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From: Ryo Takakura <ryotkkr98@gmail.com>
To: alex@ghiti.fr,
aou@eecs.berkeley.edu,
bigeasy@linutronix.de,
conor.dooley@microchip.com,
gregkh@linuxfoundation.org,
jirislaby@kernel.org,
john.ogness@linutronix.de,
palmer@dabbelt.com,
paul.walmsley@sifive.com,
pmladek@suse.com,
samuel.holland@sifive.com,
u.kleine-koenig@baylibre.com
Cc: linux-kernel@vger.kernel.org,
linux-riscv@lists.infradead.org,
linux-serial@vger.kernel.org,
Ryo Takakura <ryotkkr98@gmail.com>
Subject: [PATCH v2] serial: sifive: Switch to nbcon console
Date: Sat, 5 Apr 2025 23:59:15 +0900
Message-Id: <20250405145915.493173-1-ryotkkr98@gmail.com>
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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>
Reviewed-by: Petr Mladek <pmladek@suse.com>
---
This patch is once again sent as a standalone patch for converting sifive
driver to nbcon. It used to be sent as a part of series. The related fixes
along the way can be found [0].
Sincerely,
Ryo Takakura
[0] https://lore.kernel.org/all/20250405043833.397020-1-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 054a8e630..8f7f770ec 100644
--- a/drivers/tty/serial/sifive.c
+++ b/drivers/tty/serial/sifive.c
@@ -151,6 +151,7 @@ struct sifive_serial_port {
unsigned long baud_rate;
struct clk *clk;
struct notifier_block clk_notifier;
+ bool console_line_ended;
};
=20
/*
@@ -785,33 +786,88 @@ static void sifive_serial_console_putchar(struct uart=
_port *port, unsigned char
=20
__ssp_wait_for_xmitr(ssp);
__ssp_transmit_char(ssp, ch);
+
+ ssp->console_line_ended =3D (ch =3D=3D '\n');
+}
+
+static void sifive_serial_device_lock(struct console *co, unsigned long *f=
lags)
+{
+ struct uart_port *up =3D &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 =3D &sifive_serial_console_ports[co->index]->port;
+
+ __uart_port_unlock_irqrestore(up, flags);
}
=20
-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 =3D sifive_serial_console_ports[co->index];
- unsigned long flags;
+ struct uart_port *port =3D &ssp->port;
unsigned int ier;
- int locked =3D 1;
=20
if (!ssp)
return;
=20
- if (oops_in_progress)
- locked =3D uart_port_trylock_irqsave(&ssp->port, &flags);
- else
- uart_port_lock_irqsave(&ssp->port, &flags);
+ if (!nbcon_enter_unsafe(wctxt))
+ return;
=20
ier =3D __ssp_readl(ssp, SIFIVE_SERIAL_IE_OFFS);
__ssp_writel(0, SIFIVE_SERIAL_IE_OFFS, ssp);
=20
- 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);
=20
__ssp_writel(ier, SIFIVE_SERIAL_IE_OFFS, ssp);
=20
- 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 =3D sifive_serial_console_ports[co->index];
+ struct uart_port *port =3D &ssp->port;
+ unsigned int ier;
+
+ if (!ssp)
+ return;
+
+ if (!nbcon_enter_unsafe(wctxt))
+ return;
+
+ ier =3D __ssp_readl(ssp, SIFIVE_SERIAL_IE_OFFS);
+ __ssp_writel(0, SIFIVE_SERIAL_IE_OFFS, ssp);
+
+ if (nbcon_exit_unsafe(wctxt)) {
+ int len =3D READ_ONCE(wctxt->len);
+ int i;
+
+ for (i =3D 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);
}
=20
static int sifive_serial_console_setup(struct console *co, char *options)
@@ -829,6 +885,8 @@ static int sifive_serial_console_setup(struct console *=
co, char *options)
if (!ssp)
return -ENODEV;
=20
+ ssp->console_line_ended =3D true;
+
if (options)
uart_parse_options(options, &baud, &parity, &bits, &flow);
=20
@@ -839,10 +897,13 @@ static struct uart_driver sifive_serial_uart_driver;
=20
static struct console sifive_serial_console =3D {
.name =3D SIFIVE_TTY_PREFIX,
- .write =3D sifive_serial_console_write,
+ .write_atomic =3D sifive_serial_console_write_atomic,
+ .write_thread =3D sifive_serial_console_write_thread,
+ .device_lock =3D sifive_serial_device_lock,
+ .device_unlock =3D sifive_serial_device_unlock,
.device =3D uart_console_device,
.setup =3D sifive_serial_console_setup,
- .flags =3D CON_PRINTBUFFER,
+ .flags =3D CON_PRINTBUFFER | CON_NBCON,
.index =3D -1,
.data =3D &sifive_serial_uart_driver,
};
--=20
2.34.1