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
15time64_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(usec: 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(year: ret[0], mon: ret[1], day: ret[2], hour: ret[3], min: ret[4], sec: 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 */
47void 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(msecs: 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
86int 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(msecs: 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

source code of linux/arch/powerpc/kernel/rtas-rtc.c