c - 我应该在平台设备上的什么地方存储动态分配的内存(不使用全局变量)？

Question

我想让我正在编写的平台驱动程序可重入:我在哪里存储在探测和/或打开调用期间动态分配的内存 (int probe(struct platform_device*)/ int open(struct inode *inode, struct file *))

驱动程序可以在多个系统内硬件上实例化，每个硬件都可以从用户空间同时访问。

我可以使用 struct file 中的 private_data 字段吗？和来自 struct device 的 platform_data作为指向已分配内存的任意指针？

Answer 1

如果您正在编写平台驱动程序，则应使用dev_set_drvdata() 函数，which sets the driver_data field in struct device , .

有一个例子。

struct blink_local {
    int irq;
    unsigned long mem_start;
    unsigned long mem_end;
    void __iomem *base_addr;
};

static int blink_probe(struct platform_device *pdev)
{
    struct resource *r_irq; /* Interrupt resources */
    struct resource *r_mem; /* IO mem resources */
    struct device *dev = &pdev->dev;
    struct blink_local *lp = NULL;

    int rc = 0;
    dev_info(dev, "Device Tree Probing\n");
    /* Get iospace for the device */
    r_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (!r_mem) {
        dev_err(dev, "invalid address\n");
        return -ENODEV;
    }

    lp = (struct blink_local *) kmalloc(sizeof(struct blink_local), GFP_KERNEL);
    if (!lp) {
        dev_err(dev, "Cound not allocate blink device\n");
        return -ENOMEM;
    }

    dev_set_drvdata(dev, lp);
    lp->mem_start = r_mem->start;
    lp->mem_end = r_mem->end;

    if (!request_mem_region(lp->mem_start,
                lp->mem_end - lp->mem_start + 1,
                DRIVER_NAME)) {
        dev_err(dev, "Couldn't lock memory region at %p\n",
            (void *)lp->mem_start);
        rc = -EBUSY;
        goto error1;
    }

    lp->base_addr = ioremap(lp->mem_start, lp->mem_end - lp->mem_start + 1);
    if (!lp->base_addr) {
        dev_err(dev, "blink: Could not allocate iomem\n");
        rc = -EIO;
        goto error2;
    }

    /* Get IRQ for the device */
    r_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
    if (!r_irq) {
        dev_info(dev, "no IRQ found\n");
        dev_info(dev, "blink at 0x%08x mapped to 0x%08x\n",
            (unsigned int __force)lp->mem_start,
            (unsigned int __force)lp->base_addr);
        return 0;
    }
    lp->irq = r_irq->start;
    rc = request_irq(lp->irq, &blink_irq, 0, DRIVER_NAME, lp);
    if (rc) {
        dev_err(dev, "testmodule: Could not allocate interrupt %d.\n",
            lp->irq);
        goto error3;
    }

    return 0;
error3:
    free_irq(lp->irq, lp);
error2:
    release_mem_region(lp->mem_start, lp->mem_end - lp->mem_start + 1);
error1:
    kfree(lp);
    dev_set_drvdata(dev, NULL);
    return rc;
}