first steps towards (optional) serial mouse support

1 files changed, 99 insertions, 18 deletions

diff --git a/serial.h b/serial.h
index beeaf50..1ddc317 100644
--- a/serial.h
+++ b/serial.h
@@ -2,6 +2,7 @@
 #define SERIAL_H
 
 #include <stdint.h>
+#include <conio.h>
 
 #include "bda.h"
 
@@ -12,6 +13,7 @@ enum SERIAL_UART_REGS {
 	SERIAL_DIVISOR_LO = 0,
 	/** (only with DLAB enabled) MSB of divisor/baud rate */
 	SERIAL_DIVISOR_HI = 1,
+	SERIAL_DIVISOR = SERIAL_DIVISOR_LO,
 	/** Interrupt Enable Register(read/write) */
 	SERIAL_IER = 1,
 	/** Fifo Control Register (write-only) */
@@ -45,6 +47,19 @@ enum SERIAL_DIVISOR {
 	SERIAL_DIVISOR_1200 = 96
 };
 
+enum SERIAL_IER {
+	/** No interrupts */
+	SERIAL_IER_NONE = 0,
+	/** Enable Receiver Buffer Full Interrupt */
+	SERIAL_IER_ERBFI = 1 << 0,
+	/** Enable Transmitter Buffer Empty Interrupt */
+	SERIAL_IER_ETBEI = 1 << 1,
+	/** Enable Line Status Interrupt */
+	SERIAL_IER_ELSI  = 1 << 2,
+	/** Enable Delta Status Signals Interrupt */
+	SERIAL_IER_EDSSI = 1 << 3,
+};
+
 enum SERIAL_FCR {
 	SERIAL_FCR_RX_TRIGER_1  = 0 << 6,
 	SERIAL_FCR_RX_TRIGER_4  = 1 << 6,
@@ -54,6 +69,31 @@ enum SERIAL_FCR {
 	SERIAL_FCR_TX_RESET    = 1 << 2,
 	SERIAL_FCR_RX_RESET    = 1 << 1,
 	SERIAL_FCR_FIFO_ENABLE = 1 << 0,
+	SERIAL_FCR_FIFO_RESET = SERIAL_FCR_TX_RESET | SERIAL_FCR_RX_RESET,
+	SERIAL_FCR_FIFO_DISABLE = 0
+};
+
+enum SERIAL_IIR {
+	/** Mask for retrieving the interrupt that occured. See enum SERIAL_IID. */
+	SERIAL_IIR_ID = 0xF,
+
+	SERIAL_IIR_FIFO1 = 1 << 6,
+	SERIAL_IIR_FIFO2 = 1 << 7,
+};
+
+enum SERIAL_IID {
+	/** No interrupt. */
+	SERIAL_IID_NONE = 1,
+	/** Highest priority: line error. OE, PE, etc. Serviced by reading LSR. */
+	SERIAL_IID_ERROR = 6,
+	/** Second highest priority: data received or trigger reached. Serviced by reading data. */
+	SERIAL_IID_DATA = 4,
+	/** Second highest priority: stale data in FIFO. Serviced by reading data. */
+	SERIAL_IID_STALE = 0xC,
+	/** Third priority: transmitter buffer has room. Serviced by reading this reg/writing. */
+	SERIAL_IID_THRE = 2,
+	/** Fourth priority: MSR change. Serviced by reading MSR. */
+	SERIAL_IID_MODEM = 0,
 };
 
 enum SERIAL_LCR {
@@ -115,14 +155,14 @@ enum SERIAL_MSR {
 
 struct serial_config
 {
-	uint8_t divisor_lo, divisor_hi;
+	uint16_t divisor;
 	uint8_t ier, lcr, mcr;
 };
 
 static unsigned serial_num_ports()
 {
-	uint8_t equipment = bda_get_byte(0x11);
-	uint8_t numports = (equipment & 0xE) >> 1;
+	uint16_t equipment = bda_get_equipment();
+	uint8_t numports = (equipment & 0xE00) >> 9;
 	return numports;
 }
 
@@ -131,11 +171,31 @@ static uint16_t serial_get_iobase(unsigned port)
 	uint16_t bdaport = bda_get_word((port - 1) * 2);
 	if (bdaport > 10) {
 		return bdaport;
-	} else if (port == 1) {
-		// Even if BIOS says no, hardcode the basic COM1 port at least.
+	}
+
+	// Even if BIOS says no, hardcode basic COM1/COM2 at least.
+	switch (port) {
+	case 1:
 		return 0x3F8;
+	case 2:
+		return 0x2F8;
+	default:
+		return 0;
+	}
+}
+
+static uint8_t serial_get_irq(unsigned port)
+{
+	switch (port) {
+	case 1:
+	case 3:
+		return 4;
+	case 2:
+	case 4:
+		return 3;
+	default:
+		return 0;
 	}
-	return 0;
 }
 
 static void serial_save_config(unsigned iobase, struct serial_config *config)
@@ -145,8 +205,7 @@ static void serial_save_config(unsigned iobase, struct serial_config *config)
 	config->mcr = inp(iobase + SERIAL_MCR);
 	// Set DLAB so that we can read divisor
 	outp(iobase + SERIAL_LCR, config->lcr | SERIAL_LCR_DLAB);
-	config->divisor_lo = inp(iobase + SERIAL_DIVISOR_LO);
-	config->divisor_hi = inp(iobase + SERIAL_DIVISOR_HI);
+	config->divisor = inpw(iobase + SERIAL_DIVISOR);
 	// Restore DLAB to whatever it was
 	outp(iobase + SERIAL_LCR, config->lcr);
 }
@@ -154,22 +213,34 @@ static void serial_save_config(unsigned iobase, struct serial_config *config)
 static void serial_restore_config(unsigned iobase, const struct serial_config *config)
 {
 	outp(iobase + SERIAL_LCR, config->lcr | SERIAL_LCR_DLAB);
-	outp(iobase + SERIAL_DIVISOR_LO, config->divisor_lo);
-	outp(iobase + SERIAL_DIVISOR_HI, config->divisor_hi);
+	outpw(iobase + SERIAL_DIVISOR, config->divisor);
 	outp(iobase + SERIAL_LCR, config->lcr);
 	outp(iobase + SERIAL_MCR, config->mcr);
 	outp(iobase + SERIAL_IER, config->ier);
 }
 
-static void serial_configure(unsigned iobase, uint16_t divisor, uint8_t lcr)
+/// Configure line characteristics (speed, databytes, etc.)
+/// Disables interrupts
+static void serial_configure_line(unsigned iobase, uint16_t divisor, uint8_t lcr)
 {
-	outp(iobase + SERIAL_IER, 0); // Disable all interrupts
 	outp(iobase + SERIAL_LCR, SERIAL_LCR_DLAB); // Enable DLAB and clear all other flags
-	outp(iobase + SERIAL_DIVISOR_LO, divisor);
-	outp(iobase + SERIAL_DIVISOR_HI, divisor >> 8);
+	outpw(iobase + SERIAL_DIVISOR, divisor);
 	outp(iobase + SERIAL_LCR, lcr); // This also disables DLAB
-	// Enable and reset both FIFOs
-	outp(iobase + SERIAL_FCR, SERIAL_FCR_RX_TRIGER_14|SERIAL_FCR_FIFO_ENABLE|SERIAL_FCR_RX_RESET|SERIAL_FCR_TX_RESET);
+}
+
+/// Configures when exceptions are going to be raised
+/// it also clears all pending interrupts
+/// and enables/disables the OUT2 gator here, which I'm not sure if is conceptually clean
+static void serial_configure_interrupts(unsigned iobase, uint8_t ier)
+{
+	uint8_t mcr = inp(iobase + SERIAL_MCR);
+	outp(iobase + SERIAL_IER, ier);
+	if (ier) {
+		mcr |= SERIAL_MCR_OUT2; // Actually enables IRQ line for this UART
+	} else {
+		mcr &= ~SERIAL_MCR_OUT2;
+	}
+	outp(iobase + SERIAL_MCR, mcr);
 }
 
 static inline void serial_set_modem_control(unsigned iobase, uint8_t mcr)
@@ -177,9 +248,14 @@ static inline void serial_set_modem_control(unsigned iobase, uint8_t mcr)
 	outp(iobase + SERIAL_MCR, mcr);
 }
 
-static inline void serial_set_modem_status(unsigned iobase, uint8_t msr)
+static inline void serial_set_fifo_control(unsigned iobase, uint8_t fcr)
 {
-	outp(iobase + SERIAL_MSR, msr);
+	outp(iobase + SERIAL_FCR, fcr);
+}
+
+static inline uint8_t serial_read_pending_interrupt(unsigned iobase)
+{
+	return inp(iobase + SERIAL_IIR) & SERIAL_IIR_ID;
 }
 
 static inline uint8_t serial_get_line_status(unsigned iobase)
@@ -187,6 +263,11 @@ static inline uint8_t serial_get_line_status(unsigned iobase)
 	return inp(iobase + SERIAL_LSR);
 }
 
+static inline uint8_t serial_get_modem_status(unsigned iobase)
+{
+	return inp(iobase + SERIAL_MSR);
+}
+
 static inline bool serial_data_ready(unsigned iobase)
 {
 	return serial_get_line_status(iobase) & SERIAL_LSR_DR;