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