On Thu, 27 Aug 2025, dmuk...@xen.org wrote: > From: Denis Mukhin <dmuk...@ford.com> > > Added missing definitions needed for NS16550 UART emulator. > > Newly introduced MSR definitions re-used in the existing ns16550 driver. > > Also, corrected FCR DMA definition bit#3 (0x08) as per: > https://www.ti.com/lit/ds/symlink/tl16c550c.pdf > See "7.7.2 FIFO Control Register (FCR)". > > Signed-off-by: Denis Mukhin <dmuk...@ford.com> > --- > Changes since v4: > - reused newly introduced UART_IIR and UART_IER bits in ns16550 driver > - Link to v4: > https://lore.kernel.org/xen-devel/20250731192130.3948419-5-dmuk...@ford.com/ > --- > xen/drivers/char/ns16550.c | 16 ++++++------ > xen/include/xen/8250-uart.h | 50 ++++++++++++++++++++++++++++++------- > 2 files changed, 49 insertions(+), 17 deletions(-) > > diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c > index df7fff7f81df..0e80fadbb894 100644 > --- a/xen/drivers/char/ns16550.c > +++ b/xen/drivers/char/ns16550.c > @@ -388,7 +388,7 @@ static void __init cf_check ns16550_init_preirq(struct > serial_port *port) > > /* Check this really is a 16550+. Otherwise we have no FIFOs. */ > if ( uart->fifo_size <= 1 && > - ((ns_read_reg(uart, UART_IIR) & 0xc0) == 0xc0) && > + ((ns_read_reg(uart, UART_IIR) & UART_IIR_FE) == UART_IIR_FE) && > ((ns_read_reg(uart, UART_FCR) & UART_FCR_TRG14) == UART_FCR_TRG14) ) > uart->fifo_size = 16; > } > @@ -728,20 +728,20 @@ static int __init check_existence(struct ns16550 *uart) > * Mask out IER[7:4] bits for test as some UARTs (e.g. TL > * 16C754B) allow only to modify them if an EFR bit is set. > */ > - scratch2 = ns_read_reg(uart, UART_IER) & 0x0f; > - ns_write_reg(uart,UART_IER, 0x0F); > - scratch3 = ns_read_reg(uart, UART_IER) & 0x0f; > + scratch2 = ns_read_reg(uart, UART_IER) & UART_IER_MASK; > + ns_write_reg(uart, UART_IER, UART_IER_MASK); > + scratch3 = ns_read_reg(uart, UART_IER) & UART_IER_MASK; > ns_write_reg(uart, UART_IER, scratch); > - if ( (scratch2 != 0) || (scratch3 != 0x0F) ) > + if ( (scratch2 != 0) || (scratch3 != UART_IER_MASK) ) > return 0; > > /* > * Check to see if a UART is really there. > * Use loopback test mode. > */ > - ns_write_reg(uart, UART_MCR, UART_MCR_LOOP | 0x0A); > - status = ns_read_reg(uart, UART_MSR) & 0xF0; > - return (status == 0x90); > + ns_write_reg(uart, UART_MCR, UART_MCR_LOOP | UART_MCR_RTS | > UART_MCR_OUT2); > + status = ns_read_reg(uart, UART_MSR) & UART_MSR_STATUS; > + return (status == (UART_MSR_CTS | UART_MSR_DCD)); > } > > #ifdef CONFIG_HAS_PCI > diff --git a/xen/include/xen/8250-uart.h b/xen/include/xen/8250-uart.h > index d13352940c13..bc11cdc376c9 100644 > --- a/xen/include/xen/8250-uart.h > +++ b/xen/include/xen/8250-uart.h > @@ -32,6 +32,7 @@ > #define UART_MCR 0x04 /* Modem control */ > #define UART_LSR 0x05 /* line status */ > #define UART_MSR 0x06 /* Modem status */ > +#define UART_SCR 0x07 /* Scratch pad */ > #define UART_USR 0x1f /* Status register (DW) */ > #define UART_DLL 0x00 /* divisor latch (ls) (DLAB=1) */ > #define UART_DLM 0x01 /* divisor latch (ms) (DLAB=1) */ > @@ -42,6 +43,8 @@ > #define UART_IER_ETHREI 0x02 /* tx reg. empty */ > #define UART_IER_ELSI 0x04 /* rx line status */ > #define UART_IER_EMSI 0x08 /* MODEM status */ > +#define UART_IER_MASK \ > + (UART_IER_ERDAI | UART_IER_ETHREI | UART_IER_ELSI | UART_IER_EMSI) > > /* Interrupt Identification Register */ > #define UART_IIR_NOINT 0x01 /* no interrupt pending */ > @@ -51,12 +54,19 @@ > #define UART_IIR_THR 0x02 /* - tx reg. empty */ > #define UART_IIR_MSI 0x00 /* - MODEM status */ > #define UART_IIR_BSY 0x07 /* - busy detect (DW) */ > +#define UART_IIR_FE 0xc0 /* FIFO enabled (2 bits) */ > > /* FIFO Control Register */ > -#define UART_FCR_ENABLE 0x01 /* enable FIFO */ > -#define UART_FCR_CLRX 0x02 /* clear Rx FIFO */ > -#define UART_FCR_CLTX 0x04 /* clear Tx FIFO */ > -#define UART_FCR_DMA 0x10 /* enter DMA mode */ > +#define UART_FCR_ENABLE BIT(0, U) /* enable FIFO */ > +#define UART_FCR_CLRX BIT(1, U) /* clear Rx FIFO */ > +#define UART_FCR_CLTX BIT(2, U) /* clear Tx FIFO */ > +#define UART_FCR_DMA BIT(3, U) /* enter DMA mode */ > +#define UART_FCR_RESERVED0 BIT(4, U) /* reserved; always 0 */ > +#define UART_FCR_RESERVED1 BIT(5, U) /* reserved; always 0 */ > +#define UART_FCR_RTB0 BIT(6, U) /* receiver trigger bit #0 */ > +#define UART_FCR_RTB1 BIT(7, U) /* receiver trigger bit #1 */ > +#define UART_FCR_TRG_MASK (UART_FCR_RTB0 | UART_FCR_RTB1) > + > #define UART_FCR_TRG1 0x00 /* Rx FIFO trig lev 1 */ > #define UART_FCR_TRG4 0x40 /* Rx FIFO trig lev 4 */ > #define UART_FCR_TRG8 0x80 /* Rx FIFO trig lev 8 */ > @@ -96,11 +106,32 @@ > #define UART_LCR_CONF_MODE_B 0xBF /* Configuration mode B */ > > /* Modem Control Register */ > -#define UART_MCR_DTR 0x01 /* Data Terminal Ready */ > -#define UART_MCR_RTS 0x02 /* Request to Send */ > -#define UART_MCR_OUT2 0x08 /* OUT2: interrupt mask */ > -#define UART_MCR_LOOP 0x10 /* Enable loopback test mode */ > -#define UART_MCR_TCRTLR 0x40 /* Access TCR/TLR (TI16C752, EFR[4]=1) */ > +#define UART_MCR_DTR BIT(0, U) /* Data Terminal Ready */ > +#define UART_MCR_RTS BIT(1, U) /* Request to Send */ > +#define UART_MCR_OUT1 BIT(2, U) /* OUT1: interrupt mask */
is OUT1 an interrupt mask actually? > +#define UART_MCR_OUT2 BIT(3, U) /* OUT2: interrupt mask */ > +#define UART_MCR_LOOP BIT(4, U) /* Enable loopback test mode */ > +#define UART_MCR_RESERVED0 BIT(5, U) /* Reserved #0 */ > +#define UART_MCR_TCRTLR BIT(6, U) /* Access TCR/TLR (TI16C752, > EFR[4]=1) */ > +#define UART_MCR_RESERVED1 BIT(7, U) /* Reserved #1 */ > +#define UART_MCR_MASK \ > + (UART_MCR_DTR | UART_MCR_RTS | \ > + UART_MCR_OUT1 | UART_MCR_OUT2 | \ > + UART_MCR_LOOP | UART_MCR_TCRTLR) > + > +/* Modem Status Register */ > +#define UART_MSR_DCTS BIT(0, U) /* Change in CTS */ > +#define UART_MSR_DDSR BIT(1, U) /* Change in DSR */ > +#define UART_MSR_TERI BIT(2, U) /* Change in RI */ > +#define UART_MSR_DDCD BIT(3, U) /* Change in CTS */ Changes in DCD, can be done on commit > +#define UART_MSR_CTS BIT(4, U) > +#define UART_MSR_DSR BIT(5, U) > +#define UART_MSR_RI BIT(6, U) > +#define UART_MSR_DCD BIT(7, U) > +#define UART_MSR_CHANGE \ > + (UART_MSR_DCTS | UART_MSR_DDSR | UART_MSR_TERI | UART_MSR_DDCD) > +#define UART_MSR_STATUS \ > + (UART_MSR_CTS | UART_MSR_DSR | UART_MSR_RI | UART_MSR_DCD) > > /* Line Status Register */ > #define UART_LSR_DR 0x01 /* Data ready */ > @@ -111,6 +142,7 @@ > #define UART_LSR_THRE 0x20 /* Xmit hold reg empty */ > #define UART_LSR_TEMT 0x40 /* Xmitter empty */ > #define UART_LSR_ERR 0x80 /* Error */ > +#define UART_LSR_MASK (UART_LSR_OE | UART_LSR_BI) > > /* These parity settings can be ORed directly into the LCR. */ > #define UART_PARITY_NONE (0<<3) > -- > 2.51.0 >
