[PATCH 6/8] tty/serial: pl011: add generic earlycon support
From: Rob Herring <hidden>
Date: 2014-03-21 21:11:02
Also in:
linux-serial, lkml
Subsystem:
arm primecell uart pl010 and pl011 drivers, documentation, the rest, tty layer and serial drivers · Maintainers:
Russell King, Jonathan Corbet, Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
From: Rob Herring <robh@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 <robh@kernel.org> Cc: Russell King <redacted> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jiri Slaby <redacted> --- Documentation/kernel-parameters.txt | 5 +++-- drivers/tty/serial/amba-pl011.c | 30 +++++++++++++++++++++++++++++- 2 files changed, 32 insertions(+), 3 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 5ce8b7a..81bdd52 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt@@ -887,8 +887,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. uart[8250],io,<addr>[,options] uart[8250],mmio,<addr>[,options] uart[8250],mmio32,<addr>[,options] - Start an early, polled-mode console on the 8250/16550 - UART at the specified I/O port or MMIO address. + pl011,<addr> + Start an early, polled-mode console on a serial port + at the specified I/O port or MMIO address. 8250 MMIO inter-register address stride is either 8-bit (mmio) or 32-bit (mmio32). The options are the same as for ttyS, above.
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
--
1.8.3.2