这一节我们看下探测函数tasklet中的两个函数，首先看下发现卡函数dw_mci_tasklet_card：
static void dw_mci_tasklet_card(unsigned long data)
{
struct dw_mci *host = (struct dw_mci *)data;
int i;
//每个slot都执行一次，本例只有一个
for (i = 0; i < host->num_slots; i++) {
struct dw_mci_slot *slot = host->slot[i];
struct mmc_host *mmc = slot->mmc;
struct mmc_request *mrq;
int present;
u32 ctrl;
present = dw_mci_get_cd(mmc); //获取卡状态，后面讲
while (present != slot->last_detect_state) {
spin_lock(&host->lock);
dev_dbg(&slot->mmc->class_dev, "card %s\n",
present ? "inserted" : "removed");
/* Card change detected */
slot->last_detect_state = present;
/* Power up slot */
if (present != 0) {
if (host->pdata->setpower)
host->pdata->setpower(slot->id,
mmc->ocr_avail);
set_bit(DW_MMC_CARD_PRESENT, &slot->flags); //设置卡存在标志
}
/* Clean up queue if present */
mrq = slot->mrq;
if (mrq) {
if (mrq == host->mrq) {
host->data = NULL;
host->cmd = NULL;
switch (host->state) {
case STATE_IDLE:
break;
case STATE_SENDING_CMD:
mrq->cmd->error = -ENOMEDIUM;
if (!mrq->data)
break;
/* fall through */
case STATE_SENDING_DATA:
mrq->data->error = -ENOMEDIUM;
dw_mci_stop_dma(host); //停止DMA，后面讲
break;
case STATE_DATA_BUSY:
case STATE_DATA_ERROR:
if (mrq->data->error == -EINPROGRESS)
mrq->data->error = -ENOMEDIUM;
if (!mrq->stop)
break;
/* fall through */
case STATE_SENDING_STOP:
mrq->stop->error = -ENOMEDIUM;
break;
}
dw_mci_request_end(host, mrq); //停止请求，后面讲
} else {
list_del(&slot->queue_node);
mrq->cmd->error = -ENOMEDIUM;
if (mrq->data)
mrq->data->error = -ENOMEDIUM;
if (mrq->stop)
mrq->stop->error = -ENOMEDIUM;
spin_unlock(&host->lock);
mmc_request_done(slot->mmc, mrq);
spin_lock(&host->lock);
}
}
/* Power down slot */
if (present == 0) {
if (host->pdata->setpower)
host->pdata->setpower(slot->id, 0);
clear_bit(DW_MMC_CARD_PRESENT, &slot->flags);
/*
* Clear down the FIFO - doing so generates a
* block interrupt, hence setting the
* scatter-gather pointer to NULL.
*/
host->sg = NULL;
ctrl = mci_readl(host, CTRL);
ctrl |= SDMMC_CTRL_FIFO_RESET;
mci_writel(host, CTRL, ctrl); //复位fifo
#ifdef CONFIG_MMC_DW_IDMAC
ctrl = mci_readl(host, BMOD);
ctrl |= 0x01; /* Software reset of DMA */
mci_writel(host, BMOD, ctrl);
#endif
}
spin_unlock(&host->lock);
present = dw_mci_get_cd(mmc);
}
mmc_detect_change(slot->mmc,
msecs_to_jiffies(host->pdata->detect_delay_ms));
}
}
获取卡状态：
static int dw_mci_get_cd(struct mmc_host *mmc)
{
int present;
struct dw_mci_slot *slot = mmc_priv(mmc);
struct dw_mci_board *brd = slot->host->pdata;
/* Use platform get_cd function, else try onboard card detect */
if (brd->quirks & DW_MCI_QUIRK_BROKEN_CARD_DETECTION)
present = 1;
else if (brd->get_cd)
present = !brd->get_cd(slot->id);
else
present = (mci_readl(slot->host, CDETECT) & (1 << slot->id))
== 0 ? 1 : 0; //读取寄存器获取卡状态
if (present)
dev_dbg(&mmc->class_dev, "card is present\n");
else
dev_dbg(&mmc->class_dev, "card is not present\n");
return present;
}
停止DMA：
/* DMA interface functions */
static void dw_mci_stop_dma(struct dw_mci *host)
{
//执行if，因为我们在内部DMA初始化时，已经将host->use_dma置1了
if (host->use_dma) {
host->dma_ops->stop(host);
host->dma_ops->cleanup(host);
} else {
/* Data transfer was stopped by the interrupt handler */
set_bit(EVENT_XFER_COMPLETE, &host->pending_events);
}
}
停止请求：
static void dw_mci_request_end(struct dw_mci *host, struct mmc_request *mrq)
__releases(&host->lock)
__acquires(&host->lock)
{
struct dw_mci_slot *slot;
struct mmc_host *prev_mmc = host->cur_slot->mmc;
WARN_ON(host->cmd || host->data);
host->cur_slot->mrq = NULL;
host->mrq = NULL;
if (!list_empty(&host->queue)) {
slot = list_entry(host->queue.next,
struct dw_mci_slot, queue_node);
list_del(&slot->queue_node);
dev_vdbg(&host->pdev->dev, "list not empty: %s is next\n",
mmc_hostname(slot->mmc));
host->state = STATE_SENDING_CMD;
dw_mci_start_request(host, slot); //在请求中讲述
} else {
dev_vdbg(&host->pdev->dev, "list empty\n");
host->state = STATE_IDLE;
}
spin_unlock(&host->lock);
mmc_request_done(prev_mmc, mrq);
spin_lock(&host->lock);
}
接下来讲述tasklet另外一个函数dw_mci_tasklet_func：
static void dw_mci_tasklet_func(unsigned long priv)
{
struct dw_mci *host = (struct dw_mci *)priv;
struct mmc_data *data;
struct mmc_command *cmd;
enum dw_mci_state state;
enum dw_mci_state prev_state;
u32 status;
spin_lock(&host->lock);
state = host->state;
data = host->data;
do {
prev_state = state;
//host->pending_events的值都是在中断中被置的
switch (state) {
case STATE_IDLE:
break;
case STATE_SENDING_CMD:
if (!test_and_clear_bit(EVENT_CMD_COMPLETE,
&host->pending_events))
break;
cmd = host->cmd;
host->cmd = NULL;
set_bit(EVENT_CMD_COMPLETE, &host->completed_events);
dw_mci_command_complete(host, host->mrq->cmd); //命令完成，后面讲
if (!host->mrq->data || cmd->error) {
dw_mci_request_end(host, host->mrq);
goto unlock;
}
prev_state = state = STATE_SENDING_DATA;
/* fall through */
case STATE_SENDING_DATA:
if (test_and_clear_bit(EVENT_DATA_ERROR,
&host->pending_events)) {
dw_mci_stop_dma(host);
if (data->stop)
send_stop_cmd(host, data); //发送结束命令，后面讲述
state = STATE_DATA_ERROR;
break;
}
if (!test_and_clear_bit(EVENT_XFER_COMPLETE,
&host->pending_events))
break;
set_bit(EVENT_XFER_COMPLETE, &host->completed_events);
prev_state = state = STATE_DATA_BUSY;
/* fall through */
case STATE_DATA_BUSY:
if (!test_and_clear_bit(EVENT_DATA_COMPLETE,
&host->pending_events))
break;
host->data = NULL;
set_bit(EVENT_DATA_COMPLETE, &host->completed_events);
status = host->data_status;
if (status & DW_MCI_DATA_ERROR_FLAGS) {
if (status & SDMMC_INT_DTO) {
dev_err(&host->pdev->dev,
"data timeout error\n");
data->error = -ETIMEDOUT;
} else if (status & SDMMC_INT_DCRC) {
dev_err(&host->pdev->dev,
"data CRC error\n");
data->error = -EILSEQ;
} else {
dev_err(&host->pdev->dev,
"data FIFO error "
"(status=%08x)\n",
status);
data->error = -EIO;
}
} else {
data->bytes_xfered = data->blocks * data->blksz;
data->error = 0;
}
if (!data->stop) {
dw_mci_request_end(host, host->mrq);
goto unlock;
}
prev_state = state = STATE_SENDING_STOP;
if (!data->error)
send_stop_cmd(host, data);
/* fall through */
case STATE_SENDING_STOP:
if (!test_and_clear_bit(EVENT_CMD_COMPLETE,
&host->pending_events))
break;
host->cmd = NULL;
dw_mci_command_complete(host, host->mrq->stop);
dw_mci_request_end(host, host->mrq);
goto unlock;
case STATE_DATA_ERROR:
if (!test_and_clear_bit(EVENT_XFER_COMPLETE,
&host->pending_events))
break;
state = STATE_DATA_BUSY;
break;
}
} while (state != prev_state);
host->state = state;
unlock:
spin_unlock(&host->lock);
}
命令完成：
static void dw_mci_command_complete(struct dw_mci *host, struct mmc_command *cmd)
{
u32 status = host->cmd_status;
host->cmd_status = 0;
/* Read the response from the card (up to 16 bytes) */
if (cmd->flags & MMC_RSP_PRESENT) {
if (cmd->flags & MMC_RSP_136) {
cmd->resp[3] = mci_readl(host, RESP0);
cmd->resp[2] = mci_readl(host, RESP1);
cmd->resp[1] = mci_readl(host, RESP2);
cmd->resp[0] = mci_readl(host, RESP3);
} else {
cmd->resp[0] = mci_readl(host, RESP0);
cmd->resp[1] = 0;
cmd->resp[2] = 0;
cmd->resp[3] = 0;
}
}
if (status & SDMMC_INT_RTO)
cmd->error = -ETIMEDOUT;
else if ((cmd->flags & MMC_RSP_CRC) && (status & SDMMC_INT_RCRC))
cmd->error = -EILSEQ;
else if (status & SDMMC_INT_RESP_ERR)
cmd->error = -EIO;
else
cmd->error = 0;
if (cmd->error) {
/* newer ip versions need a delay between retries */
if (host->quirks & DW_MCI_QUIRK_RETRY_DELAY)
mdelay(20);
if (cmd->data) {
host->data = NULL;
dw_mci_stop_dma(host);
}
}
}
发送结束命令：
static void send_stop_cmd(struct dw_mci *host, struct mmc_data *data)
{
dw_mci_start_command(host, data->stop, host->stop_cmdr);
}
static void dw_mci_start_command(struct dw_mci *host,
struct mmc_command *cmd, u32 cmd_flags)
{
host->cmd = cmd;
dev_vdbg(&host->pdev->dev,
"start command: ARGR=0x%08x CMDR=0x%08x\n",
cmd->arg, cmd_flags);
mci_writel(host, CMDARG, cmd->arg);
wmb();
if (cmd->opcode == SD_APP_SEND_SCR)
mci_writel(host, CMD, cmd_flags | SDMMC_CMD_START | SDMMC_CMD_SEND_STOP);
else
mci_writel(host, CMD, cmd_flags | SDMMC_CMD_START);
}
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