diff options
author | Kévin Redon <kredon@sysmocom.de> | 2020-03-26 01:46:45 +0100 |
---|---|---|
committer | Harald Welte <laforge@osmocom.org> | 2021-04-04 23:01:41 +0200 |
commit | b218cc38d0dc85c6ab8efa616d0e1a73ee36b9e2 (patch) | |
tree | 9e7b1d5cdb8576ba8f0d19d489c5fa1dd3f66aa7 | |
parent | 50360e0706e8d5ee7b9934b72168691a7bb43c33 (diff) |
minor add comments
this is just to better understand the flow
Change-Id: I045286836176da729cc8c863866d6f6aa3836592
-rw-r--r-- | firmware/libcommon/source/mode_cardemu.c | 36 |
1 files changed, 28 insertions, 8 deletions
diff --git a/firmware/libcommon/source/mode_cardemu.c b/firmware/libcommon/source/mode_cardemu.c index 6a8d98f..4886983 100644 --- a/firmware/libcommon/source/mode_cardemu.c +++ b/firmware/libcommon/source/mode_cardemu.c @@ -1,7 +1,7 @@ /* card emulation mode * * (C) 2015-2017 by Harald Welte <laforge@gnumonks.org> - * (C) 2018 by sysmocom -s.f.m.c. GmbH, Author: Kevin Redon <kredon@sysmocom.de> + * (C) 2018-2019 by sysmocom -s.f.m.c. GmbH, Author: Kevin Redon <kredon@sysmocom.de> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -194,7 +194,8 @@ int card_emu_uart_tx(uint8_t uart_chan, uint8_t byte) } -/* FIXME: integrate this with actual irq handler */ +/*! common handler if interrupt was received. + * \param[in] inst_num Instance number, range 0..1 (some boards only '0' permitted) */ static void usart_irq_rx(uint8_t inst_num) { Usart *usart = get_usart_by_chan(inst_num); @@ -202,32 +203,43 @@ static void usart_irq_rx(uint8_t inst_num) uint32_t csr; uint8_t byte = 0; + /* get one atomic snapshot of state/flags before they get changed */ csr = usart->US_CSR & usart->US_IMR; + /* check if one byte has been completely received and is now in the holding register */ if (csr & US_CSR_RXRDY) { + /* read the bye from the holding register */ byte = (usart->US_RHR) & 0xFF; + /* append it to the buffer */ if (rbuf_write(&ci->rb, byte) < 0) TRACE_ERROR("rbuf overrun\r\n"); } + /* check if the transmitter is ready for the next byte */ if (csr & US_CSR_TXRDY) { - if (card_emu_tx_byte(ci->ch) == 0) + /* transmit next byte and check if more bytes are to be transmitted */ + if (card_emu_tx_byte(ci->ch) == 0) { + /* stop the TX ready interrupt of no more bytes to transmit */ USART_DisableIt(usart, US_IER_TXRDY); + } } - if (csr & (US_CSR_OVRE|US_CSR_FRAME|US_CSR_PARE| - US_CSR_TIMEOUT|US_CSR_NACK|(1<<10))) { + /* check if any error flags are set */ + if (csr & (US_CSR_OVRE|US_CSR_FRAME|US_CSR_PARE|US_CSR_TIMEOUT|US_CSR_NACK|(1<<10))) { + /* clear any error flags */ usart->US_CR = US_CR_RSTSTA | US_CR_RSTIT | US_CR_RSTNACK; - TRACE_ERROR("%u e 0x%x st: 0x%lx\n", ci->num, byte, csr); + TRACE_ERROR("%u USART error on 0x%x status: 0x%lx\n", ci->num, byte, csr); } } +/*! ISR called for USART0 */ void mode_cardemu_usart0_irq(void) { /* USART0 == Instance 1 == USIM 2 */ usart_irq_rx(1); } +/*! ISR called for USART1 */ void mode_cardemu_usart1_irq(void) { /* USART1 == Instance 0 == USIM 1 */ @@ -419,15 +431,21 @@ void mode_cardemu_init(void) INIT_LLIST_HEAD(&cardem_inst[0].usb_out_queue); rbuf_reset(&cardem_inst[0].rb); PIO_Configure(pins_usim1, PIO_LISTSIZE(pins_usim1)); + + /* configure USART as ISO-7816 slave (e.g. card) */ ISO7816_Init(&cardem_inst[0].usart_info, CLK_SLAVE); NVIC_EnableIRQ(USART1_IRQn); PIO_ConfigureIt(&pin_usim1_rst, usim1_rst_irqhandler); PIO_EnableIt(&pin_usim1_rst); - usim1_rst_irqhandler(&pin_usim1_rst); /* obtain current RST state */ + + /* obtain current RST state */ + usim1_rst_irqhandler(&pin_usim1_rst); #ifndef DETECT_VCC_BY_ADC PIO_ConfigureIt(&pin_usim1_vcc, usim1_vcc_irqhandler); PIO_EnableIt(&pin_usim1_vcc); - usim1_vcc_irqhandler(&pin_usim1_vcc); /* obtain current VCC state */ + + /* obtain current VCC state */ + usim1_vcc_irqhandler(&pin_usim1_vcc); #else do {} while (!adc_triggered); /* wait for first ADC reading */ #endif /* DETECT_VCC_BY_ADC */ @@ -442,6 +460,7 @@ void mode_cardemu_init(void) rbuf_reset(&cardem_inst[1].rb); PIO_Configure(pins_usim2, PIO_LISTSIZE(pins_usim2)); ISO7816_Init(&cardem_inst[1].usart_info, CLK_SLAVE); + /* TODO enable timeout */ NVIC_EnableIRQ(USART0_IRQn); PIO_ConfigureIt(&pin_usim2_rst, usim2_rst_irqhandler); PIO_EnableIt(&pin_usim2_rst); @@ -458,6 +477,7 @@ void mode_cardemu_init(void) SIMTRACE_CARDEM_USB_EP_USIM2_INT, cardem_inst[1].vcc_active, cardem_inst[1].rst_active, cardem_inst[1].vcc_active); sim_switch_use_physical(1, 1); + /* TODO check RST and VCC */ #endif /* CARDEMU_SECOND_UART */ } |