From fb11ffe74c794a510a29ad8cd81d4e9e3b1c9158 Mon Sep 17 00:00:00 2001 From: Rob Herring Date: Thu, 27 Mar 2014 08:07:01 -0500 Subject: of/fdt: add FDT serial scanning for earlycon This adds FDT parsing of {linux,}stdout-path to setup an early serial console. Enabling of the early console is triggered with "earlycon" (with no options) on the kernel command line. Platforms must either have fixmap permanent mapping support, have a functioning ioremap when early params are parsed, or explicitly call early_init_dt_scan_chosen_serial from architecture code. Signed-off-by: Rob Herring Acked-by: Grant Likely --- drivers/of/fdt.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) (limited to 'drivers') diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index a6f83ea107ae..1fbeab27075f 100644 --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -21,6 +21,7 @@ #include #include #include +#include #include /* for COMMAND_LINE_SIZE */ #include @@ -696,6 +697,61 @@ static inline void early_init_dt_check_for_initrd(unsigned long node) } #endif /* CONFIG_BLK_DEV_INITRD */ +#ifdef CONFIG_SERIAL_EARLYCON +extern struct of_device_id __earlycon_of_table[]; + +int __init early_init_dt_scan_chosen_serial(void) +{ + int offset; + const char *p; + int l; + const struct of_device_id *match = __earlycon_of_table; + const void *fdt = initial_boot_params; + + offset = fdt_path_offset(fdt, "/chosen"); + if (offset < 0) + offset = fdt_path_offset(fdt, "/chosen@0"); + if (offset < 0) + return -ENOENT; + + p = fdt_getprop(fdt, offset, "stdout-path", &l); + if (!p) + p = fdt_getprop(fdt, offset, "linux,stdout-path", &l); + if (!p || !l) + return -ENOENT; + + /* Get the node specified by stdout-path */ + offset = fdt_path_offset(fdt, p); + if (offset < 0) + return -ENODEV; + + while (match->compatible) { + unsigned long addr; + if (fdt_node_check_compatible(fdt, offset, match->compatible)) { + match++; + continue; + } + + addr = fdt_translate_address(fdt, offset); + if (!addr) + return -ENXIO; + + of_setup_earlycon(addr, match->data); + return 0; + } + return -ENODEV; +} + +static int __init setup_of_earlycon(char *buf) +{ + if (buf) + return 0; + + return early_init_dt_scan_chosen_serial(); +} +early_param("earlycon", setup_of_earlycon); +#endif + /** * early_init_dt_scan_root - fetch the top level address and size cells */ -- cgit v1.2.3-55-g7522