Some platforms, namely AMD Picasso, use non standard uart clocks (48M),
witch makes it impossible to use with earlycon.
Let the user select its own frequency.
Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index a465d5242774..9efb6c3b0486 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1182,10 +1182,10 @@
specified, the serial port must already be setup and
configured.
- uart[8250],io,<addr>[,options]
- uart[8250],mmio,<addr>[,options]
- uart[8250],mmio32,<addr>[,options]
- uart[8250],mmio32be,<addr>[,options]
+ uart[8250],io,<addr>[,options[,uartclk]]
+ uart[8250],mmio,<addr>[,options[,uartclk]]
+ uart[8250],mmio32,<addr>[,options[,uartclk]]
+ uart[8250],mmio32be,<addr>[,options[,uartclk]]
uart[8250],0x<addr>[,options]
Start an early, polled-mode console on the 8250/16550
UART at the specified I/O port or MMIO address.
@@ -1194,7 +1194,9 @@
If none of [io|mmio|mmio32|mmio32be], <addr> is assumed
to be equivalent to 'mmio'. 'options' are specified
in the same format described for "console=ttyS<n>"; if
- unspecified, the h/w is not initialized.
+ unspecified, the h/w is not initialized. 'uartclk' is
+ the uart clock frequency; if unspecified, it is set
+ to 'BASE_BAUD' * 16.
pl011,<addr>
pl011,mmio32,<addr>
diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index 5b73da9487b1..2db92d36351b 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -120,9 +120,15 @@ static int __init parse_options(struct earlycon_device *device, char *options)
}
if (options) {
+ char *uartclk;
+
if (kstrtouint(options, 0, &device->baud) < 0)
pr_warn("[%s] unsupported earlycon baud rate option\n",
options);
+ uartclk = strchr(options, ',');
+ if (uartclk && kstrtouint(uartclk, 0, &port->uartclk) < 0)
+ pr_warn("[%s] unsupported earlycon uart clkrate option\n",
+ options);
length = min(strcspn(options, " ") + 1,
(size_t)(sizeof(device->options)));
strscpy(device->options, options, length);
@@ -141,7 +147,8 @@ static int __init register_earlycon(char *buf, const struct earlycon_id *match)
buf = NULL;
spin_lock_init(&port->lock);
- port->uartclk = BASE_BAUD * 16;
+ if (!port->uartclk)
+ port->uartclk = BASE_BAUD * 16;
if (port->mapbase)
port->membase = earlycon_map(port->mapbase, 64);
--
b4 0.11.0-dev-d93f8
