On Fri, 2015-03-20 at 19:29 +0200, Alexander Shishkin wrote:
> Global Trace Hub (GTH) is the central component of Intel TH architecture;
> it carries out switching between the trace sources and trace outputs, can
> enable/disable tracing, perform STP encoding, internal buffering, control
> backpressure from outputs to sources and so on.
trivia:
> diff --git a/drivers/hwtracing/intel_th/gth.c
> b/drivers/hwtracing/intel_th/gth.c
> +struct gth_output {
> + struct gth_device *gth;
> + struct intel_th_output *output;
> + unsigned int index;
> + unsigned int port_type;
> + unsigned long master[TH_CONFIGURABLE_MASTERS + 1 /
> + BITS_PER_LONG];
DECLARE_BITMAP(master, TH_CONFIGURABLE_MASTERS+ 1); ?
> +};
> +
> +/**
> + * struct gth_device - GTH device
> + * @dev: driver core's device
> + * @base: register window base address
> + * @output_group: attributes describing output ports
> + * @master_group: attributes describing master assignments
> + * @output: output ports
> + * @master: master/output port assignments
> + * @gth_lock: serializes accesses to GTH bits
> + */
> +struct gth_device {
> + struct device *dev;
> + void __iomem *base;
> +
> + struct attribute_group output_group;
> + struct attribute_group master_group;
> + struct gth_output output[TH_POSSIBLE_OUTPUTS];
> + signed char master[TH_CONFIGURABLE_MASTERS + 1];
why signed?
[]
> +#define OUTPUT_PARM(_name, _mask, _r, _w) \
> + [TH_OUTPUT_PARM(_name)] = { .name = __stringify(_name), \
> + .mask = (_mask), \
> + .readable = (_r), \
> + .writable = (_w) }
> +
> +static struct output_parm {
const
> + const char *name;
> + unsigned int mask;
> + unsigned int readable : 1,
> + writable : 1;
> +} output_parms[] = {
> + OUTPUT_PARM(port, 0x7, 1, 0),
> + OUTPUT_PARM(null, BIT(3), 1, 1),
> + OUTPUT_PARM(drop, BIT(4), 1, 1),
> + OUTPUT_PARM(reset, BIT(5), 1, 0),
> + OUTPUT_PARM(flush, BIT(7), 0, 1),
> +};
[]
> +static int intel_th_master_attributes(struct gth_device *gth)
> +{
> + struct master_attribute *master_attrs;
> + struct attribute **attrs;
> + int i, nattrs = TH_CONFIGURABLE_MASTERS + 2;
> +
> + attrs = devm_kzalloc(gth->dev, sizeof(void *) * nattrs, GFP_KERNEL);
> + if (!attrs)
> + return -ENOMEM;
> +
> + master_attrs = devm_kzalloc(gth->dev,
> + sizeof(struct master_attribute) * nattrs,
> + GFP_KERNEL);
devm_kcalloc
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