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List:       linux-arm-kernel
Subject:    Re: [PATCH 6/6] at91: dt: sam9261: Added DM9000 in the device tree
From:       Arnd Bergmann <arnd () arndb ! de>
Date:       2013-12-31 19:19:51
Message-ID: 4526077.qASk8HSHKP () wuerfel
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On Tuesday 31 December 2013 17:32:14 jjhiblot@traphandler.com wrote:
> 
> +                       ethernet@30000000 {
> +                               compatible = "davicom,dm9000";
> +                               reg = <0x30000000 0x2 0x30000004 0x2>;
> +                               interrupt-parent = <&pioC>;
> +                               interrupts = <11 IRQ_TYPE_EDGE_BOTH>;
> +                               local-mac-address = [00 00 de ad be ef];
> +                               davicom,no-eeprom;
> +
> +                               smc,cs = <2>;
> +                               smc,ncs_read_setup = <0>;
> +                               smc,nrd_setup = <2>;
> +                               smc,ncs_write_setup = <0>;
> +                               smc,nwe_setup = <2>;
> +                               smc,ncs_read_pulse = <8>;
> +                               smc,nrd_pulse = <4>;
> +                               smc,ncs_write_pulse = <8>;
> +                               smc,nwe_pulse = <4>;
> +                               smc,read_cycle = <16>;
> +                               smc,write_cycle = <16>;
> +                               smc,tdf_cycles = <1>;
> +                               smc,tdf_optimized = <0>;
> +                               smc,page_size = <0>;
> +                               smc,byte_access_type = <1>;
> +                               smc,bus_width = <1>;
> +                               smc,nwait_mode = <0>;
> +                               smc,read_mode = <1>;
> +                               smc,write_mode = <1>;
> +                       };

I don't like how this forces you to mix the properties
of the ethernet device with the properties of the smc
port. I would also like to see the address translation
reflected in the DT nodes. This should probably just work
out if you restructure the DT representation, and won't need
changes in the driver.

How about this:

	smc: smc@ffffec00 {
		#address-cells = <2>; /* cs, address */
		#size-cells = <1>;
		ranges = <2 0 0x30000000 0x10000000>
			 <3 0 0x40000000 0x10000000>;

		extbus@2.0 {
			compatible = "simple-bus";
			#address-cells = <1>;
			#size-cells = <1>;
			ranges = <0 2 0 0x10000000>;
			smc,ncs_read_setup = <0>;
			smc,nrd_setup = <2>;
			smc,...

			ethernet@0 {
				compatible = "davicom,dm9000";
				reg = <0x0 0x2> <0x4 0x2>;
			};
		};
	};

If each bus interface has a fixed range of registers, you can actually
collapse the upper two nodes again and just have one device per
chipselect.

	Arnd

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