diff options
| -rw-r--r-- | chip/stm32/spi.c | 56 |
1 files changed, 55 insertions, 1 deletions
diff --git a/chip/stm32/spi.c b/chip/stm32/spi.c index 960c6934b6..c6fd24bc36 100644 --- a/chip/stm32/spi.c +++ b/chip/stm32/spi.c @@ -89,6 +89,12 @@ static uint8_t enabled; static struct host_cmd_handler_args args; static struct host_packet spi_packet; +/* + * This is set if SPI NSS raises to high while EC is still processing a + * command. + */ +static int setup_transaction_later; + enum spi_state { /* SPI not enabled (initial state, and when chipset is off) */ SPI_STATE_DISABLED = 0, @@ -236,6 +242,9 @@ static void setup_for_transaction(void) stm32_spi_regs_t *spi = STM32_SPI1_REGS; volatile uint8_t dummy __attribute__((unused)); + /* clear this as soon as possible */ + setup_transaction_later = 0; + /* Not ready to receive yet */ spi->dr = EC_SPI_NOT_READY; @@ -259,6 +268,24 @@ static void setup_for_transaction(void) spi->dr = EC_SPI_OLD_READY; } + +/* + * If a setup_for_transaction() was postponed, call it now. + * Note that setup_for_transaction() cancels Tx DMA. + */ +static void check_setup_transaction_later(void) +{ + if (setup_transaction_later) { + setup_for_transaction(); + /* + * 'state' is set to SPI_STATE_READY_TO_RX. Somehow AP + * de-asserted the SPI NSS during the handler was running. + * Thus, the pending result will be dropped anyway. + */ + } +} + + /** * Called for V2 protocol to indicate that a command has completed * @@ -278,12 +305,21 @@ static void spi_send_response(struct host_cmd_handler_args *args) if (state != SPI_STATE_PROCESSING) return; + /* state == SPI_STATE_PROCESSING */ + if (args->response_size > args->response_max) result = EC_RES_INVALID_RESPONSE; /* Transmit the reply */ txdma = dma_get_channel(STM32_DMAC_SPI1_TX); reply(txdma, result, args->response, args->response_size); + + /* + * Before the state is set to SENDING, any CS de-assertion would + * set setup_transaction_later to 1. + */ + state = SPI_STATE_SENDING; + check_setup_transaction_later(); } /** @@ -304,6 +340,8 @@ static void spi_send_response_packet(struct host_packet *pkt) if (state != SPI_STATE_PROCESSING) return; + /* state == SPI_STATE_PROCESSING */ + /* Append our past-end byte, which we reserved space for. */ ((uint8_t *)pkt->response)[pkt->response_size] = EC_SPI_PAST_END; @@ -312,6 +350,13 @@ static void spi_send_response_packet(struct host_packet *pkt) dma_prepare_tx(&dma_tx_option, sizeof(out_preamble) + pkt->response_size + 1, out_msg); dma_go(txdma); + + /* + * Before the state is set to SENDING, any CS de-assertion would + * set setup_transaction_later to 1. + */ + state = SPI_STATE_SENDING; + check_setup_transaction_later(); } /** @@ -333,9 +378,18 @@ void spi_event(enum gpio_signal signal) if (!enabled) return; - /* Check chip select. If it's high, the AP ended a tranaction. */ + /* Check chip select. If it's high, the AP ended a transaction. */ nss_reg = gpio_get_level_reg(GPIO_SPI1_NSS, &nss_mask); if (REG16(nss_reg) & nss_mask) { + /* + * If the buffer is still used by the host command, postpone + * the DMA rx setup. + */ + if (state == SPI_STATE_PROCESSING) { + setup_transaction_later = 1; + return; + } + /* Set up for the next transaction */ setup_for_transaction(); return; |