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