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Message-ID: <20140520074748.GC398@awelinux>
Date: Tue, 20 May 2014 09:47:49 +0200
From: Andreas Werner <andreas.werner@....de>
To: Lee Jones <lee.jones@...aro.org>
CC: Guenter Roeck <linux@...ck-us.net>,
Andreas Werner <andreas.werner@....de>,
<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>,
<thomas.schnuerer@....de>, <wernerandy@....de>
Subject: Re: [PATCH 1/3] drivers/mfd/menf21bmc: introduce MEN 14F021P00 BMC
MFD Core driver
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@....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@....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
> Follow Linaro: Facebook | Twitter | Blog
Regards
Andy
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