projects / J-u-boot.git / blame
| Commit | Line | Data |
|---|---|---|
| c5c1af21 CLS |
1 | |
| 2 | -------------------------------------------- | |
| 3 | SOCFPGA Documentation for U-Boot and SPL | |
| 4 | -------------------------------------------- | |
| 5 | ||
| 6 | This README is about U-Boot and SPL support for Altera's ARM Cortex-A9MPCore | |
| 7 | based SOCFPGA. To know more about the hardware itself, please refer to | |
| 8 | www.altera.com. | |
| 9 | ||
| 10 | ||
| 11 | -------------------------------------------- | |
| 12 | socfpga_dw_mmc | |
| 13 | -------------------------------------------- | |
| 14 | Here are macro and detailed configuration required to enable DesignWare SDMMC | |
| 15 | controller support within SOCFPGA | |
| 16 | ||
| 17 | #define CONFIG_MMC | |
| 18 | -> To enable the SD MMC framework support | |
| 19 | ||
| 20 | #define CONFIG_SDMMC_BASE (SOCFPGA_SDMMC_ADDRESS) | |
| 21 | -> The base address of CSR register for DesignWare SDMMC controller | |
| 22 | ||
| 23 | #define CONFIG_GENERIC_MMC | |
| 24 | -> Enable the generic MMC driver | |
| 25 | ||
| 26 | #define CONFIG_SYS_MMC_MAX_BLK_COUNT 256 | |
| 27 | -> Using smaller max blk cnt to avoid flooding the limited stack in OCRAM | |
| 28 | ||
| 29 | #define CONFIG_DWMMC | |
| 30 | -> Enable the common DesignWare SDMMC controller framework | |
| 31 | ||
| 32 | #define CONFIG_SOCFPGA_DWMMC | |
| 33 | -> Enable the SOCFPGA specific driver for DesignWare SDMMC controller | |
| 34 | ||
| 35 | #define CONFIG_SOCFPGA_DWMMC_FIFO_DEPTH 1024 | |
| 36 | -> The FIFO depth for SOCFPGA DesignWare SDMMC controller | |
| 37 | ||
| 38 | #define CONFIG_SOCFPGA_DWMMC_DRVSEL 3 | |
| 39 | -> Phase-shifted clock of sdmmc_clk for controller to drive command and data to | |
| 40 | the card to meet hold time requirements. SD clock is running at 50MHz and | |
| 41 | drvsel is set to shift 135 degrees (3 * 45 degrees). With that, the hold time | |
| 42 | is 135 / 360 * 20ns = 7.5ns. | |
| 43 | ||
| 44 | #define CONFIG_SOCFPGA_DWMMC_SMPSEL 0 | |
| 45 | -> Phase-shifted clock of sdmmc_clk used to sample the command and data from | |
| 46 | the card | |
| 47 | ||
| 48 | #define CONFIG_SOCFPGA_DWMMC_BUS_WIDTH 4 | |
| 49 | -> Bus width of data line which either 1, 4 or 8 and based on board routing. | |
| 50 | ||
| 51 | #define CONFIG_SOCFPGA_DWMMC_BUS_HZ 50000000 | |
| 52 | -> The clock rate to controller. Do note the controller have a wrapper which | |
| 53 | divide the clock from PLL by 4. |