On 25. 10. 24, 12:57, John Ogness wrote:
Implement the necessary callbacks to switch the 8250 console driver
to perform as an nbcon console.
Add implementations for the nbcon console callbacks (write_atomic,
write_thread, device_lock, device_unlock) and add CON_NBCON to the
initial flags.
All register access in the callbacks are within unsafe sections.
The write callbacks allow safe handover/takeover per byte and add
a preceding newline if they take over mid-line.
For the write_atomic() case, a new irq_work is used to defer modem
control since it may be a context that does not allow waking up
tasks.
Signed-off-by: John Ogness <john.ogness@xxxxxxxxxxxxx>
---
drivers/tty/serial/8250/8250_core.c | 35 +++++-
drivers/tty/serial/8250/8250_port.c | 159 ++++++++++++++++++++++------
include/linux/serial_8250.h | 7 +-
3 files changed, 164 insertions(+), 37 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 5f9f06911795..7184100129bd 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -388,12 +388,34 @@ void __init serial8250_register_ports(struct uart_driver *drv, struct device *de
#ifdef CONFIG_SERIAL_8250_CONSOLE
-static void univ8250_console_write(struct console *co, const char *s,
- unsigned int count)
+static void univ8250_console_write_atomic(struct console *co,
Once 'co'.
+ struct nbcon_write_context *wctxt)
{
struct uart_8250_port *up = &serial8250_ports[co->index];
- serial8250_console_write(up, s, count);
+ serial8250_console_write(up, wctxt, true);
+}
+
+static void univ8250_console_write_thread(struct console *co,
Second time co.
+ struct nbcon_write_context *wctxt)
+{
+ struct uart_8250_port *up = &serial8250_ports[co->index];
+
+ serial8250_console_write(up, wctxt, false);
+}
+
+static void univ8250_console_device_lock(struct console *con, unsigned long *flags)
And suddenly, it is 'con'.
+{
+ struct uart_port *up = &serial8250_ports[con->index].port;
+
+ __uart_port_lock_irqsave(up, flags);
+}
+
+static void univ8250_console_device_unlock(struct console *con, unsigned long flags)
+{
+ struct uart_port *up = &serial8250_ports[con->index].port;
+
+ __uart_port_unlock_irqrestore(up, flags);
}
...
static void serial8250_console_putchar(struct uart_port *port, unsigned char ch)
{
+ struct uart_8250_port *up = up_to_u8250p(port);
+
serial_port_out(port, UART_TX, ch);
+
+ if (ch == '\n')
+ up->console_line_ended = true;
+ else
+ up->console_line_ended = false;
So simply:
up->console_line_ended = ch == '\n';
?
...
-void serial8250_console_write(struct uart_8250_port *up, const char *s,
- unsigned int count)
+void serial8250_console_write(struct uart_8250_port *up,
+ struct nbcon_write_context *wctxt,
+ bool is_atomic)
{
struct uart_8250_em485 *em485 = up->em485;
struct uart_port *port = &up->port;
- unsigned long flags;
- unsigned int ier, use_fifo;
- int locked = 1;
-
- touch_nmi_watchdog();
+ unsigned int ier;
+ bool use_fifo;
- if (oops_in_progress)
- locked = uart_port_trylock_irqsave(port, &flags);
- else
- uart_port_lock_irqsave(port, &flags);
+ if (!nbcon_enter_unsafe(wctxt))
+ return;
/*
- * First save the IER then disable the interrupts
+ * First save IER then disable the interrupts. The special variant
When you are at it:
"First, save the IER, then"
(BTW why did you remove the "the"?)
+ * to clear IER is used because console printing may occur without
+ * holding the port lock.
*/
ier = serial_port_in(port, UART_IER);
- serial8250_clear_IER(up);
+ __serial8250_clear_IER(up);
/* check scratch reg to see if port powered off during system sleep */
if (up->canary && (up->canary != serial_port_in(port, UART_SCR))) {
@@ -3497,6 +3593,9 @@ int serial8250_console_setup(struct uart_port *port, char *options, bool probe)
if (!port->iobase && !port->membase)
return -ENODEV;
+ up->console_line_ended = true;
+ up->modem_status_work = IRQ_WORK_INIT(modem_status_handler);
Looks weird ^^^.
Do:
init_irq_work(&up->modem_status_work, modem_status_handler)
thanks,
--
js
suse labs
