Samsung SoCs: preparation for single kernel

[Kyungmin Park]

On Wed, Jun 23, 2010 at 10:54 AM, Eric Miao <eric.y.miao at gmail.com> wrote:
> On Wed, Jun 23, 2010 at 9:47 AM, Kyungmin Park <kmpark at infradead.org> wrote:
>> On Wed, Jun 23, 2010 at 9:50 AM, Eric Miao <eric.y.miao at gmail.com> wrote:
>>> On Wed, Jun 23, 2010 at 7:27 AM, Kyungmin Park <kmpark at infradead.org> wrote:
>>>> To Ben,
>>>>
>>>> I really need single kernel for s5pc110 (cortex A8) and s5pc210
>>>> (cortex A9) at least.
>>>> Fortunately arm move to these approaches recently. but current Samsung
>>>> SoCs not prepare these one.
>>>>
>>>> So I wonder do you have a plan or how to address these issues?
>>>> How to assign the address at resources and use it at runtime?
>>>>
>>>> Personally I want to use cpu_is_*. but you reject it to use.
>>>> Other way is that we can create the base address variables and assign
>>>> it at init time.
>>>>
>>>> Please give your opinions.
>>>>
>>>> Thank you,
>>>> Kyungmin Park
>>>>
>>>> e.g., cpu_is_* usage at OMAP tree
>>>>
>>>> static void omap_init_mcspi(void)
>>>> {
>>>>        if (cpu_is_omap44xx())
>>>>                omap4_mcspi_fixup();
>>>>
>>>>        platform_device_register(&omap2_mcspi1);
>>>>        platform_device_register(&omap2_mcspi2);
>>>>
>>>>        if (cpu_is_omap2430() || cpu_is_omap343x() || cpu_is_omap44xx())
>>>>                omap2_mcspi3_init();
>>>>
>>>>        if (cpu_is_omap343x() || cpu_is_omap44xx())
>>>>                omap2_mcspi4_init();
>>>> }
>>>
>>> Just my two cents: cpu_is_*() can be used, but only when absolutely necessary.
>>> The s3c does a CPU detection at startup, so I guess the usage of cpu_is_*()
>>> can be even reduced.
>>
>> My concern is that most device resources use the S3C_* or S5P_* prefix
>> and defined at each arch differently.
>>
>> E.G., mmc resource drivers use the S3C_PA_HSMMC0. but each mach has
>> different base address.
>> then how to handle this or make it possible?
>>
>
> Now you have
>
> s5pv210_device_hsmmc0
> s5pc100_device_hsmmc0
> s3c64xx_device_hsmmc0
> ....
>
> each with a different base.

Good, then wait Ben's opinions.

>
>> #define S5PV210_PA_HSMMC(x)     (0xEB000000 + ((x) * 0x100000))
>> #define S3C_PA_HSMMC0           S5PV210_PA_HSMMC(0)
>> #define S3C_PA_HSMMC1           S5PV210_PA_HSMMC(1)
>> #define S3C_PA_HSMMC2           S5PV210_PA_HSMMC(2)
>>
>> #define S5PC100_PA_HSMMC(x)     (0xED800000 + ((x) * 0x100000))
>> #define S3C_PA_HSMMC0           S5PC100_PA_HSMMC(0)
>> #define S3C_PA_HSMMC1           S5PC100_PA_HSMMC(1)
>> #define S3C_PA_HSMMC2           S5PC100_PA_HSMMC(2)
>>
>> #define S3C64XX_PA_HSMMC(x)     (0x7C200000 + ((x) * 0x100000))
>> #define S3C64XX_PA_HSMMC0       S3C64XX_PA_HSMMC(0)
>> #define S3C64XX_PA_HSMMC1       S3C64XX_PA_HSMMC(1)
>> #define S3C64XX_PA_HSMMC2       S3C64XX_PA_HSMMC(2)
>> #define S3C_PA_HSMMC0           S3C64XX_PA_HSMMC0
>> #define S3C_PA_HSMMC1           S3C64XX_PA_HSMMC1
>> #define S3C_PA_HSMMC2           S3C64XX_PA_HSMMC2
>>
>>>
>>> I'm not sure if the above case is a good reference or not. The omap_init_mcspi
>>> is called from omap2_init_devices(), while the registration can actually be
>>> made into the board init code when that device is used (some of the McSPIs are
>>> not used, and it's not necessary to register them), and the differences be
>>> handled in the driver.
>>
>> that's just example how to use cpu_is_* in others. the current schme
>> in samsung SoCs. we passed the different platform name for each arch.
>> e.g., s3c2410_i2c or s3c2440_i2c then i2c driver detect it and handle
>> properly. of course it assume base address is set correctly as above.
>
> For the device driver, when you register two different i2c devices:
>
> struct platform_device s3c2410_device_i2c {
>        .name   = "s3c2410-i2c",
>        ...
> };
>
> struct platform_device s3c2440_device_i2c {
>        .name   = "s3c2440-i2c",
>        ...
> };
>
> And register the corresponding one in your board code (your board code
> knows exactly which one to register, no? )
>
> And then in your i2c driver, you declare:
>
> const static struct platform_device_id s3c_i2c_ids[] = {
>        { "s3c2410-i2c", S3C2410_SPECIFIC_FLAGS },
>        { "s3c2440-i2c", S3C2440_SPECIFIC_FLAGS },
>        .....
> };
>
> Now you have S3C2410_SPECIFIC_FLAGS and S3C2440_SPECIFIC_FLAGS for your
> device driver to distinguish between the differences. Normally, the
> differences won't be much, and make sure you have good abstraction of
> those _SPECIFIC_FLAGS.

It's already done.
>>
>> Thank you,
>> Kyungmin Park
>>>
>>>>
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>>>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>>>
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>>
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