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eriknyquisteriknyquist
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Add IPM (Inter-Processor-Mailbox) driver to cores/arduino
This allows the mailbox to be used for Serial (instead of polling shared memory). The CurieMailbox library, in the codk-m-corelibs branch, will not require any API changes, but will now just be a thin wrapper around the methods in mailbox.cpp
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‎cores/arduino/mailbox.cpp‎

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#include <string.h>
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#include "interrupt.h"
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#include "scss_registers.h"
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#include "mailbox.h"
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#define CHANNEL_STS_MASK 0x1
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#define CHANNEL_INT_MASK 0x2
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#define CTRL_WORD_MASK 0x7FFFFFFF
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#define CHALL_STATUS_MASK 0xFFFF
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#define CHANNEL_STS_BITS (CHANNEL_STS_MASK | CHANNEL_INT_MASK)
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/* Mailbox channel status register */
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#define IO_REG_MAILBOX_CHALL_STS (SCSS_REGISTER_BASE + 0xAC0)
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typedef struct mbox_channel mbox_channel_t;
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typedef struct mbox_intmask mbox_intmask_t;
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/* Represents the registers for a single mailbox channel */
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struct mbox_channel {
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uint32_t ctrl;
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uint32_t data[CHANNEL_DATA_WORDS];
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uint32_t sts;
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};
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/* Mailbox interrupt mask; right now we only care about the
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* second byte, for SS mailbox interrupts (one bit per mailbox channel) */
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struct mbox_intmask {
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uint8_t lmt_intmask;
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uint8_t ss_intmask;
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uint8_t lmt_halt;
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uint8_t ss_halt;
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};
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static volatile mbox_intmask_t *intmask;
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static volatile mbox_channel_t *mbox;
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static void (*callbacks[NUM_MAILBOX_CHANNELS])(CurieMailboxMsg);
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void mailbox_register (int channel, void(*callback)(CurieMailboxMsg))
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{
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if (channel >= 0 && channel < NUM_MAILBOX_CHANNELS) {
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callbacks[channel] = callback;
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}
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}
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void mailbox_unregister (int channel)
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{
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if (channel >= 0 && channel < NUM_MAILBOX_CHANNELS) {
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callbacks[channel] = 0;
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}
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}
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void mailbox_disable_receive (int channel)
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{
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intmask->ss_intmask |= 1 << channel;
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}
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void mailbox_enable_receive (int channel)
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{
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intmask->ss_intmask &= ~(1 << channel);
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}
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static void do_callback (int channel, CurieMailboxMsg& msg)
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{
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void (*cb)(CurieMailboxMsg) = callbacks[channel];
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if (cb) {
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cb(msg);
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}
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}
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static void mailbox_read (int channel, CurieMailboxMsg& msg)
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{
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unsigned int i;
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/* Copy channel data into CurieMailboxMsg object */
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msg.id = mbox[channel].ctrl & CTRL_WORD_MASK;
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msg.channel = channel;
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for (i = 0; i < CHANNEL_DATA_WORDS; ++i) {
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msg.data[i] = mbox[channel].data[i];
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}
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/* Clear channel status & interrupt flags */
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mbox[channel].sts |= CHANNEL_STS_BITS;
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}
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void mailbox_write (CurieMailboxMsg& msg)
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{
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int i;
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uint32_t key;
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/* Can't write if channel status flag is set */
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while ((mbox[msg.channel].sts & CHANNEL_STS_MASK));
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key = interrupt_lock();
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/* Poplate channel payload */
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mbox[msg.channel].ctrl |= (msg.id & CTRL_WORD_MASK);
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for (i = 0; i < CHANNEL_DATA_WORDS; ++i) {
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mbox[msg.channel].data[i] = msg.data[i];
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}
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/* Trigger interupt to host */
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mbox[msg.channel].ctrl |= ~(CTRL_WORD_MASK);
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/* Wait for HW to set the channel status bit */
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while (!(mbox[msg.channel].sts & CHANNEL_STS_MASK));
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/* Wait for destination processor to clear channel status bit */
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while ((mbox[msg.channel].sts & CHANNEL_STS_MASK));
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interrupt_unlock(key);
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}
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static uint16_t get_chall_sts (void)
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{
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return MMIO_REG_VAL(IO_REG_MAILBOX_CHALL_STS) & CHALL_STATUS_MASK;
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}
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static void mailbox_isr (void)
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{
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int i;
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uint32_t sts;
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CurieMailboxMsg msg;
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sts = get_chall_sts();
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/* Get channel number */
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for (i = 0; i < NUM_MAILBOX_CHANNELS; ++i) {
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if (sts & (1 << (i * 2 + 1))) {
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break;
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}
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}
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mailbox_read(i, msg);
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do_callback(i, msg);
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}
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static void mailbox_hardware_init (void)
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{
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int i;
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for (i = 0; i < NUM_MAILBOX_CHANNELS; ++i) {
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mbox[i].sts &= ~(CHANNEL_STS_BITS);
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}
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}
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static void mailbox_interrupts_init (bool master)
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{
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interrupt_disable(SOC_MBOX_INTERRUPT);
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/* Mask SS mailbox interrupts for all channels;
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* Unmasking is done by enableReceive */
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intmask->ss_intmask = 0xFF;
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if (master) mailbox_hardware_init();
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interrupt_connect(SOC_MBOX_INTERRUPT, mailbox_isr);
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interrupt_enable(SOC_MBOX_INTERRUPT);
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}
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void mailbox_init (bool master)
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{
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intmask = (mbox_intmask_t *)IO_REG_MAILBOX_INT_MASK;
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mbox = (mbox_channel_t *)IO_REG_MAILBOX_BASE;
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memset(callbacks, 0, sizeof(callbacks));
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mailbox_interrupts_init(master);
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}

‎cores/arduino/mailbox.h‎

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#ifndef _MAILBOX_H_
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#define _MAILBOX_H_
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#define NUM_MAILBOX_CHANNELS 8
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#define CHANNEL_DATA_WORDS 4
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class CurieMailboxMsg {
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public:
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uint32_t data[CHANNEL_DATA_WORDS];
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uint32_t id;
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int channel = 0;
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};
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void mailbox_init (bool master);
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void mailbox_register (int channel, void(*callback)(CurieMailboxMsg));
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void mailbox_unregister (int channel);
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void mailbox_enable_receive (int channel);
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void mailbox_disable_receive (int channel);
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void mailbox_write(CurieMailboxMsg& msg);
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#endif

‎libraries/CurieMailbox/README.txt‎

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API reference:
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void CurieMailbox::begin (bool master)
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void CurieMailbox::begin ()
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Enable interrupts for the mailbox, and optionally initialise the
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mailbox hardware.
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Enable interrupts for the mailbox, and set up the mailbox hardware for use
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Params:
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bool master: flag indicating whether mailbox hardware should be initialised.
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The first processor to access the mailbox should do this; if in doubt, set
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to false (default is false, no initialisation).
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void CurieMailbox::begin (void)
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Enable interrupts for the mailbox, and do not initialise the hardware.
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Params:
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None.
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None
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void CurieMailbox::enableReceive (unsigned int channel)
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Params:
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int channel: integer value (0-7) representing the channel to be enabled.
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If the passed value does not represent a valid channel, then the highest
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channel will be used instead.
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int channel: integer value between 0 and CurieMailbox.numChannels,
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representing the channel to be enabled. If the passed value does not
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represent a valid channel, then the highest channel will be used instead.
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int CurieMailbox::available (void)

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