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1// SPDX-License-Identifier: GPL-2.0
2#include <linux/types.h>
3#include <linux/i8253.h>
4#include <linux/interrupt.h>
5#include <linux/irq.h>
6#include <linux/smp.h>
7#include <linux/time.h>
8#include <linux/clockchips.h>
9
10#include <asm/sni.h>
11#include <asm/time.h>
12
13#define SNI_CLOCK_TICK_RATE 3686400
14#define SNI_COUNTER2_DIV 64
15#define SNI_COUNTER0_DIV ((SNI_CLOCK_TICK_RATE / SNI_COUNTER2_DIV) / HZ)
16
17static int a20r_set_periodic(struct clock_event_device *evt)
18{
19 *(volatile u8 *)(A20R_PT_CLOCK_BASE + 12) = 0x34;
20 wmb();
21 *(volatile u8 *)(A20R_PT_CLOCK_BASE + 0) = SNI_COUNTER0_DIV & 0xff;
22 wmb();
23 *(volatile u8 *)(A20R_PT_CLOCK_BASE + 0) = SNI_COUNTER0_DIV >> 8;
24 wmb();
25
26 *(volatile u8 *)(A20R_PT_CLOCK_BASE + 12) = 0xb4;
27 wmb();
28 *(volatile u8 *)(A20R_PT_CLOCK_BASE + 8) = SNI_COUNTER2_DIV & 0xff;
29 wmb();
30 *(volatile u8 *)(A20R_PT_CLOCK_BASE + 8) = SNI_COUNTER2_DIV >> 8;
31 wmb();
32 return 0;
33}
34
35static struct clock_event_device a20r_clockevent_device = {
36 .name = "a20r-timer",
37 .features = CLOCK_EVT_FEAT_PERIODIC,
38
39 /* .mult, .shift, .max_delta_ns and .min_delta_ns left uninitialized */
40
41 .rating = 300,
42 .irq = SNI_A20R_IRQ_TIMER,
43 .set_state_periodic = a20r_set_periodic,
44};
45
46static irqreturn_t a20r_interrupt(int irq, void *dev_id)
47{
48 struct clock_event_device *cd = dev_id;
49
50 *(volatile u8 *)A20R_PT_TIM0_ACK = 0;
51 wmb();
52
53 cd->event_handler(cd);
54
55 return IRQ_HANDLED;
56}
57
58/*
59 * a20r platform uses 2 counters to divide the input frequency.
60 * Counter 2 output is connected to Counter 0 & 1 input.
61 */
62static void __init sni_a20r_timer_setup(void)
63{
64 struct clock_event_device *cd = &a20r_clockevent_device;
65 unsigned int cpu = smp_processor_id();
66
67 cd->cpumask = cpumask_of(cpu);
68 clockevents_register_device(cd);
69 if (request_irq(SNI_A20R_IRQ_TIMER, a20r_interrupt,
70 IRQF_PERCPU | IRQF_TIMER, "a20r-timer", cd))
71 pr_err("Failed to register a20r-timer interrupt\n");
72}
73
74#define SNI_8254_TICK_RATE 1193182UL
75
76#define SNI_8254_TCSAMP_COUNTER ((SNI_8254_TICK_RATE / HZ) + 255)
77
78static __init unsigned long dosample(void)
79{
80 u32 ct0, ct1;
81 volatile u8 msb;
82
83 /* Start the counter. */
84 outb_p(0x34, 0x43);
85 outb_p(SNI_8254_TCSAMP_COUNTER & 0xff, 0x40);
86 outb(SNI_8254_TCSAMP_COUNTER >> 8, 0x40);
87
88 /* Get initial counter invariant */
89 ct0 = read_c0_count();
90
91 /* Latch and spin until top byte of counter0 is zero */
92 do {
93 outb(0x00, 0x43);
94 (void) inb(0x40);
95 msb = inb(0x40);
96 ct1 = read_c0_count();
97 } while (msb);
98
99 /* Stop the counter. */
100 outb(0x38, 0x43);
101 /*
102 * Return the difference, this is how far the r4k counter increments
103 * for every 1/HZ seconds. We round off the nearest 1 MHz of master
104 * clock (= 1000000 / HZ / 2).
105 */
106 /*return (ct1 - ct0 + (500000/HZ/2)) / (500000/HZ) * (500000/HZ);*/
107 return (ct1 - ct0) / (500000/HZ) * (500000/HZ);
108}
109
110/*
111 * Here we need to calibrate the cycle counter to at least be close.
112 */
113void __init plat_time_init(void)
114{
115 unsigned long r4k_ticks[3];
116 unsigned long r4k_tick;
117
118 /*
119 * Figure out the r4k offset, the algorithm is very simple and works in
120 * _all_ cases as long as the 8254 counter register itself works ok (as
121 * an interrupt driving timer it does not because of bug, this is why
122 * we are using the onchip r4k counter/compare register to serve this
123 * purpose, but for r4k_offset calculation it will work ok for us).
124 * There are other very complicated ways of performing this calculation
125 * but this one works just fine so I am not going to futz around. ;-)
126 */
127 printk(KERN_INFO "Calibrating system timer... ");
128 dosample(); /* Prime cache. */
129 dosample(); /* Prime cache. */
130 /* Zero is NOT an option. */
131 do {
132 r4k_ticks[0] = dosample();
133 } while (!r4k_ticks[0]);
134 do {
135 r4k_ticks[1] = dosample();
136 } while (!r4k_ticks[1]);
137
138 if (r4k_ticks[0] != r4k_ticks[1]) {
139 printk("warning: timer counts differ, retrying... ");
140 r4k_ticks[2] = dosample();
141 if (r4k_ticks[2] == r4k_ticks[0]
142 || r4k_ticks[2] == r4k_ticks[1])
143 r4k_tick = r4k_ticks[2];
144 else {
145 printk("disagreement, using average... ");
146 r4k_tick = (r4k_ticks[0] + r4k_ticks[1]
147 + r4k_ticks[2]) / 3;
148 }
149 } else
150 r4k_tick = r4k_ticks[0];
151
152 printk("%d [%d.%04d MHz CPU]\n", (int) r4k_tick,
153 (int) (r4k_tick / (500000 / HZ)),
154 (int) (r4k_tick % (500000 / HZ)));
155
156 mips_hpt_frequency = r4k_tick * HZ;
157
158 switch (sni_brd_type) {
159 case SNI_BRD_10:
160 case SNI_BRD_10NEW:
161 case SNI_BRD_TOWER_OASIC:
162 case SNI_BRD_MINITOWER:
163 sni_a20r_timer_setup();
164 break;
165 }
166 setup_pit_timer();
167}
1#include <linux/types.h>
2#include <linux/i8253.h>
3#include <linux/interrupt.h>
4#include <linux/irq.h>
5#include <linux/smp.h>
6#include <linux/time.h>
7#include <linux/clockchips.h>
8
9#include <asm/sni.h>
10#include <asm/time.h>
11
12#define SNI_CLOCK_TICK_RATE 3686400
13#define SNI_COUNTER2_DIV 64
14#define SNI_COUNTER0_DIV ((SNI_CLOCK_TICK_RATE / SNI_COUNTER2_DIV) / HZ)
15
16static int a20r_set_periodic(struct clock_event_device *evt)
17{
18 *(volatile u8 *)(A20R_PT_CLOCK_BASE + 12) = 0x34;
19 wmb();
20 *(volatile u8 *)(A20R_PT_CLOCK_BASE + 0) = SNI_COUNTER0_DIV;
21 wmb();
22 *(volatile u8 *)(A20R_PT_CLOCK_BASE + 0) = SNI_COUNTER0_DIV >> 8;
23 wmb();
24
25 *(volatile u8 *)(A20R_PT_CLOCK_BASE + 12) = 0xb4;
26 wmb();
27 *(volatile u8 *)(A20R_PT_CLOCK_BASE + 8) = SNI_COUNTER2_DIV;
28 wmb();
29 *(volatile u8 *)(A20R_PT_CLOCK_BASE + 8) = SNI_COUNTER2_DIV >> 8;
30 wmb();
31 return 0;
32}
33
34static struct clock_event_device a20r_clockevent_device = {
35 .name = "a20r-timer",
36 .features = CLOCK_EVT_FEAT_PERIODIC,
37
38 /* .mult, .shift, .max_delta_ns and .min_delta_ns left uninitialized */
39
40 .rating = 300,
41 .irq = SNI_A20R_IRQ_TIMER,
42 .set_state_periodic = a20r_set_periodic,
43};
44
45static irqreturn_t a20r_interrupt(int irq, void *dev_id)
46{
47 struct clock_event_device *cd = dev_id;
48
49 *(volatile u8 *)A20R_PT_TIM0_ACK = 0;
50 wmb();
51
52 cd->event_handler(cd);
53
54 return IRQ_HANDLED;
55}
56
57static struct irqaction a20r_irqaction = {
58 .handler = a20r_interrupt,
59 .flags = IRQF_PERCPU | IRQF_TIMER,
60 .name = "a20r-timer",
61};
62
63/*
64 * a20r platform uses 2 counters to divide the input frequency.
65 * Counter 2 output is connected to Counter 0 & 1 input.
66 */
67static void __init sni_a20r_timer_setup(void)
68{
69 struct clock_event_device *cd = &a20r_clockevent_device;
70 struct irqaction *action = &a20r_irqaction;
71 unsigned int cpu = smp_processor_id();
72
73 cd->cpumask = cpumask_of(cpu);
74 clockevents_register_device(cd);
75 action->dev_id = cd;
76 setup_irq(SNI_A20R_IRQ_TIMER, &a20r_irqaction);
77}
78
79#define SNI_8254_TICK_RATE 1193182UL
80
81#define SNI_8254_TCSAMP_COUNTER ((SNI_8254_TICK_RATE / HZ) + 255)
82
83static __init unsigned long dosample(void)
84{
85 u32 ct0, ct1;
86 volatile u8 msb;
87
88 /* Start the counter. */
89 outb_p(0x34, 0x43);
90 outb_p(SNI_8254_TCSAMP_COUNTER & 0xff, 0x40);
91 outb(SNI_8254_TCSAMP_COUNTER >> 8, 0x40);
92
93 /* Get initial counter invariant */
94 ct0 = read_c0_count();
95
96 /* Latch and spin until top byte of counter0 is zero */
97 do {
98 outb(0x00, 0x43);
99 (void) inb(0x40);
100 msb = inb(0x40);
101 ct1 = read_c0_count();
102 } while (msb);
103
104 /* Stop the counter. */
105 outb(0x38, 0x43);
106 /*
107 * Return the difference, this is how far the r4k counter increments
108 * for every 1/HZ seconds. We round off the nearest 1 MHz of master
109 * clock (= 1000000 / HZ / 2).
110 */
111 /*return (ct1 - ct0 + (500000/HZ/2)) / (500000/HZ) * (500000/HZ);*/
112 return (ct1 - ct0) / (500000/HZ) * (500000/HZ);
113}
114
115/*
116 * Here we need to calibrate the cycle counter to at least be close.
117 */
118void __init plat_time_init(void)
119{
120 unsigned long r4k_ticks[3];
121 unsigned long r4k_tick;
122
123 /*
124 * Figure out the r4k offset, the algorithm is very simple and works in
125 * _all_ cases as long as the 8254 counter register itself works ok (as
126 * an interrupt driving timer it does not because of bug, this is why
127 * we are using the onchip r4k counter/compare register to serve this
128 * purpose, but for r4k_offset calculation it will work ok for us).
129 * There are other very complicated ways of performing this calculation
130 * but this one works just fine so I am not going to futz around. ;-)
131 */
132 printk(KERN_INFO "Calibrating system timer... ");
133 dosample(); /* Prime cache. */
134 dosample(); /* Prime cache. */
135 /* Zero is NOT an option. */
136 do {
137 r4k_ticks[0] = dosample();
138 } while (!r4k_ticks[0]);
139 do {
140 r4k_ticks[1] = dosample();
141 } while (!r4k_ticks[1]);
142
143 if (r4k_ticks[0] != r4k_ticks[1]) {
144 printk("warning: timer counts differ, retrying... ");
145 r4k_ticks[2] = dosample();
146 if (r4k_ticks[2] == r4k_ticks[0]
147 || r4k_ticks[2] == r4k_ticks[1])
148 r4k_tick = r4k_ticks[2];
149 else {
150 printk("disagreement, using average... ");
151 r4k_tick = (r4k_ticks[0] + r4k_ticks[1]
152 + r4k_ticks[2]) / 3;
153 }
154 } else
155 r4k_tick = r4k_ticks[0];
156
157 printk("%d [%d.%04d MHz CPU]\n", (int) r4k_tick,
158 (int) (r4k_tick / (500000 / HZ)),
159 (int) (r4k_tick % (500000 / HZ)));
160
161 mips_hpt_frequency = r4k_tick * HZ;
162
163 switch (sni_brd_type) {
164 case SNI_BRD_10:
165 case SNI_BRD_10NEW:
166 case SNI_BRD_TOWER_OASIC:
167 case SNI_BRD_MINITOWER:
168 sni_a20r_timer_setup();
169 break;
170 }
171 setup_pit_timer();
172}
173
174void read_persistent_clock(struct timespec *ts)
175{
176 ts->tv_sec = -1;
177 ts->tv_nsec = 0;
178}