linux-kernel - Re: [PATCH 2/4] devicetree: serial: Document msm

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Message-Id: <CB6CE708-148D-4C36-AB4C-373DAB91B80E@codeaurora.org>
Date:	Tue, 20 Aug 2013 13:03:31 -0500
From:	Kumar Gala <galak@...eaurora.org>
To:	Stephen Boyd <sboyd@...eaurora.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-serial@...r.kernel.org,
	David Brown <davidb@...eaurora.org>, devicetree@...r.kernel.org
Subject: Re: [PATCH 2/4] devicetree: serial: Document msm_serial bindings


On Aug 20, 2013, at 12:00 PM, Stephen Boyd wrote:

> On 08/20/13 07:41, Kumar Gala wrote:
>> On Aug 19, 2013, at 4:39 PM, Stephen Boyd wrote:
>> 
>>> diff --git a/Documentation/devicetree/bindings/serial/msm_serial.txt b/Documentation/devicetree/bindings/serial/msm_serial.txt
>>> new file mode 100644
>>> index 0000000..a6efac3
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/serial/msm_serial.txt
>>> @@ -0,0 +1,82 @@
>>> +* MSM Serial UART and UARTDM
>>> +
>>> +There are two MSM serial hardware designs. UARTDM is designed for use with a
>>> +dma engine in high-speed use cases and the non-DM design is for lower speed use
>>> +cases. The two designs are mostly compatible from a software perspective except
>>> +the non-DM design can only read and write one character at a time and so the
>>> +register layout differs slightly.
>> I think you split this into two binding spec docs, one for each type of uart.
> 
> Should split into two files? I can do that.

yes.


>>> +UART
>>> +----
>>> +Required properties:
>>> +- compatible: Should contain "qcom,msm-uart"
>>> +- reg: Should contain UART register location and length. The first
>> first? is there more than one reg region?

?

>>> +       register shall specify the main control registers
>>> +- interrupts: Should contain UART interrupt.
>>> +- clocks: Should contain the core clock.
>>> +- clock-names: Should be "core_clk".
>>> +
>>> +Optional properties:
>>> +- dmas: Should contain dma specifiers for transmit and receive
>>> +- dma-names: Should contain "tx" for transmit and "rx" for receive
>> confused, above you say the non-DM doesn't support DMA so, why the optional props?
> 
> Ah sorry, copy pasta.
> 
>> 
>>> +
>>> +Example:
>>> +
>>> +A uart device with dma capabilities.
>>> +
>>> +serial@...00000 {
>>> +	compatible = "qcom,msm-uart";
>>> +	reg = <0xa9c00000 0x1000>;
>>> +	interrupts = <11>;
>>> +	clocks = <&uart_cxc>;
>>> +	clock-names = "core_clk";
>>> +	dmas = <&dma0 0>, <&dma0 1>;
>>> +	dma-names = "tx", "rx";
>>> +};
>>> +
>>> +UARTDM
>>> +------
>>> +Required properties:
>>> +- compatible: Should contain at least "qcom,msm-uartdm".
>>> +              A more specific property should be specified as follows depending
>>> +	      on the version:
>>> +		"qcom,msm-uartdm-v1.1"
>>> +		"qcom,msm-uartdm-v1.2"
>>> +		"qcom,msm-uartdm-v1.3"
>>> +		"qcom,msm-uartdm-v1.4"
>>> +- reg: Should contain UART register locations and lengths. The first
>>> +       register shall specify the main control registers. An optional second
>>> +       register location shall specify the GSBI control region.
>> Is GSBI region existing tied to particular versions (if so can we say that)
> 
> Not really. GSBI will always be related to v1.3 but not all v1.3
> hardware is part of a GSBI.

How about adding that into the binding.

>> reg-names?
> 
> Optional should be fine? The driver is already handling this without
> reg-names.
> 
>>> +- interrupts: Should contain UART interrupt.
>>> +- clocks: Should contain the core clock and the ahb clock.
>> nit, ahb in caps?
> 
> Done.

- k

-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

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