diff options
| -rw-r--r-- | hw/char/pl011.c | 110 |
1 files changed, 108 insertions, 2 deletions
diff --git a/hw/char/pl011.c b/hw/char/pl011.c index 855cb82d08..8753b84a84 100644 --- a/hw/char/pl011.c +++ b/hw/char/pl011.c @@ -49,10 +49,14 @@ DeviceState *pl011_create(hwaddr addr, qemu_irq irq, Chardev *chr) } /* Flag Register, UARTFR */ +#define PL011_FLAG_RI 0x100 #define PL011_FLAG_TXFE 0x80 #define PL011_FLAG_RXFF 0x40 #define PL011_FLAG_TXFF 0x20 #define PL011_FLAG_RXFE 0x10 +#define PL011_FLAG_DCD 0x04 +#define PL011_FLAG_DSR 0x02 +#define PL011_FLAG_CTS 0x01 /* Data Register, UARTDR */ #define DR_BE (1 << 10) @@ -76,6 +80,13 @@ DeviceState *pl011_create(hwaddr addr, qemu_irq irq, Chardev *chr) #define LCR_FEN (1 << 4) #define LCR_BRK (1 << 0) +/* Control Register, UARTCR */ +#define CR_OUT2 (1 << 13) +#define CR_OUT1 (1 << 12) +#define CR_RTS (1 << 11) +#define CR_DTR (1 << 10) +#define CR_LBE (1 << 7) + static const unsigned char pl011_id_arm[8] = { 0x11, 0x10, 0x14, 0x00, 0x0d, 0xf0, 0x05, 0xb1 }; static const unsigned char pl011_id_luminary[8] = @@ -251,6 +262,89 @@ static void pl011_trace_baudrate_change(const PL011State *s) s->ibrd, s->fbrd); } +static bool pl011_loopback_enabled(PL011State *s) +{ + return !!(s->cr & CR_LBE); +} + +static void pl011_loopback_mdmctrl(PL011State *s) +{ + uint32_t cr, fr, il; + + if (!pl011_loopback_enabled(s)) { + return; + } + + /* + * Loopback software-driven modem control outputs to modem status inputs: + * FR.RI <= CR.Out2 + * FR.DCD <= CR.Out1 + * FR.CTS <= CR.RTS + * FR.DSR <= CR.DTR + * + * The loopback happens immediately even if this call is triggered + * by setting only CR.LBE. + * + * CTS/RTS updates due to enabled hardware flow controls are not + * dealt with here. + */ + cr = s->cr; + fr = s->flags & ~(PL011_FLAG_RI | PL011_FLAG_DCD | + PL011_FLAG_DSR | PL011_FLAG_CTS); + fr |= (cr & CR_OUT2) ? PL011_FLAG_RI : 0; + fr |= (cr & CR_OUT1) ? PL011_FLAG_DCD : 0; + fr |= (cr & CR_RTS) ? PL011_FLAG_CTS : 0; + fr |= (cr & CR_DTR) ? PL011_FLAG_DSR : 0; + + /* Change interrupts based on updated FR */ + il = s->int_level & ~(INT_DSR | INT_DCD | INT_CTS | INT_RI); + il |= (fr & PL011_FLAG_DSR) ? INT_DSR : 0; + il |= (fr & PL011_FLAG_DCD) ? INT_DCD : 0; + il |= (fr & PL011_FLAG_CTS) ? INT_CTS : 0; + il |= (fr & PL011_FLAG_RI) ? INT_RI : 0; + + s->flags = fr; + s->int_level = il; + pl011_update(s); +} + +static void pl011_put_fifo(void *opaque, uint32_t value); + +static void pl011_loopback_tx(PL011State *s, uint32_t value) +{ + if (!pl011_loopback_enabled(s)) { + return; + } + + /* + * Caveat: + * + * In real hardware, TX loopback happens at the serial-bit level + * and then reassembled by the RX logics back into bytes and placed + * into the RX fifo. That is, loopback happens after TX fifo. + * + * Because the real hardware TX fifo is time-drained at the frame + * rate governed by the configured serial format, some loopback + * bytes in TX fifo may still be able to get into the RX fifo + * that could be full at times while being drained at software + * pace. + * + * In such scenario, the RX draining pace is the major factor + * deciding which loopback bytes get into the RX fifo, unless + * hardware flow-control is enabled. + * + * For simplicity, the above described is not emulated. + */ + pl011_put_fifo(s, value); +} + +static void pl011_loopback_break(PL011State *s, int brk_enable) +{ + if (brk_enable) { + pl011_loopback_tx(s, DR_BE); + } +} + static void pl011_write(void *opaque, hwaddr offset, uint64_t value, unsigned size) { @@ -266,6 +360,7 @@ static void pl011_write(void *opaque, hwaddr offset, /* XXX this blocks entire thread. Rewrite to use * qemu_chr_fe_write and background I/O callbacks */ qemu_chr_fe_write_all(&s->chr, &ch, 1); + pl011_loopback_tx(s, ch); s->int_level |= INT_TX; pl011_update(s); break; @@ -295,13 +390,15 @@ static void pl011_write(void *opaque, hwaddr offset, int break_enable = value & LCR_BRK; qemu_chr_fe_ioctl(&s->chr, CHR_IOCTL_SERIAL_SET_BREAK, &break_enable); + pl011_loopback_break(s, break_enable); } s->lcr = value; pl011_set_read_trigger(s); break; case 12: /* UARTCR */ - /* ??? Need to implement the enable and loopback bits. */ + /* ??? Need to implement the enable bit. */ s->cr = value; + pl011_loopback_mdmctrl(s); break; case 13: /* UARTIFS */ s->ifl = value; @@ -361,12 +458,21 @@ static void pl011_put_fifo(void *opaque, uint32_t value) static void pl011_receive(void *opaque, const uint8_t *buf, int size) { + /* + * In loopback mode, the RX input signal is internally disconnected + * from the entire receiving logics; thus, all inputs are ignored, + * and BREAK detection on RX input signal is also not performed. + */ + if (pl011_loopback_enabled(opaque)) { + return; + } + pl011_put_fifo(opaque, *buf); } static void pl011_event(void *opaque, QEMUChrEvent event) { - if (event == CHR_EVENT_BREAK) { + if (event == CHR_EVENT_BREAK && !pl011_loopback_enabled(opaque)) { pl011_put_fifo(opaque, DR_BE); } } |