1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2008-2009 Manuel Lauss <manuel.lauss@gmail.com>
4 *
5 * Previous incarnations were:
6 * Copyright (C) 2001, 2006, 2008 MontaVista Software, <source@mvista.com>
7 * Copied and modified Carsten Langgaard's time.c
8 *
9 * Carsten Langgaard, carstenl@mips.com
10 * Copyright (C) 1999,2000 MIPS Technologies, Inc. All rights reserved.
11 *
12 * ########################################################################
13 *
14 * ########################################################################
15 *
16 * Clocksource/event using the 32.768kHz-clocked Counter1 ('RTC' in the
17 * databooks). Firmware/Board init code must enable the counters in the
18 * counter control register, otherwise the CP0 counter clocksource/event
19 * will be installed instead (and use of 'wait' instruction is prohibited).
20 */
21
22 #include <linux/clockchips.h>
23 #include <linux/clocksource.h>
24 #include <linux/interrupt.h>
25 #include <linux/spinlock.h>
26
27 #include <asm/idle.h>
28 #include <asm/processor.h>
29 #include <asm/time.h>
30 #include <asm/mach-au1x00/au1000.h>
31
32 /* 32kHz clock enabled and detected */
33 #define CNTR_OK (SYS_CNTRL_E0 | SYS_CNTRL_32S)
34
35 static u64 au1x_counter1_read(struct clocksource *cs)
36 {
37 return alchemy_rdsys(AU1000_SYS_RTCREAD);
38 }
39
40 static struct clocksource au1x_counter1_clocksource = {
41 .name = "alchemy-counter1",
42 .read = au1x_counter1_read,
43 .mask = CLOCKSOURCE_MASK(32),
44 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
45 .rating = 1500,
46 };
47
48 static int au1x_rtcmatch2_set_next_event(unsigned long delta,
49 struct clock_event_device *cd)
50 {
51 delta += alchemy_rdsys(AU1000_SYS_RTCREAD);
52 /* wait for register access */
53 while (alchemy_rdsys(AU1000_SYS_CNTRCTRL) & SYS_CNTRL_M21)
54 ;
55 alchemy_wrsys(delta, AU1000_SYS_RTCMATCH2);
56
57 return 0;
58 }
59
60 static irqreturn_t au1x_rtcmatch2_irq(int irq, void *dev_id)
61 {
62 struct clock_event_device *cd = dev_id;
63 cd->event_handler(cd);
64 return IRQ_HANDLED;
65 }
66
67 static struct clock_event_device au1x_rtcmatch2_clockdev = {
68 .name = "rtcmatch2",
69 .features = CLOCK_EVT_FEAT_ONESHOT,
70 .rating = 1500,
71 .set_next_event = au1x_rtcmatch2_set_next_event,
72 .cpumask = cpu_possible_mask,
73 };
74
75 static int __init alchemy_time_init(unsigned int m2int)
76 {
77 struct clock_event_device *cd = &au1x_rtcmatch2_clockdev;
78 unsigned long t;
79
80 au1x_rtcmatch2_clockdev.irq = m2int;
81
82 /* Check if firmware (YAMON, ...) has enabled 32kHz and clock
83 * has been detected. If so install the rtcmatch2 clocksource,
84 * otherwise don't bother. Note that both bits being set is by
85 * no means a definite guarantee that the counters actually work
86 * (the 32S bit seems to be stuck set to 1 once a single clock-
87 * edge is detected, hence the timeouts).
88 */
89 if (CNTR_OK != (alchemy_rdsys(AU1000_SYS_CNTRCTRL) & CNTR_OK))
90 goto cntr_err;
91
92 /*
93 * setup counter 1 (RTC) to tick at full speed
94 */
95 t = 0xffffff;
96 while ((alchemy_rdsys(AU1000_SYS_CNTRCTRL) & SYS_CNTRL_T1S) && --t)
97 asm volatile ("nop");
98 if (!t)
99 goto cntr_err;
100
101 alchemy_wrsys(0, AU1000_SYS_RTCTRIM); /* 32.768 kHz */
102
103 t = 0xffffff;
104 while ((alchemy_rdsys(AU1000_SYS_CNTRCTRL) & SYS_CNTRL_C1S) && --t)
105 asm volatile ("nop");
106 if (!t)
107 goto cntr_err;
108 alchemy_wrsys(0, AU1000_SYS_RTCWRITE);
109
110 t = 0xffffff;
111 while ((alchemy_rdsys(AU1000_SYS_CNTRCTRL) & SYS_CNTRL_C1S) && --t)
112 asm volatile ("nop");
113 if (!t)
114 goto cntr_err;
115
116 /* register counter1 clocksource and event device */
117 clocksource_register_hz(&au1x_counter1_clocksource, 32768);
118
119 cd->shift = 32;
120 cd->mult = div_sc(32768, NSEC_PER_SEC, cd->shift);
121 cd->max_delta_ns = clockevent_delta2ns(0xffffffff, cd);
122 cd->max_delta_ticks = 0xffffffff;
123 cd->min_delta_ns = clockevent_delta2ns(9, cd);
124 cd->min_delta_ticks = 9; /* ~0.28ms */
125 clockevents_register_device(cd);
126 if (request_irq(m2int, au1x_rtcmatch2_irq, IRQF_TIMER, "timer",
127 &au1x_rtcmatch2_clockdev))
128 pr_err("Failed to register timer interrupt\n");
129
130 printk(KERN_INFO "Alchemy clocksource installed\n");
131
132 return 0;
133
134 cntr_err:
135 return -1;
136 }
137
138 static int alchemy_m2inttab[] __initdata = {
139 AU1000_RTC_MATCH2_INT,
140 AU1500_RTC_MATCH2_INT,
141 AU1100_RTC_MATCH2_INT,
142 AU1550_RTC_MATCH2_INT,
143 AU1200_RTC_MATCH2_INT,
144 AU1300_RTC_MATCH2_INT,
145 };
146
147 void __init plat_time_init(void)
148 {
149 int t;
150
151 t = alchemy_get_cputype();
152 if (t == ALCHEMY_CPU_UNKNOWN ||
153 alchemy_time_init(alchemy_m2inttab[t]))
154 cpu_wait = NULL; /* wait doesn't work with r4k timer */
155 }
156
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