xref: /openbmc/u-boot/drivers/bootcount/rtc.c (revision d94604d5)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * (C) Copyright 2018 Theobroma Systems Design und Consulting GmbH
4  */
5 
6 #include <common.h>
7 #include <bootcount.h>
8 #include <dm.h>
9 #include <rtc.h>
10 
11 static const u8 bootcount_magic = 0xbc;
12 
13 struct bootcount_rtc_priv {
14 	struct udevice *rtc;
15 	u32 offset;
16 };
17 
bootcount_rtc_set(struct udevice * dev,const u32 a)18 static int bootcount_rtc_set(struct udevice *dev, const u32 a)
19 {
20 	struct bootcount_rtc_priv *priv = dev_get_priv(dev);
21 	const u16 val = bootcount_magic << 8 | (a & 0xff);
22 
23 	if (rtc_write16(priv->rtc, priv->offset, val) < 0) {
24 		debug("%s: rtc_write16 failed\n", __func__);
25 		return -EIO;
26 	}
27 
28 	return 0;
29 }
30 
bootcount_rtc_get(struct udevice * dev,u32 * a)31 static int bootcount_rtc_get(struct udevice *dev, u32 *a)
32 {
33 	struct bootcount_rtc_priv *priv = dev_get_priv(dev);
34 	u16 val;
35 
36 	if (rtc_read16(priv->rtc, priv->offset, &val) < 0) {
37 		debug("%s: rtc_write16 failed\n", __func__);
38 		return -EIO;
39 	}
40 
41 	if (val >> 8 == bootcount_magic) {
42 		*a = val & 0xff;
43 		return 0;
44 	}
45 
46 	debug("%s: bootcount magic does not match on %04x\n", __func__, val);
47 	return -EIO;
48 }
49 
bootcount_rtc_probe(struct udevice * dev)50 static int bootcount_rtc_probe(struct udevice *dev)
51 {
52 	struct ofnode_phandle_args phandle_args;
53 	struct bootcount_rtc_priv *priv = dev_get_priv(dev);
54 	struct udevice *rtc;
55 
56 	if (dev_read_phandle_with_args(dev, "rtc", NULL, 0, 0, &phandle_args)) {
57 		debug("%s: rtc backing device not specified\n", dev->name);
58 		return -ENOENT;
59 	}
60 
61 	if (uclass_get_device_by_ofnode(UCLASS_RTC, phandle_args.node, &rtc)) {
62 		debug("%s: could not get backing device\n", dev->name);
63 		return -ENODEV;
64 	}
65 
66 	priv->rtc = rtc;
67 	priv->offset = dev_read_u32_default(dev, "offset", 0);
68 
69 	return 0;
70 }
71 
72 static const struct bootcount_ops bootcount_rtc_ops = {
73 	.get = bootcount_rtc_get,
74 	.set = bootcount_rtc_set,
75 };
76 
77 static const struct udevice_id bootcount_rtc_ids[] = {
78 	{ .compatible = "u-boot,bootcount-rtc" },
79 	{ }
80 };
81 
82 U_BOOT_DRIVER(bootcount_rtc) = {
83 	.name	= "bootcount-rtc",
84 	.id	= UCLASS_BOOTCOUNT,
85 	.priv_auto_alloc_size = sizeof(struct bootcount_rtc_priv),
86 	.probe	= bootcount_rtc_probe,
87 	.of_match = bootcount_rtc_ids,
88 	.ops	= &bootcount_rtc_ops,
89 };
90