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[60.39.60.229]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-229785c020dsm49579655ad.100.2025.04.05.06.35.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 05 Apr 2025 06:35:26 -0700 (PDT) From: Ryo Takakura 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 Subject: [PATCH v5] serial: sifive: Switch to nbcon console Date: Sat, 5 Apr 2025 22:34:50 +0900 Message-Id: <20250405133450.489780-1-ryotkkr98@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 Reviewed-by: John Ogness --- Changes since v1: [0] https://lore.kernel.org/lkml/20250323060603.388621-1-ryotkkr98@gmail.co= m/ - Thank you John for the feedback! - Add a patch for synchronizing startup()/shutdown() vs write(). - Add 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.=20 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.c= om/ --- 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