root/drivers/misc/atmel-ssc.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Atmel SSC driver
 *
 * Copyright (C) 2007 Atmel Corporation
 */

#include <linux/platform_device.h>
#include <linux/list.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/mutex.h>
#include <linux/atmel-ssc.h>
#include <linux/slab.h>
#include <linux/module.h>

#include <linux/of.h>

#include "../../sound/soc/atmel/atmel_ssc_dai.h"

/* Serialize access to ssc_list and user count */
static DEFINE_MUTEX(user_lock);
static LIST_HEAD(ssc_list);

struct ssc_device *ssc_request(unsigned int ssc_num)
{
        int ssc_valid = 0;
        struct ssc_device *ssc;

        mutex_lock(&user_lock);
        list_for_each_entry(ssc, &ssc_list, list) {
                if (ssc->pdev->dev.of_node) {
                        if (of_alias_get_id(ssc->pdev->dev.of_node, "ssc")
                                == ssc_num) {
                                ssc->pdev->id = ssc_num;
                                ssc_valid = 1;
                                break;
                        }
                } else if (ssc->pdev->id == ssc_num) {
                        ssc_valid = 1;
                        break;
                }
        }

        if (!ssc_valid) {
                mutex_unlock(&user_lock);
                pr_err("ssc: ssc%d platform device is missing\n", ssc_num);
                return ERR_PTR(-ENODEV);
        }

        if (ssc->user) {
                mutex_unlock(&user_lock);
                dev_dbg(&ssc->pdev->dev, "module busy\n");
                return ERR_PTR(-EBUSY);
        }
        ssc->user++;
        mutex_unlock(&user_lock);

        clk_prepare(ssc->clk);

        return ssc;
}
EXPORT_SYMBOL(ssc_request);

void ssc_free(struct ssc_device *ssc)
{
        bool disable_clk = true;

        mutex_lock(&user_lock);
        if (ssc->user)
                ssc->user--;
        else {
                disable_clk = false;
                dev_dbg(&ssc->pdev->dev, "device already free\n");
        }
        mutex_unlock(&user_lock);

        if (disable_clk)
                clk_unprepare(ssc->clk);
}
EXPORT_SYMBOL(ssc_free);

static struct atmel_ssc_platform_data at91rm9200_config = {
        .use_dma = 0,
        .has_fslen_ext = 0,
};

static struct atmel_ssc_platform_data at91sam9rl_config = {
        .use_dma = 0,
        .has_fslen_ext = 1,
};

static struct atmel_ssc_platform_data at91sam9g45_config = {
        .use_dma = 1,
        .has_fslen_ext = 1,
};

static const struct platform_device_id atmel_ssc_devtypes[] = {
        {
                .name = "at91rm9200_ssc",
                .driver_data = (unsigned long) &at91rm9200_config,
        }, {
                .name = "at91sam9rl_ssc",
                .driver_data = (unsigned long) &at91sam9rl_config,
        }, {
                .name = "at91sam9g45_ssc",
                .driver_data = (unsigned long) &at91sam9g45_config,
        }, {
                /* sentinel */
        }
};

#ifdef CONFIG_OF
static const struct of_device_id atmel_ssc_dt_ids[] = {
        {
                .compatible = "atmel,at91rm9200-ssc",
                .data = &at91rm9200_config,
        }, {
                .compatible = "atmel,at91sam9rl-ssc",
                .data = &at91sam9rl_config,
        }, {
                .compatible = "atmel,at91sam9g45-ssc",
                .data = &at91sam9g45_config,
        }, {
                /* sentinel */
        }
};
MODULE_DEVICE_TABLE(of, atmel_ssc_dt_ids);
#endif

static inline const struct atmel_ssc_platform_data *
        atmel_ssc_get_driver_data(struct platform_device *pdev)
{
        if (pdev->dev.of_node) {
                const struct of_device_id *match;
                match = of_match_node(atmel_ssc_dt_ids, pdev->dev.of_node);
                if (match == NULL)
                        return NULL;
                return match->data;
        }

        return (struct atmel_ssc_platform_data *)
                platform_get_device_id(pdev)->driver_data;
}

#ifdef CONFIG_SND_ATMEL_SOC_SSC
static int ssc_sound_dai_probe(struct ssc_device *ssc)
{
        struct device_node *np = ssc->pdev->dev.of_node;
        int ret;
        int id;

        ssc->sound_dai = false;

        if (!of_property_present(np, "#sound-dai-cells"))
                return 0;

        id = of_alias_get_id(np, "ssc");
        if (id < 0)
                return id;

        ret = atmel_ssc_set_audio(id);
        ssc->sound_dai = !ret;

        return ret;
}

static void ssc_sound_dai_remove(struct ssc_device *ssc)
{
        if (!ssc->sound_dai)
                return;

        atmel_ssc_put_audio(of_alias_get_id(ssc->pdev->dev.of_node, "ssc"));
}
#else
static inline int ssc_sound_dai_probe(struct ssc_device *ssc)
{
        if (of_property_present(ssc->pdev->dev.of_node, "#sound-dai-cells"))
                return -ENOTSUPP;

        return 0;
}

static inline void ssc_sound_dai_remove(struct ssc_device *ssc)
{
}
#endif

static int ssc_probe(struct platform_device *pdev)
{
        struct resource *regs;
        struct ssc_device *ssc;
        const struct atmel_ssc_platform_data *plat_dat;

        ssc = devm_kzalloc(&pdev->dev, sizeof(struct ssc_device), GFP_KERNEL);
        if (!ssc) {
                dev_dbg(&pdev->dev, "out of memory\n");
                return -ENOMEM;
        }

        ssc->pdev = pdev;

        plat_dat = atmel_ssc_get_driver_data(pdev);
        if (!plat_dat)
                return -ENODEV;
        ssc->pdata = (struct atmel_ssc_platform_data *)plat_dat;

        if (pdev->dev.of_node) {
                struct device_node *np = pdev->dev.of_node;
                ssc->clk_from_rk_pin =
                        of_property_read_bool(np, "atmel,clk-from-rk-pin");
        }

        ssc->regs = devm_platform_get_and_ioremap_resource(pdev, 0, &regs);
        if (IS_ERR(ssc->regs))
                return PTR_ERR(ssc->regs);

        ssc->phybase = regs->start;

        ssc->clk = devm_clk_get(&pdev->dev, "pclk");
        if (IS_ERR(ssc->clk)) {
                dev_dbg(&pdev->dev, "no pclk clock defined\n");
                return -ENXIO;
        }

        /* disable all interrupts */
        clk_prepare_enable(ssc->clk);
        ssc_writel(ssc->regs, IDR, -1);
        ssc_readl(ssc->regs, SR);
        clk_disable_unprepare(ssc->clk);

        ssc->irq = platform_get_irq(pdev, 0);
        if (ssc->irq < 0) {
                dev_dbg(&pdev->dev, "could not get irq\n");
                return ssc->irq;
        }

        mutex_lock(&user_lock);
        list_add_tail(&ssc->list, &ssc_list);
        mutex_unlock(&user_lock);

        platform_set_drvdata(pdev, ssc);

        dev_info(&pdev->dev, "Atmel SSC device at 0x%p (irq %d)\n",
                        ssc->regs, ssc->irq);

        if (ssc_sound_dai_probe(ssc))
                dev_err(&pdev->dev, "failed to auto-setup ssc for audio\n");

        return 0;
}

static void ssc_remove(struct platform_device *pdev)
{
        struct ssc_device *ssc = platform_get_drvdata(pdev);

        ssc_sound_dai_remove(ssc);

        mutex_lock(&user_lock);
        list_del(&ssc->list);
        mutex_unlock(&user_lock);
}

static struct platform_driver ssc_driver = {
        .driver         = {
                .name           = "ssc",
                .of_match_table = of_match_ptr(atmel_ssc_dt_ids),
        },
        .id_table       = atmel_ssc_devtypes,
        .probe          = ssc_probe,
        .remove         = ssc_remove,
};
module_platform_driver(ssc_driver);

MODULE_AUTHOR("Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>");
MODULE_DESCRIPTION("SSC driver for Atmel AT91");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:ssc");