On Sun, Mar 1, 2015 at 10:05 AM, Peter Hurley <peter@xxxxxxxxxxxxxxxxxx> wrote: > Changes from v1: > * rebased on and requires "console: Fix console name size mismatch" I plan to pick this one up for 4.0 because I need it for "of: Fix premature bootconsole disable with 'stdout-path'". > Hi Greg & Andrew, > > This patch series implements: > 1. console-definable (aka extensible) matching > 2. generic earlycon-to-console handoff via extensible matching > 3. arch/prom support for direct earlycon > > > Extensible console matching > > Extensible console matching enables the console itself to define the > conditions for a "command line" match. This mimics the design of > device matching in the driver model. Two important use-cases which this > feature enables are generic earlycon-to-console handoff and support > for driver migration. > > Earlycon-to-console handoff was implemented in 2007. Console command > lines of the form: > console=uart,io,0x3f8,115200n8 > start an earlycon and later allow the 8250 driver console to takeover. > Unfortunately this implementation requires direct coupling between > the earlycon and the console and is facilitated by ugly hacks like > editing the console command line in-place. > > Extensible console matching allows the 8250 driver to directly match > that console command line instead, and enables other serial drivers > to trivially support console handoff themselves. > > In addition, extensible console matching allows a new driver to > provide support for a different driver's console. This requirement > stems from needing to minimize breakage when migrating serial drivers. > Since many devices are based on the original 8250/16550 designs > but sometimes have features incompatible with the existing 8250 driver > support, the initial driver is often standalone. When/if the standalone > driver is migrated to the 8250 driver, the problem of console names in > the command line remains. Extensible console matching enables a simple > migration path. > > > Direct earlycon > > This feature enables arches and proms to start an earlycon directly, > rather than requiring an "earlycon=" command line parameter. > Devicetree can already do this via the 'linux,stdout-path' property, > but arch and prom code requires direct coupling to the serial driver. > > This support is implemented by judicious refactoring and the same > construct that devicetree and early_param use: a link table containing > the necessary information (name and setup() function) to find and > bind the appropriate earlycon "driver". > > > NB: I combined these two features in this series because their > implementations heavily overlap in the same source files. > > Regards, > > Peter Hurley (13): > serial: earlycon: Refactor parse_options into serial core > console: Preserve index after console setup() > console: Add extensible console matching > serial: core: Fix kernel doc for uart_console_write() > serial: 8250_early: Remove early_device variable > serial: earlycon: Move ->uartclk initialize > serial: 8250_early: Assume uart already initialized if no baud option > serial: 8250_early: Fix setup() error code > serial: earlycon: Ignore parse_options() error code > serial: earlycon: Allow earlycon params with name only > serial: earlycon: Refactor earlycon registration > serial: earlycon: Enable earlycon without command line param > serial: 8250_early: Remove setup_early_serial8250_console() > > arch/mips/mti-malta/malta-init.c | 4 +- > drivers/firmware/pcdp.c | 4 +- > drivers/tty/serial/8250/8250_core.c | 64 ++++++++++++---- > drivers/tty/serial/8250/8250_early.c | 51 +++---------- > drivers/tty/serial/earlycon.c | 140 ++++++++++++++++++++++++----------- > drivers/tty/serial/serial_core.c | 48 +++++++++++- > include/asm-generic/vmlinux.lds.h | 9 +++ > include/linux/console.h | 3 +- > include/linux/serial_8250.h | 3 - > include/linux/serial_core.h | 21 ++++-- > kernel/printk/printk.c | 53 +++++-------- > 11 files changed, 246 insertions(+), 154 deletions(-) For the series: Acked-by: Rob Herring <robh@xxxxxxxxxx> > > -- > 2.3.0 > -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
