From: Venkat Subbiah <venkat.subbiah@xxxxxxxxxx>
Signed-off-by: Venkat Subbiah <venkat.subbiah@xxxxxxxxxx>
[Rewrote timeing calculations]
Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
---
arch/mips/cavium-octeon/Kconfig | 9 ++
arch/mips/cavium-octeon/Makefile | 1 +
arch/mips/cavium-octeon/oct_ilm.c | 206
+++++++++++++++++++++++++++++++++++++
3 files changed, 216 insertions(+)
create mode 100644 arch/mips/cavium-octeon/oct_ilm.c
diff --git a/arch/mips/cavium-octeon/Kconfig
b/arch/mips/cavium-octeon/Kconfig
index 2f4f6d5..75a6df7 100644
--- a/arch/mips/cavium-octeon/Kconfig
+++ b/arch/mips/cavium-octeon/Kconfig
@@ -94,4 +94,13 @@ config SWIOTLB
select NEED_SG_DMA_LENGTH
+config OCTEON_ILM
+ tristate "Module to measure interrupt latency using Octeon CIU
Timer"
+ help
+ This driver is a module to measure interrupt latency using the
+ the CIU Timers on Octeon.
+
+ To compile this driver as a module, choose M here. The module
+ will be called octeon-ilm
+
endif # CPU_CAVIUM_OCTEON
diff --git a/arch/mips/cavium-octeon/Makefile
b/arch/mips/cavium-octeon/Makefile
index bc96e29..614db10 100644
--- a/arch/mips/cavium-octeon/Makefile
+++ b/arch/mips/cavium-octeon/Makefile
@@ -18,6 +18,7 @@ obj-y += octeon-memcpy.o
obj-y += executive/
obj-$(CONFIG_SMP) += smp.o
+obj-$(CONFIG_OCTEON_ILM) += oct_ilm.o
DTS_FILES = octeon_3xxx.dts octeon_68xx.dts
DTB_FILES = $(patsubst %.dts, %.dtb, $(DTS_FILES))
diff --git a/arch/mips/cavium-octeon/oct_ilm.c
b/arch/mips/cavium-octeon/oct_ilm.c
new file mode 100644
index 0000000..71b213d
--- /dev/null
+++ b/arch/mips/cavium-octeon/oct_ilm.c
@@ -0,0 +1,206 @@
+#include <linux/fs.h>
+#include <linux/interrupt.h>
+#include <asm/octeon/octeon.h>
+#include <asm/octeon/cvmx-ciu-defs.h>
+#include <asm/octeon/cvmx.h>
+#include <linux/debugfs.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+
+#define TIMER_NUM 3
+
+static bool reset_stats;
+
+struct latency_info {
+ u64 io_interval;
+ u64 cpu_interval;
+ u64 timer_start1;
+ u64 timer_start2;
+ u64 max_latency;
+ u64 min_latency;
+ u64 latency_sum;
+ u64 average_latency;
+ u64 interrupt_cnt;
+};
+
+static struct latency_info li;
+static struct dentry *dir;
+
+static int show_latency(struct seq_file *m, void *v)
+{
+ u64 cpuclk, avg, max, min;
+ struct latency_info curr_li = li;
+
+ cpuclk = octeon_get_clock_rate();
+
+ max = (curr_li.max_latency * 1000000000) / cpuclk;
+ min = (curr_li.min_latency * 1000000000) / cpuclk;
+ avg = (curr_li.latency_sum * 1000000000) / (cpuclk *
curr_li.interrupt_cnt);
+
+ seq_printf(m, "cnt: %10lld, avg: %7lld ns, max: %7lld ns, min:
%7lld ns\n",
+ curr_li.interrupt_cnt, avg, max, min);
+ return 0;
+}
+
+static int oct_ilm_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, show_latency, NULL);
+}
+
+static const struct file_operations oct_ilm_ops = {
+ .open = oct_ilm_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int reset_statistics(void *data, u64 value)
+{
+ reset_stats = true;
+ return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(reset_statistics_ops, NULL, reset_statistics,
"%llu\n");
+
+static int init_debufs(void)
+{
+ struct dentry *show_dentry;
+ dir = debugfs_create_dir("oct_ilm", 0);
+ if (!dir) {
+ pr_err("oct_ilm: failed to create debugfs entry oct_ilm\n");
+ return -1;
+ }
+
+ show_dentry = debugfs_create_file("statistics", 0222, dir, NULL,
+ &oct_ilm_ops);
+ if (!show_dentry) {
+ pr_err("oct_ilm: failed to create debugfs entry
oct_ilm/statistics\n");
+ return -1;
+ }
+
+ show_dentry = debugfs_create_file("reset", 0222, dir, NULL,
+ &reset_statistics_ops);
+ if (!show_dentry) {
+ pr_err("oct_ilm: failed to create debugfs entry
oct_ilm/reset\n");
+ return -1;
+ }
+
+ return 0;
+
+}
+
+static void init_latency_info(struct latency_info *li, int startup)
+{
+ /* interval in milli seconds after which the interrupt will
+ * be triggered
+ */
+ int interval = 1;
+
+ if (startup) {
+ /* Calculating by the amounts io clock and cpu clock would
+ * increment in interval amount of ms
+ */
+ li->io_interval = (octeon_get_io_clock_rate() * interval) /
1000;
+ li->cpu_interval = (octeon_get_clock_rate() * interval) / 1000;
+ }
+ li->timer_start1 = 0;
+ li->timer_start2 = 0;
+ li->max_latency = 0;
+ li->min_latency = (u64)-1;
+ li->latency_sum = 0;
+ li->interrupt_cnt = 0;
+}
+
+
+static void start_timer(int timer, u64 interval)
+{
+ union cvmx_ciu_timx timx;
+ unsigned long flags;
+
+ timx.u64 = 0;
+ timx.s.one_shot = 1;
+ timx.s.len = interval;
+ raw_local_irq_save(flags);
+ li.timer_start1 = read_c0_cvmcount();
+ cvmx_write_csr(CVMX_CIU_TIMX(timer), timx.u64);
+ /* Read it back to force wait until register is written. */
+ timx.u64 = cvmx_read_csr(CVMX_CIU_TIMX(timer));
+ li.timer_start2 = read_c0_cvmcount();
+ raw_local_irq_restore(flags);
+}
+
+
+static irqreturn_t cvm_oct_ciu_timer_interrupt(int cpl, void *dev_id)
+{
+ u64 last_latency;
+ u64 last_int_cnt;
+
+ if (reset_stats) {
+ init_latency_info(&li, 0);
+ reset_stats = false;
+ } else {
+ last_int_cnt = read_c0_cvmcount();
+ last_latency = last_int_cnt - (li.timer_start1 +
li.cpu_interval);
+ li.interrupt_cnt++;
+ li.latency_sum += last_latency;
+ if (last_latency > li.max_latency)
+ li.max_latency = last_latency;
+ if (last_latency < li.min_latency)
+ li.min_latency = last_latency;
+ }
+ start_timer(TIMER_NUM, li.io_interval);
+ return IRQ_HANDLED;
+}
+
+static void disable_timer(int timer)
+{
+ union cvmx_ciu_timx timx;
+
+ timx.s.one_shot = 0;
+ timx.s.len = 0;
+ cvmx_write_csr(CVMX_CIU_TIMX(timer), timx.u64);
+ /* Read it back to force immediate write of timer register*/
+ timx.u64 = cvmx_read_csr(CVMX_CIU_TIMX(timer));
+}
+
+static __init int oct_ilm_module_init(void)
+{
+ int rc;
+ int irq = OCTEON_IRQ_TIMER0 + TIMER_NUM;
+
+ rc = init_debufs();
+ if (rc) {
+ WARN(1, "Could not create debugfs entries");
+ return rc;
+ }
+
+ rc = request_irq(irq, cvm_oct_ciu_timer_interrupt, IRQF_NO_THREAD,
+ "oct_ilm", 0);
+ if (rc) {
+ WARN(1, "Could not acquire IRQ %d", irq);
+ goto err_irq;
+ }
+
+ init_latency_info(&li, 1);
+ start_timer(TIMER_NUM, li.io_interval);
+
+ return 0;
+err_irq:
+ debugfs_remove_recursive(dir);
+ return rc;
+}
+
+static __exit void oct_ilm_module_exit(void)
+{
+ disable_timer(TIMER_NUM);
+ if (dir)
+ debugfs_remove_recursive(dir);
+ free_irq(OCTEON_IRQ_TIMER0 + TIMER_NUM, 0);
+}
+
+module_exit(oct_ilm_module_exit);
+module_init(oct_ilm_module_init);
+MODULE_AUTHOR("Venkat Subbiah, Cavium");
+MODULE_DESCRIPTION("Measures interrupt latency on Octeon chips.");
+MODULE_LICENSE("GPL");
