1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * PowerNV Real Time Clock.
4  *
5  * Copyright 2011 IBM Corp.
6  */
7 
8 
9 #include <linux/kernel.h>
10 #include <linux/time.h>
11 #include <linux/bcd.h>
12 #include <linux/rtc.h>
13 #include <linux/delay.h>
14 #include <linux/of.h>
15 #include <linux/of_platform.h>
16 #include <linux/platform_device.h>
17 
18 #include <asm/opal.h>
19 #include <asm/firmware.h>
20 #include <asm/machdep.h>
21 
22 static void __init opal_to_tm(u32 y_m_d, u64 h_m_s_ms, struct rtc_time *tm)
23 {
24 	tm->tm_year	= ((bcd2bin(y_m_d >> 24) * 100) +
25 			   bcd2bin((y_m_d >> 16) & 0xff)) - 1900;
26 	tm->tm_mon	= bcd2bin((y_m_d >> 8) & 0xff) - 1;
27 	tm->tm_mday	= bcd2bin(y_m_d & 0xff);
28 	tm->tm_hour	= bcd2bin((h_m_s_ms >> 56) & 0xff);
29 	tm->tm_min	= bcd2bin((h_m_s_ms >> 48) & 0xff);
30 	tm->tm_sec	= bcd2bin((h_m_s_ms >> 40) & 0xff);
31 	tm->tm_wday     = -1;
32 }
33 
34 time64_t __init opal_get_boot_time(void)
35 {
36 	struct rtc_time tm;
37 	u32 y_m_d;
38 	u64 h_m_s_ms;
39 	__be32 __y_m_d;
40 	__be64 __h_m_s_ms;
41 	long rc = OPAL_BUSY;
42 
43 	if (!opal_check_token(OPAL_RTC_READ))
44 		return 0;
45 
46 	while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
47 		rc = opal_rtc_read(&__y_m_d, &__h_m_s_ms);
48 		if (rc == OPAL_BUSY_EVENT) {
49 			mdelay(OPAL_BUSY_DELAY_MS);
50 			opal_poll_events(NULL);
51 		} else if (rc == OPAL_BUSY) {
52 			mdelay(OPAL_BUSY_DELAY_MS);
53 		}
54 	}
55 	if (rc != OPAL_SUCCESS)
56 		return 0;
57 
58 	y_m_d = be32_to_cpu(__y_m_d);
59 	h_m_s_ms = be64_to_cpu(__h_m_s_ms);
60 	opal_to_tm(y_m_d, h_m_s_ms, &tm);
61 	return rtc_tm_to_time64(&tm);
62 }
63 
64 static __init int opal_time_init(void)
65 {
66 	struct platform_device *pdev;
67 	struct device_node *rtc;
68 
69 	rtc = of_find_node_by_path("/ibm,opal/rtc");
70 	if (rtc) {
71 		pdev = of_platform_device_create(rtc, "opal-rtc", NULL);
72 		of_node_put(rtc);
73 	} else {
74 		if (opal_check_token(OPAL_RTC_READ) ||
75 		    opal_check_token(OPAL_READ_TPO))
76 			pdev = platform_device_register_simple("opal-rtc", -1,
77 							       NULL, 0);
78 		else
79 			return -ENODEV;
80 	}
81 
82 	return PTR_ERR_OR_ZERO(pdev);
83 }
84 machine_subsys_initcall(powernv, opal_time_init);
85