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drivers: CAN: MCP2515: Add and use RTS instruction

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Reduces SPI data required for Request To Send from 4 bytes to 1

Signed-off-by: Nick Ward <nix.ward@gmail.com>
This commit is contained in:
Nick Ward 2019-08-08 00:23:34 +10:00 • committed by Jukka Rissanen
commit d5a5d960e6
2 changed files with 27 additions and 6 deletions
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32
drivers/can/can_mcp2515.c
View file

@ -92,6 +92,29 @@ static int mcp2515_cmd_load_tx_buffer(struct device *dev, u8_t abc,
return spi_write(DEV_DATA(dev)->spi, &DEV_DATA(dev)->spi_cfg, &tx);
}
/*
* Request-to-Send Instruction
*
* Parameter nnn is the combination of bits at positions 0, 1 and 2 in the RTS
* opcode that respectively initiate transmission for buffers TXB0, TXB1 and
* TXB2.
*/
static int mcp2515_cmd_rts(struct device *dev, u8_t nnn)
{
__ASSERT(nnn < BIT(MCP2515_TX_CNT), "nnn < BIT(MCP2515_TX_CNT)");
u8_t cmd_buf[] = { MCP2515_OPCODE_RTS | nnn };
struct spi_buf tx_buf[] = {
{ .buf = cmd_buf, .len = sizeof(cmd_buf) }
};
const struct spi_buf_set tx = {
.buffers = tx_buf, .count = ARRAY_SIZE(tx_buf)
};
return spi_write(DEV_DATA(dev)->spi, &DEV_DATA(dev)->spi_cfg, &tx);
}
static int mcp2515_cmd_read_reg(struct device *dev, u8_t reg_addr,
u8_t *buf_data, u8_t buf_len)
{
@ -325,7 +348,7 @@ static int mcp2515_send(struct device *dev, const struct zcan_frame *msg,
struct mcp2515_data *dev_data = DEV_DATA(dev);
u8_t tx_idx = 0U;
u8_t abc;
u8_t addr_tx_ctrl;
u8_t nnn;
u8_t tx_frame[MCP2515_FRAME_LEN];
if (k_sem_take(&dev_data->tx_sem, timeout) != 0) {
@ -352,9 +375,6 @@ static int mcp2515_send(struct device *dev, const struct zcan_frame *msg,
dev_data->tx_cb[tx_idx].cb = callback;
dev_data->tx_cb[tx_idx].cb_arg = callback_arg;
addr_tx_ctrl = MCP2515_ADDR_TXB0CTRL +
(tx_idx * MCP2515_ADDR_OFFSET_FRAME2FRAME);
mcp2515_convert_zcanframe_to_mcp2515frame(msg, tx_frame);
/* Address Pointer selection */
@ -363,8 +383,8 @@ static int mcp2515_send(struct device *dev, const struct zcan_frame *msg,
mcp2515_cmd_load_tx_buffer(dev, abc, tx_frame, sizeof(tx_frame));
/* request tx slot transmission */
mcp2515_cmd_bit_modify(dev, addr_tx_ctrl, MCP2515_TXCTRL_TXREQ,
MCP2515_TXCTRL_TXREQ);
nnn = BIT(tx_idx);
mcp2515_cmd_rts(dev, nnn);
if (callback == NULL) {
k_sem_take(&dev_data->tx_cb[tx_idx].sem, K_FOREVER);

1
drivers/can/can_mcp2515.h
View file

@ -83,6 +83,7 @@ struct mcp2515_config {
#define MCP2515_OPCODE_READ 0x03
#define MCP2515_OPCODE_BIT_MODIFY 0x05
#define MCP2515_OPCODE_LOAD_TX_BUFFER 0x40
#define MCP2515_OPCODE_RTS 0x80
#define MCP2515_OPCODE_READ_STATUS 0xA0
#define MCP2515_OPCODE_RESET 0xC0