Messages in this thread Patch in this message | | | From | Masahiro Yamada <> | Subject | [PATCH v2 2/2] serial: earlycon: allow to specify uartclk in earlycon kernel-parameter | Date | Tue, 20 Oct 2015 12:36:29 +0900 |
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The input clock frequency varies from device to device, but the earlycon uses the fixed frequency (BASE_BAUD * 16). It makes impossible to set the correct divisor to the register.
This commit allows to specify the input clock frequency from the kernel-parameter.
[Example]
earlycon=uart8250,mmio32,0x43fb0000,115200,12288000
The input clock frequency (12288000, in this case) should be specified after the baudrate. If not specified, the default (BASE_BAUD * 16) is used.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> ---
Changes in v2: None
drivers/tty/serial/earlycon.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c index 07f7393..8030765 100644 --- a/drivers/tty/serial/earlycon.c +++ b/drivers/tty/serial/earlycon.c @@ -95,6 +95,13 @@ static int __init parse_options(struct earlycon_device *device, char *options) length = min(strcspn(options, " ") + 1, (size_t)(sizeof(device->options))); strlcpy(device->options, options, length); + options = strchr(options, ','); + if (options) { + options++; + port->uartclk = simple_strtoul(options, NULL, 0); + } + if (!port->uartclk) + port->uartclk = BASE_BAUD * 16; } if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM16 || @@ -122,7 +129,6 @@ static int __init register_earlycon(char *buf, const struct earlycon_id *match) if (buf && !parse_options(&early_console_dev, buf)) buf = NULL; - port->uartclk = BASE_BAUD * 16; if (port->mapbase) port->membase = earlycon_map(port->mapbase, 64); -- 1.9.1
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