Re: [PATCH v3 19/26] coresight: etm4x: Detect access early on the target CPU

Mathieu Poirier
2020-11-06T20:34:44Z

On Wed, Oct 28, 2020 at 10:09:38PM +0000, Suzuki K Poulose wrote:
> In preparation to detect the support for system instruction
> support, move the detection of the device access to the target
> CPU.
>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
> .../coresight/coresight-etm4x-core.c | 45 ++++++++++++++++---
> 1 file changed, 40 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index f038bb10bc78..308674ab746c 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -56,6 +56,11 @@ static u64 etm4_get_access_type(struct etmv4_config *config);
>
> static enum cpuhp_state hp_online;
>
> +struct etm_init_arg {

s/etm_init_arg/etm4_init_arg

> + struct etmv4_drvdata *drvdata;
> + struct csdev_access *csa;
> +};
> +
> u64 etm4x_sysreg_read(struct csdev_access *csa,
> u32 offset,
> bool _relaxed,
> @@ -669,6 +674,22 @@ static const struct coresight_ops etm4_cs_ops = {
> .source_ops = &etm4_source_ops,
> };
>
> +static bool etm_init_iomem_access(struct etmv4_drvdata *drvdata,
> + struct csdev_access *csa)
> +{
> + *csa = CSDEV_ACCESS_IOMEM(drvdata->base);
> + return true;
> +}
> +
> +static bool etm_init_csdev_access(struct etmv4_drvdata *drvdata,
> + struct csdev_access *csa)
> +{
> + if (drvdata->base)
> + return etm_init_iomem_access(drvdata, csa);
> +
> + return false;
> +}

Returning a boolean rather than an int for the above two functions seems odd to
me.

> +
> static void etm4_init_arch_data(void *info)
> {
> u32 etmidr0;
> @@ -677,11 +698,22 @@ static void etm4_init_arch_data(void *info)
> u32 etmidr3;
> u32 etmidr4;
> u32 etmidr5;
> - struct etmv4_drvdata *drvdata = info;
> - struct csdev_access tmp_csa = CSDEV_ACCESS_IOMEM(drvdata->base);
> - struct csdev_access *csa = &tmp_csa;
> + struct etm_init_arg *init_arg = info;
> + struct etmv4_drvdata *drvdata;
> + struct csdev_access *csa;
> int i;
>
> + drvdata = init_arg->drvdata;
> + csa = init_arg->csa;
> +
> + /*
> + * If we are unable to detect the access mechanism,
> + * or unable to detect the trace unit type, fail
> + * early.
> + */
> + if (!etm_init_csdev_access(drvdata, csa))
> + return;
> +
> /* Make sure all registers are accessible */
> etm4_os_unlock_csa(drvdata, csa);
> etm4_cs_unlock(drvdata, csa);
> @@ -1524,6 +1556,7 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
> struct etmv4_drvdata *drvdata;
> struct resource *res = &adev->res;
> struct coresight_desc desc = { 0 };
> + struct etm_init_arg init_arg = { 0 };
>
> drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
> if (!drvdata)
> @@ -1551,7 +1584,6 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
> return PTR_ERR(base);
>
> drvdata->base = base;
> - desc.access = CSDEV_ACCESS_IOMEM(base);
>
> spin_lock_init(&drvdata->spinlock);
>
> @@ -1563,8 +1595,11 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
> if (!desc.name)
> return -ENOMEM;
>
> + init_arg.drvdata = drvdata;
> + init_arg.csa = &desc.access;
> +
> if (smp_call_function_single(drvdata->cpu,
> - etm4_init_arch_data, drvdata, 1))
> + etm4_init_arch_data, &init_arg, 1))
> dev_err(dev, "ETM arch init failed\n");
>
> if (etm4_arch_supported(drvdata->arch) == false)
> --
> 2.24.1
>