linux-kernel - Re: [PATCH v3 3/9] clk: qoriq: provide constants for the type

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Date:   Mon, 09 Nov 2020 23:39:25 +0100
From:   Michael Walle <michael@...le.cc>
To:     Rob Herring <robh@...nel.org>
Cc:     linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>, Li Yang <leoyang.li@....com>,
        "Y . b . Lu" <yangbo.lu@....com>,
        Xiaowei Bao <xiaowei.bao@....com>,
        Ashish Kumar <Ashish.Kumar@....com>,
        Vladimir Oltean <vladimir.oltean@....com>
Subject: Re: [PATCH v3 3/9] clk: qoriq: provide constants for the type

Am 2020-11-09 23:05, schrieb Rob Herring:
> On Sun, Nov 08, 2020 at 07:51:07PM +0100, Michael Walle wrote:
>> To avoid future mistakes in the device tree for the clockgen module, 
>> add
>> constants for the clockgen subtype as well as a macro for the PLL
>> divider.
>> 
>> Signed-off-by: Michael Walle <michael@...le.cc>
>> ---
>> Changes since v2:
>>  - new patch
>> 
>>  drivers/clk/clk-qoriq.c                        | 13 +++++++------
>>  include/dt-bindings/clock/fsl,qoriq-clockgen.h | 15 +++++++++++++++
>>  2 files changed, 22 insertions(+), 6 deletions(-)
>>  create mode 100644 include/dt-bindings/clock/fsl,qoriq-clockgen.h
>> 
>> diff --git a/drivers/clk/clk-qoriq.c b/drivers/clk/clk-qoriq.c
>> index 46101c6a20f2..70aa521e7e7f 100644
>> --- a/drivers/clk/clk-qoriq.c
>> +++ b/drivers/clk/clk-qoriq.c
>> @@ -7,6 +7,7 @@
>> 
>>  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>> 
>> +#include <dt-bindings/clock/fsl,qoriq-clockgen.h>
>>  #include <linux/clk.h>
>>  #include <linux/clk-provider.h>
>>  #include <linux/clkdev.h>
>> @@ -1368,33 +1369,33 @@ static struct clk *clockgen_clk_get(struct 
>> of_phandle_args *clkspec, void *data)
>>  	idx = clkspec->args[1];
>> 
>>  	switch (type) {
>> -	case 0:
>> +	case QORIQ_CLK_SYSCLK:
>>  		if (idx != 0)
>>  			goto bad_args;
>>  		clk = cg->sysclk;
>>  		break;
>> -	case 1:
>> +	case QORIQ_CLK_CMUX:
>>  		if (idx >= ARRAY_SIZE(cg->cmux))
>>  			goto bad_args;
>>  		clk = cg->cmux[idx];
>>  		break;
>> -	case 2:
>> +	case QORIQ_CLK_HWACCEL:
>>  		if (idx >= ARRAY_SIZE(cg->hwaccel))
>>  			goto bad_args;
>>  		clk = cg->hwaccel[idx];
>>  		break;
>> -	case 3:
>> +	case QORIQ_CLK_FMAN:
>>  		if (idx >= ARRAY_SIZE(cg->fman))
>>  			goto bad_args;
>>  		clk = cg->fman[idx];
>>  		break;
>> -	case 4:
>> +	case QORIQ_CLK_PLATFORM_PLL:
>>  		pll = &cg->pll[PLATFORM_PLL];
>>  		if (idx >= ARRAY_SIZE(pll->div))
>>  			goto bad_args;
>>  		clk = pll->div[idx].clk;
>>  		break;
>> -	case 5:
>> +	case QORIQ_CLK_CORECLK:
>>  		if (idx != 0)
>>  			goto bad_args;
>>  		clk = cg->coreclk;
>> diff --git a/include/dt-bindings/clock/fsl,qoriq-clockgen.h 
>> b/include/dt-bindings/clock/fsl,qoriq-clockgen.h
>> new file mode 100644
>> index 000000000000..ddec7d0bdc7f
>> --- /dev/null
>> +++ b/include/dt-bindings/clock/fsl,qoriq-clockgen.h
>> @@ -0,0 +1,15 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +
>> +#ifndef DT_CLOCK_FSL_QORIQ_CLOCKGEN_H
>> +#define DT_CLOCK_FSL_QORIQ_CLOCKGEN_H
>> +
>> +#define QORIQ_CLK_SYSCLK	0
>> +#define QORIQ_CLK_CMUX		1
>> +#define QORIQ_CLK_HWACCEL	2
>> +#define QORIQ_CLK_FMAN		3
>> +#define QORIQ_CLK_PLATFORM_PLL	4
>> +#define QORIQ_CLK_CORECLK	5
>> +
>> +#define QORIQ_CLK_PLL_DIV(x)	((x) - 1)
> 
> This is not used and doesn't seem like part of the ABI (shared with dts
> files).

TBH I haven't found a nice way to integrate this macro into the clock 
driver. It is used in the device tree for the type PLATFORM_PLL.
Previously, you had "<&clockgen 4 1>", where 4 is the PLATFORM_PLL and 1 
is actually "div-by-2". Thus I replaced it by <&clockgen 
QORIQ_CLK_PLATFORM_PLL QORIQ_CLK_PLL_DIV(2)>. (I just realized that 
QORIQ_CLK_PLL_DIV_BY(2) might be a better name.)

I already figured, that this might be a problem, if that macro isn't 
used in the driver.

-michael