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Message-ID: <55B1FB87.4040508@atmel.com>
Date: Fri, 24 Jul 2015 10:47:03 +0200
From: Nicolas Ferre <nicolas.ferre@...el.com>
To: Lee Jones <lee.jones@...aro.org>,
Cyrille Pitchen <cyrille.pitchen@...el.com>
CC: <boris.brezillon@...e-electrons.com>,
<alexandre.belloni@...e-electrons.com>, <sameo@...ux.intel.com>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>, <robh+dt@...nel.org>,
<pawel.moll@....com>, <mark.rutland@....com>,
<ijc+devicetree@...lion.org.uk>, <galak@...eaurora.org>,
<devicetree@...r.kernel.org>
Subject: Re: [PATCH v7 2/2] mfd: atmel-flexcom: add a driver for Atmel Flexible
Serial Communication Unit
Le 24/07/2015 10:43, Lee Jones a écrit :
> On Thu, 23 Jul 2015, Cyrille Pitchen wrote:
>
>> This driver supports the new Atmel Flexcom. The Flexcom is a wrapper which
>> integrates one SPI controller, one I2C controller and one USART. Only one
>> function can be enabled at a time. This driver selects the function once
>> for all, when the Flexcom is probed, using the "reg" property of the first
>> (should be unique) available DT child node.
>>
>> This driver has chosen to present the Flexcom to the system as a MFD so
>> the implementation is seamless for the existing Atmel SPI, I2C and USART
>> drivers.
>>
>> Also the Flexcom embeds FIFOs: the latest patches of the SPI, I2C and
>> USART drivers take advantage of this new feature.
>>
>> Signed-off-by: Cyrille Pitchen <cyrille.pitchen@...el.com>
>> ---
>> drivers/mfd/Kconfig | 11 +++++
>> drivers/mfd/Makefile | 1 +
>> drivers/mfd/atmel-flexcom.c | 113 ++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 125 insertions(+)
>> create mode 100644 drivers/mfd/atmel-flexcom.c
>>
>> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
>> index 653815950aa2..2c75472c679c 100644
>> --- a/drivers/mfd/Kconfig
>> +++ b/drivers/mfd/Kconfig
>> @@ -60,6 +60,17 @@ config MFD_AAT2870_CORE
>> additional drivers must be enabled in order to use the
>> functionality of the device.
>>
>> +config MFD_ATMEL_FLEXCOM
>> + tristate "Atmel Flexcom (Flexible Serial Communication Unit)"
>> + select MFD_CORE
>> + depends on OF
>> + help
>> + Select this to get support for Atmel Flexcom. This is a wrapper
>> + which embeds a SPI controller, a I2C controller and a USART. Only
>> + one function can be used at a time. The choice is done at boot time
>> + by the probe function of this MFD driver according to a device tree
>> + property.
>
> Please grep for QCOM_GSBI in drivers/soc/qcom/*
>
> Similar right?
>
> Perhaps this should live in drivers/soc/atmel/* instead?
>
>> config MFD_ATMEL_HLCDC
>> tristate "Atmel HLCDC (High-end LCD Controller)"
>> select MFD_CORE
>> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
>> index ea40e076cb61..0705eb2d873d 100644
>> --- a/drivers/mfd/Makefile
>> +++ b/drivers/mfd/Makefile
>> @@ -160,6 +160,7 @@ obj-$(CONFIG_MFD_SPMI_PMIC) += qcom-spmi-pmic.o
>> obj-$(CONFIG_TPS65911_COMPARATOR) += tps65911-comparator.o
>> obj-$(CONFIG_MFD_TPS65090) += tps65090.o
>> obj-$(CONFIG_MFD_AAT2870_CORE) += aat2870-core.o
>> +obj-$(CONFIG_MFD_ATMEL_FLEXCOM) += atmel-flexcom.o
>> obj-$(CONFIG_MFD_ATMEL_HLCDC) += atmel-hlcdc.o
>> obj-$(CONFIG_MFD_INTEL_MSIC) += intel_msic.o
>> obj-$(CONFIG_MFD_PALMAS) += palmas.o
>> diff --git a/drivers/mfd/atmel-flexcom.c b/drivers/mfd/atmel-flexcom.c
>> new file mode 100644
>> index 000000000000..0d06b70696b0
>> --- /dev/null
>> +++ b/drivers/mfd/atmel-flexcom.c
>> @@ -0,0 +1,113 @@
>> +/*
>> + * Driver for Atmel Flexcom
>> + *
>> + * Copyright (C) 2015 Atmel Corporation
>> + *
>> + * Author: Cyrille Pitchen <cyrille.pitchen@...el.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful, but WITHOUT
>> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
>> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
>> + * more details.
>> + *
>> + * You should have received a copy of the GNU General Public License along with
>> + * this program. If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/types.h>
>> +#include <linux/kernel.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/of.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/err.h>
>> +#include <linux/io.h>
>> +#include <linux/clk.h>
>> +
>> +/* I/O register offsets */
>> +#define FLEX_MR 0x0 /* Mode Register */
>> +#define FLEX_VERSION 0xfc /* Version Register */
>> +
>> +/* Mode Register bit fields */
>> +#define FLEX_MR_OPMODE_MASK 0x3
>> +#define FLEX_MR_OPMODE_NO_COM 0x0
>> +#define FLEX_MR_OPMODE_USART 0x1
>> +#define FLEX_MR_OPMODE_SPI 0x2
>> +#define FLEX_MR_OPMODE_TWI 0x3
>> +
>> +
>> +static int atmel_flexcom_probe(struct platform_device *pdev)
>> +{
>> + struct device_node *child, *np = pdev->dev.of_node;
>> + struct clk *clk;
>> + struct resource *res;
>> + void __iomem *base;
>> + u32 opmode;
>> + int err;
>> +
>> + child = of_get_next_available_child(np, NULL);
>> + if (!child)
>> + return -ENODEV;
>> +
>> + /*
>> + * The Operating Mode is stored into the first u32 of the reg property
>> + * of the child.
>> + */
>> + err = of_property_read_u32_index(child, "reg", 0, &opmode);
>> + of_node_put(child);
>
> Don't think you need to of_node_put() after a u32 read.
Well, it's after an of_get_next_available_child() which is similar to
of_get_next_child(). It is said to release the node by calling
of_node_put()... So I suspect it's necessary.
Bye,
>
>> + if (err)
>> + return -EINVAL;
>
> Why are you making up your own return value.
>
> Just return err.
>
>> + if ((opmode == FLEX_MR_OPMODE_NO_COM) ||
>> + (opmode & ~FLEX_MR_OPMODE_MASK))
>> + return -EINVAL;
>> +
>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> + base = devm_ioremap_resource(&pdev->dev, res);
>> + if (IS_ERR(base))
>> + return PTR_ERR(base);
>> +
>> + clk = devm_clk_get(&pdev->dev, NULL);
>> + if (IS_ERR(clk))
>> + return PTR_ERR(clk);
>> +
>> + err = clk_prepare_enable(clk);
>> + if (err)
>> + return err;
>> +
>> + /*
>> + * Set the Operating Mode in the Mode Register: only the selected device
>> + * is clocked. Hence, registers of the other serial devices remain
>> + * inaccessible and are read as zero. Also the external I/O lines of the
>> + * Flexcom are muxed to reach the selected device.
>> + */
>> + writel(opmode, base + FLEX_MR);
>> +
>> + clk_disable_unprepare(clk);
>> +
>> + return of_platform_populate(np, NULL, NULL, &pdev->dev);
>> +}
>> +
>> +static const struct of_device_id atmel_flexcom_of_match[] = {
>> + { .compatible = "atmel,sama5d2-flexcom" },
>> + { /* sentinel */ }
>> +};
>> +MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match);
>> +
>> +static struct platform_driver atmel_flexcom_driver = {
>> + .probe = atmel_flexcom_probe,
>> + .driver = {
>> + .name = "atmel_flexcom",
>> + .of_match_table = atmel_flexcom_of_match,
>> + },
>> +};
>> +
>> +module_platform_driver(atmel_flexcom_driver);
>> +
>> +MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@...el.com>");
>> +MODULE_DESCRIPTION("Atmel Flexcom MFD driver");
>> +MODULE_LICENSE("GPL v2");
>
--
Nicolas Ferre
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