diff --git a/firmware/lib/can2040/COPYING b/firmware/lib/can2040/COPYING new file mode 100644 index 0000000..f288702 --- /dev/null +++ b/firmware/lib/can2040/COPYING @@ -0,0 +1,674 @@ + GNU GENERAL PUBLIC LICENSE + Version 3, 29 June 2007 + + Copyright (C) 2007 Free Software Foundation, Inc. + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + + Preamble + + The GNU General Public License is a free, copyleft license for +software and other kinds of works. + + The licenses for most software and other practical works are designed +to take away your freedom to share and change the works. By contrast, +the GNU General Public License is intended to guarantee your freedom to +share and change all versions of a program--to make sure it remains free +software for all its users. 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If not, see . + +Also add information on how to contact you by electronic and paper mail. + + If the program does terminal interaction, make it output a short +notice like this when it starts in an interactive mode: + + Copyright (C) + This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. + This is free software, and you are welcome to redistribute it + under certain conditions; type `show c' for details. + +The hypothetical commands `show w' and `show c' should show the appropriate +parts of the General Public License. Of course, your program's commands +might be different; for a GUI interface, you would use an "about box". + + You should also get your employer (if you work as a programmer) or school, +if any, to sign a "copyright disclaimer" for the program, if necessary. +For more information on this, and how to apply and follow the GNU GPL, see +. + + The GNU General Public License does not permit incorporating your program +into proprietary programs. If your program is a subroutine library, you +may consider it more useful to permit linking proprietary applications with +the library. If this is what you want to do, use the GNU Lesser General +Public License instead of this License. But first, please read +. diff --git a/firmware/lib/can2040/src/can2040.c b/firmware/lib/can2040/src/can2040.c new file mode 100644 index 0000000..7c4e09c --- /dev/null +++ b/firmware/lib/can2040/src/can2040.c @@ -0,0 +1,1371 @@ +// Software CANbus implementation for rp2040 +// +// Copyright (C) 2022,2023 Kevin O'Connor +// +// This file may be distributed under the terms of the GNU GPLv3 license. + +#include // uint32_t +#include // memset +// NOTE: This was changed from the original checkout +// #include "RP2040.h" // hw_set_bits +#include "hardware/address_mapped.h" // hw_set_bits +#include "can2040.h" // can2040_setup +#include "hardware/regs/dreq.h" // DREQ_PIO0_RX1 +#include "hardware/structs/dma.h" // dma_hw +#include "hardware/structs/iobank0.h" // iobank0_hw +#include "hardware/structs/padsbank0.h" // padsbank0_hw +#include "hardware/structs/pio.h" // pio0_hw +#include "hardware/structs/resets.h" // RESETS_RESET_PIO0_BITS + + +/**************************************************************** + * rp2040 and low-level helper functions + ****************************************************************/ + +// Helper compiler definitions +#define barrier() __asm__ __volatile__("": : :"memory") +#define likely(x) __builtin_expect(!!(x), 1) +#define unlikely(x) __builtin_expect(!!(x), 0) +#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) +#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d)) + +// Helper functions for writing to "io" memory +static inline void writel(void *addr, uint32_t val) { + barrier(); + *(volatile uint32_t *)addr = val; +} +static inline uint32_t readl(const void *addr) { + uint32_t val = *(volatile const uint32_t *)addr; + barrier(); + return val; +} + +// rp2040 helper function to clear a hardware reset bit +static void +rp2040_clear_reset(uint32_t reset_bit) +{ + if (resets_hw->reset & reset_bit) { + hw_clear_bits(&resets_hw->reset, reset_bit); + while (!(resets_hw->reset_done & reset_bit)) + ; + } +} + +// Helper to set the mode and extended function of a pin +static void +rp2040_gpio_peripheral(uint32_t gpio, int func, int pull_up) +{ + padsbank0_hw->io[gpio] = ( + PADS_BANK0_GPIO0_IE_BITS + | (PADS_BANK0_GPIO0_DRIVE_VALUE_4MA << PADS_BANK0_GPIO0_DRIVE_MSB) + | (pull_up > 0 ? PADS_BANK0_GPIO0_PUE_BITS : 0) + | (pull_up < 0 ? PADS_BANK0_GPIO0_PDE_BITS : 0)); + iobank0_hw->io[gpio].ctrl = func << IO_BANK0_GPIO0_CTRL_FUNCSEL_LSB; +} + + +/**************************************************************** + * rp2040 PIO support + ****************************************************************/ + +#define PIO_CLOCK_PER_BIT 32 +#define PIO_RX_WAKE_BITS 10 + +#define can2040_offset_sync_found_end_of_message 2u +#define can2040_offset_sync_signal_start 4u +#define can2040_offset_sync_entry 6u +#define can2040_offset_sync_end 13u +#define can2040_offset_shared_rx_read 13u +#define can2040_offset_shared_rx_end 15u +#define can2040_offset_match_load_next 18u +#define can2040_offset_tx_conflict 24u +#define can2040_offset_match_end 25u +#define can2040_offset_tx_got_recessive 25u +#define can2040_offset_tx_write_pin 27u + +static const uint16_t can2040_program_instructions[] = { + 0x0085, // 0: jmp y--, 5 + 0x0048, // 1: jmp x--, 8 + 0xe029, // 2: set x, 9 + 0x00cc, // 3: jmp pin, 12 + 0xc000, // 4: irq nowait 0 + 0x00c0, // 5: jmp pin, 0 + 0xc040, // 6: irq clear 0 + 0xe429, // 7: set x, 9 [4] + 0xf043, // 8: set y, 3 [16] + 0xc104, // 9: irq nowait 4 [1] + 0x03c5, // 10: jmp pin, 5 [3] + 0x0307, // 11: jmp 7 [3] + 0x0043, // 12: jmp x--, 3 + 0x20c4, // 13: wait 1 irq, 4 + 0x4001, // 14: in pins, 1 + 0xa046, // 15: mov y, isr + 0x01b2, // 16: jmp x != y, 18 [1] + 0xc002, // 17: irq nowait 2 + 0x40eb, // 18: in osr, 11 + 0x4054, // 19: in y, 20 + 0xa047, // 20: mov y, osr + 0x8080, // 21: pull noblock + 0xa027, // 22: mov x, osr + 0x0098, // 23: jmp y--, 24 + 0xa0e2, // 24: mov osr, y + 0x6021, // 25: out x, 1 + 0x00df, // 26: jmp pin, 31 + 0xb801, // 27: mov pins, x [24] + 0x02d9, // 28: jmp pin, 25 [2] + 0x0058, // 29: jmp x--, 24 + 0x6021, // 30: out x, 1 + 0x011b, // 31: jmp 27 [1] +}; + +// Local names for PIO state machine IRQs +#define SI_MAYTX PIO_IRQ0_INTE_SM0_BITS +#define SI_MATCHED PIO_IRQ0_INTE_SM2_BITS +#define SI_ACKDONE PIO_IRQ0_INTE_SM3_BITS +#define SI_RX_DATA PIO_IRQ0_INTE_SM1_RXNEMPTY_BITS +#define SI_TXPENDING PIO_IRQ0_INTE_SM1_BITS // Misc bit manually forced + +// Setup PIO "sync" state machine (state machine 0) +static void +pio_sync_setup(struct can2040 *cd) +{ + pio_hw_t *pio_hw = cd->pio_hw; + struct pio_sm_hw *sm = &pio_hw->sm[0]; + sm->execctrl = ( + cd->gpio_rx << PIO_SM0_EXECCTRL_JMP_PIN_LSB + | (can2040_offset_sync_end - 1) << PIO_SM0_EXECCTRL_WRAP_TOP_LSB + | can2040_offset_sync_signal_start << PIO_SM0_EXECCTRL_WRAP_BOTTOM_LSB); + sm->pinctrl = ( + 1 << PIO_SM0_PINCTRL_SET_COUNT_LSB + | cd->gpio_rx << PIO_SM0_PINCTRL_SET_BASE_LSB); + sm->instr = 0xe080; // set pindirs, 0 + sm->pinctrl = 0; + pio_hw->txf[0] = 9 + 6 * PIO_CLOCK_PER_BIT / 2; + sm->instr = 0x80a0; // pull block + sm->instr = can2040_offset_sync_entry; // jmp sync_entry +} + +// Setup PIO "rx" state machine (state machine 1) +static void +pio_rx_setup(struct can2040 *cd) +{ + pio_hw_t *pio_hw = cd->pio_hw; + struct pio_sm_hw *sm = &pio_hw->sm[1]; + sm->execctrl = ( + (can2040_offset_shared_rx_end - 1) << PIO_SM0_EXECCTRL_WRAP_TOP_LSB + | can2040_offset_shared_rx_read << PIO_SM0_EXECCTRL_WRAP_BOTTOM_LSB); + sm->pinctrl = cd->gpio_rx << PIO_SM0_PINCTRL_IN_BASE_LSB; + sm->shiftctrl = 0; // flush fifo on a restart + sm->shiftctrl = (PIO_SM0_SHIFTCTRL_FJOIN_RX_BITS + | PIO_RX_WAKE_BITS << PIO_SM0_SHIFTCTRL_PUSH_THRESH_LSB + | PIO_SM0_SHIFTCTRL_AUTOPUSH_BITS); + sm->instr = can2040_offset_shared_rx_read; // jmp shared_rx_read +} + +// Setup PIO "match" state machine (state machine 2) +static void +pio_match_setup(struct can2040 *cd) +{ + pio_hw_t *pio_hw = cd->pio_hw; + struct pio_sm_hw *sm = &pio_hw->sm[2]; + sm->execctrl = ( + (can2040_offset_match_end - 1) << PIO_SM0_EXECCTRL_WRAP_TOP_LSB + | can2040_offset_shared_rx_read << PIO_SM0_EXECCTRL_WRAP_BOTTOM_LSB); + sm->pinctrl = cd->gpio_rx << PIO_SM0_PINCTRL_IN_BASE_LSB; + sm->shiftctrl = 0; + sm->instr = 0xe040; // set y, 0 + sm->instr = 0xa0e2; // mov osr, y + sm->instr = 0xa02a, // mov x, !y + sm->instr = can2040_offset_match_load_next; // jmp match_load_next +} + +// Setup PIO "tx" state machine (state machine 3) +static void +pio_tx_setup(struct can2040 *cd) +{ + pio_hw_t *pio_hw = cd->pio_hw; + struct pio_sm_hw *sm = &pio_hw->sm[3]; + sm->execctrl = ( + cd->gpio_rx << PIO_SM0_EXECCTRL_JMP_PIN_LSB + | can2040_offset_tx_conflict << PIO_SM0_EXECCTRL_WRAP_TOP_LSB + | can2040_offset_tx_conflict << PIO_SM0_EXECCTRL_WRAP_BOTTOM_LSB); + sm->shiftctrl = (PIO_SM0_SHIFTCTRL_FJOIN_TX_BITS + | PIO_SM0_SHIFTCTRL_AUTOPULL_BITS); + sm->pinctrl = (1 << PIO_SM0_PINCTRL_SET_COUNT_LSB + | 1 << PIO_SM0_PINCTRL_OUT_COUNT_LSB + | cd->gpio_tx << PIO_SM0_PINCTRL_SET_BASE_LSB + | cd->gpio_tx << PIO_SM0_PINCTRL_OUT_BASE_LSB); + sm->instr = 0xe001; // set pins, 1 + sm->instr = 0xe081; // set pindirs, 1 +} + +// Set PIO "sync" machine to signal "may transmit" (sm irq 0) on 11 idle bits +static void +pio_sync_normal_start_signal(struct can2040 *cd) +{ + pio_hw_t *pio_hw = cd->pio_hw; + uint32_t eom_idx = can2040_offset_sync_found_end_of_message; + pio_hw->instr_mem[eom_idx] = 0xe12a; // set x, 10 [1] +} + +// Set PIO "sync" machine to signal "may transmit" (sm irq 0) on 17 idle bits +static void +pio_sync_slow_start_signal(struct can2040 *cd) +{ + pio_hw_t *pio_hw = cd->pio_hw; + uint32_t eom_idx = can2040_offset_sync_found_end_of_message; + pio_hw->instr_mem[eom_idx] = 0xa127; // mov x, osr [1] +} + +// Test if PIO "rx" state machine has overflowed its fifos +static int +pio_rx_check_stall(struct can2040 *cd) +{ + pio_hw_t *pio_hw = cd->pio_hw; + return pio_hw->fdebug & (1 << (PIO_FDEBUG_RXSTALL_LSB + 1)); +} + +// Set PIO "match" state machine to raise a "matched" signal on a bit sequence +static void +pio_match_check(struct can2040 *cd, uint32_t match_key) +{ + pio_hw_t *pio_hw = cd->pio_hw; + pio_hw->txf[2] = match_key; +} + +// Calculate pos+bits identifier for PIO "match" state machine +static uint32_t +pio_match_calc_key(uint32_t raw_bits, uint32_t rx_bit_pos) +{ + return (raw_bits & 0x1fffff) | ((-rx_bit_pos) << 21); +} + +// Cancel any pending checks on PIO "match" state machine +static void +pio_match_clear(struct can2040 *cd) +{ + pio_match_check(cd, 0); +} + +// Flush and halt PIO "tx" state machine +static void +pio_tx_reset(struct can2040 *cd) +{ + pio_hw_t *pio_hw = cd->pio_hw; + pio_hw->ctrl = 0x07 << PIO_CTRL_SM_ENABLE_LSB; + pio_hw->ctrl = ((0x07 << PIO_CTRL_SM_ENABLE_LSB) + | (0x08 << PIO_CTRL_SM_RESTART_LSB)); + pio_hw->irq = (SI_MATCHED | SI_ACKDONE) >> 8; // clear PIO irq flags + // Clear tx fifo + struct pio_sm_hw *sm = &pio_hw->sm[3]; + sm->shiftctrl = 0; + sm->shiftctrl = (PIO_SM0_SHIFTCTRL_FJOIN_TX_BITS + | PIO_SM0_SHIFTCTRL_AUTOPULL_BITS); +} + +// Queue a message for transmission on PIO "tx" state machine +static void +pio_tx_send(struct can2040 *cd, uint32_t *data, uint32_t count) +{ + pio_hw_t *pio_hw = cd->pio_hw; + pio_tx_reset(cd); + pio_hw->instr_mem[can2040_offset_tx_got_recessive] = 0x6021; // out x, 1 + uint32_t i; + for (i=0; itxf[3] = data[i]; + struct pio_sm_hw *sm = &pio_hw->sm[3]; + sm->instr = 0xe001; // set pins, 1 + sm->instr = 0x6021; // out x, 1 + sm->instr = can2040_offset_tx_write_pin; // jmp tx_write_pin + sm->instr = 0x20c0; // wait 1 irq, 0 + pio_hw->ctrl = 0x0f << PIO_CTRL_SM_ENABLE_LSB; +} + +// Set PIO "tx" state machine to inject an ack after a CRC match +static void +pio_tx_inject_ack(struct can2040 *cd, uint32_t match_key) +{ + pio_hw_t *pio_hw = cd->pio_hw; + pio_tx_reset(cd); + pio_hw->instr_mem[can2040_offset_tx_got_recessive] = 0xc023; // irq wait 3 + pio_hw->txf[3] = 0x7fffffff; + struct pio_sm_hw *sm = &pio_hw->sm[3]; + sm->instr = 0xe001; // set pins, 1 + sm->instr = 0x6021; // out x, 1 + sm->instr = can2040_offset_tx_write_pin; // jmp tx_write_pin + sm->instr = 0x20c2; // wait 1 irq, 2 + pio_hw->ctrl = 0x0f << PIO_CTRL_SM_ENABLE_LSB; + + pio_match_check(cd, match_key); +} + +// Did PIO "tx" state machine unexpectedly finish a transmit attempt? +static int +pio_tx_did_fail(struct can2040 *cd) +{ + pio_hw_t *pio_hw = cd->pio_hw; + // Check for passive/dominant bit conflict without parser noticing + if (pio_hw->sm[3].addr == can2040_offset_tx_conflict) + return !(pio_hw->intr & SI_RX_DATA); + // Check for unexpected drain of transmit queue without parser noticing + return (!(pio_hw->flevel & PIO_FLEVEL_TX3_BITS) + && (pio_hw->intr & (SI_MAYTX | SI_RX_DATA)) == SI_MAYTX); +} + +// Enable host irqs for state machine signals +static void +pio_irq_set(struct can2040 *cd, uint32_t sm_irqs) +{ + pio_hw_t *pio_hw = cd->pio_hw; + pio_hw->inte0 = sm_irqs | SI_RX_DATA; +} + +// Completely disable host irqs +static void +pio_irq_disable(struct can2040 *cd) +{ + pio_hw_t *pio_hw = cd->pio_hw; + pio_hw->inte0 = 0; +} + +// Return current host irq mask +static uint32_t +pio_irq_get(struct can2040 *cd) +{ + pio_hw_t *pio_hw = cd->pio_hw; + return pio_hw->inte0; +} + +// Raise the txpending flag +static void +pio_signal_set_txpending(struct can2040 *cd) +{ + pio_hw_t *pio_hw = cd->pio_hw; + pio_hw->irq_force = SI_TXPENDING >> 8; +} + +// Clear the txpending flag +static void +pio_signal_clear_txpending(struct can2040 *cd) +{ + pio_hw_t *pio_hw = cd->pio_hw; + pio_hw->irq = SI_TXPENDING >> 8; +} + +// Setup PIO state machines +static void +pio_sm_setup(struct can2040 *cd) +{ + // Reset state machines + pio_hw_t *pio_hw = cd->pio_hw; + pio_hw->ctrl = PIO_CTRL_SM_RESTART_BITS | PIO_CTRL_CLKDIV_RESTART_BITS; + pio_hw->fdebug = 0xffffffff; + pio_hw->irq = 0xff; + pio_signal_set_txpending(cd); + + // Load pio program + uint32_t i; + for (i=0; iinstr_mem[i] = can2040_program_instructions[i]; + + // Set initial state machine state + pio_sync_setup(cd); + pio_rx_setup(cd); + pio_match_setup(cd); + pio_tx_setup(cd); + + // Start state machines + pio_hw->ctrl = 0x07 << PIO_CTRL_SM_ENABLE_LSB; +} + +// Initial setup of gpio pins and PIO state machines +static void +pio_setup(struct can2040 *cd, uint32_t sys_clock, uint32_t bitrate) +{ + // Configure pio0 clock + uint32_t rb = cd->pio_num ? RESETS_RESET_PIO1_BITS : RESETS_RESET_PIO0_BITS; + rp2040_clear_reset(rb); + + // Setup and sync pio state machine clocks + pio_hw_t *pio_hw = cd->pio_hw; + uint32_t div = (256 / PIO_CLOCK_PER_BIT) * sys_clock / bitrate; + int i; + for (i=0; i<4; i++) + pio_hw->sm[i].clkdiv = div << PIO_SM0_CLKDIV_FRAC_LSB; + + // Configure state machines + pio_sm_setup(cd); + + // Map Rx/Tx gpios + uint32_t pio_func = cd->pio_num ? 7 : 6; + rp2040_gpio_peripheral(cd->gpio_rx, pio_func, 1); + rp2040_gpio_peripheral(cd->gpio_tx, pio_func, 0); +} + + +/**************************************************************** + * CRC calculation + ****************************************************************/ + +// Calculated 8-bit crc table (see scripts/crc.py) +static const uint16_t crc_table[256] = { + 0x0000,0x4599,0x4eab,0x0b32,0x58cf,0x1d56,0x1664,0x53fd,0x7407,0x319e, + 0x3aac,0x7f35,0x2cc8,0x6951,0x6263,0x27fa,0x2d97,0x680e,0x633c,0x26a5, + 0x7558,0x30c1,0x3bf3,0x7e6a,0x5990,0x1c09,0x173b,0x52a2,0x015f,0x44c6, + 0x4ff4,0x0a6d,0x5b2e,0x1eb7,0x1585,0x501c,0x03e1,0x4678,0x4d4a,0x08d3, + 0x2f29,0x6ab0,0x6182,0x241b,0x77e6,0x327f,0x394d,0x7cd4,0x76b9,0x3320, + 0x3812,0x7d8b,0x2e76,0x6bef,0x60dd,0x2544,0x02be,0x4727,0x4c15,0x098c, + 0x5a71,0x1fe8,0x14da,0x5143,0x73c5,0x365c,0x3d6e,0x78f7,0x2b0a,0x6e93, + 0x65a1,0x2038,0x07c2,0x425b,0x4969,0x0cf0,0x5f0d,0x1a94,0x11a6,0x543f, + 0x5e52,0x1bcb,0x10f9,0x5560,0x069d,0x4304,0x4836,0x0daf,0x2a55,0x6fcc, + 0x64fe,0x2167,0x729a,0x3703,0x3c31,0x79a8,0x28eb,0x6d72,0x6640,0x23d9, + 0x7024,0x35bd,0x3e8f,0x7b16,0x5cec,0x1975,0x1247,0x57de,0x0423,0x41ba, + 0x4a88,0x0f11,0x057c,0x40e5,0x4bd7,0x0e4e,0x5db3,0x182a,0x1318,0x5681, + 0x717b,0x34e2,0x3fd0,0x7a49,0x29b4,0x6c2d,0x671f,0x2286,0x2213,0x678a, + 0x6cb8,0x2921,0x7adc,0x3f45,0x3477,0x71ee,0x5614,0x138d,0x18bf,0x5d26, + 0x0edb,0x4b42,0x4070,0x05e9,0x0f84,0x4a1d,0x412f,0x04b6,0x574b,0x12d2, + 0x19e0,0x5c79,0x7b83,0x3e1a,0x3528,0x70b1,0x234c,0x66d5,0x6de7,0x287e, + 0x793d,0x3ca4,0x3796,0x720f,0x21f2,0x646b,0x6f59,0x2ac0,0x0d3a,0x48a3, + 0x4391,0x0608,0x55f5,0x106c,0x1b5e,0x5ec7,0x54aa,0x1133,0x1a01,0x5f98, + 0x0c65,0x49fc,0x42ce,0x0757,0x20ad,0x6534,0x6e06,0x2b9f,0x7862,0x3dfb, + 0x36c9,0x7350,0x51d6,0x144f,0x1f7d,0x5ae4,0x0919,0x4c80,0x47b2,0x022b, + 0x25d1,0x6048,0x6b7a,0x2ee3,0x7d1e,0x3887,0x33b5,0x762c,0x7c41,0x39d8, + 0x32ea,0x7773,0x248e,0x6117,0x6a25,0x2fbc,0x0846,0x4ddf,0x46ed,0x0374, + 0x5089,0x1510,0x1e22,0x5bbb,0x0af8,0x4f61,0x4453,0x01ca,0x5237,0x17ae, + 0x1c9c,0x5905,0x7eff,0x3b66,0x3054,0x75cd,0x2630,0x63a9,0x689b,0x2d02, + 0x276f,0x62f6,0x69c4,0x2c5d,0x7fa0,0x3a39,0x310b,0x7492,0x5368,0x16f1, + 0x1dc3,0x585a,0x0ba7,0x4e3e,0x450c,0x0095 +}; + +// Update a crc with 8 bits of data +static uint32_t +crc_byte(uint32_t crc, uint32_t data) +{ + return (crc << 8) ^ crc_table[((crc >> 7) ^ data) & 0xff]; +} + +// Update a crc with 8, 16, 24, or 32 bits of data +static inline uint32_t +crc_bytes(uint32_t crc, uint32_t data, uint32_t num) +{ + switch (num) { + default: crc = crc_byte(crc, data >> 24); /* FALLTHRU */ + case 3: crc = crc_byte(crc, data >> 16); /* FALLTHRU */ + case 2: crc = crc_byte(crc, data >> 8); /* FALLTHRU */ + case 1: crc = crc_byte(crc, data); + } + return crc; +} + + +/**************************************************************** + * Bit unstuffing + ****************************************************************/ + +// Add 'count' number of bits from 'data' to the 'bu' unstuffer +static void +unstuf_add_bits(struct can2040_bitunstuffer *bu, uint32_t data, uint32_t count) +{ + uint32_t mask = (1 << count) - 1; + bu->stuffed_bits = (bu->stuffed_bits << count) | (data & mask); + bu->count_stuff = count; +} + +// Reset state and set the next desired 'num_bits' unstuffed bits to extract +static void +unstuf_set_count(struct can2040_bitunstuffer *bu, uint32_t num_bits) +{ + bu->unstuffed_bits = 0; + bu->count_unstuff = num_bits; +} + +// Clear bitstuffing state (used after crc field to avoid bitstuffing ack field) +static void +unstuf_clear_state(struct can2040_bitunstuffer *bu) +{ + uint32_t lb = 1 << bu->count_stuff; + bu->stuffed_bits = (bu->stuffed_bits & (lb - 1)) | (lb << 1); +} + +// Restore raw bitstuffing state (used to undo unstuf_clear_state() ) +static void +unstuf_restore_state(struct can2040_bitunstuffer *bu, uint32_t data) +{ + uint32_t cs = bu->count_stuff; + bu->stuffed_bits = (bu->stuffed_bits & ((1 << cs) - 1)) | (data << cs); +} + +// Pull bits from unstuffer (as specified in unstuf_set_count() ) +static int +unstuf_pull_bits(struct can2040_bitunstuffer *bu) +{ + uint32_t sb = bu->stuffed_bits, edges = sb ^ (sb >> 1); + uint32_t e2 = edges | (edges >> 1), e4 = e2 | (e2 >> 2), rm_bits = ~e4; + uint32_t cs = bu->count_stuff, cu = bu->count_unstuff; + if (!cs) + // Need more data + return 1; + for (;;) { + uint32_t try_cnt = cs > cu ? cu : cs; + for (;;) { + uint32_t try_mask = ((1 << try_cnt) - 1) << (cs + 1 - try_cnt); + if (likely(!(rm_bits & try_mask))) { + // No stuff bits in try_cnt bits - copy into unstuffed_bits + bu->count_unstuff = cu = cu - try_cnt; + bu->count_stuff = cs = cs - try_cnt; + bu->unstuffed_bits |= ((sb >> cs) & ((1 << try_cnt) - 1)) << cu; + if (! cu) + // Extracted desired bits + return 0; + break; + } + bu->count_stuff = cs = cs - 1; + if (rm_bits & (1 << (cs + 1))) { + // High bit is a stuff bit + if (unlikely(rm_bits & (1 << cs))) { + // Six consecutive bits - a bitstuff error + if (sb & (1 << cs)) + return -1; + return -2; + } + break; + } + // High bit not a stuff bit - limit try_cnt and retry + bu->count_unstuff = cu = cu - 1; + bu->unstuffed_bits |= ((sb >> cs) & 1) << cu; + try_cnt /= 2; + } + if (likely(!cs)) + // Need more data + return 1; + } +} + +// Return most recent raw (still stuffed) bits +static uint32_t +unstuf_get_raw(struct can2040_bitunstuffer *bu) +{ + return bu->stuffed_bits >> bu->count_stuff; +} + + +/**************************************************************** + * Bit stuffing + ****************************************************************/ + +// Stuff 'num_bits' bits in '*pb' - upper bits must already be stuffed +static uint32_t +bitstuff(uint32_t *pb, uint32_t num_bits) +{ + uint32_t b = *pb, count = num_bits; + for (;;) { + uint32_t try_cnt = num_bits, edges = b ^ (b >> 1); + uint32_t e2 = edges | (edges >> 1), e4 = e2 | (e2 >> 2), add_bits = ~e4; + for (;;) { + uint32_t try_mask = ((1 << try_cnt) - 1) << (num_bits - try_cnt); + if (!(add_bits & try_mask)) { + // No stuff bits needed in try_cnt bits + if (try_cnt >= num_bits) + goto done; + num_bits -= try_cnt; + try_cnt = (num_bits + 1) / 2; + continue; + } + if (add_bits & (1 << (num_bits - 1))) { + // A stuff bit must be inserted prior to the high bit + uint32_t low_mask = (1 << num_bits) - 1, low = b & low_mask; + uint32_t high = (b & ~(low_mask >> 1)) << 1; + b = high ^ low ^ (1 << (num_bits - 1)); + count += 1; + if (num_bits <= 4) + goto done; + num_bits -= 4; + break; + } + // High bit doesn't need stuff bit - accept it, limit try_cnt, retry + num_bits--; + try_cnt /= 2; + } + } +done: + *pb = b; + return count; +} + +// State storage for building bit stuffed transmit messages +struct bitstuffer_s { + uint32_t prev_stuffed, bitpos, *buf; +}; + +// Push 'count' bits of 'data' into stuffer without performing bit stuffing +static void +bs_pushraw(struct bitstuffer_s *bs, uint32_t data, uint32_t count) +{ + uint32_t bitpos = bs->bitpos; + uint32_t wp = bitpos / 32, bitused = bitpos % 32, bitavail = 32 - bitused; + uint32_t *fb = &bs->buf[wp]; + if (bitavail >= count) { + fb[0] |= data << (bitavail - count); + } else { + fb[0] |= data >> (count - bitavail); + fb[1] |= data << (32 - (count - bitavail)); + } + bs->bitpos = bitpos + count; +} + +// Push 'count' bits of 'data' into stuffer +static void +bs_push(struct bitstuffer_s *bs, uint32_t data, uint32_t count) +{ + data &= (1 << count) - 1; + uint32_t stuf = (bs->prev_stuffed << count) | data; + uint32_t newcount = bitstuff(&stuf, count); + bs_pushraw(bs, stuf, newcount); + bs->prev_stuffed = stuf; +} + +// Pad final word of stuffer with high bits +static uint32_t +bs_finalize(struct bitstuffer_s *bs) +{ + uint32_t bitpos = bs->bitpos; + uint32_t words = DIV_ROUND_UP(bitpos, 32); + uint32_t extra = words * 32 - bitpos; + if (extra) + bs->buf[words - 1] |= (1 << extra) - 1; + return words; +} + + +/**************************************************************** + * Transmit state tracking + ****************************************************************/ + +// Transmit states (stored in cd->tx_state) +enum { + TS_IDLE = 0, TS_QUEUED = 1, TS_ACKING_RX = 2, TS_CONFIRM_TX = 3 +}; + +// Calculate queue array position from a transmit index +static uint32_t +tx_qpos(struct can2040 *cd, uint32_t pos) +{ + return pos % ARRAY_SIZE(cd->tx_queue); +} + +// Queue the next message for transmission in the PIO +static uint32_t +tx_schedule_transmit(struct can2040 *cd) +{ + if (cd->tx_state == TS_QUEUED && !pio_tx_did_fail(cd)) + // Already queued or actively transmitting + return 0; + uint32_t tx_pull_pos = cd->tx_pull_pos; + if (readl(&cd->tx_push_pos) == tx_pull_pos) { + // No new messages to transmit + cd->tx_state = TS_IDLE; + pio_signal_clear_txpending(cd); + __DMB(); + if (likely(readl(&cd->tx_push_pos) == tx_pull_pos)) + return SI_TXPENDING; + // Raced with can2040_transmit() - msg is now available for transmit + pio_signal_set_txpending(cd); + } + cd->tx_state = TS_QUEUED; + cd->stats.tx_attempt++; + struct can2040_transmit *qt = &cd->tx_queue[tx_qpos(cd, tx_pull_pos)]; + pio_tx_send(cd, qt->stuffed_data, qt->stuffed_words); + return 0; +} + +// Setup PIO state for ack injection +static void +tx_inject_ack(struct can2040 *cd, uint32_t match_key) +{ + cd->tx_state = TS_ACKING_RX; + pio_tx_inject_ack(cd, match_key); +} + +// Check if the current parsed message is feedback from current transmit +static int +tx_check_local_message(struct can2040 *cd) +{ + if (cd->tx_state != TS_QUEUED) + return 0; + struct can2040_transmit *qt = &cd->tx_queue[tx_qpos(cd, cd->tx_pull_pos)]; + struct can2040_msg *pm = &cd->parse_msg, *tm = &qt->msg; + if (tm->id == pm->id) { + if (qt->crc != cd->parse_crc || tm->dlc != pm->dlc + || tm->data32[0] != pm->data32[0] || tm->data32[1] != pm->data32[1]) + // Message with same id that differs in content - an error + return -1; + // This is a self transmit + cd->tx_state = TS_CONFIRM_TX; + return 1; + } + return 0; +} + + +/**************************************************************** + * Notification callbacks + ****************************************************************/ + +// Report state flags (stored in cd->report_state) +enum { + RS_NEED_EOF_FLAG = 1<<2, + // States + RS_IDLE = 0, RS_NEED_RX_ACK = 1, RS_NEED_TX_ACK = 2, + RS_NEED_RX_EOF = RS_NEED_RX_ACK | RS_NEED_EOF_FLAG, + RS_NEED_TX_EOF = RS_NEED_TX_ACK | RS_NEED_EOF_FLAG, +}; + +// Report error to calling code (via callback interface) +static void +report_callback_error(struct can2040 *cd, uint32_t error_code) +{ + struct can2040_msg msg = {}; + cd->rx_cb(cd, CAN2040_NOTIFY_ERROR | error_code, &msg); +} + +// Report a received message to calling code (via callback interface) +static void +report_callback_rx_msg(struct can2040 *cd) +{ + cd->stats.rx_total++; + cd->rx_cb(cd, CAN2040_NOTIFY_RX, &cd->parse_msg); +} + +// Report a message that was successfully transmited (via callback interface) +static void +report_callback_tx_msg(struct can2040 *cd) +{ + writel(&cd->tx_pull_pos, cd->tx_pull_pos + 1); + cd->stats.tx_total++; + cd->rx_cb(cd, CAN2040_NOTIFY_TX, &cd->parse_msg); +} + +// EOF phase complete - report message (rx or tx) to calling code +static void +report_handle_eof(struct can2040 *cd) +{ + if (cd->report_state & RS_NEED_EOF_FLAG) { // RS_NEED_xX_EOF + // Successfully processed a new message - report to calling code + pio_sync_normal_start_signal(cd); + if (cd->report_state == RS_NEED_TX_EOF) + report_callback_tx_msg(cd); + else + report_callback_rx_msg(cd); + } + cd->report_state = RS_IDLE; + pio_match_clear(cd); +} + +// Check if message being processed is an rx message (not self feedback from tx) +static int +report_is_not_in_tx(struct can2040 *cd) +{ + return !(cd->report_state & RS_NEED_TX_ACK); +} + +// Parser found a new message start +static void +report_note_message_start(struct can2040 *cd) +{ + pio_irq_set(cd, SI_MAYTX); +} + +// Setup for ack injection (if receiving) or ack confirmation (if transmit) +static int +report_note_crc_start(struct can2040 *cd) +{ + int ret = tx_check_local_message(cd); + if (ret) { + if (ret < 0) + return -1; + // This is a self transmit - setup tx eof "matched" signal + cd->report_state = RS_NEED_TX_ACK; + uint32_t bits = (cd->parse_crc_bits << 9) | 0x0ff; + pio_match_check(cd, pio_match_calc_key(bits, cd->parse_crc_pos + 9)); + return 0; + } + + // Setup for ack inject (after rx fifos fully drained) + cd->report_state = RS_NEED_RX_ACK; + pio_signal_set_txpending(cd); + pio_irq_set(cd, SI_MAYTX | SI_TXPENDING); + return 0; +} + +// Parser successfully found matching crc +static void +report_note_crc_success(struct can2040 *cd) +{ + if (cd->report_state == RS_NEED_TX_ACK) + // Enable "matched" irq for fast back-to-back transmit scheduling + pio_irq_set(cd, SI_MAYTX | SI_MATCHED); +} + +// Parser found successful ack +static void +report_note_ack_success(struct can2040 *cd) +{ + if (cd->report_state == RS_IDLE) + // Got "matched" signal already + return; + // Transition RS_NEED_xX_ACK to RS_NEED_xX_EOF + cd->report_state |= RS_NEED_EOF_FLAG; +} + +// Parser found successful EOF +static void +report_note_eof_success(struct can2040 *cd) +{ + if (cd->report_state == RS_IDLE) + // Got "matched" signal already + return; + report_handle_eof(cd); + pio_irq_set(cd, SI_TXPENDING); +} + +// Parser found unexpected data on input +static void +report_note_discarding(struct can2040 *cd) +{ + if (cd->report_state != RS_IDLE) { + cd->report_state = RS_IDLE; + pio_match_clear(cd); + } + pio_sync_slow_start_signal(cd); + pio_irq_set(cd, SI_MAYTX | SI_TXPENDING); +} + +// Received PIO rx "ackdone" irq +static void +report_line_ackdone(struct can2040 *cd) +{ + // Setup "matched" irq for fast rx callbacks + uint32_t bits = (cd->parse_crc_bits << 8) | 0x7f; + pio_match_check(cd, pio_match_calc_key(bits, cd->parse_crc_pos + 8)); + // Schedule next transmit (so it is ready for next frame line arbitration) + uint32_t check_txpending = tx_schedule_transmit(cd); + pio_irq_set(cd, SI_MAYTX | SI_MATCHED | check_txpending); +} + +// Received PIO "matched" irq +static void +report_line_matched(struct can2040 *cd) +{ + // A match event indicates an ack and eof are present + if (cd->report_state != RS_IDLE) { + // Transition RS_NEED_xX_ACK to RS_NEED_xX_EOF (if not already there) + cd->report_state |= RS_NEED_EOF_FLAG; + report_handle_eof(cd); + } + // Implement fast back-to-back tx scheduling (if applicable) + uint32_t check_txpending = tx_schedule_transmit(cd); + pio_irq_set(cd, check_txpending); +} + +// Received 10+ passive bits on the line (between 10 and 17 bits) +static void +report_line_maytx(struct can2040 *cd) +{ + // Line is idle - may be unexpected EOF, missed ack injection, + // or missed "matched" signal. + if (cd->report_state != RS_IDLE) + report_handle_eof(cd); + uint32_t check_txpending = tx_schedule_transmit(cd); + pio_irq_set(cd, check_txpending); +} + +// Schedule a transmit +static void +report_line_txpending(struct can2040 *cd) +{ + uint32_t pio_irqs = pio_irq_get(cd); + if (pio_irqs == (SI_MAYTX | SI_TXPENDING | SI_RX_DATA) + && cd->report_state == RS_NEED_RX_ACK) { + // Ack inject request from report_note_crc_start() + uint32_t mk = pio_match_calc_key(cd->parse_crc_bits, cd->parse_crc_pos); + tx_inject_ack(cd, mk); + pio_irq_set(cd, SI_MAYTX | SI_ACKDONE); + return; + } + // Tx request from can2040_transmit(), report_note_eof_success(), + // or report_note_discarding(). + uint32_t check_txpending = tx_schedule_transmit(cd); + pio_irq_set(cd, (pio_irqs & ~SI_TXPENDING) | check_txpending); +} + + +/**************************************************************** + * Input state tracking + ****************************************************************/ + +// Parsing states (stored in cd->parse_state) +enum { + MS_START, MS_HEADER, MS_EXT_HEADER, MS_DATA0, MS_DATA1, + MS_CRC, MS_ACK, MS_EOF0, MS_EOF1, MS_DISCARD +}; + +// Reset any bits in the incoming parsing state +static void +data_state_clear_bits(struct can2040 *cd) +{ + cd->raw_bit_count = cd->unstuf.stuffed_bits = cd->unstuf.count_stuff = 0; +} + +// Transition to the next parsing state +static void +data_state_go_next(struct can2040 *cd, uint32_t state, uint32_t num_bits) +{ + cd->parse_state = state; + unstuf_set_count(&cd->unstuf, num_bits); +} + +// Transition to the MS_DISCARD state - drop all bits until 6 passive bits +static void +data_state_go_discard(struct can2040 *cd) +{ + if (pio_rx_check_stall(cd)) { + // CPU couldn't keep up for some read data - must reset pio state + data_state_clear_bits(cd); + pio_sm_setup(cd); + report_callback_error(cd, 0); + } + + data_state_go_next(cd, MS_DISCARD, 32); + + // Clear report state and update hw irqs after transition to MS_DISCARD + report_note_discarding(cd); +} + +// Note a data parse error and transition to discard state +static void +data_state_go_error(struct can2040 *cd) +{ + cd->stats.parse_error++; + data_state_go_discard(cd); +} + +// Received six dominant bits on the line +static void +data_state_line_error(struct can2040 *cd) +{ + if (cd->parse_state == MS_DISCARD) + data_state_go_discard(cd); + else + data_state_go_error(cd); +} + +// Received six unexpected passive bits on the line +static void +data_state_line_passive(struct can2040 *cd) +{ + if (cd->parse_state != MS_DISCARD && cd->parse_state != MS_START) { + // Bitstuff error + data_state_go_error(cd); + return; + } + + uint32_t stuffed_bits = unstuf_get_raw(&cd->unstuf); + uint32_t dom_bits = ~stuffed_bits; + if (!dom_bits) { + // Counter overflow in "sync" state machine - reset it + data_state_clear_bits(cd); + pio_sm_setup(cd); + data_state_go_discard(cd); + return; + } + + // Look for sof after 10 passive bits (most "PIO sync" will produce) + if (!(dom_bits & 0x3ff)) { + data_state_go_next(cd, MS_START, 1); + return; + } + + data_state_go_discard(cd); +} + +// Transition to MS_CRC state - await 16 bits of crc +static void +data_state_go_crc(struct can2040 *cd) +{ + cd->parse_crc &= 0x7fff; + + // Calculate raw stuffed bits after crc and crc delimiter + uint32_t crcstart_bitpos = cd->raw_bit_count - cd->unstuf.count_stuff - 1; + uint32_t crc_bits = (unstuf_get_raw(&cd->unstuf) << 15) | cd->parse_crc; + uint32_t crc_bitcount = bitstuff(&crc_bits, 15 + 1) - 1; + cd->parse_crc_bits = (crc_bits << 1) | 0x01; // Add crc delimiter + cd->parse_crc_pos = crcstart_bitpos + crc_bitcount + 1; + + int ret = report_note_crc_start(cd); + if (ret) { + data_state_go_error(cd); + return; + } + data_state_go_next(cd, MS_CRC, 16); +} + +// Transition to MS_DATA0 state (if applicable) - await data bits +static void +data_state_go_data(struct can2040 *cd, uint32_t id, uint32_t data) +{ + if (data & (0x03 << 4)) { + // Not a supported header + data_state_go_discard(cd); + return; + } + cd->parse_msg.data32[0] = cd->parse_msg.data32[1] = 0; + uint32_t dlc = data & 0x0f; + cd->parse_msg.dlc = dlc; + if (data & (1 << 6)) { + dlc = 0; + id |= CAN2040_ID_RTR; + } + cd->parse_msg.id = id; + if (dlc) + data_state_go_next(cd, MS_DATA0, dlc >= 4 ? 32 : dlc * 8); + else + data_state_go_crc(cd); +} + +// Handle reception of first bit of header (after start-of-frame (SOF)) +static void +data_state_update_start(struct can2040 *cd, uint32_t data) +{ + cd->parse_msg.id = data; + report_note_message_start(cd); + data_state_go_next(cd, MS_HEADER, 17); +} + +// Handle reception of next 17 header bits +static void +data_state_update_header(struct can2040 *cd, uint32_t data) +{ + data |= cd->parse_msg.id << 17; + if ((data & 0x60) == 0x60) { + // Extended header + cd->parse_msg.id = data; + data_state_go_next(cd, MS_EXT_HEADER, 20); + return; + } + cd->parse_crc = crc_bytes(0, data, 3); + data_state_go_data(cd, (data >> 7) & 0x7ff, data); +} + +// Handle reception of additional 20 bits of "extended header" +static void +data_state_update_ext_header(struct can2040 *cd, uint32_t data) +{ + uint32_t hdr1 = cd->parse_msg.id; + uint32_t crc = crc_bytes(0, hdr1 >> 4, 2); + cd->parse_crc = crc_bytes(crc, ((hdr1 & 0x0f) << 20) | data, 3); + uint32_t id = (((hdr1 << 11) & 0x1ffc0000) | ((hdr1 << 13) & 0x3e000) + | (data >> 7) | CAN2040_ID_EFF); + data_state_go_data(cd, id, data); +} + +// Handle reception of first 1-4 bytes of data content +static void +data_state_update_data0(struct can2040 *cd, uint32_t data) +{ + uint32_t dlc = cd->parse_msg.dlc, bits = dlc >= 4 ? 32 : dlc * 8; + cd->parse_crc = crc_bytes(cd->parse_crc, data, dlc); + cd->parse_msg.data32[0] = __builtin_bswap32(data << (32 - bits)); + if (dlc > 4) + data_state_go_next(cd, MS_DATA1, dlc >= 8 ? 32 : (dlc - 4) * 8); + else + data_state_go_crc(cd); +} + +// Handle reception of bytes 5-8 of data content +static void +data_state_update_data1(struct can2040 *cd, uint32_t data) +{ + uint32_t dlc = cd->parse_msg.dlc, bits = dlc >= 8 ? 32 : (dlc - 4) * 8; + cd->parse_crc = crc_bytes(cd->parse_crc, data, dlc - 4); + cd->parse_msg.data32[1] = __builtin_bswap32(data << (32 - bits)); + data_state_go_crc(cd); +} + +// Handle reception of 16 bits of message CRC (15 crc bits + crc delimiter) +static void +data_state_update_crc(struct can2040 *cd, uint32_t data) +{ + if (((cd->parse_crc << 1) | 1) != data) { + data_state_go_error(cd); + return; + } + + report_note_crc_success(cd); + unstuf_clear_state(&cd->unstuf); + data_state_go_next(cd, MS_ACK, 2); +} + +// Handle reception of 2 bits of ack phase (ack, ack delimiter) +static void +data_state_update_ack(struct can2040 *cd, uint32_t data) +{ + if (data != 0x01) { + // Undo unstuf_clear_state() for correct SOF detection in + // data_state_line_passive() + unstuf_restore_state(&cd->unstuf, (cd->parse_crc_bits << 2) | data); + + data_state_go_error(cd); + return; + } + report_note_ack_success(cd); + data_state_go_next(cd, MS_EOF0, 4); +} + +// Handle reception of first four end-of-frame (EOF) bits +static void +data_state_update_eof0(struct can2040 *cd, uint32_t data) +{ + if (data != 0x0f || pio_rx_check_stall(cd)) { + data_state_go_error(cd); + return; + } + unstuf_clear_state(&cd->unstuf); + data_state_go_next(cd, MS_EOF1, 5); +} + +// Handle reception of end-of-frame (EOF) bits 5-7 and first two IFS bits +static void +data_state_update_eof1(struct can2040 *cd, uint32_t data) +{ + if (data == 0x1f) { + // Success + report_note_eof_success(cd); + data_state_go_next(cd, MS_START, 1); + } else if (data >= 0x1c || (data >= 0x18 && report_is_not_in_tx(cd))) { + // Message fully transmitted - followed by "overload frame" + report_note_eof_success(cd); + data_state_go_discard(cd); + } else { + data_state_go_error(cd); + } +} + +// Handle data received while in MS_DISCARD state +static void +data_state_update_discard(struct can2040 *cd, uint32_t data) +{ + data_state_go_discard(cd); +} + +// Update parsing state after reading the bits of the current field +static void +data_state_update(struct can2040 *cd, uint32_t data) +{ + switch (cd->parse_state) { + case MS_START: data_state_update_start(cd, data); break; + case MS_HEADER: data_state_update_header(cd, data); break; + case MS_EXT_HEADER: data_state_update_ext_header(cd, data); break; + case MS_DATA0: data_state_update_data0(cd, data); break; + case MS_DATA1: data_state_update_data1(cd, data); break; + case MS_CRC: data_state_update_crc(cd, data); break; + case MS_ACK: data_state_update_ack(cd, data); break; + case MS_EOF0: data_state_update_eof0(cd, data); break; + case MS_EOF1: data_state_update_eof1(cd, data); break; + case MS_DISCARD: data_state_update_discard(cd, data); break; + } +} + + +/**************************************************************** + * Input processing + ****************************************************************/ + +// Process incoming data from PIO "rx" state machine +static void +process_rx(struct can2040 *cd, uint32_t rx_data) +{ + unstuf_add_bits(&cd->unstuf, rx_data, PIO_RX_WAKE_BITS); + cd->raw_bit_count += PIO_RX_WAKE_BITS; + + // undo bit stuffing + for (;;) { + int ret = unstuf_pull_bits(&cd->unstuf); + if (likely(ret > 0)) { + // Need more data + break; + } else if (likely(!ret)) { + // Pulled the next field - process it + data_state_update(cd, cd->unstuf.unstuffed_bits); + } else { + if (ret == -1) + // 6 consecutive high bits + data_state_line_passive(cd); + else + // 6 consecutive low bits + data_state_line_error(cd); + } + } +} + +// Main API irq notification function +void +can2040_pio_irq_handler(struct can2040 *cd) +{ + pio_hw_t *pio_hw = cd->pio_hw; + uint32_t ints = pio_hw->ints0; + while (likely(ints & SI_RX_DATA)) { + uint32_t rx_data = pio_hw->rxf[1]; + process_rx(cd, rx_data); + ints = pio_hw->ints0; + if (likely(!ints)) + return; + } + + if (ints & SI_ACKDONE) + // Ack of received message completed successfully + report_line_ackdone(cd); + else if (ints & SI_MATCHED) + // Transmit message completed successfully + report_line_matched(cd); + else if (ints & SI_MAYTX) + // Bus is idle, but not all bits may have been flushed yet + report_line_maytx(cd); + else if (ints & SI_TXPENDING) + // Schedule a transmit + report_line_txpending(cd); +} + + +/**************************************************************** + * Transmit queuing + ****************************************************************/ + +// API function to check if transmit space available +int +can2040_check_transmit(struct can2040 *cd) +{ + uint32_t tx_pull_pos = readl(&cd->tx_pull_pos); + uint32_t tx_push_pos = cd->tx_push_pos; + uint32_t pending = tx_push_pos - tx_pull_pos; + return pending < ARRAY_SIZE(cd->tx_queue); +} + +// API function to transmit a message +int +can2040_transmit(struct can2040 *cd, struct can2040_msg *msg) +{ + uint32_t tx_pull_pos = readl(&cd->tx_pull_pos); + uint32_t tx_push_pos = cd->tx_push_pos; + uint32_t pending = tx_push_pos - tx_pull_pos; + if (pending >= ARRAY_SIZE(cd->tx_queue)) + // Tx queue full + return -1; + + // Copy msg into transmit queue + struct can2040_transmit *qt = &cd->tx_queue[tx_qpos(cd, tx_push_pos)]; + uint32_t id = msg->id; + if (id & CAN2040_ID_EFF) + qt->msg.id = id & ~0x20000000; + else + qt->msg.id = id & (CAN2040_ID_RTR | 0x7ff); + qt->msg.dlc = msg->dlc & 0x0f; + uint32_t data_len = qt->msg.dlc > 8 ? 8 : qt->msg.dlc; + if (qt->msg.id & CAN2040_ID_RTR) + data_len = 0; + qt->msg.data32[0] = qt->msg.data32[1] = 0; + memcpy(qt->msg.data, msg->data, data_len); + + // Calculate crc and stuff bits + uint32_t crc = 0; + memset(qt->stuffed_data, 0, sizeof(qt->stuffed_data)); + struct bitstuffer_s bs = { 1, 0, qt->stuffed_data }; + uint32_t edlc = qt->msg.dlc | (qt->msg.id & CAN2040_ID_RTR ? 0x40 : 0); + if (qt->msg.id & CAN2040_ID_EFF) { + // Extended header + uint32_t id = qt->msg.id; + uint32_t h1 = ((id & 0x1ffc0000) >> 11) | 0x60 | ((id & 0x3e000) >> 13); + uint32_t h2 = ((id & 0x1fff) << 7) | edlc; + crc = crc_bytes(crc, h1 >> 4, 2); + crc = crc_bytes(crc, ((h1 & 0x0f) << 20) | h2, 3); + bs_push(&bs, h1, 19); + bs_push(&bs, h2, 20); + } else { + // Standard header + uint32_t hdr = ((qt->msg.id & 0x7ff) << 7) | edlc; + crc = crc_bytes(crc, hdr, 3); + bs_push(&bs, hdr, 19); + } + uint32_t i; + for (i=0; imsg.data[i]; + crc = crc_byte(crc, v); + bs_push(&bs, v, 8); + } + qt->crc = crc & 0x7fff; + bs_push(&bs, qt->crc, 15); + bs_pushraw(&bs, 1, 1); + qt->stuffed_words = bs_finalize(&bs); + + // Submit + writel(&cd->tx_push_pos, tx_push_pos + 1); + + // Wakeup if in TS_IDLE state + __DMB(); + pio_signal_set_txpending(cd); + + return 0; +} + + +/**************************************************************** + * Setup + ****************************************************************/ + +// API function to initialize can2040 code +void +can2040_setup(struct can2040 *cd, uint32_t pio_num) +{ + memset(cd, 0, sizeof(*cd)); + cd->pio_num = !!pio_num; + cd->pio_hw = cd->pio_num ? pio1_hw : pio0_hw; +} + +// API function to configure callback +void +can2040_callback_config(struct can2040 *cd, can2040_rx_cb rx_cb) +{ + cd->rx_cb = rx_cb; +} + +// API function to start CANbus interface +void +can2040_start(struct can2040 *cd, uint32_t sys_clock, uint32_t bitrate + , uint32_t gpio_rx, uint32_t gpio_tx) +{ + cd->gpio_rx = gpio_rx; + cd->gpio_tx = gpio_tx; + data_state_clear_bits(cd); + pio_setup(cd, sys_clock, bitrate); + data_state_go_discard(cd); +} + +// API function to stop can2040 code +void +can2040_stop(struct can2040 *cd) +{ + pio_irq_disable(cd); + pio_sm_setup(cd); +} + +// API function to access can2040 statistics +void +can2040_get_statistics(struct can2040 *cd, struct can2040_stats *stats) +{ + for (;;) { + memcpy(stats, &cd->stats, sizeof(*stats)); + if (memcmp(stats, &cd->stats, sizeof(*stats)) == 0) + // Successfully copied data + return; + // Raced with irq handler update - retry copy + } +} diff --git a/firmware/lib/can2040/src/can2040.h b/firmware/lib/can2040/src/can2040.h new file mode 100644 index 0000000..7dbee11 --- /dev/null +++ b/firmware/lib/can2040/src/can2040.h @@ -0,0 +1,86 @@ +#ifndef _CAN2040_H +#define _CAN2040_H + +#include // uint32_t + +struct can2040_msg { + uint32_t id; + uint32_t dlc; + union { + uint8_t data[8]; + uint32_t data32[2]; + }; +}; + +enum { + CAN2040_ID_RTR = 1<<30, + CAN2040_ID_EFF = 1<<31, +}; + +enum { + CAN2040_NOTIFY_RX = 1<<20, + CAN2040_NOTIFY_TX = 1<<21, + CAN2040_NOTIFY_ERROR = 1<<23, +}; +struct can2040; +typedef void (*can2040_rx_cb)(struct can2040 *cd, uint32_t notify + , struct can2040_msg *msg); + +struct can2040_stats { + uint32_t rx_total, tx_total; + uint32_t tx_attempt; + uint32_t parse_error; +}; + +void can2040_setup(struct can2040 *cd, uint32_t pio_num); +void can2040_callback_config(struct can2040 *cd, can2040_rx_cb rx_cb); +void can2040_start(struct can2040 *cd, uint32_t sys_clock, uint32_t bitrate + , uint32_t gpio_rx, uint32_t gpio_tx); +void can2040_stop(struct can2040 *cd); +void can2040_get_statistics(struct can2040 *cd, struct can2040_stats *stats); +void can2040_pio_irq_handler(struct can2040 *cd); +int can2040_check_transmit(struct can2040 *cd); +int can2040_transmit(struct can2040 *cd, struct can2040_msg *msg); + + +/**************************************************************** + * Internal definitions + ****************************************************************/ + +struct can2040_bitunstuffer { + uint32_t stuffed_bits, count_stuff; + uint32_t unstuffed_bits, count_unstuff; +}; + +struct can2040_transmit { + struct can2040_msg msg; + uint32_t crc, stuffed_words, stuffed_data[5]; +}; + +struct can2040 { + // Setup + uint32_t pio_num; + void *pio_hw; + uint32_t gpio_rx, gpio_tx; + can2040_rx_cb rx_cb; + struct can2040_stats stats; + + // Bit unstuffing + struct can2040_bitunstuffer unstuf; + uint32_t raw_bit_count; + + // Input data state + uint32_t parse_state; + uint32_t parse_crc, parse_crc_bits, parse_crc_pos; + struct can2040_msg parse_msg; + + // Reporting + uint32_t report_state; + + // Transmits + uint32_t tx_state; + uint32_t tx_pull_pos, tx_push_pos; + struct can2040_transmit tx_queue[4]; +}; + +#endif // can2040.h diff --git a/firmware/src/main.cpp b/firmware/src/main.cpp index 305396e..4aeaa64 100644 --- a/firmware/src/main.cpp +++ b/firmware/src/main.cpp @@ -4,6 +4,7 @@ #include "sd.h" #include "leds.h" #include "gfx_decoder.h" +#include "can2040.h" void loadVideo(size_t index);