块设备驱动2--sd卡驱动1(linux-3.2.36的sdchi.h分析)
我的经历：
看了某些大神的说明，我胆怯地进入了drivers/mmc/host/，看过我之前的文章知道我用的是s3c2440。
看驱动时，我首先会找s3c字样，于是我注意到sdhci-s3c.c和s3cmci.c。
看了一下Kconfig
config MMC_S3C
tristate "Samsung S3C SD/MMC Card Interface support"
depends on ARCH_S3C2410
help
This selects a driver for the MCI interface found in
Samsung's S3C2410, S3C2412, S3C2440, S3C2442 CPUs.
If you have a board based on one of those and a MMC/SD
slot, say Y or M here.
If unsure, say N.
再看Makefile
obj-$(CONFIG_MMC_S3C) += s3cmci.o
我想我用s3cmci就可以了。我就猜测s3cmci和sdhci-s3c就是寄存器不一样。但是当我看了看代码，不是这样。
记得大神说过struct mmc_host。sd驱动用到的主要结构，但是sdhci-s3c用到的是struct sdhci_host。
这是什么情况。
首先我就考虑sdhci到底是什么，我看所有sdhci-*.c驱动都用到了sdhci.c，我看到sdhci.c对寄存器操作的偏移都
是一样的，这样我想到了usb的ochi驱动。应该有个sd控制器都遵循的协议。
然后我又打开了s3c6410的datasheet
第一行 SD Standard Host很耀眼。最后我在百度找的了这个：
Part_A2_SD_Host_Controller_Simplified_Specification_Ver2.00.pdf
这个就是所说的协议，sdhci.c要实现的东西。s3c2440并不遵循这个。
先看看sdhci吧，看c之前先看.h文件分析
/* * linux/include/linux/mmc/sdhci.h - Secure Digital Host Controller Interface * * Copyright (C) 2005-2008 Pierre Ossman, All Rights Reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or (at * your option) any later version. */#ifndef LINUX_MMC_SDHCI_H#define LINUX_MMC_SDHCI_H#include <linux/scatterlist.h>#include <linux/compiler.h>#include <linux/types.h>#include <linux/io.h>#include <linux/mmc/host.h>struct sdhci_host {/* Data set by hardware interface driver */const char *hw_name;/* Hardware bus name */ //硬件总线名unsigned int quirks;/* Deviations from spec. */ //偏离规范//我们看有哪些怪癖，还有代码会如何处理/* Controller doesn't honor resets unless we touch the clock register */#define SDHCI_QUIRK_CLOCK_BEFORE_RESET(1<<0)/*SDHCI_QUIRK_CLOCK_BEFORE_RESET 是有的要在复位前设置时钟寄存器会在复位前调用host->ops->set_clock(host, clock);驱动提供*//* Controller has bad caps bits, but really supports DMA */#define SDHCI_QUIRK_FORCE_DMA(1<<1)/* if (host->quirks & SDHCI_QUIRK_FORCE_DMA) host->flags |= SDHCI_USE_SDMA;就是支持SDMA*//* Controller doesn't like to be reset when there is no card inserted. */#define SDHCI_QUIRK_NO_CARD_NO_RESET(1<<2)/*上面英文已说的很清楚：没有卡插入时，控制器不想复位。在复位时遇到这个标准，会想尝试读当前的状态，成功返回，失败进行复位。*//* Controller doesn't like clearing the power reg before a change */#define SDHCI_QUIRK_SINGLE_POWER_WRITE(1<<3)/*控制器不想清除电源寄存器在一个改变MMC_VDD前。遇到这个，直接改电源寄存器值，不清除。*//* Controller has flaky internal state so reset it on each ios change */#define SDHCI_QUIRK_RESET_CMD_DATA_ON_IOS(1<<4)/*在sdhci_do_set_ios()中会用到。解释：有些控制器在一些操作时会发疯，即使是CMD0,解决方法就是复位每一个ios.*//* Controller has an unusable DMA engine */#define SDHCI_QUIRK_BROKEN_DMA(1<<5)//控制器有一个无法使用的DMA引擎//SDMA: secure DMA //ADMA: advanced DMA /* Controller has an unusable ADMA engine */#define SDHCI_QUIRK_BROKEN_ADMA(1<<6)//控制器有一个无法使用的ADMA引擎/* Controller can only DMA from 32-bit aligned addresses */#define SDHCI_QUIRK_32BIT_DMA_ADDR(1<<7)//DMA要32位地址对齐/* Controller can only DMA chunk sizes that are a multiple of 32 bits */#define SDHCI_QUIRK_32BIT_DMA_SIZE(1<<8)//DMA的大小是32的倍数/* Controller can only ADMA chunks that are a multiple of 32 bits */#define SDHCI_QUIRK_32BIT_ADMA_SIZE(1<<9)//ADMA的大小是32的倍数//遇到这些地址和大小限制，会先判断数据。/* Controller needs to be reset after each request to stay stable */#define SDHCI_QUIRK_RESET_AFTER_REQUEST(1<<10)//每个请求之后控制器需要复位来保持稳定/*在sdhci_tasklet_finish()中，即任务完成时，当host->quirks & SDHCI_QUIRK_RESET_AFTER_REQUEST成立时，执行复位。*//* Controller needs voltage and power writes to happen separately */#define SDHCI_QUIRK_NO_SIMULT_VDD_AND_POWER(1<<11)/*这个标准是开启电源时，要先设置电压。Marvell CaFe的芯片就是如此代码，先设置，再或上SDHCI_POWER_ON开启 if (host->quirks & SDHCI_QUIRK_NO_SIMULT_VDD_AND_POWER) sdhci_writeb(host, pwr, SDHCI_POWER_CONTROL); pwr |= SDHCI_POWER_ON; sdhci_writeb(host, pwr, SDHCI_POWER_CONTROL);*//* Controller provides an incorrect timeout value for transfers */#define SDHCI_QUIRK_BROKEN_TIMEOUT_VAL(1<<12)//控制器提供一个不正确的超时值。/*会用0xE作为timeout.就是让硬件有个长的超时值，比短的好。 if (host->quirks & SDHCI_QUIRK_BROKEN_TIMEOUT_VAL) return 0xE;*//* Controller has an issue with buffer bits for small transfers */#define SDHCI_QUIRK_BROKEN_SMALL_PIO(1<<13)//控制器支持小字节传输//有些控制器（例如：JMicron JMB38x)弄乱传输位，（小于4字节）。//只要它有一个block,我们可以忽略这些位。//寄存器PRNSTS(s3c6410有这个寄存器)的第11位(buffer read enable)会被忽略/* Controller does not provide transfer-complete interrupt when not busy */#define SDHCI_QUIRK_NO_BUSY_IRQ(1<<14)//当忙的时候，控制器不提供传输完成中断//如果忙的话，linux会执行下面的代码/* if (intmask & SDHCI_INT_RESPONSE) sdhci_finish_command(host);*//* Controller has unreliable card detection */#define SDHCI_QUIRK_BROKEN_CARD_DETECTION(1<<15)//不可靠的卡检测/*sdhci_set_card_detection()函数会判断返回： if (host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION) return;*//* Controller reports inverted write-protect state */#define SDHCI_QUIRK_INVERTED_WRITE_PROTECT(1<<16)/*报告反的写保护状态值：sdhci_check_ro()函数： return host->quirks & SDHCI_QUIRK_INVERTED_WRITE_PROTECT ? !is_readonly : is_readonly;*//* Controller has nonstandard clock management */#define SDHCI_QUIRK_NONSTANDARD_CLOCK(1<<17)//非标准时钟管理//不标准，你就自己搞吧/*sdhci_set_clock()if (host->ops->set_clock) { host->ops->set_clock(host, clock); if (host->quirks & SDHCI_QUIRK_NONSTANDARD_CLOCK) return; }*//* Controller does not like fast PIO transfers */#define SDHCI_QUIRK_PIO_NEEDS_DELAY(1<<18)//pio需要延时//要延时就给他延时/*sdhci_transfer_pio()中 if (host->quirks & SDHCI_QUIRK_PIO_NEEDS_DELAY) udelay(100);*//* Controller losing signal/interrupt enable states after reset */#define SDHCI_QUIRK_RESTORE_IRQS_AFTER_RESET(1<<19)//复位后会丢掉信号/中断使能状态/*在sdhci_reset()中，先读出中断使能状态 if (host->quirks & SDHCI_QUIRK_RESTORE_IRQS_AFTER_RESET) ier = sdhci_readl(host, SDHCI_INT_ENABLE);复位完再设置一下 if (host->quirks & SDHCI_QUIRK_RESTORE_IRQS_AFTER_RESET) sdhci_clear_set_irqs(host, SDHCI_INT_ALL_MASK, ier);*//* Controller has to be forced to use block size of 2048 bytes */#define SDHCI_QUIRK_FORCE_BLK_SZ_2048(1<<20)//控制器被迫使用2048字节的块大小/* if (host->quirks & SDHCI_QUIRK_FORCE_BLK_SZ_2048) { mmc->max_blk_size = 2;*//* Controller cannot do multi-block transfers */#define SDHCI_QUIRK_NO_MULTIBLOCK(1<<21)//不能多块处理/*sdhci_add_host()中 //Maximum block count. mmc->max_blk_count = (host->quirks & SDHCI_QUIRK_NO_MULTIBLOCK) ? 1 : 65535;可以看一下spec,有三种：Single Block, Multi Block, Infinite Block.*//* Controller can only handle 1-bit data transfers */#define SDHCI_QUIRK_FORCE_1_BIT_DATA(1<<22)//一位数据传输//不是1位就4位/* if (!(host->quirks & SDHCI_QUIRK_FORCE_1_BIT_DATA)) mmc->caps |= MMC_CAP_4_BIT_DATA;在这段代码之前有一句：一个控制器可以支持8位宽度，但板子本身可能没有引脚引出。板支持8位宽度必须在自己的平台代码调用sdhci_add_host()之前,设置“MMC->caps |= MMC_CAP_8_BIT_DATA;”对于8-bits不是同一的代码处理通过sdhci_ops的platform_8bit_width(函数指针)自己处理。*//* Controller needs 10ms delay between applying power and clock */#define SDHCI_QUIRK_DELAY_AFTER_POWER(1<<23)//设置电源和时钟之间要10ms延时/*sdhci_set_power() if (host->quirks & SDHCI_QUIRK_DELAY_AFTER_POWER) mdelay(10);*//* Controller uses SDCLK instead of TMCLK for data timeouts */#define SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK(1<<24)//用SDCLK代替TMCLK作为数据超时//SDCLK是sd总线时钟//TMCLK是专门为了检测超时的时钟/* Controller reports wrong base clock capability */#define SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN(1<<25)//基本时钟功能报错/* if (host->max_clk == 0 || host->quirks & SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN) { if (!host->ops->get_max_clock) { pr_err("%s: Hardware doesn't specify base clock " "frequency.\n", mmc_hostname(mmc)); return -ENODEV; } host->max_clk = host->ops->get_max_clock(host); }可以看出max_clk为0时，我们可以通过host->ops->get_max_clock()获得*//* Controller cannot support End Attribute in NOP ADMA descriptor */#define SDHCI_QUIRK_NO_ENDATTR_IN_NOPDESC(1<<26)//不支持NOP ADMA属性/*在sdhci_adma_table_pre()中如果有此标志就不调用 // nop, end, valid sdhci_set_adma_desc(desc, 0, 0, 0x3);*//* Controller is missing device caps. Use caps provided by host */#define SDHCI_QUIRK_MISSING_CAPS(1<<27)//缺少设备caps，使用主机的caps/*sdhci_add_host() caps[0] = (host->quirks & SDHCI_QUIRK_MISSING_CAPS) ? host->caps : sdhci_readl(host, SDHCI_CAPABILITIES);*//* Controller uses Auto CMD12 command to stop the transfer */#define SDHCI_QUIRK_MULTIBLOCK_READ_ACMD12(1<<28)//spec中说的Auto CMD12(停止命令)/*最终会通过mode写到寄存里sdhci_writew(host, mode, SDHCI_TRANSFER_MODE);*//* Controller doesn't have HISPD bit field in HI-SPEED SD card */#define SDHCI_QUIRK_NO_HISPD_BIT(1<<29)//没有HISPD位//这个会通过ctrl写入/* sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);*//* Controller treats ADMA descriptors with length 0000h incorrectly */#define SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC(1<<30)//长度为0的ADAM描述符认为不正确/* if (host->quirks & SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC) mmc->max_seg_size = 65535; else mmc->max_seg_size = 65536;这个max_seg_size是做分散/聚合是每个条目不能大于64k*//* The read-only detection via SDHCI_PRESENT_STATE register is unstable */#define SDHCI_QUIRK_UNSTABLE_RO_DETECT(1<<31)//通过PRESENT_STATE寄存器检测read-only是不准的//如果这样就多次检测/* ro_count = 0; for (i = 0; i < SAMPLE_COUNT; i++) { if (sdhci_check_ro(host)) { if (++ro_count > SAMPLE_COUNT / 2) return 1; } msleep(30); }*/unsigned int quirks2;/* More deviations from spec. */#define SDHCI_QUIRK2_OWN_CARD_DETECTION(1<<0)//自己的卡检测/*和上面的SDHCI_QUIRK_BROKEN_CARD_DETECTION一样*/int irq;/* Device IRQ */ void __iomem *ioaddr;/* Mapped address */const struct sdhci_ops *ops;/* Low level hw interface *//*主要是硬件操作接口struct sdhci_ops {#ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS u32 (*read_l)(struct sdhci_host *host, int reg); u16 (*read_w)(struct sdhci_host *host, int reg); u8 (*read_b)(struct sdhci_host *host, int reg); void (*write_l)(struct sdhci_host *host, u32 val, int reg); void (*write_w)(struct sdhci_host *host, u16 val, int reg); void (*write_b)(struct sdhci_host *host, u8 val, int reg);#endif上面你不设置就使用内核提供的readl等 void (*set_clock)(struct sdhci_host *host, unsigned int clock);//设置时钟 int (*enable_dma)(struct sdhci_host *host);//使能dma unsigned int (*get_max_clock)(struct sdhci_host *host);//获取最大时钟 unsigned int (*get_min_clock)(struct sdhci_host *host);//获取最小时钟 unsigned int (*get_timeout_clock)(struct sdhci_host *host);//获得超时时钟 int (*platform_8bit_width)(struct sdhci_host *host, int width);//八位传输操作 void (*platform_send_init_74_clocks)(struct sdhci_host *host, u8 power_mode);//只在sdhci-pxav3.c看到使用，不清楚干嘛 unsigned int (*get_ro)(struct sdhci_host *host);//获取readonly状态 void (*platform_reset_enter)(struct sdhci_host *host, u8 mask);//复位之前处理 void (*platform_reset_exit)(struct sdhci_host *host, u8 mask);//复位之后处理 int (*set_uhs_signaling)(struct sdhci_host *host, unsigned int uhs);//uhs:Ultra High Speed 设置超高速信号 void (*hw_reset)(struct sdhci_host *host);//复位};*/struct regulator *vmmc;/* Power regulator *///电源调节器/* Internal data */struct mmc_host *mmc;/* MMC structure */ //大名鼎鼎的mmc结构u64 dma_mask;/* custom DMA mask */#if defined(CONFIG_LEDS_CLASS) || defined(CONFIG_LEDS_CLASS_MODULE)struct led_classdev led;/* LED control */char led_name[32];#endifspinlock_t lock;/* Mutex */int flags;/* Host attributes */#define SDHCI_USE_SDMA(1<<0)/* Host is SDMA capable */#define SDHCI_USE_ADMA(1<<1)/* Host is ADMA capable */#define SDHCI_REQ_USE_DMA(1<<2)/* Use DMA for this req. */#define SDHCI_DEVICE_DEAD(1<<3)/* Device unresponsive */#define SDHCI_SDR50_NEEDS_TUNING (1<<4)/* SDR50 needs tuning */#define SDHCI_NEEDS_RETUNING(1<<5)/* Host needs retuning */#define SDHCI_AUTO_CMD12(1<<6)/* Auto CMD12 support */#define SDHCI_AUTO_CMD23(1<<7)/* Auto CMD23 support */#define SDHCI_PV_ENABLED(1<<8)/* Preset value enabled */#define SDHCI_SDIO_IRQ_ENABLED(1<<9)/* SDIO irq enabled */unsigned int version;/* SDHCI spec. version *///版本,目前是1.0 2.0 3.0unsigned int max_clk;/* Max possible freq (MHz) */unsigned int timeout_clk;/* Timeout freq (KHz) */unsigned int clk_mul;/* Clock Muliplier value */unsigned int clock;/* Current clock (MHz) */u8 pwr;/* Current voltage */bool runtime_suspended;/* Host is runtime suspended */ //挂起标志struct mmc_request *mrq;/* Current request */struct mmc_command *cmd;/* Current command */struct mmc_data *data;/* Current data request */unsigned int data_early:1;/* Data finished before cmd *///数据管理完成在命令完成之前struct sg_mapping_iter sg_miter;/* SG state for PIO *///sg 状态unsigned int blocks;/* remaining PIO blocks */ //剩余PIO的blocksint sg_count;/* Mapped sg entries *///映射的SG项数目u8 *adma_desc;/* ADMA descriptor table */ //AMDA描述符表u8 *align_buffer;/* Bounce buffer */ //反弹缓冲dma_addr_t adma_addr;/* Mapped ADMA descr. table */dma_addr_t align_addr;/* Mapped bounce buffer */struct tasklet_struct card_tasklet;/* Tasklet structures *//*中断函数中：if (intmask & (SDHCI_INT_CARD_INSERT | SDHCI_INT_CARD_REMOVE))会调用tasklet_schedule(&host->card_tasklet); 可以看出是处理card insert和remove，对应的函数是 sdhci_tasklet_card()*/struct tasklet_struct finish_tasklet; /* sdhci_remove_host()函数，如果host->mrq不为NULL。就会调用tasklet_schedule(&host->finish_tasklet); 可以看出是有请求时sd被remove会执行的处理，对应的函数sdhci_tasklet_finish()；*/struct timer_list timer;/* Timer for timeouts *///超时定时器unsigned int caps;/* Alternative capabilities *///另类功能unsigned int ocr_avail_sdio;/* OCR bit masks */ //ocr 寄存器记录着支持的电压unsigned int ocr_avail_sd;unsigned int ocr_avail_mmc;//CMD19在SD spec中是预留的。在SDHCI v3.00中有个tuning command会用到wait_queue_head_tbuf_ready_int;/* Waitqueue for Buffer Read Ready interrupt *//*在 sdhci_data_irq()// CMD19 generates _only_ Buffer Read Ready interrupt if (intmask & SDHCI_INT_DATA_AVAIL) { if (SDHCI_GET_CMD(sdhci_readw(host, SDHCI_COMMAND)) == MMC_SEND_TUNING_BLOCK) { host->tuning_done = 1; wake_up(&host->buf_ready_int); return; } } 唤醒的函数是sdhci_execute_tuning()*/unsigned inttuning_done;/* Condition flag set when CMD19 succeeds *///CMD19成功标志unsigned inttuning_count;/* Timer count for re-tuning *///tuning计时unsigned inttuning_mode;/* Re-tuning mode supported by host *///tuning模式支持#define SDHCI_TUNING_MODE_10struct timer_listtuning_timer;/* Timer for tuning *///tuning用的定时器unsigned long private[0] ____cacheline_aligned;};#endif /* LINUX_MMC_SDHCI_H */