1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright 2023, Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
4 *
5 * This driver supports the Google Goldfish virtual platform RTC device.
6 * The device is provided by the RISC-V virt machine in QEMU. It exposes
7 * a 64-bit nanosecond timer via two memory-mapped 32-bit registers.
8 */
9
10 #include <div64.h>
11 #include <dm.h>
12 #include <mapmem.h>
13 #include <rtc.h>
14 #include <linux/io.h>
15
16 /**
17 * struct goldfish_rtc - private data for RTC driver
18 */
19 struct goldfish_rtc {
20 /**
21 * @base: base address for register file
22 */
23 void __iomem *base;
24 /**
25 * @isdst: daylight saving time
26 */
27 int isdst;
28 };
29
30 /* Register offsets */
31 #define GOLDFISH_TIME_LOW 0x00
32 #define GOLDFISH_TIME_HIGH 0x04
33
goldfish_rtc_get(struct udevice * dev,struct rtc_time * time)34 static int goldfish_rtc_get(struct udevice *dev, struct rtc_time *time)
35 {
36 struct goldfish_rtc *priv = dev_get_priv(dev);
37 void __iomem *base = priv->base;
38 u64 time_high;
39 u64 time_low;
40 u64 now;
41
42 time_low = ioread32(base + GOLDFISH_TIME_LOW);
43 time_high = ioread32(base + GOLDFISH_TIME_HIGH);
44 now = (time_high << 32) | time_low;
45
46 do_div(now, 1000000000U);
47
48 rtc_to_tm(now, time);
49 time->tm_isdst = priv->isdst;
50
51 return 0;
52 }
53
goldfish_rtc_set(struct udevice * dev,const struct rtc_time * time)54 static int goldfish_rtc_set(struct udevice *dev, const struct rtc_time *time)
55 {
56 struct goldfish_rtc *priv = dev_get_priv(dev);
57 void __iomem *base = priv->base;
58 u64 now;
59
60 if (time->tm_year < 1970)
61 return -EINVAL;
62
63 now = rtc_mktime(time) * 1000000000ULL;
64 iowrite32(now >> 32, base + GOLDFISH_TIME_HIGH);
65 iowrite32(now, base + GOLDFISH_TIME_LOW);
66
67 if (time->tm_isdst > 0)
68 priv->isdst = 1;
69 else if (time->tm_isdst < 0)
70 priv->isdst = -1;
71 else
72 priv->isdst = 0;
73
74 return 0;
75 }
76
goldfish_rtc_probe(struct udevice * dev)77 static int goldfish_rtc_probe(struct udevice *dev)
78 {
79 struct goldfish_rtc *priv = dev_get_priv(dev);
80 fdt_addr_t addr;
81
82 addr = dev_read_addr(dev);
83 if (addr == FDT_ADDR_T_NONE)
84 return -EINVAL;
85 priv->base = map_sysmem(addr, 0x20);
86
87 return 0;
88 }
89
90 static const struct rtc_ops goldfish_rtc_ops = {
91 .get = goldfish_rtc_get,
92 .set = goldfish_rtc_set,
93 };
94
95 static const struct udevice_id goldfish_rtc_of_match[] = {
96 { .compatible = "google,goldfish-rtc", },
97 {},
98 };
99
100 U_BOOT_DRIVER(rtc_goldfish) = {
101 .name = "rtc_goldfish",
102 .id = UCLASS_RTC,
103 .ops = &goldfish_rtc_ops,
104 .probe = goldfish_rtc_probe,
105 .of_match = goldfish_rtc_of_match,
106 .priv_auto = sizeof(struct goldfish_rtc),
107 };
108