On Mon, Feb 26, 2018 at 02:47:41PM +0100, Sebastian Reichel wrote: > Hi Shawn, > > On Sat, Feb 24, 2018 at 03:45:44PM +0800, Shawn Guo wrote: > > On Mon, Feb 12, 2018 at 01:39:44PM +0100, Sebastian Reichel wrote: > > > 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 <sebastian.reic...@collabora.co.uk> > > > --- > > > 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 > > > > The base address should be retrieved from device tree. > > DT has no entry for 0x63fa0000-0x63fa3fff. iMX53 TRM lists it as "ARM > Platform" > with 8 platform specific 32 bit registers. Do you think it's worth the trouble > adding a new binding? Do you have a suggestion for a compatible value?
Looking at it more closely, I feel that patching every single platform which needs to set up additional register for secure-reg-access support doesn't really scale. Can we have pmu driver do it with a phandle in DT pointing to the register and bit that need to be configured? Shawn > > > +#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 > > >