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    arm64: dts: marvell: de-duplicate CP110 description · 72a3713f
    Thomas Petazzoni 提交于
    One concept of Marvell Armada 7K/8K SoCs is that they are made of HW
    blocks composed of a variety of IPs (network, PCIe, SATA, XOR, SPI,
    I2C, etc.), and those HW blocks can be duplicated several times within
    a given SoC. The Armada 7K SoC has a single CP110 (so no duplication),
    while the Armada 8K SoC has two CP110. In the future, SoCs with more
    than 2 CP110s will be introduced.
    
    In current kernel versions, the master CP110 is described in
    armada-cp110-master.dtsi and the slave CP110 is described in
    armada-cp110-slave.dtsi. Those files are basically exactly the same,
    since they describe the same hardware. They only have a few
    differences:
    
     - Base address of the registers is different for the "config-space"
    
     - Base address of the PCIe registers, MEM, CONF and IO areas were
       different
    
     - Labels (and phandles pointing to them) of the nodes were different
       ("cpm" prefix in the master CP, "cps" prefix in the slave CP)
    
    This duplication issue has been discussed at the DT workshop [1] in
    Prague last October, and we presented on this topic [2]. The solution
    of using the C pre-processor to avoid this duplication has been
    validated by the people present in this DT workshop, and this patch
    simply implements what has been presented.
    
    We handle differences between the master CP and slave CP description
    using the C pre-processor, by defining a set of macros with different
    values armada-cp110.dtsi is included to instantiate one of the master
    or slave CP110.
    
    There are a few aspects that deserve additional explanations:
    
     - PCIe needs to be handled separately because it is not part of the
       config-space {...} node, since it has registers outside of the
       range covered by config-space {...}.
    
     - We need to defined CP110_BASE, CP110_PCIEx_BASE without 0x, because
       they are used for the unit address part of some DT nodes. But since
       they are also used for the "reg" property of the same nodes, we
       have an ADDRESSIFY() macro that prepends 0x to those values.
    
    We compared the resulting .dtb for armada-8040-db.dtb before and after
    this patch is applied, and the result is exactly the same, except for
    a few differences:
    
     - the SDHCI controller that was only described in the master CP110 is
       now also described in the slave CP110. Even though the SDHCI
       controller from the slave CP110 is indeed not usable (as it isn't
       wired to the outside world) it is technically part of the silicon,
       and therefore it is reasonable to also describe it to be part of
       the slave CP110. In addition, if we wanted to get this correct for
       the SDHCI controller, we should also do it for the NAND controller,
       for which the situation is even more complicated: in a single CP110
       configuration (Armada 7K), the usable NAND controller is in the
       master CP110, while in a dual CP110 configuration (Armada 8K), the
       usable NAND controller is in the slave CP110. Since that would add
       a lot of additional complexity for no good reason, and since the IP
       blocks are in fact really present in both CPs, we simply describe
       them in both CPs at the DT level.
    
     - the cp110-master and cp110-slave nodes are now named cpm and
       cps. We could have kept cp110-master and cp110-slave, but that
       would have required adding another CP110_xyz define, which didn't
       seem very useful.
    
    Note that this commit also gets rid of the armada-cp110-master.dtsi
    and armada-cp110-slave.dtsi files, as future SoCs will have more than
    2 CPs. Instead, we instantiate the CPs directly from the SoC-specific
    .dtsi files, i.e armada-70x0.dtsi and armada-80x0.dtsi.
    
    [1] https://elinux.org/Device_tree_kernel_summit_2017_etherpad
    [2] https://elinux.org/images/1/14/DTWorkshop2017-duplicate-data.pdf
    
    [gregory.clement@free-electrons.com: add back the "ARM64: dts: marvell:
    Fix clock resources for various node" commit]
    Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
    Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
    72a3713f
armada-cp110.dtsi 11.7 KB