serial: amba-pl011: Support kgdboc_earlycon (195867ff) · Commits · 戴 / test

Implement the read() function in the early console driver. With recently added kgdboc_earlycon feature, this allows you to use kgdb to debug fairly early into the system boot. We only bother implementing this if polling is enabled since kgdb can't be enabled without that. Signed-off-by:

Sumit Garg <sumit.garg@linaro.org> Reviewed-by:

Douglas Anderson <dianders@chromium.org> Reviewed-by:

Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by:

Douglas Anderson <dianders@chromium.org> Link: https://lore.kernel.org/r/20200507130644.v4.12.I8ee0811f0e0816dd8bfe7f2f5540b3dba074fae8@changeid Signed-off-by:

Daniel Thompson <daniel.thompson@linaro.org>

drivers/tty/serial/amba-pl011.c

+32 −0

Original line number	Diff line number	Diff line
		@@ -2435,6 +2435,37 @@ static void pl011_early_write(struct console con, const char s, unsigned n)
		uart_console_write(&dev->port, s, n, pl011_putc);
		}

		#ifdef CONFIG_CONSOLE_POLL
		static int pl011_getc(struct uart_port *port)
		{
		if (readl(port->membase + UART01x_FR) & UART01x_FR_RXFE)
		return NO_POLL_CHAR;

		if (port->iotype == UPIO_MEM32)
		return readl(port->membase + UART01x_DR);
		else
		return readb(port->membase + UART01x_DR);
		}

		static int pl011_early_read(struct console con, char s, unsigned int n)
		{
		struct earlycon_device *dev = con->data;
		int ch, num_read = 0;

		while (num_read < n) {
		ch = pl011_getc(&dev->port);
		if (ch == NO_POLL_CHAR)
		break;

		s[num_read++] = ch;
		}

		return num_read;
		}
		#else
		#define pl011_early_read NULL
		#endif

		/*
		* On non-ACPI systems, earlycon is enabled by specifying
		* "earlycon=pl011,<address>" on the kernel command line.
		@@ -2454,6 +2485,7 @@ static int __init pl011_early_console_setup(struct earlycon_device *device,
		return -ENODEV;

		device->con->write = pl011_early_write;
		device->con->read = pl011_early_read;

		return 0;
		}

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