += ad7303.o
>   obj-$(CONFIG_MAX517) += max517.o
> +obj-$(CONFIG_MAX5821) += max5821.o
>   obj-$(CONFIG_MCP4725) += mcp4725.o
> diff --git a/drivers/iio/dac/max5821.c b/drivers/iio/dac/max5821.c
> new file mode 100644
> index 0000000..86dcf77
> --- /dev/null
> +++ b/drivers/iio/dac/max5821.c
> @@ -0,0 +1,404 @@
> + /*
> +  * iio/dac/max5821.c
> +  * Copyright (C) 2014 Philippe Reynes
> +  *
> +  * 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.
> +  */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/iio/iio.h>
> +#include <linux/regulator/consumer.h>
> +
> +#define MAX5821_MAX_DAC_CHANNELS		2
> +
> +/* command bytes */
> +#define MAX5821_LOAD_DAC_A_IN_REG_B		0x00
> +#define MAX5821_LOAD_DAC_B_IN_REG_A		0x10
> +#define MAX5821_EXTENDED_COMMAND_MODE		0xf0
> +#define MAX5821_READ_DAC_A_COMMAND		0xf1
> +#define MAX5821_READ_DAC_B_COMMAND		0xf2
> +
> +#define MAX5821_EXTENDED_POWER_UP		0x00
> +#define MAX5821_EXTENDED_POWER_DOWN_MODE0	0x01
> +#define MAX5821_EXTENDED_POWER_DOWN_MODE1	0x02
> +#define MAX5821_EXTENDED_POWER_DOWN_MODE2	0x03
> +#define MAX5821_EXTENDED_DAC_A			0x04
> +#define MAX5821_EXTENDED_DAC_B			0x08
> +
> +enum max5821_device_ids {
> +	ID_MAX5821,
> +};
> +
> +struct max5821_data {
> +	struct i2c_client	*client;
> +	struct regulator	*vref_reg;
> +	unsigned short		vref_mv;
> +	bool			powerdown[MAX5821_MAX_DAC_CHANNELS];
> +	u8			powerdown_mode[MAX5821_MAX_DAC_CHANNELS];
> +	struct mutex		lock;
> +};
> +
> +static const char * const max5821_powerdown_modes[] = {
> +	"three_state",
> +	"1kohm_to_gnd",
> +	"100kohm_to_gnd",
> +};
> +
> +enum {
> +	MAX5821_THREE_STATE,
> +	MAX5821_1KOHM_TO_GND,
> +	MAX5821_100KOHM_TO_GND
> +};
> +
> +static int max5821_get_powerdown_mode(struct iio_dev *indio_dev,
> +				      const struct iio_chan_spec *chan)
> +{
> +	struct max5821_data *st = iio_priv(indio_dev);
> +
> +	return st->powerdown_mode[chan->channel];
> +}
> +
> +static int max5821_set_powerdown_mode(struct iio_dev *indio_dev,
> +				      const struct iio_chan_spec *chan,
> +				      unsigned int mode)
> +{
> +	struct max5821_data *st = iio_priv(indio_dev);
> +
> +	st->powerdown_mode[chan->channel] = mode;
> +
> +	return 0;
> +}
> +
> +static const struct iio_enum max5821_powerdown_mode_enum = {
> +	.items = max5821_powerdown_modes,
> +	.num_items = ARRAY_SIZE(max5821_powerdown_modes),
> +	.get = max5821_get_powerdown_mode,
> +	.set = max5821_set_powerdown_mode,
> +};
> +
> +static ssize_t max5821_read_dac_powerdown(struct iio_dev *indio_dev,
> +					  uintptr_t private,
> +					  const struct iio_chan_spec *chan,
> +					  char *buf)
> +{
> +	struct max5821_data *st = iio_priv(indio_dev);
> +
> +	return sprintf(buf, "%d\n", st->powerdown[chan->channel]);
> +}
> +
> +static int max5821_sync_powerdown_mode(struct max5821_data *data,
> +				       const struct iio_chan_spec *chan)
> +{
> +	u8 outbuf[2];
> +
> +	outbuf[0] = MAX5821_EXTENDED_COMMAND_MODE;
> +
> +	if (chan->channel == 0)
> +		outbuf[1] = MAX5821_EXTENDED_DAC_A;
> +	else
> +		outbuf[1] = MAX5821_EXTENDED_DAC_B;
> +
> +	if (data->powerdown[chan->channel])
> +		outbuf[1] |= data->powerdown_mode[chan->channel] + 1;
> +	else
> +		outbuf[1] |= MAX5821_EXTENDED_POWER_UP;
> +
> +	return i2c_master_send(data->client, outbuf, 2);
> +}
> +
> +static ssize_t max5821_write_dac_powerdown(struct iio_dev *indio_dev,
> +					   uintptr_t private,
> +					   const struct iio_chan_spec *chan,
> +					   const char *buf, size_t len)
> +{
> +	struct max5821_data *data = iio_priv(indio_dev);
> +	bool powerdown;
> +	int ret;
> +
> +	ret = strtobool(buf, &powerdown);
> +	if (ret)
> +		return ret;
> +
> +	data->powerdown[chan->channel] = powerdown;
> +
> +	ret = max5821_sync_powerdown_mode(data, chan);
> +	if (ret < 0)
> +		return ret;
> +
> +	return len;
> +}
> +
> +static const struct iio_chan_spec_ext_info max5821_ext_info[] = {
> +	{
> +		.name = "powerdown",
> +		.read = max5821_read_dac_powerdown,
> +		.write = max5821_write_dac_powerdown,
> +		.shared = IIO_SEPARATE,
> +	},
> +	IIO_ENUM("powerdown_mode", IIO_SEPARATE, &max5821_powerdown_mode_enum),
> +	IIO_ENUM_AVAILABLE("powerdown_mode", &max5821_powerdown_mode_enum),
> +	{ },
> +};
> +
> +#define MAX5821_CHANNEL(chan) {					\
> +	.type = IIO_VOLTAGE,					\
> +	.indexed = 1,						\
> +	.output = 1,						\
> +	.channel = (chan),					\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
> +	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SCALE),	\
> +	.ext_info = max5821_ext_info,				\
> +}
> +
> +static const struct iio_chan_spec max5821_channels[] = {
> +	MAX5821_CHANNEL(0),
> +	MAX5821_CHANNEL(1)
> +};
> +
> +static const u8 max5821_read_dac_command[] = {
> +	MAX5821_READ_DAC_A_COMMAND,
> +	MAX5821_READ_DAC_B_COMMAND
> +};
> +
> +static const u8 max5821_load_dac_command[] = {
> +	MAX5821_LOAD_DAC_A_IN_REG_B,
> +	MAX5821_LOAD_DAC_B_IN_REG_A
> +};
> +
> +static int max5821_get_value(struct iio_dev *indio_dev,
> +			     int *val, int channel)
> +{
> +	struct max5821_data *data = iio_priv(indio_dev);
> +	struct i2c_client *client = data->client;
> +	u8 outbuf[1];
> +	u8 inbuf[2];
> +	int ret;
> +
> +	if ((channel != 0) && (channel != 1))
> +		return -EINVAL;
> +
> +	outbuf[0] = max5821_read_dac_command[channel];
> +
> +	mutex_lock(&data->lock);
> +
> +	ret = i2c_master_send(client, outbuf, 1);
> +	if (ret < 0) {
> +		mutex_unlock(&data->lock);
> +		return ret;
> +	} else if (ret != 1) {
> +		mutex_unlock(&data->lock);
> +		return -EIO;
> +	}
> +
> +	ret = i2c_master_recv(client, inbuf, 2);
> +	if (ret < 0) {
> +		mutex_unlock(&data->lock);
> +		return ret;
> +	} else if (ret != 2) {
> +		mutex_unlock(&data->lock);
> +		return -EIO;
> +	}
> +
> +	mutex_unlock(&data->lock);
> +
> +	*val = ((inbuf[0] & 0x0f) << 6) | (inbuf[1] >> 2);
> +
> +	return IIO_VAL_INT;
> +}
> +
> +static int max5821_set_value(struct iio_dev *indio_dev,
> +			     int val, int channel)
> +{
> +	struct max5821_data *data = iio_priv(indio_dev);
> +	struct i2c_client *client = data->client;
> +	u8 outbuf[2];
> +	int ret;
> +
> +	if ((val < 0) || (val > 1023))
> +		return -EINVAL;
> +
> +	if ((channel != 0) && (channel != 1))
> +		return -EINVAL;
> +
> +	outbuf[0] = max5821_load_dac_command[channel];
> +	outbuf[0] |= val >> 6;
> +	outbuf[1] = (val & 0x3f) << 2;
> +
> +	ret = i2c_master_send(client, outbuf, 2);
> +	if (ret < 0)
> +		return ret;
> +	else if (ret != 2)
> +		return -EIO;
> +	else
> +		return 0;
> +}
> +
> +static int max5821_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan,
> +			   int *val, int *val2, long mask)
> +{
> +	struct max5821_data *data = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		return max5821_get_value(indio_dev, val, chan->channel);
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = data->vref_mv;
> +		*val2 = 10;
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int max5821_write_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     int val, int val2, long mask)
> +{
> +	if (val2 != 0)
> +		return -EINVAL;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		return max5821_set_value(indio_dev, val, chan->channel);
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int max5821_suspend(struct device *dev)
> +{
> +	u8 outbuf[2] = { MAX5821_EXTENDED_COMMAND_MODE,
> +			 MAX5821_EXTENDED_DAC_A |
> +			 MAX5821_EXTENDED_DAC_B |
> +			 MAX5821_EXTENDED_POWER_DOWN_MODE2 };
> +
> +	return i2c_master_send(to_i2c_client(dev), outbuf, 2);
> +}
> +
> +static int max5821_resume(struct device *dev)
> +{
> +	u8 outbuf[2] = { MAX5821_EXTENDED_COMMAND_MODE,
> +			 MAX5821_EXTENDED_DAC_A |
> +			 MAX5821_EXTENDED_DAC_B |
> +			 MAX5821_EXTENDED_POWER_UP };
> +
> +	return i2c_master_send(to_i2c_client(dev), outbuf, 2);
> +}
> +
> +static SIMPLE_DEV_PM_OPS(max5821_pm_ops, max5821_suspend, max5821_resume);
> +#define MAX5821_PM_OPS (&max5821_pm_ops)
> +#else
> +#define MAX5821_PM_OPS NULL
> +#endif /* CONFIG_PM_SLEEP */
> +
> +static const struct iio_info max5821_info = {
> +	.read_raw = max5821_read_raw,
> +	.write_raw = max5821_write_raw,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static int max5821_probe(struct i2c_client *client,
> +			const struct i2c_device_id *id)
> +{
> +	struct max5821_data *data;
> +	struct iio_dev *indio_dev;
> +	u32 tmp;
> +	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);
> +
> +	/* max5821 start in powerdown mode 100Kohm to ground */
> +	for (tmp = 0; tmp < MAX5821_MAX_DAC_CHANNELS; tmp++) {
> +		data->powerdown[tmp] = true;
> +		data->powerdown_mode[tmp] = MAX5821_100KOHM_TO_GND;
> +	}
> +
> +	data->vref_reg = devm_regulator_get(&client->dev, "vref");
> +	if (IS_ERR(data->vref_reg)) {
> +		ret = PTR_ERR(data->vref_reg);
> +		dev_err(&client->dev,
> +			"Failed to get vref regulator: %d\n", ret);
> +		goto error_free_reg;
> +	}
> +
> +	ret = regulator_enable(data->vref_reg);
> +	if (ret) {
> +		dev_err(&client->dev,
> +			"Failed to enable vref regulator: %d\n", ret);
> +		goto error_free_reg;
> +	}
> +
> +	ret = regulator_get_voltage(data->vref_reg);
> +	if (ret < 0) {
> +		dev_err(&client->dev,
> +			"Failed to get voltage on regulator: %d\n", ret);
> +		goto error_disable_reg;
> +	}
> +
> +	data->vref_mv = ret / 1000;
> +
> +	indio_dev->name = id->name;
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->num_channels = ARRAY_SIZE(max5821_channels);
> +	indio_dev->channels = max5821_channels;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->info = &max5821_info;
> +
> +	return devm_iio_device_register(&client->dev, indio_dev);
> +
> +error_disable_reg:
> +	regulator_disable(data->vref_reg);
> +
> +error_free_reg:
> +
> +	return ret;
> +}
> +
> +static int max5821_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +	struct max5821_data *data = iio_priv(indio_dev);
> +
> +	regulator_disable(data->vref_reg);
Using devm register above means that it won't have been
unregistered before you turn off the regulator....

Hence unfortunately you need to go back to explicit calling
of iio_device_register/unregister.
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id max5821_id[] = {
> +	{ "max5821", ID_MAX5821 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, max5821_id);
> +
> +static const struct of_device_id max5821_of_match[] = {
> +	{ .compatible = "maxim,max5821" },
> +	{ }
> +};
> +
> +static struct i2c_driver max5821_driver = {
> +	.driver = {
> +		.name	= "max5821",
> +		.pm     = MAX5821_PM_OPS,
> +		.owner	= THIS_MODULE,
> +	},
> +	.probe		= max5821_probe,
> +	.remove		= max5821_remove,
> +	.id_table	= max5821_id,
> +};
> +module_i2c_driver(max5821_driver);
> +
> +MODULE_AUTHOR("Philippe Reynes <tremyfr@...oo.fr>");
> +MODULE_DESCRIPTION("MAX5821 DAC");
> +MODULE_LICENSE("GPL v2");
>

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