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
31 struct atmel_flexcom {
32 void __iomem *base;
33 u32 opmode;
34 struct clk *clk;
35 };
36
atmel_flexcom_probe(struct platform_device * pdev)37 static 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
84 static const struct of_device_id atmel_flexcom_of_match[] = {
85 { .compatible = "atmel,sama5d2-flexcom" },
86 { /* sentinel */ }
87 };
88 MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match);
89
90 #ifdef CONFIG_PM_SLEEP
atmel_flexcom_resume(struct device * dev)91 static 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
110 static SIMPLE_DEV_PM_OPS(atmel_flexcom_pm_ops, NULL,
111 atmel_flexcom_resume);
112
113 static 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
122 module_platform_driver(atmel_flexcom_driver);
123
124 MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>");
125 MODULE_DESCRIPTION("Atmel Flexcom MFD driver");
126 MODULE_LICENSE("GPL v2");
127