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Message-ID: <20140519124324.GB398@awelinux>
Date: Mon, 19 May 2014 14:43:24 +0200
From: Andreas Werner <andreas.werner@....de>
To: Guenter Roeck <linux@...ck-us.net>
CC: Andreas Werner <andreas.werner@....de>,
<linux-kernel@...r.kernel.org>, <sameo@...ux.intel.com>,
<lee.jones@...aro.org>, <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 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.
Thanks
Andy
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