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platform形式的驱动程序

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tao180539|  楼主 | 2022-4-30 22:02 | 只看该作者 回帖奖励 |倒序浏览 |阅读模式
本帖最后由 tao180539 于 2022-4-30 22:03 编辑

文件是从mini2440开发板资料中直接复制的, platform形式的驱动程序,在驱动中的driver部分没有filefop结构体,这个程序对吗,若是对的话,在实际应用中应用层的read, write是通过哪个函数实现的,请教一下。
/* arch/arm/plat-s3c24xx/adc.c
*
* Copyright (c) 2008 Simtec Electronics
*        http://armlinux.simtec.co.uk/
*        Ben Dooks <ben@simtec.co.uk>, <ben-linux@fluff.org>
*
* S3C24XX ADC device core
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License.
*/

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/list.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/interrupt.h>
#include <linux/io.h>

#include <plat/regs-adc.h>
#include <plat/adc.h>

/* This driver is designed to control the usage of the ADC block between
* the touchscreen and any other drivers that may need to use it, such as
* the hwmon driver.
*
* Priority will be given to the touchscreen driver, but as this itself is
* rate limited it should not starve other requests which are processed in
* order that they are received.
*
* Each user registers to get a client block which uniquely identifies it
* and stores information such as the necessary functions to callback when
* action is required.
*/

struct s3c_adc_client {
        struct platform_device        *pdev;
        struct list_head         pend;
        wait_queue_head_t        *wait;

        unsigned int                 nr_samples;
        int                         result;
        unsigned char                 is_ts;
        unsigned char                 channel;

        void        (*select_cb)(struct s3c_adc_client *c, unsigned selected);
        void        (*convert_cb)(struct s3c_adc_client *c,
                              unsigned val1, unsigned val2,
                              unsigned *samples_left);
};

struct adc_device {
        struct platform_device        *pdev;
        struct platform_device        *owner;
        struct clk                *clk;
        struct s3c_adc_client        *cur;
        struct s3c_adc_client        *ts_pend;
        void __iomem                *regs;

        unsigned int                 prescale;

        int                         irq;
};

static struct adc_device *adc_dev;

static LIST_HEAD(adc_pending);

#define adc_dbg(_adc, msg...) dev_dbg(&(_adc)->pdev->dev, msg)

static inline void s3c_adc_convert(struct adc_device *adc)
{
        unsigned con = readl(adc->regs + S3C2410_ADCCON);

        con |= S3C2410_ADCCON_ENABLE_START;
        writel(con, adc->regs + S3C2410_ADCCON);
}

static inline void s3c_adc_select(struct adc_device *adc,
                                  struct s3c_adc_client *client)
{
        unsigned con = readl(adc->regs + S3C2410_ADCCON);

        client->select_cb(client, 1);

        con &= ~S3C2410_ADCCON_MUXMASK;
        con &= ~S3C2410_ADCCON_STDBM;
        con &= ~S3C2410_ADCCON_STARTMASK;

        if (!client->is_ts)
                con |= S3C2410_ADCCON_SELMUX(client->channel);

        writel(con, adc->regs + S3C2410_ADCCON);
}

static void s3c_adc_dbgshow(struct adc_device *adc)
{
        adc_dbg(adc, "CON=%08x, TSC=%08x, DLY=%08x\n",
                readl(adc->regs + S3C2410_ADCCON),
                readl(adc->regs + S3C2410_ADCTSC),
                readl(adc->regs + S3C2410_ADCDLY));
}

static void s3c_adc_try(struct adc_device *adc)
{
        struct s3c_adc_client *next = adc->ts_pend;

        if (!next && !list_empty(&adc_pending)) {
                next = list_first_entry(&adc_pending,
                                        struct s3c_adc_client, pend);
                list_del(&next->pend);
        } else
                adc->ts_pend = NULL;

        if (next) {
                adc_dbg(adc, "new client is %p\n", next);
                adc->cur = next;
                s3c_adc_select(adc, next);
                s3c_adc_convert(adc);
                s3c_adc_dbgshow(adc);
        }
}

int s3c_adc_start(struct s3c_adc_client *client,
                  unsigned int channel, unsigned int nr_samples)
{
        struct adc_device *adc = adc_dev;
        unsigned long flags;

        if (!adc) {
                printk(KERN_ERR "%s: failed to find adc\n", __func__);
                return -EINVAL;
        }

        if (client->is_ts && adc->ts_pend)
                return -EAGAIN;

        local_irq_save(flags);

        client->channel = channel;
        client->nr_samples = nr_samples;

        if (client->is_ts)
                adc->ts_pend = client;
        else
                list_add_tail(&client->pend, &adc_pending);

        if (!adc->cur)
                s3c_adc_try(adc);
        local_irq_restore(flags);

        return 0;
}
EXPORT_SYMBOL_GPL(s3c_adc_start);

static void s3c_convert_done(struct s3c_adc_client *client,
                             unsigned v, unsigned u, unsigned *left)
{
        client->result = v;
        wake_up(client->wait);
}

int s3c_adc_read(struct s3c_adc_client *client, unsigned int ch)
{
        DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wake);
        int ret;

        client->convert_cb = s3c_convert_done;
        client->wait = &wake;
        client->result = -1;

        ret = s3c_adc_start(client, ch, 1);
        if (ret < 0)
                goto err;

        ret = wait_event_timeout(wake, client->result >= 0, HZ / 2);
        if (client->result < 0) {
                ret = -ETIMEDOUT;
                goto err;
        }

        client->convert_cb = NULL;
        return client->result;

err:
        return ret;
}
EXPORT_SYMBOL_GPL(s3c_adc_read);

static void s3c_adc_default_select(struct s3c_adc_client *client,
                                   unsigned select)
{
}

struct s3c_adc_client *s3c_adc_register(struct platform_device *pdev,
                                        void (*select)(struct s3c_adc_client *client,
                                                       unsigned int selected),
                                        void (*conv)(struct s3c_adc_client *client,
                                                     unsigned d0, unsigned d1,
                                                     unsigned *samples_left),
                                        unsigned int is_ts)
{
        struct s3c_adc_client *client;

        WARN_ON(!pdev);

        if (!select)
                select = s3c_adc_default_select;

        if (!pdev)
                return ERR_PTR(-EINVAL);

        client = kzalloc(sizeof(struct s3c_adc_client), GFP_KERNEL);
        if (!client) {
                dev_err(&pdev->dev, "no memory for adc client\n");
                return ERR_PTR(-ENOMEM);
        }

        client->pdev = pdev;
        client->is_ts = is_ts;
        client->select_cb = select;
        client->convert_cb = conv;

        return client;
}
EXPORT_SYMBOL_GPL(s3c_adc_register);

void s3c_adc_release(struct s3c_adc_client *client)
{
        /* We should really check that nothing is in progress. */
        if (adc_dev->cur == client)
                adc_dev->cur = NULL;
        if (adc_dev->ts_pend == client)
                adc_dev->ts_pend = NULL;
        else {
                struct list_head *p, *n;
                struct s3c_adc_client *tmp;

                list_for_each_safe(p, n, &adc_pending) {
                        tmp = list_entry(p, struct s3c_adc_client, pend);
                        if (tmp == client)
                                list_del(&tmp->pend);
                }
        }

        if (adc_dev->cur == NULL)
                s3c_adc_try(adc_dev);
        kfree(client);
}
EXPORT_SYMBOL_GPL(s3c_adc_release);

static irqreturn_t s3c_adc_irq(int irq, void *pw)
{
        struct adc_device *adc = pw;
        struct s3c_adc_client *client = adc->cur;
        unsigned long flags;
        unsigned data0, data1;

        if (!client) {
                dev_warn(&adc->pdev->dev, "%s: no adc pending\n", __func__);
                return IRQ_HANDLED;
        }

        data0 = readl(adc->regs + S3C2410_ADCDAT0);
        data1 = readl(adc->regs + S3C2410_ADCDAT1);
        adc_dbg(adc, "read %d: 0x%04x, 0x%04x\n", client->nr_samples, data0, data1);

        client->nr_samples--;

        if (client->convert_cb)
                (client->convert_cb)(client, data0 & 0x3ff, data1 & 0x3ff,
                                     &client->nr_samples);

        if (client->nr_samples > 0) {
                /* fire another conversion for this */

                client->select_cb(client, 1);
                s3c_adc_convert(adc);
        } else {
                local_irq_save(flags);
                (client->select_cb)(client, 0);
                adc->cur = NULL;

                s3c_adc_try(adc);
                local_irq_restore(flags);
        }

        return IRQ_HANDLED;
}

static int s3c_adc_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct adc_device *adc;
        struct resource *regs;
        int ret;

        adc = kzalloc(sizeof(struct adc_device), GFP_KERNEL);
        if (adc == NULL) {
                dev_err(dev, "failed to allocate adc_device\n");
                return -ENOMEM;
        }

        adc->pdev = pdev;
        adc->prescale = S3C2410_ADCCON_PRSCVL(49);

        adc->irq = platform_get_irq(pdev, 1);
        if (adc->irq <= 0) {
                dev_err(dev, "failed to get adc irq\n");
                ret = -ENOENT;
                goto err_alloc;
        }

        ret = request_irq(adc->irq, s3c_adc_irq, 0, dev_name(dev), adc);
        if (ret < 0) {
                dev_err(dev, "failed to attach adc irq\n");
                goto err_alloc;
        }

        adc->clk = clk_get(dev, "adc");
        if (IS_ERR(adc->clk)) {
                dev_err(dev, "failed to get adc clock\n");
                ret = PTR_ERR(adc->clk);
                goto err_irq;
        }

        regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!regs) {
                dev_err(dev, "failed to find registers\n");
                ret = -ENXIO;
                goto err_clk;
        }

        adc->regs = ioremap(regs->start, resource_size(regs));
        if (!adc->regs) {
                dev_err(dev, "failed to map registers\n");
                ret = -ENXIO;
                goto err_clk;
        }

        clk_enable(adc->clk);

        writel(adc->prescale | S3C2410_ADCCON_PRSCEN,
               adc->regs + S3C2410_ADCCON);

        dev_info(dev, "attached adc driver\n");

        platform_set_drvdata(pdev, adc);
        adc_dev = adc;

        return 0;

err_clk:
        clk_put(adc->clk);

err_irq:
        free_irq(adc->irq, adc);

err_alloc:
        kfree(adc);
        return ret;
}

static int s3c_adc_remove(struct platform_device *pdev)
{
        struct adc_device *adc = platform_get_drvdata(pdev);

        iounmap(adc->regs);
        free_irq(adc->irq, adc);
        clk_disable(adc->clk);
        clk_put(adc->clk);
        kfree(adc);

        return 0;
}

#ifdef CONFIG_PM
static int s3c_adc_suspend(struct platform_device *pdev, pm_message_t state)
{
        struct adc_device *adc = platform_get_drvdata(pdev);
        u32 con;

        con = readl(adc->regs + S3C2410_ADCCON);
        con |= S3C2410_ADCCON_STDBM;
        writel(con, adc->regs + S3C2410_ADCCON);

        clk_disable(adc->clk);

        return 0;
}

static int s3c_adc_resume(struct platform_device *pdev)
{
        struct adc_device *adc = platform_get_drvdata(pdev);

        clk_enable(adc->clk);

        writel(adc->prescale | S3C2410_ADCCON_PRSCEN,
               adc->regs + S3C2410_ADCCON);

        return 0;
}

#else
#define s3c_adc_suspend NULL
#define s3c_adc_resume NULL
#endif

static struct platform_driver s3c_adc_driver = {
        .driver                = {
                .name        = "s3c24xx-adc",
                .owner        = THIS_MODULE,
        },
        .probe                = s3c_adc_probe,
        .remove                = __devexit_p(s3c_adc_remove),
        .suspend        = s3c_adc_suspend,
        .resume                = s3c_adc_resume,
};

static int __init adc_init(void)
{
        int ret;

        ret = platform_driver_register(&s3c_adc_driver);
        if (ret)
                printk(KERN_ERR "%s: failed to add adc driver\n", __func__);

        return ret;
}

arch_initcall(adc_init);


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