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Date:   Thu, 14 Jun 2018 09:58:49 +0200
From:   Ludovic Desroches <ludovic.desroches@microchip.com>
To:     Radu Pirea <radu.pirea@microchip.com>
CC:     <broonie@kernel.org>, <nicolas.ferre@microchip.com>,
        <alexandre.belloni@bootlin.com>, <lee.jones@linaro.org>,
        <richard.genoud@gmail.com>, <robh+dt@kernel.org>,
        <mark.rutland@arm.com>, <gregkh@linuxfoundation.org>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-spi@vger.kernel.org>, <linux-serial@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v7 3/6] mfd: at91-usart: added mfd driver for usart
Message-ID: <20180614075849.dfiqwcu6rtzgpzq7@rfolt0960.corp.atmel.com>
Mail-Followup-To: Radu Pirea <radu.pirea@microchip.com>, broonie@kernel.org,
        nicolas.ferre@microchip.com, alexandre.belloni@bootlin.com,
        lee.jones@linaro.org, richard.genoud@gmail.com, robh+dt@kernel.org,
        mark.rutland@arm.com, gregkh@linuxfoundation.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-spi@vger.kernel.org, linux-serial@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org
References: <20180613163621.23995-1-radu.pirea@microchip.com>
 <20180613163621.23995-4-radu.pirea@microchip.com>
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On Wed, Jun 13, 2018 at 07:36:18PM +0300, Radu Pirea wrote:
> This mfd driver is just a wrapper over atmel_serial driver and
> spi-at91-usart driver. Selection of one of the drivers is based on a
> property from device tree. If the property is not specified, the default
> driver is atmel_serial.
> 
> Signed-off-by: Radu Pirea <radu.pirea@microchip.com>
> Acked-by: Rob Herring <robh@kernel.org>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> Acked-for-MFD-by: Lee Jones <lee.jones@linaro.org>
> ---
>  drivers/mfd/Kconfig      |  9 ++++++
>  drivers/mfd/Makefile     |  1 +
>  drivers/mfd/at91-usart.c | 69 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 79 insertions(+)
>  create mode 100644 drivers/mfd/at91-usart.c
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index b860eb5aa194..a886672b960d 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -99,6 +99,15 @@ config MFD_AAT2870_CORE
>  	  additional drivers must be enabled in order to use the
>  	  functionality of the device.
>  
> +config MFD_AT91_USART
> +	tristate "AT91 USART Driver"
> +	select MFD_CORE
> +	help
> +	  Select this to get support for AT91 USART IP. This is a wrapper
> +	  over at91-usart-serial driver and usart-spi-driver. 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.
> +
>  config MFD_ATMEL_FLEXCOM
>  	tristate "Atmel Flexcom (Flexible Serial Communication Unit)"
>  	select MFD_CORE
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index d9d2cf0d32ef..db1332aa96db 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -185,6 +185,7 @@ 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-$(CONFIG_MFD_AT91_USART)	+= at91-usart.o
>  obj-$(CONFIG_MFD_ATMEL_FLEXCOM)	+= atmel-flexcom.o
>  obj-$(CONFIG_MFD_ATMEL_HLCDC)	+= atmel-hlcdc.o
>  obj-$(CONFIG_MFD_ATMEL_SMC)	+= atmel-smc.o
> diff --git a/drivers/mfd/at91-usart.c b/drivers/mfd/at91-usart.c
> new file mode 100644
> index 000000000000..3014ce532644
> --- /dev/null
> +++ b/drivers/mfd/at91-usart.c
> @@ -0,0 +1,69 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Driver for AT91 USART
> + *
> + * Copyright (C) 2018 Microchip Technology
> + *
> + * Author: Radu Pirea <radu.pirea@microchip.com>
> + *
> + */
> +
> +#include <dt-bindings/mfd/at91-usart.h>
> +
> +#include <linux/module.h>
> +#include <linux/mfd/core.h>
> +#include <linux/property.h>
> +
> +static struct mfd_cell at91_usart_spi_subdev = {
> +		.name = "at91_usart_spi",
> +		.of_compatible = "microchip,at91sam9g45-usart-spi",
> +	};
> +
> +static struct mfd_cell at91_usart_serial_subdev = {
> +		.name = "atmel_usart_serial",
> +		.of_compatible = "atmel,at91rm9200-usart-serial",
> +	};
> +
> +static int at91_usart_mode_probe(struct platform_device *pdev)
> +{
> +	struct mfd_cell cell;
> +	u32 opmode = AT91_USART_MODE_SERIAL;
> +
> +	device_property_read_u32(&pdev->dev, "atmel,usart-mode", &opmode);
> +
> +	switch (opmode) {
> +	case AT91_USART_MODE_SPI:
> +		cell = at91_usart_spi_subdev;
> +		break;
> +	case AT91_USART_MODE_SERIAL:
> +		cell = at91_usart_serial_subdev;
> +		break;
> +	default:
> +		break;

If there is an invalid opmode from the DT, you will pass a non initialized cell
to mfd_add_device().

Regards

Ludovic

> +	}
> +
> +	return devm_mfd_add_devices(&pdev->dev, PLATFORM_DEVID_AUTO, &cell, 1,
> +			      NULL, 0, NULL);
> +}
> +
> +static const struct of_device_id at91_usart_mode_of_match[] = {
> +	{ .compatible = "atmel,at91rm9200-usart" },
> +	{ .compatible = "atmel,at91sam9260-usart" },
> +	{ /* sentinel */ }
> +};
> +
> +MODULE_DEVICE_TABLE(of, at91_flexcom_of_match);
> +
> +static struct platform_driver at91_usart_mfd = {
> +	.probe	= at91_usart_mode_probe,
> +	.driver	= {
> +		.name		= "at91_usart_mode",
> +		.of_match_table	= at91_usart_mode_of_match,
> +	},
> +};
> +
> +module_platform_driver(at91_usart_mfd);
> +
> +MODULE_AUTHOR("Radu Pirea <radu.pirea@microchip.com>");
> +MODULE_DESCRIPTION("AT91 USART MFD driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.17.1
> 
> 
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