linux mmc时钟频率

#include <linux/module.h>
#include <linux/mmc/core.h>
#include <linux/mmc/card.h>

static int mmc_set_clock_freq(struct mmc_card *card, unsigned int freq)
{
    struct mmc_host *host = card->host;
    int ret;

    ret = mmc_host_set_clk_rate(host, freq);
    if (ret)
        printk(KERN_ERR "Failed to set MMC clock frequency: %d\n", ret);

    return ret;
}

static int __init mmc_clock_init(void)
{
    struct mmc_card *card;
    unsigned int new_freq = 50000000; // 50 MHz

    card = mmc_alloc_card(mmc_get_host(0), NULL);
    if (!card)
        return -ENOMEM;

    mmc_set_clock_freq(card, new_freq);

    mmc_release_card(card);
    return 0;
}

static void __exit mmc_clock_exit(void)
{
    printk(KERN_INFO "MMC clock module unloaded.\n");
}

module_init(mmc_clock_init);
module_exit(mmc_clock_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Module to adjust MMC clock frequency");