Itop4412开发板emmc驱动移植（设备树）

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硬件设备：itop4412开发板内核版本linux-3.8.1

设备树方式减少了设备的冗余编码，同时使移植变得更加高效。eMMC作为开发板的基础，十分重要。

设备树用的是内核自带的smdk4412.dts

vim arch/arm/boot/dts/exynos4412-smdk4412.dts

在设备树中添加如下代码：

 87                 ldo22_reg: LDO22 { 88                                 regulator-name = "VMEM_VDD_2.8V"; 89                                 regulator-min-microvolt = <2800000>; 90                                 regulator-max-microvolt = <2800000>; 91                                 maxim,ena-gpios = <&gpk0 2 1>; 92                         };

146         mmc@12550000 {147         compatible = "samsung,exynos4412-dw-mshc";148                 reg = <0x12550000 0x1000>;149                 interrupts = <0 77 0>;150                 #address-cells = <1>;151                 #size-cells = <0>;152                 fifo-depth = <0x80>;153                 clocks = <&clock 301>, <&clock 149>;154                 clock-names = "biu", "ciu";155                 num-slots = <1>;156                 broken-cd;157                 non-removable;158                 card-detect-delay = <200>;159                 vmmc-supply = <&ldo22_reg>;160                 clock-frequency = <400000000>;161                 samsung,dw-mshc-ciu-div = <0>;162                 samsung,dw-mshc-sdr-timing = <2 3>;163                 samsung,dw-mshc-ddr-timing = <1 2>;164                 pinctrl-0 = <&sd4_clk &sd4_cmd &sd4_bus4 &sd4_bus8>;165                 pinctrl-names = "default";166                 status = "okay";167                 bus-width = <8>;168                 cap-mmc-highspeed;169         };

在驱动中增加设备属性匹配：

vim drivers/mmc/host/dw_mmc-exynos.c

221 static const struct of_device_id dw_mci_exynos_match[] = {222         { .compatible = "samsung,exynos4412-dw-mshc",},223         { .compatible = "samsung,exynos5250-dw-mshc",224                         .data = &exynos5250_drv_data, },225         {},226 };

make menuconfig 配置emmc内核驱动

编译烧写进开发板后启动会出现错误：

mmc1: unrecognised EXT_CSD revision 7

解决方法：将296行的6改为7

vim drivers/mmc/core/mmc.c

 295 /* amended by cqx:6->7  */ 296                 if (card->ext_csd.rev > 7) { 297                 pr_err("%s: unrecognised EXT_CSD revision %d\n", 298                         mmc_hostname(card->host), card->ext_csd.rev); 299                 err = -EINVAL; 300                 goto out; 301         }

重新编译后烧写入开发板，启动打印如下信息说明emmc驱动移植成功。

mmcblk0: mmc1:0001 4YMD3R 3.64 GiB

mmcblk0boot0: mmc1:0001 4YMD3R partition 1 4.00 MiB
mmcblk0boot1: mmc1:0001 4YMD3R partition 2 4.00 MiB
mmcblk0: p1 p2 p3 p4
mmcblk0boot1: unknown partition table
mmcblk0boot0: unknown partition table
mmc0: mmc_rescan_try_freq: trying to init card at 1562500 Hz
mmc0: new high speed SD card at address 0260

使用fdisk -l命令查看详细信息
Disk /dev/mmcblk0: 3909 MB, 3909091328 bytes
226 heads, 33 sectors/track, 1023 cylinders
Units = cylinders of 7458 * 512 = 3818496 bytes

Device Boot      Start         End      Blocks Id System
/dev/mmcblk0p1             653        1020     1372272   c Win95 FAT32 (LBA)
/dev/mmcblk0p2               6         287     1051578 83 Linux
/dev/mmcblk0p3             288         569     1051578 83 Linux
/dev/mmcblk0p4             570         652      309507 83 Linux

Partition table entries are not in disk order

Disk /dev/mmcblk0boot1: 4 MB, 4194304 bytes
4 heads, 16 sectors/track, 128 cylinders
Units = cylinders of 64 * 512 = 32768 bytes

Disk /dev/mmcblk0boot1 doesn't contain a valid partition table

Disk /dev/mmcblk0boot0: 4 MB, 4194304 bytes
4 heads, 16 sectors/track, 128 cylinders
Units = cylinders of 64 * 512 = 32768 bytes

Disk /dev/mmcblk0boot0 doesn't contain a valid partition table

Disk /dev/mmcblk1: 1992 MB, 1992294400 bytes
4 heads, 16 sectors/track, 60800 cylinders
Units = cylinders of 64 * 512 = 32768 bytes

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