pinctrl: make struct pinfunction a pointer in struct function_desc

We currently duplicate the entire struct pinfunction object in
pinmux_generic_add_pinfunction(). While this is inevitable when the
arguments come in split through pinmux_generic_add_function(), users of
pinmux_generic_add_pinfunction() will typically pass addresses of
structures in .rodata, meaning we can try to avoid the duplication with
the help from kmemdup_const(). To that end: don't wrap the entire struct
pinfunction in struct function_desc but rather just store the address.

Tested-by: Neil Armstrong <[e-mail]>
Signed-off-by: Bartosz Golaszewski <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/pinctrl/freescale/pinctrl-imx.c

···
 	npins = grp->grp.npins;
 
 	dev_dbg(ipctl->dev, "enable function %s group %s\n",
-		func->func.name, grp->grp.name);
+		func->func->name, grp->grp.name);
 
 	for (i = 0; i < npins; i++) {
 		/*

drivers/pinctrl/mediatek/pinctrl-airoha.c

···
 		return -EINVAL;
 
 	dev_dbg(pctrl_dev->dev, "enable function %s group %s\n",
-		desc->func.name, grp->grp.name);
+		desc->func->name, grp->grp.name);
 
 	func = desc->data;
 	for (i = 0; i < func->group_size; i++) {

drivers/pinctrl/mediatek/pinctrl-moore.c

···
 		return -EINVAL;
 
 	dev_dbg(pctldev->dev, "enable function %s group %s\n",
-		func->func.name, grp->grp.name);
+		func->func->name, grp->grp.name);
 
 	for (i = 0; i < grp->grp.npins; i++) {
 		const struct mtk_pin_desc *desc;

drivers/pinctrl/pinctrl-ingenic.c

···
 		return -EINVAL;
 
 	dev_dbg(pctldev->dev, "enable function %s group %s\n",
-		func->func.name, grp->grp.name);
+		func->func->name, grp->grp.name);
 
 	mode = (uintptr_t)grp->data;
 	if (mode <= 3) {

drivers/pinctrl/pinmux.c

···
 	if (!function)
 		return NULL;
 
-	return function->func.name;
+	return function->func->name;
 }
 EXPORT_SYMBOL_GPL(pinmux_generic_get_function_name);
 
···
 			__func__, selector);
 		return -EINVAL;
 	}
-	*groups = function->func.groups;
-	*ngroups = function->func.ngroups;
+	*groups = function->func->groups;
+	*ngroups = function->func->ngroups;
 
 	return 0;
 }
···
 	if (!function)
 		return -ENOMEM;
 
-	function->func = *func;
+	/*
+	 * FIXME: It's generally a bad idea to use devres in subsystem core
+	 * code - managed interfaces are aimed at drivers - but pinctrl already
+	 * uses it all over the place so it's a larger piece of technical debt
+	 * to fix.
+	 */
+	function->func = devm_kmemdup_const(pctldev->dev, func,
+					    sizeof(*func), GFP_KERNEL);
+	if (!function->func)
+		return -ENOMEM;
+
 	function->data = data;
 
 	error = radix_tree_insert(&pctldev->pin_function_tree, selector, function);

drivers/pinctrl/pinmux.h

···
  * @data: pin controller driver specific data
  */
 struct function_desc {
-	struct pinfunction func;
+	const struct pinfunction *func;
 	void *data;
 };