Add boot time configuration for UART devices

common/cmdline.c

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021 Amazon.com, Inc. or its affiliates.
+ * Copyright (c) 2022 Open Source Security, Inc.
  * All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -24,6 +25,7 @@
  */
 
 #include <cmdline.h>
+#include <drivers/serial.h>
 #include <ktf.h>
 #include <mm/regions.h>
 #include <string.h>
@@ -56,6 +58,18 @@ bool_cmd("qemu_console", opt_qemu_console);
 bool opt_poweroff = true;
 bool_cmd("poweroff", opt_poweroff);
 
+static char opt_com1[20];
+string_cmd("com1", opt_com1);
+
+static char opt_com2[20];
+string_cmd("com2", opt_com2);
+
+static char opt_com3[20];
+string_cmd("com3", opt_com3);
+
+static char opt_com4[20];
+string_cmd("com4", opt_com4);
+
 const char *kernel_cmdline;
 
 void __text_init cmdline_parse(const char *cmdline) {
@@ -116,3 +130,182 @@ void __text_init cmdline_parse(const char *cmdline) {
         }
     }
 }
+
+static __text_init bool _parse_com_port(char *port_str, io_port_t *port) {
+    unsigned long tmp;
+
+    if (string_empty(port_str))
+        return false;
+
+    tmp = strtoul(port_str, NULL, 16);
+    switch (tmp) {
+    case COM1_PORT:
+    case COM2_PORT:
+    case COM3_PORT:
+    case COM4_PORT:
+        *port = tmp;
+        break;
+    default:
+        return false;
+    }
+
+    return true;
+}
+
+static __text_init bool _parse_com_baud(char *baud_str, com_baud_t *baud) {
+    unsigned long tmp;
+
+    if (string_empty(baud_str))
+        return false;
+
+    tmp = strtoul(baud_str, NULL, 0);
+    switch (tmp) {
+    case COM_BAUD_300:
+    case COM_BAUD_1200:
+    case COM_BAUD_2400:
+    case COM_BAUD_4800:
+    case COM_BAUD_9600:
+    case COM_BAUD_19200:
+    case COM_BAUD_38400:
+    case COM_BAUD_57600:
+    case COM_BAUD_115200:
+        *baud = tmp;
+        break;
+    default:
+        return false;
+    }
+
+    return true;
+}
+
+static __text_init bool _parse_com_width(char *frame_size_str,
+                                         com_frame_size_t *frame_size) {
+    unsigned long tmp;
+
+    if (string_empty(frame_size_str))
+        return false;
+
+    tmp = strtoul(frame_size_str, NULL, 0);
+    switch (tmp) {
+    case 8:
+        *frame_size = COM_FRAME_SIZE_8_BITS;
+        break;
+    case 7:
+        *frame_size = COM_FRAME_SIZE_7_BITS;
+        break;
+    case 6:
+        *frame_size = COM_FRAME_SIZE_6_BITS;
+        break;
+    case 5:
+        *frame_size = COM_FRAME_SIZE_5_BITS;
+        break;
+    default:
+        return false;
+    }
+
+    return true;
+}
+
+static __text_init bool _parse_com_parity(char *parity_str, com_parity_t *parity) {
+    if (string_empty(parity_str) || strlen(parity_str) > 1)
+        return false;
+
+    switch (parity_str[0]) {
+    case 'n':
+        *parity = COM_NO_PARITY;
+        break;
+    case 'o':
+        *parity = COM_ODD_PARITY;
+        break;
+    case 'e':
+        *parity = COM_EVEN_PARITY;
+        break;
+    case 'h':
+        *parity = COM_HIGH_PARITY;
+        break;
+    case 'l':
+        *parity = COM_LOW_PARITY;
+        break;
+    default:
+        return false;
+    }
+
+    return true;
+}
+
+static __text_init bool _parse_com_stop_bit(char *stop_bit_str,
+                                            com_stop_bit_t *stop_bit) {
+    unsigned long tmp;
+
+    if (string_empty(stop_bit_str))
+        return false;
+
+    tmp = strtoul(stop_bit_str, NULL, 0);
+    switch (tmp) {
+    case 1:
+        *stop_bit = COM_STOP_BIT_1;
+        break;
+    case 2:
+        *stop_bit = COM_STOP_BIT_2;
+        break;
+    default:
+        return false;
+    }
+
+    return true;
+}
+
+__text_init bool parse_com_port(com_idx_t com, uart_config_t *cfg) {
+    char *tmp_str = NULL;
+    char *opt_com;
+
+    switch (com) {
+    case COM1:
+        opt_com = opt_com1;
+        break;
+    case COM2:
+        opt_com = opt_com2;
+        break;
+    case COM3:
+        opt_com = opt_com3;
+        break;
+    case COM4:
+        opt_com = opt_com4;
+        break;
+    default:
+        return false;
+    }
+
+    if (string_empty(opt_com))
+        return false;
+
+    tmp_str = strtok(opt_com, ",");
+    if (!_parse_com_port(tmp_str, &cfg->port))
+        return false;
+
+    tmp_str = strtok(NULL, ",");
+    if (string_empty(tmp_str))
+        cfg->baud = DEFAULT_BAUD_SPEED;
+    else if (!_parse_com_baud(tmp_str, &cfg->baud))
+        return false;
+
+    tmp_str = strtok(NULL, ",");
+    if (string_empty(tmp_str))
+        cfg->frame_size = COM_FRAME_SIZE_8_BITS;
+    else if (!_parse_com_width(tmp_str, &cfg->frame_size))
+        return false;
+
+    tmp_str = strtok(NULL, ",");
+    if (string_empty(tmp_str))
+        cfg->parity = COM_NO_PARITY;
+    else if (!_parse_com_parity(tmp_str, &cfg->parity))
+        return false;
+
+    tmp_str = strtok(NULL, ",");
+    if (string_empty(tmp_str))
+        cfg->stop_bit = COM_STOP_BIT_1;
+    else if (!_parse_com_stop_bit(tmp_str, &cfg->stop_bit))
+        return false;
+
+    return true;
+}

common/setup.c

@@ -60,8 +60,6 @@
 #include <perfmon/pfmlib.h>
 #endif
 
-io_port_t __data_rmode com_ports[2] = {COM1_PORT, COM2_PORT};
-
 boot_flags_t boot_flags;
 
 static unsigned bsp_cpu_id = 0;
@@ -70,18 +68,28 @@ unsigned get_bsp_cpu_id(void) { return bsp_cpu_id; }
 void set_bsp_cpu_id(unsigned cpu_id) { bsp_cpu_id = cpu_id; }
 
 #define QEMU_CONSOLE_PORT 0x0e9
-static void __text_init init_console(void) {
-    get_com_ports();
-
-    uart_init(com_ports[0], DEFAULT_BAUD_SPEED);
-    register_console_callback(serial_console_write, _ptr(com_ports[0]));
 
-    printk("COM1: %x, COM2: %x\n", com_ports[0], com_ports[1]);
+static void __text_init init_console(void) {
+    uart_config_t cfg = {0};
+
+    if (!parse_com_port(COM1, &cfg)) {
+        /* Use first COM port indicated by BIOS (if none, use COM1) */
+        cfg.port = get_first_com_port();
+        cfg.baud = DEFAULT_BAUD_SPEED;
+        cfg.frame_size = COM_FRAME_SIZE_8_BITS;
+        cfg.parity = COM_NO_PARITY;
+        cfg.stop_bit = COM_STOP_BIT_1;
+    }
+    init_uart(&cfg);
+    register_console_callback(serial_console_write, _ptr(cfg.port));
 
     if (opt_qemu_console) {
         register_console_callback(qemu_console_write, _ptr(QEMU_CONSOLE_PORT));
         printk("Initialized QEMU console at port 0x%x", QEMU_CONSOLE_PORT);
     }
+
+    printk("Serial console at: ");
+    display_uart_config(&cfg);
 }
 
 static __always_inline void zero_bss(void) {
@@ -218,7 +226,7 @@ void __noreturn __text_init kernel_start(uint32_t multiboot_magic,
     init_pci();
 
     /* Initialize console input */
-    uart_input_init(get_bsp_cpu_id());
+    init_uart_input(get_bsp_cpu_id());
 
     /* Initialize timers */
     bool hpet_initialized = false;

drivers/serial.c

@@ -37,14 +37,53 @@ static struct {
     unsigned init;
 } input_state;
 
-extern io_port_t com_ports[2];
+io_port_t __data_rmode com_ports[4];
+
+static inline const char *com_port_name(com_port_t port) {
+    switch (port) {
+    case COM1_PORT:
+        return "COM1";
+    case COM2_PORT:
+        return "COM2";
+    case COM3_PORT:
+        return "COM3";
+    case COM4_PORT:
+        return "COM4";
+    default:
+        BUG();
+    }
+}
 
-static inline void set_port_mode(io_port_t port, bool stop_bit, uint8_t width) {
-    lcr_t lcr = {0};
+static const uint8_t com_frame_size_values[] = {
+    [COM_FRAME_SIZE_5_BITS] = 5,
+    [COM_FRAME_SIZE_6_BITS] = 6,
+    [COM_FRAME_SIZE_7_BITS] = 7,
+    [COM_FRAME_SIZE_8_BITS] = 8,
+};
 
-    lcr.stop_bit = stop_bit;
-    lcr.width = width;
-    outb(port + UART_LCR_REG_OFFSET, lcr.reg);
+static const char com_parity_names[] = {
+    [COM_NO_PARITY] = 'n',   [COM_ODD_PARITY] = 'o', [COM_EVEN_PARITY] = 'e',
+    [COM_HIGH_PARITY] = 'h', [COM_LOW_PARITY] = 'l',
+};
+
+#define COM_STOP_BIT_VALUE(cfg) ((cfg)->stop_bit + 1)
+
+void display_uart_config(const uart_config_t *cfg) {
+    printk("[%s] 0x%x %u,%u%c%u\n", com_port_name(cfg->port), cfg->port, cfg->baud,
+           com_frame_size_values[cfg->frame_size], com_parity_names[cfg->parity],
+           COM_STOP_BIT_VALUE(cfg));
+}
+
+io_port_t get_first_com_port(void) {
+    memcpy((void *) com_ports, _ptr(BDA_COM_PORTS_ENTRY), sizeof(com_ports));
+
+    for (unsigned int i = 0; i < ARRAY_SIZE(com_ports); i++) {
+        if (com_ports[i] != 0x0)
+            return com_ports[i];
+    }
+
+    /* Fallback to COM1 */
+    return COM1_PORT;
 }
 
 static inline void set_dlab(io_port_t port, bool dlab) {
@@ -55,6 +94,21 @@ static inline void set_dlab(io_port_t port, bool dlab) {
     outb(port + UART_LCR_REG_OFFSET, lcr.reg);
 }
 
+static inline void set_port_mode(uart_config_t *cfg) {
+    lcr_t lcr = {0};
+
+    lcr.stop_bit = cfg->stop_bit;
+    lcr.width = cfg->frame_size;
+    lcr.parity = cfg->parity;
+
+    outb(cfg->port + UART_LCR_REG_OFFSET, lcr.reg);
+
+    /* Set baud speed by applying divisor to DLL+DLH */
+    set_dlab(cfg->port, true);
+    outw(cfg->port + UART_DLL_REG_OFFSET, DEFAULT_BAUD_SPEED / cfg->baud);
+    set_dlab(cfg->port, false);
+}
+
 static inline bool thr_empty(io_port_t port) {
     lsr_t lsr;
 
@@ -71,30 +125,25 @@ static inline bool receiver_ready(io_port_t port) {
     return msr.dsr && msr.cts;
 }
 
-void uart_init(io_port_t port, unsigned baud) {
+void __text_init init_uart(uart_config_t *cfg) {
     mcr_t mcr = {0};
 
     /* Enable interrupts for received data available */
-    outb(port + UART_IER_REG_OFFSET, 0x01);
+    outb(cfg->port + UART_IER_REG_OFFSET, 0x01);
 
     /* Disable FIFO control */
-    outb(port + UART_FCR_REG_OFFSET, 0x00);
+    outb(cfg->port + UART_FCR_REG_OFFSET, 0x00);
 
     /* Set 8n1 mode */
-    set_port_mode(port, STOP_BIT_1, FRAME_SIZE_8_BITS);
-
-    /* Set baud speed by applying divisor to DLL+DLH */
-    set_dlab(port, true);
-    outw(port + UART_DLL_REG_OFFSET, DEFAULT_BAUD_SPEED / baud);
-    set_dlab(port, false);
+    set_port_mode(cfg);
 
     /* Set tx/rx ready state */
     mcr.dtr = 1;
     mcr.rts = 1;
-    outb(port + UART_MCR_REG_OFFSET, mcr.reg);
+    outb(cfg->port + UART_MCR_REG_OFFSET, mcr.reg);
 }
 
-void uart_input_init(uint8_t dst_cpus) {
+void __text_init init_uart_input(uint8_t dst_cpus) {
     /* Initialize input state */
     memset(&input_state, 0, sizeof(input_state));
 

grub/boot/grub/grub.cfg

@@ -5,6 +5,6 @@ terminal_input --append serial
 terminal_output --append serial
 
 menuentry "kernel64" {
-   multiboot /boot/kernel64.bin poweroff=1
+   multiboot /boot/kernel64.bin poweroff=1 com1=0x3f8,115200,8,n,1
    boot
 }