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5c41f11c CP |
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 | ||
43 | static 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 | ||
86 | static const struct of_device_id atmel_flexcom_of_match[] = { | |
87 | { .compatible = "atmel,sama5d2-flexcom" }, | |
88 | { /* sentinel */ } | |
89 | }; | |
90 | MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match); | |
91 | ||
92 | static 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 | ||
100 | module_platform_driver(atmel_flexcom_driver); | |
101 | ||
102 | MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>"); | |
103 | MODULE_DESCRIPTION("Atmel Flexcom MFD driver"); | |
104 | MODULE_LICENSE("GPL v2"); |