Re: [PATCH v3] tty: serial: meson: Implement earlycon support

[Carlo Caione]

On Wed, Mar 2, 2016 at 3:49 AM, Andreas Färber  wrote:
> Split off the bulk of the existing meson_serial_console_write()
> implementation into meson_serial_port_write() for implementing
> meson_serial_early_console_write().
>
> Use "meson" as the earlycon driver name, courtesy of Nicolas.
>
> Signed-off-by: Nicolas Saenz Julienne 
> Signed-off-by: Andreas Färber 

Acked-by: Carlo Caione 

Thanks,

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Carlo Caione
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[PATCH v3] tty: serial: meson: Implement earlycon support

[Andreas Färber]

Split off the bulk of the existing meson_serial_console_write()
implementation into meson_serial_port_write() for implementing
meson_serial_early_console_write().

Use "meson" as the earlycon driver name, courtesy of Nicolas.

Signed-off-by: Nicolas Saenz Julienne 
Signed-off-by: Andreas Färber 
---
 v2 -> v3:
 * Rename from "meson_serial" to just "meson" (Nicolas)
 
 v1 -> v2:
 * Implement meson_serial_early_console_write() instead of reusing
   meson_serial_console_write() (Peter)
 
 Documentation/kernel-parameters.txt |  6 ++
 drivers/tty/serial/meson_uart.c | 42 ++---
 2 files changed, 41 insertions(+), 7 deletions(-)

diff --git a/Documentation/kernel-parameters.txt 
b/Documentation/kernel-parameters.txt
index e0a21e4556a6..a7c1377fd80f 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1039,6 +1039,12 @@ bytes respectively. Such letter suffixes can also be 
entirely omitted.
the driver will use only 32-bit accessors to read/write
the device registers.
 
+   meson,
+   Start an early, polled-mode console on a meson serial
+   port at the specified address. The serial port must
+   already be setup and configured. Options are not yet
+   supported.
+
msm_serial,
Start an early, polled-mode console on an msm serial
port at the specified address. The serial port
diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
index 024445aa0521..6aea0f4a9165 100644
--- a/drivers/tty/serial/meson_uart.c
+++ b/drivers/tty/serial/meson_uart.c
@@ -481,18 +481,13 @@ static void meson_console_putchar(struct uart_port *port, 
int ch)
writel(ch, port->membase + AML_UART_WFIFO);
 }
 
-static void meson_serial_console_write(struct console *co, const char *s,
-  u_int count)
+static void meson_serial_port_write(struct uart_port *port, const char *s,
+   u_int count)
 {
-   struct uart_port *port;
unsigned long flags;
int locked;
u32 val, tmp;
 
-   port = meson_ports[co->index];
-   if (!port)
-   return;
-
local_irq_save(flags);
if (port->sysrq) {
locked = 0;
@@ -516,6 +511,18 @@ static void meson_serial_console_write(struct console *co, 
const char *s,
local_irq_restore(flags);
 }
 
+static void meson_serial_console_write(struct console *co, const char *s,
+  u_int count)
+{
+   struct uart_port *port;
+
+   port = meson_ports[co->index];
+   if (!port)
+   return;
+
+   meson_serial_port_write(port, s, count);
+}
+
 static int meson_serial_console_setup(struct console *co, char *options)
 {
struct uart_port *port;
@@ -554,6 +561,27 @@ static int __init meson_serial_console_init(void)
 }
 console_initcall(meson_serial_console_init);
 
+static void meson_serial_early_console_write(struct console *co,
+const char *s,
+u_int count)
+{
+   struct earlycon_device *dev = co->data;
+
+   meson_serial_port_write(>port, s, count);
+}
+
+static int __init
+meson_serial_early_console_setup(struct earlycon_device *device, const char 
*opt)
+{
+   if (!device->port.membase)
+   return -ENODEV;
+
+   device->con->write = meson_serial_early_console_write;
+   return 0;
+}
+OF_EARLYCON_DECLARE(meson, "amlogic,meson-uart",
+   meson_serial_early_console_setup);
+
 #define MESON_SERIAL_CONSOLE   (_serial_console)
 #else
 #define MESON_SERIAL_CONSOLE   NULL
-- 
2.6.2

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