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 if (dir) 198 debugfs_remove_recursive(dir); 199 free_irq(OCTEON_IRQ_TIMER0 + TIMER_NUM, 0); 200 } 201 202 module_exit(oct_ilm_module_exit); 203 module_init(oct_ilm_module_init); 204 MODULE_AUTHOR("Venkat Subbiah, Cavium"); 205 MODULE_DESCRIPTION("Measures interrupt latency on Octeon chips."); 206 MODULE_LICENSE("GPL"); 207