Re: [PATCH v8 3/4] coresight: cti: add Qualcomm extended CTI identification and quirks

Jie Gan
2026-04-27T07:39:17Z

On 4/26/2026 5:44 PM, Yingchao Deng wrote:
> Qualcomm implements an extended variant of the ARM CoreSight CTI with a
> different register layout and vendor-specific behavior. While the
> programming model remains largely compatible, the register offsets differ
> from the standard ARM CTI and require explicit handling.
>
> Detect Qualcomm CTIs via the DEVARCH register and record this in the CTI
> driver data. Introduce a small mapping layer to translate standard CTI
> register offsets to Qualcomm-specific offsets, allowing the rest of the
> driver to use a common register access path.
>
> Additionally, handle a Qualcomm-specific quirk where the CLAIMSET
> register is incorrectly initialized to a non-zero value, which can cause
> tools or drivers to assume the component is already claimed. Clear the
> register during probe to reflect the actual unclaimed state.
>
> No functional change is intended for standard ARM CTI devices.
>
> Co-developed-by: Jinlong Mao <jinlong.mao@oss.qualcomm.com>
> Signed-off-by: Jinlong Mao <jinlong.mao@oss.qualcomm.com>
> Signed-off-by: Yingchao Deng <yingchao.deng@oss.qualcomm.com>
> ---
> drivers/hwtracing/coresight/coresight-cti-core.c | 28 +++++++++-
> drivers/hwtracing/coresight/coresight-cti.h | 4 +-
> drivers/hwtracing/coresight/qcom-cti.h | 65 ++++++++++++++++++++++++
> 3 files changed, 95 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-cti-core.c b/drivers/hwtracing/coresight/coresight-cti-core.c
> index c4cbeb64365b..b1c69a3e9b99 100644
> --- a/drivers/hwtracing/coresight/coresight-cti-core.c
> +++ b/drivers/hwtracing/coresight/coresight-cti-core.c
> @@ -21,6 +21,7 @@
>
> #include "coresight-priv.h"
> #include "coresight-cti.h"
> +#include "qcom-cti.h"
>
> /*
> * CTI devices can be associated with a PE, or be connected to CoreSight
> @@ -47,6 +48,10 @@ static void __iomem *cti_reg_addr(struct cti_drvdata *drvdata, int reg)
> u32 offset = CTI_REG_CLR_NR(reg);
> u32 nr = CTI_REG_GET_NR(reg);
>
> + /* convert to qcom specific offset */
> + if (unlikely(drvdata->is_qcom_cti))

I prefer to drop the unlikely here, let the cpu do the branch predictor.

> + offset = cti_qcom_reg_off(offset);
> +
> return drvdata->base + offset + sizeof(u32) * nr;
> }
>
> @@ -170,6 +175,9 @@ void cti_write_intack(struct device *dev, u32 ackval)
> /* DEVID[19:16] - number of CTM channels */
> #define CTI_DEVID_CTMCHANNELS(devid_val) ((int) BMVAL(devid_val, 16, 19))
>
> +/* DEVARCH[31:21] - ARCHITECT */
> +#define CTI_DEVARCH_ARCHITECT(devarch_val) ((int)BMVAL(devarch_val, 21, 31))
> +
> static int cti_set_default_config(struct device *dev,
> struct cti_drvdata *drvdata)
> {
> @@ -700,6 +708,7 @@ static int cti_probe(struct amba_device *adev, const struct amba_id *id)
> struct coresight_desc cti_desc;
> struct coresight_platform_data *pdata = NULL;
> struct resource *res = &adev->res;
> + u32 devarch;
>
> /* driver data*/
> drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
> @@ -724,6 +733,22 @@ static int cti_probe(struct amba_device *adev, const struct amba_id *id)
>
> raw_spin_lock_init(&drvdata->spinlock);
>
> + devarch = readl_relaxed(drvdata->base + CORESIGHT_DEVARCH);
> + if (CTI_DEVARCH_ARCHITECT(devarch) == ARCHITECT_QCOM) {
> + drvdata->is_qcom_cti = true;
> + /*
> + * QCOM CTI does not implement Claimtag functionality as
> + * per CoreSight specification, but its CLAIMSET register
> + * is incorrectly initialized to 0xF. This can mislead
> + * tools or drivers into thinking the component is claimed.
> + *
> + * Reset CLAIMSET to 0 to reflect that no claims are active.
> + */
> + CS_UNLOCK(drvdata->base);
> + writel_relaxed(0, drvdata->base + CORESIGHT_CLAIMSET);
> + CS_LOCK(drvdata->base);
> + }
> +
> /* initialise CTI driver config values */
> ret = cti_set_default_config(dev, drvdata);
> if (ret)
> @@ -780,7 +805,8 @@ static int cti_probe(struct amba_device *adev, const struct amba_id *id)
>
> /* all done - dec pm refcount */
> pm_runtime_put(&adev->dev);
> - dev_info(&drvdata->csdev->dev, "CTI initialized\n");
> + dev_info(&drvdata->csdev->dev,
> + "%sCTI initialized\n", drvdata->is_qcom_cti ? "QCOM " : "");
> return 0;
> }
>
> diff --git a/drivers/hwtracing/coresight/coresight-cti.h b/drivers/hwtracing/coresight/coresight-cti.h
> index dd1ba44518c4..2598601e7b93 100644
> --- a/drivers/hwtracing/coresight/coresight-cti.h
> +++ b/drivers/hwtracing/coresight/coresight-cti.h
> @@ -55,10 +55,11 @@ struct fwnode_handle;
> /*
> * CTI CSSoc 600 has a max of 32 trigger signals per direction.
> * CTI CSSoc 400 has 8 IO triggers - other CTIs can be impl def.
> + * QCOM CTI supports up to 128 trigger signals per direction.
> * Max of in and out defined in the DEVID register.
> * - pick up actual number used from .dts parameters if present.
> */
> -#define CTIINOUTEN_MAX 32
> +#define CTIINOUTEN_MAX 128
>
> /*
> * Encode CTI register offset and register index in one u32:
> @@ -188,6 +189,7 @@ struct cti_drvdata {
> raw_spinlock_t spinlock;
> struct cti_config config;
> struct list_head node;
> + bool is_qcom_cti;

missed document.

Thanks,
Jie

> };
>
> /*
> diff --git a/drivers/hwtracing/coresight/qcom-cti.h b/drivers/hwtracing/coresight/qcom-cti.h
> new file mode 100644
> index 000000000000..fd1bf07d7cb4
> --- /dev/null
> +++ b/drivers/hwtracing/coresight/qcom-cti.h
> @@ -0,0 +1,65 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
> + */
> +
> +#ifndef _CORESIGHT_QCOM_CTI_H
> +#define _CORESIGHT_QCOM_CTI_H
> +
> +#include "coresight-cti.h"
> +
> +#define ARCHITECT_QCOM 0x477
> +
> +/* CTI programming registers */
> +#define QCOM_CTIINTACK 0x020
> +#define QCOM_CTIAPPSET 0x004
> +#define QCOM_CTIAPPCLEAR 0x008
> +#define QCOM_CTIAPPPULSE 0x00C
> +#define QCOM_CTIINEN 0x400
> +#define QCOM_CTIOUTEN 0x800
> +#define QCOM_CTITRIGINSTATUS 0x040
> +#define QCOM_CTITRIGOUTSTATUS 0x060
> +#define QCOM_CTICHINSTATUS 0x080
> +#define QCOM_CTICHOUTSTATUS 0x084
> +#define QCOM_CTIGATE 0x088
> +#define QCOM_ASICCTL 0x08C
> +/* Integration test registers */
> +#define QCOM_ITCHINACK 0xE70
> +#define QCOM_ITTRIGINACK 0xE80
> +#define QCOM_ITCHOUT 0xE74
> +#define QCOM_ITTRIGOUT 0xEA0
> +#define QCOM_ITCHOUTACK 0xE78
> +#define QCOM_ITTRIGOUTACK 0xEC0
> +#define QCOM_ITCHIN 0xE7C
> +#define QCOM_ITTRIGIN 0xEE0
> +
> +static noinline u32 cti_qcom_reg_off(u32 offset)
> +{
> + switch (offset) {
> + case CTIINTACK: return QCOM_CTIINTACK;
> + case CTIAPPSET: return QCOM_CTIAPPSET;
> + case CTIAPPCLEAR: return QCOM_CTIAPPCLEAR;
> + case CTIAPPPULSE: return QCOM_CTIAPPPULSE;
> + case CTIINEN: return QCOM_CTIINEN;
> + case CTIOUTEN: return QCOM_CTIOUTEN;
> + case CTITRIGINSTATUS: return QCOM_CTITRIGINSTATUS;
> + case CTITRIGOUTSTATUS: return QCOM_CTITRIGOUTSTATUS;
> + case CTICHINSTATUS: return QCOM_CTICHINSTATUS;
> + case CTICHOUTSTATUS: return QCOM_CTICHOUTSTATUS;
> + case CTIGATE: return QCOM_CTIGATE;
> + case ASICCTL: return QCOM_ASICCTL;
> + case ITCHINACK: return QCOM_ITCHINACK;
> + case ITTRIGINACK: return QCOM_ITTRIGINACK;
> + case ITCHOUT: return QCOM_ITCHOUT;
> + case ITTRIGOUT: return QCOM_ITTRIGOUT;
> + case ITCHOUTACK: return QCOM_ITCHOUTACK;
> + case ITTRIGOUTACK: return QCOM_ITTRIGOUTACK;
> + case ITCHIN: return QCOM_ITCHIN;
> + case ITTRIGIN: return QCOM_ITTRIGIN;
> +
> + default:
> + return offset;
> + }
> +}
> +
> +#endif /* _CORESIGHT_QCOM_CTI_H */
>