為uboot添加網卡功能可以讓uboot通過tftp下載內核, 方便我們的開發, 對於網卡功能的移植,我們依然在在一遍又一遍的實踐這個uboot改造的套路。
- 找運行邏輯，即插入代碼的位置。
- 根據運行邏輯編寫功能代碼。
- 找配置邏輯，即修改哪些文件使配置生效。
- 根據配置邏輯修改配置使功能代碼生效。
- 重新編譯燒寫uboot。
1. 找運行邏輯
為了實現ping、tftp下載、nfs掛載等功能，必須將uboot的網卡功能配置上，這個功能屬於板級功能，
看README+經驗+樣板
需要在相應板級目錄的xxx.c中配置，所以我們找到了"board/samsung/xboot/xboot.c"，這個文件的入口是board_init()，即1.找到了運行邏輯。
24 /*
25 * netdev.h - definitions an prototypes for network devices
26 */
31 /*
32 * Board and CPU-specific initialization functions
33 * board_eth_init() has highest priority. cpu_eth_init() only
34 * gets called if board_eth_init() isn't instantiated or fails.
35 * Return values:
36 * 0: success
37 * -1: failure
38 */
39
40 int board_eth_init(bd_t *bis);
41 int cpu_eth_init(bd_t *bis);
56 int dm9000_initialize(bd_t *bis);
//doc/README.drivers.eth
17 ----------
18 Register
19 ----------
20
21 When U-Boot initializes, it will call the common function eth_initialize().
22 This will in turn call the board-specific board_eth_init() (or if that fails,
23 the cpu-specific cpu_eth_init()). These board-specific functions can do random
24 system handling, but ultimately they will call the driver-specific register
25 function which in turn takes care of initializing that particular instance.
26
27 Keep in mind that you should code the driver to avoid storing state in global
28 data as someone might want to hook up two of the same devices to one board.
29 Any such information that is specific to an interface should be stored in a
30 private, driver-defined data structure and pointed to by eth->priv (see below).
31
32 So the call graph at this stage would look something like:
33 board_init()
34 eth_initialize()
35 board_eth_init() / cpu_eth_init()
36 driver_register()
37 initialize eth_device
38 eth_register()
39
2. 編寫功能代碼
接下來就需要根據網卡手冊進行配置，顯然，寫的都是裸板代碼，這里，我們的dm9000網卡的配置代碼如下，此為2.根據運行邏輯編寫相應的代碼。
31 struct exynos4_gpio_part2 *gpio2;
32 #ifdef CONFIG_DRIVER_DM9000
33 #define EXYNOS4412_SROMC_BASE 0X12570000
34 #define DM9000_Tacs (0x1)
35 #define DM9000_Tcos (0x1)
36 #define DM9000_Tacc (0x5)
37 #define DM9000_Tcoh (0x1)
38 #define DM9000_Tah (0xC)
39 #define DM9000_Tacp (0x9)
40 #define DM9000_PMC (0x1)
41 struct exynos_sromc {
42 unsigned int bw;
43 unsigned int bc[6];
44 };
45 /*
46 * s5p_config_sromc() - select the proper SROMC Bank and configure the
47 * band width control and bank control registers
48 * srom_bank - SROM
49 * srom_bw_conf - SMC Band witdh reg configuration value
50 * srom_bc_conf - SMC Bank Control reg configuration value
51 */
52 void exynos_config_sromc(u32 srom_bank, u32 srom_bw_conf, u32 srom_bc_conf)
53 {
54 unsigned int tmp;
55 struct exynos_sromc *srom = (struct exynos_sromc *)(EXYNOS4412_SROMC_BASE);
56 /* Configure SMC_BW register to handle proper SROMC bank */
57 tmp = srom->bw;
58 tmp&= ~(0xF << (srom_bank * 4));
59 tmp |= srom_bw_conf;
60 srom->bw = tmp;
61 /* Configure SMC_BC register */
62 srom->bc[srom_bank] = srom_bc_conf;
63 }
64 static void dm9000aep_pre_init(void)
65 {
66 unsigned int tmp;
67 unsigned char smc_bank_num = 1;
68 unsigned int
69 smc_bw_conf=0;
70 unsigned int
71 smc_bc_conf=0;
72 /* gpio configuration */
73 writel(0x00220020, 0x11000000 + 0x120);
74 writel(0x00002222, 0x11000000 + 0x140);
75 /* 16 Bit bus width */
76 writel(0x22222222, 0x11000000 + 0x180);
77 writel(0x0000FFFF, 0x11000000 + 0x188);
78 writel(0x22222222, 0x11000000 + 0x1C0);
79 writel(0x0000FFFF, 0x11000000 + 0x1C8);
80 writel(0x22222222, 0x11000000 + 0x1E0);
81 writel(0x0000FFFF, 0x11000000 + 0x1E8);
82 smc_bw_conf &= ~(0xf<<4);
83 smc_bw_conf |= (1<<7) | (1<<6) | (1<<5) | (1<<4);
84 smc_bc_conf = ((DM9000_Tacs << 28)
85 | (DM9000_Tcos << 24)
86 | (DM9000_Tacc << 16)
87 | (DM9000_Tcoh << 12)
88 | (DM9000_Tah << 8)
89 | (DM9000_Tacp << 4)
90 | (DM9000_PMC));
91 exynos_config_sromc(smc_bank_num,smc_bw_conf,smc_bc_conf);
92 }
93 #endif
94
95 int board_init(void)
100 gd->bd->bi_boot_params = (PHYS_SDRAM_1 + 0x100UL);
101 #ifdef CONFIG_DRIVER_DM9000
102 dm9000aep_pre_init();
103 #endif
104 return 0;
174 #endif
175 #ifdef CONFIG_CMD_NET
176 int board_eth_init(bd_t *bis)
177 {
178
179 int rc = 0;
180 #ifdef CONFIG_DRIVER_DM9000
181 rc = dm9000_initialize(bis);
182 #endif
183 return rc;
184 }
185 #endif
3. 找配置邏輯
將網卡代碼編寫好之后，我們來分析uboot的配置邏輯，這部分的大部分內容我已經在一文中進行了介紹，這里僅介紹和網卡相關的配置文件。和通用的配置文件一樣，我們首先需要將
在相關配置文件中添加網絡支持，一文中已經介紹了uboot的配置原理，make config最后生成的結果文件是"include/configs/xxx.h"，里面以宏的形式對板子的功能進行了配置，我們這里需要的文件是"include/configs/xboot.h"。
我們只需要打開或關閉相應的宏，就可以完成對某一功能的配置
4. 修改配置
我們主要的工作就是在頭文件中打開相應的宏開關，雖然不使用這種宏開關的方式也可以將功能添加成功，但是移植的一個重要原則就是尊重原架構，這對后期維護和代碼重用都很有好處。
85 #define CONFIG_CMD_PING //#undef CONFIG_CMD_PING
90 #define CONFIG_CMD_NET //#undef CONFIG_CMD_NET
155 /* Enable devicetree support */
156 #define CONFIG_OF_LIBFDT
157
158 #ifdef CONFIG_CMD_NET
159 #define CONFIG_NET_MULTI
160 #define CONFIG_DRIVER_DM9000 1
161 #define CONFIG_DM9000_BASE 0x05000000
162 #define DM9000_IO CONFIG_DM9000_BASE
163 #define DM9000_DATA (CONFIG_DM9000_BASE + 4)
164 #define CONFIG_DM9000_USE_16BIT
165 #define CONFIG_DM9000_NO_SROM 1
166 #define CONFIG_ETHADDR 11:22:33:44:55:66
167 #define CONFIG_IPADDR 192.168.9.200
168 #define CONFIG_SERVERIP 192.168.9.120
169 #define CONFIG_GATEWAYIP 192.168.9.1
170 #define CONFIG_NETMASK 255.255.255.0
171 #endif
172
173 #endif /* __CONFIG_H */
5. 重新編譯and燒寫
最終的結果如下, 我們可以看到dm9000已經啟動了
也可以正常的加載並啟動內核
