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Commit 8d0d56ba authored Feb 02, 2015 by Vineet Gupta

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>

parent 556cc1c5

Documentation/devicetree/bindings/arc/axs101.txt

+1 −1

Original line number	Diff line number	Diff line
		@@ -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

		Required root node properties:
		- compatible = "snps,axs101";
		- compatible = "snps,axs101", "snps,arc-sdp";

arch/arc/boot/dts/axs101.dts

+2 −2

Original line number	Diff line number	Diff line
		@@ -13,9 +13,9 @@
		/include/ "axs10x_mb.dtsi"

		/ {
		compatible = "snps,axs101";
		compatible = "snps,axs101", "snps,arc-sdp";

		chosen {
		bootargs = "console=tty0 console=ttyS3,115200n8 consoleblank=0";
		bootargs = "earlycon=uart8250,mmio32,0xe0022000,115200n8 console=tty0 console=ttyS3,115200n8 consoleblank=0";
		};
		};

arch/arc/kernel/devtree.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -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"))
		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
		arc_base_baud = core_clk;
		}