On Fri, Jul 06, 2018 at 12:43:52PM +0100, Mark Rutland wrote: > Please see the devicetree spec [1], section 2.3.4. Valid values are: > > * "okay" // equivalent to no status property present > * "disabled" > * "fail" > * "fail-sss" Nice tip, thx.
> I'm a bit confused. You write (1 << cpu) into cv<29, 0>, to enable a > particular CPU, so I assume that bit uniquely identifies a CPU, Yes, you're right and cr<29, 0>'s bit uniquely identifies a cpu. > and > therefore the reg is some unique ID for the CPU. static int csky_of_cpu(struct device_node *node) { const char *status; if (of_property_read_string(node, "status", &status)) status = "okay"; if (strcmp(status, "disabled") == 0) goto error; return 1; error: return 0; } void __init setup_smp(void) { struct device_node *node = NULL; int i = 0; while ((node = of_find_node_by_type(node, "cpu"))) { if (!csky_of_cpu(node)) continue; set_cpu_possible(i, true); set_cpu_present(i, true); i++; } } Hmm? No <reg> in next version patch, it's no use. > I see. > > Is this SMP bringup mechanism architectual, or are you likely to need > another mechanism to turn on CPUs on future chips? It's the only SMP bringup mechanism architectual for C-SKY SMP. There is no another way in future and SOC vendor couldn't change it. > You probably want to use an enable-method property to describe this. No, thx. Guo Ren