Series comparison

-[PATCH] serial: sifive: Switch to nbcon console
+[PATCH v5] serial: sifive: Switch to nbcon console
 ...
 The ->device_lock()/unlock() will provide the additional serilization
 necessary for ->write_thread() which is called from dedicated printing
 thread.
 Signed-off-by: Ryo Takakura <ryotkkr98@gmail.com>
+Reviewed-by: John Ogness <john.ogness@linutronix.de>
 ---
-Hi!
+Changes since v1:
 [0] https://lore.kernel.org/lkml/20250323060603.388621-1-ryotkkr98@gmail.com/
-I referred to the already converted console drivers 8250 [0], imx [1]
+- Thank you John for the feedback!
-and amba-pl011 [2]. I tested the patch for each of the NBCON priority
+- Add a patch for synchronizing startup()/shutdown() vs write().
-(PANIC, EMERGENCY and NORMAL) on riscv qemu.
+- Add <Reviewed-by> by John.
 Hope to get feedbacks, thanks!
-Sincerely,
+Changes since v2:
-Ryo Takakura
+[1] https://lore.kernel.org/all/20250330003058.386447-1-ryotkkr98@gmail.com/
-[0] https://lore.kernel.org/lkml/20250107212702.169493-1-john.ogness@linutronix.de/
+- Add Cc stable for the first patch.
-[1] https://lore.kernel.org/linux-arm-kernel/20240913-serial-imx-nbcon-v3-1-4c627302335b@geanix.com/
-[2] https://lore.kernel.org/linux-serial/20250204044428.2191983-1-fj6611ie@aa.jp.fujitsu.com/
+Changes since v3:
 [2] https://lore.kernel.org/all/20250330110957.392460-1-ryotkkr98@gmail.com/
 - Avoid using return statement on return-void function. Thanks Sebastian
   for pointing out!
 Changes since v4:
 [3] https://lore.kernel.org/all/20250405043833.397020-1-ryotkkr98@gmail.com/
 - Send the 2 patches seperatly which used to be treated as a series.
   The other patch which was sent as part of the series can be found [4].
   [4] https://lore.kernel.org/all/20250405132458.488942-1-ryotkkr98@gmail.com/
 ---
  drivers/tty/serial/sifive.c | 87 +++++++++++++++++++++++++++++++------
 file changed, 74 insertions(+), 13 deletions(-)
 ...
 +
 +static void sifive_serial_device_lock(struct console *co, unsigned long *flags)
 +{
 +    struct uart_port *up = &sifive_serial_console_ports[co->index]->port;
 +
-+    return __uart_port_lock_irqsave(up, flags);
++    __uart_port_lock_irqsave(up, flags);
 +}
 +
 +static void sifive_serial_device_unlock(struct console *co, unsigned long flags)
 +{
 +    struct uart_port *up = &sifive_serial_console_ports[co->index]->port;
 +
-+    return __uart_port_unlock_irqrestore(up, flags);
++    __uart_port_unlock_irqrestore(up, flags);
  }
 -static void sifive_serial_console_write(struct console *co, const char *s,
 -                    unsigned int count)
 +static void sifive_serial_console_write_atomic(struct console *co,
 ...

Add the necessary callbacks(write_atomic, write_thread, device_lock
and device_unlock) and CON_NBCON flag to switch the sifive console
driver to perform as nbcon console.

Both ->write_atomic() and ->write_thread() will check for console
ownership whenever they are accessing registers.

The ->device_lock()/unlock() will provide the additional serilization
necessary for ->write_thread() which is called from dedicated printing
thread.

Signed-off-by: Ryo Takakura <ryotkkr98@gmail.com>
---

Hi!

I referred to the already converted console drivers 8250 [0], imx [1]
and amba-pl011 [2]. I tested the patch for each of the NBCON priority
(PANIC, EMERGENCY and NORMAL) on riscv qemu.
Hope to get feedbacks, thanks!

Sincerely,
Ryo Takakura

[0] https://lore.kernel.org/lkml/20250107212702.169493-1-john.ogness@linutronix.de/
[1] https://lore.kernel.org/linux-arm-kernel/20240913-serial-imx-nbcon-v3-1-4c627302335b@geanix.com/
[2] https://lore.kernel.org/linux-serial/20250204044428.2191983-1-fj6611ie@aa.jp.fujitsu.com/

---
 drivers/tty/serial/sifive.c | 87 +++++++++++++++++++++++++++++++------
 1 file changed, 74 insertions(+), 13 deletions(-)

diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
index XXXXXXX..XXXXXXX 100644
--- a/drivers/tty/serial/sifive.c
+++ b/drivers/tty/serial/sifive.c
@@ -XXX,XX +XXX,XX @@ struct sifive_serial_port {
 	unsigned long		baud_rate;
 	struct clk		*clk;
 	struct notifier_block	clk_notifier;
+	bool			console_line_ended;
 };
 
 /*
@@ -XXX,XX +XXX,XX @@ static void sifive_serial_console_putchar(struct uart_port *port, unsigned char
 
 	__ssp_wait_for_xmitr(ssp);
 	__ssp_transmit_char(ssp, ch);
+
+	ssp->console_line_ended = (ch == '\n');
+}
+
+static void sifive_serial_device_lock(struct console *co, unsigned long *flags)
+{
+	struct uart_port *up = &sifive_serial_console_ports[co->index]->port;
+
+	return __uart_port_lock_irqsave(up, flags);
+}
+
+static void sifive_serial_device_unlock(struct console *co, unsigned long flags)
+{
+	struct uart_port *up = &sifive_serial_console_ports[co->index]->port;
+
+	return __uart_port_unlock_irqrestore(up, flags);
 }
 
-static void sifive_serial_console_write(struct console *co, const char *s,
-					unsigned int count)
+static void sifive_serial_console_write_atomic(struct console *co,
+					       struct nbcon_write_context *wctxt)
 {
 	struct sifive_serial_port *ssp = sifive_serial_console_ports[co->index];
-	unsigned long flags;
+	struct uart_port *port = &ssp->port;
 	unsigned int ier;
-	int locked = 1;
 
 	if (!ssp)
 		return;
 
-	if (oops_in_progress)
-		locked = uart_port_trylock_irqsave(&ssp->port, &flags);
-	else
-		uart_port_lock_irqsave(&ssp->port, &flags);
+	if (!nbcon_enter_unsafe(wctxt))
+		return;
 
 	ier = __ssp_readl(ssp, SIFIVE_SERIAL_IE_OFFS);
 	__ssp_writel(0, SIFIVE_SERIAL_IE_OFFS, ssp);
 
-	uart_console_write(&ssp->port, s, count, sifive_serial_console_putchar);
+	if (!ssp->console_line_ended)
+		uart_console_write(port, "\n", 1, sifive_serial_console_putchar);
+	uart_console_write(port, wctxt->outbuf, wctxt->len,
+			   sifive_serial_console_putchar);
 
 	__ssp_writel(ier, SIFIVE_SERIAL_IE_OFFS, ssp);
 
-	if (locked)
-		uart_port_unlock_irqrestore(&ssp->port, flags);
+	nbcon_exit_unsafe(wctxt);
+}
+
+static void sifive_serial_console_write_thread(struct console *co,
+					       struct nbcon_write_context *wctxt)
+{
+	struct sifive_serial_port *ssp = sifive_serial_console_ports[co->index];
+	struct uart_port *port = &ssp->port;
+	unsigned int ier;
+
+	if (!ssp)
+		return;
+
+	if (!nbcon_enter_unsafe(wctxt))
+		return;
+
+	ier = __ssp_readl(ssp, SIFIVE_SERIAL_IE_OFFS);
+	__ssp_writel(0, SIFIVE_SERIAL_IE_OFFS, ssp);
+
+	if (nbcon_exit_unsafe(wctxt)) {
+		int len = READ_ONCE(wctxt->len);
+		int i;
+
+		for (i = 0; i < len; i++) {
+			if (!nbcon_enter_unsafe(wctxt))
+				break;
+
+			uart_console_write(port, wctxt->outbuf + i, 1,
+					   sifive_serial_console_putchar);
+
+			if (!nbcon_exit_unsafe(wctxt))
+				break;
+		}
+	}
+
+	while (!nbcon_enter_unsafe(wctxt))
+		nbcon_reacquire_nobuf(wctxt);
+
+	__ssp_writel(ier, SIFIVE_SERIAL_IE_OFFS, ssp);
+
+	nbcon_exit_unsafe(wctxt);
 }
 
 static int sifive_serial_console_setup(struct console *co, char *options)
@@ -XXX,XX +XXX,XX @@ static int sifive_serial_console_setup(struct console *co, char *options)
 	if (!ssp)
 		return -ENODEV;
 
+	ssp->console_line_ended = true;
+
 	if (options)
 		uart_parse_options(options, &baud, &parity, &bits, &flow);
 
@@ -XXX,XX +XXX,XX @@ static struct uart_driver sifive_serial_uart_driver;
 
 static struct console sifive_serial_console = {
 	.name		= SIFIVE_TTY_PREFIX,
-	.write		= sifive_serial_console_write,
+	.write_atomic	= sifive_serial_console_write_atomic,
+	.write_thread	= sifive_serial_console_write_thread,
+	.device_lock	= sifive_serial_device_lock,
+	.device_unlock	= sifive_serial_device_unlock,
 	.device		= uart_console_device,
 	.setup		= sifive_serial_console_setup,
-	.flags		= CON_PRINTBUFFER,
+	.flags		= CON_PRINTBUFFER | CON_NBCON,
 	.index		= -1,
 	.data		= &sifive_serial_uart_driver,
 };
-- 
2.34.1

Add the necessary callbacks(write_atomic, write_thread, device_lock
and device_unlock) and CON_NBCON flag to switch the sifive console
driver to perform as nbcon console.

Both ->write_atomic() and ->write_thread() will check for console
ownership whenever they are accessing registers.

The ->device_lock()/unlock() will provide the additional serilization
necessary for ->write_thread() which is called from dedicated printing
thread.

Signed-off-by: Ryo Takakura <ryotkkr98@gmail.com>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
---

Changes since v1:
[0] https://lore.kernel.org/lkml/20250323060603.388621-1-ryotkkr98@gmail.com/

- Thank you John for the feedback!
- Add a patch for synchronizing startup()/shutdown() vs write().
- Add <Reviewed-by> by John.

Changes since v2:
[1] https://lore.kernel.org/all/20250330003058.386447-1-ryotkkr98@gmail.com/

- Add Cc stable for the first patch.

Changes since v3:
[2] https://lore.kernel.org/all/20250330110957.392460-1-ryotkkr98@gmail.com/

- Avoid using return statement on return-void function. Thanks Sebastian
  for pointing out!

Changes since v4:
[3] https://lore.kernel.org/all/20250405043833.397020-1-ryotkkr98@gmail.com/

- Send the 2 patches seperatly which used to be treated as a series. 
  The other patch which was sent as part of the series can be found [4].
  [4] https://lore.kernel.org/all/20250405132458.488942-1-ryotkkr98@gmail.com/

---
 drivers/tty/serial/sifive.c | 87 +++++++++++++++++++++++++++++++------
 1 file changed, 74 insertions(+), 13 deletions(-)

diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
index XXXXXXX..XXXXXXX 100644
--- a/drivers/tty/serial/sifive.c
+++ b/drivers/tty/serial/sifive.c
@@ -XXX,XX +XXX,XX @@ struct sifive_serial_port {
 	unsigned long		baud_rate;
 	struct clk		*clk;
 	struct notifier_block	clk_notifier;
+	bool			console_line_ended;
 };
 
 /*
@@ -XXX,XX +XXX,XX @@ static void sifive_serial_console_putchar(struct uart_port *port, unsigned char
 
 	__ssp_wait_for_xmitr(ssp);
 	__ssp_transmit_char(ssp, ch);
+
+	ssp->console_line_ended = (ch == '\n');
+}
+
+static void sifive_serial_device_lock(struct console *co, unsigned long *flags)
+{
+	struct uart_port *up = &sifive_serial_console_ports[co->index]->port;
+
+	__uart_port_lock_irqsave(up, flags);
+}
+
+static void sifive_serial_device_unlock(struct console *co, unsigned long flags)
+{
+	struct uart_port *up = &sifive_serial_console_ports[co->index]->port;
+
+	__uart_port_unlock_irqrestore(up, flags);
 }
 
-static void sifive_serial_console_write(struct console *co, const char *s,
-					unsigned int count)
+static void sifive_serial_console_write_atomic(struct console *co,
+					       struct nbcon_write_context *wctxt)
 {
 	struct sifive_serial_port *ssp = sifive_serial_console_ports[co->index];
-	unsigned long flags;
+	struct uart_port *port = &ssp->port;
 	unsigned int ier;
-	int locked = 1;
 
 	if (!ssp)
 		return;
 
-	if (oops_in_progress)
-		locked = uart_port_trylock_irqsave(&ssp->port, &flags);
-	else
-		uart_port_lock_irqsave(&ssp->port, &flags);
+	if (!nbcon_enter_unsafe(wctxt))
+		return;
 
 	ier = __ssp_readl(ssp, SIFIVE_SERIAL_IE_OFFS);
 	__ssp_writel(0, SIFIVE_SERIAL_IE_OFFS, ssp);
 
-	uart_console_write(&ssp->port, s, count, sifive_serial_console_putchar);
+	if (!ssp->console_line_ended)
+		uart_console_write(port, "\n", 1, sifive_serial_console_putchar);
+	uart_console_write(port, wctxt->outbuf, wctxt->len,
+			   sifive_serial_console_putchar);
 
 	__ssp_writel(ier, SIFIVE_SERIAL_IE_OFFS, ssp);
 
-	if (locked)
-		uart_port_unlock_irqrestore(&ssp->port, flags);
+	nbcon_exit_unsafe(wctxt);
+}
+
+static void sifive_serial_console_write_thread(struct console *co,
+					       struct nbcon_write_context *wctxt)
+{
+	struct sifive_serial_port *ssp = sifive_serial_console_ports[co->index];
+	struct uart_port *port = &ssp->port;
+	unsigned int ier;
+
+	if (!ssp)
+		return;
+
+	if (!nbcon_enter_unsafe(wctxt))
+		return;
+
+	ier = __ssp_readl(ssp, SIFIVE_SERIAL_IE_OFFS);
+	__ssp_writel(0, SIFIVE_SERIAL_IE_OFFS, ssp);
+
+	if (nbcon_exit_unsafe(wctxt)) {
+		int len = READ_ONCE(wctxt->len);
+		int i;
+
+		for (i = 0; i < len; i++) {
+			if (!nbcon_enter_unsafe(wctxt))
+				break;
+
+			uart_console_write(port, wctxt->outbuf + i, 1,
+					   sifive_serial_console_putchar);
+
+			if (!nbcon_exit_unsafe(wctxt))
+				break;
+		}
+	}
+
+	while (!nbcon_enter_unsafe(wctxt))
+		nbcon_reacquire_nobuf(wctxt);
+
+	__ssp_writel(ier, SIFIVE_SERIAL_IE_OFFS, ssp);
+
+	nbcon_exit_unsafe(wctxt);
 }
 
 static int sifive_serial_console_setup(struct console *co, char *options)
@@ -XXX,XX +XXX,XX @@ static int sifive_serial_console_setup(struct console *co, char *options)
 	if (!ssp)
 		return -ENODEV;
 
+	ssp->console_line_ended = true;
+
 	if (options)
 		uart_parse_options(options, &baud, &parity, &bits, &flow);
 
@@ -XXX,XX +XXX,XX @@ static struct uart_driver sifive_serial_uart_driver;
 
 static struct console sifive_serial_console = {
 	.name		= SIFIVE_TTY_PREFIX,
-	.write		= sifive_serial_console_write,
+	.write_atomic	= sifive_serial_console_write_atomic,
+	.write_thread	= sifive_serial_console_write_thread,
+	.device_lock	= sifive_serial_device_lock,
+	.device_unlock	= sifive_serial_device_unlock,
 	.device		= uart_console_device,
 	.setup		= sifive_serial_console_setup,
-	.flags		= CON_PRINTBUFFER,
+	.flags		= CON_PRINTBUFFER | CON_NBCON,
 	.index		= -1,
 	.data		= &sifive_serial_uart_driver,
 };
-- 
2.34.1