1/*
  2 * Driver for Atmel Flexcom
  3 *
  4 * Copyright (C) 2015 Atmel Corporation
  5 *
  6 * Author: Cyrille Pitchen <cyrille.pitchen@atmel.com>
  7 *
  8 * This program is free software; you can redistribute it and/or modify
  9 * it under the terms of the GNU General Public License version 2 as
 10 * published by the Free Software Foundation.
 11 *
 12 * This program is distributed in the hope that it will be useful, but WITHOUT
 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 14 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 15 * more details.
 16 *
 17 * You should have received a copy of the GNU General Public License along with
 18 * this program.  If not, see <http://www.gnu.org/licenses/>.
 19 */
 20
 21#include <linux/module.h>
 22#include <linux/types.h>
 23#include <linux/kernel.h>
 24#include <linux/platform_device.h>
 25#include <linux/of.h>
 26#include <linux/of_platform.h>
 27#include <linux/err.h>
 28#include <linux/io.h>
 29#include <linux/clk.h>
 30#include <dt-bindings/mfd/atmel-flexcom.h>
 31
 32/* I/O register offsets */
 33#define FLEX_MR		0x0	/* Mode Register */
 34#define FLEX_VERSION	0xfc	/* Version Register */
 35
 36/* Mode Register bit fields */
 37#define FLEX_MR_OPMODE_OFFSET	(0)  /* Operating Mode */
 38#define FLEX_MR_OPMODE_MASK	(0x3 << FLEX_MR_OPMODE_OFFSET)
 39#define FLEX_MR_OPMODE(opmode)	(((opmode) << FLEX_MR_OPMODE_OFFSET) &	\
 40				 FLEX_MR_OPMODE_MASK)
 41
 42
 43static int atmel_flexcom_probe(struct platform_device *pdev)
 44{
 45	struct device_node *np = pdev->dev.of_node;
 46	struct clk *clk;
 47	struct resource *res;
 48	void __iomem *base;
 49	u32 opmode;
 50	int err;
 51
 52	err = of_property_read_u32(np, "atmel,flexcom-mode", &opmode);
 53	if (err)
 54		return err;
 55
 56	if (opmode < ATMEL_FLEXCOM_MODE_USART ||
 57	    opmode > ATMEL_FLEXCOM_MODE_TWI)
 58		return -EINVAL;
 59
 60	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 61	base = devm_ioremap_resource(&pdev->dev, res);
 62	if (IS_ERR(base))
 63		return PTR_ERR(base);
 64
 65	clk = devm_clk_get(&pdev->dev, NULL);
 66	if (IS_ERR(clk))
 67		return PTR_ERR(clk);
 68
 69	err = clk_prepare_enable(clk);
 70	if (err)
 71		return err;
 72
 73	/*
 74	 * Set the Operating Mode in the Mode Register: only the selected device
 75	 * is clocked. Hence, registers of the other serial devices remain
 76	 * inaccessible and are read as zero. Also the external I/O lines of the
 77	 * Flexcom are muxed to reach the selected device.
 78	 */
 79	writel(FLEX_MR_OPMODE(opmode), base + FLEX_MR);
 80
 81	clk_disable_unprepare(clk);
 82
 83	return of_platform_populate(np, NULL, NULL, &pdev->dev);
 84}
 85
 86static const struct of_device_id atmel_flexcom_of_match[] = {
 87	{ .compatible = "atmel,sama5d2-flexcom" },
 88	{ /* sentinel */ }
 89};
 90MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match);
 91
 92static struct platform_driver atmel_flexcom_driver = {
 93	.probe	= atmel_flexcom_probe,
 94	.driver	= {
 95		.name		= "atmel_flexcom",
 96		.of_match_table	= atmel_flexcom_of_match,
 97	},
 98};
 99
100module_platform_driver(atmel_flexcom_driver);
101
102MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>");
103MODULE_DESCRIPTION("Atmel Flexcom MFD driver");
104MODULE_LICENSE("GPL v2");