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ARC: [axs101] support early 8250 uart 

Earlycon calculates UART clock as "BASE_BAUD * 16". In case of ARC
"BASE_BAUD" is calculated dynamically in runtime, basically it is an
alias to arc_early_base_baud(), which in turn just does
"arc_base_baud/16".

8250 UART on AXS/SDP board uses 33.3MHz clock source which is set in
"arc_base_baud" with this change.

Additional compatibility string "snps,arc-sdp" is introduced as well
because there're different flavours of AXS boards but they all share the
same motherboard and so it's possible to re-use the same code for
motherbord even if CPU daughterboard changes.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2015-02-02 19:23:21 +05:30
parent 556cc1c5f5
commit 8d0d56ba24
3 changed files with 5 additions and 3 deletions
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2
Documentation/devicetree/bindings/arc/axs101.txt
View File

@ -4,4 +4,4 @@ Synopsys DesignWare ARC Software Development Platforms Device Tree Bindings
SDP Main Board with an AXC001 CPU Card hoisting ARC700 core in silicon SDP Main Board with an AXC001 CPU Card hoisting ARC700 core in silicon
Required root node properties: Required root node properties:
- compatible = "snps,axs101"; - compatible = "snps,axs101", "snps,arc-sdp";

4
arch/arc/boot/dts/axs101.dts
View File

@ -13,9 +13,9 @@
/include/ "axs10x_mb.dtsi" /include/ "axs10x_mb.dtsi"
/ { / {
compatible = "snps,axs101"; compatible = "snps,axs101", "snps,arc-sdp";
chosen { chosen {
bootargs = "console=tty0 console=ttyS3,115200n8 consoleblank=0"; bootargs = "earlycon=uart8250,mmio32,0xe0022000,115200n8 console=tty0 console=ttyS3,115200n8 consoleblank=0";
}; };
}; };

2
arch/arc/kernel/devtree.c
View File

@ -32,6 +32,8 @@ static void __init arc_set_early_base_baud(unsigned long dt_root)
if (of_flat_dt_is_compatible(dt_root, "abilis,arc-tb10x")) if (of_flat_dt_is_compatible(dt_root, "abilis,arc-tb10x"))
arc_base_baud = core_clk/3; arc_base_baud = core_clk/3;
else if (of_flat_dt_is_compatible(dt_root, "snps,arc-sdp"))
arc_base_baud = 33333333; /* Fixed 33MHz clk */
else else
arc_base_baud = core_clk; arc_base_baud = core_clk;
} }