1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/fs.h>
3 #include <linux/interrupt.h>
4 #include <asm/octeon/octeon.h>
5 #include <asm/octeon/cvmx-ciu-defs.h>
6 #include <asm/octeon/cvmx.h>
7 #include <linux/debugfs.h>
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/seq_file.h>
11
12 #define TIMER_NUM 3
13
14 static bool reset_stats;
15
16 struct latency_info {
17 u64 io_interval;
18 u64 cpu_interval;
19 u64 timer_start1;
20 u64 timer_start2;
21 u64 max_latency;
22 u64 min_latency;
23 u64 latency_sum;
24 u64 average_latency;
25 u64 interrupt_cnt;
26 };
27
28 static struct latency_info li;
29 static struct dentry *dir;
30
31 static int oct_ilm_show(struct seq_file *m, void *v)
32 {
33 u64 cpuclk, avg, max, min;
34 struct latency_info curr_li = li;
35
36 cpuclk = octeon_get_clock_rate();
37
38 max = (curr_li.max_latency * 1000000000) / cpuclk;
39 min = (curr_li.min_latency * 1000000000) / cpuclk;
40 avg = (curr_li.latency_sum * 1000000000) / (cpuclk * curr_li.interrupt_cnt);
41
42 seq_printf(m, "cnt: %10lld, avg: %7lld ns, max: %7lld ns, min: %7lld ns\n",
43 curr_li.interrupt_cnt, avg, max, min);
44 return 0;
45 }
46 DEFINE_SHOW_ATTRIBUTE(oct_ilm);
47
48 static int reset_statistics(void *data, u64 value)
49 {
50 reset_stats = true;
51 return 0;
52 }
53
54 DEFINE_DEBUGFS_ATTRIBUTE(reset_statistics_ops, NULL, reset_statistics, "%llu\n");
55
56 static void init_debugfs(void)
57 {
58 dir = debugfs_create_dir("oct_ilm", 0);
59 debugfs_create_file("statistics", 0222, dir, NULL, &oct_ilm_fops);
60 debugfs_create_file("reset", 0222, dir, NULL, &reset_statistics_ops);
61 }
62
63 static void init_latency_info(struct latency_info *li, int startup)
64 {
65 /* interval in milli seconds after which the interrupt will
66 * be triggered
67 */
68 int interval = 1;
69
70 if (startup) {
71 /* Calculating by the amounts io clock and cpu clock would
72 * increment in interval amount of ms
73 */
74 li->io_interval = (octeon_get_io_clock_rate() * interval) / 1000;
75 li->cpu_interval = (octeon_get_clock_rate() * interval) / 1000;
76 }
77 li->timer_start1 = 0;
78 li->timer_start2 = 0;
79 li->max_latency = 0;
80 li->min_latency = (u64)-1;
81 li->latency_sum = 0;
82 li->interrupt_cnt = 0;
83 }
84
85
86 static void start_timer(int timer, u64 interval)
87 {
88 union cvmx_ciu_timx timx;
89 unsigned long flags;
90
91 timx.u64 = 0;
92 timx.s.one_shot = 1;
93 timx.s.len = interval;
94 raw_local_irq_save(flags);
95 li.timer_start1 = read_c0_cvmcount();
96 cvmx_write_csr(CVMX_CIU_TIMX(timer), timx.u64);
97 /* Read it back to force wait until register is written. */
98 timx.u64 = cvmx_read_csr(CVMX_CIU_TIMX(timer));
99 li.timer_start2 = read_c0_cvmcount();
100 raw_local_irq_restore(flags);
101 }
102
103
104 static irqreturn_t cvm_oct_ciu_timer_interrupt(int cpl, void *dev_id)
105 {
106 u64 last_latency;
107 u64 last_int_cnt;
108
109 if (reset_stats) {
110 init_latency_info(&li, 0);
111 reset_stats = false;
112 } else {
113 last_int_cnt = read_c0_cvmcount();
114 last_latency = last_int_cnt - (li.timer_start1 + li.cpu_interval);
115 li.interrupt_cnt++;
116 li.latency_sum += last_latency;
117 if (last_latency > li.max_latency)
118 li.max_latency = last_latency;
119 if (last_latency < li.min_latency)
120 li.min_latency = last_latency;
121 }
122 start_timer(TIMER_NUM, li.io_interval);
123 return IRQ_HANDLED;
124 }
125
126 static void disable_timer(int timer)
127 {
128 union cvmx_ciu_timx timx;
129
130 timx.s.one_shot = 0;
131 timx.s.len = 0;
132 cvmx_write_csr(CVMX_CIU_TIMX(timer), timx.u64);
133 /* Read it back to force immediate write of timer register*/
134 timx.u64 = cvmx_read_csr(CVMX_CIU_TIMX(timer));
135 }
136
137 static __init int oct_ilm_module_init(void)
138 {
139 int rc;
140 int irq = OCTEON_IRQ_TIMER0 + TIMER_NUM;
141
142 init_debugfs();
143
144 rc = request_irq(irq, cvm_oct_ciu_timer_interrupt, IRQF_NO_THREAD,
145 "oct_ilm", 0);
146 if (rc) {
147 WARN(1, "Could not acquire IRQ %d", irq);
148 goto err_irq;
149 }
150
151 init_latency_info(&li, 1);
152 start_timer(TIMER_NUM, li.io_interval);
153
154 return 0;
155 err_irq:
156 debugfs_remove_recursive(dir);
157 return rc;
158 }
159
160 static __exit void oct_ilm_module_exit(void)
161 {
162 disable_timer(TIMER_NUM);
163 debugfs_remove_recursive(dir);
164 free_irq(OCTEON_IRQ_TIMER0 + TIMER_NUM, 0);
165 }
166
167 module_exit(oct_ilm_module_exit);
168 module_init(oct_ilm_module_init);
169 MODULE_AUTHOR("Venkat Subbiah, Cavium");
170 MODULE_DESCRIPTION("Measures interrupt latency on Octeon chips.");
171 MODULE_LICENSE("GPL");
172
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