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Message-ID: <20150724084355.GY3436@x1>
Date: Fri, 24 Jul 2015 09:43:55 +0100
From: Lee Jones <lee.jones@...aro.org>
To: Cyrille Pitchen <cyrille.pitchen@...el.com>
Cc: nicolas.ferre@...el.com, 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
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.
> + 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");
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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