1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/kernel.h>
3 #include <linux/time.h>
4 #include <linux/timer.h>
5 #include <linux/init.h>
6 #include <linux/rtc.h>
7 #include <linux/delay.h>
8 #include <linux/ratelimit.h>
9 #include <asm/prom.h>
10 #include <asm/rtas.h>
11 #include <asm/time.h>
12 
13 
14 #define MAX_RTC_WAIT 5000	/* 5 sec */
15 
rtas_get_boot_time(void)16 time64_t __init rtas_get_boot_time(void)
17 {
18 	int ret[8];
19 	int error;
20 	unsigned int wait_time;
21 	u64 max_wait_tb;
22 
23 	max_wait_tb = get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
24 	do {
25 		error = rtas_call(rtas_token("get-time-of-day"), 0, 8, ret);
26 
27 		wait_time = rtas_busy_delay_time(error);
28 		if (wait_time) {
29 			/* This is boot time so we spin. */
30 			udelay(wait_time*1000);
31 		}
32 	} while (wait_time && (get_tb() < max_wait_tb));
33 
34 	if (error != 0) {
35 		printk_ratelimited(KERN_WARNING
36 				   "error: reading the clock failed (%d)\n",
37 				   error);
38 		return 0;
39 	}
40 
41 	return mktime64(ret[0], ret[1], ret[2], ret[3], ret[4], ret[5]);
42 }
43 
44 /* NOTE: get_rtc_time will get an error if executed in interrupt context
45  * and if a delay is needed to read the clock.  In this case we just
46  * silently return without updating rtc_tm.
47  */
rtas_get_rtc_time(struct rtc_time * rtc_tm)48 void rtas_get_rtc_time(struct rtc_time *rtc_tm)
49 {
50         int ret[8];
51 	int error;
52 	unsigned int wait_time;
53 	u64 max_wait_tb;
54 
55 	max_wait_tb = get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
56 	do {
57 		error = rtas_call(rtas_token("get-time-of-day"), 0, 8, ret);
58 
59 		wait_time = rtas_busy_delay_time(error);
60 		if (wait_time) {
61 			if (in_interrupt()) {
62 				memset(rtc_tm, 0, sizeof(struct rtc_time));
63 				printk_ratelimited(KERN_WARNING
64 						   "error: reading clock "
65 						   "would delay interrupt\n");
66 				return;	/* delay not allowed */
67 			}
68 			msleep(wait_time);
69 		}
70 	} while (wait_time && (get_tb() < max_wait_tb));
71 
72 	if (error != 0) {
73 		printk_ratelimited(KERN_WARNING
74 				   "error: reading the clock failed (%d)\n",
75 				   error);
76 		return;
77         }
78 
79 	rtc_tm->tm_sec = ret[5];
80 	rtc_tm->tm_min = ret[4];
81 	rtc_tm->tm_hour = ret[3];
82 	rtc_tm->tm_mday = ret[2];
83 	rtc_tm->tm_mon = ret[1] - 1;
84 	rtc_tm->tm_year = ret[0] - 1900;
85 }
86 
rtas_set_rtc_time(struct rtc_time * tm)87 int rtas_set_rtc_time(struct rtc_time *tm)
88 {
89 	int error, wait_time;
90 	u64 max_wait_tb;
91 
92 	max_wait_tb = get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
93 	do {
94 	        error = rtas_call(rtas_token("set-time-of-day"), 7, 1, NULL,
95 				  tm->tm_year + 1900, tm->tm_mon + 1,
96 				  tm->tm_mday, tm->tm_hour, tm->tm_min,
97 				  tm->tm_sec, 0);
98 
99 		wait_time = rtas_busy_delay_time(error);
100 		if (wait_time) {
101 			if (in_interrupt())
102 				return 1;	/* probably decrementer */
103 			msleep(wait_time);
104 		}
105 	} while (wait_time && (get_tb() < max_wait_tb));
106 
107 	if (error != 0)
108 		printk_ratelimited(KERN_WARNING
109 				   "error: setting the clock failed (%d)\n",
110 				   error);
111 
112         return 0;
113 }
114