[yocto] [PATCH 10/11] pch_uart: Add user_uartclk parameter

[Darren Hart]

For cases where boards with non-default clocks are not yet added to the kernel
or when the clock varies across hardware revisions, it is useful to be
able to specify the UART clock on the kernel command line.

Add the user_uartclk parameter and prefer it, if set, to the default and
board specific UART clock settings. Specify user_uartclock on the command-line
with "pch_uart.user_uartclk=48000000".

Signed-off-by: Darren Hart <dvhart at linux.intel.com>
CC: Tomoya MORINAGA <tomoya.rohm at gmail.com>
CC: Feng Tang <feng.tang at intel.com>
CC: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
CC: Alan Cox <alan at linux.intel.com>
CC: linux-serial at vger.kernel.org
---
 drivers/tty/serial/pch_uart.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index 1706169..2233e31 100644
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -290,6 +290,7 @@ static struct pch_uart_driver_data drv_dat[] = {
 static struct eg20t_port *pch_uart_ports[PCH_UART_NR];
 #endif
 static unsigned int default_baud = 9600;
+static unsigned int user_uartclk = 0;
 static const int trigger_level_256[4] = { 1, 64, 128, 224 };
 static const int trigger_level_64[4] = { 1, 16, 32, 56 };
 static const int trigger_level_16[4] = { 1, 4, 8, 14 };
@@ -300,6 +301,9 @@ static int pch_uart_get_uartclk(void)
 {
 	const char *cmp;
 
+	if (user_uartclk)
+		return user_uartclk;
+
 	cmp = dmi_get_system_info(DMI_BOARD_NAME);
 	if (cmp && strstr(cmp, "CM-iTC"))
 		return CMITC_UARTCLK;
@@ -1799,3 +1803,4 @@ module_exit(pch_uart_module_exit);
 MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("Intel EG20T PCH UART PCI Driver");
 module_param(default_baud, uint, S_IRUGO);
+module_param(user_uartclk, uint, S_IRUGO);
-- 
1.7.6.5