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Diffstat (limited to 'src/atsamd/fdcan.c')
-rwxr-xr-xsrc/atsamd/fdcan.c293
1 files changed, 293 insertions, 0 deletions
diff --git a/src/atsamd/fdcan.c b/src/atsamd/fdcan.c
new file mode 100755
index 000000000..c12d91db8
--- /dev/null
+++ b/src/atsamd/fdcan.c
@@ -0,0 +1,293 @@
+// CANbus support on atsame51 chips
+//
+// Copyright (C) 2021-2022 Kevin O'Connor <kevin@koconnor.net>
+// Copyright (C) 2019 Eug Krashtan <eug.krashtan@gmail.com>
+// Copyright (C) 2020 Pontus Borg <glpontus@gmail.com>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include "command.h" // DECL_CONSTANT_STR
+#include "generic/armcm_boot.h" // armcm_enable_irq
+#include "generic/canbus.h" // canbus_notify_tx
+#include "generic/canserial.h" // CANBUS_ID_ADMIN
+#include "internal.h" // enable_pclock
+#include "sched.h" // DECL_INIT
+
+
+/****************************************************************
+ * Pin configuration
+ ****************************************************************/
+
+#if CONFIG_ATSAMD_CANBUS_PA23_PA22
+ DECL_CONSTANT_STR("RESERVE_PINS_CAN", "PA23,PA22");
+ #define GPIO_Rx GPIO('A', 23)
+ #define GPIO_Tx GPIO('A', 22)
+ #define CANx_GCLK_ID CAN0_GCLK_ID
+#elif CONFIG_ATSAMD_CANBUS_PA25_PA24
+ DECL_CONSTANT_STR("RESERVE_PINS_CAN", "PA25,PA24");
+ #define GPIO_Rx GPIO('A', 25)
+ #define GPIO_Tx GPIO('A', 24)
+ #define CANx_GCLK_ID CAN0_GCLK_ID
+#elif CONFIG_ATSAMD_CANBUS_PB13_PB12
+ DECL_CONSTANT_STR("RESERVE_PINS_CAN", "PB13,PB12");
+ #define GPIO_Rx GPIO('B', 13)
+ #define GPIO_Tx GPIO('B', 12)
+ #define CANx_GCLK_ID CAN1_GCLK_ID
+#elif CONFIG_ATSAMD_CANBUS_PB15_PB14
+ DECL_CONSTANT_STR("RESERVE_PINS_CAN", "PB15,PB14");
+ #define GPIO_Rx GPIO('B', 15)
+ #define GPIO_Tx GPIO('B', 14)
+ #define CANx_GCLK_ID CAN1_GCLK_ID
+#endif
+
+#if CANx_GCLK_ID == CAN0_GCLK_ID
+ #define CAN_FUNCTION 'I'
+ #define CANx CAN0
+ #define CANx_IRQn CAN0_IRQn
+#else
+ #define CAN_FUNCTION 'H'
+ #define CANx CAN1
+ #define CANx_IRQn CAN1_IRQn
+#endif
+
+
+/****************************************************************
+ * Message ram layout
+ ****************************************************************/
+
+struct fdcan_fifo {
+ uint32_t id_section;
+ uint32_t dlc_section;
+ uint32_t data[64 / 4];
+};
+
+#define FDCAN_XTD (1<<30)
+#define FDCAN_RTR (1<<29)
+
+struct fdcan_msg_ram {
+ uint32_t FLS[28]; // Filter list standard
+ uint32_t FLE[16]; // Filter list extended
+ struct fdcan_fifo RXF0[3];
+ struct fdcan_fifo RXF1[3];
+ uint32_t TEF[6]; // Tx event FIFO
+ struct fdcan_fifo TXFIFO[3];
+};
+
+// Message ram is in regular memory
+static struct fdcan_msg_ram MSG_RAM;
+
+
+/****************************************************************
+ * CANbus code
+ ****************************************************************/
+
+#define FDCAN_IE_TC (CAN_IE_TCE | CAN_IE_TCFE | CAN_IE_TFEE)
+
+// Transmit a packet
+int
+canbus_send(struct canbus_msg *msg)
+{
+ uint32_t txfqs = CANx->TXFQS.reg;
+ if (txfqs & CAN_TXFQS_TFQF)
+ // No space in transmit fifo - wait for irq
+ return -1;
+
+ uint32_t w_index = ((txfqs & CAN_TXFQS_TFQPI_Msk) >> CAN_TXFQS_TFQPI_Pos);
+ struct fdcan_fifo *txfifo = &MSG_RAM.TXFIFO[w_index];
+ uint32_t ids;
+ if (msg->id & CANMSG_ID_EFF)
+ ids = (msg->id & 0x1fffffff) | FDCAN_XTD;
+ else
+ ids = (msg->id & 0x7ff) << 18;
+ ids |= msg->id & CANMSG_ID_RTR ? FDCAN_RTR : 0;
+ txfifo->id_section = ids;
+ txfifo->dlc_section = (msg->dlc & 0x0f) << 16;
+ txfifo->data[0] = msg->data32[0];
+ txfifo->data[1] = msg->data32[1];
+ barrier();
+ CANx->TXBAR.reg = ((uint32_t)1 << w_index);
+ return CANMSG_DATA_LEN(msg);
+}
+
+static void
+can_filter(uint32_t index, uint32_t id)
+{
+ MSG_RAM.FLS[index] = ((0x2 << 30) // Classic filter
+ | (0x1 << 27) // Store in Rx FIFO 0 if filter matches
+ | (id << 16)
+ | 0x7FF); // mask all enabled
+}
+
+// Setup the receive packet filter
+void
+canbus_set_filter(uint32_t id)
+{
+ if (!CONFIG_CANBUS_FILTER)
+ return;
+ /* Request initialisation */
+ CANx->CCCR.reg |= CAN_CCCR_INIT;
+ /* Wait the acknowledge */
+ while (!(CANx->CCCR.reg & CAN_CCCR_INIT))
+ ;
+ /* Enable configuration change */
+ CANx->CCCR.reg |= CAN_CCCR_CCE;
+
+ // Load filter
+ can_filter(0, CANBUS_ID_ADMIN);
+ can_filter(1, id);
+ can_filter(2, id + 1);
+
+ uint32_t flssa = (uint32_t)MSG_RAM.FLS - CAN0_MSG_RAM_ADDR;
+ CANx->SIDFC.reg = flssa | ((id ? 3 : 1) << CAN_SIDFC_LSS_Pos);
+ CANx->GFC.reg = 0x02 << CAN_GFC_ANFS_Pos;
+
+ /* Leave the initialisation mode for the filter */
+ barrier();
+ CANx->CCCR.reg &= ~CAN_CCCR_CCE;
+ CANx->CCCR.reg &= ~CAN_CCCR_INIT;
+}
+
+// This function handles CAN global interrupts
+void
+CAN_IRQHandler(void)
+{
+ uint32_t ir = CANx->IR.reg;
+
+ if (ir & CAN_IE_RF0NE) {
+ CANx->IR.reg = CAN_IE_RF0NE;
+
+ uint32_t rxf0s = CANx->RXF0S.reg;
+ if (rxf0s & CAN_RXF0S_F0FL_Msk) {
+ // Read and ack data packet
+ uint32_t idx = (rxf0s & CAN_RXF0S_F0GI_Msk) >> CAN_RXF0S_F0GI_Pos;
+ struct fdcan_fifo *rxf0 = &MSG_RAM.RXF0[idx];
+ uint32_t ids = rxf0->id_section;
+ struct canbus_msg msg;
+ if (ids & FDCAN_XTD)
+ msg.id = (ids & 0x1fffffff) | CANMSG_ID_EFF;
+ else
+ msg.id = (ids >> 18) & 0x7ff;
+ msg.id |= ids & FDCAN_RTR ? CANMSG_ID_RTR : 0;
+ msg.dlc = (rxf0->dlc_section >> 16) & 0x0f;
+ msg.data32[0] = rxf0->data[0];
+ msg.data32[1] = rxf0->data[1];
+ barrier();
+ CANx->RXF0A.reg = idx;
+
+ // Process packet
+ canbus_process_data(&msg);
+ }
+ }
+ if (ir & FDCAN_IE_TC) {
+ // Tx
+ CANx->IR.reg = FDCAN_IE_TC;
+ canbus_notify_tx();
+ }
+}
+
+static inline const uint32_t
+make_btr(uint32_t sjw, // Sync jump width, ... hmm
+ uint32_t time_seg1, // time segment before sample point, 1 .. 16
+ uint32_t time_seg2, // time segment after sample point, 1 .. 8
+ uint32_t brp) // Baud rate prescaler, 1 .. 1024
+{
+ return (((uint32_t)(sjw-1)) << CAN_NBTP_NSJW_Pos
+ | ((uint32_t)(time_seg1-1)) << CAN_NBTP_NTSEG1_Pos
+ | ((uint32_t)(time_seg2-1)) << CAN_NBTP_NTSEG2_Pos
+ | ((uint32_t)(brp - 1)) << CAN_NBTP_NBRP_Pos);
+}
+
+static inline const uint32_t
+compute_btr(uint32_t pclock, uint32_t bitrate)
+{
+ /*
+ Some equations:
+ Tpclock = 1 / pclock
+ Tq = brp * Tpclock
+ Tbs1 = Tq * TS1
+ Tbs2 = Tq * TS2
+ NominalBitTime = Tq + Tbs1 + Tbs2
+ BaudRate = 1/NominalBitTime
+ Bit value sample point is after Tq+Tbs1. Ideal sample point
+ is at 87.5% of NominalBitTime
+ Use the lowest brp where ts1 and ts2 are in valid range
+ */
+
+ uint32_t bit_clocks = pclock / bitrate; // clock ticks per bit
+
+ uint32_t sjw = 2;
+ uint32_t qs;
+ // Find number of time quantas that gives us the exact wanted bit time
+ for (qs = 18; qs > 9; qs--) {
+ // check that bit_clocks / quantas is an integer
+ uint32_t brp_rem = bit_clocks % qs;
+ if (brp_rem == 0)
+ break;
+ }
+ uint32_t brp = bit_clocks / qs;
+ uint32_t time_seg2 = qs / 8; // sample at ~87.5%
+ uint32_t time_seg1 = qs - (1 + time_seg2);
+
+ return make_btr(sjw, time_seg1, time_seg2, brp);
+}
+
+void
+can_init(void)
+{
+ if (!CONFIG_USB) {
+ // The FDCAN peripheral only seems to run if at least one
+ // other peripheral is also enabled.
+ enable_pclock(USB_GCLK_ID, ID_USB);
+ USB->DEVICE.CTRLA.reg = USB_CTRLA_ENABLE;
+ }
+
+ enable_pclock(CANx_GCLK_ID, -1);
+
+ gpio_peripheral(GPIO_Rx, CAN_FUNCTION, 1);
+ gpio_peripheral(GPIO_Tx, CAN_FUNCTION, 0);
+
+ uint32_t pclock = get_pclock_frequency(CANx_GCLK_ID);
+
+ uint32_t btr = compute_btr(pclock, CONFIG_CANBUS_FREQUENCY);
+
+ /*##-1- Configure the CAN #######################################*/
+
+ /* Exit from sleep mode */
+ CANx->CCCR.reg &= ~CAN_CCCR_CSR;
+ /* Wait the acknowledge */
+ while (CANx->CCCR.reg & CAN_CCCR_CSA)
+ ;
+ /* Request initialisation */
+ CANx->CCCR.reg |= CAN_CCCR_INIT;
+ /* Wait the acknowledge */
+ while (!(CANx->CCCR.reg & CAN_CCCR_INIT))
+ ;
+ /* Enable configuration change */
+ CANx->CCCR.reg |= CAN_CCCR_CCE;
+
+ /* Disable protocol exception handling */
+ CANx->CCCR.reg |= CAN_CCCR_PXHD;
+
+ CANx->NBTP.reg = btr;
+
+ /* Setup message RAM addresses */
+ uint32_t f0sa = (uint32_t)MSG_RAM.RXF0 - CAN0_MSG_RAM_ADDR;
+ CANx->RXF0C.reg = f0sa | (ARRAY_SIZE(MSG_RAM.RXF0) << CAN_RXF0C_F0S_Pos);
+ CANx->RXESC.reg = (7 << CAN_RXESC_F1DS_Pos) | (7 << CAN_RXESC_F0DS_Pos);
+ uint32_t tbsa = (uint32_t)MSG_RAM.TXFIFO - CAN0_MSG_RAM_ADDR;
+ CANx->TXBC.reg = tbsa | (ARRAY_SIZE(MSG_RAM.TXFIFO) << CAN_TXBC_TFQS_Pos);
+ CANx->TXESC.reg = 7 << CAN_TXESC_TBDS_Pos;
+
+ /* Leave the initialisation mode */
+ CANx->CCCR.reg &= ~CAN_CCCR_CCE;
+ CANx->CCCR.reg &= ~CAN_CCCR_INIT;
+
+ /*##-2- Configure the CAN Filter #######################################*/
+ canbus_set_filter(0);
+
+ /*##-3- Configure Interrupts #################################*/
+ armcm_enable_irq(CAN_IRQHandler, CANx_IRQn, 1);
+ CANx->ILE.reg = CAN_ILE_EINT0;
+ CANx->IE.reg = CAN_IE_RF0NE | FDCAN_IE_TC;
+}
+DECL_INIT(can_init);
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