[PATCH v2 1/4] tty: serial: Add 8250 earlycon to support noinit option
From: Peter Hurley <hidden>
Date: 2015-02-01 16:27:39
Also in:
linux-devicetree, linux-serial, lkml
Hi Eddie, On 01/12/2015 08:08 AM, Eddie Huang wrote:
Add earlycon support not only baudrate option, but also add noinit option. If use noinit option, 8250 earlycon will not init serial hardware and use loader setting.
I see this went into Greg's tty-testing branch.
The only point of this is to not program the divisor, right?
I ask because early_serial8250_setup() could already handle this without
extra options by simply not doing divisor programming if no baud option is
present.
And this blows up if the optional console= form is used:
console=uart,mmio32,<addr>,noinit
because the ttyS console will expect line settings for console match.
Regards,
Peter Hurley
quoted hunk ↗ jump to hunk
Signed-off-by: Eddie Huang <eddie.huang@mediatek.com> --- drivers/tty/serial/8250/8250_early.c | 7 ++++--- drivers/tty/serial/earlycon.c | 17 ++++++++++++----- include/linux/serial_8250.h | 2 ++ include/linux/serial_core.h | 1 + 4 files changed, 19 insertions(+), 8 deletions(-)diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c index 4858b8a..a13d757 100644 --- a/drivers/tty/serial/8250/8250_early.c +++ b/drivers/tty/serial/8250/8250_early.c@@ -138,19 +138,20 @@ static void __init init_port(struct earlycon_device *device) serial8250_early_out(port, UART_LCR, c & ~UART_LCR_DLAB); } -static int __init early_serial8250_setup(struct earlycon_device *device, +int __init early_serial8250_setup(struct earlycon_device *device, const char *options) { if (!(device->port.membase || device->port.iobase)) return 0; - if (!device->baud) { + if (!device->baud && !device->noinit) { device->baud = probe_baud(&device->port); snprintf(device->options, sizeof(device->options), "%u", device->baud); } - init_port(device); + if (!device->noinit) + init_port(device); early_device = device; device->con->write = early_serial8250_write;diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c index 64fe25a..4891251 100644 --- a/drivers/tty/serial/earlycon.c +++ b/drivers/tty/serial/earlycon.c@@ -58,7 +58,7 @@ static int __init parse_options(struct earlycon_device *device, char *options) { struct uart_port *port = &device->port; - int mmio, mmio32, length; + int noinit, mmio, mmio32, length; unsigned long addr; if (!options)@@ -92,10 +92,17 @@ static int __init parse_options(struct earlycon_device *device, options = strchr(options, ','); if (options) { options++; - device->baud = simple_strtoul(options, NULL, 0); - length = min(strcspn(options, " ") + 1, - (size_t)(sizeof(device->options))); - strlcpy(device->options, options, length); + noinit = !strncmp(options, "noinit", 6); + if (noinit) { + device->noinit = noinit; + strlcpy(device->options, options, 6); + device->options[6] = '\0'; + } else { + device->baud = simple_strtoul(options, NULL, 0); + length = min(strcspn(options, " ") + 1, + (size_t)(sizeof(device->options))); + strlcpy(device->options, options, length); + } } if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM32)diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h index e02acf0..0e26eec 100644 --- a/include/linux/serial_8250.h +++ b/include/linux/serial_8250.h@@ -119,6 +119,8 @@ extern int serial8250_find_port(struct uart_port *p); extern int serial8250_find_port_for_earlycon(void); extern unsigned int serial8250_early_in(struct uart_port *port, int offset); extern void serial8250_early_out(struct uart_port *port, int offset, int value); +extern int early_serial8250_setup(struct earlycon_device *device, + const char *options); extern int setup_early_serial8250_console(char *cmdline); extern void serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, struct ktermios *old);diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index 057038c..72c6698 100644 --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h@@ -326,6 +326,7 @@ struct earlycon_device { struct uart_port port; char options[16]; /* e.g., 115200n8 */ unsigned int baud; + int noinit; }; int setup_earlycon(char *buf, const char *match, int (*setup)(struct earlycon_device *, const char *));