kernel/arch/mips/cavium-octeon/oct_ilm.c

   1 #include <linux/fs.h>
   2 #include <linux/interrupt.h>
   3 #include <asm/octeon/octeon.h>
   4 #include <asm/octeon/cvmx-ciu-defs.h>
   5 #include <asm/octeon/cvmx.h>
   6 #include <linux/debugfs.h>
   7 #include <linux/kernel.h>
   8 #include <linux/module.h>
   9 #include <linux/seq_file.h>
  10
  11 #define TIMER_NUM 3
  12
  13 static bool reset_stats;
  14
  15 struct latency_info {
  16         u64 io_interval;
  17         u64 cpu_interval;
  18         u64 timer_start1;
  19         u64 timer_start2;
  20         u64 max_latency;
  21         u64 min_latency;
  22         u64 latency_sum;
  23         u64 average_latency;
  24         u64 interrupt_cnt;
  25 };
  26
  27 static struct latency_info li;
  28 static struct dentry *dir;
  29
  30 static int show_latency(struct seq_file *m, void *v)
  31 {
  32         u64 cpuclk, avg, max, min;
  33         struct latency_info curr_li = li;
  34
  35         cpuclk = octeon_get_clock_rate();
  36
  37         max = (curr_li.max_latency * 1000000000) / cpuclk;
  38         min = (curr_li.min_latency * 1000000000) / cpuclk;
  39         avg = (curr_li.latency_sum * 1000000000) / (cpuclk * curr_li.interrupt_cnt);
  40
  41         seq_printf(m, "cnt: %10lld, avg: %7lld ns, max: %7lld ns, min: %7lld ns\n",
  42                    curr_li.interrupt_cnt, avg, max, min);
  43         return 0;
  44 }
  45
  46 static int oct_ilm_open(struct inode *inode, struct file *file)
  47 {
  48         return single_open(file, show_latency, NULL);
  49 }
  50
  51 static const struct file_operations oct_ilm_ops = {
  52         .open = oct_ilm_open,
  53         .read = seq_read,
  54         .llseek = seq_lseek,
  55         .release = single_release,
  56 };
  57
  58 static int reset_statistics(void *data, u64 value)
  59 {
  60         reset_stats = true;
  61         return 0;
  62 }
  63
  64 DEFINE_SIMPLE_ATTRIBUTE(reset_statistics_ops, NULL, reset_statistics, "%llu\n");
  65
  66 static int init_debufs(void)
  67 {
  68         struct dentry *show_dentry;
  69         dir = debugfs_create_dir("oct_ilm", 0);
  70         if (!dir) {
  71                 pr_err("oct_ilm: failed to create debugfs entry oct_ilm\n");
  72                 return -1;
  73         }
  74
  75         show_dentry = debugfs_create_file("statistics", 0222, dir, NULL,
  76                                           &oct_ilm_ops);
  77         if (!show_dentry) {
  78                 pr_err("oct_ilm: failed to create debugfs entry oct_ilm/statistics\n");
  79                 return -1;
  80         }
  81
  82         show_dentry = debugfs_create_file("reset", 0222, dir, NULL,
  83                                           &reset_statistics_ops);
  84         if (!show_dentry) {
  85                 pr_err("oct_ilm: failed to create debugfs entry oct_ilm/reset\n");
  86                 return -1;
  87         }
  88
  89         return 0;
  90
  91 }
  92
  93 static void init_latency_info(struct latency_info *li, int startup)
  94 {
  95         /* interval in milli seconds after which the interrupt will
  96          * be triggered
  97          */
  98         int interval = 1;
  99
 100         if (startup) {
 101                 /* Calculating by the amounts io clock and cpu clock would
 102                  *  increment in interval amount of ms
 103                  */
 104                 li->io_interval = (octeon_get_io_clock_rate() * interval) / 1000;
 105                 li->cpu_interval = (octeon_get_clock_rate() * interval) / 1000;
 106         }
 107         li->timer_start1 = 0;
 108         li->timer_start2 = 0;
 109         li->max_latency = 0;
 110         li->min_latency = (u64)-1;
 111         li->latency_sum = 0;
 112         li->interrupt_cnt = 0;
 113 }
 114
 115
 116 static void start_timer(int timer, u64 interval)
 117 {
 118         union cvmx_ciu_timx timx;
 119         unsigned long flags;
 120
 121         timx.u64 = 0;
 122         timx.s.one_shot = 1;
 123         timx.s.len = interval;
 124         raw_local_irq_save(flags);
 125         li.timer_start1 = read_c0_cvmcount();
 126         cvmx_write_csr(CVMX_CIU_TIMX(timer), timx.u64);
 127         /* Read it back to force wait until register is written. */
 128         timx.u64 = cvmx_read_csr(CVMX_CIU_TIMX(timer));
 129         li.timer_start2 = read_c0_cvmcount();
 130         raw_local_irq_restore(flags);
 131 }
 132
 133
 134 static irqreturn_t cvm_oct_ciu_timer_interrupt(int cpl, void *dev_id)
 135 {
 136         u64 last_latency;
 137         u64 last_int_cnt;
 138
 139         if (reset_stats) {
 140                 init_latency_info(&li, 0);
 141                 reset_stats = false;
 142         } else {
 143                 last_int_cnt = read_c0_cvmcount();
 144                 last_latency = last_int_cnt - (li.timer_start1 + li.cpu_interval);
 145                 li.interrupt_cnt++;
 146                 li.latency_sum += last_latency;
 147                 if (last_latency > li.max_latency)
 148                         li.max_latency = last_latency;
 149                 if (last_latency < li.min_latency)
 150                         li.min_latency = last_latency;
 151         }
 152         start_timer(TIMER_NUM, li.io_interval);
 153         return IRQ_HANDLED;
 154 }
 155
 156 static void disable_timer(int timer)
 157 {
 158         union cvmx_ciu_timx timx;
 159
 160         timx.s.one_shot = 0;
 161         timx.s.len = 0;
 162         cvmx_write_csr(CVMX_CIU_TIMX(timer), timx.u64);
 163         /* Read it back to force immediate write of timer register*/
 164         timx.u64 = cvmx_read_csr(CVMX_CIU_TIMX(timer));
 165 }
 166
 167 static __init int oct_ilm_module_init(void)
 168 {
 169         int rc;
 170         int irq = OCTEON_IRQ_TIMER0 + TIMER_NUM;
 171
 172         rc = init_debufs();
 173         if (rc) {
 174                 WARN(1, "Could not create debugfs entries");
 175                 return rc;
 176         }
 177
 178         rc = request_irq(irq, cvm_oct_ciu_timer_interrupt, IRQF_NO_THREAD,
 179                          "oct_ilm", 0);
 180         if (rc) {
 181                 WARN(1, "Could not acquire IRQ %d", irq);
 182                 goto err_irq;
 183         }
 184
 185         init_latency_info(&li, 1);
 186         start_timer(TIMER_NUM, li.io_interval);
 187
 188         return 0;
 189 err_irq:
 190         debugfs_remove_recursive(dir);
 191         return rc;
 192 }
 193
 194 static __exit void oct_ilm_module_exit(void)
 195 {
 196         disable_timer(TIMER_NUM);
 197         debugfs_remove_recursive(dir);
 198         free_irq(OCTEON_IRQ_TIMER0 + TIMER_NUM, 0);
 199 }
 200
 201 module_exit(oct_ilm_module_exit);
 202 module_init(oct_ilm_module_init);
 203 MODULE_AUTHOR("Venkat Subbiah, Cavium");
 204 MODULE_DESCRIPTION("Measures interrupt latency on Octeon chips.");
 205 MODULE_LICENSE("GPL");