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    SubjectRe: [PATCH v2 02/19] OpenRISC: Device tree
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    On Sun, 2011-07-03 at 14:51 -0600, Grant Likely wrote:
    > On Sat, Jul 2, 2011 at 3:15 PM, Jonas Bonn <jonas@southpole.se> wrote:
    > Does it really make sense to have an SoC node for this board? I
    > assume this is for a soft CPU system on a Diligent FPGA board. It is
    > best if the device tree structure matches the actual bus layout of the
    > chip and/or FPGA design. If the devices are directly on the CPU bus,
    > then it is better to do without an soc node entirely and just put
    > everything at the root.

    Not sure I quite understand the distinction here. Yes, it's a soft CPU,
    but conceptually it has an internal bus (Wishbone) comparable to the
    Avalon bus that the peripherals sit on. I'd say it's an SoC; but I need
    to ask: what constitutes a valid use of the "soc" node?

    > > diff --git a/arch/openrisc/kernel/setup.c b/arch/openrisc/kernel/setup.c
    > > index 49342e9..6ce6583 100644
    > > --- a/arch/openrisc/kernel/setup.c
    > > +++ b/arch/openrisc/kernel/setup.c
    > > @@ -173,8 +173,7 @@ void __init setup_cpuinfo(void)
    > > unsigned long iccfgr,dccfgr;
    > > unsigned long cache_set_size, cache_ways;;
    > >
    > > - cpu = (struct device_node *) of_find_compatible_node(NULL,
    > > - NULL, "opencores,openrisc-1200");
    > > + cpu = of_find_compatible_node(NULL, NULL, "opencores,openrisc-1200");
    >
    > This looks odd. Is it a stale hunk from a previous patch version?
    >

    Hmmm... no, it's a hunk that should have been in patch 01/19 of the
    series. That said, there's a bit of devicetree code in that patch too.
    Can I just say, "please have a look there, too", or do I need to pull
    those bits out into the devicetree patch?

    I've pasted in just the relevant parts from patch 01/19 below for ease
    of review.

    /Jonas

    From arch/openrisc/kernel/setup.c:

    +static inline unsigned int fcpu(struct device_node *cpu, char *n)
    +{
    + const int *val;
    + return (val = of_get_property(cpu, n, NULL)) ? *val : 0;
    +}
    +
    +void __init setup_cpuinfo(void)
    +{
    + struct device_node *cpu = NULL;
    + unsigned long iccfgr,dccfgr;
    + unsigned long cache_set_size, cache_ways;;
    +
    + cpu = (struct device_node *) of_find_compatible_node(NULL,
    + NULL,
    "opencores,openrisc-1200");
    + if (!cpu) {
    + panic("No compatible CPU found in device tree...\n");
    + }
    +
    + iccfgr = mfspr(SPR_ICCFGR);
    + cache_ways = 1 << (iccfgr & SPR_ICCFGR_NCW);
    + cache_set_size = 1 << ((iccfgr & SPR_ICCFGR_NCS) >> 3);
    + cpuinfo.icache_block_size = 16 << ((iccfgr & SPR_ICCFGR_CBS) >>
    7);
    + cpuinfo.icache_size = cache_set_size * cache_ways *
    cpuinfo.icache_block_size;
    +
    + dccfgr = mfspr(SPR_DCCFGR);
    + cache_ways = 1 << (dccfgr & SPR_DCCFGR_NCW);
    + cache_set_size = 1 << ((dccfgr & SPR_DCCFGR_NCS) >> 3);
    + cpuinfo.dcache_block_size = 16 << ((dccfgr & SPR_DCCFGR_CBS) >>
    7);
    + cpuinfo.dcache_size = cache_set_size * cache_ways *
    cpuinfo.dcache_block_size;
    +
    + cpuinfo.clock_frequency = fcpu(cpu, "clock-frequency");
    +
    + of_node_put(cpu);
    +
    + print_cpuinfo();
    +}
    +
    +/**
    + * or32_early_setup
    + *
    + * Handles the pointer to the device tree that this kernel is to use
    + * for establishing the available platform devices.
    + *
    + * For now, this is limited to using the built-in device tree. In the
    future,
    + * it is intended that this function will take a pointer to the device
    tree
    + * that is potentially built-in, but potentially also passed in by the
    + * bootloader, or discovered by some equally clever means...
    + */
    +
    +void __init or32_early_setup(void) {
    +
    + early_init_devtree((void *) __dtb_start);
    +
    + printk(KERN_INFO "Compiled-in FDT at 0x%08x\n",
    + (unsigned int) __dtb_start);
    +}
    +
    +const struct of_device_id openrisc_bus_ids[] = {
    + { .type = "soc", },
    + { .compatible = "soc", },
    + {},
    +};
    +
    +static int __init openrisc_device_probe(void)
    +{
    + of_platform_bus_probe(NULL, openrisc_bus_ids, NULL);
    + return 0;
    +}
    +device_initcall(openrisc_device_probe);





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