From f87eb70c6a881e6656693ab7edd9984afaf98b42 Mon Sep 17 00:00:00 2001 From: DrDoof <8052722+DrDoof@users.noreply.github.com> Date: Wed, 23 Sep 2026 16:04:23 +0200 Subject: [PATCH] rtlplayground: read the link registers when the switch reports a change The link-change interrupt was set up at boot (mode 0x5f84, mask 0x5f34) but never enabled: the handler did nothing and did not clear the event in the switch, so EX0 stayed commented out and idle() read the two link registers on every pass instead, 400 reads a second on a quiet switch. The handler now only latches a flag and masks itself; the register access macros build a write in the shared SFR data bytes, so an interrupt that touched the switch in the middle of a write from the main loop would corrupt it. idle() clears the event register (write-one-to-clear, 0x3ff for the ten ports), re-enables EX0 and then reads the link state, in that order, so a change that lands during the read raises a new edge. The flag is also set once a second from the seconds block, so a board whose INT0 line turns out not to be wired keeps detecting link changes, a second late at worst. Boot drops the events pending from bringing the links up before the mask is set. Measured on an RTL8373 switch before this change: 0x5f88 held 0x3fd, nine ports had reported a change nobody read. With the change a counter in the loop went 2 -> 3 -> 4 on "port 5 off" / "port 5 on" and stayed at 4 over three reads without events, so the event is delivered, cleared and re-armed, and there is no flood. SWTGW218AS: code +57 B, xdata 0, stack 151 -> 150 B; the flag is a bit variable. The handler compiles to clr EX0 / setb link_irq / reti. idle() also keeps in a bit what it saw in NIC_RX_BUFF_DATA when deciding whether to sleep, and the first iteration of the receive loop uses it instead of reading the register again a moment later. Between the two only the link check and handle_sfp() run, and neither can make a queued packet disappear. Every later iteration reads the register as before, so the budget loop behaves as it did. This part was not measured on hardware: one register read per pass needs a throughput run to show up. SWTGW218AS: BANK1 and BANK2 +6 bytes each, BANK3 unchanged. --- rtl837x_regs.h | 3 + rtlplayground.c | 148 +++++++++++++++++++++++++++--------------------- 2 files changed, 87 insertions(+), 64 deletions(-) diff --git a/rtl837x_regs.h b/rtl837x_regs.h index 8d85accd..6409043d 100644 --- a/rtl837x_regs.h +++ b/rtl837x_regs.h @@ -274,6 +274,9 @@ */ #define RTL8373_RLDP_TIMER 0x1074 #define RTL837X_RMA0_CONF 0x4ecc +#define RTL837X_IMR_INT_PORT_LINK_STS_CHG 0x5f34 +#define RTL837X_ISR_SW_INT_MODE 0x5f84 +#define RTL837X_ISR_INT_PORT_LINK_CHG 0x5f88 #define RTL837X_RMA_CONF 0x4f1c #define RTL837X_MSTP_STATES 0x5310 #define RTL837X_REG_LED_RLDP_1 0x65F8 diff --git a/rtlplayground.c b/rtlplayground.c index cd1281f7..0208f844 100644 --- a/rtlplayground.c +++ b/rtlplayground.c @@ -136,10 +136,12 @@ __code const uint16_t bit_mask[16] = { __xdata uint8_t linkbits_last[4]; __xdata uint8_t linkbits_last_p89; +volatile __bit link_irq; // Last known state of the SFP detection/Loss of Signal pins __xdata bool button_last; __xdata uint8_t button_sec_counter_last; volatile __bit tx_buf_empty; +__bit rx_seen; struct eth_in { @@ -491,14 +493,14 @@ void print_cmd_prompt(void) } /* - * External IRQ 0 Service Routine: Called on link change? - * Note that all registers are being put on the STACK because of calling a subroutine + * External IRQ 0 Service Routine: the switch reports a link change. The + * register access macros share the SFR data bytes with the main loop, so + * the handler only latches the event; idle() reads and clears it. */ void isr_ext0(void) __interrupt(0) { - EX0 = 0; // Disable interrupt for the moment - IT0 = 1; // Trigger on falling edge of external interrupt - EX0 = 1; // Re-enable interrupt + EX0 = 0; + link_irq = 1; } @@ -993,10 +995,14 @@ void handle_rx(void) __xdata uint8_t budget = RX_BUDGET; while (budget--) { - // Check the amount of data available on the NIC/ASIC side - reg_read(RTL837X_REG_NIC_RX_BUFF_DATA); - if (!SFR_DATA_U16) - break; + if (rx_seen) { + rx_seen = 0; + } else { + // Check the amount of data available on the NIC/ASIC side + reg_read(RTL837X_REG_NIC_RX_BUFF_DATA); + if (!SFR_DATA_U16) + break; + } reg_read(RTL837X_REG_CPU_RX_CURR_PKT); uint16_t ring_ptr = SFR_DATA_U16; ring_ptr <<= 3; @@ -1174,57 +1180,8 @@ void handle_button(void) } } -// -// An idle function that sleeps for 1 tick and does all the house-keeping -// -void idle(void) +void check_links(void) { - reg_read(RTL837X_REG_NIC_RX_BUFF_DATA); - if (!SFR_DATA_U16) - PCON |= 1; - health_loop_start(); - if (sec_counter >= SYS_TICK_HZ) { - sec_counter -= SYS_TICK_HZ; - reg_read_m(RTL837X_REG_SEC_COUNTER); - uint8_t v = sfr_data[3]; -#ifdef DEBUG - print_string(" Tick counter: "); print_long(ticks); write_char('\n'); -#endif - v++; - sfr_data[3] = v; - if (!v) { - v = sfr_data[2]; - v++; - sfr_data[2] = v; - if (!v) { - v = sfr_data[1]; - v++; - sfr_data[1] = v; - if (!v) { - v = sfr_data[0]; - v++; - sfr_data[0] = v; - } - } - } - reg_write_m(RTL837X_REG_SEC_COUNTER); - reg_read_m(RTL837X_REG_SEC_COUNTER); - - // Check for button presses once a second - handle_button(); - // Age the ARP cache: uip_arp_timer() expects a 10 s cadence - if (++arp_age_secs >= 10) { - arp_age_secs = 0; - uip_arp_timer(); - } - -#ifdef DEBUG - print_sfr_data(); - write_char('\n'); -#endif - } - - // Check for Link changes reg_read_m(RTL837X_REG_LINKS_89); __xdata uint8_t linkbits_p89 = sfr_data[3]; @@ -1257,6 +1214,68 @@ void idle(void) cpy_4(linkbits_last, sfr_data); } } +} + + +// +// An idle function that sleeps for 1 tick and does all the house-keeping +// +void idle(void) +{ + reg_read(RTL837X_REG_NIC_RX_BUFF_DATA); + rx_seen = SFR_DATA_U16 != 0; + if (!rx_seen) + PCON |= 1; + health_loop_start(); + if (sec_counter >= SYS_TICK_HZ) { + sec_counter -= SYS_TICK_HZ; + reg_read_m(RTL837X_REG_SEC_COUNTER); + uint8_t v = sfr_data[3]; +#ifdef DEBUG + print_string(" Tick counter: "); print_long(ticks); write_char('\n'); +#endif + v++; + sfr_data[3] = v; + if (!v) { + v = sfr_data[2]; + v++; + sfr_data[2] = v; + if (!v) { + v = sfr_data[1]; + v++; + sfr_data[1] = v; + if (!v) { + v = sfr_data[0]; + v++; + sfr_data[0] = v; + } + } + } + reg_write_m(RTL837X_REG_SEC_COUNTER); + reg_read_m(RTL837X_REG_SEC_COUNTER); + + // Check for button presses once a second + handle_button(); + link_irq = 1; + // Age the ARP cache: uip_arp_timer() expects a 10 s cadence + if (++arp_age_secs >= 10) { + arp_age_secs = 0; + uip_arp_timer(); + } + +#ifdef DEBUG + print_sfr_data(); + write_char('\n'); +#endif + } + + // Check for Link changes when the switch has reported one + if (link_irq) { + link_irq = 0; + REG_SET(RTL837X_ISR_INT_PORT_LINK_CHG, 0x3ff); + EX0 = 1; + check_links(); + } health_phase(HEALTH_PH_LINK); @@ -1313,12 +1332,13 @@ void reset_chip(void) void setup_external_irqs(void) { - REG_SET(0x5f84, 0x42); - REG_SET(0x5f34, 0x3ff); + REG_SET(RTL837X_ISR_SW_INT_MODE, 0x42); + REG_SET(RTL837X_ISR_INT_PORT_LINK_CHG, 0x3ff); + REG_SET(RTL837X_IMR_INT_PORT_LINK_STS_CHG, 0x3ff); -// EX0 = 1; // Enable external IRQ 0 (Link-change) - EX0 = 0; - IT0 = 1; // External IRQ on falling edge + link_irq = 1; + IT0 = 1; // External IRQ 0 on falling edge (link change) + EX0 = 1; EX1 = 1; // External IRQ 1 enable EX2 = 1; // External IRQ 2 enable: bit EIE.0