[T106][ZXW-22]7520V3SCV2.01.01.02P42U09_VEC_V0.8_AP_VEC origin source commit
Change-Id: Ic6e05d89ecd62fc34f82b23dcf306c93764aec4b
diff --git a/ap/os/linux/linux-3.4.x/init/calibrate.c b/ap/os/linux/linux-3.4.x/init/calibrate.c
new file mode 100644
index 0000000..fda0a7b
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/init/calibrate.c
@@ -0,0 +1,301 @@
+/* calibrate.c: default delay calibration
+ *
+ * Excised from init/main.c
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ */
+
+#include <linux/jiffies.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/timex.h>
+#include <linux/smp.h>
+#include <linux/percpu.h>
+
+unsigned long lpj_fine;
+unsigned long preset_lpj;
+static int __init lpj_setup(char *str)
+{
+ preset_lpj = simple_strtoul(str,NULL,0);
+ return 1;
+}
+
+__setup("lpj=", lpj_setup);
+
+#ifdef ARCH_HAS_READ_CURRENT_TIMER
+
+/* This routine uses the read_current_timer() routine and gets the
+ * loops per jiffy directly, instead of guessing it using delay().
+ * Also, this code tries to handle non-maskable asynchronous events
+ * (like SMIs)
+ */
+#define DELAY_CALIBRATION_TICKS ((HZ < 100) ? 1 : (HZ/100))
+#define MAX_DIRECT_CALIBRATION_RETRIES 5
+
+static unsigned long __cpuinit calibrate_delay_direct(void)
+{
+ unsigned long pre_start, start, post_start;
+ unsigned long pre_end, end, post_end;
+ unsigned long start_jiffies;
+ unsigned long timer_rate_min, timer_rate_max;
+ unsigned long good_timer_sum = 0;
+ unsigned long good_timer_count = 0;
+ unsigned long measured_times[MAX_DIRECT_CALIBRATION_RETRIES];
+ int max = -1; /* index of measured_times with max/min values or not set */
+ int min = -1;
+ int i;
+
+ if (read_current_timer(&pre_start) < 0 )
+ return 0;
+
+ /*
+ * A simple loop like
+ * while ( jiffies < start_jiffies+1)
+ * start = read_current_timer();
+ * will not do. As we don't really know whether jiffy switch
+ * happened first or timer_value was read first. And some asynchronous
+ * event can happen between these two events introducing errors in lpj.
+ *
+ * So, we do
+ * 1. pre_start <- When we are sure that jiffy switch hasn't happened
+ * 2. check jiffy switch
+ * 3. start <- timer value before or after jiffy switch
+ * 4. post_start <- When we are sure that jiffy switch has happened
+ *
+ * Note, we don't know anything about order of 2 and 3.
+ * Now, by looking at post_start and pre_start difference, we can
+ * check whether any asynchronous event happened or not
+ */
+
+ for (i = 0; i < MAX_DIRECT_CALIBRATION_RETRIES; i++) {
+ pre_start = 0;
+ read_current_timer(&start);
+ start_jiffies = jiffies;
+ while (time_before_eq(jiffies, start_jiffies + 1)) {
+ pre_start = start;
+ read_current_timer(&start);
+ }
+ read_current_timer(&post_start);
+
+ pre_end = 0;
+ end = post_start;
+ while (time_before_eq(jiffies, start_jiffies + 1 +
+ DELAY_CALIBRATION_TICKS)) {
+ pre_end = end;
+ read_current_timer(&end);
+ }
+ read_current_timer(&post_end);
+
+ timer_rate_max = (post_end - pre_start) /
+ DELAY_CALIBRATION_TICKS;
+ timer_rate_min = (pre_end - post_start) /
+ DELAY_CALIBRATION_TICKS;
+
+ /*
+ * If the upper limit and lower limit of the timer_rate is
+ * >= 12.5% apart, redo calibration.
+ */
+ if (start >= post_end)
+ printk(KERN_NOTICE "calibrate_delay_direct() ignoring "
+ "timer_rate as we had a TSC wrap around"
+ " start=%lu >=post_end=%lu\n",
+ start, post_end);
+ if (start < post_end && pre_start != 0 && pre_end != 0 &&
+ (timer_rate_max - timer_rate_min) < (timer_rate_max >> 3)) {
+ good_timer_count++;
+ good_timer_sum += timer_rate_max;
+ measured_times[i] = timer_rate_max;
+ if (max < 0 || timer_rate_max > measured_times[max])
+ max = i;
+ if (min < 0 || timer_rate_max < measured_times[min])
+ min = i;
+ } else
+ measured_times[i] = 0;
+
+ }
+
+ /*
+ * Find the maximum & minimum - if they differ too much throw out the
+ * one with the largest difference from the mean and try again...
+ */
+ while (good_timer_count > 1) {
+ unsigned long estimate;
+ unsigned long maxdiff;
+
+ /* compute the estimate */
+ estimate = (good_timer_sum/good_timer_count);
+ maxdiff = estimate >> 3;
+
+ /* if range is within 12% let's take it */
+ if ((measured_times[max] - measured_times[min]) < maxdiff)
+ return estimate;
+
+ /* ok - drop the worse value and try again... */
+ good_timer_sum = 0;
+ good_timer_count = 0;
+ if ((measured_times[max] - estimate) <
+ (estimate - measured_times[min])) {
+ printk(KERN_NOTICE "calibrate_delay_direct() dropping "
+ "min bogoMips estimate %d = %lu\n",
+ min, measured_times[min]);
+ measured_times[min] = 0;
+ min = max;
+ } else {
+ printk(KERN_NOTICE "calibrate_delay_direct() dropping "
+ "max bogoMips estimate %d = %lu\n",
+ max, measured_times[max]);
+ measured_times[max] = 0;
+ max = min;
+ }
+
+ for (i = 0; i < MAX_DIRECT_CALIBRATION_RETRIES; i++) {
+ if (measured_times[i] == 0)
+ continue;
+ good_timer_count++;
+ good_timer_sum += measured_times[i];
+ if (measured_times[i] < measured_times[min])
+ min = i;
+ if (measured_times[i] > measured_times[max])
+ max = i;
+ }
+
+ }
+
+ printk(KERN_NOTICE "calibrate_delay_direct() failed to get a good "
+ "estimate for loops_per_jiffy.\nProbably due to long platform "
+ "interrupts. Consider using \"lpj=\" boot option.\n");
+ return 0;
+}
+#else
+static unsigned long __cpuinit calibrate_delay_direct(void) {return 0;}
+#endif
+
+/*
+ * This is the number of bits of precision for the loops_per_jiffy. Each
+ * time we refine our estimate after the first takes 1.5/HZ seconds, so try
+ * to start with a good estimate.
+ * For the boot cpu we can skip the delay calibration and assign it a value
+ * calculated based on the timer frequency.
+ * For the rest of the CPUs we cannot assume that the timer frequency is same as
+ * the cpu frequency, hence do the calibration for those.
+ */
+#define LPS_PREC 8
+
+static unsigned long __cpuinit calibrate_delay_converge(void)
+{
+ /* First stage - slowly accelerate to find initial bounds */
+ unsigned long lpj, lpj_base, ticks, loopadd, loopadd_base, chop_limit;
+ int trials = 0, band = 0, trial_in_band = 0;
+
+ lpj = (1<<12);
+
+ /* wait for "start of" clock tick */
+ ticks = jiffies;
+ while (ticks == jiffies)
+ ; /* nothing */
+ /* Go .. */
+ ticks = jiffies;
+ do {
+ if (++trial_in_band == (1<<band)) {
+ ++band;
+ trial_in_band = 0;
+ }
+ __delay(lpj * band);
+ trials += band;
+ } while (ticks == jiffies);
+ /*
+ * We overshot, so retreat to a clear underestimate. Then estimate
+ * the largest likely undershoot. This defines our chop bounds.
+ */
+ trials -= band;
+ loopadd_base = lpj * band;
+ lpj_base = lpj * trials;
+
+recalibrate:
+ lpj = lpj_base;
+ loopadd = loopadd_base;
+
+ /*
+ * Do a binary approximation to get lpj set to
+ * equal one clock (up to LPS_PREC bits)
+ */
+ chop_limit = lpj >> LPS_PREC;
+ while (loopadd > chop_limit) {
+ lpj += loopadd;
+ ticks = jiffies;
+ while (ticks == jiffies)
+ ; /* nothing */
+ ticks = jiffies;
+ __delay(lpj);
+ if (jiffies != ticks) /* longer than 1 tick */
+ lpj -= loopadd;
+ loopadd >>= 1;
+ }
+ /*
+ * If we incremented every single time possible, presume we've
+ * massively underestimated initially, and retry with a higher
+ * start, and larger range. (Only seen on x86_64, due to SMIs)
+ */
+ if (lpj + loopadd * 2 == lpj_base + loopadd_base * 2) {
+ lpj_base = lpj;
+ loopadd_base <<= 2;
+ goto recalibrate;
+ }
+
+ return lpj;
+}
+
+static DEFINE_PER_CPU(unsigned long, cpu_loops_per_jiffy) = { 0 };
+
+/*
+ * Check if cpu calibration delay is already known. For example,
+ * some processors with multi-core sockets may have all cores
+ * with the same calibration delay.
+ *
+ * Architectures should override this function if a faster calibration
+ * method is available.
+ */
+unsigned long __attribute__((weak)) __cpuinit calibrate_delay_is_known(void)
+{
+ return 0;
+}
+
+void __cpuinit calibrate_delay(void)
+{
+ unsigned long lpj;
+ static bool printed;
+ int this_cpu = smp_processor_id();
+
+ if (per_cpu(cpu_loops_per_jiffy, this_cpu)) {
+ lpj = per_cpu(cpu_loops_per_jiffy, this_cpu);
+ if (!printed)
+ pr_info("Calibrating delay loop (skipped) "
+ "already calibrated this CPU");
+ } else if (preset_lpj) {
+ lpj = preset_lpj;
+ if (!printed)
+ pr_info("Calibrating delay loop (skipped) "
+ "preset value.. ");
+ } else if ((!printed) && lpj_fine) {
+ lpj = lpj_fine;
+ pr_info("Calibrating delay loop (skipped), "
+ "value calculated using timer frequency.. ");
+ } else if ((lpj = calibrate_delay_is_known())) {
+ ;
+ } else if ((lpj = calibrate_delay_direct()) != 0) {
+ if (!printed)
+ pr_info("Calibrating delay using timer "
+ "specific routine.. ");
+ } else {
+ if (!printed)
+ pr_info("Calibrating delay loop... ");
+ lpj = calibrate_delay_converge();
+ }
+ per_cpu(cpu_loops_per_jiffy, this_cpu) = lpj;
+ if (!printed)
+ pr_cont("%lu.%02lu BogoMIPS (lpj=%lu)\n",
+ lpj/(500000/HZ),
+ (lpj/(5000/HZ)) % 100, lpj);
+
+ loops_per_jiffy = lpj;
+ printed = true;
+}