linux/drivers/pinctrl/devicetree.c
Thierry Reding 62a6bc3a1e driver: core: Allow subsystems to continue deferring probe
Some subsystems, such as pinctrl, allow continuing to defer probe
indefinitely. This is useful for devices that depend on resources
provided by devices that are only probed after the init stage.

One example of this can be seen on Tegra, where the DPAUX hardware
contains pinmuxing controls for pins that it shares with an I2C
controller. The I2C controller is typically used for communication
with a monitor over HDMI (DDC). However, other instances of the I2C
controller are used to access system critical components, such as a
PMIC. The I2C controller driver will therefore usually be a builtin
driver, whereas the DPAUX driver is part of the display driver that
is loaded from a module to avoid bloating the kernel image with all
of the DRM/KMS subsystem.

In this particular case the pins used by this I2C/DDC controller
become accessible very late in the boot process. However, since the
controller is only used in conjunction with display, that's not an
issue.

Unfortunately the driver core currently outputs a warning message
when a device fails to get the pinctrl before the end of the init
stage. That can be confusing for the user because it may sound like
an unwanted error occurred, whereas it's really an expected and
harmless situation.

In order to eliminate this warning, this patch allows callers of the
driver_deferred_probe_check_state() helper to specify that they want
to continue deferring probe, regardless of whether we're past the
init stage or not. All of the callers of that function are updated
for the new signature, but only the pinctrl subsystem passes a true
value in the new persist parameter if appropriate.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20190621151725.20414-1-thierry.reding@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-07-03 21:28:20 +02:00

416 lines
11 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Device tree integration for the pin control subsystem
*
* Copyright (C) 2012 NVIDIA CORPORATION. All rights reserved.
*/
#include <linux/device.h>
#include <linux/of.h>
#include <linux/pinctrl/pinctrl.h>
#include <linux/slab.h>
#include "core.h"
#include "devicetree.h"
/**
* struct pinctrl_dt_map - mapping table chunk parsed from device tree
* @node: list node for struct pinctrl's @dt_maps field
* @pctldev: the pin controller that allocated this struct, and will free it
* @maps: the mapping table entries
*/
struct pinctrl_dt_map {
struct list_head node;
struct pinctrl_dev *pctldev;
struct pinctrl_map *map;
unsigned num_maps;
};
static void dt_free_map(struct pinctrl_dev *pctldev,
struct pinctrl_map *map, unsigned num_maps)
{
if (pctldev) {
const struct pinctrl_ops *ops = pctldev->desc->pctlops;
if (ops->dt_free_map)
ops->dt_free_map(pctldev, map, num_maps);
} else {
/* There is no pctldev for PIN_MAP_TYPE_DUMMY_STATE */
kfree(map);
}
}
void pinctrl_dt_free_maps(struct pinctrl *p)
{
struct pinctrl_dt_map *dt_map, *n1;
list_for_each_entry_safe(dt_map, n1, &p->dt_maps, node) {
pinctrl_unregister_map(dt_map->map);
list_del(&dt_map->node);
dt_free_map(dt_map->pctldev, dt_map->map,
dt_map->num_maps);
kfree(dt_map);
}
of_node_put(p->dev->of_node);
}
static int dt_remember_or_free_map(struct pinctrl *p, const char *statename,
struct pinctrl_dev *pctldev,
struct pinctrl_map *map, unsigned num_maps)
{
int i;
struct pinctrl_dt_map *dt_map;
/* Initialize common mapping table entry fields */
for (i = 0; i < num_maps; i++) {
map[i].dev_name = dev_name(p->dev);
map[i].name = statename;
if (pctldev)
map[i].ctrl_dev_name = dev_name(pctldev->dev);
}
/* Remember the converted mapping table entries */
dt_map = kzalloc(sizeof(*dt_map), GFP_KERNEL);
if (!dt_map) {
dt_free_map(pctldev, map, num_maps);
return -ENOMEM;
}
dt_map->pctldev = pctldev;
dt_map->map = map;
dt_map->num_maps = num_maps;
list_add_tail(&dt_map->node, &p->dt_maps);
return pinctrl_register_map(map, num_maps, false);
}
struct pinctrl_dev *of_pinctrl_get(struct device_node *np)
{
return get_pinctrl_dev_from_of_node(np);
}
static int dt_to_map_one_config(struct pinctrl *p,
struct pinctrl_dev *hog_pctldev,
const char *statename,
struct device_node *np_config)
{
struct pinctrl_dev *pctldev = NULL;
struct device_node *np_pctldev;
const struct pinctrl_ops *ops;
int ret;
struct pinctrl_map *map;
unsigned num_maps;
bool allow_default = false;
/* Find the pin controller containing np_config */
np_pctldev = of_node_get(np_config);
for (;;) {
if (!allow_default)
allow_default = of_property_read_bool(np_pctldev,
"pinctrl-use-default");
np_pctldev = of_get_next_parent(np_pctldev);
if (!np_pctldev || of_node_is_root(np_pctldev)) {
of_node_put(np_pctldev);
/* keep deferring if modules are enabled unless we've timed out */
if (IS_ENABLED(CONFIG_MODULES) && !allow_default)
return driver_deferred_probe_check_state_continue(p->dev);
return driver_deferred_probe_check_state(p->dev);
}
/* If we're creating a hog we can use the passed pctldev */
if (hog_pctldev && (np_pctldev == p->dev->of_node)) {
pctldev = hog_pctldev;
break;
}
pctldev = get_pinctrl_dev_from_of_node(np_pctldev);
if (pctldev)
break;
/* Do not defer probing of hogs (circular loop) */
if (np_pctldev == p->dev->of_node) {
of_node_put(np_pctldev);
return -ENODEV;
}
}
of_node_put(np_pctldev);
/*
* Call pinctrl driver to parse device tree node, and
* generate mapping table entries
*/
ops = pctldev->desc->pctlops;
if (!ops->dt_node_to_map) {
dev_err(p->dev, "pctldev %s doesn't support DT\n",
dev_name(pctldev->dev));
return -ENODEV;
}
ret = ops->dt_node_to_map(pctldev, np_config, &map, &num_maps);
if (ret < 0)
return ret;
/* Stash the mapping table chunk away for later use */
return dt_remember_or_free_map(p, statename, pctldev, map, num_maps);
}
static int dt_remember_dummy_state(struct pinctrl *p, const char *statename)
{
struct pinctrl_map *map;
map = kzalloc(sizeof(*map), GFP_KERNEL);
if (!map)
return -ENOMEM;
/* There is no pctldev for PIN_MAP_TYPE_DUMMY_STATE */
map->type = PIN_MAP_TYPE_DUMMY_STATE;
return dt_remember_or_free_map(p, statename, NULL, map, 1);
}
bool pinctrl_dt_has_hogs(struct pinctrl_dev *pctldev)
{
struct device_node *np;
struct property *prop;
int size;
np = pctldev->dev->of_node;
if (!np)
return false;
prop = of_find_property(np, "pinctrl-0", &size);
return prop ? true : false;
}
int pinctrl_dt_to_map(struct pinctrl *p, struct pinctrl_dev *pctldev)
{
struct device_node *np = p->dev->of_node;
int state, ret;
char *propname;
struct property *prop;
const char *statename;
const __be32 *list;
int size, config;
phandle phandle;
struct device_node *np_config;
/* CONFIG_OF enabled, p->dev not instantiated from DT */
if (!np) {
if (of_have_populated_dt())
dev_dbg(p->dev,
"no of_node; not parsing pinctrl DT\n");
return 0;
}
/* We may store pointers to property names within the node */
of_node_get(np);
/* For each defined state ID */
for (state = 0; ; state++) {
/* Retrieve the pinctrl-* property */
propname = kasprintf(GFP_KERNEL, "pinctrl-%d", state);
prop = of_find_property(np, propname, &size);
kfree(propname);
if (!prop) {
if (state == 0) {
of_node_put(np);
return -ENODEV;
}
break;
}
list = prop->value;
size /= sizeof(*list);
/* Determine whether pinctrl-names property names the state */
ret = of_property_read_string_index(np, "pinctrl-names",
state, &statename);
/*
* If not, statename is just the integer state ID. But rather
* than dynamically allocate it and have to free it later,
* just point part way into the property name for the string.
*/
if (ret < 0) {
/* strlen("pinctrl-") == 8 */
statename = prop->name + 8;
}
/* For every referenced pin configuration node in it */
for (config = 0; config < size; config++) {
phandle = be32_to_cpup(list++);
/* Look up the pin configuration node */
np_config = of_find_node_by_phandle(phandle);
if (!np_config) {
dev_err(p->dev,
"prop %s index %i invalid phandle\n",
prop->name, config);
ret = -EINVAL;
goto err;
}
/* Parse the node */
ret = dt_to_map_one_config(p, pctldev, statename,
np_config);
of_node_put(np_config);
if (ret < 0)
goto err;
}
/* No entries in DT? Generate a dummy state table entry */
if (!size) {
ret = dt_remember_dummy_state(p, statename);
if (ret < 0)
goto err;
}
}
return 0;
err:
pinctrl_dt_free_maps(p);
return ret;
}
/*
* For pinctrl binding, typically #pinctrl-cells is for the pin controller
* device, so either parent or grandparent. See pinctrl-bindings.txt.
*/
static int pinctrl_find_cells_size(const struct device_node *np)
{
const char *cells_name = "#pinctrl-cells";
int cells_size, error;
error = of_property_read_u32(np->parent, cells_name, &cells_size);
if (error) {
error = of_property_read_u32(np->parent->parent,
cells_name, &cells_size);
if (error)
return -ENOENT;
}
return cells_size;
}
/**
* pinctrl_get_list_and_count - Gets the list and it's cell size and number
* @np: pointer to device node with the property
* @list_name: property that contains the list
* @list: pointer for the list found
* @cells_size: pointer for the cell size found
* @nr_elements: pointer for the number of elements found
*
* Typically np is a single pinctrl entry containing the list.
*/
static int pinctrl_get_list_and_count(const struct device_node *np,
const char *list_name,
const __be32 **list,
int *cells_size,
int *nr_elements)
{
int size;
*cells_size = 0;
*nr_elements = 0;
*list = of_get_property(np, list_name, &size);
if (!*list)
return -ENOENT;
*cells_size = pinctrl_find_cells_size(np);
if (*cells_size < 0)
return -ENOENT;
/* First element is always the index within the pinctrl device */
*nr_elements = (size / sizeof(**list)) / (*cells_size + 1);
return 0;
}
/**
* pinctrl_count_index_with_args - Count number of elements in a pinctrl entry
* @np: pointer to device node with the property
* @list_name: property that contains the list
*
* Counts the number of elements in a pinctrl array consisting of an index
* within the controller and a number of u32 entries specified for each
* entry. Note that device_node is always for the parent pin controller device.
*/
int pinctrl_count_index_with_args(const struct device_node *np,
const char *list_name)
{
const __be32 *list;
int size, nr_cells, error;
error = pinctrl_get_list_and_count(np, list_name, &list,
&nr_cells, &size);
if (error)
return error;
return size;
}
EXPORT_SYMBOL_GPL(pinctrl_count_index_with_args);
/**
* pinctrl_copy_args - Populates of_phandle_args based on index
* @np: pointer to device node with the property
* @list: pointer to a list with the elements
* @index: entry within the list of elements
* @nr_cells: number of cells in the list
* @nr_elem: number of elements for each entry in the list
* @out_args: returned values
*
* Populates the of_phandle_args based on the index in the list.
*/
static int pinctrl_copy_args(const struct device_node *np,
const __be32 *list,
int index, int nr_cells, int nr_elem,
struct of_phandle_args *out_args)
{
int i;
memset(out_args, 0, sizeof(*out_args));
out_args->np = (struct device_node *)np;
out_args->args_count = nr_cells + 1;
if (index >= nr_elem)
return -EINVAL;
list += index * (nr_cells + 1);
for (i = 0; i < nr_cells + 1; i++)
out_args->args[i] = be32_to_cpup(list++);
return 0;
}
/**
* pinctrl_parse_index_with_args - Find a node pointed by index in a list
* @np: pointer to device node with the property
* @list_name: property that contains the list
* @index: index within the list
* @out_arts: entries in the list pointed by index
*
* Finds the selected element in a pinctrl array consisting of an index
* within the controller and a number of u32 entries specified for each
* entry. Note that device_node is always for the parent pin controller device.
*/
int pinctrl_parse_index_with_args(const struct device_node *np,
const char *list_name, int index,
struct of_phandle_args *out_args)
{
const __be32 *list;
int nr_elem, nr_cells, error;
error = pinctrl_get_list_and_count(np, list_name, &list,
&nr_cells, &nr_elem);
if (error || !nr_cells)
return error;
error = pinctrl_copy_args(np, list, index, nr_cells, nr_elem,
out_args);
if (error)
return error;
return 0;
}
EXPORT_SYMBOL_GPL(pinctrl_parse_index_with_args);