[PATCH v7 02/16] xen/8250-uart: update definitions

[dmukhin@xxxxxxx]

From: Denis Mukhin <dmukhin@xxxxxxxx> 

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 <dmukhin@xxxxxxxx>
---
Changes since v6:
- used raw bitmasks instead of BIT() for consistency
---
 xen/drivers/char/ns16550.c  | 16 ++++++++--------
 xen/include/xen/8250-uart.h | 36 ++++++++++++++++++++++++++++++++++--
 2 files changed, 42 insertions(+), 10 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..a8a26b64689e 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_DMA      0x08    /* enter DMA mode       */
+#define UART_FCR_RSRVD0   0x10    /* reserved; always 0   */
+#define UART_FCR_RSRVD1   0x20    /* reserved; always 0   */
+#define UART_FCR_RTB0     0x40    /* receiver trigger bit #0 */
+#define UART_FCR_RTB1     0x80    /* 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   */
@@ -98,9 +108,30 @@
 /* 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_OUT1     0x04    /* Output #1 */
+#define UART_MCR_OUT2     0x08    /* Output #2 */
 #define UART_MCR_LOOP     0x10    /* Enable loopback test mode */
+#define UART_MCR_RSRVD0   0x20    /* Reserved #0 */
 #define UART_MCR_TCRTLR   0x40    /* Access TCR/TLR (TI16C752, EFR[4]=1) */
+#define UART_MCR_RSRVD1   0x80    /* 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     0x01    /* Change in CTS */
+#define UART_MSR_DDSR     0x02    /* Change in DSR */
+#define UART_MSR_TERI     0x04    /* Change in RI */
+#define UART_MSR_DDCD     0x08    /* Change in DCD */
+#define UART_MSR_CTS      0x10
+#define UART_MSR_DSR      0x20
+#define UART_MSR_RI       0x40
+#define UART_MSR_DCD      0x80
+#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