Re: [PM-WIP-OPP][PATCH 3/4] omap: pm: opp: add ability to store data per opp

[Felipe Balbi <felipe.balbi@nokia.com>]

hi,

On Thu, Mar 18, 2010 at 07:44:50PM +0100, ext Nishanth Menon wrote:
>+int opp_store_data(struct omap_opp *opp, char *name, void *data)
>+{
>+	return -EINVAL;

Would -ENODATA fit better ??

>diff --git a/arch/arm/plat-omap/opp.c b/arch/arm/plat-omap/opp.c
>index bb8120e..15f6f7c 100644
>--- a/arch/arm/plat-omap/opp.c
>+++ b/arch/arm/plat-omap/opp.c
>@@ -14,12 +14,19 @@
> #include <linux/errno.h>
> #include <linux/err.h>
> #include <linux/init.h>
>+#include <linux/list.h>
> #include <linux/slab.h>
> #include <linux/cpufreq.h>
>
> #include <plat/opp_twl_tps.h>
> #include <plat/opp.h>
>
>+struct omap_opp_data {
>+	char *name;
>+	void *data;
>+	struct list_head list;
>+};
>+
> /**
>  * struct omap_opp - OMAP OPP description structure
>  * @enabled:	true/false - marking this OPP as enabled/disabled
>@@ -37,6 +44,7 @@ struct omap_opp {
> 	unsigned long rate;
> 	unsigned long u_volt;
> 	u8 opp_id;
>+	struct list_head data_list;
> };
>
> /*
>@@ -218,6 +226,7 @@ static void omap_opp_populate(struct omap_opp *opp,
> 	opp->rate = opp_def->freq;
> 	opp->enabled = opp_def->enabled;
> 	opp->u_volt = opp_def->u_volt;
>+	INIT_LIST_HEAD(&opp->data_list);
> }
>
> int opp_add(enum opp_t opp_type, const struct omap_opp_def *opp_def)
>@@ -352,6 +361,63 @@ int opp_disable(struct omap_opp *opp)
> 	return 0;
> }
>
>+void *opp_get_data(struct omap_opp *opp, char *name)
>+{
>+	void *data = ERR_PTR(-EINVAL);
>+	struct omap_opp_data *tmp;
>+
>+	if (unlikely(!opp || !name))
>+		return ERR_PTR(-EINVAL);
>+
>+	list_for_each_entry(tmp, &opp->data_list, list)
>+		if (!strcmp(name, tmp->name)) {
>+			data = tmp->data;
>+			break;
>+		}
>+	return data;
>+}
>+
>+int opp_store_data(struct omap_opp *opp, char *name, void *data)
>+{
>+	struct omap_opp_data *new;
>+	if (unlikely(!opp || !name))
>+		return -EINVAL;
>+	/* NAK to double registration */
>+	if (unlikely(!IS_ERR(opp_get_data(opp, name))))
>+		return -EINVAL;
>+
>+	new = kmalloc(sizeof(struct omap_opp), GFP_KERNEL);
>+	if (!new)
>+		return -ENOMEM;
>+	new->name = kmalloc(strlen(name) + 1, GFP_KERNEL);
>+	if (!new->name) {
>+		kfree(new);
>+		return -ENOMEM;
>+	}
>+	new->data = data;
>+	strcpy(new->name, name);
>+	INIT_LIST_HEAD(&new->list);
>+	list_add(&new->list, &opp->data_list);
>+	return 0;
>+}

will you really want to add several data entries there ? I don't see the 
point. Maybe I'm missing something.

I like the idea of having a void * to allow you to store anything there. 
But generally that's a 1 - 1 relation:

1 device/bus/(in this case) opp - 1 data.

by doing that, the API will look like 
dev_set_drvdata()/dev_get_drvdata() and could be implemented simply as:

void opp_set_data(struct omap_opp *opp, void *data)
{
	opp->data = data;

	return 0;
}

void *opp_get_data(struct omap_opp *opp)
{
	return opp->data;
}

-- 
balbi