Hi,
On Thu, Dec 20, 2012 at 11:44:01AM +0200, Hiroshi Doyu wrote:
> The method to detect the number of CPU cores on Cortex-A9 MPCore and
> Cortex-A15 MPCore is different. On Cortex-A9 MPCore we can get this
> information from the Snoop Control Unit(SCU). On Cortex-A15 MPCore we
> have to read it from the system coprocessor(CP15), because the SCU on
> Cortex-A15 MPCore does not have software readable registers. This
> patch selects the correct method at runtime based on the CPU ID.
>
> Signed-off-by: Hiroshi Doyu <hdoyu@xxxxxxxxxx>
> ---
> arch/arm/mach-tegra/platsmp.c | 31 ++++++++++++++++++++++++++++---
> 1 file changed, 28 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm/mach-tegra/platsmp.c b/arch/arm/mach-tegra/platsmp.c
> index 1b926df..68e76ef 100644
> --- a/arch/arm/mach-tegra/platsmp.c
> +++ b/arch/arm/mach-tegra/platsmp.c
> @@ -23,6 +23,7 @@
> #include <asm/hardware/gic.h>
> #include <asm/mach-types.h>
> #include <asm/smp_scu.h>
> +#include <asm/cputype.h>
>
> #include <mach/powergate.h>
>
> @@ -34,9 +35,13 @@
> #include "common.h"
> #include "iomap.h"
>
> +#define CPU_MASK 0xff0ffff0
> +#define CPU_CORTEX_A9 0x410fc090
> +#define CPU_CORTEX_A15 0x410fc0f0
> +
> extern void tegra_secondary_startup(void);
>
> -static void __iomem *scu_base = IO_ADDRESS(TEGRA_ARM_PERIF_BASE);
> +static void __iomem *scu_base;
>
> #define EVP_CPU_RESET_VECTOR \
> (IO_ADDRESS(TEGRA_EXCEPTION_VECTORS_BASE) + 0x100)
> @@ -149,7 +154,26 @@ done:
> */
> static void __init tegra_smp_init_cpus(void)
> {
> - unsigned int i, ncores = scu_get_core_count(scu_base);
> + unsigned int i, cpu_id, ncores;
> + u32 l2ctlr;
> + phys_addr_t pa;
> +
> + cpu_id = read_cpuid(CPUID_ID) & CPU_MASK;
> + switch (cpu_id) {
> + case CPU_CORTEX_A15:
> + asm("mrc p15, 1, %0, c9, c0, 2\n" : "=r" (l2ctlr));
> + ncores = ((l2ctlr >> 24) & 3) + 1;
> + break;
> + case CPU_CORTEX_A9:
> + /* Get SCU physical base */
> + asm("mrc p15, 4, %0, c15, c0, 0" : "=r" (pa));
> + scu_base = IO_ADDRESS(pa);
> + ncores = scu_get_core_count(scu_base);
> + break;
> + default:
> + BUG();
instead of bugging out, how about setting ncores to 1 instead ?
--
balbi
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