kernel/linux.git/drivers/tty/serial/earlycon.c, branch linux-4.4.y

serial: earlycon: Add missing spinlock initialization

2015-12-13T07:05:28+00:00

If an earlycon console driver needs to acquire the uart_port.lock spinlock for serial console output, and CONFIG_DEBUG_SPINLOCK=y: BUG: spinlock bad magic on CPU#0, swapper/0 lock: sci_ports+0x0/0x3480, .magic: 00000000, .owner: /-1, .owner_cpu: 0 CPU: 0 PID: 0 Comm: swapper Not tainted 4.4.0-rc2-koelsch-g62ea5edf143bb1d0-dirty #2083 Hardware name: Generic R8A7791 (Flattened Device Tree) [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (dump_stack+0x70/0x8c) [] (dump_stack) from [] (do_raw_spin_lock+0x20/0x190) [] (do_raw_spin_lock) from [] (serial_console_write+0x4c/0x130) [] (serial_console_write) from [] (call_console_drivers.constprop.13+0xc8/0xec) [] (call_console_drivers.constprop.13) from [] (console_unlock+0x354/0x440) [] (console_unlock) from [] (register_console+0x2a0/0x394) [] (register_console) from [] (of_setup_earlycon+0x90/0xa4) [] (of_setup_earlycon) from [] (setup_of_earlycon+0x118/0x13c) [] (setup_of_earlycon) from [] (do_early_param+0x64/0xb4) [] (do_early_param) from [] (parse_args+0x254/0x350) [] (parse_args) from [] (parse_early_options+0x2c/0x3c) [] (parse_early_options) from [] (parse_early_param+0x2c/0x40) [] (parse_early_param) from [] (setup_arch+0x520/0xaf0) [] (setup_arch) from [] (start_kernel+0x94/0x370) [] (start_kernel) from [<40008090>] (0x40008090) Initialize the spinlock in of_setup_earlycon() and register_earlycon(), to fix this for both DT-based and legacy earlycon. If the driver would reinitialize the spinlock again, this is harmless, as it's allowed to reinitialize an unlocked spinlock. Alternatives are: - Drivers having an early_serial_console_write() that only performs the core functionality of serial_console_write(), without acquiring the lock (which may be unsafe, depending on the hardware), - Drivers initializing the spinlock in their private earlycon setup functions. As uart_port is owned by generic serial_core, and uart_port.lock is initialized by uart_add_one_port() for the normal case, this can better be handled in the earlycon core. Signed-off-by: Geert Uytterhoeven Reviewed-by: Peter Hurley Reported-by: Bjorn Andersson Signed-off-by: Greg Kroah-Hartman

serial: earlycon: Add support for big-endian MMIO accesses

2015-05-31T21:55:12+00:00

Support command line parameters of the form: earlycon=,io|mmio|mmio32|mmio32be,, This commit seem to be needed even after commit: serial: 8250: Add support for big-endian MMIO accesses c627f2ceb692e8a9358b64ac2d139314e7bb0d17 Signed-off-by: Noam Camus Signed-off-by: Greg Kroah-Hartman

earlycon: Revert log warnings

2015-05-08T12:20:50+00:00

Log warnings meant to help diagnose problems setting up earlycon are reporting false positives for 'console='. Revert to the previous behavior which reported nothing. Cc: Maciej W. Rozycki Cc: Robert Schwebel Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

serial: earlycon: Enable earlycon without command line param

2015-03-26T16:25:27+00:00

Earlycon matching can only be triggered if 'earlycon=...' has been specified on the kernel command line. To workaround this limitation requires tight coupling between arches and specific serial drivers in order to start an earlycon. Devicetree avoids this limitation with a link table that contains the required data to match earlycons. Mirror this approach for earlycon match by name. Re-purpose EARLYCON_DECLARE to generate a table entry which associates name with setup() function. Re-purpose setup_earlycon() to scan this table for an earlycon match, which is registered if found. Declare one "earlycon" early_param, which calls setup_earlycon(). This design allows setup_earlycon() to be called directly with a param string (as if 'earlycon=...' had been set on the command line). Re-registration (either directly or by early_param) is prevented. Acked-by: Rob Herring Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

serial: earlycon: Refactor earlycon registration

2015-03-26T16:25:27+00:00

Separate earlycon matching from registration; add register_earlycon which initializes and registers the matched earlycon. Acked-by: Rob Herring Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

serial: earlycon: Skip parse_options() if empty string

2015-03-26T16:25:27+00:00

Earlycon param strings of the form earlycon= are rejected from parse_options() with an error (which, in turn, results in a NULL argument for the setup() method options parameter). Only pass non-empty string to parse_options(); this will enable handling actual parse errors differently than expected and allow formats. Acked-by: Rob Herring Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

serial: earlycon: Ignore parse_options() error code

2015-03-26T15:17:56+00:00

Because setup_earlycon() continues to attempt console registration if an error occurred parsing the option string, the actual value of the error code from parse_options() is ignored. Acked-by: Rob Herring Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

serial: earlycon: Move ->uartclk initialize

2015-03-26T15:17:55+00:00

Initializing the ->uartclk field is not related to option parsing; relocate from parse_options() to setup_earlycon() (which mirrors the behavior of of_setup_earlycon()). Acked-by: Rob Herring Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

serial: earlycon: Refactor parse_options into serial core

2015-03-07T02:55:07+00:00

Prepare to support console-defined matching; refactor the command line parameter string processing from parse_options() into a new core function, uart_parse_earlycon(), which decodes command line parameters of the form: earlycon=,io|mmio|mmio32,, console=,io|mmio|mmio32,, earlycon=,0x, console=,0x, Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty/serial: earlycon: Fix print for implied MMIO case

2014-11-06T03:45:52+00:00

For the case in which we just provide an address as an argument to the earlycon console type like: earlycon=msm_serial_dm,0xf991e000 We would report this as an IO port based mapping and not as MMIO. Simple fix to use the port->iotype to decide which message to print. Signed-off-by: Kumar Gala Acked-by: Mark RUtland Signed-off-by: Greg Kroah-Hartman