Re: [PATCH 1/3] drivers/mfd/menf21bmc: introduce MEN 14F021P00 BMC MFD Core driver

[Andreas Werner <andreas.werner@men.de>]

aOn Mon, May 19, 2014 at 06:39:53PM +0100, Lee Jones wrote:
> On Mon, 19 May 2014, Guenter Roeck wrote:
> 
> > On 05/19/2014 05:43 AM, Andreas Werner wrote:
> > >aOn Sat, May 17, 2014 at 08:47:42AM -0700, Guenter Roeck wrote:
> > >>On 05/16/2014 09:37 AM, Andreas Werner wrote:
> > >>>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@men.de>
> > >>>---
> > >>>  drivers/mfd/Kconfig           |  12 +++
> > >>>  drivers/mfd/Makefile          |   1 +
> > >>>  drivers/mfd/menf21bmc.c       | 193 ++++++++++++++++++++++++++++++++++++++++++
> > >>>  include/linux/mfd/menf21bmc.h |  32 +++++++
> > >>>  4 files changed, 238 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.
> > >>>+
> > >>>+
> > >>>  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..77de1a8
> > >>>--- /dev/null
> > >>>+++ b/drivers/mfd/menf21bmc.c
> > >>>@@ -0,0 +1,193 @@
> > >>>+/*
> > >>>+ *  MEN 14F021P00 Board Management Controller (BMC) MFD Core Driver.
> > >>>+ *
> > >>>+ *  Copyright (C) 2014 MEN Mikro Elektronik Nuernberg GmbH
> > >>>+ *  Author: Andreas Werner <andreas.werner@men.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
> > >>>+
> > >>>+static struct mfd_cell menf21bmc_cell[] = {
> > >>>+	{
> > >>>+		.name = "menf21bmc_wd",
> > >>>+	},
> > >>>+	{
> > >>>+		.name = "menf21bmc_led",
> > >>>+	},
> > >>>+};
> > >>>+
> > >>>+static int
> > >>>+menf21bmc_read_byte_data(struct i2c_client *client, u8 reg, uint8_t *val)
> > >>>+{
> > >>>+	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);
> > >>>+
> > >>>+	if (ret < 0) {
> > >>>+		dev_err(&client->dev, "failed to read byte at 0x%02x\n", reg);
> > >>>+		return ret;
> > >>>+	}
> > >>>+
> > >>>+	*val = (uint8_t)ret;
> > >>>+
> > >>>+	return 0;
> > >>>+}
> > >>>+
> > >>I personally would prefer if you would retain the original API, which returns both value
> > >>and error code as return value. I don't see the benefit of changing the API as you did -
> > >>it just complicates the code.
> > >>
> > >>Thanks,
> > >>Guenter
> > >>
> > >I think it is ok for a wrapper like this because it does not really change an API because
> > >it is menf21bmc related.
> > >
> > >I did the same in rtc-rx8581, and it was already done in rtc_ds1307.c.
> > >
> > >I personally prefer this way because the return of the function and the return
> > >value of the i2c_smbus_read - which is the value read from the device - are seperated.
> > >
> > >If it is a no go for the mfd/wdt core i can change it back to the original i2c_smbus API.
> > >If it is ok on your side for a wrapper like this, we can let it as it is.
> > >
> > 
> > Not my call to make; depends on the mfd maintainer. I would not accept it, as I see it
> > as unnecessary, adding complexity, and pointless. Sure, you can always find examples
> > for everything somewhere in the kernel, but that doesn't make it better.
> 
> I'm inclined to agree with Guenter, this patch is just noise.

Ok no problem, i will fix it and resend the patch.
For now I know it for the future :-)

Any other comments about the patch series?

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