硬件設備：itop4412開發板 內核版本linux-3.8.1

設備樹方式減少了設備的冗余編碼，同時使移植變得更加高效。eMMC作為開發板的基礎，十分重要。

設備樹用的是內核自帶的smdk4412.dts

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

在設備樹中添加如下代碼：

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 };

在驅動中增加設備屬性匹配：

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內核驅動

編譯燒寫進開發板后啟動會出現錯誤：

mmc1: unrecognised EXT_CSD revision 7?

解決方法：將296行的6改為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 }

重新編譯后燒寫入開發板，啟動打印如下信息說明emmc驅動移植成功。

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命令查看詳細信息 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

總結

以上是生活随笔為你收集整理的设备树之emmc驱动移植的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。