1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Driver for Atmel Flexcom
  4 *
  5 * Copyright (C) 2015 Atmel Corporation
  6 *
  7 * Author: Cyrille Pitchen <cyrille.pitchen@atmel.com>
  8 */
  9
 10#include <linux/module.h>
 11#include <linux/types.h>
 12#include <linux/kernel.h>
 13#include <linux/platform_device.h>
 14#include <linux/of.h>
 15#include <linux/of_platform.h>
 16#include <linux/err.h>
 17#include <linux/io.h>
 18#include <linux/clk.h>
 19#include <dt-bindings/mfd/atmel-flexcom.h>
 20
 21/* I/O register offsets */
 22#define FLEX_MR		0x0	/* Mode Register */
 23#define FLEX_VERSION	0xfc	/* Version Register */
 24
 25/* Mode Register bit fields */
 26#define FLEX_MR_OPMODE_OFFSET	(0)  /* Operating Mode */
 27#define FLEX_MR_OPMODE_MASK	(0x3 << FLEX_MR_OPMODE_OFFSET)
 28#define FLEX_MR_OPMODE(opmode)	(((opmode) << FLEX_MR_OPMODE_OFFSET) &	\
 29				 FLEX_MR_OPMODE_MASK)
 30
 31struct atmel_flexcom {
 32	void __iomem *base;
 33	u32 opmode;
 34	struct clk *clk;
 35};
 36
 37static int atmel_flexcom_probe(struct platform_device *pdev)
 38{
 39	struct device_node *np = pdev->dev.of_node;
 40	struct resource *res;
 41	struct atmel_flexcom *ddata;
 42	int err;
 43
 44	ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
 45	if (!ddata)
 46		return -ENOMEM;
 47
 48	platform_set_drvdata(pdev, ddata);
 49
 50	err = of_property_read_u32(np, "atmel,flexcom-mode", &ddata->opmode);
 51	if (err)
 52		return err;
 53
 54	if (ddata->opmode < ATMEL_FLEXCOM_MODE_USART ||
 55	    ddata->opmode > ATMEL_FLEXCOM_MODE_TWI)
 56		return -EINVAL;
 57
 58	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 59	ddata->base = devm_ioremap_resource(&pdev->dev, res);
 60	if (IS_ERR(ddata->base))
 61		return PTR_ERR(ddata->base);
 62
 63	ddata->clk = devm_clk_get(&pdev->dev, NULL);
 64	if (IS_ERR(ddata->clk))
 65		return PTR_ERR(ddata->clk);
 66
 67	err = clk_prepare_enable(ddata->clk);
 68	if (err)
 69		return err;
 70
 71	/*
 72	 * Set the Operating Mode in the Mode Register: only the selected device
 73	 * is clocked. Hence, registers of the other serial devices remain
 74	 * inaccessible and are read as zero. Also the external I/O lines of the
 75	 * Flexcom are muxed to reach the selected device.
 76	 */
 77	writel(FLEX_MR_OPMODE(ddata->opmode), ddata->base + FLEX_MR);
 78
 79	clk_disable_unprepare(ddata->clk);
 80
 81	return devm_of_platform_populate(&pdev->dev);
 82}
 83
 84static const struct of_device_id atmel_flexcom_of_match[] = {
 85	{ .compatible = "atmel,sama5d2-flexcom" },
 86	{ /* sentinel */ }
 87};
 88MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match);
 89
 90#ifdef CONFIG_PM_SLEEP
 91static int atmel_flexcom_resume(struct device *dev)
 92{
 93	struct atmel_flexcom *ddata = dev_get_drvdata(dev);
 94	int err;
 95	u32 val;
 96
 97	err = clk_prepare_enable(ddata->clk);
 98	if (err)
 99		return err;
100
101	val = FLEX_MR_OPMODE(ddata->opmode),
102	writel(val, ddata->base + FLEX_MR);
103
104	clk_disable_unprepare(ddata->clk);
105
106	return 0;
107}
108#endif
109
110static SIMPLE_DEV_PM_OPS(atmel_flexcom_pm_ops, NULL,
111			 atmel_flexcom_resume);
112
113static struct platform_driver atmel_flexcom_driver = {
114	.probe	= atmel_flexcom_probe,
115	.driver	= {
116		.name		= "atmel_flexcom",
117		.pm		= &atmel_flexcom_pm_ops,
118		.of_match_table	= atmel_flexcom_of_match,
119	},
120};
121
122module_platform_driver(atmel_flexcom_driver);
123
124MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>");
125MODULE_DESCRIPTION("Atmel Flexcom MFD driver");
126MODULE_LICENSE("GPL v2");