-
Lorenz Meier authored
This reduces interrupt load significantly.
Lorenz Meier authoredThis reduces interrupt load significantly.
drv_hrt.c 22.41 KiB
/****************************************************************************
*
* Copyright (c) 2016-2017 PX4 Development Team. All rights reserved.
*
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* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
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* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name PX4 nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
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/**
* @file drv_hrt.c
* Author: David Sidrane <david_s5@nscdg.com>
*
* High-resolution timer callouts and timekeeping.
*
* This can use any Kinetis TPM timer.
*
* Note that really, this could use systick too, but that's
* monopolised by NuttX and stealing it would just be awkward.
*
* We don't use the NuttX Kinetis driver per se; rather, we
* claim the timer and then drive it directly.
*/
#include <px4_config.h>
#include <systemlib/px4_macros.h>
#include <lib/perf/perf_counter.h>
#include <nuttx/arch.h>
#include <nuttx/irq.h>
#include <sys/types.h>
#include <stdbool.h>
#include <assert.h>
#include <debug.h>
#include <time.h>
#include <queue.h>
#include <errno.h>
#include <string.h>
#include <board_config.h>
#include <drivers/drv_hrt.h>
#include "kinetis.h"
#include "chip/kinetis_sim.h"#include "kinetis_tpm.h"
#undef PPM_DEBUG
#ifdef CONFIG_DEBUG_HRT
# define hrtinfo _info
#else
# define hrtinfo(x...)
#endif
#define CAT3_(A, B, C) A##B##C
#define CAT3(A, B, C) CAT3_(A, B, C)
#ifdef HRT_TIMER
#define HRT_TIMER_FREQ 1000000
/* HRT configuration */
#define HRT_TIMER_CLOCK BOARD_TPM_FREQ /* The input clock frequency to the TPM block */
#define HRT_TIMER_BASE CAT(CAT(KINETIS_TPM, HRT_TIMER),_BASE) /* The Base address of the TPM */
#define HRT_TIMER_VECTOR CAT(KINETIS_IRQ_TPM, HRT_TIMER) /* The TPM Interrupt vector */
#define HRT_SIM_SCGC2_TPM CAT(SIM_SCGC2_TPM, HRT_TIMER) /* The Clock Gating enable bit for this TPM */
#if HRT_TIMER == 1 && defined(CONFIG_KINETIS_TPM1)
# error must not set CONFIG_KINETIS_TPM1=y and HRT_TIMER=1
#elif HRT_TIMER == 2 && defined(CONFIG_KINETIS_TPM2)
# error must not set CONFIG_STM32_TIM2=y and HRT_TIMER=2
#endif
/*
* HRT clock must be a multiple of 1MHz greater than 1MHz
*/
#if (HRT_TIMER_CLOCK % HRT_TIMER_FREQ) != 0
# error HRT_TIMER_CLOCK must be a multiple of 1MHz
#endif
#if HRT_TIMER_CLOCK <= HRT_TIMER_FREQ
# error HRT_TIMER_CLOCK must be greater than 1MHz
#endif
/**
* Minimum/maximum deadlines.
*
* These are suitable for use with a 16-bit timer/counter clocked
* at 1MHz. The high-resolution timer need only guarantee that it
* not wrap more than once in the 50ms period for absolute time to
* be consistently maintained.
*
* The minimum deadline must be such that the time taken between
* reading a time and writing a deadline to the timer cannot
* result in missing the deadline.
*/
#define HRT_INTERVAL_MIN 50
#define HRT_INTERVAL_MAX 50000
/*
* Period of the free-running counter, in microseconds.
*/
#define HRT_COUNTER_PERIOD 65536
/*
* Scaling factor(s) for the free-running counter; convert an input
* in counts to a time in microseconds.
*/
#define HRT_COUNTER_SCALE(_c) (_c)
/* Register accessors */
#define _REG(_addr) (*(volatile uint32_t *)(_addr))
/* Timer register accessors */
#define REG(_reg) _REG(HRT_TIMER_BASE + (_reg))
#define rSC REG(KINETIS_TPM_SC_OFFSET)
#define rCNT REG(KINETIS_TPM_CNT_OFFSET)
#define rMOD REG(KINETIS_TPM_MOD_OFFSET)
#define rC0SC REG(KINETIS_TPM_C0SC_OFFSET)
#define rC0V REG(KINETIS_TPM_C0V_OFFSET)
#define rC1SC REG(KINETIS_TPM_C1SC_OFFSET)
#define rC1V REG(KINETIS_TPM_C1V_OFFSET)
#define rSTATUS REG(KINETIS_TPM_STATUS_OFFSET)
#define rCOMBINE REG(KINETIS_TPM_COMBINE_OFFSET)
#define rPOL REG(KINETIS_TPM_POL_OFFSET)
#define rFILTER REG(KINETIS_TPM_FILTER_OFFSET)
#define rQDCTRL REG(KINETIS_TPM_QDCTRL_OFFSET)
#define rCONF REG(KINETIS_TPM_CONF_OFFSET)
/*
* Specific registers and bits used by HRT sub-functions
*/
# define rCNV_HRT CAT3(rC, HRT_TIMER_CHANNEL, V) /* Channel Value Register used by HRT */
# define rCNSC_HRT CAT3(rC, HRT_TIMER_CHANNEL, SC) /* Channel Status and Control Register used by HRT */
# define STATUS_HRT CAT3(TPM_STATUS_CH, HRT_TIMER_CHANNEL, F) /* Capture and Compare Status Register used by HRT */
#if (HRT_TIMER_CHANNEL != 0) && (HRT_TIMER_CHANNEL != 1)
# error HRT_TIMER_CHANNEL must be a value between 0 and 1
#endif
/*
* Queue of callout entries.
*/
static struct sq_queue_s callout_queue;
/* latency baseline (last compare value applied) */
static uint16_t latency_baseline;
/* timer count at interrupt (for latency purposes) */
static uint16_t latency_actual;
/* timer-specific functions */
static void hrt_tim_init(void);
static int hrt_tim_isr(int irq, void *context, void *args);
static void hrt_latency_update(void);
/* callout list manipulation */
static void hrt_call_internal(struct hrt_call *entry, hrt_abstime deadline, hrt_abstime interval, hrt_callout callout,
void *arg);
static void hrt_call_enter(struct hrt_call *entry);
static void hrt_call_reschedule(void);
static void hrt_call_invoke(void);
#if !defined(HRT_PPM_CHANNEL)
/* When HRT_PPM_CHANNEL provide null operations */
# define STATUS_PPM 0
# define POL_PPM 0
# define CNSC_PPM 0
#else
/* Specific registers and bits used by PPM sub-functions */
#define rCNV_PPM CAT3(rC,HRT_PPM_CHANNEL,V) /* Channel Value Register used by PPM */
#define rCNSC_PPM CAT3(rC,HRT_PPM_CHANNEL,SC) /* Channel Status and Control Register used by PPM */
#define STATUS_PPM CAT3(TPM_STATUS_CH, HRT_PPM_CHANNEL ,F) /* Capture and Compare Status Register used by PPM */
#define CNSC_PPM (TPM_CnSC_CHIE | TPM_CnSC_ELSB | TPM_CnSC_ELSA) /* Input Capture configuration both Edges, interrupt */
/* Sanity checking */
#if (HRT_PPM_CHANNEL != 0) && (HRT_PPM_CHANNEL != 1)
# error HRT_PPM_CHANNEL must be a value between 0 and 1
#endif
# if (HRT_PPM_CHANNEL == HRT_TIMER_CHANNEL)
# error HRT_PPM_CHANNEL must not be the same as HRT_TIMER_CHANNEL
# endif
/*
* PPM decoder tuning parameters
*/
# define PPM_MIN_PULSE_WIDTH 200 /**< minimum width of a valid first pulse */
# define PPM_MAX_PULSE_WIDTH 600 /**< maximum width of a valid first pulse */
# define PPM_MIN_CHANNEL_VALUE 800 /**< shortest valid channel signal */
# define PPM_MAX_CHANNEL_VALUE 2200 /**< longest valid channel signal */
# define PPM_MIN_START 2300 /**< shortest valid start gap (only 2nd part of pulse) */
/* decoded PPM buffer */
# define PPM_MIN_CHANNELS 5
# define PPM_MAX_CHANNELS 20
/** Number of same-sized frames required to 'lock' */
# define PPM_CHANNEL_LOCK 4 /**< should be less than the input timeout */
__EXPORT uint16_t ppm_buffer[PPM_MAX_CHANNELS];
__EXPORT uint16_t ppm_frame_length = 0;
__EXPORT unsigned ppm_decoded_channels = 0;
__EXPORT uint64_t ppm_last_valid_decode = 0;
# if defined(PPM_DEBUG)
#define EDGE_BUFFER_COUNT 32
/* PPM edge history */
__EXPORT uint16_t ppm_edge_history[EDGE_BUFFER_COUNT];
unsigned ppm_edge_next;
/* PPM pulse history */
__EXPORT uint16_t ppm_pulse_history[EDGE_BUFFER_COUNT];
unsigned ppm_pulse_next;
# endif
static uint16_t ppm_temp_buffer[PPM_MAX_CHANNELS];
/** PPM decoder state machine */
struct {
uint16_t last_edge; /**< last capture time */
uint16_t last_mark; /**< last significant edge */
uint16_t frame_start; /**< the frame width */
unsigned next_channel; /**< next channel index */
enum {
UNSYNCH = 0,
ARM,
ACTIVE,
INACTIVE
} phase;
} ppm;
static void hrt_ppm_decode(uint32_t status);
#endif /* HRT_PPM_CHANNEL */
/**
* Initialize the timer we are going to use.
*/static void hrt_tim_init(void)
{
/* Select a the clock source to the TPM */
uint32_t regval = _REG(KINETIS_SIM_SOPT2);
regval &= ~(SIM_SOPT2_TPMSRC_MASK);
regval |= BOARD_TPM_CLKSRC;
_REG(KINETIS_SIM_SOPT2) = regval;
/* Enabled System Clock Gating Control for TPM */
regval = _REG(KINETIS_SIM_SCGC2);
regval |= HRT_SIM_SCGC2_TPM;
_REG(KINETIS_SIM_SCGC2) = regval;
/* claim our interrupt vector */
irq_attach(HRT_TIMER_VECTOR, hrt_tim_isr, NULL);
/* disable and configure the timer */
rSC = TPM_SC_TOF;
rCNT = 0;
rMOD = HRT_COUNTER_PERIOD - 1;
rSTATUS = (TPM_STATUS_TOF | STATUS_HRT | STATUS_PPM);
rCNSC_HRT = (TPM_CnSC_CHF | TPM_CnSC_CHIE | TPM_CnSC_MSA);
rCNSC_PPM = (TPM_CnSC_CHF | CNSC_PPM);
rCOMBINE = 0;
rPOL = 0;
rFILTER = 0;
rQDCTRL = 0;
rCONF = TPM_CONF_DBGMODE_CONT;
/* set an initial capture a little ways off */
rCNV_PPM = 0;
rCNV_HRT = 1000;
/* enable the timer */
rSC |= (TPM_SC_TOIE | TPM_SC_CMOD_LPTPM_CLK | TPM_SC_PS_DIV16);
/* enable interrupts */
up_enable_irq(HRT_TIMER_VECTOR);
}
#ifdef HRT_PPM_CHANNEL
/**
* Handle the PPM decoder state machine.
*/
static void hrt_ppm_decode(uint32_t status)
{
uint16_t count = rCNV_PPM;
uint16_t width;
uint16_t interval;
unsigned i;
/* how long since the last edge? - this handles counter wrapping implicitly. */
width = count - ppm.last_edge;
#if PPM_DEBUG
ppm_edge_history[ppm_edge_next++] = width;
if (ppm_edge_next >= EDGE_BUFFER_COUNT) {
ppm_edge_next = 0; }
#endif
/*
* if this looks like a start pulse, then push the last set of values
* and reset the state machine
*/
if (width >= PPM_MIN_START) {
/*
* If the number of channels changes unexpectedly, we don't want
* to just immediately jump on the new count as it may be a result
* of noise or dropped edges. Instead, take a few frames to settle.
*/
if (ppm.next_channel != ppm_decoded_channels) {
static unsigned new_channel_count;
static unsigned new_channel_holdoff;
if (new_channel_count != ppm.next_channel) {
/* start the lock counter for the new channel count */
new_channel_count = ppm.next_channel;
new_channel_holdoff = PPM_CHANNEL_LOCK;
} else if (new_channel_holdoff > 0) {
/* this frame matched the last one, decrement the lock counter */
new_channel_holdoff--;
} else {
/* we have seen PPM_CHANNEL_LOCK frames with the new count, accept it */
ppm_decoded_channels = new_channel_count;
new_channel_count = 0;
}
} else {
/* frame channel count matches expected, let's use it */
if (ppm.next_channel >= PPM_MIN_CHANNELS) {
for (i = 0; i < ppm.next_channel; i++) {
ppm_buffer[i] = ppm_temp_buffer[i];
}
ppm_last_valid_decode = hrt_absolute_time();
}
}
/* reset for the next frame */
ppm.next_channel = 0;
/* next edge is the reference for the first channel */
ppm.phase = ARM;
ppm.last_edge = count;
return;
}
switch (ppm.phase) {
case UNSYNCH:
/* we are waiting for a start pulse - nothing useful to do here */
break;
case ARM:
/* we expect a pulse giving us the first mark */
if (width < PPM_MIN_PULSE_WIDTH || width > PPM_MAX_PULSE_WIDTH) {
goto error; /* pulse was too short or too long */
}
/* record the mark timing, expect an inactive edge */
ppm.last_mark = ppm.last_edge;
/* frame length is everything including the start gap */
ppm_frame_length = (uint16_t)(ppm.last_edge - ppm.frame_start);
ppm.frame_start = ppm.last_edge;
ppm.phase = ACTIVE;
break;
case INACTIVE:
/* we expect a short pulse */
if (width < PPM_MIN_PULSE_WIDTH || width > PPM_MAX_PULSE_WIDTH) {
goto error; /* pulse was too short or too long */
}
/* this edge is not interesting, but now we are ready for the next mark */
ppm.phase = ACTIVE;
break;
case ACTIVE:
/* determine the interval from the last mark */
interval = count - ppm.last_mark;
ppm.last_mark = count;
#if PPM_DEBUG
ppm_pulse_history[ppm_pulse_next++] = interval;
if (ppm_pulse_next >= EDGE_BUFFER_COUNT) {
ppm_pulse_next = 0;
}
#endif
/* if the mark-mark timing is out of bounds, abandon the frame */
if ((interval < PPM_MIN_CHANNEL_VALUE) || (interval > PPM_MAX_CHANNEL_VALUE)) {
goto error;
}
/* if we have room to store the value, do so */
if (ppm.next_channel < PPM_MAX_CHANNELS) {
ppm_temp_buffer[ppm.next_channel++] = interval;
}
ppm.phase = INACTIVE;
break;
}
ppm.last_edge = count;
return;
/* the state machine is corrupted; reset it */
error:
/* we don't like the state of the decoder, reset it and try again */
ppm.phase = UNSYNCH;
ppm_decoded_channels = 0;
}
#endif /* HRT_PPM_CHANNEL */
/**
* Handle the compare interrupt by calling the callout dispatcher
* and then re-scheduling the next deadline.
*/
static int
hrt_tim_isr(int irq, void *context, void *arg)
{
/* grab the timer for latency tracking purposes */
latency_actual = rCNT;
/* copy interrupt status */
uint32_t status = rSTATUS;
/* ack the interrupts we just read */
rSTATUS = status;
#ifdef HRT_PPM_CHANNEL
/* was this a PPM edge? */
if (status & (STATUS_PPM)) {
hrt_ppm_decode(status);
}
#endif
/* was this a timer tick? */
if (status & STATUS_HRT) {
/* do latency calculations */
hrt_latency_update();
/* run any callouts that have met their deadline */
hrt_call_invoke();
/* and schedule the next interrupt */
hrt_call_reschedule();
}
return OK;
}
/**
* Fetch a never-wrapping absolute time value in microseconds from
* some arbitrary epoch shortly after system start.
*/
hrt_abstime
hrt_absolute_time(void)
{
hrt_abstime abstime;
uint32_t count;
irqstate_t flags;
/*
* Counter state. Marked volatile as they may change
* inside this routine but outside the irqsave/restore
* pair. Discourage the compiler from moving loads/stores
* to these outside of the protected range.
*/
static volatile hrt_abstime base_time;
static volatile uint32_t last_count;
/* prevent re-entry */
flags = px4_enter_critical_section();
/* get the current counter value */
count = rCNT;
/*
* Determine whether the counter has wrapped since the
* last time we're called.
*
* This simple test is sufficient due to the guarantee that
* we are always called at least once per counter period.
*/
if (count < last_count) {
base_time += HRT_COUNTER_PERIOD;
}
/* save the count for next time */
last_count = count;
/* compute the current time */
abstime = HRT_COUNTER_SCALE(base_time + count);
px4_leave_critical_section(flags);
return abstime;
}
/**
* Convert a timespec to absolute time
*/
hrt_abstime
ts_to_abstime(const struct timespec *ts)
{
hrt_abstime result;
result = (hrt_abstime)(ts->tv_sec) * 1000000;
result += ts->tv_nsec / 1000;
return result;
}
/**
* Convert absolute time to a timespec.
*/
void
abstime_to_ts(struct timespec *ts, hrt_abstime abstime)
{
ts->tv_sec = abstime / 1000000;
abstime -= ts->tv_sec * 1000000;
ts->tv_nsec = abstime * 1000;
}
/**
* Compare a time value with the current time.
*/
hrt_abstime
hrt_elapsed_time(const volatile hrt_abstime *then)
{
hrt_abstime delta = hrt_absolute_time() - *then;
return delta;
}
/**
* Compare a time value with the current time as atomic operation.
*/
hrt_abstime
hrt_elapsed_time_atomic(const volatile hrt_abstime *then)
{
irqstate_t flags = px4_enter_critical_section();
hrt_abstime delta = hrt_absolute_time() - *then;
px4_leave_critical_section(flags);
return delta;
}
/**
* Store the absolute time in an interrupt-safe fashion
*/
hrt_abstime
hrt_store_absolute_time(volatile hrt_abstime *now)
{
irqstate_t flags = px4_enter_critical_section();
hrt_abstime ts = hrt_absolute_time();
px4_leave_critical_section(flags);
return ts;
}
/**
* Initialize the high-resolution timing module.
*/
void
hrt_init(void)
{
sq_init(&callout_queue);
hrt_tim_init();
#ifdef HRT_PPM_CHANNEL
/* configure the PPM input pin */
px4_arch_configgpio(GPIO_PPM_IN);
#endif
}
/**
* Call callout(arg) after interval has elapsed.
*/
void
hrt_call_after(struct hrt_call *entry, hrt_abstime delay, hrt_callout callout, void *arg)
{
hrt_call_internal(entry,
hrt_absolute_time() + delay,
0,
callout,
arg);
}
/**
* Call callout(arg) at calltime.
*/
void
hrt_call_at(struct hrt_call *entry, hrt_abstime calltime, hrt_callout callout, void *arg)
{
hrt_call_internal(entry, calltime, 0, callout, arg);
}
/**
* Call callout(arg) every period.
*/
void
hrt_call_every(struct hrt_call *entry, hrt_abstime delay, hrt_abstime interval, hrt_callout callout, void *arg)
{
hrt_call_internal(entry,
hrt_absolute_time() + delay,
interval,
callout,
arg);
}
static void
hrt_call_internal(struct hrt_call *entry, hrt_abstime deadline, hrt_abstime interval, hrt_callout callout, void *arg)
{
irqstate_t flags = px4_enter_critical_section();
/* if the entry is currently queued, remove it */
/* note that we are using a potentially uninitialized
entry->link here, but it is safe as sq_rem() doesn't
dereference the passed node unless it is found in the
list. So we potentially waste a bit of time searching the
queue for the uninitialized entry->link but we don't do
anything actually unsafe.
*/ if (entry->deadline != 0) {
sq_rem(&entry->link, &callout_queue);
}
entry->deadline = deadline;
entry->period = interval;
entry->callout = callout;
entry->arg = arg;
hrt_call_enter(entry);
px4_leave_critical_section(flags);
}
/**
* If this returns true, the call has been invoked and removed from the callout list.
*
* Always returns false for repeating callouts.
*/
bool
hrt_called(struct hrt_call *entry)
{
return (entry->deadline == 0);
}
/**
* Remove the entry from the callout list.
*/
void
hrt_cancel(struct hrt_call *entry)
{
irqstate_t flags = px4_enter_critical_section();
sq_rem(&entry->link, &callout_queue);
entry->deadline = 0;
/* if this is a periodic call being removed by the callout, prevent it from
* being re-entered when the callout returns.
*/
entry->period = 0;
px4_leave_critical_section(flags);
}
static void
hrt_call_enter(struct hrt_call *entry)
{
struct hrt_call *call, *next;
call = (struct hrt_call *)sq_peek(&callout_queue);
if ((call == NULL) || (entry->deadline < call->deadline)) {
sq_addfirst(&entry->link, &callout_queue);
hrtinfo("call enter at head, reschedule\n");
/* we changed the next deadline, reschedule the timer event */
hrt_call_reschedule();
} else {
do {
next = (struct hrt_call *)sq_next(&call->link);
if ((next == NULL) || (entry->deadline < next->deadline)) {
hrtinfo("call enter after head\n");
sq_addafter(&call->link, &entry->link, &callout_queue);
break;
}
} while ((call = next) != NULL);
}
hrtinfo("scheduled\n");}
static void
hrt_call_invoke(void)
{
struct hrt_call *call;
hrt_abstime deadline;
while (true) {
/* get the current time */
hrt_abstime now = hrt_absolute_time();
call = (struct hrt_call *)sq_peek(&callout_queue);
if (call == NULL) {
break;
}
if (call->deadline > now) {
break;
}
sq_rem(&call->link, &callout_queue);
hrtinfo("call pop\n");
/* save the intended deadline for periodic calls */
deadline = call->deadline;
/* zero the deadline, as the call has occurred */
call->deadline = 0;
/* invoke the callout (if there is one) */
if (call->callout) {
hrtinfo("call %p: %p(%p)\n", call, call->callout, call->arg);
call->callout(call->arg);
}
/* if the callout has a non-zero period, it has to be re-entered */
if (call->period != 0) {
// re-check call->deadline to allow for
// callouts to re-schedule themselves
// using hrt_call_delay()
if (call->deadline <= now) {
call->deadline = deadline + call->period;
}
hrt_call_enter(call);
}
}
}
/**
* Reschedule the next timer interrupt.
*
* This routine must be called with interrupts disabled.
*/
static void
hrt_call_reschedule()
{
hrt_abstime now = hrt_absolute_time();
struct hrt_call *next = (struct hrt_call *)sq_peek(&callout_queue);
hrt_abstime deadline = now + HRT_INTERVAL_MAX;
/*
* Determine what the next deadline will be.
*
* Note that we ensure that this will be within the counter
* period, so that when we truncate all but the low 16 bits
* the next time the compare matches it will be the deadline
* we want. *
* It is important for accurate timekeeping that the compare
* interrupt fires sufficiently often that the base_time update in
* hrt_absolute_time runs at least once per timer period.
*/
if (next != NULL) {
hrtinfo("entry in queue\n");
if (next->deadline <= (now + HRT_INTERVAL_MIN)) {
hrtinfo("pre-expired\n");
/* set a minimal deadline so that we call ASAP */
deadline = now + HRT_INTERVAL_MIN;
} else if (next->deadline < deadline) {
hrtinfo("due soon\n");
deadline = next->deadline;
}
}
hrtinfo("schedule for %u at %u\n", (unsigned)(deadline & 0xffffffff), (unsigned)(now & 0xffffffff));
/* set the new compare value and remember it for latency tracking */
rCNV_HRT = latency_baseline = deadline & 0xffff;
}
static void
hrt_latency_update(void)
{
uint16_t latency = latency_actual - latency_baseline;
unsigned index;
/* bounded buckets */
for (index = 0; index < LATENCY_BUCKET_COUNT; index++) {
if (latency <= latency_buckets[index]) {
latency_counters[index]++;
return;
}
}
/* catch-all at the end */
latency_counters[index]++;
}
void
hrt_call_init(struct hrt_call *entry)
{
memset(entry, 0, sizeof(*entry));
}
void
hrt_call_delay(struct hrt_call *entry, hrt_abstime delay)
{
entry->deadline = hrt_absolute_time() + delay;
}
#endif /* HRT_TIMER */