[PATCH 3/5] 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@xxxxxxxxxxxxxxx>
CC: Tomoya MORINAGA <tomoya.rohm@xxxxxxxxx>
CC: Feng Tang <feng.tang@xxxxxxxxx>
CC: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
CC: Alan Cox <alan@xxxxxxxxxxxxxxx>
CC: linux-serial@xxxxxxxxxxxxxxx
---
 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 88a1be0..46f6fbf 100644
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -295,6 +295,7 @@ 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 };
@@ -372,6 +373,9 @@ 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;
@@ -1860,3 +1864,4 @@ 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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/