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view src/cs/riviera/rvt/rvt_keepalive.c @ 220:0ed36de51973

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ABB semaphore protection overhaul The ABB semaphone protection logic that came with TCS211 from TI was broken in several ways: * Some semaphore-protected functions were called from Application_Initialize() context. NU_Obtain_Semaphore() called with NU_SUSPEND fails with NU_INVALID_SUSPEND in this context, but the return value wasn't checked, and NU_Release_Semaphore() would be called unconditionally at the end. The latter call would increment the semaphore count past 1, making the semaphore no longer binary and thus no longer effective for resource protection. The fix is to check the return value from NU_Obtain_Semaphore() and skip the NU_Release_Semaphore() call if the semaphore wasn't properly obtained. * Some SPI hardware manipulation was being done before entering the semaphore- protected critical section. The fix is to reorder the code: first obtain the semaphore, then do everything else. * In the corner case of L1/DSP recovery, l1_abb_power_on() would call some non-semaphore-protected ABB & SPI init functions. The fix is to skip those calls in the case of recovery. * A few additional corner cases existed, all of which are fixed by making ABB semaphore protection 100% consistent for all ABB functions and code paths. There is still one remaining problem of priority inversion: suppose a low- priority task calls an ABB function, and some medium-priority task just happens to preempt right in the middle of that semaphore-protected ABB operation. Then the high-priority SPI task is locked out for a non-deterministic time until that medium-priority task finishes its work and goes back to sleep. This priority inversion problem remains outstanding for now.
author Mychaela Falconia <falcon@freecalypso.org>
date Mon, 26 Apr 2021 20:55:25 +0000
parents 4e78acac3d88
children
line wrap: on
line source

/*
 * This module is a FreeCalypso addition.  Here we implement the special
 * operation mode that is only used when a device that was originally
 * meant to be a phone handset is turned into a pseudo-modem with no UI,
 * requiring connection to a host computer running rvinterf for control.
 */

#ifdef PSEUDO_MODEM_KEEPALIVE

#include "nucleus.h"

#include "abb.h"

#include "rv/general.h"
#include "rv/rv_general.h"
#include "rvf/rvf_api.h"
#include "rvt/rvt_gen.h"
#include "rvt/rvt_def_i.h"
#include "rvt/rvt_env.h"
#include "rvt/rvt_env_i.h"
#include "rvm/rvm_use_id_list.h"

#include "uart/serialswitch.h"

#include <string.h>

volatile UINT8 rvt_keepalive_counter;

void rvt_keepalive_input(T_RVT_BUFFER p_msg, UINT16 msg_length)
{
	/* Checking for an invalid PDU. */
	if ((p_msg == NULL) || (msg_length != 1))
		return;

	/* Check for the correct opcode */
	if (*p_msg != 'A')
		return;

	/* good keepalive response from external host */
	rvt_keepalive_counter = 0;
}

void rvt_keepalive_register(void)
{
	T_RVT_USER_ID rvt_id;

	rvt_register_id("KEEPALIVE", &rvt_id, rvt_keepalive_input);
}

static void keepalive_send(UINT8 *buf, UINT32 size)
{
	UINT32 sent;

	for (sent = 0; sent < size; )
		sent += SER_tr_WriteNBytes(SER_LAYER_1, buf + sent,
					   size - sent);
}

#ifdef PSEUDO_MODEM_USB
static char poweroff_msg[] = "System: USB unplugged, powering off";
#else
static char poweroff_msg[] = "System: no keepalive response, powering off";
static UINT8 keepalive_msg[2] = {RVT_KEEPALIVE_HEADER, 'Q'};
#endif

static void keepalive_poweroff(void)
{
	UINT8 poweroff_msg_buf[50], *p;

	p = poweroff_msg_buf;
	*p++ = RVT_RV_HEADER;
	*p++ = 0;
	*p++ = 0;
	*p++ = 0;
	*p++ = 0;
	*p++ = RV_TRACE_LEVEL_ERROR;
	strcpy((char *)p, poweroff_msg);
	keepalive_send(poweroff_msg_buf, strlen(poweroff_msg) + 6);
	/* do it */
	ABB_Power_Off();
}

void rvt_keepalive_process(void)
{
	SYS_UWORD16 abb_status;

	abb_status = ABB_Read_Status();
	if (abb_status & CHGPRES) {
		rvt_keepalive_counter = 0;
		return;
	}

#ifdef PSEUDO_MODEM_USB
	keepalive_poweroff();
#else
	if (rvt_keepalive_counter >= 3)
		keepalive_poweroff();
	else {
		rvt_keepalive_counter++;
		keepalive_send(keepalive_msg, sizeof keepalive_msg);
	}
#endif
}

#endif