On i.MX53 it is necessary to set the DBG_EN bit in the platform GPC register to enable access to PMU counters other than the cycle counter.
Signed-off-by: Sebastian Reichel <[email protected]> --- arch/arm/mach-imx/mach-imx53.c | 39 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 38 insertions(+), 1 deletion(-) diff --git a/arch/arm/mach-imx/mach-imx53.c b/arch/arm/mach-imx/mach-imx53.c index 07c2e8dca494..658e28604dca 100644 --- a/arch/arm/mach-imx/mach-imx53.c +++ b/arch/arm/mach-imx/mach-imx53.c @@ -28,10 +28,47 @@ static void __init imx53_init_early(void) mxc_set_cpu_type(MXC_CPU_MX53); } +#define MXC_CORTEXA8_PLAT_GPC 0x63fa0004 +#define GPC_DBG_EN BIT(16) + +/* + * This enables the DBGEN bit in ARM_GPC register, which is + * required for accessing some performance counter features. + * Technically it is only required while perf is used, but to + * keep the source code simple we just enable it all the time + * when the kernel configuration allows using the feature. + */ +static void imx53_pmu_init(void) +{ + void __iomem *gpc_reg; + struct device_node *node; + u32 gpc; + + if (!IS_ENABLED(CONFIG_ARM_PMU)) + return; + + node = of_find_compatible_node(NULL, NULL, "arm,cortex-a8-pmu"); + if (!node) + return; + + if (!of_property_read_bool(node, "secure-reg-access")) + return; + + gpc_reg = ioremap(MXC_CORTEXA8_PLAT_GPC, 4); + if (!gpc_reg) { + pr_warning("unable to map GPC to enable perf\n"); + return; + } + + gpc = readl_relaxed(gpc_reg); + gpc |= GPC_DBG_EN; + writel_relaxed(gpc, gpc_reg); +} + static void __init imx53_dt_init(void) { imx_src_init(); - + imx53_pmu_init(); imx_aips_allow_unprivileged_access("fsl,imx53-aipstz"); } -- 2.15.1
