devicetree.c

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/*
 * Device tree integration for the pin control subsystem
 *
 * Copyright (C) 2012 NVIDIA CORPORATION. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#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 {
    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) {
        struct pinctrl_ops *ops = pctldev->desc->pctlops;
        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) {
        dev_err(p->dev, "failed to alloc struct pinctrl_dt_map\n");
        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, true);
}

static struct pinctrl_dev *find_pinctrl_by_of_node(struct device_node *np)
{
    struct pinctrl_dev *pctldev;

    list_for_each_entry(pctldev, &pinctrldev_list, node)
        if (pctldev->dev->of_node == np)
            return pctldev;

    return NULL;
}

static int dt_to_map_one_config(struct pinctrl *p, const char *statename,
                struct device_node *np_config)
{
    struct device_node *np_pctldev;
    struct pinctrl_dev *pctldev;
    struct pinctrl_ops *ops;
    int ret;
    struct pinctrl_map *map;
    unsigned num_maps;

    /* Find the pin controller containing np_config */
    np_pctldev = of_node_get(np_config);
    for (;;) {
        np_pctldev = of_get_next_parent(np_pctldev);
        if (!np_pctldev || of_node_is_root(np_pctldev)) {
            dev_info(p->dev, "could not find pctldev for node %s, deferring probe\n",
                np_config->full_name);
            of_node_put(np_pctldev);
            /* OK let's just assume this will appear later then */
            return -EPROBE_DEFER;
        }
        pctldev = find_pinctrl_by_of_node(np_pctldev);
        if (pctldev)
            break;
    }
    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) {
        dev_err(p->dev, "failed to alloc struct pinctrl_map\n");
        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);
}

int pinctrl_dt_to_map(struct pinctrl *p)
{
    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) {
        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)
            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, 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;
}