-
《Linux驱动：nand flash驱动看这一篇就够了》
一，前言
nand flash驱动开发总结，涉及到s3c2440芯片nand flash控制器的设置及操作、K9F2G08U0C nand flash的设置及操作、平台总线-驱动-设备模型等相关知识。
二，硬件电路
2.1 Nand flash相关
LDATA0~LDATA7：传输命令、地址和数据。
RnB：nand flash的工作状态，0表示就绪，1表示正忙。
CLE：决定DATA0~DATA7传输的是数据还是命令，1为命令，0为数据。
nFCE：nand flash的片选，1表示选中，0表示未选中（选中才能对其进行操作）。
ALE：决定DATA0~DATA7传输的是数据还是地址，1为地址，0为数据（CLE和ALE为0）。
nFWE：为0表示写操作（写命令、地址、数据）。
nFRE：为0表示读操作。
2.2 S3c2440相关
根据Nand Flash的芯片书册知，其需要五个字节表示地址，即五个地址周期，其一页的大小为2KB，8位数据/地址传输。根据S3c2440芯片书册可知，需要NCON、GPG13、GPG14为1，GPG15为0，即前者加上拉电阻，后者加下拉电阻。
2.3 Nand flash 位反转
由于Nand Flash的固有特性，在读写数据过程中，偶然会产生一位或几位数据错误（这种概率很低），bit位从“1”变为“0”，或者从“1”变为“0”。当位反转发生在关键的代码、数据上时，有可能导致系统崩溃。当仅仅是报告位反转，重新读取即可。如果确实发生了位反转，则必须有相应的错误检测/恢复措施。在NAND Flash上发生位反转的概率很高，推荐使用EDC/ECC进行错误检测和恢复。
三，Nand flash驱动框架
四，S3c2440 Nand Flash驱动的加载过程
S3c2440 Nand Flash驱动使用了平台总线-驱动-设备模型。
4.1 S3c2440 Nand Flash – 设备注册
linux-2.6.22.6/.config
CONFIG_ARCH_S3C2440=y- 1
linux-2.6.22.6/arch/arm/mach-s3c2440/mach-smdk2440.c
MACHINE_START(S3C2440, "SMDK2440") /* Maintainer: Ben Dooks- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
将上面的宏展开
static const struct machine_desc __mach_desc_SMDK2440 __attribute_used__ __attribute__((__section__(".arch.info.init"))) = { .nr = MACH_TYPE_SMDK2410, /* architecture number */ .name = "SMDK2440", /* architecture name */ /* Maintainer: Jonas Dietsche */ .phys_io = S3C2410_PA_UART, /* start of physical io */ .io_pg_offst = (((u32)S3C24XX_VA_UART) >> 18) & 0xfffc, .boot_params = S3C2410_SDRAM_PA + 0x100, /* tagged list */ .map_io = smdk2440_map_io, /* IO mapping function */ .init_irq = s3c24xx_init_irq, .init_machine = smdk2440_machine_init, .timer = &s3c24xx_timer, }- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
MACHINE_START主要是定义了"struct machine_desc"的类型，放在 section(“.arch.info.init”)，是初始化数据，Kernel 起来之后将被丢弃。
各个成员函数在不同时期被调用：- .init_machine 在 arch/arm/kernel/setup.c 中被 customize_machine 调用，放在 arch_initcall() 段里面，会自动按顺序被调用。
- init_irq在start_kernel() -> init_IRQ() -> init_arch_irq() 被调用
- map_io 在 setup_arch() -> paging_init() -> devicemaps_init()被调用
其他主要都在 setup_arch() 中用到。
系统初始化时，会调用smdk2440_machine_init
// linux-2.6.22.6/arch/arm/mach-s3c2440/mach-smdk2440.c static void __init smdk2440_machine_init(void) { s3c24xx_fb_set_platdata(&smdk2440_lcd_cfg); platform_add_devices(smdk2440_devices, ARRAY_SIZE(smdk2440_devices)); smdk_machine_init(); } // linux-2.6.22.6/arch/arm/plat-s3c24xx/common-smdk.c void __init smdk_machine_init(void) { ...... // 配置nand flash s3c_device_nand.dev.platform_data = &smdk_nand_info; ...... // 注册到平台总线 platform_add_devices(smdk_devs, ARRAY_SIZE(smdk_devs)); ...... } // 配置了nand flash各信号脉冲宽度或时间间隔，以及分区 static struct s3c2410_platform_nand smdk_nand_info = { .tacls = 20, .twrph0 = 60, .twrph1 = 20, .nr_sets = ARRAY_SIZE(smdk_nand_sets), .sets = smdk_nand_sets, }; // 设置nand flash的分区 static struct s3c2410_nand_set smdk_nand_sets[] = { [0] = { .name = "NAND", .nr_chips = 1, .nr_partitions = ARRAY_SIZE(smdk_default_nand_part), .partitions = smdk_default_nand_part, }, }; // 配置nand flash的具体分区，四个分区 static struct mtd_partition smdk_default_nand_part[] = { [0] = { .name = "bootloader", .size = 0x00040000, .offset = 0, }, [1] = { .name = "params", .offset = MTDPART_OFS_APPEND, .size = 0x00020000, }, [2] = { .name = "kernel", .offset = MTDPART_OFS_APPEND, .size = 0x00200000, }, [3] = { .name = "root", .offset = MTDPART_OFS_APPEND, .size = MTDPART_SIZ_FULL, } }; // linux-2.6.22.6/arch/arm/plat-s3c24xx/common-smdk.c static struct platform_device __initdata *smdk_devs[] = { &s3c_device_nand, ...... }; // linux-2.6.22.6/arch/arm/plat-s3c24xx/devs.c struct platform_device s3c_device_nand = { .name = "s3c2410-nand", .id = -1, .num_resources = ARRAY_SIZE(s3c_nand_resource), .resource = s3c_nand_resource, }; static struct resource s3c_nand_resource[] = { [0] = { .start = S3C2410_PA_NAND, .end = S3C2410_PA_NAND + S3C24XX_SZ_NAND - 1, .flags = IORESOURCE_MEM, } }; // 将s3c_device_nand设备注册到平台总线 // linux-2.6.22.6/drivers/base/platform.c int platform_add_devices(struct platform_device **devs, int num) { int i, ret = 0; for (i = 0; i < num; i++) { ret = platform_device_register(devs[i]); if (ret) { while (--i >= 0) platform_device_unregister(devs[i]); break; } } return ret; }- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
- 52
- 53
- 54
- 55
- 56
- 57
- 58
- 59
- 60
- 61
- 62
- 63
- 64
- 65
- 66
- 67
- 68
- 69
- 70
- 71
- 72
- 73
- 74
- 75
- 76
- 77
- 78
- 79
- 80
- 81
- 82
- 83
- 84
- 85
- 86
- 87
- 88
- 89
- 90
- 91
- 92
- 93
- 94
- 95
- 96
- 97
- 98
- 99
- 100
- 101
4.2 S3c2440 Nand Flash – 驱动注册
make menuconfig，将s3c2440 nand flash驱动加载到内核中，系统启动时便会自动加载驱动。
-> Device Drivers │ │ -> Memory Technology Device (MTD) support (MTD [=y]) │ │ -> NAND Device Support (MTD_NAND [=y]) │ │ <*> NAND Flash support for S3C2410/S3C2440 SoC │ │- 1
- 2
- 3
- 4
- 5
- 6
加载驱动，调用驱动初始化函数–s3c2410_nand_init
这里注册了三个nand flash驱动到平台总线。会根据注册到平台总线的nand flash设备进行匹配，选择使用哪个驱动。static int __init s3c2410_nand_init(void) { printk("S3C24XX NAND Driver, (c) 2004 Simtec Electronics\n"); platform_driver_register(&s3c2412_nand_driver); platform_driver_register(&s3c2440_nand_driver); return platform_driver_register(&s3c2410_nand_driver); } static struct platform_driver s3c2410_nand_driver = { .probe = s3c2410_nand_probe, .remove = s3c2410_nand_remove, .suspend = s3c24xx_nand_suspend, .resume = s3c24xx_nand_resume, .driver = { .name = "s3c2410-nand", .owner = THIS_MODULE, }, }; static struct platform_driver s3c2440_nand_driver = { .probe = s3c2440_nand_probe, .remove = s3c2410_nand_remove, .suspend = s3c24xx_nand_suspend, .resume = s3c24xx_nand_resume, .driver = { .name = "s3c2440-nand", .owner = THIS_MODULE, }, }; static struct platform_driver s3c2412_nand_driver = { .probe = s3c2412_nand_probe, .remove = s3c2410_nand_remove, .suspend = s3c24xx_nand_suspend, .resume = s3c24xx_nand_resume, .driver = { .name = "s3c2412-nand", .owner = THIS_MODULE, }, };- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
4.3 S3c2440 Nand Flash – 设备-驱动匹配
4.3.1 设备注册到平台总线时的匹配
platform_add_devices-> platform_device_register-> platform_device_add-> device_add-> bus_attach_device(dev)-> device_attach(dev)-> // 因为是注册到平台总线， // 所以从平台总线的驱动链表中取出每一个驱动和该设备进行匹配 bus_for_each_drv(dev->bus, NULL, dev, __device_attach)-> __device_attach-> driver_probe_device(drv, dev)-> // 因为是注册到平台总线，调用平台总线的匹配函数， // 即platform_match if (drv->bus->match && !drv->bus->match(dev, drv)) // 平台总线的匹配函数，通过比较驱动和设备的名称进行匹配 static int platform_match(struct device * dev, struct device_driver * drv) { struct platform_device *pdev = container_of(dev, struct platform_device, dev); return (strncmp(pdev->name, drv->name, BUS_ID_SIZE) == 0); }- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
4.3.2 驱动注册到平台总线时的匹配
platform_driver_register-> driver_register-> bus_add_driver-> driver_attach-> // 因为是注册到平台总线， // 所以从平台总线的设备链表中取出每一个设备和该驱动进行匹配 bus_for_each_dev(drv->bus, NULL, drv, __driver_attach)-> __driver_attach-> driver_probe_device-> // 因为是注册到平台总线，调用平台总线的匹配函数， // 即platform_match if (drv->bus->match && !drv->bus->match(dev, drv)) // 平台总线的匹配函数，通过比较驱动和设备的名称进行匹配 static int platform_match(struct device * dev, struct device_driver * drv) { struct platform_device *pdev = container_of(dev, struct platform_device, dev); return (strncmp(pdev->name, drv->name, BUS_ID_SIZE) == 0); }- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
4.4 S3c2440 Nand Flash – 调用驱动的probe函数
int driver_probe_device(struct device_driver * drv, struct device * dev) { int ret = 0; if (!device_is_registered(dev)) return -ENODEV; if (drv->bus->match && !drv->bus->match(dev, drv)) goto done; pr_debug("%s: Matched Device %s with Driver %s\n", drv->bus->name, dev->bus_id, drv->name); ret = really_probe(dev, drv); done: return ret; } // if (drv->bus->match && !drv->bus->match(dev, drv)) 匹配成功后调用really_probe函数 really_probe-> // 因为注册的是平台总线，所以看平台总线是否具有probe函数 // 如果平台总线具有probe函数则调用平台总线的probe函数,否则直接调用驱动的probe函数 if (dev->bus->probe) { ret = dev->bus->probe(dev); if (ret) goto probe_failed; } else if (drv->probe) { ret = drv->probe(dev); if (ret) goto probe_failed; } // 平台总线具有probe函数platform_drv_probe static int platform_drv_probe(struct device *_dev) { struct platform_driver *drv = to_platform_driver(_dev->driver); struct platform_device *dev = to_platform_device(_dev); // 调用驱动的probe函数 return drv->probe(dev); } // 设备 struct platform_device s3c_device_nand = { .name = "s3c2410-nand", .id = -1, .num_resources = ARRAY_SIZE(s3c_nand_resource), .resource = s3c_nand_resource, }; // 驱动 static struct platform_driver s3c2410_nand_driver = { .probe = s3c2410_nand_probe, .remove = s3c2410_nand_remove, .suspend = s3c24xx_nand_suspend, .resume = s3c24xx_nand_resume, .driver = { .name = "s3c2410-nand", .owner = THIS_MODULE, }, }; // 通过名称两者匹配，即调用s3c2410_nand_probe- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
- 52
- 53
- 54
- 55
- 56
- 57
- 58
- 59
- 60
五，驱动的probe函数分析
static int s3c2410_nand_probe(struct platform_device *dev) { return s3c24xx_nand_probe(dev, TYPE_S3C2410); }- 1
- 2
- 3
- 4
5.1 使能时钟
info->clk = clk_get(&pdev->dev, "nand"); if (IS_ERR(info->clk)) { dev_err(&pdev->dev, "failed to get clock"); err = -ENOENT; goto exit_error; } clk_enable(info->clk);- 1
- 2
- 3
- 4
- 5
- 6
- 7
5.2 端口映射
#define S3C2410_PA_NAND (0x4E000000) #define S3C24XX_SZ_NAND SZ_1M static struct resource s3c_nand_resource[] = { [0] = { .start = S3C2410_PA_NAND, .end = S3C2410_PA_NAND + S3C24XX_SZ_NAND - 1, .flags = IORESOURCE_MEM, } }; res = pdev->resource; size = res->end - res->start + 1; info->area = request_mem_region(res->start, size, pdev->name); if (info->area == NULL) { dev_err(&pdev->dev, "cannot reserve register region\n"); err = -ENOENT; goto exit_error; } info->regs = ioremap(res->start, size); if (info->regs == NULL) { dev_err(&pdev->dev, "cannot reserve register region\n"); err = -EIO; goto exit_error; }- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
5.3 s3c2440 nand flash控制器设置
5.3.1 设置脉冲宽度和间隔
static int s3c2410_nand_inithw(struct s3c2410_nand_info *info, struct platform_device *pdev) { struct s3c2410_platform_nand *plat = to_nand_plat(pdev); unsigned long clkrate = clk_get_rate(info->clk); int tacls_max = (info->cpu_type == TYPE_S3C2412) ? 8 : 4; int tacls, twrph0, twrph1; unsigned long cfg = 0; /* calculate the timing information for the controller */ clkrate /= 1000; /* turn clock into kHz for ease of use */ if (plat != NULL) { tacls = s3c_nand_calc_rate(plat->tacls, clkrate, tacls_max); twrph0 = s3c_nand_calc_rate(plat->twrph0, clkrate, 8); twrph1 = s3c_nand_calc_rate(plat->twrph1, clkrate, 8); } else { /* default timings */ tacls = tacls_max; twrph0 = 8; twrph1 = 8; } if (tacls < 0 || twrph0 < 0 || twrph1 < 0) { dev_err(info->device, "cannot get suitable timings\n"); return -EINVAL; } dev_info(info->device, "Tacls=%d, %dns Twrph0=%d %dns, Twrph1=%d %dns\n", tacls, to_ns(tacls, clkrate), twrph0, to_ns(twrph0, clkrate), twrph1, to_ns(twrph1, clkrate)); switch (info->cpu_type) { case TYPE_S3C2410: cfg = S3C2410_NFCONF_EN; cfg |= S3C2410_NFCONF_TACLS(tacls - 1); cfg |= S3C2410_NFCONF_TWRPH0(twrph0 - 1); cfg |= S3C2410_NFCONF_TWRPH1(twrph1 - 1); break; case TYPE_S3C2440: case TYPE_S3C2412: cfg = S3C2440_NFCONF_TACLS(tacls - 1); cfg |= S3C2440_NFCONF_TWRPH0(twrph0 - 1); cfg |= S3C2440_NFCONF_TWRPH1(twrph1 - 1); /* enable the controller and de-assert nFCE */ // 使能 nand flash控制器 writel(S3C2440_NFCONT_ENABLE, info->regs + S3C2440_NFCONT); } dev_dbg(info->device, "NF_CONF is 0x%lx\n", cfg); writel(cfg, info->regs + S3C2410_NFCONF); return 0; }- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
- 52
- 53
- 54
- 55
- 56
5.4 设置struct nand_chip
static void s3c2410_nand_init_chip(struct s3c2410_nand_info *info, struct s3c2410_nand_mtd *nmtd, struct s3c2410_nand_set *set) { struct nand_chip *chip = &nmtd->chip; void __iomem *regs = info->regs; // 提供nand flash读写数据接口 chip->write_buf = s3c2410_nand_write_buf; chip->read_buf = s3c2410_nand_read_buf; // 提供nand flash 片选接口 chip->select_chip = s3c2410_nand_select_chip; chip->chip_delay = 50; chip->priv = nmtd; chip->options = 0; chip->controller = &info->controller; switch (info->cpu_type) { case TYPE_S3C2410: // 提供 nand flash控制器数据写入的寄存器地址 chip->IO_ADDR_W = regs + S3C2410_NFDATA; info->sel_reg = regs + S3C2410_NFCONF; info->sel_bit = S3C2410_NFCONF_nFCE; // 提供nand flash 写命令或者地址接口 chip->cmd_ctrl = s3c2410_nand_hwcontrol; // 提供nand flash 判断就绪或忙状态接口 chip->dev_ready = s3c2410_nand_devready; break; ...... if (readl(regs + S3C2410_NFCONF) & S3C2412_NFCONF_NANDBOOT) dev_info(info->device, "System booted from NAND\n"); break; } // 提供 nand flash控制器数据读取的寄存器地址 chip->IO_ADDR_R = chip->IO_ADDR_W; nmtd->info = info; nmtd->mtd.priv = chip; nmtd->mtd.owner = THIS_MODULE; // 设置分区信息 nmtd->set = set; // 使用硬件ecc校验还是软件ecc校验，以解决位反转问题。这里使用软件ecc if (hardware_ecc) { ...... } else { chip->ecc.mode = NAND_ECC_SOFT; } }- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
- 52
- 53
- 54
- 55
- 56
5.5 nand_scan流程分析
nand_scan(&nmtd->mtd, (sets) ? sets->nr_chips : 1) -> nand_scan_ident(mtd, maxchips) -> // 设置默认的nand flash接口， // 比如设置struct nand_chip时提供的nand flash读写数据接口等 // 像5.4小节事先提供了则使用提供的，否则使用默认的 nand_set_defaults(chip, busw); // 从nand flash中读出其设备id ,和nand_flash_ids数组中定义的各型号flash信息对比， // 得到其flash型号。比如读到K9F2G08U0C nand flash的设备Id为da, // 则从nand_flash_ids数组中可得其信息为 // {"NAND 256MiB 3,3V 8-bit", 0xDA, 0, 256, 0, LP_OPTIONS}, nand_get_flash_type(mtd, chip, busw, &nand_maf_id); // 填充所有未初始化的函数指针(比如nand_erase等接口),并在适当的情况下扫描坏的块表。 nand_scan_tail(mtd);- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
5.6 添加分区
5.6.1 遍历mtd_notifiers，通过其add接口添加分区
s3c2410_nand_add_partition -> // 在s3c2410_nand_init_chip函数中已经将分区信息设置给了mtd add_mtd_device(&mtd->mtd) -> // 遍历mtd_notifiers，通过其add接口添加分区 list_for_each(this, &mtd_notifiers) { struct mtd_notifier *not = list_entry(this, struct mtd_notifier, list); not->add(mtd); }- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
5.6.2 设置mtd_notifiers链表
5.6.2.1 nand flash 字符设备
// linux-2.6.22.6/drivers/mtd/mtdchar.c init_mtdchar -> register_mtd_user(¬ifier) -> list_add(&new->list, &mtd_notifiers); static struct mtd_notifier notifier = { .add = mtd_notify_add, .remove = mtd_notify_remove, }; static void mtd_notify_add(struct mtd_info* mtd) { if (!mtd) return; // 创建字符设备 设备节点为/dev/mtd%d class_device_create(mtd_class, NULL, MKDEV(MTD_CHAR_MAJOR, mtd->index*2), NULL, "mtd%d", mtd->index); // 创建字符设备 设备节点为/dev/mtd%dro (只读) class_device_create(mtd_class, NULL, MKDEV(MTD_CHAR_MAJOR, mtd->index*2+1), NULL, "mtd%dro", mtd->index); }- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
5.6.2.2 nand flash的块设备
// linux-2.6.22.6/drivers/mtd/mtd_blkdevs.c register_mtd_blktrans-> register_mtd_user(&blktrans_notifier) -> list_add(&new->list, &mtd_notifiers); static struct mtd_notifier blktrans_notifier = { .add = blktrans_notify_add, .remove = blktrans_notify_remove, }; static void blktrans_notify_add(struct mtd_info *mtd) { struct list_head *this; if (mtd->type == MTD_ABSENT) return; list_for_each(this, &blktrans_majors) { struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list); tr->add_mtd(tr, mtd); } } blktrans_notify_add -> // 遍历blktrans_majors 通过其add_mtd函数添加分区 list_for_each(this, &blktrans_majors) { struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list); tr->add_mtd(tr, mtd); } // 设置blktrans_majors链表 两个地方设置，一个mtdblock_ro.c 一个mtdblock.c // linux-2.6.22.6/drivers/mtd/mtdblock_ro.c mtdblock_init-> register_mtd_blktrans(&mtdblock_tr) -> list_add(&tr->list, &blktrans_majors); static struct mtd_blktrans_ops mtdblock_tr = { .name = "mtdblock", .major = 31, .part_bits = 0, .blksize = 512, .readsect = mtdblock_readsect, .writesect = mtdblock_writesect, .add_mtd = mtdblock_add_mtd, .remove_dev = mtdblock_remove_dev, .owner = THIS_MODULE, }; mtdblock_add_mtd -> add_mtd_blktrans_dev(dev); alloc_disk(1 << tr->part_bits); set_capacity(gd, (new->size * tr->blksize) >> 9); add_disk(gd); // linux-2.6.22.6/drivers/mtd/mtdblock.c init_mtdblock -> register_mtd_blktrans(&mtdblock_tr); list_add(&tr->list, &blktrans_majors); static struct mtd_blktrans_ops mtdblock_tr = { .name = "mtdblock", .major = 31, .part_bits = 0, .blksize = 512, .open = mtdblock_open, .flush = mtdblock_flush, .release = mtdblock_release, .readsect = mtdblock_readsect, .writesect = mtdblock_writesect, .add_mtd = mtdblock_add_mtd, .remove_dev = mtdblock_remove_dev, .owner = THIS_MODULE, }; mtdblock_add_mtd -> add_mtd_blktrans_dev(dev)-> alloc_disk(1 << tr->part_bits); set_capacity(gd, (new->size * tr->blksize) >> 9); add_disk(gd);- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
- 52
- 53
- 54
- 55
- 56
- 57
- 58
- 59
- 60
- 61
- 62
- 63
- 64
- 65
- 66
- 67
- 68
- 69
- 70
- 71
- 72
- 73
- 74
- 75
- 76
- 77
- 78
- 79
- 80
- 81
- 82
- 83
- 84
5.6.3 块设备初始化请求队列
// linux-2.6.22.6/drivers/mtd/mtdblock.c init_mtdblock -> register_mtd_blktrans(&mtdblock_tr); tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock); // linux-2.6.22.6/drivers/mtd/mtdblock_ro.c mtdblock_init-> register_mtd_blktrans(&mtdblock_tr) -> tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
六，总结
6.1 nand flash字符设备创建过程
系统启动，内核初始化时加载mtdchar模块，调用init_mtdchar，将 struct mtd_notifier 结构注册到mtd_notifiers链表中，供后续nand flash驱动程序使用。
// linux-2.6.22.6/drivers/mtd/mtdchar.c init_mtdchar -> register_mtd_user(¬ifier) -> list_add(&new->list, &mtd_notifiers); static struct mtd_notifier notifier = { .add = mtd_notify_add, .remove = mtd_notify_remove, }; static void mtd_notify_add(struct mtd_info* mtd) { if (!mtd) return; // 创建字符设备 设备节点为/dev/mtd%d class_device_create(mtd_class, NULL, MKDEV(MTD_CHAR_MAJOR, mtd->index*2), NULL, "mtd%d", mtd->index); // 创建字符设备 设备节点为/dev/mtd%dro (只读) class_device_create(mtd_class, NULL, MKDEV(MTD_CHAR_MAJOR, mtd->index*2+1), NULL, "mtd%dro", mtd->index); }- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
nand flash驱动程序，调用s3c2410_nand_add_partition接口添加分区时，调用struct mtd_notifier结构中的add函数添加分区，创建字符设备节点。
s3c2410_nand_add_partition -> // 在s3c2410_nand_init_chip函数中已经将分区信息设置给了mtd add_mtd_device(&mtd->mtd) -> // 遍历mtd_notifiers，通过其add接口添加分区 list_for_each(this, &mtd_notifiers) { struct mtd_notifier *not = list_entry(this, struct mtd_notifier, list); not->add(mtd); }- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
6.2 nand flash块设备创建过程
系统启动，内核初始化时加载mtdblock模块，调用init_mtdblock，将struct mtd_notifier 结构注册到mtd_notifiers链表中，注册块设备，初始化请求队列，注册struct mtd_blktrans_ops结构到blktrans_majors链表，供后续nand flash驱动程序使用。(mtdblock_ro.c 和 mtdblock.c类似操作)
init_mtdblock -> register_mtd_blktrans(&mtdblock_tr) -> // 将struct mtd_notifier 结构注册到mtd_notifiers链表中 if (!blktrans_notifier.list.next) register_mtd_user(&blktrans_notifier); // 注册块设备 /dev/mtdblock ret = register_blkdev(tr->major, tr->name); // 初始化请求队列 tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock); // 注册struct mtd_blktrans_ops结构到blktrans_majors链表 list_add(&tr->list, &blktrans_majors); static struct mtd_notifier blktrans_notifier = { .add = blktrans_notify_add, .remove = blktrans_notify_remove, }; static void blktrans_notify_add(struct mtd_info *mtd) { struct list_head *this; if (mtd->type == MTD_ABSENT) return; list_for_each(this, &blktrans_majors) { struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list); tr->add_mtd(tr, mtd); } } static struct mtd_blktrans_ops mtdblock_tr = { .name = "mtdblock", .major = 31, .part_bits = 0, .blksize = 512, .open = mtdblock_open, .flush = mtdblock_flush, .release = mtdblock_release, .readsect = mtdblock_readsect, .writesect = mtdblock_writesect, .add_mtd = mtdblock_add_mtd, .remove_dev = mtdblock_remove_dev, .owner = THIS_MODULE, };- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
nand flash驱动程序，调用s3c2410_nand_add_partition接口添加分区时，调用struct mtd_notifier结构中的add函数添加分区，调用struct mtd_notifier结构中的add函数（blktrans_notify_add），即调用struct mtd_blktrans_ops结构中的add_mtd函数（mtdblock_add_mtd）。
s3c2410_nand_add_partition -> // 在s3c2410_nand_init_chip函数中已经将分区信息设置给了mtd add_mtd_device(&mtd->mtd) -> // 遍历mtd_notifiers，通过其add接口添加分区 list_for_each(this, &mtd_notifiers) { struct mtd_notifier *not = list_entry(this, struct mtd_notifier, list); not->add(mtd); } blktrans_notify_add -> mtdblock_add_mtd -> add_mtd_blktrans_dev(dev)-> alloc_disk(1 << tr->part_bits); set_capacity(gd, (new->size * tr->blksize) >> 9); add_disk(gd);- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
6.3 一次应用层读取Nand Flash数据的过程
// 对块设备节点/dev/mtdblock进行访问操作 //一个读数据的bio，被合并或被生成一个请求，触发请求队列的请求处理函数 mtd_blktrans_request -> // 唤醒一个休眠线程--mtd_blktrans_thread，该线程在register_mtd_blktrans中启动 wake_up_process(tr->blkcore_priv->thread); // 该线程从请求队列中取出一个请求调用do_blktrans_request接口进行处理 mtd_blktrans_thread do_blktrans_request -> //tr->readsect 即 struct mtd_blktrans_ops 中的 mtdblock_readsect接口 tr->readsect(dev, block, buf) -> do_cached_read(mtdblk, block<<9, 512, buf) -> //mtd->read 即 struct mtd_info中的 nand_read接口 //在 nand_scan_tail接口中被设置 mtd->read = nand_read; mtd->read(mtd, pos, size, &retlen, buf) -> nand_do_read_ops(mtd, from, &chip->ops) -> chip->ecc.read_page_raw(mtd, chip, bufpoi) -> nand_read_page_raw -> // chip->read_buf 即 s3c2410_nand_read_buf // 在驱动程序中 s3c2410_nand_init_chip函数里设置 // chip->read_buf = s3c2410_nand_read_buf; chip->read_buf(mtd, buf, mtd->writesize); chip->read_buf(mtd, chip->oob_poi, mtd->oobsize) -> // 从nand flash控制器的NFDATA寄存器中读取数据 // chip->IO_ADDR_W = regs + S3C2410_NFDATA; // chip->IO_ADDR_R = chip->IO_ADDR_W; readsb(this->IO_ADDR_R, buf, len);- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
-
相关阅读:
外卖项目（SpringBoot）--- 项目优化 [读写分离、Nginx使用]
用户忠诚度衡量指标丨利用净推荐值减少流失
制造不可靠的系统
娄底医药工业洁净厂建设基本要点概述
flutter dio 网络封装。记录
【雅思阅读】王希伟阅读P4（matching2段落信息配对题【困难】）
覆盖接入2w+交通监测设备，EMQ为深圳市打造交通全要素数字化新引擎
Js实现前端分页器
带妹妹学密码系列二（基础知识篇）
前端内容记录之常用置标
- 原文地址：https://blog.csdn.net/qq_40709487/article/details/126808923
