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 atmel_flexcom *ddata;
41	int err;
42
43	ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
44	if (!ddata)
45		return -ENOMEM;
46
47	platform_set_drvdata(pdev, ddata);
48
49	err = of_property_read_u32(np, "atmel,flexcom-mode", &ddata->opmode);
50	if (err)
51		return err;
52
53	if (ddata->opmode < ATMEL_FLEXCOM_MODE_USART ||
54	    ddata->opmode > ATMEL_FLEXCOM_MODE_TWI)
55		return -EINVAL;
56
57	ddata->base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
58	if (IS_ERR(ddata->base))
59		return PTR_ERR(ddata->base);
60
61	ddata->clk = devm_clk_get(&pdev->dev, NULL);
62	if (IS_ERR(ddata->clk))
63		return PTR_ERR(ddata->clk);
64
65	err = clk_prepare_enable(ddata->clk);
66	if (err)
67		return err;
68
69	/*
70	 * Set the Operating Mode in the Mode Register: only the selected device
71	 * is clocked. Hence, registers of the other serial devices remain
72	 * inaccessible and are read as zero. Also the external I/O lines of the
73	 * Flexcom are muxed to reach the selected device.
74	 */
75	writel(FLEX_MR_OPMODE(ddata->opmode), ddata->base + FLEX_MR);
76
77	clk_disable_unprepare(ddata->clk);
78
79	return devm_of_platform_populate(&pdev->dev);
80}
81
82static const struct of_device_id atmel_flexcom_of_match[] = {
83	{ .compatible = "atmel,sama5d2-flexcom" },
84	{ /* sentinel */ }
85};
86MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match);
87
88static int __maybe_unused atmel_flexcom_resume_noirq(struct device *dev)
89{
90	struct atmel_flexcom *ddata = dev_get_drvdata(dev);
91	int err;
92	u32 val;
93
94	err = clk_prepare_enable(ddata->clk);
95	if (err)
96		return err;
97
98	val = FLEX_MR_OPMODE(ddata->opmode),
99	writel(val, ddata->base + FLEX_MR);
100
101	clk_disable_unprepare(ddata->clk);
102
103	return 0;
104}
105
106static const struct dev_pm_ops __maybe_unused atmel_flexcom_pm_ops = {
107	.resume_noirq = atmel_flexcom_resume_noirq,
108};
109
110static struct platform_driver atmel_flexcom_driver = {
111	.probe	= atmel_flexcom_probe,
112	.driver	= {
113		.name		= "atmel_flexcom",
114		.pm		= pm_ptr(&atmel_flexcom_pm_ops),
115		.of_match_table	= atmel_flexcom_of_match,
116	},
117};
118
119module_platform_driver(atmel_flexcom_driver);
120
121MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>");
122MODULE_DESCRIPTION("Atmel Flexcom MFD driver");
123MODULE_LICENSE("GPL v2");
124