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
90static int __maybe_unused atmel_flexcom_resume_noirq(struct device *dev)
91{
92	struct atmel_flexcom *ddata = dev_get_drvdata(dev);
93	int err;
94	u32 val;
95
96	err = clk_prepare_enable(ddata->clk);
97	if (err)
98		return err;
99
100	val = FLEX_MR_OPMODE(ddata->opmode),
101	writel(val, ddata->base + FLEX_MR);
102
103	clk_disable_unprepare(ddata->clk);
104
105	return 0;
106}
107
108static const struct dev_pm_ops atmel_flexcom_pm_ops = {
109	.resume_noirq = atmel_flexcom_resume_noirq,
110};
111
112static struct platform_driver atmel_flexcom_driver = {
113	.probe	= atmel_flexcom_probe,
114	.driver	= {
115		.name		= "atmel_flexcom",
116		.pm		= pm_ptr(&atmel_flexcom_pm_ops),
117		.of_match_table	= atmel_flexcom_of_match,
118	},
119};
120
121module_platform_driver(atmel_flexcom_driver);
122
123MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>");
124MODULE_DESCRIPTION("Atmel Flexcom MFD driver");
125MODULE_LICENSE("GPL v2");
126