[Skiboot] [PATCH V3] sensors: dts: Assert special wakeup on idle cores while reading temperature

[Stewart Smith]

Shilpasri G Bhat <shilpa.bhat at linux.vnet.ibm.com> writes:
> In P9, when a core enters a stop state, its clocks will be stopped
> to save power and hence we will not be able to perform a scom
> operation to read the DTS temperature sensor.  Hence, assert
> a special wakeup on cores that have entered a stop state in order to
> successfully complete the scom operation.
>
> Signed-off-by: Shilpasri G Bhat <shilpa.bhat at linux.vnet.ibm.com>
> ---
> Changes from V2:
> - Rebase on msater to use dctl_{set/clear}_special_wakeup()
>
>  core/direct-controls.c |  4 +--
>  core/sensor.c          |  2 +-
>  hw/dts.c               | 83 +++++++++++++++++++++++++++++++++++++++++---------
>  include/cpu.h          |  3 ++
>  include/dts.h          |  2 +-
>  5 files changed, 76 insertions(+), 18 deletions(-)
>
> diff --git a/core/direct-controls.c b/core/direct-controls.c
> index 9acdab5..1f44bc7 100644
> --- a/core/direct-controls.c
> +++ b/core/direct-controls.c
> @@ -217,7 +217,7 @@ static int p9_sreset_thread(struct cpu_thread *cpu)
>  	return 0;
>  }
>  
> -static int dctl_set_special_wakeup(struct cpu_thread *t)
> +int dctl_set_special_wakeup(struct cpu_thread *t)
>  {
>  	struct cpu_thread *c = t->primary;
>  	int rc = OPAL_SUCCESS;
> @@ -235,7 +235,7 @@ static int dctl_set_special_wakeup(struct cpu_thread *t)
>  	return rc;
>  }
>  
> -static int dctl_clear_special_wakeup(struct cpu_thread *t)
> +int dctl_clear_special_wakeup(struct cpu_thread *t)
>  {
>  	struct cpu_thread *c = t->primary;
>  	int rc = OPAL_SUCCESS;
> diff --git a/core/sensor.c b/core/sensor.c
> index 57b21bc..0e2a5ca 100644
> --- a/core/sensor.c
> +++ b/core/sensor.c
> @@ -28,7 +28,7 @@ static int64_t opal_sensor_read(uint32_t sensor_hndl, int token,
>  {
>  	switch (sensor_get_family(sensor_hndl)) {
>  	case SENSOR_DTS:
> -		return dts_sensor_read(sensor_hndl, sensor_data);
> +		return dts_sensor_read(sensor_hndl, token, sensor_data);
>  	case SENSOR_OCC:
>  		return occ_sensor_read(sensor_hndl, sensor_data);
>  	default:
> diff --git a/hw/dts.c b/hw/dts.c
> index a10df58..2fda769 100644
> --- a/hw/dts.c
> +++ b/hw/dts.c
> @@ -20,6 +20,9 @@
>  #include <dts.h>
>  #include <skiboot.h>
>  #include <opal-api.h>
> +#include <opal-msg.h>
> +#include <timer.h>
> +#include <timebase.h>
>  
>  struct dts {
>  	uint8_t		valid;
> @@ -27,6 +30,14 @@ struct dts {
>  	int16_t		temp;
>  };
>  
> +/*
> + * Attributes for the core temperature sensor
> + */
> +enum {
> +	SENSOR_DTS_ATTR_TEMP_MAX,
> +	SENSOR_DTS_ATTR_TEMP_TRIP
> +};
> +
>  /* Different sensor locations */
>  #define P7_CT_ZONE_LSU	0
>  #define P7_CT_ZONE_ISU	1
> @@ -196,7 +207,7 @@ static int dts_read_core_temp_p8(uint32_t pir, struct dts *dts)
>   * Returns the temperature as the max of all zones and a global trip
>   * attribute.
>   */
> -static int dts_read_core_temp_p9(uint32_t pir, struct dts *dts)
> +static int _dts_read_core_temp_p9(u32 pir, struct dts *dts)
>  {
>  	int32_t chip_id = pir_to_chip_id(pir);
>  	int32_t core = pir_to_core_id(pir);
> @@ -225,7 +236,52 @@ static int dts_read_core_temp_p9(uint32_t pir, struct dts *dts)
>  	return 0;
>  }
>  
> -static int dts_read_core_temp(uint32_t pir, struct dts *dts)
> +static struct timer dts_timer;
> +static struct dts_async_data {
> +	struct cpu_thread *cpu;
> +	u32 *sensor_data;
> +	int token;
> +	u8 attr;
> +} dts_async_data;

this means that only one concurrent request can be going on.

We should *not* put that limit here (where we would silently overwrite
previous attempts and end up somewhere really weird)..

Please fix.

-- 
Stewart Smith
OPAL Architect, IBM.