From: Rob Herring <r...@kernel.org>
Add earlycon support for the pl011 serial port. This allows enabling
the pl011 for console when early_params are processed. This is based
on the arm64 earlyprintk support and is intended to replace it.
Signed-off-by: Rob Herring <r...@kernel.org>
Cc: Russell King <li...@arm.linux.org.uk>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Cc: Jiri Slaby <jsl...@suse.cz>
---
v2:
- Rework the kernel-parameters.txt description
Documentation/kernel-parameters.txt | 7 +++++++
drivers/tty/serial/Kconfig | 1 +
drivers/tty/serial/amba-pl011.c | 30 +++++++++++++++++++++++++++++-
3 files changed, 37 insertions(+), 1 deletion(-)
diff --git a/Documentation/kernel-parameters.txt
b/Documentation/kernel-parameters.txt
index 03e50b4..15b5fcca 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -890,6 +890,7 @@ bytes respectively. Such letter suffixes can also be
entirely omitted.
which are not unmapped.
earlycon= [KNL] Output early console device and options.
+
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]
uart[8250],mmio32,<addr>[,options]
@@ -899,6 +900,12 @@ bytes respectively. Such letter suffixes can also be
entirely omitted.
(mmio) or 32-bit (mmio32).
The options are the same as for ttyS, above.
+ pl011,<addr>
+ Start an early, polled-mode console on a pl011 serial
+ port at the specified address. The pl011 serial port
+ must already be setup and configured. Options are not
+ yet supported.
+
earlyprintk= [X86,SH,BLACKFIN,ARM]
earlyprintk=vga
earlyprintk=efi
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 3b7c19b..b1b23c2 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -60,6 +60,7 @@ config SERIAL_AMBA_PL011_CONSOLE
bool "Support for console on AMBA serial port"
depends on SERIAL_AMBA_PL011=y
select SERIAL_CORE_CONSOLE
+ select SERIAL_EARLYCON
---help---
Say Y here if you wish to use an AMBA PrimeCell UART as the system
console (the system console is the device which receives all kernel
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index d4eda24..4227c0a 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -303,7 +303,7 @@ static void pl011_dma_probe_initcall(struct device *dev,
struct uart_amba_port *
/* Optionally make use of an RX channel as well */
chan = dma_request_slave_channel(dev, "rx");
-
+
if (!chan && plat->dma_rx_param) {
chan = dma_request_channel(mask, plat->dma_filter,
plat->dma_rx_param);
@@ -2045,6 +2045,34 @@ static struct console amba_console = {
};
#define AMBA_CONSOLE (&amba_console)
+
+static void pl011_putc(struct uart_port *port, int c)
+{
+ while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
+ ;
+ writeb(c, port->membase + UART01x_DR);
+ while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY)
+ ;
+}
+
+static void pl011_early_write(struct console *con, const char *s, unsigned n)
+{
+ struct earlycon_device *dev = con->data;
+
+ uart_console_write(&dev->port, s, n, pl011_putc);
+}
+
+static int __init pl011_early_console_setup(struct earlycon_device *device,
+ const char *opt)
+{
+ if (!device->port.membase)
+ return -ENODEV;
+
+ device->con->write = pl011_early_write;
+ return 0;
+}
+EARLYCON_DECLARE(pl011, pl011_early_console_setup);
+
#else
#define AMBA_CONSOLE NULL
#endif
--
1.9.1
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