Commit 70acca67 authored by Esben Haabendal's avatar Esben Haabendal Committed by Greg Kroah-Hartman
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serial: imx: Switch to nbcon console 



Implements the necessary callbacks to switch the imx console driver to
perform as an nbcon console.

Add implementations for the nbcon consoles (write_atomic, write_thread,
driver_enter, driver_exit) and add CON_NBCON to the initial flags.

The legacy code is kept in order to easily switch back to legacy mode
by defining CONFIG_SERIAL_IMX_LEGACY_CONSOLE.

Signed-off-by: default avatarEsben Haabendal <esben@geanix.com>
Link: https://lore.kernel.org/r/20240913-serial-imx-nbcon-v3-1-4c627302335b@geanix.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent fd29e1e4

drivers/tty/serial/imx.c

+101 −19
Original line number Diff line number Diff line
@@ -230,6 +230,8 @@ struct imx_port { 
	unsigned int            saved_reg[10];

	bool			context_saved;



	bool			last_putchar_was_newline;



	enum imx_tx_state	tx_state;

	struct hrtimer		trigger_start_tx;

	struct hrtimer		trigger_stop_tx;
@@ -2064,26 +2066,75 @@ static void imx_uart_console_putchar(struct uart_port *port, unsigned char ch) 
		barrier();



	imx_uart_writel(sport, ch, URTX0);



	sport->last_putchar_was_newline = (ch == '\n');

}



static void imx_uart_console_device_lock(struct console *co, unsigned long *flags)

{

	struct uart_port *up = &imx_uart_ports[co->index]->port;



	return __uart_port_lock_irqsave(up, flags);

}



static void imx_uart_console_device_unlock(struct console *co, unsigned long flags)

{

	struct uart_port *up = &imx_uart_ports[co->index]->port;



	return __uart_port_unlock_irqrestore(up, flags);

}



static void imx_uart_console_write_atomic(struct console *co,

					  struct nbcon_write_context *wctxt)

{

	struct imx_port *sport = imx_uart_ports[co->index];

	struct uart_port *port = &sport->port;

	struct imx_port_ucrs old_ucr;

	unsigned int ucr1, usr2;



	if (!nbcon_enter_unsafe(wctxt))

		return;



	/*

 * Interrupts are disabled on entering

	 *	First, save UCR1/2/3 and then disable interrupts

	 */

static void

imx_uart_console_write(struct console *co, const char *s, unsigned int count)

	imx_uart_ucrs_save(sport, &old_ucr);

	ucr1 = old_ucr.ucr1;



	if (imx_uart_is_imx1(sport))

		ucr1 |= IMX1_UCR1_UARTCLKEN;

	ucr1 |= UCR1_UARTEN;

	ucr1 &= ~(UCR1_TRDYEN | UCR1_RRDYEN | UCR1_RTSDEN);



	imx_uart_writel(sport, ucr1, UCR1);

	imx_uart_writel(sport, old_ucr.ucr2 | UCR2_TXEN, UCR2);



	if (!sport->last_putchar_was_newline)

		uart_console_write(port, "\n", 1, imx_uart_console_putchar);

	uart_console_write(port, wctxt->outbuf, wctxt->len,

			   imx_uart_console_putchar);



	/*

	 *	Finally, wait for transmitter to become empty

	 *	and restore UCR1/2/3

	 */

	read_poll_timeout_atomic(imx_uart_readl, usr2, usr2 & USR2_TXDC,

				 0, USEC_PER_SEC, false, sport, USR2);

	imx_uart_ucrs_restore(sport, &old_ucr);



	nbcon_exit_unsafe(wctxt);

}



static void imx_uart_console_write_thread(struct console *co,

					  struct nbcon_write_context *wctxt)

{

	struct imx_port *sport = imx_uart_ports[co->index];

	struct uart_port *port = &sport->port;

	struct imx_port_ucrs old_ucr;

	unsigned long flags;

	unsigned int ucr1, usr2;

	int locked = 1;



	if (sport->port.sysrq)

		locked = 0;

	else if (oops_in_progress)

		locked = uart_port_trylock_irqsave(&sport->port, &flags);

	else

		uart_port_lock_irqsave(&sport->port, &flags);

	if (!nbcon_enter_unsafe(wctxt))

		return;



	/*

	 *	First, save UCR1/2/3 and then disable interrupts
@@ -2097,21 +2148,47 @@ imx_uart_console_write(struct console *co, const char *s, unsigned int count) 
	ucr1 &= ~(UCR1_TRDYEN | UCR1_RRDYEN | UCR1_RTSDEN);



	imx_uart_writel(sport, ucr1, UCR1);



	imx_uart_writel(sport, old_ucr.ucr2 | UCR2_TXEN, UCR2);



	uart_console_write(&sport->port, s, count, imx_uart_console_putchar);

	if (nbcon_exit_unsafe(wctxt)) {

		int len = READ_ONCE(wctxt->len);

		int i;



		/*

		 * Write out the message. Toggle unsafe for each byte in order

		 * to give another (higher priority) context the opportunity

		 * for a friendly takeover. If such a takeover occurs, this

		 * context must reacquire ownership in order to perform final

		 * actions (such as re-enabling the interrupts).

		 *

		 * IMPORTANT: wctxt->outbuf and wctxt->len are no longer valid

		 *	      after a reacquire so writing the message must be

		 *	      aborted.

		 */

		for (i = 0; i < len; i++) {

			if (!nbcon_enter_unsafe(wctxt))

				break;



			uart_console_write(port, wctxt->outbuf + i, 1,

					   imx_uart_console_putchar);



			if (!nbcon_exit_unsafe(wctxt))

				break;

		}

	}



	while (!nbcon_enter_unsafe(wctxt))

		nbcon_reacquire_nobuf(wctxt);



	/*

	 *	Finally, wait for transmitter to become empty

	 *	and restore UCR1/2/3

	 */

	read_poll_timeout_atomic(imx_uart_readl, usr2, usr2 & USR2_TXDC,

	read_poll_timeout(imx_uart_readl, usr2, usr2 & USR2_TXDC,

			  0, USEC_PER_SEC, false, sport, USR2);

	imx_uart_ucrs_restore(sport, &old_ucr);



	if (locked)

		uart_port_unlock_irqrestore(&sport->port, flags);

	nbcon_exit_unsafe(wctxt);

}



/*
@@ -2203,6 +2280,8 @@ imx_uart_console_setup(struct console *co, char *options) 
	if (retval)

		goto error_console;



	sport->last_putchar_was_newline = true;



	if (options)

		uart_parse_options(options, &baud, &parity, &bits, &flow);

	else
@@ -2239,11 +2318,14 @@ imx_uart_console_exit(struct console *co) 
static struct uart_driver imx_uart_uart_driver;

static struct console imx_uart_console = {

	.name		= DEV_NAME,

	.write		= imx_uart_console_write,

	.write_atomic	= imx_uart_console_write_atomic,

	.write_thread	= imx_uart_console_write_thread,

	.device_lock	= imx_uart_console_device_lock,

	.device_unlock	= imx_uart_console_device_unlock,

	.flags		= CON_PRINTBUFFER | CON_NBCON,

	.device		= uart_console_device,

	.setup		= imx_uart_console_setup,

	.exit		= imx_uart_console_exit,

	.flags		= CON_PRINTBUFFER,

	.index		= -1,

	.data		= &imx_uart_uart_driver,

};