Mike R
USB device stack, with KL25Z fixes for USB 3.0 hosts and sleep/resume interrupt handling
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USBDevice
by 
mbed official
This is an overhauled version of the standard mbed USB device-side driver library, with bug fixes for KL25Z devices. It greatly improves reliability and stability of USB on the KL25Z, especially with devices using multiple endpoints concurrently.
I've had some nagging problems with the base mbed implementation for a long time, manifesting as occasional random disconnects that required rebooting the device. Recently (late 2015), I started implementing a USB device on the KL25Z that used multiple endpoints, and suddenly the nagging, occasional problems turned into frequent and predictable crashes. This forced me to delve into the USB stack and figure out what was really going on. Happily, the frequent crashes made it possible to track down and fix the problems. This new version is working very reliably in my testing - the random disconnects seem completely eradicated, even under very stressful conditions for the device.
Summary
- Overall stability improvements
- USB 3.0 host support
- Stalled endpoint fixes
- Sleep/resume notifications
- Smaller memory footprint
- General code cleanup
Update - 2/15/2016
My recent fixes introduced a new problem that made the initial connection fail most of the time on certain hosts. It's not clear if the common thread was a particular type of motherboard or USB chip set, or a specific version of Windows, or what, but several people ran into it. We tracked the problem down to the "stall" fixes in the earlier updates, which we now know weren't quite the right fixes after all. The latest update (2/15/2016) fixes this. It has new and improved "unstall" handling that so far works well with diverse hosts.
Race conditions and overall stability
The base mbed KL25Z implementation has a lot of problems with "race conditions" - timing problems that can happen when hardware interrupts occur at inopportune moments. The library shares a bunch of static variable data between interrupt handler context and regular application context. This isn't automatically a bad thing, but it does require careful coordination to make sure that the interrupt handler doesn't corrupt data that the other code was in the middle of updating when an interrupt occurs. The base mbed code, though, doesn't do any of the necessary coordination. This makes it kind of amazing that the base code worked at all for anyone, but I guess the interrupt rate is low enough in most applications that the glitch rate was below anyone's threshold to seriously investigate.
This overhaul adds the necessary coordination for the interrupt handlers to protect against these data corruptions. I think it's very solid now, and hopefully entirely free of the numerous race conditions in the old code. It's always hard to be certain that you've fixed every possible bug like this because they strike (effectively) at random, but I'm pretty confident: my test application was reliably able to trigger glitches in the base code in a matter of minutes, but the same application (with the overhauled library) now runs for days on end without dropping the connection.
Stalled endpoint fixes
USB has a standard way of handling communications errors called a "stall", which basically puts the connection into an error mode to let both sides know that they need to reset their internal states and sync up again. The original mbed version of the USB device library doesn't seem to have the necessary code to recover from this condition properly. The KL25Z hardware does some of the work, but it also seems to require the software to take some steps to "un-stall" the connection. (I keep saying "seems to" because the hardware reference material is very sketchy about all of this. Most of what I've figured out is from observing the device in action with a Windows host.) This new version adds code to do the necessary re-syncing and get the connection going again, automatically, and transparently to the user.
USB 3.0 Hosts
The original mbed code sometimes didn't work when connecting to hosts with USB 3.0 ports. This didn't affect every host, but it affected many of them. The common element seemed to be the Intel Haswell chip set on the host, but there may be other chip sets affected as well. In any case, the problem affected many PCs from the Windows 7 and 8 generation, as well as many Macs. It was possible to work around the problem by avoiding USB 3.0 ports - you could use a USB 2 port on the host, or plug a USB 2 hub between the host and device. But I wanted to just fix the problem and eliminate the need for such workarounds. This modified version of the library has such a fix, which so far has worked for everyone who's tried.
Sleep/resume notifications
This modified version also contains an innocuous change to the KL25Z USB HAL code to handle sleep and resume interrupts with calls to suspendStateChanged(). The original KL25Z code omitted these calls (and in fact didn't even enable the interrupts), but I think this was an unintentional oversight - the notifier function is part of the generic API, and other supported boards all implement it. I use this feature in my own application so that I can distinguish sleep mode from actual disconnects and handle the two conditions correctly.
Smaller memory footprint
The base mbed version of the code allocates twice as much memory for USB buffers as it really needed to. It looks like the original developers intended to implement the KL25Z USB hardware's built-in double-buffering mechanism, but they ultimately abandoned that effort. But they left in the double memory allocation. This version removes that and allocates only what's actually needed. The USB buffers aren't that big (128 bytes per endpoint), so this doesn't save a ton of memory, but even a little memory is pretty precious on this machine given that it only has 16K.
(I did look into adding the double-buffering support that the original developers abandoned, but after some experimentation I decided they were right to skip it. It just doesn't seem to mesh well with the design of the rest of the mbed USB code. I think it would take a major rewrite to make it work, and it doesn't seem worth the effort given that most applications don't need it - it would only benefit applications that are moving so much data through USB that they're pushing the limits of the CPU. And even for those, I think it would be a lot simpler to build a purely software-based buffer rotation mechanism.)
General code cleanup
The KL25Z HAL code in this version has greatly expanded commentary and a lot of general cleanup. Some of the hardware constants were given the wrong symbolic names (e.g., EVEN and ODD were reversed), and many were just missing (written as hard-coded numbers without explanation). I fixed the misnomers and added symbolic names for formerly anonymous numbers. Hopefully the next person who has to overhaul this code will at least have an easier time understanding what I thought I was doing!
USBDevice/USBHAL_KL25Z.cpp
- Committer:
- samux
- Date:
- 2013-03-01
- Revision:
- 8:335f2506f422
- Child:
- 9:354942d2fa38
File content as of revision 8:335f2506f422:
/* Copyright (c) 2010-2011 mbed.org, MIT License
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of this software
* and associated documentation files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all copies or
* substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
* BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#if defined(TARGET_KL25Z)
#include "USBHAL.h"
USBHAL * USBHAL::instance;
static volatile int epComplete = 0;
// Convert physical endpoint number to register bit
#define EP(endpoint) (1<<(endpoint))
// Convert physical to logical
#define PHY_TO_LOG(endpoint) ((endpoint)>>1)
// Get endpoint direction
#define IN_EP(endpoint) ((endpoint) & 1U ? true : false)
#define OUT_EP(endpoint) ((endpoint) & 1U ? false : true)
#define BD_OWN_MASK (1<<7)
#define BD_DATA01_MASK (1<<6)
#define BD_KEEP_MASK (1<<5)
#define BD_NINC_MASK (1<<4)
#define BD_DTS_MASK (1<<3)
#define BD_STALL_MASK (1<<2)
#define TX 1
#define RX 0
#define ODD 0
#define EVEN 1
// this macro waits a physical endpoint number
#define EP_BDT_IDX(ep, dir, odd) (((ep * 4) + (2 * dir) + (1 * odd)))
#define SETUP_TOKEN 0x0D
#define IN_TOKEN 0x09
#define OUT_TOKEN 0x01
#define TOK_PID(idx) ((bdt[idx].info >> 2) & 0x0F)
// for each endpt: 8 bytes
typedef struct BDT {
uint8_t info; // BD[0:7]
uint8_t dummy; // RSVD: BD[8:15]
uint16_t byte_count; // BD[16:32]
uint32_t address; // Addr
} BDT;
// there are:
// * 16 bidirectionnal endpt -> 32 physical endpt
// * as there are ODD and EVEN buffer -> 32*2 bdt
__attribute__((__aligned__(512))) BDT bdt[NUMBER_OF_PHYSICAL_ENDPOINTS * 2];
uint8_t endpoint_buffer[(NUMBER_OF_PHYSICAL_ENDPOINTS - 2) * 2][64];
uint8_t endpoint_buffer_iso[2*2][1023];
static uint8_t set_addr = 0;
static uint8_t addr = 0;
static uint32_t Data1 = 0x55555555;
static uint32_t frameNumber() {
return((USB0->FRMNUML | (USB0->FRMNUMH << 8) & 0x07FF));
}
uint32_t USBHAL::endpointReadcore(uint8_t endpoint, uint8_t *buffer) {
return 0;
}
USBHAL::USBHAL(void) {
// Disable IRQ
NVIC_DisableIRQ(USB0_IRQn);
// fill in callback array
epCallback[0] = &USBHAL::EP1_OUT_callback;
epCallback[1] = &USBHAL::EP1_IN_callback;
epCallback[2] = &USBHAL::EP2_OUT_callback;
epCallback[3] = &USBHAL::EP2_IN_callback;
epCallback[4] = &USBHAL::EP3_OUT_callback;
epCallback[5] = &USBHAL::EP3_IN_callback;
epCallback[6] = &USBHAL::EP4_OUT_callback;
epCallback[7] = &USBHAL::EP4_IN_callback;
epCallback[8] = &USBHAL::EP5_OUT_callback;
epCallback[9] = &USBHAL::EP5_IN_callback;
epCallback[10] = &USBHAL::EP6_OUT_callback;
epCallback[11] = &USBHAL::EP6_IN_callback;
epCallback[12] = &USBHAL::EP7_OUT_callback;
epCallback[13] = &USBHAL::EP7_IN_callback;
epCallback[14] = &USBHAL::EP8_OUT_callback;
epCallback[15] = &USBHAL::EP8_IN_callback;
epCallback[16] = &USBHAL::EP9_OUT_callback;
epCallback[17] = &USBHAL::EP9_IN_callback;
epCallback[18] = &USBHAL::EP10_OUT_callback;
epCallback[19] = &USBHAL::EP10_IN_callback;
epCallback[20] = &USBHAL::EP11_OUT_callback;
epCallback[21] = &USBHAL::EP11_IN_callback;
epCallback[22] = &USBHAL::EP12_OUT_callback;
epCallback[23] = &USBHAL::EP12_IN_callback;
epCallback[24] = &USBHAL::EP13_OUT_callback;
epCallback[25] = &USBHAL::EP13_IN_callback;
epCallback[26] = &USBHAL::EP14_OUT_callback;
epCallback[27] = &USBHAL::EP14_IN_callback;
epCallback[28] = &USBHAL::EP15_OUT_callback;
epCallback[29] = &USBHAL::EP15_IN_callback;
// choose usb src as PLL
SIM->SOPT2 |= (SIM_SOPT2_USBSRC_MASK | SIM_SOPT2_PLLFLLSEL_MASK);
// enable OTG clock
SIM->SCGC4 |= SIM_SCGC4_USBOTG_MASK;
// Attach IRQ
instance = this;
NVIC_SetVector(USB0_IRQn, (uint32_t)&_usbisr);
NVIC_EnableIRQ(USB0_IRQn);
// USB Module Configuration
// Reset USB Module
USB0->USBTRC0 |= USB_USBTRC0_USBRESET_MASK;
while(USB0->USBTRC0 & USB_USBTRC0_USBRESET_MASK);
// Set BDT Base Register
USB0->BDTPAGE1=(uint8_t)((uint32_t)bdt>>8);
USB0->BDTPAGE2=(uint8_t)((uint32_t)bdt>>16);
USB0->BDTPAGE3=(uint8_t)((uint32_t)bdt>>24);
// Clear interrupt flag
USB0->ISTAT = 0xff;
// USB Interrupt Enablers
USB0->INTEN |= USB_INTEN_TOKDNEEN_MASK |
USB_INTEN_SOFTOKEN_MASK |
USB_INTEN_ERROREN_MASK |
USB_INTEN_USBRSTEN_MASK;
// Disable weak pull downs
USB0->USBCTRL &= ~(USB_USBCTRL_PDE_MASK | USB_USBCTRL_SUSP_MASK);
USB0->USBTRC0 |= 0x40;
}
USBHAL::~USBHAL(void) { }
void USBHAL::connect(void) {
// enable USB
USB0->CTL |= USB_CTL_USBENSOFEN_MASK;
// Pull up enable
USB0->CONTROL |= USB_CONTROL_DPPULLUPNONOTG_MASK;
}
void USBHAL::disconnect(void) {
// disable USB
USB0->CTL &= ~USB_CTL_USBENSOFEN_MASK;
// Pull up disable
USB0->CONTROL &= ~USB_CONTROL_DPPULLUPNONOTG_MASK;
}
void USBHAL::configureDevice(void) {
// not needed
}
void USBHAL::unconfigureDevice(void) {
// not needed
}
void USBHAL::setAddress(uint8_t address) {
// we don't set the address now otherwise the usb controller does not ack
// we set a flag instead
// see usbisr when an IN token is received
set_addr = 1;
addr = address;
}
bool USBHAL::realiseEndpoint(uint8_t endpoint, uint32_t maxPacket, uint32_t flags) {
uint32_t handshake_flag = 0;
uint8_t * buf;
if (endpoint > NUMBER_OF_PHYSICAL_ENDPOINTS - 1) {
return false;
}
uint32_t log_endpoint = PHY_TO_LOG(endpoint);
if ((flags & ISOCHRONOUS) == 0) {
handshake_flag = USB_ENDPT_EPHSHK_MASK;
if (IN_EP(endpoint))
buf = &endpoint_buffer[EP_BDT_IDX(log_endpoint, TX, ODD )][0];
else
buf = &endpoint_buffer[EP_BDT_IDX(log_endpoint, RX, ODD )][0];
} else {
if (IN_EP(endpoint))
buf = &endpoint_buffer_iso[2][0];
else
buf = &endpoint_buffer_iso[0][0];
}
// IN endpt -> device to host (TX)
if (IN_EP(endpoint)) {
USB0->ENDPOINT[log_endpoint].ENDPT |= handshake_flag | // ep handshaking (not if iso endpoint)
USB_ENDPT_EPTXEN_MASK; // en TX (IN) tran
bdt[EP_BDT_IDX(log_endpoint, TX, ODD )].address = (uint32_t) buf;
bdt[EP_BDT_IDX(log_endpoint, TX, EVEN)].address = 0;
}
// OUT endpt -> host to device (RX)
else {
USB0->ENDPOINT[log_endpoint].ENDPT |= handshake_flag | // ep handshaking (not if iso endpoint)
USB_ENDPT_EPRXEN_MASK; // en RX (OUT) tran.
bdt[EP_BDT_IDX(log_endpoint, RX, ODD )].byte_count = maxPacket;
bdt[EP_BDT_IDX(log_endpoint, RX, ODD )].address = (uint32_t) buf;
bdt[EP_BDT_IDX(log_endpoint, RX, ODD )].info = BD_OWN_MASK | BD_DTS_MASK;
bdt[EP_BDT_IDX(log_endpoint, RX, EVEN)].info = 0;
}
Data1 |= (1 << endpoint);
return true;
}
// read setup packet
void USBHAL::EP0setup(uint8_t *buffer) {
uint32_t sz;
endpointReadResult(EP0OUT, buffer, &sz);
}
void USBHAL::EP0readStage(void) {
Data1 &= ~1UL; // set DATA0
bdt[0].info = (BD_DTS_MASK | BD_OWN_MASK);
}
void USBHAL::EP0read(void) {
uint32_t idx = EP_BDT_IDX(PHY_TO_LOG(EP0OUT), RX, 0);
bdt[idx].byte_count = MAX_PACKET_SIZE_EP0;
}
uint32_t USBHAL::EP0getReadResult(uint8_t *buffer) {
uint32_t sz;
endpointReadResult(EP0OUT, buffer, &sz);
return sz;
}
void USBHAL::EP0write(uint8_t *buffer, uint32_t size) {
endpointWrite(EP0IN, buffer, size);
}
void USBHAL::EP0getWriteResult(void) {
}
void USBHAL::EP0stall(void) {
stallEndpoint(EP0OUT);
}
EP_STATUS USBHAL::endpointRead(uint8_t endpoint, uint32_t maximumSize) {
endpoint = PHY_TO_LOG(endpoint);
uint32_t idx = EP_BDT_IDX(endpoint, RX, 0);
bdt[idx].byte_count = maximumSize;
return EP_PENDING;
}
EP_STATUS USBHAL::endpointReadResult(uint8_t endpoint, uint8_t * buffer, uint32_t *bytesRead) {
uint32_t n, sz, idx, setup = 0;
uint8_t not_iso;
uint8_t * ep_buf;
uint32_t log_endpoint = PHY_TO_LOG(endpoint);
if (endpoint > NUMBER_OF_PHYSICAL_ENDPOINTS - 1) {
return EP_INVALID;
}
// if read on a IN endpoint -> error
if (IN_EP(endpoint)) {
return EP_INVALID;
}
idx = EP_BDT_IDX(log_endpoint, RX, 0);
sz = bdt[idx].byte_count;
not_iso = USB0->ENDPOINT[log_endpoint].ENDPT & USB_ENDPT_EPHSHK_MASK;
//for isochronous endpoint, we don't wait an interrupt
if ((log_endpoint != 0) && not_iso && !(epComplete & EP(endpoint))) {
return EP_PENDING;
}
if ((log_endpoint == 0) && (TOK_PID(idx) == SETUP_TOKEN)) {
setup = 1;
}
// non iso endpoint
if (not_iso) {
ep_buf = endpoint_buffer[idx];
} else {
ep_buf = endpoint_buffer_iso[0];
}
for (n = 0; n < sz; n++) {
buffer[n] = ep_buf[n];
}
if (((Data1 >> endpoint) & 1) == ((bdt[idx].info >> 6) & 1)) {
if (setup && (buffer[6] == 0)) // if no setup data stage,
Data1 &= ~1UL; // set DATA0
else
Data1 ^= (1 << endpoint);
}
if (((Data1 >> endpoint) & 1)) {
bdt[idx].info = BD_DTS_MASK | BD_DATA01_MASK | BD_OWN_MASK;
}
else {
bdt[idx].info = BD_DTS_MASK | BD_OWN_MASK;
}
USB0->CTL &= ~USB_CTL_TXSUSPENDTOKENBUSY_MASK;
*bytesRead = sz;
epComplete &= ~EP(endpoint);
return EP_COMPLETED;
}
EP_STATUS USBHAL::endpointWrite(uint8_t endpoint, uint8_t *data, uint32_t size) {
uint32_t idx, n;
uint8_t * ep_buf;
if (endpoint > NUMBER_OF_PHYSICAL_ENDPOINTS - 1) {
return EP_INVALID;
}
// if write on a OUT endpoint -> error
if (OUT_EP(endpoint)) {
return EP_INVALID;
}
idx = EP_BDT_IDX(PHY_TO_LOG(endpoint), TX, 0);
bdt[idx].byte_count = size;
// non iso endpoint
if (USB0->ENDPOINT[PHY_TO_LOG(endpoint)].ENDPT & USB_ENDPT_EPHSHK_MASK) {
ep_buf = endpoint_buffer[idx];
} else {
ep_buf = endpoint_buffer_iso[2];
}
for (n = 0; n < size; n++) {
ep_buf[n] = data[n];
}
if ((Data1 >> endpoint) & 1) {
bdt[idx].info = BD_OWN_MASK | BD_DTS_MASK;
} else {
bdt[idx].info = BD_OWN_MASK | BD_DTS_MASK | BD_DATA01_MASK;
}
Data1 ^= (1 << endpoint);
return EP_PENDING;
}
EP_STATUS USBHAL::endpointWriteResult(uint8_t endpoint) {
if (epComplete & EP(endpoint)) {
epComplete &= ~EP(endpoint);
return EP_COMPLETED;
}
return EP_PENDING;
}
void USBHAL::stallEndpoint(uint8_t endpoint) {
USB0->ENDPOINT[PHY_TO_LOG(endpoint)].ENDPT |= USB_ENDPT_EPSTALL_MASK;
}
void USBHAL::unstallEndpoint(uint8_t endpoint) {
USB0->ENDPOINT[PHY_TO_LOG(endpoint)].ENDPT &= ~USB_ENDPT_EPSTALL_MASK;
}
bool USBHAL::getEndpointStallState(uint8_t endpoint) {
uint8_t stall = (USB0->ENDPOINT[PHY_TO_LOG(endpoint)].ENDPT & USB_ENDPT_EPSTALL_MASK);
return (stall) ? true : false;
}
void USBHAL::remoteWakeup(void) {
// [TODO]
}
void USBHAL::_usbisr(void) {
instance->usbisr();
}
void USBHAL::usbisr(void) {
uint8_t i;
uint8_t istat = USB0->ISTAT;
// reset interrupt
if (istat & USB_ISTAT_USBRST_MASK) {
// disable all endpt
for(i = 0; i < 16; i++) {
USB0->ENDPOINT[i].ENDPT = 0x00;
}
// enable control endpoint
realiseEndpoint(EP0OUT, MAX_PACKET_SIZE_EP0, 0);
realiseEndpoint(EP0IN, MAX_PACKET_SIZE_EP0, 0);
Data1 = 0x55555555;
USB0->CTL |= USB_CTL_ODDRST_MASK;
USB0->ISTAT = 0xFF; // clear all interrupt status flags
USB0->ERRSTAT = 0xFF; // clear all error flags
USB0->ERREN = 0xFF; // enable error interrupt sources
USB0->ADDR = 0x00; // set default address
return;
}
// resume interrupt
if (istat & USB_ISTAT_RESUME_MASK) {
USB0->ISTAT = USB_ISTAT_RESUME_MASK;
}
// SOF interrupt
if (istat & USB_ISTAT_SOFTOK_MASK) {
USB0->ISTAT = USB_ISTAT_SOFTOK_MASK;
// SOF event, read frame number
SOF(frameNumber());
}
// stall interrupt
if (istat & 1<<7) {
if (USB0->ENDPOINT[0].ENDPT & USB_ENDPT_EPSTALL_MASK)
USB0->ENDPOINT[0].ENDPT &= ~USB_ENDPT_EPSTALL_MASK;
USB0->ISTAT |= USB_ISTAT_STALL_MASK;
}
// token interrupt
if (istat & 1<<3) {
uint32_t num = (USB0->STAT >> 4) & 0x0F;
uint32_t dir = (USB0->STAT >> 3) & 0x01;
uint32_t ev_odd = (USB0->STAT >> 2) & 0x01;
// setup packet
if ((num == 0) && (TOK_PID((EP_BDT_IDX(num, dir, ev_odd))) == SETUP_TOKEN)) {
Data1 &= ~0x02;
bdt[EP_BDT_IDX(0, TX, EVEN)].info &= ~BD_OWN_MASK;
bdt[EP_BDT_IDX(0, TX, ODD)].info &= ~BD_OWN_MASK;
// EP0 SETUP event (SETUP data received)
EP0setupCallback();
} else {
// OUT packet
if (TOK_PID((EP_BDT_IDX(num, dir, ev_odd))) == OUT_TOKEN) {
if (num == 0)
EP0out();
else {
epComplete |= (1 << EP(num));
if ((instance->*(epCallback[EP(num) - 2]))()) {
epComplete &= ~(1 << EP(num));
}
}
}
// IN packet
if (TOK_PID((EP_BDT_IDX(num, dir, ev_odd))) == IN_TOKEN) {
if (num == 0) {
EP0in();
if (set_addr == 1) {
USB0->ADDR = addr & 0x7F;
set_addr = 0;
}
}
else {
epComplete |= (1 << (EP(num) + 1));
if ((instance->*(epCallback[EP(num) + 1 - 2]))()) {
epComplete &= ~(1 << (EP(num) + 1));
}
}
}
}
USB0->ISTAT = USB_ISTAT_TOKDNE_MASK;
}
// sleep interrupt
if (istat & 1<<4) {
USB0->ISTAT |= USB_ISTAT_SLEEP_MASK;
}
// error interrupt
if (istat & USB_ISTAT_ERROR_MASK) {
USB0->ERRSTAT = 0xFF;
USB0->ISTAT |= USB_ISTAT_ERROR_MASK;
}
}
#endif