Date:	Tue, 27 May 2014 16:05:47 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Andreas Werner <andreas.werner@....de>
Cc:	linux-kernel@...r.kernel.org, sameo@...ux.intel.com, wim@...ana.be,
	linux-watchdog@...r.kernel.org, cooloney@...il.com,
	rpurdie@...ys.net, linux-leds@...r.kernel.org,
	johannes.thumshirn@....de
Subject: Re: [PATCH v2 1/3] drivers/mfd/menf21bmc: introduce MEN 14F021P00
 BMC MFD Core driver

> The MEN 14F021P00 Board Management Controller provides an
> I2C interface to the host to access the feature implemented in the BMC.
> The BMC is a PIC Microntroller assembled on CPCI Card from MEN Mikroelektronik
> and on a few Box/Display Computer.
> 
> Added MFD Core driver, supporting the I2C communication to the device.
> 
> The MFD driver currently supports the following features:
> 	- Watchdog
> 	- LEDs
> 
> Signed-off-by: Andreas Werner <andreas.werner@....de>
> ---
>  drivers/mfd/Kconfig           |  12 +++
>  drivers/mfd/Makefile          |   1 +
>  drivers/mfd/menf21bmc.c       | 220 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/menf21bmc.h |  31 ++++++
>  4 files changed, 264 insertions(+)
>  create mode 100644 drivers/mfd/menf21bmc.c
>  create mode 100644 include/linux/mfd/menf21bmc.h
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index ab5a43c..7c2e8d2 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -427,6 +427,18 @@ config MFD_MAX8998
>  	  additional drivers must be enabled in order to use the functionality
>  	  of the device.
>  
> +config MFD_MENF21BMC
> +	tristate "MEN 14F021P00 Board Management Controller Support"
> +	depends on I2C=y
> +	select MFD_CORE
> +	help
> +	  Say yes here to add support for the MEN 14F021P00 BMC
> +	  which is a Board Management Controller connected to the I2C bus.
> +	  This driver provides common support for accessing the devices;
> +	  additional drivers must be enabled in order to use the
> +	  functionality of the BMC device.

Would be good if you mention the WD and LED devices here too.

> +
> +

To many '\n's here.

>  config EZX_PCAP
>  	bool "Motorola EZXPCAP Support"
>  	depends on SPI_MASTER
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 5913208..8f2be38 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -167,3 +167,4 @@ obj-$(CONFIG_MFD_AS3711)	+= as3711.o
>  obj-$(CONFIG_MFD_AS3722)	+= as3722.o
>  obj-$(CONFIG_MFD_STW481X)	+= stw481x.o
>  obj-$(CONFIG_MFD_IPAQ_MICRO)	+= ipaq-micro.o
> +obj-$(CONFIG_MFD_MENF21BMC)	+= menf21bmc.o
> diff --git a/drivers/mfd/menf21bmc.c b/drivers/mfd/menf21bmc.c
> new file mode 100644
> index 0000000..8de92b5
> --- /dev/null
> +++ b/drivers/mfd/menf21bmc.c
> @@ -0,0 +1,220 @@
> +/*
> + *  MEN 14F021P00 Board Management Controller (BMC) MFD Core Driver.
> + *
> + *  Copyright (C) 2014 MEN Mikro Elektronik Nuernberg GmbH
> + *  Author: Andreas Werner <andreas.werner@....de>
> + *  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.
> + *
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/menf21bmc.h>
> +
> +#define BMC_CMD_REV_MAJOR	0x80
> +#define BMC_CMD_REV_MINOR	0x81
> +#define BMC_CMD_REV_MAIN	0x82
> +#define BMC_CMD_REV_BUILD	0x83
> +#define BMC_CMD_REV_VERI	0x84
> +#define BMC_CMD_WD_ARM_SET	0x18
> +#define BMC_CMD_WD_ARM_GET	0x19
> +
> +static struct mfd_cell menf21bmc_cell[] = {
> +	{
> +		.name = "menf21bmc_wd",

I prefer wdog to wd, as it's a little move obvious what we're dealing
with.

> +	},
> +	{
> +		.name = "menf21bmc_led",
> +	},
> +};

If these are the only struct attributes, please place them on a single
line (each).

> +static int
> +menf21bmc_read_byte_data(struct i2c_client *client, u8 reg)
> +{
> +	int ret;
> +	struct menf21bmc *data = i2c_get_clientdata(client);
> +
> +	mutex_lock(&data->lock);
> +	ret = i2c_smbus_read_byte_data(client, reg);
> +	mutex_unlock(&data->lock);
> +
> +	return ret;
> +}
> +
> +static int
> +menf21bmc_read_word_data(struct i2c_client *client, u8 reg)
> +{
> +	int ret;
> +	struct menf21bmc *data = i2c_get_clientdata(client);
> +
> +	mutex_lock(&data->lock);
> +	ret = i2c_smbus_read_word_data(client, reg);
> +	mutex_unlock(&data->lock);
> +
> +	return ret;
> +}
> +
> +static int menf21bmc_write_byte_data(struct i2c_client *client, u8 reg, u8 val)
> +{
> +	int ret;
> +	struct menf21bmc *data = i2c_get_clientdata(client);
> +
> +	mutex_lock(&data->lock);
> +	ret = i2c_smbus_write_byte_data(client, reg, val);
> +	mutex_unlock(&data->lock);
> +
> +	return ret;
> +}
> +
> +static int menf21bmc_write_word_data(struct i2c_client *client, u8 reg, u16 val)
> +{
> +	int ret;
> +	struct menf21bmc *data = i2c_get_clientdata(client);
> +
> +	mutex_lock(&data->lock);
> +	ret = i2c_smbus_write_word_data(client, reg, val);
> +	mutex_unlock(&data->lock);
> +
> +	return ret;
> +}
> +
> +static int menf21bmc_write_byte(struct i2c_client *client, u8 val)
> +{
> +	int ret;
> +	struct menf21bmc *data = i2c_get_clientdata(client);
> +
> +	mutex_lock(&data->lock);
> +	ret = i2c_smbus_write_byte(client, val);
> +	mutex_unlock(&data->lock);
> +
> +	return ret;
> +}

Didn't we ask you to remove these?  Just make the i2c_smbus_* calls
from within the driver.  The I2C subsystem conducts its own locking.
I'm really starting to frown on aggregation for the sake of
aggregation.  It's just overhead.

> +static int menf21bmc_wd_leave_prod_mode(struct i2c_client *client)
> +{
> +	int val, ret;
> +
> +	val = menf21bmc_read_byte_data(client, BMC_CMD_WD_ARM_GET);

ARM like the processor, or 'arm' as in "arm the missile", or something
else?

> +	if (val < 0)
> +		return val;
> +
> +	/*
> +	 * Production mode should be not active after delivery of the Board.
> +	 * To be sure we check it, inform the user and leave the mode
> +	 * if active.
> +	 */

I prefer the term 'exit', as 'leave' is ambiguous.  It could read
"leave it in production mode", or "leave (exit) production mode".

> +	if (val == 0x00) {
> +		dev_info(&client->dev,
> +			"BMC in production mode. Leave production mode\n");
> +
> +		ret = menf21bmc_write_byte(client, BMC_CMD_WD_ARM_SET);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int
> +menf21bmc_probe(struct i2c_client *client, const struct i2c_device_id *ids)
> +{
> +	int ret;
> +	struct menf21bmc *data;
> +	int rev_major, rev_minor, rev_main;
> +
> +	if (!i2c_check_functionality(client->adapter,
> +						I2C_FUNC_SMBUS_BYTE_DATA |
> +						I2C_FUNC_SMBUS_WORD_DATA |
> +						I2C_FUNC_SMBUS_BYTE))

Tabbing is off.  Try to line up with the '('.

> +		return -EIO;

-ENODEV is more common.

> +	data = devm_kzalloc(&client->dev, sizeof(struct menf21bmc), GFP_KERNEL);

s/sizeof(struct menf21bmc)/sizeof(*data)/

data doesn't tend to be a good name for a variable.

> +	if (data == NULL)

if (!data)

> +		return -ENOMEM;
> +
> +	mutex_init(&data->lock);
> +
> +	i2c_set_clientdata(client, data);
> +	data->client = client;
> +	data->read_word_data = menf21bmc_read_word_data;
> +	data->read_byte_data = menf21bmc_read_byte_data;
> +	data->write_word_data = menf21bmc_write_word_data;
> +	data->write_byte_data = menf21bmc_write_byte_data;
> +	data->write_byte = menf21bmc_write_byte;

Yuck, please remove these.

> +	rev_major = menf21bmc_read_word_data(client, BMC_CMD_REV_MAJOR);
> +	if (rev_major < 0) {
> +		dev_err(&client->dev, "failed to get BMC major revision\n");
> +		return rev_major;
> +	}
> +
> +	rev_minor = menf21bmc_read_word_data(client, BMC_CMD_REV_MINOR);
> +	if (rev_minor < 0) {
> +		dev_err(&client->dev, "failed to get BMC minor revision\n");
> +		return rev_minor;
> +	}
> +
> +	rev_main = menf21bmc_read_word_data(client, BMC_CMD_REV_MAIN);
> +	if (rev_main < 0) {
> +		dev_err(&client->dev, "failed to get BMC main revision\n");
> +		return rev_main;
> +	}
> +
> +	dev_info(&client->dev, "FW Revision: %02d.%02d.%02d\n",
> +					rev_major, rev_minor, rev_main);
> +
> +	/*
> +	 * We have to leave the Production Mode of the BMC to activate the
> +	 * Watchdog functionality and the BIOS life sign monitoring.
> +	 */
> +	ret = menf21bmc_wd_leave_prod_mode(client);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "failed to leave production mode\n");
> +		return ret;
> +	}

Is it possible that someone might want to use production mode?

> +	ret = mfd_add_devices(&client->dev, 0, menf21bmc_cell,
> +				ARRAY_SIZE(menf21bmc_cell), NULL, 0, NULL);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "mfd_add_devices failed\n");

This error message should be more useful to the user.

E.g. "Failed to add sub-devices"

> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int menf21bmc_remove(struct i2c_client *client)
> +{
> +	mfd_remove_devices(&client->dev);
> +	return 0;
> +}
> +
> +static const struct i2c_device_id menf21bmc_id_table[] = {
> +	{"menf21bmc", 0},

Please add a ' ' after '{' and before '}'.

> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, menf21bmc_id_table);
> +
> +static struct i2c_driver menf21bmc_driver = {
> +	.driver		= {
> +		.name	= "menf21bmc",
> +		.owner	= THIS_MODULE,
> +	},
> +	.id_table	= menf21bmc_id_table,
> +	.probe		= menf21bmc_probe,
> +	.remove		= menf21bmc_remove,
> +};
> +
> +module_i2c_driver(menf21bmc_driver);
> +
> +MODULE_DESCRIPTION("MEN 14F021P00 BMC mfd core driver");
> +MODULE_AUTHOR("Andreas Werner <andreas.werner@....de");

Missing '>'.

> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/mfd/menf21bmc.h b/include/linux/mfd/menf21bmc.h
> new file mode 100644
> index 0000000..1fc9b5c
> --- /dev/null
> +++ b/include/linux/mfd/menf21bmc.h
> @@ -0,0 +1,31 @@
> +/*
> + *  MEN 14F021P00 Board Management Controller (BMC)
> + *
> + *  Copyright (C) 2014 MEN Mikro Elektronik Nuernberg GmbH
> + *  Author: Andreas Werner <andreas.werner@....de>
> + *  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.
> + *
> + */
> +
> +#ifndef MENF21BMC_H
> +#define MENF21BMC_H
> +
> +struct menf21bmc {
> +	struct i2c_client *client;
> +	struct mutex lock;
> +
> +	int (*read_word_data)(struct i2c_client *client, u8 reg);
> +	int (*read_byte_data)(struct i2c_client *client, u8 reg);
> +	int (*write_word_data)(struct i2c_client *client, u8 reg, u16 val);
> +	int (*write_byte_data)(struct i2c_client *client, u8 reg, u8 val);
> +	int (*write_byte)(struct i2c_client *client, u8 val);
> +};
> +
> +#endif /* MENF21BMC_H */
> +
> +

Too many '\n's here.

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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