diff options
Diffstat (limited to 'arch/powerpc/cpu/mpc85xx/ddr-gen3.c')
| -rw-r--r-- | arch/powerpc/cpu/mpc85xx/ddr-gen3.c | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/arch/powerpc/cpu/mpc85xx/ddr-gen3.c b/arch/powerpc/cpu/mpc85xx/ddr-gen3.c index 3e7a564..1be51d3 100644 --- a/arch/powerpc/cpu/mpc85xx/ddr-gen3.c +++ b/arch/powerpc/cpu/mpc85xx/ddr-gen3.c @@ -15,8 +15,18 @@ #error Invalid setting for CONFIG_CHIP_SELECTS_PER_CTRL #endif + +/* + * regs has the to-be-set values for DDR controller registers + * ctrl_num is the DDR controller number + * step: 0 goes through the initialization in one pass + * 1 sets registers and returns before enabling controller + * 2 resumes from step 1 and continues to initialize + * Dividing the initialization to two steps to deassert DDR reset signal + * to comply with JEDEC specs for RDIMMs. + */ void fsl_ddr_set_memctl_regs(const fsl_ddr_cfg_regs_t *regs, - unsigned int ctrl_num) + unsigned int ctrl_num, int step) { unsigned int i, bus_width; volatile ccsr_ddr_t *ddr; @@ -54,6 +64,9 @@ void fsl_ddr_set_memctl_regs(const fsl_ddr_cfg_regs_t *regs, return; } + if (step == 2) + goto step2; + if (regs->ddr_eor) out_be32(&ddr->eor, regs->ddr_eor); #ifdef CONFIG_SYS_FSL_ERRATUM_DDR111_DDR134 @@ -157,6 +170,20 @@ void fsl_ddr_set_memctl_regs(const fsl_ddr_cfg_regs_t *regs, out_be32(&ddr->debug[21], 0x24000000); #endif /* CONFIG_SYS_FSL_ERRATUM_DDR_A003474 */ + /* + * For RDIMMs, JEDEC spec requires clocks to be stable before reset is + * deasserted. Clocks start when any chip select is enabled and clock + * control register is set. Because all DDR components are connected to + * one reset signal, this needs to be done in two steps. Step 1 is to + * get the clocks started. Step 2 resumes after reset signal is + * deasserted. + */ + if (step == 1) { + udelay(200); + return; + } + +step2: /* Set, but do not enable the memory */ temp_sdram_cfg = regs->ddr_sdram_cfg; temp_sdram_cfg &= ~(SDRAM_CFG_MEM_EN); |