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继续上一篇文章（见 http://www.linuxidc.com/Linux/2012-02/52948.htm ），先看一个重点结构，平台相关，真正对host的设置都会回调到这里
static struct mmc_host_ops s3cmci_ops = {
.request = s3cmci_request, //用于命令和数据的发送接收
.set_ios = s3cmci_set_ios, //用于设置io
.get_ro = s3cmci_get_ro, //用于判断写保护
.get_cd = s3cmci_card_present, //判断卡是否存在
.enable_sdio_irq = s3cmci_enable_sdio_irq,
};
####先看最复杂的命令请求
static void s3cmci_request(struct mmc_host *mmc, struct mmc_request *mrq)
{
struct s3cmci_host *host = mmc_priv(mmc);
host->status = “mmc request”; //设置状态
host->cmd_is_stop = 0;
host->mrq = mrq; //请求结构描述
if (s3cmci_card_present(mmc) == 0) { //卡是否存在
dbg(host, dbg_err, “%s: no medium present\n”, __func__);
host->mrq->cmd->error = -ENOMEDIUM;
mmc_request_done(mmc, mrq); //无卡结束
} else
s3cmci_send_request(mmc); //有卡发送
}
@继续
static void s3cmci_send_request(struct mmc_host *mmc)
{
struct s3cmci_host *host = mmc_priv(mmc);
struct mmc_request *mrq = host->mrq;
struct mmc_command *cmd = host->cmd_is_stop ? mrq->stop : mrq->cmd;
//只有stop和命令请求？
host->ccnt++;
prepare_dbgmsg(host, cmd, host->cmd_is_stop);
/* Clear command, data and fifo status registers
Fifo clear only necessary on 2440, but doesn’t hurt on 2410
请求状态
*/
writel(0xFFFFFFFF, host->base + S3C2410_SDICMDSTAT);
writel(0xFFFFFFFF, host->base + S3C2410_SDIDSTA);
writel(0xFFFFFFFF, host->base + S3C2410_SDIFSTA);
if (cmd->data) {
int res = s3cmci_setup_data(host, cmd->data);
host->dcnt++;
if (res) {
dbg(host, dbg_err, “setup data error %d\n”, res);
cmd->error = res;
cmd->data->error = res;
mmc_request_done(mmc, mrq);
return;
}
if (s3cmci_host_usedma(host)) //是否用dma
res = s3cmci_prepare_dma(host, cmd->data);
else
res = s3cmci_prepare_pio(host, cmd->data);
if (res) {
dbg(host, dbg_err, “data prepare error %d\n”, res);
cmd->error = res;
cmd->data->error = res;
mmc_request_done(mmc, mrq);
return;
}
}
/* Send command */
s3cmci_send_command(host, cmd); //发送命令
/* Enable Interrupt */
s3cmci_enable_irq(host, true); //使能中断
}
###设置命令数据到相应寄存器
static int s3cmci_setup_data(struct s3cmci_host *host, struct mmc_data *data)
{
u32 dcon, imsk, stoptries = 3;
/* write DCON register */
if (!data) {
writel(0, host->base + S3C2410_SDIDCON);
return 0;
}
if ((data->blksz & 3) != 0) {
/* We cannot deal with unaligned blocks with more than
* one block being transferred. */
if (data->blocks > 1) {
pr_warning(“%s: can’t do non-word sized block transfers (blksz %d)\n”, __func__, data->blksz);
return -EINVAL;
}
}
while (readl(host->base + S3C2410_SDIDSTA) &
(S3C2410_SDIDSTA_TXDATAON | S3C2410_SDIDSTA_RXDATAON)) {
dbg(host, dbg_err,
“mci_setup_data() transfer stillin progress.\n”);
writel(S3C2410_SDIDCON_STOP, host->base + S3C2410_SDIDCON);
s3cmci_reset(host);
if ((stoptries–) == 0) {
dbg_dumpregs(host, “DRF”);
return -EINVAL;
}
}
dcon = data->blocks & S3C2410_SDIDCON_BLKNUM_MASK;
if (s3cmci_host_usedma(host))
dcon |= S3C2410_SDIDCON_DMAEN;
if (host->bus_width == MMC_BUS_WIDTH_4)
dcon |= S3C2410_SDIDCON_WIDEBUS;
if (!(data->flags & MMC_DATA_STREAM))
dcon |= S3C2410_SDIDCON_BLOCKMODE;
if (data->flags & MMC_DATA_WRITE) {
dcon |= S3C2410_SDIDCON_TXAFTERRESP;
dcon |= S3C2410_SDIDCON_XFER_TXSTART;
}
if (data->flags & MMC_DATA_READ) {
dcon |= S3C2410_SDIDCON_RXAFTERCMD;
dcon |= S3C2410_SDIDCON_XFER_RXSTART;
}
if (host->is2440) {
dcon |= S3C2440_SDIDCON_DS_WORD;
dcon |= S3C2440_SDIDCON_DATSTART;
}
writel(dcon, host->base + S3C2410_SDIDCON);
/* write BSIZE register */
writel(data->blksz, host->base + S3C2410_SDIBSIZE);
/* add to IMASK register */
imsk = S3C2410_SDIIMSK_FIFOFAIL | S3C2410_SDIIMSK_DATACRC |
S3C2410_SDIIMSK_DATATIMEOUT | S3C2410_SDIIMSK_DATAFINISH;
enable_imask(host, imsk);
/* write TIMER register */
if (host->is2440) {
writel(0x007FFFFF, host->base + S3C2410_SDITIMER);
} else {
writel(0x0000FFFF, host->base + S3C2410_SDITIMER);
/* FIX: set slow clock to prevent timeouts on read */
if (data->flags & MMC_DATA_READ)
writel(0xFF, host->base + S3C2410_SDIPRE);
}
return 0;
}####发送命令
static void s3cmci_send_command(struct s3cmci_host *host,
struct mmc_command *cmd)
{
u32 ccon, imsk;
imsk = S3C2410_SDIIMSK_CRCSTATUS | S3C2410_SDIIMSK_CMDTIMEOUT |
S3C2410_SDIIMSK_RESPONSEND | S3C2410_SDIIMSK_CMDSENT |
S3C2410_SDIIMSK_RESPONSECRC;
enable_imask(host, imsk);
if (cmd->data) //完成标志
host->complete_what = COMPLETION_XFERFINISH_RSPFIN;
else if (cmd->flags & MMC_RSP_PRESENT)
host->complete_what = COMPLETION_RSPFIN;
else
host->complete_what = COMPLETION_CMDSENT;
writel(cmd->arg, host->base + S3C2410_SDICMDARG);
ccon = cmd->opcode & S3C2410_SDICMDCON_INDEX;
ccon |= S3C2410_SDICMDCON_SENDERHOST | S3C2410_SDICMDCON_CMDSTART;
if (cmd->flags & MMC_RSP_PRESENT)
ccon |= S3C2410_SDICMDCON_WAITRSP;
if (cmd->flags & MMC_RSP_136)
ccon |= S3C2410_SDICMDCON_LONGRSP;
writel(ccon, host->base + S3C2410_SDICMDCON);
}
####使能中断，对接上前一篇文章的irq申请部分，
/**
* s3cmci_enable_irq – enable IRQ, after having disabled it.
* @host: The device state.
* @more: True if more IRQs are expected from transfer.
*
* Enable the main IRQ if needed after it has been disabled.
*
* The IRQ can be one of the following states:
* – disabled during IDLE
* – disabled whilst processing data
* – enabled during transfer
* – enabled whilst awaiting SDIO interrupt detection
*/
static void s3cmci_enable_irq(struct s3cmci_host *host, bool more)
{
unsigned long flags;
bool enable = false;
local_irq_save(flags);
host->irq_enabled = more;
host->irq_disabled = false;
enable = more | host->sdio_irqen;
if (host->irq_state != enable) {
host->irq_state = enable;
if (enable)
enable_irq(host->irq);
else
disable_irq(host->irq);
}
local_irq_restore(flags);
}
#####set_ios函数，
static void s3cmci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
{
struct s3cmci_host *host = mmc_priv(mmc);
u32 mci_con;
/* Set the power state */
mci_con = readl(host->base + S3C2410_SDICON);
switch (ios->power_mode) { //设置模式选择
case MMC_POWER_ON:
case MMC_POWER_UP: //打开或者增强都对应于配置gpio
s3c2410_gpio_cfgpin(S3C2410_GPE(5), S3C2410_GPE5_SDCLK);
s3c2410_gpio_cfgpin(S3C2410_GPE(6), S3C2410_GPE6_SDCMD);
s3c2410_gpio_cfgpin(S3C2410_GPE(7), S3C2410_GPE7_SDDAT0);
s3c2410_gpio_cfgpin(S3C2410_GPE(8), S3C2410_GPE8_SDDAT1);
s3c2410_gpio_cfgpin(S3C2410_GPE(9), S3C2410_GPE9_SDDAT2);
s3c2410_gpio_cfgpin(S3C2410_GPE(10), S3C2410_GPE10_SDDAT3);
if (host->pdata->set_power) //2440比较简单，没有verg对应设置
host->pdata->set_power(ios->power_mode, ios->vdd);
if (!host->is2440)
mci_con |= S3C2410_SDICON_FIFORESET;
break;
case MMC_POWER_OFF: //关闭部分
default:
gpio_direction_output(S3C2410_GPE(5), 0);
if (host->is2440)
mci_con |= S3C2440_SDICON_SDRESET;
if (host->pdata->set_power)
host->pdata->set_power(ios->power_mode, ios->vdd);
break;
}
s3cmci_set_clk(host, ios); //设置clk
/* Set CLOCK_ENABLE */
if (ios->clock)
mci_con |= S3C2410_SDICON_CLOCKTYPE;
else
mci_con &= ~S3C2410_SDICON_CLOCKTYPE;
writel(mci_con, host->base + S3C2410_SDICON);
if ((ios->power_mode == MMC_POWER_ON) ||
(ios->power_mode == MMC_POWER_UP)) {
dbg(host, dbg_conf, “running at %lukHz (requested: %ukHz).\n”,
host->real_rate/1000, ios->clock/1000);
} else {
dbg(host, dbg_conf, “powered down.\n”);
}
host->bus_width = ios->bus_width;
}
####设置clock函数
{
u32 mci_psc;
/* Set clock */
for (mci_psc = 0; mci_psc < 255; mci_psc++) {
host->real_rate = host->clk_rate / (host->clk_div*(mci_psc+1));
if (host->real_rate <= ios->clock)
break;
}
if (mci_psc > 255)
mci_psc = 255;
host->prescaler = mci_psc;
writel(host->prescaler, host->base + S3C2410_SDIPRE);
/* If requested clock is 0, real_rate will be 0, too */
if (ios->clock == 0)
host->real_rate = 0;
}
######写保护函数：
{
struct s3cmci_host *host = mmc_priv(mmc);
struct s3c24xx_mci_pdata *pdata = host->pdata;
int ret;
if (pdata->no_wprotect)
return 0;
ret = gpio_get_value(pdata->gpio_wprotect) ? 1 : 0;
ret ^= pdata->wprotect_invert;
return ret;
}
######探测卡函数
{
struct s3cmci_host *host = mmc_priv(mmc);
struct s3c24xx_mci_pdata *pdata = host->pdata;
int ret;
if (pdata->no_detect) //没有探测函数
return -ENOSYS;
ret = gpio_get_value(pdata->gpio_detect) ? 0 : 1; //直接读取gpio值
return ret ^ pdata->detect_invert;
}
#####下面说一下上文遗留几个函数，
void mmc_start_host(struct mmc_host *host)
{
mmc_power_off(host); //host power off
mmc_detect_change(host, 0); //detect
}
#####首先是mmc_power_off(host),
#####同文件下的
{
mmc_host_clk_hold(host); //clk可能恢复到先前的一个值，
host->ios.clock = 0; //强制设置成0？
host->ios.vdd = 0;
mmc_poweroff_notify(host);
/*
* Reset ocr mask to be the highest possible voltage supported for
* this mmc host. This value will be used at next power up.
*/
host->ocr = 1 << (fls(host->ocr_avail) – 1); //支持的最大电压
if (!mmc_host_is_spi(host)) { //不是spi
host->ios.bus_mode = MMC_BUSMODE_OPENDRAIN; //漏极开路式
host->ios.chip_select = MMC_CS_DONTCARE; //不关心cs
}
host->ios.power_mode = MMC_POWER_OFF; //状态power_off
host->ios.bus_width = MMC_BUS_WIDTH_1;
host->ios.timing = MMC_TIMING_LEGACY;
mmc_set_ios(host); //关闭电压，真正设置成0
/*
* Some configurations, such as the 802.11 SDIO card in the OLPC
* XO-1.5, require a short delay after poweroff before the card
* can be successfully turned on again.
*/
mmc_delay(1); //短暂延迟
mmc_host_clk_release(host); //disable
}
######同文件夹下
* mmc_host_clk_hold – ungate hardware MCI clocks
* @host: host to ungate.
* //gate用于限制保证有最低clk？？？
* Makes sure the host ios.clock is restored to a non-zero value
* past this call. Increase clock reference count and ungate clock
* if we’re the first user.
*/
void mmc_host_clk_hold(struct mmc_host *host)
{
unsigned long flags;
mutex_lock(&host->clk_gate_mutex);
spin_lock_irqsave(&host->clk_lock, flags);
if (host->clk_gated) {
spin_unlock_irqrestore(&host->clk_lock, flags);
mmc_ungate_clock(host);
spin_lock_irqsave(&host->clk_lock, flags);
pr_debug(“%s: ungated MCI clock\n”, mmc_hostname(host));
}
host->clk_requests++;
spin_unlock_irqrestore(&host->clk_lock, flags);
mutex_unlock(&host->clk_gate_mutex);
}
########位于drivers/mmc/core/core.c
* This restores the clock from gating by using the cached
* clock value.
*/
void mmc_ungate_clock(struct mmc_host *host)
{
/*
* We should previously have gated the clock, so the clock shall
* be 0 here! The clock may however be 0 during initialization,
* when some request operations are performed before setting
* the frequency. When ungate is requested in that situation
* we just ignore the call.
*/
if (host->clk_old) {
BUG_ON(host->ios.clock);
/* This call will also set host->clk_gated to false */
__mmc_set_clock(host, host->clk_old);
}
}
#####跟进去
* Sets the host clock to the highest possible frequency that
* is below “hz”.
*/
static void __mmc_set_clock(struct mmc_host *host, unsigned int hz)
{
WARN_ON(hz < host->f_min);
if (hz > host->f_max)
hz = host->f_max;
host->ios.clock = hz;
mmc_set_ios(host);
}
######把clock设置成传进的值
* Internal function that does the actual ios call to the host driver,
* optionally printing some debug output.
*/
static inline void mmc_set_ios(struct mmc_host *host)
{
struct mmc_ios *ios = &host->ios;
pr_debug(“%s: clock %uHz busmode %u powermode %u cs %u Vdd %u “
“width %u timing %u\n”,
mmc_hostname(host), ios->clock, ios->bus_mode,
ios->power_mode, ios->chip_select, ios->vdd,
ios->bus_width, ios->timing);
if (ios->clock > 0) //此时的clock如果不是0,那么clk_gate = false,
mmc_set_ungated(host); //只有0时才能再gate？
host->ops->set_ios(host, ios); //调用平台相关函数真正设置io
}
#####另外一个函数mmc_detect_change(host, 0);
#####在core.c中，
* mmc_detect_change – process change of state on a MMC socket
* @host: host which changed state.
* @delay: optional delay to wait before detection (jiffies)
*
* MMC drivers should call this when they detect a card has been
* inserted or removed. The MMC layer will confirm that any
* present card is still functional, and initialize any newly
* inserted.
*/
void mmc_detect_change(struct mmc_host *host, unsigned long delay)
{
#ifdef CONFIG_MMC_DEBUG
unsigned long flags;
spin_lock_irqsave(&host->lock, flags);
WARN_ON(host->removed);
spin_unlock_irqrestore(&host->lock, flags);
#endif
mmc_schedule_delayed_work(&host->detect, delay);
}
#####这个地方对应于上面alloc_host时候的mmc_rescan,
#####注册完毕执行一次探测，确认默认是否sd卡被插入，
#####而插入卡后中断触发也会执行到这里，下面直接看插卡后isr函数函数了，
#####在s3cmci.c中，
* ISR for the CardDetect Pin
*/
static irqreturn_t s3cmci_irq_cd(int irq, void *dev_id)
{
struct s3cmci_host *host = (struct s3cmci_host *)dev_id;
dbg(host, dbg_irq, “card detect\n”);
mmc_detect_change(host->mmc, msecs_to_jiffies(500));
return IRQ_HANDLED;
}
#####继续追下去，core.c中，
* mmc_detect_change – process change of state on a MMC socket
* @host: host which changed state.
* @delay: optional delay to wait before detection (jiffies)
*
* MMC drivers should call this when they detect a card has been
* inserted or removed. The MMC layer will confirm that any
* present card is still functional, and initialize any newly
* inserted.
*/
void mmc_detect_change(struct mmc_host *host, unsigned long delay)
{
#ifdef CONFIG_MMC_DEBUG
unsigned long flags;
spin_lock_irqsave(&host->lock, flags);
WARN_ON(host->removed);
spin_unlock_irqrestore(&host->lock, flags);
#endif
mmc_schedule_delayed_work(&host->detect, delay);
}
#####会调用mmc_schedule_delayed_work(&host->detect, delay);
#####host->detect这个延迟队列的初始化位于/drivers/mmc/core/host.c中，
#####INIT_DELAYED_WORK(&host->detect, mmc_rescan);
#####探测函数都会调用mmc_rescan这个系统提供的扫描sd卡函数，
#####核心扫描函数，下面就是重点的扫描卡函数了，放到下篇单独来说;
总结，概览了平台最相关的几个函数，接下来的都通用函数了，写的比较粗糙，还望见谅^.^!
