SDIO驱动学习

在分析了sdio，emmc驱动后，把剩余的sdio部分也学习下。

代码很多不仔细看了，看关键的

int mmc_attach_sdio(struct mmc_host *host)
{
	
	err = mmc_send_io_op_cond(host, 0, &ocr);
	mmc_attach_bus(host, &mmc_sdio_ops);
	rocr = mmc_select_voltage(host, ocr);

	
	err = mmc_sdio_init_card(host, rocr, NULL, 0);
	
	funcs = (ocr & 0x70000000) >> 28;
	card->sdio_funcs = 0;
	for (i = 0; i < funcs; i++, card->sdio_funcs++) {
		err = sdio_init_func(host->card, i + 1);
	}

	mmc_release_host(host);
	for (i = 0;i < funcs;i++) {
		err = sdio_add_func(host->card->sdio_func[i]);
	}

	
	mmc_claim_host(host);
}

最终在/sys/bus/sdio/devices/下生成对于的设备

看下mmc_send_io_op_cond函数

#define SD_IO_SEND_OP_COND          5 /* bcr  [23:0] OCR         R4  */
int mmc_send_io_op_cond(struct mmc_host *host, u32 ocr, u32 *rocr)
{
	struct mmc_command cmd = {};
	int i, err = 0;

	cmd.opcode = SD_IO_SEND_OP_COND;
	cmd.arg = ocr;
	cmd.flags = MMC_RSP_SPI_R4 | MMC_RSP_R4 | MMC_CMD_BCR;

	for (i = 100; i; i--) {
		err = mmc_wait_for_cmd(host, &cmd, MMC_CMD_RETRIES);
			if (cmd.resp[0] & MMC_CARD_BUSY)
				break;
	}

	*rocr = cmd.resp[mmc_host_is_spi(host) ? 1 : 0];
}

发送CMD5命令，接收R4返回的状态。 

 SDIO协议文档位置https://www.sdcard.org/downloads/pls/index.html，下载这一篇SDIO Simplified Specification

 

看下sdio总线设备和驱动的匹配

static struct bus_type sdio_bus_type = {
	.match		= sdio_bus_match,
};

static int sdio_bus_match(struct device *dev, struct device_driver *drv)
{
	struct sdio_func *func = dev_to_sdio_func(dev);
	struct sdio_driver *sdrv = to_sdio_driver(drv);

	if (sdio_match_device(func, sdrv))
		return 1;

	return 0;
}

static const struct sdio_device_id *sdio_match_device(struct sdio_func *func,
	struct sdio_driver *sdrv)
{
	const struct sdio_device_id *ids;

	ids = sdrv->id_table;

	if (ids) {
		while (ids->class || ids->vendor || ids->device) {
			if (sdio_match_one(func, ids))
				return ids;
			ids++;
		}
	}

	return NULL;
}

static const struct sdio_device_id *sdio_match_one(struct sdio_func *func,
	const struct sdio_device_id *id)
{
	if (id->class != (__u8)SDIO_ANY_ID && id->class != func->class)
		return NULL;
	if (id->vendor != (__u16)SDIO_ANY_ID && id->vendor != func->vendor)
		return NULL;
	if (id->device != (__u16)SDIO_ANY_ID && id->device != func->device)
		return NULL;
	return id;
}

也就是根据sdio的id跟驱动的id进行匹配，匹配后跑probe函数。

所以我们看sdio驱动时，有类似的注册方法

static const struct sdio_device_id b43_sdio_ids[] = {
	{ SDIO_DEVICE(0x02d0, 0x044b) }, /* Nintendo Wii WLAN daughter card */
	{ SDIO_DEVICE(0x0092, 0x0004) }, /* C-guys, Inc. EW-CG1102GC */
	{ },
};

static struct sdio_driver b43_sdio_driver = {
	.name		= "b43-sdio",
	.id_table	= b43_sdio_ids,
	.probe		= b43_sdio_probe,
	.remove		= b43_sdio_remove,
};

int b43_sdio_init(void)
{
	return sdio_register_driver(&b43_sdio_driver);
}

void b43_sdio_exit(void)
{
	sdio_unregister_driver(&b43_sdio_driver);
}