kern/console: implement console selection

4 files changed, 73 insertions, 23 deletions

diff --git a/arch/x86/machine/cga.c b/arch/x86/machine/cga.c
index 86a661cb..3b217ca1 100644
--- a/arch/x86/machine/cga.c
+++ b/arch/x86/machine/cga.c
@@ -191,6 +191,6 @@ cga_setup(void)
 
     cga_cursor = cga_get_cursor_position();
 
-    console_init(&cga_console, cga_console_putc);
+    console_init(&cga_console, "cga", cga_console_putc);
     console_register(&cga_console);
 }
diff --git a/arch/x86/machine/uart.c b/arch/x86/machine/uart.c
index 86ef1e3a..f17bc66e 100644
--- a/arch/x86/machine/uart.c
+++ b/arch/x86/machine/uart.c
@@ -67,6 +67,16 @@ static struct uart uart_devs[UART_MAX_DEVS];
 
 static uint16_t uart_intrs[UART_MAX_DEVS] = { 4, 3, 4, 3 };
 
+static size_t
+uart_get_id(const struct uart *uart)
+{
+    size_t id;
+
+    id = uart - uart_devs;
+    assert(id < ARRAY_SIZE(uart_devs));
+    return id;
+}
+
 static uint16_t
 uart_get_addr(const struct uart *uart, uint16_t reg)
 {
@@ -163,6 +173,7 @@ uart_console_putc(struct console *console, char c)
 static void __init
 uart_init(struct uart *uart, uint16_t port, uint16_t intr)
 {
+    char name[CONSOLE_NAME_SIZE];
     uint8_t byte;
 
     uart->port = port;
@@ -179,7 +190,8 @@ uart_init(struct uart *uart, uint16_t port, uint16_t intr)
     byte = UART_LCR_8BITS | UART_LCR_NP | UART_LCR_1S | UART_LCR_BEN;
     uart_write(uart, UART_REG_LCR, byte);
 
-    console_init(&uart->console, uart_console_putc);
+    snprintf(name, sizeof(name), "uart%zu", uart_get_id(uart));
+    console_init(&uart->console, name, uart_console_putc);
     console_register(&uart->console);
 }
 
diff --git a/kern/console.c b/kern/console.c
index 138a4248..eb1306f8 100644
--- a/kern/console.c
+++ b/kern/console.c
@@ -15,16 +15,48 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <stdbool.h>
 #include <stddef.h>
+#include <stdio.h>
+#include <string.h>
 
+#include <kern/arg.h>
 #include <kern/assert.h>
 #include <kern/init.h>
 #include <kern/console.h>
 #include <kern/list.h>
 #include <kern/spinlock.h>
 
+/*
+ * Registered consoles.
+ */
 static struct list console_devs;
-static struct spinlock console_lock;
+
+/*
+ * Active console device.
+ */
+static struct console *console_dev;
+
+static const char *console_name __initdata;
+
+static bool __init
+console_name_match(const char *name)
+{
+    if (console_name == NULL) {
+        return true;
+    }
+
+    return (strcmp(console_name, name) == 0);
+}
+
+void __init
+console_init(struct console *console, const char *name,
+             console_putc_fn putc)
+{
+    spinlock_init(&console->lock);
+    console->putc = putc;
+    strlcpy(console->name, name, sizeof(console->name));
+}
 
 static void
 console_putc(struct console *console, char c)
@@ -40,30 +72,31 @@ void __init
 console_setup(void)
 {
     list_init(&console_devs);
-    spinlock_init(&console_lock);
+    console_name = arg_value("console");
 }
 
 void __init
 console_register(struct console *console)
 {
-    assert(console->putc != NULL);
-
-    spinlock_lock(&console_lock);
     list_insert_tail(&console_devs, &console->node);
-    spinlock_unlock(&console_lock);
+
+    if ((console_dev == NULL) && console_name_match(console->name)) {
+        console_dev = console;
+    }
+
+    printf("console: %s registered\n", console->name);
+
+    if (console == console_dev) {
+        printf("console: %s selected as active console\n", console->name);
+    }
 }
 
 void
 console_write_char(char c)
 {
-    struct console *console;
-    unsigned long flags;
-
-    spinlock_lock_intr_save(&console_lock, &flags);
-
-    list_for_each_entry(&console_devs, console, node) {
-        console_putc(console, c);
+    if (console_dev == NULL) {
+        return;
     }
 
-    spinlock_unlock_intr_restore(&console_lock, flags);
+    console_putc(console_dev, c);
 }
diff --git a/kern/console.h b/kern/console.h
index 8fdef160..3087b711 100644
--- a/kern/console.h
+++ b/kern/console.h
@@ -31,25 +31,27 @@ struct console;
  */
 typedef void (*console_putc_fn)(struct console *console, char c);
 
+#define CONSOLE_NAME_SIZE   16
+
 /*
  * Console device.
  *
  * This structure should be embedded in the hardware-specific console
  * objects. Calls to console operations are all serialized by this module
- * for each device.
+ * for each device. Interrupts are disabled when calling operations.
  */
 struct console {
     struct spinlock lock;
     struct list node;
     console_putc_fn putc;
+    char name[CONSOLE_NAME_SIZE];
 };
 
-static inline void
-console_init(struct console *console, console_putc_fn putc)
-{
-    spinlock_init(&console->lock);
-    console->putc = putc;
-}
+/*
+ * Console initialization.
+ */
+void console_init(struct console *console, const char *name,
+                  console_putc_fn putc);
 
 /*
  * Initialize the console module.
@@ -60,6 +62,9 @@ void console_setup(void);
  * Register a console device.
  *
  * The given console must be initialized before calling this function.
+ *
+ * This function isn't thread-safe and can only be called during system
+ * initialization.
  */
 void console_register(struct console *console);