Commit 5c41f11c authored by Cyrille Pitchen's avatar Cyrille Pitchen Committed by Lee Jones
Browse files

mfd: atmel-flexcom: Add a driver for Atmel Flexible Serial Communication Unit 



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, according to the value of the new
"atmel,flexcom-mode" device tree property.

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: default avatarCyrille Pitchen <cyrille.pitchen@atmel.com>
Acked-by: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: default avatarNicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
parent c335bd5d

drivers/mfd/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -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.



config MFD_ATMEL_HLCDC

	tristate "Atmel HLCDC (High-end LCD Controller)"

	select MFD_CORE

drivers/mfd/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -164,6 +164,7 @@ 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_LPSS)	+= intel-lpss.o

obj-$(CONFIG_MFD_INTEL_LPSS_PCI)	+= intel-lpss-pci.o

drivers/mfd/atmel-flexcom.c

0 → 100644
+104 −0
Original line number Diff line number Diff line 
/*

 * Driver for Atmel Flexcom

 *

 * Copyright (C) 2015 Atmel Corporation

 *

 * Author: Cyrille Pitchen <cyrille.pitchen@atmel.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>

#include <dt-bindings/mfd/atmel-flexcom.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_OFFSET	(0)  /* Operating Mode */

#define FLEX_MR_OPMODE_MASK	(0x3 << FLEX_MR_OPMODE_OFFSET)

#define FLEX_MR_OPMODE(opmode)	(((opmode) << FLEX_MR_OPMODE_OFFSET) &	\

				 FLEX_MR_OPMODE_MASK)





static int atmel_flexcom_probe(struct platform_device *pdev)

{

	struct device_node *np = pdev->dev.of_node;

	struct clk *clk;

	struct resource *res;

	void __iomem *base;

	u32 opmode;

	int err;



	err = of_property_read_u32(np, "atmel,flexcom-mode", &opmode);

	if (err)

		return err;



	if (opmode < ATMEL_FLEXCOM_MODE_USART ||

	    opmode > ATMEL_FLEXCOM_MODE_TWI)

		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(FLEX_MR_OPMODE(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@atmel.com>");

MODULE_DESCRIPTION("Atmel Flexcom MFD driver");

MODULE_LICENSE("GPL v2");

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