[PATCH v2 2/3] serial: 8250_early: prepare for dynamic BASE_BAUD

From: Vineet Gupta
Date: Mon Jan 05 2015 - 06:31:14 EST


BASE_BAUD is pain in neck for multi-platform support as it hard codes at
build time the clk value for early uart.

Mitigate this by allowing arches/platforms to provide their own version
which can do dynamic setup based on DT values etc (see next patch for
usage)

This was needed for ARC SDP platforms based on 2 different FPGA flows, each
with a different UART clk value.

Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Jiri Slaby <jslaby@xxxxxxx>
Cc: linux-serial@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: Rob Herring <robh@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
---
drivers/tty/serial/earlycon.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index 64fe25a4285c..bfd3537739e0 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -54,6 +54,15 @@ static void __iomem * __init earlycon_map(unsigned long paddr, size_t size)
return base;
}

+unsigned int __weak __init earlycon_base_baud(char *options)
+{
+#ifdef BASE_BAUD
+ return BASE_BAUD;
+#else
+ return 1843200/16; /* x86 early console */
+#endif
+}
+
static int __init parse_options(struct earlycon_device *device,
char *options)
{
@@ -87,7 +96,7 @@ static int __init parse_options(struct earlycon_device *device,
return -EINVAL;
}

- port->uartclk = BASE_BAUD * 16;
+ port->uartclk = earlycon_base_baud(options) * 16;

options = strchr(options, ',');
if (options) {
@@ -156,7 +165,7 @@ int __init of_setup_earlycon(unsigned long addr,

port->iotype = UPIO_MEM;
port->mapbase = addr;
- port->uartclk = BASE_BAUD * 16;
+ port->uartclk = earlycon_base_baud(NULL) * 16;
port->membase = earlycon_map(addr, SZ_4K);

early_console_dev.con->data = &early_console_dev;
--
1.9.1

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