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Subject: Re: [PATCH v5 4/7] hwmon: pmbus: adm1266: Add ioctl commands
To:     alexandru.tachici@analog.com, linux-hwmon@vger.kernel.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
Cc:     robh+dt@kernel.org
References: <20200624151736.95785-1-alexandru.tachici@analog.com>
 <20200624151736.95785-5-alexandru.tachici@analog.com>
From:   Guenter Roeck <linux@roeck-us.net>
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Message-ID: <bb1ea000-29d0-0eb0-818f-513aa33c400d@roeck-us.net>
Date:   Wed, 24 Jun 2020 08:36:11 -0700
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On 6/24/20 8:17 AM, alexandru.tachici@analog.com wrote:
> From: Alexandru Tachici <alexandru.tachici@analog.com>
> 
> Add two ioctl commands for reading the current state
> of the adm1266 sequencer and sending commands.
> 

Please note that I am not going to a accept any ioctls for hwmon drivers,
much less unprivileged commands like this.

Guenter

> Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
> ---
>  Documentation/hwmon/adm1266.rst               | 15 +++
>  .../userspace-api/ioctl/ioctl-number.rst      |  1 +
>  drivers/hwmon/pmbus/adm1266.c                 | 97 +++++++++++++++++++
>  include/uapi/linux/adm1266.h                  | 16 +++
>  4 files changed, 129 insertions(+)
>  create mode 100644 include/uapi/linux/adm1266.h
> 
> diff --git a/Documentation/hwmon/adm1266.rst b/Documentation/hwmon/adm1266.rst
> index 65662115750c..5dc05808db60 100644
> --- a/Documentation/hwmon/adm1266.rst
> +++ b/Documentation/hwmon/adm1266.rst
> @@ -33,3 +33,18 @@ inX_min			Minimum Voltage.
>  inX_max			Maximum voltage.
>  inX_min_alarm		Voltage low alarm.
>  inX_max_alarm		Voltage high alarm.
> +
> +
> +User API
> +========
> +
> +ioctls
> +------
> +
> +ADM1266_SET_GO_COMMAND:
> +
> +  Issue a GO_COMMAND to the device.
> +
> +ADM1266_GET_STATUS:
> +
> +  Returns state of the sequencer.
> diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
> index 59472cd6a11d..df92ca274622 100644
> --- a/Documentation/userspace-api/ioctl/ioctl-number.rst
> +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
> @@ -348,6 +348,7 @@ Code  Seq#    Include File                                           Comments
>  0xCC  00-0F  drivers/misc/ibmvmc.h                                   pseries VMC driver
>  0xCD  01     linux/reiserfs_fs.h
>  0xCF  02     fs/cifs/ioctl.c
> +0xD1  00-0F  linux/adm1266.h
>  0xDB  00-0F  drivers/char/mwave/mwavepub.h
>  0xDD  00-3F                                                          ZFCP device driver see drivers/s390/scsi/
>                                                                       <mailto:aherrman@de.ibm.com>
> diff --git a/drivers/hwmon/pmbus/adm1266.c b/drivers/hwmon/pmbus/adm1266.c
> index 76bf2c78e737..0960ead8d96a 100644
> --- a/drivers/hwmon/pmbus/adm1266.c
> +++ b/drivers/hwmon/pmbus/adm1266.c
> @@ -15,11 +15,16 @@
>  #include <linux/init.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> +#include <linux/proc_fs.h>
>  #include <linux/slab.h>
> +#include <linux/uaccess.h>
>  
> +#include <linux/adm1266.h>
>  #include "pmbus.h"
>  
>  #define ADM1266_PDIO_CONFIG	0xD4
> +#define ADM1266_GO_COMMAND	0xD8
> +#define ADM1266_READ_STATE	0xD9
>  #define ADM1266_GPIO_CONFIG	0xE1
>  #define ADM1266_PDIO_STATUS	0xE9
>  #define ADM1266_GPIO_STATUS	0xEA
> @@ -46,6 +51,7 @@ struct adm1266_data {
>  	struct gpio_chip gc;
>  	const char *gpio_names[ADM1266_GPIO_NR + ADM1266_PDIO_NR];
>  	struct i2c_client *client;
> +	struct mutex ioctl_mutex; /* lock ioctl access */
>  };
>  
>  /* Different from Block Read as it sends data and waits for the slave to
> @@ -311,6 +317,93 @@ static int adm1266_config_gpio(struct adm1266_data *data)
>  }
>  #endif
>  
> +static int adm1266_set_go_command_op(struct adm1266_data *data, u8 val)
> +{
> +	val = FIELD_GET(GENMASK(4, 0), val);
> +
> +	return i2c_smbus_write_word_data(data->client, ADM1266_GO_COMMAND, val);
> +}
> +
> +static int adm1266_ioctl_unlocked(struct file *fp, unsigned int cmd,
> +				  unsigned long arg)
> +{
> +	int __user *argp = (int __user *)arg;
> +	struct adm1266_data *data;
> +	int val;
> +	int ret;
> +
> +	data = fp->private_data;
> +
> +	if (!argp)
> +		return -EINVAL;
> +
> +	switch (cmd) {
> +	case ADM1266_SET_GO_COMMAND:
> +		if (copy_from_user(&val, argp, sizeof(int)))
> +			return -EFAULT;
> +
> +		return adm1266_set_go_command_op(data, val);
> +	case ADM1266_GET_STATUS:
> +		ret = i2c_smbus_read_word_data(data->client,
> +					       ADM1266_READ_STATE);
> +
> +		if (ret < 0)
> +			return ret;
> +
> +		if (copy_to_user(argp, &ret, sizeof(int)))
> +			return -EFAULT;
> +
> +		break;
> +	default:
> +		return -ENOTTY;
> +	}
> +
> +	return 0;
> +}
> +
> +static long adm1266_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
> +{
> +	struct adm1266_data *data;
> +	long ret;
> +
> +	data = fp->private_data;
> +
> +	mutex_lock(&data->ioctl_mutex);
> +	ret = adm1266_ioctl_unlocked(fp, cmd, arg);
> +	mutex_unlock(&data->ioctl_mutex);
> +
> +	return ret;
> +}
> +
> +static int adm1266_open(struct inode *inode, struct file *filp)
> +{
> +	filp->private_data = PDE_DATA(inode);
> +
> +	return 0;
> +}
> +
> +static const struct proc_ops adm1266_proc_ops = {
> +	.proc_open	= adm1266_open,
> +	.proc_ioctl	= adm1266_ioctl,
> +};
> +
> +static int adm1266_init_procfs(struct adm1266_data *data)
> +{
> +	struct proc_dir_entry *proc_dir;
> +	u8 proc_fs_name[32];
> +
> +	mutex_init(&data->ioctl_mutex);
> +
> +	snprintf(proc_fs_name, 32, "adm1266-%x", data->client->addr);
> +	proc_dir = proc_create_data(proc_fs_name, 0, NULL, &adm1266_proc_ops,
> +				    data);
> +
> +	if (!proc_dir)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
>  static int adm1266_probe(struct i2c_client *client,
>  			 const struct i2c_device_id *id)
>  {
> @@ -333,6 +426,10 @@ static int adm1266_probe(struct i2c_client *client,
>  
>  	crc8_populate_msb(pmbus_crc_table, 0x7);
>  
> +	ret = adm1266_init_procfs(data);
> +	if (ret < 0)
> +		return ret;
> +
>  	info = &data->info;
>  	info->pages = 17;
>  	info->format[PSC_VOLTAGE_OUT] = linear;
> diff --git a/include/uapi/linux/adm1266.h b/include/uapi/linux/adm1266.h
> new file mode 100644
> index 000000000000..535d270ee8c5
> --- /dev/null
> +++ b/include/uapi/linux/adm1266.h
> @@ -0,0 +1,16 @@
> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> +/*
> + * ADM1266 - Cascadable Super Sequencer with Margin
> + * Control and Fault Recording
> + *
> + * Copyright 2020 Analog Devices Inc.
> + */
> +
> +#ifndef _LINUX_ADM1266_H
> +#define _LINUX_ADM1266_H
> +
> +/* ADM1266 ioctl commands */
> +#define ADM1266_SET_GO_COMMAND		_IOW(0xD1, 0x00, int)
> +#define ADM1266_GET_STATUS		_IOR(0xD1, 0x01, int)
> +
> +#endif
>