On Wed, Mar 18, 2015 at 6:29 PM, Maxime Ripard
<maxime.rip...@free-electrons.com> wrote:
> On Wed, Mar 18, 2015 at 11:24:01AM +0800, Chen-Yu Tsai wrote:
>> The A23 is a dual Cortex-A7. Add the logic to use the IPs used to
>> control the CPU configuration and the CPU power so that we can
>> bring up secondary CPUs at boot.
>>
>> Signed-off-by: Chen-Yu Tsai <w...@csie.org>
>> ---
>>
>> We can't use of_io_request_and_map() here, as it will conflict
>> with PRCM, and leave us without a serial console.
>>
>> I think a proper way to solve this would be a syscon device or
>> something like the mfd-simple device posted by Arnd.
>>
>> ---
>> Documentation/devicetree/bindings/arm/cpus.txt | 1 +
>> arch/arm/mach-sunxi/platsmp.c | 69
>> ++++++++++++++++++++++++++
>> 2 files changed, 70 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/arm/cpus.txt
>> b/Documentation/devicetree/bindings/arm/cpus.txt
>> index 8b9e0a95de31..40202d85b132 100644
>> --- a/Documentation/devicetree/bindings/arm/cpus.txt
>> +++ b/Documentation/devicetree/bindings/arm/cpus.txt
>> @@ -188,6 +188,7 @@ nodes to be present and contain the properties described
>> below.
>> # On ARM 32-bit systems this property is optional and
>> can be one of:
>> "allwinner,sun6i-a31"
>> + "allwinner,sun8i-a23"
>> "arm,psci"
>> "brcm,brahma-b15"
>> "marvell,armada-375-smp"
>> diff --git a/arch/arm/mach-sunxi/platsmp.c b/arch/arm/mach-sunxi/platsmp.c
>> index 587b0468efcc..e8483ec79d67 100644
>> --- a/arch/arm/mach-sunxi/platsmp.c
>> +++ b/arch/arm/mach-sunxi/platsmp.c
>> @@ -121,3 +121,72 @@ static struct smp_operations sun6i_smp_ops __initdata =
>> {
>> .smp_boot_secondary = sun6i_smp_boot_secondary,
>> };
>> CPU_METHOD_OF_DECLARE(sun6i_a31_smp, "allwinner,sun6i-a31", &sun6i_smp_ops);
>> +
>> +static void __init sun8i_smp_prepare_cpus(unsigned int max_cpus)
>> +{
>> + struct device_node *node;
>> +
>> + node = of_find_compatible_node(NULL, NULL, "allwinner,sun8i-a23-prcm");
>> + if (!node) {
>> + pr_err("Missing A23 PRCM node in the device tree\n");
>> + return;
>> + }
>> +
>> + prcm_membase = of_iomap(node, 0);
>> + if (!prcm_membase) {
>> + pr_err("Couldn't map A23 PRCM registers\n");
>> + return;
>> + }
>> +
>> + node = of_find_compatible_node(NULL, NULL,
>> + "allwinner,sun8i-a23-cpuconfig");
>> + if (!node) {
>> + pr_err("Missing A23 CPU config node in the device tree\n");
>> + return;
>> + }
>> +
>> + cpucfg_membase = of_iomap(node, 0);
>> + if (!cpucfg_membase)
>> + pr_err("Couldn't map A23 CPU config registers\n");
>> +
>> +}
>> +
>> +static int sun8i_smp_boot_secondary(unsigned int cpu,
>> + struct task_struct *idle)
>> +{
>> + u32 reg;
>> +
>> + if (!(prcm_membase && cpucfg_membase))
>> + return -EFAULT;
>> +
>> + spin_lock(&cpu_lock);
>> +
>> + /* Set CPU boot address */
>> + writel(virt_to_phys(secondary_startup),
>> + cpucfg_membase + CPUCFG_PRIVATE0_REG);
>
> One question I couldn't find any answer to is that does the SMP bit is
> set in secondary_startup?
>
> I couldn't find where it was set, but it still looks like the right
> thing to do, so I would expect the code to do that.
I don't see it either. The sun8i code is just the sun6i code with the
power clamps removed. And sun6i secondary_startup was removed some time
ago in commit 1146b600044d ("ARM: sunxi: fix build for THUMB2_KERNEL").
ChenYu
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