[0/3] clk: keystone: a few TI sci-clk improvements

Hi,

Patch 1 & 2 introduce a new DT flag for parsing the clock data from devicetree
instead of querying everything from firmware. The purpose of this change
is to improve boot time, it can be seen to give ~2s improvement in certain
setups. If adding a new DT flag for this is not acceptable, a kernel command
line parameter could be introduced instead, or even a new Kconfig option.
I voted for the DT flag for now as that seems to be the most versatile
solution.

Patch 3 shortens the kernel registered clock names, currently for am65x
they are of the form:

interconnect@100000:interconnect@28380000:interconnect@42040000:dmsc:clocks:11:1
0

After this patch the same clock name is cut down to:

clocks:11:10

This makes the debugfs interface much more readable in addition to some
memory savings.

-Tero

--
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

On Tue, Jan 08, 2019 at 03:30:22PM +0200, Tero Kristo wrote:
> Currently the sci-clk driver queries clock data from the firmware, which
> can be pretty slow operation in certain cases. Add an option for the
> driver to probe the available clocks from DT also, in this case the
> number of clocks probed from firmware gets cut down drastically. To
> enable the feature, a new flag ti,scan-clocks-from-dt can be added
> under the clock provider node.
> 
> Signed-off-by: Tero Kristo <t-kristo@ti.com>
> Tested-by: Andreas Dannenberg <dannenberg@ti.com>
> ---
>  drivers/clk/keystone/sci-clk.c | 188 ++++++++++++++++++++++++++++++++++-------
>  1 file changed, 159 insertions(+), 29 deletions(-)


> +static int ti_sci_scan_clocks_from_dt(struct sci_clk_provider *provider)
> +{
> +	struct device *dev = provider->dev;
> +	struct device_node *np = NULL;
> +	int ret;
> +	int index;
> +	struct of_phandle_args args;
> +	struct list_head clks;
> +	struct sci_clk *sci_clk, *prev;
> +	int num_clks = 0;
> +	int num_parents;
> +	int clk_id;
> +
> +	INIT_LIST_HEAD(&clks);
> +
> +	while (1) {
> +		np = of_find_node_with_property(np, "clocks");
> +		if (!np)
> +			break;

for_each_node_with_property

> +
> +		index = 0;
> +
> +		do {
> +			ret = of_parse_phandle_with_args(np, "clocks",
> +							 "#clock-cells", index,
> +							 &args);
> +			if (ret)
> +				break;

of_for_each_phandle can be used here. And then of_phandle_iterator_args 
will get the args.

> +
> +			if (args.args_count == 2 && args.np == dev->of_node) {

dtc will warn if the # of cells are wrong, so that's probably redundant.

Invert the if and save a level of indentation.

> +				sci_clk = devm_kzalloc(dev, sizeof(*sci_clk),
> +						       GFP_KERNEL);
> +				if (!sci_clk)
> +					return -ENOMEM;
> +
> +				sci_clk->dev_id = args.args[0];
> +				sci_clk->clk_id = args.args[1];
> +				sci_clk->provider = provider;
> +				provider->ops->
> +					get_num_parents(provider->sci,
> +							sci_clk->dev_id,
> +							sci_clk->clk_id,
> +							&sci_clk->num_parents);
> +				list_add_tail(&sci_clk->node, &clks);
> +
> +				num_clks++;
> +
> +				num_parents = sci_clk->num_parents;
> +				if (num_parents == 1)
> +					num_parents = 0;
> +
> +				clk_id = args.args[1] + 1;
> +
> +				while (num_parents--) {
> +					sci_clk = devm_kzalloc(dev,
> +							       sizeof(*sci_clk),
> +							       GFP_KERNEL);
> +					if (!sci_clk)
> +						return -ENOMEM;
> +					sci_clk->dev_id = args.args[0];
> +					sci_clk->clk_id = clk_id++;
> +					sci_clk->provider = provider;
> +					list_add_tail(&sci_clk->node, &clks);
> +
> +					num_clks++;
> +				}
> +			}
> +
> +			index++;
> +		} while (args.np);
> +	}
> +
> +	list_sort(NULL, &clks, _cmp_sci_clk_list);
> +
> +	provider->clocks = devm_kmalloc_array(dev, num_clks, sizeof(sci_clk),
> +					      GFP_KERNEL);
> +	if (!provider->clocks)
> +		return -ENOMEM;
> +
> +	num_clks = 0;
> +	prev = NULL;
> +
> +	list_for_each_entry(sci_clk, &clks, node) {
> +		if (prev && prev->dev_id == sci_clk->dev_id &&
> +		    prev->clk_id == sci_clk->clk_id)
> +			continue;
> +
> +		provider->clocks[num_clks++] = sci_clk;
> +		prev = sci_clk;
> +	}
> +
> +	provider->num_clocks = num_clks;
> +
> +	return 0;
> +}