serial_core: add pci uart early console support
Subsystems (3)
PATCH v4 1/2 serial_core: add pci uart early console support
On some Intel Atom SoCs, the legacy IO port UART(0x3F8) is not available. Instead, a 8250 compatible PCI uart can be used as early console. This patch adds pci support to the 8250 early console driver uart8250. For example, to enable pci uart(00:21.3) as early console on these platforms, append the following line to the kernel command line (assume baud rate is 115200):
earlyprintk=uart8250,pci32,0:24.2,115200n8
--- arch/x86/Kconfig | 1 + drivers/pci/Kconfig | 11 +++ drivers/tty/serial/earlycon.c | 9 +++ drivers/tty/serial/serial_core.c | 145 ++++++++++++++++++++++++++++++++++++++- 4 files changed, 164 insertions(+), 2 deletions(-)
arch/x86/Kconfig +1 -0
@@ -143,6 +143,7 @@ config X86 select ACPI_LEGACY_TABLES_LOOKUP if ACPI select X86_FEATURE_NAMES if PROC_FS select SRCU + select PCI_EARLY if PCI config INSTRUCTION_DECODER def_bool y
drivers/pci/Kconfig +11 -0
@@ -114,4 +114,15 @@ config PCI_LABEL def_bool y if (DMI || ACPI) select NLS +config PCI_EARLY + bool "Early PCI access" + depends on PCI + default n + help + This option indicates that a group of APIs are available (in + asm/pci-direct.h) so the kernel can access pci config registers + before the PCI subsystem is initialized. Any arch that supports + early pci APIs should enable this option which is required by + arch independent codes, e.g. uart8250 pci early console driver. + source "drivers/pci/host/Kconfig"
drivers/tty/serial/earlycon.c +9 -0
@@ -193,6 +193,15 @@ static int __init param_setup_earlycon(char *buf) }early_param ("earlycon" , param_setup_earlycon); +/* x86 uses "earlyprintk=xxx", so we keep the compatibility here */ +#ifdef CONFIG_X86 +static int __init param_setup_earlycon_x86 (char *buf) +{ +return param_setup_earlycon (buf); +} +early_param ("earlyprintk" , param_setup_earlycon_x86); +#endif +int __init of_setup_earlycon (unsigned long addr,int (*setup)(struct earlycon_device *,const char *)) {
drivers/tty/serial/serial_core.c +143 -2
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Signature · 1 line
1.9.1
Greg Kroah-Hartman
maintainerQuoted 8 lines · Bin Gao
On some Intel Atom SoCs, the legacy IO port UART(0x3F8) is not available. Instead, a 8250 compatible PCI uart can be used as early console. This patch adds pci support to the 8250 early console driver uart8250. For example, to enable pci uart(00:21.3) as early console on these platforms, append the following line to the kernel command line (assume baud rate is 115200):
earlyprintk=uart8250,pci32,0:24.2,115200n8
Quoted 7 lines
Signed-off-by Bin Gao <[email protected]>--- arch/x86/Kconfig | 1 + drivers/pci/Kconfig | 11 +++ drivers/tty/serial/earlycon.c | 9 +++ drivers/tty/serial/serial_core.c | 145 ++++++++++++++++++++++++++++++++++++++- 4 files changed, 164 insertions(+), 2 deletions(-)
What changed in this version?
You can't just put "v4" without giving us some hint as to the differences here, sorry.
Quoted 4 lines · Greg Kroah-Hartman
What changed in this version?
You can't just put "v4" without giving us some hint as to the differences here, sorry.
I just resent [PATCH v4 1/2] with "Changes in v4" added. There is no change for patch 2/2 since the first version, so I didn't resend [PATCH v4 2/2].
Thanks,
Bin
Greg Kroah-Hartman
maintainerQuoted 9 lines · Bin Gao
Quoted 4 lines · Greg Kroah-Hartman
What changed in this version?
You can't just put "v4" without giving us some hint as to the differences here, sorry.
I just resent [PATCH v4 1/2] with "Changes in v4" added. There is no change for patch 2/2 since the first version, so I didn't resend [PATCH v4 2/2].
Please do otherwise I'm apt to get very confused and just not want to apply any of these...