Re: [PATCH v3 06/11] coresight-tpdm: Add node to set dsb programming mode

Suzuki K Poulose
2023-03-23T14:56:03Z

On 23/03/2023 06:04, Tao Zhang wrote:
> Add node to set and show programming mode for TPDM DSB subunit.
> Once the DSB programming mode is set, it will be written to the
> register DSB_CR. Bit[10:9] of the DSB_CR register is used to set
> the DSB test mode.
>
> Signed-off-by: Tao Zhang <quic_taozha@quicinc.com>
> ---
> .../ABI/testing/sysfs-bus-coresight-devices-tpdm | 10 ++++
> drivers/hwtracing/coresight/coresight-tpdm.c | 62 ++++++++++++++++++++++
> drivers/hwtracing/coresight/coresight-tpdm.h | 13 +++++
> 3 files changed, 85 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
> index 27ce681..f13e282 100644
> --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
> +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
> @@ -35,3 +35,13 @@ Description:
> Accepts only one of the 2 values - 0 or 1.
> 0 : Set the DSB trigger type to false
> 1 : Set the DSB trigger type to true
> +
> +What: /sys/bus/coresight/devices/<tpdm-name>/dsb_mode
> +Date: March 2023
> +KernelVersion 6.3
> +Contact: Jinlong Mao (QUIC) <quic_jinlmao@quicinc.com>, Tao Zhang (QUIC) <quic_taozha@quicinc.com>
> +Description:
> + (Write) Set the mode of DSB tpdm. Read the mode of DSB
> + tpdm.
> +
> + Accepts the value needs to be greater than 0.

Please could you document the values ?

> diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c b/drivers/hwtracing/coresight/coresight-tpdm.c
> index e28cf10..8cd822f 100644
> --- a/drivers/hwtracing/coresight/coresight-tpdm.c
> +++ b/drivers/hwtracing/coresight/coresight-tpdm.c
> @@ -4,6 +4,7 @@
> */
>
> #include <linux/amba/bus.h>
> +#include <linux/bitfield.h>
> #include <linux/bitmap.h>
> #include <linux/coresight.h>
> #include <linux/coresight-pmu.h>
> @@ -51,6 +52,32 @@ static int tpdm_init_datasets(struct tpdm_drvdata *drvdata)
> return 0;
> }
>
> +static void set_dsb_cycacc_mode(struct tpdm_drvdata *drvdata, u32 *val)
> +{
> + u32 mode;
> +
> + mode = TPDM_DSB_MODE_CYCACC(drvdata->dsb->mode);
> + *val &= ~TPDM_DSB_TEST_MODE;
> + *val |= FIELD_PREP(TPDM_DSB_TEST_MODE, mode);
> +}
> +
> +static void set_dsb_hpsel_mode(struct tpdm_drvdata *drvdata, u32 *val)
> +{
> + u32 mode;
> +
> + mode = TPDM_DSB_MODE_HPBYTESEL(drvdata->dsb->mode);
> + *val &= ~TPDM_DSB_HPSEL;
> + *val |= FIELD_PREP(TPDM_DSB_HPSEL, mode);
> +}
> +
> +static void set_dsb_perf_mode(struct tpdm_drvdata *drvdata, u32 *val)
> +{
> + if (drvdata->dsb->mode & TPDM_DSB_MODE_PERF)
> + *val |= TPDM_DSB_CR_MODE;
> + else
> + *val &= ~TPDM_DSB_CR_MODE;
> +}
> +
> static void set_trigger_type(struct tpdm_drvdata *drvdata, u32 *val)
> {
> if (drvdata->dsb->trig_type)
> @@ -72,6 +99,12 @@ static void tpdm_enable_dsb(struct tpdm_drvdata *drvdata)
> writel_relaxed(val, drvdata->base + TPDM_DSB_TIER);
>
> val = readl_relaxed(drvdata->base + TPDM_DSB_CR);
> + /* Set the cycle accurate mode */
> + set_dsb_cycacc_mode(drvdata, &val);
> + /* Set the byte lane for high-performance mode */
> + set_dsb_hpsel_mode(drvdata, &val);
> + /* Set the performance mode */
> + set_dsb_perf_mode(drvdata, &val);
> /* Set trigger type */
> set_trigger_type(drvdata, &val);
> /* Set the enable bit of DSB control register to 1 */
> @@ -250,6 +283,34 @@ static struct attribute_group tpdm_attr_grp = {
> .attrs = tpdm_attrs,
> };
>
> +static ssize_t dsb_mode_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
> +
> + return sysfs_emit(buf, "%lx\n",
> + (unsigned long)drvdata->dsb->mode);
> +}
> +
> +static ssize_t dsb_mode_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf,
> + size_t size)
> +{
> + struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
> + unsigned long val;
> +
> + if ((kstrtoul(buf, 0, &val)) || val < 0)
> + return -EINVAL;
> +
> + spin_lock(&drvdata->spinlock);
> + drvdata->dsb->mode = val & TPDM_MODE_ALL;
> + spin_unlock(&drvdata->spinlock);
> + return size;
> +}
> +static DEVICE_ATTR_RW(dsb_mode);
> +
> static ssize_t dsb_trig_type_show(struct device *dev,
> struct device_attribute *attr,
> char *buf)
> @@ -321,6 +382,7 @@ static ssize_t dsb_trig_ts_store(struct device *dev,
> static DEVICE_ATTR_RW(dsb_trig_ts);
>
> static struct attribute *tpdm_dsb_attrs[] = {
> + &dev_attr_dsb_mode.attr,
> &dev_attr_dsb_trig_ts.attr,
> &dev_attr_dsb_trig_type.attr,
> NULL,
> diff --git a/drivers/hwtracing/coresight/coresight-tpdm.h b/drivers/hwtracing/coresight/coresight-tpdm.h
> index 68f33bd..8fee562 100644
> --- a/drivers/hwtracing/coresight/coresight-tpdm.h
> +++ b/drivers/hwtracing/coresight/coresight-tpdm.h
> @@ -15,11 +15,22 @@
>
> /* Enable bit for DSB subunit */
> #define TPDM_DSB_CR_ENA BIT(0)
> +/* Enable bit for DSB subunit perfmance mode */
> +#define TPDM_DSB_CR_MODE BIT(1)
> /* Enable bit for DSB subunit trigger type */
> #define TPDM_DSB_CR_TRIG_TYPE BIT(12)
> +
> /* Enable bit for DSB subunit trigger timestamp */
> #define TPDM_DSB_TIER_XTRIG_TSENAB BIT(1)
>
> +/* DSB programming modes */
> +#define TPDM_DSB_MODE_CYCACC(val) (val & GENMASK(2, 0))

What do the values for the CYCACC mode mean ?

> +#define TPDM_DSB_MODE_PERF BIT(3)
> +#define TPDM_DSB_MODE_HPBYTESEL(val) (val & GENMASK(8, 4))
> +#define TPDM_MODE_ALL (0xFFFFFFF)
> +#define TPDM_DSB_TEST_MODE GENMASK(11, 9)
> +#define TPDM_DSB_HPSEL GENMASK(6, 2)

Again what do the values mean ? Even if the kernel doesn't use them
it would be good to document it.

Suzuki

> +
> /* TPDM integration test registers */
> #define TPDM_ITATBCNTRL (0xEF0)
> #define TPDM_ITCNTRL (0xF00)
> @@ -48,10 +59,12 @@
>
> /**
> * struct dsb_dataset - specifics associated to dsb dataset
> + * @mode: DSB programming mode
> * @trig_ts: Enable/Disable trigger timestamp.
> * @trig_type: Enable/Disable trigger type.
> */
> struct dsb_dataset {
> + u32 mode;
> bool trig_ts;
> bool trig_type;
> };