From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EF5C563CB; Wed, 30 Oct 2024 06:33:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730270010; cv=none; b=Dg0SzucxGmEID8cP3Ddwk2Jpudn4xix8Ot6f8/0h2lNMDlp+IoEWjHJlsxojPsRF2s5tCAsOCPaXA9UIrscNGSXfHUm0z/KlPGyRVF9yFd8P2TE368Ah+bxhLmyvIGK2h0QRNLfkcTzosCAxVzKUVFgJwl3x1KggP8+SnoQ4U1o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730270010; c=relaxed/simple; bh=SC0Xu24Wqh43ElDcUACTlpmVLeS1VgEZ9q2pTiK0tTQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=lmwy4N3F1RGJc6upUleMq2q93ykz/zDukHrYtDsH+OHnSbTxq8kfsrVvO+MCVZySpIB44fiGHY58owUb3/q9tsrcDkbrTPd/KhOkH4DB7qz80g+QPECbnIxF3sMf60n3N4f6QuSdtveJCpET8r8FyUrdikTqoB42UbL6Wdp9HCM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kf3J6PxE; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kf3J6PxE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 13655C4CEE6; Wed, 30 Oct 2024 06:33:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730270009; bh=SC0Xu24Wqh43ElDcUACTlpmVLeS1VgEZ9q2pTiK0tTQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=kf3J6PxEKPDD4Fz76JOnhxqOI1OG68PL1+OtmdWR48jgGSd4xHgBHoljIc2JAsvir 8ALulSMNeCtgUxLpj3RFMuxF5YjUa4CsJdCCmVsFZt9fgZcbRhs8Ds9j54DvyeP+Jp FtIowtsja5piCmhoXVWCOvFYvTRrksj6Wu9FkdpoXR81Uys+1rrtQYTFhb7VEcZdHL 5/8mFOvhAg94PcAOZ3mRzc2CGBm6mrUnhowYJiYSmmMEBDCoIqGA190Ur7tlze0iLA M+PDLRoO/3AumSvVPIr3eypPvsG3ggcpyPHnZINVicOJkee4aV3voJtSPYzhZqnKHD uFO6sA8QE4ycA== Message-ID: <419edf13-3f5e-4d30-90d8-88118f77f704@kernel.org> Date: Wed, 30 Oct 2024 07:33:24 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH tty-next v3 5/6] serial: 8250: Switch to nbcon console To: John Ogness , Greg Kroah-Hartman Cc: Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , Esben Haabendal , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Andy Shevchenko , Geert Uytterhoeven , Arnd Bergmann , =?UTF-8?Q?Uwe_Kleine-K=C3=B6nig?= , Tony Lindgren , Rengarajan S , Peter Collingbourne , Serge Semin , Lino Sanfilippo References: <20241025105728.602310-1-john.ogness@linutronix.de> <20241025105728.602310-6-john.ogness@linutronix.de> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; keydata= xsFNBE6S54YBEACzzjLwDUbU5elY4GTg/NdotjA0jyyJtYI86wdKraekbNE0bC4zV+ryvH4j rrcDwGs6tFVrAHvdHeIdI07s1iIx5R/ndcHwt4fvI8CL5PzPmn5J+h0WERR5rFprRh6axhOk rSD5CwQl19fm4AJCS6A9GJtOoiLpWn2/IbogPc71jQVrupZYYx51rAaHZ0D2KYK/uhfc6neJ i0WqPlbtIlIrpvWxckucNu6ZwXjFY0f3qIRg3Vqh5QxPkojGsq9tXVFVLEkSVz6FoqCHrUTx wr+aw6qqQVgvT/McQtsI0S66uIkQjzPUrgAEtWUv76rM4ekqL9stHyvTGw0Fjsualwb0Gwdx ReTZzMgheAyoy/umIOKrSEpWouVoBt5FFSZUyjuDdlPPYyPav+hpI6ggmCTld3u2hyiHji2H cDpcLM2LMhlHBipu80s9anNeZhCANDhbC5E+NZmuwgzHBcan8WC7xsPXPaiZSIm7TKaVoOcL 9tE5aN3jQmIlrT7ZUX52Ff/hSdx/JKDP3YMNtt4B0cH6ejIjtqTd+Ge8sSttsnNM0CQUkXps w98jwz+Lxw/bKMr3NSnnFpUZaxwji3BC9vYyxKMAwNelBCHEgS/OAa3EJoTfuYOK6wT6nadm YqYjwYbZE5V/SwzMbpWu7Jwlvuwyfo5mh7w5iMfnZE+vHFwp/wARAQABzSFKaXJpIFNsYWJ5 IDxqaXJpc2xhYnlAa2VybmVsLm9yZz7CwXcEEwEIACEFAlW3RUwCGwMFCwkIBwIGFQgJCgsC BBYCAwECHgECF4AACgkQvSWxBAa0cEnVTg//TQpdIAr8Tn0VAeUjdVIH9XCFw+cPSU+zMSCH eCZoA/N6gitEcnvHoFVVM7b3hK2HgoFUNbmYC0RdcSc80pOF5gCnACSP9XWHGWzeKCARRcQR 4s5YD8I4VV5hqXcKo2DFAtIOVbHDW+0okOzcecdasCakUTr7s2fXz97uuoc2gIBB7bmHUGAH XQXHvdnCLjDjR+eJN+zrtbqZKYSfj89s/ZHn5Slug6w8qOPT1sVNGG+eWPlc5s7XYhT9z66E l5C0rG35JE4PhC+tl7BaE5IwjJlBMHf/cMJxNHAYoQ1hWQCKOfMDQ6bsEr++kGUCbHkrEFwD UVA72iLnnnlZCMevwE4hc0zVhseWhPc/KMYObU1sDGqaCesRLkE3tiE7X2cikmj/qH0CoMWe gjnwnQ2qVJcaPSzJ4QITvchEQ+tbuVAyvn9H+9MkdT7b7b2OaqYsUP8rn/2k1Td5zknUz7iF oJ0Z9wPTl6tDfF8phaMIPISYrhceVOIoL+rWfaikhBulZTIT5ihieY9nQOw6vhOfWkYvv0Dl o4GRnb2ybPQpfEs7WtetOsUgiUbfljTgILFw3CsPW8JESOGQc0Pv8ieznIighqPPFz9g+zSu Ss/rpcsqag5n9rQp/H3WW5zKUpeYcKGaPDp/vSUovMcjp8USIhzBBrmI7UWAtuedG9prjqfO wU0ETpLnhgEQAM+cDWLL+Wvc9cLhA2OXZ/gMmu7NbYKjfth1UyOuBd5emIO+d4RfFM02XFTI t4MxwhAryhsKQQcA4iQNldkbyeviYrPKWjLTjRXT5cD2lpWzr+Jx7mX7InV5JOz1Qq+P+nJW YIBjUKhI03ux89p58CYil24Zpyn2F5cX7U+inY8lJIBwLPBnc9Z0An/DVnUOD+0wIcYVnZAK DiIXODkGqTg3fhZwbbi+KAhtHPFM2fGw2VTUf62IHzV+eBSnamzPOBc1XsJYKRo3FHNeLuS8 f4wUe7bWb9O66PPFK/RkeqNX6akkFBf9VfrZ1rTEKAyJ2uqf1EI1olYnENk4+00IBa+BavGQ 8UW9dGW3nbPrfuOV5UUvbnsSQwj67pSdrBQqilr5N/5H9z7VCDQ0dhuJNtvDSlTf2iUFBqgk 3smln31PUYiVPrMP0V4ja0i9qtO/TB01rTfTyXTRtqz53qO5dGsYiliJO5aUmh8swVpotgK4 /57h3zGsaXO9PGgnnAdqeKVITaFTLY1ISg+Ptb4KoliiOjrBMmQUSJVtkUXMrCMCeuPDGHo7 39Xc75lcHlGuM3yEB//htKjyprbLeLf1y4xPyTeeF5zg/0ztRZNKZicgEmxyUNBHHnBKHQxz 1j+mzH0HjZZtXjGu2KLJ18G07q0fpz2ZPk2D53Ww39VNI/J9ABEBAAHCwV8EGAECAAkFAk6S 54YCGwwACgkQvSWxBAa0cEk3tRAAgO+DFpbyIa4RlnfpcW17AfnpZi9VR5+zr496n2jH/1ld wRO/S+QNSA8qdABqMb9WI4BNaoANgcg0AS429Mq0taaWKkAjkkGAT7mD1Q5PiLr06Y/+Kzdr 90eUVneqM2TUQQbK+Kh7JwmGVrRGNqQrDk+gRNvKnGwFNeTkTKtJ0P8jYd7P1gZb9Fwj9YLx jhn/sVIhNmEBLBoI7PL+9fbILqJPHgAwW35rpnq4f/EYTykbk1sa13Tav6btJ+4QOgbcezWI wZ5w/JVfEJW9JXp3BFAVzRQ5nVrrLDAJZ8Y5ioWcm99JtSIIxXxt9FJaGc1Bgsi5K/+dyTKL wLMJgiBzbVx8G+fCJJ9YtlNOPWhbKPlrQ8+AY52Aagi9WNhe6XfJdh5g6ptiOILm330mkR4g W6nEgZVyIyTq3ekOuruftWL99qpP5zi+eNrMmLRQx9iecDNgFr342R9bTDlb1TLuRb+/tJ98 f/bIWIr0cqQmqQ33FgRhrG1+Xml6UXyJ2jExmlO8JljuOGeXYh6ZkIEyzqzffzBLXZCujlYQ DFXpyMNVJ2ZwPmX2mWEoYuaBU0JN7wM+/zWgOf2zRwhEuD3A2cO2PxoiIfyUEfB9SSmffaK/ S4xXoB6wvGENZ85Hg37C7WDNdaAt6Xh2uQIly5grkgvWppkNy4ZHxE+jeNsU7tg= In-Reply-To: <20241025105728.602310-6-john.ogness@linutronix.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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 > --- > 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