i2c-mux-pinctrl.c

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/*
 * I2C multiplexer using pinctrl API
 *
 * 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/i2c.h>
#include <linux/i2c-mux.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/of_i2c.h>
#include <linux/pinctrl/consumer.h>
#include <linux/i2c-mux-pinctrl.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

struct i2c_mux_pinctrl {
    struct device *dev;
    struct i2c_mux_pinctrl_platform_data *pdata;
    struct pinctrl *pinctrl;
    struct pinctrl_state **states;
    struct pinctrl_state *state_idle;
    struct i2c_adapter *parent;
    struct i2c_adapter **busses;
};

static int i2c_mux_pinctrl_select(struct i2c_adapter *adap, void *data,
                  u32 chan)
{
    struct i2c_mux_pinctrl *mux = data;

    return pinctrl_select_state(mux->pinctrl, mux->states[chan]);
}

static int i2c_mux_pinctrl_deselect(struct i2c_adapter *adap, void *data,
                    u32 chan)
{
    struct i2c_mux_pinctrl *mux = data;

    return pinctrl_select_state(mux->pinctrl, mux->state_idle);
}

#ifdef CONFIG_OF
static int i2c_mux_pinctrl_parse_dt(struct i2c_mux_pinctrl *mux,
                struct platform_device *pdev)
{
    struct device_node *np = pdev->dev.of_node;
    int num_names, i, ret;
    struct device_node *adapter_np;
    struct i2c_adapter *adapter;

    if (!np)
        return 0;

    mux->pdata = devm_kzalloc(&pdev->dev, sizeof(*mux->pdata), GFP_KERNEL);
    if (!mux->pdata) {
        dev_err(mux->dev,
            "Cannot allocate i2c_mux_pinctrl_platform_data\n");
        return -ENOMEM;
    }

    num_names = of_property_count_strings(np, "pinctrl-names");
    if (num_names < 0) {
        dev_err(mux->dev, "Cannot parse pinctrl-names: %d\n",
            num_names);
        return num_names;
    }

    mux->pdata->pinctrl_states = devm_kzalloc(&pdev->dev,
        sizeof(*mux->pdata->pinctrl_states) * num_names,
        GFP_KERNEL);
    if (!mux->pdata->pinctrl_states) {
        dev_err(mux->dev, "Cannot allocate pinctrl_states\n");
        return -ENOMEM;
    }

    for (i = 0; i < num_names; i++) {
        ret = of_property_read_string_index(np, "pinctrl-names", i,
            &mux->pdata->pinctrl_states[mux->pdata->bus_count]);
        if (ret < 0) {
            dev_err(mux->dev, "Cannot parse pinctrl-names: %d\n",
                ret);
            return ret;
        }
        if (!strcmp(mux->pdata->pinctrl_states[mux->pdata->bus_count],
                "idle")) {
            if (i != num_names - 1) {
                dev_err(mux->dev, "idle state must be last\n");
                return -EINVAL;
            }
            mux->pdata->pinctrl_state_idle = "idle";
        } else {
            mux->pdata->bus_count++;
        }
    }

    adapter_np = of_parse_phandle(np, "i2c-parent", 0);
    if (!adapter_np) {
        dev_err(mux->dev, "Cannot parse i2c-parent\n");
        return -ENODEV;
    }
    adapter = of_find_i2c_adapter_by_node(adapter_np);
    if (!adapter) {
        dev_err(mux->dev, "Cannot find parent bus\n");
        return -ENODEV;
    }
    mux->pdata->parent_bus_num = i2c_adapter_id(adapter);
    put_device(&adapter->dev);

    return 0;
}
#else
static inline int i2c_mux_pinctrl_parse_dt(struct i2c_mux_pinctrl *mux,
                       struct platform_device *pdev)
{
    return 0;
}
#endif

static int __devinit i2c_mux_pinctrl_probe(struct platform_device *pdev)
{
    struct i2c_mux_pinctrl *mux;
    int (*deselect)(struct i2c_adapter *, void *, u32);
    int i, ret;

    mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
    if (!mux) {
        dev_err(&pdev->dev, "Cannot allocate i2c_mux_pinctrl\n");
        ret = -ENOMEM;
        goto err;
    }
    platform_set_drvdata(pdev, mux);

    mux->dev = &pdev->dev;

    mux->pdata = pdev->dev.platform_data;
    if (!mux->pdata) {
        ret = i2c_mux_pinctrl_parse_dt(mux, pdev);
        if (ret < 0)
            goto err;
    }
    if (!mux->pdata) {
        dev_err(&pdev->dev, "Missing platform data\n");
        ret = -ENODEV;
        goto err;
    }

    mux->states = devm_kzalloc(&pdev->dev,
                   sizeof(*mux->states) * mux->pdata->bus_count,
                   GFP_KERNEL);
    if (!mux->states) {
        dev_err(&pdev->dev, "Cannot allocate states\n");
        ret = -ENOMEM;
        goto err;
    }

    mux->busses = devm_kzalloc(&pdev->dev,
                   sizeof(mux->busses) * mux->pdata->bus_count,
                   GFP_KERNEL);
    if (!mux->busses) {
        dev_err(&pdev->dev, "Cannot allocate busses\n");
        ret = -ENOMEM;
        goto err;
    }

    mux->pinctrl = devm_pinctrl_get(&pdev->dev);
    if (IS_ERR(mux->pinctrl)) {
        ret = PTR_ERR(mux->pinctrl);
        dev_err(&pdev->dev, "Cannot get pinctrl: %d\n", ret);
        goto err;
    }
    for (i = 0; i < mux->pdata->bus_count; i++) {
        mux->states[i] = pinctrl_lookup_state(mux->pinctrl,
                        mux->pdata->pinctrl_states[i]);
            if (IS_ERR(mux->states[i])) {
                ret = PTR_ERR(mux->states[i]);
                dev_err(&pdev->dev,
                    "Cannot look up pinctrl state %s: %d\n",
                    mux->pdata->pinctrl_states[i], ret);
                goto err;
            }
    }
    if (mux->pdata->pinctrl_state_idle) {
        mux->state_idle = pinctrl_lookup_state(mux->pinctrl,
                        mux->pdata->pinctrl_state_idle);
        if (IS_ERR(mux->state_idle)) {
            ret = PTR_ERR(mux->state_idle);
            dev_err(&pdev->dev,
                "Cannot look up pinctrl state %s: %d\n",
                mux->pdata->pinctrl_state_idle, ret);
            goto err;
        }

        deselect = i2c_mux_pinctrl_deselect;
    } else {
        deselect = NULL;
    }

    mux->parent = i2c_get_adapter(mux->pdata->parent_bus_num);
    if (!mux->parent) {
        dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
            mux->pdata->parent_bus_num);
        ret = -ENODEV;
        goto err;
    }

    for (i = 0; i < mux->pdata->bus_count; i++) {
        u32 bus = mux->pdata->base_bus_num ?
                (mux->pdata->base_bus_num + i) : 0;

        mux->busses[i] = i2c_add_mux_adapter(mux->parent, &pdev->dev,
                             mux, bus, i, 0,
                             i2c_mux_pinctrl_select,
                             deselect);
        if (!mux->busses[i]) {
            ret = -ENODEV;
            dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
            goto err_del_adapter;
        }
    }

    return 0;

err_del_adapter:
    for (; i > 0; i--)
        i2c_del_mux_adapter(mux->busses[i - 1]);
    i2c_put_adapter(mux->parent);
err:
    return ret;
}

static int __devexit i2c_mux_pinctrl_remove(struct platform_device *pdev)
{
    struct i2c_mux_pinctrl *mux = platform_get_drvdata(pdev);
    int i;

    for (i = 0; i < mux->pdata->bus_count; i++)
        i2c_del_mux_adapter(mux->busses[i]);

    i2c_put_adapter(mux->parent);

    return 0;
}

#ifdef CONFIG_OF
static const struct of_device_id i2c_mux_pinctrl_of_match[] __devinitconst = {
    { .compatible = "i2c-mux-pinctrl", },
    {},
};
MODULE_DEVICE_TABLE(of, i2c_mux_pinctrl_of_match);
#endif

static struct platform_driver i2c_mux_pinctrl_driver = {
    .driver = {
        .name   = "i2c-mux-pinctrl",
        .owner  = THIS_MODULE,
        .of_match_table = of_match_ptr(i2c_mux_pinctrl_of_match),
    },
    .probe  = i2c_mux_pinctrl_probe,
    .remove = __devexit_p(i2c_mux_pinctrl_remove),
};
module_platform_driver(i2c_mux_pinctrl_driver);

MODULE_DESCRIPTION("pinctrl-based I2C multiplexer driver");
MODULE_AUTHOR("Stephen Warren <[email protected]>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:i2c-mux-pinctrl");