Linux驱动——mmc bus浅析（五）

备注：
1. Kernel版本：5.4
2. 使用工具：Source Insight 4.0
3. 参考博客：
3. [mmc subsystem] mmc core（第三章）——bus模块说明

文章目录

Linux驱动——mmc bus浅析（五）
- 概述
- API预览
- - bus相关
  - mmc card相关
- 数据结构
- - mmc bus数据结构
  - sdio bus数据结构
- 核心接口实现
- - mmc_register_bus实现
  - sdio_register_bus实现
  - mmc_register_driver实现
  - sdio_register_driver实现
  - mmc_alloc_card实现
  - mmc_add_card实现

概述

对应代码

drivers/mmc/core/bus.c
drivers/mmc/core/sdio_bus.c

抽象出虚拟mmc/sdio bus，实现mmc/sdio bus的操作。

API预览

bus相关

mmc_register_bus & mmc_unregister_bus
用于注册和卸载mmc bus（虚拟mmc总线）到设备驱动模型中。

int mmc_register_bus(void);
void mmc_unregister_bus(void);

sdio_register_bus & sdio_unregister_bus

int sdio_register_bus(void);
void sdio_unregister_bus(void);

mmc card相关

mmc_alloc_card & mmc_release_card

用于分配或者释放一个struct mmc_card结构体，创建其于mmc host以及mmc bus之间的关联。

struct mmc_card *mmc_alloc_card(struct mmc_host *host, struct device_type *type);
static void mmc_release_card(struct device *dev);

mmc_add_card & mmc_remove_card
用于注册或者卸载struct mmc_card到mmc_bus上。

int mmc_add_card(struct mmc_card *card);
void mmc_remove_card(struct mmc_card *card);

数据结构

mmc bus数据结构

mmc_bus_type代表了mmc虚拟总线。其内容如下：

static struct bus_type mmc_bus_type = {.name        = "mmc",         // 相应会在/sys/bus下生成mmc目录// bus下的device下继承的属性，// 可以看到/sys/bus/mmc/devices/mmc0:0001/type属性就是这里来的.dev_groups    = mmc_dev_groups,.match        = mmc_bus_match,   // 用于mmc bus上device和driver的匹配.uevent        = mmc_bus_uevent,.probe        = mmc_bus_probe,   // 当match成功的时候，执行的probe操作.remove     = mmc_bus_remove,.shutdown = mmc_bus_shutdown,.pm     = &mmc_bus_pm_ops,     // 挂在mmc bus上的device的电源管理操作集合
};

mmc bus match方法

static int mmc_bus_match(struct device *dev, struct device_driver *drv)
{// 无条件返回1，说明挂载mmc bus上的// device（mmc_card）和driver（mmc_driver）是无条件匹配的。return 1;
}

mmc bus probe方法

static int mmc_bus_probe(struct device *dev)
{struct mmc_driver *drv = to_mmc_driver(dev->driver);struct mmc_card *card = mmc_dev_to_card(dev);// 直接调用mmc_driver中的probe操作，// 对于block.c来说就是mmc_blk_probereturn drv->probe(card);
}

sdio bus数据结构

sdio_bus_type代表了mmc虚拟总线。其内容如下：

static struct bus_type c = {.name       = "sdio",            // 相应会在/sys/bus下生成sdio目录.dev_groups = sdio_dev_groups,.match       = sdio_bus_match,  // 用于sdio bus上device和driver的匹配.uevent       = sdio_bus_uevent,.probe       = sdio_bus_probe,  // 当match成功的时候，执行的probe操作.remove     = sdio_bus_remove,.pm      = &sdio_bus_pm_ops,        // 挂在sdio bus上的device的电源管理操作集合
};

sdio bus match方法

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;
}static const struct sdio_device_id *sdio_match_device(struct sdio_func *func,struct sdio_driver *sdrv)
{const struct sdio_device_id *ids;// 获取sdio device 的ID tableids = sdrv->id_table;if (ids) {while (ids->class || ids->vendor || ids->device) {if (sdio_match_one(func, ids))//逐一排查class、vendor、device等IDreturn ids;ids++;}}return NULL;
}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);// 通过id_table来匹配if (sdio_match_device(func, sdrv))return 1;return 0;
}

sdio bus probe方法

static int sdio_bus_probe(struct device *dev)
{struct sdio_driver *drv = to_sdio_driver(dev->driver);struct sdio_func *func = dev_to_sdio_func(dev);const struct sdio_device_id *id;int ret;id = sdio_match_device(func, drv);//获取sdio device idif (!id)return -ENODEV;ret = dev_pm_domain_attach(dev, false);if (ret)return ret;atomic_inc(&func->card->sdio_funcs_probed);/* Unbound SDIO functions are always suspended.* During probe, the function is set active and the usage count* is incremented.  If the driver supports runtime PM,* it should call pm_runtime_put_noidle() in its probe routine and* pm_runtime_get_noresume() in its remove routine.*/if (func->card->host->caps & MMC_CAP_POWER_OFF_CARD) {ret = pm_runtime_get_sync(dev);if (ret < 0)goto disable_runtimepm;}/* Set the default block size so the driver is sure it's something* sensible. */sdio_claim_host(func);             // 获取host使用权if (mmc_card_removed(func->card))    // 移除cardret = -ENOMEDIUM;elseret = sdio_set_block_size(func, 0);sdio_release_host(func);         // 释放host使用权if (ret)goto disable_runtimepm;ret = drv->probe(func, id);          // 调用driver probe方法if (ret)goto disable_runtimepm;return 0;disable_runtimepm:atomic_dec(&func->card->sdio_funcs_probed);if (func->card->host->caps & MMC_CAP_POWER_OFF_CARD)pm_runtime_put_noidle(dev);dev_pm_domain_detach(dev, false);return ret;
}

核心接口实现

mmc_register_bus实现

int mmc_register_bus(void)
{return bus_register(&mmc_bus_type);
}void mmc_unregister_bus(void)
{bus_unregister(&mmc_bus_type);
}

我们将mmc_bus_type的这条bus称之为mmc_bus。
相关节点：/sys/bus/mmc。

sdio_register_bus实现

int sdio_register_bus(void)
{return bus_register(&sdio_bus_type);
}void sdio_unregister_bus(void)
{bus_unregister(&sdio_bus_type);
}

我们将sdio_bus_type的这条bus称之为sdio_bus。
相关节点：/sys/bus/sdio。

mmc_register_driver实现

用于注册struct mmc_driver *drv到mmc_bus上。mmc_driver就是mmc core抽象出来的card设备driver。

/*** mmc_register_driver - register a media driver*  @drv: MMC media driver*/
int mmc_register_driver(struct mmc_driver *drv)
{drv->drv.bus = &mmc_bus_type;return driver_register(&drv->drv);
}EXPORT_SYMBOL(mmc_register_driver);/**C*   mmc_unregister_driver - unregister a media driver*  @drv: MMC media driver*/
void mmc_unregister_driver(struct mmc_driver *drv)
{drv->drv.bus = &mmc_bus_type;driver_unregister(&drv->drv);
}

sdio_register_driver实现

int sdio_register_bus(void)
{return bus_register(&sdio_bus_type);
}void sdio_unregister_bus(void)
{bus_unregister(&sdio_bus_type);
}

mmc_alloc_card实现

用于分配一个struct mmc_card结构体，创建其于mmc host以及mmc bus之间的关联。

/** Allocate and initialise a new MMC card structure.*/
struct mmc_card *mmc_alloc_card(struct mmc_host *host, struct device_type *type)
{struct mmc_card *card;// 分配一个mmc_cardcard = kzalloc(sizeof(struct mmc_card), GFP_KERNEL);if (!card)return ERR_PTR(-ENOMEM);// 关联mmc_card与mmc_hostcard->host = host;device_initialize(&card->dev);// 设置card的device的parent device为mmc_host的classdev，// 注册到设备驱动模型中之后，// 会在/sys/class/mmc_host/mmc0目录下生成相应card的节点，如mmc0:0001card->dev.parent = mmc_classdev(host);// 设置card的bus为mmc_bus_type，这样，// mmc_card注册到设备驱动模型中之后就会挂在mmc_bus下。// 会在/sys/bus/mmc/devices/目录下生成相应card的节点，如mmc0:0001card->dev.bus = &mmc_bus_type;card->dev.release = mmc_release_card;// 设置device typecard->dev.type = type;return card;
}

mmc_add_card实现

用于注册struct mmc_card到mmc_bus上。

/** Register a new MMC card with the driver model.*/
int mmc_add_card(struct mmc_card *card)
{int ret;const char *type;const char *uhs_bus_speed_mode = "";static const char *const uhs_speeds[] = {[UHS_SDR12_BUS_SPEED] = "SDR12 ",[UHS_SDR25_BUS_SPEED] = "SDR25 ",[UHS_SDR50_BUS_SPEED] = "SDR50 ",[UHS_SDR104_BUS_SPEED] = "SDR104 ",[UHS_DDR50_BUS_SPEED] = "DDR50 ",};// 配置card dev name，将体现在/sys/bus/mmc/device/mmcx:xxx上dev_set_name(&card->dev, "%s:%04x", mmc_hostname(card->host), card->rca);// 匹配 card 类型switch (card->type) {case MMC_TYPE_MMC:type = "MMC";break;case MMC_TYPE_SD:type = "SD";if (mmc_card_blockaddr(card)) {if (mmc_card_ext_capacity(card))type = "SDXC";elsetype = "SDHC";}break;case MMC_TYPE_SDIO:type = "SDIO";break;case MMC_TYPE_SD_COMBO:type = "SD-combo";if (mmc_card_blockaddr(card))type = "SDHC-combo";break;default:type = "?";break;}if (mmc_card_uhs(card) &&(card->sd_bus_speed < ARRAY_SIZE(uhs_speeds)))uhs_bus_speed_mode = uhs_speeds[card->sd_bus_speed];// 打印 card 基本信息if (mmc_host_is_spi(card->host)) {pr_info("%s: new %s%s%s card on SPI\n",mmc_hostname(card->host),mmc_card_hs(card) ? "high speed " : "",mmc_card_ddr52(card) ? "DDR " : "",type);} else {pr_info("%s: new %s%s%s%s%s%s card at address %04x\n",mmc_hostname(card->host),mmc_card_uhs(card) ? "ultra high speed " :(mmc_card_hs(card) ? "high speed " : ""),mmc_card_hs400(card) ? "HS400 " :(mmc_card_hs200(card) ? "HS200 " : ""),mmc_card_hs400es(card) ? "Enhanced strobe " : "",mmc_card_ddr52(card) ? "DDR " : "",uhs_bus_speed_mode, type, card->rca);}#ifdef CONFIG_DEBUG_FS// 创建card对应的debug节点，对应路径例如：/sys/kernel/debug/mmc0/mmc0:0001mmc_add_card_debugfs(card);
#endifcard->dev.of_node = mmc_of_find_child_device(card->host, 0);device_enable_async_suspend(&card->dev);/* 添加到设备驱动模型中 */// 会创建/sys/bus/mmc/devices/mmc0:0001节点// 和/sys/class/mmc_host/mmc0/mmc0:0001节点ret = device_add(&card->dev);if (ret)return ret;/* 设置mmc card的state标识 */// 设置card的MMC_STATE_PRESENT状态// #define MMC_STATE_PRESENT    (1<<0)      /* present in sysfs */// 表示card已经合入到sysfs中了mmc_card_set_present(card);return 0;
}