[Pdbg] [RFC 07/12] libpdbg: Rework dt_new_node()

[Alistair Popple]

I think it makes the code a bit easier to follow anyway, so if you think it 
will be useful in future and agree that it doesn't make any functional changes 
then I am happy to take it as part of this series.

- Alistair

On Tuesday, 20 August 2019 2:00:51 PM AEST Amitay Isaacs wrote:
> We definitely need a function to create a new node without assigning
> the driver (or initializing the hw_unit part of the structure).
> 
> We also need to separate the assignment of hw drivers to a target.  So
> in the first pass, we simply parse fdt and create device tree "node"
> without assigning any driver.  And in the second pass of the device
> tree, we can assign the drivers.  This will be helpful later when we
> want do dynamically insert common sub-trees.
> 
> Question is would you like to do that as part of this series?
> 
> On Tue, 2019-08-06 at 11:37 +1000, Alistair Popple wrote:
> > Simplify the control logic for dt_new_node() by splitting out the
> > initialisation from the HW unit. Should be no functional change.
> > 
> > Signed-off-by: Alistair Popple <alistair at popple.id.au>
> > ---
> >  libpdbg/device.c | 89 +++++++++++++++++++++++++++++-----------------
> > --
> >  1 file changed, 54 insertions(+), 35 deletions(-)
> > 
> > diff --git a/libpdbg/device.c b/libpdbg/device.c
> > index 7a913b2..21ec3a3 100644
> > --- a/libpdbg/device.c
> > +++ b/libpdbg/device.c
> > @@ -65,60 +65,79 @@ static const char *take_name(const char *name)
> >  	return name;
> >  }
> >  
> > -static struct pdbg_target *dt_new_node(const char *name, const void
> > *fdt, int node_offset)
> > +/* Adds information representing an actual target */
> > +static struct pdbg_target *pdbg_target_new(const void *fdt, int
> > node_offset)
> >  {
> > +	struct pdbg_target *target;
> > +	struct pdbg_target_class *target_class;
> >  	const struct hw_unit_info *hw_info = NULL;
> >  	const struct fdt_property *prop;
> > -	struct pdbg_target *node;
> > -	size_t size = sizeof(*node);
> > -
> > -	if (fdt) {
> > -		prop = fdt_get_property(fdt, node_offset, "compatible",
> > NULL);
> > -		if (prop) {
> > -			int i, prop_len = fdt32_to_cpu(prop->len);
> > -
> > -			/*
> > -			 * If I understand correctly, the property we
> > have
> > -			 * here can be a stringlist with a few
> > compatible
> > -			 * strings
> > -			 */
> > -			i = 0;
> > -			while (i < prop_len) {
> > -				hw_info =
> > pdbg_hwunit_find_compatible(&prop->data[i]);
> > -				if (hw_info) {
> > -					size = hw_info->size;
> > -					break;
> > -				}
> > -
> > -				i += strlen(&prop->data[i]) + 1;
> > +	size_t size;
> > +
> > +	prop = fdt_get_property(fdt, node_offset, "compatible", NULL);
> > +	if (prop) {
> > +		int i, prop_len = fdt32_to_cpu(prop->len);
> > +
> > +		/*
> > +		 * If I understand correctly, the property we have
> > +		 * here can be a stringlist with a few compatible
> > +		 * strings
> > +		 */
> > +		i = 0;
> > +		while (i < prop_len) {
> > +			hw_info = pdbg_hwunit_find_compatible(&prop-
> > >data[i]);
> > +			if (hw_info) {
> > +				size = hw_info->size;
> > +				break;
> >  			}
> > +
> > +			i += strlen(&prop->data[i]) + 1;
> >  		}
> >  	}
> >  
> > -	node = calloc(1, size);
> > -	if (!node) {
> > +	if (!hw_info)
> > +		/* Couldn't find anything implementing this target */
> > +		return NULL;
> > +
> > +	target = calloc(1, size);
> > +	if (!target) {
> >  		prerror("Failed to allocate node\n");
> >  		abort();
> >  	}
> >  
> > -	if (hw_info) {
> > -		struct pdbg_target_class *target_class;
> > +	/* hw_info->hw_unit points to a per-target struct type. This
> > +	 * works because the first member in the per-target struct is
> > +	 * guaranteed to be the struct pdbg_target (see the comment
> > +	 * above DECLARE_HW_UNIT). */
> > +	memcpy(target, hw_info->hw_unit, size);
> > +	target_class = get_target_class(target->class);
> > +	list_add_tail(&target_class->targets, &target->class_link);
> > +
> > +	return target;
> > +}
> >  
> > -		/* hw_info->hw_unit points to a per-target struct type.
> > This
> > -		 * works because the first member in the per-target
> > struct is
> > -		 * guaranteed to be the struct pdbg_target (see the
> > comment
> > -		 * above DECLARE_HW_UNIT). */
> > -		memcpy(node, hw_info->hw_unit, size);
> > -		target_class = get_target_class(node->class);
> > -		list_add_tail(&target_class->targets, &node-
> > >class_link);
> > +static struct pdbg_target *dt_new_node(const char *name, const void
> > *fdt, int node_offset)
> > +{
> > +	struct pdbg_target *node = NULL;
> > +	size_t size = sizeof(*node);
> > +
> > +	if (fdt)
> > +		node = pdbg_target_new(fdt, node_offset);
> > +
> > +	if (!node)
> > +		node = calloc(1, size);
> > +
> > +	if (!node) {
> > +		prerror("Failed to allocate node\n");
> > +		abort();
> >  	}
> >  
> >  	node->dn_name = take_name(name);
> >  	node->parent = NULL;
> >  	list_head_init(&node->properties);
> >  	list_head_init(&node->children);
> > -	/* FIXME: locking? */
> >  	node->phandle = ++last_phandle;
> > +
> >  	return node;
> >  }
> >  
> 
> Amitay.
>