diff options
Diffstat (limited to 'cpu/mpc8xxx/ddr/lc_common_dimm_params.c')
| -rw-r--r-- | cpu/mpc8xxx/ddr/lc_common_dimm_params.c | 74 |
1 files changed, 69 insertions, 5 deletions
diff --git a/cpu/mpc8xxx/ddr/lc_common_dimm_params.c b/cpu/mpc8xxx/ddr/lc_common_dimm_params.c index fbeb236d95..e888e3ea56 100644 --- a/cpu/mpc8xxx/ddr/lc_common_dimm_params.c +++ b/cpu/mpc8xxx/ddr/lc_common_dimm_params.c @@ -11,6 +11,59 @@ #include "ddr.h" +unsigned int +compute_cas_latency_ddr3(const dimm_params_t *dimm_params, + common_timing_params_t *outpdimm, + unsigned int number_of_dimms) +{ + unsigned int i; + unsigned int tAAmin_ps = 0; + unsigned int tCKmin_X_ps = 0; + unsigned int common_caslat; + unsigned int caslat_actual; + unsigned int retry = 16; + unsigned int tmp; + const unsigned int mclk_ps = get_memory_clk_period_ps(); + + /* compute the common CAS latency supported between slots */ + tmp = dimm_params[0].caslat_X; + for (i = 1; i < number_of_dimms; i++) + tmp &= dimm_params[i].caslat_X; + common_caslat = tmp; + + /* compute the max tAAmin tCKmin between slots */ + for (i = 0; i < number_of_dimms; i++) { + tAAmin_ps = max(tAAmin_ps, dimm_params[i].tAA_ps); + tCKmin_X_ps = max(tCKmin_X_ps, dimm_params[i].tCKmin_X_ps); + } + /* validate if the memory clk is in the range of dimms */ + if (mclk_ps < tCKmin_X_ps) { + printf("The DIMM max tCKmin is %d ps," + "doesn't support the MCLK cycle %d ps\n", + tCKmin_X_ps, mclk_ps); + return 1; + } + /* determine the acutal cas latency */ + caslat_actual = (tAAmin_ps + mclk_ps - 1) / mclk_ps; + /* check if the dimms support the CAS latency */ + while (!(common_caslat & (1 << caslat_actual)) && retry > 0) { + caslat_actual++; + retry--; + } + /* once the caculation of caslat_actual is completed + * we must verify that this CAS latency value does not + * exceed tAAmax, which is 20 ns for all DDR3 speed grades + */ + if (caslat_actual * mclk_ps > 20000) { + printf("The choosen cas latency %d is too large\n", + caslat_actual); + return 1; + } + outpdimm->lowest_common_SPD_caslat = caslat_actual; + + return 0; +} + /* * compute_lowest_common_dimm_parameters() * @@ -46,12 +99,14 @@ compute_lowest_common_dimm_parameters(const dimm_params_t *dimm_params, unsigned int tQHS_ps = 0; unsigned int temp1, temp2; - unsigned int lowest_good_caslat; unsigned int additive_latency = 0; +#if !defined(CONFIG_FSL_DDR3) const unsigned int mclk_ps = get_memory_clk_period_ps(); + unsigned int lowest_good_caslat; unsigned int not_ok; debug("using mclk_ps = %u\n", mclk_ps); +#endif temp1 = 0; for (i = 0; i < number_of_dimms; i++) { @@ -164,6 +219,10 @@ compute_lowest_common_dimm_parameters(const dimm_params_t *dimm_params, "DIMMs detected!\n"); } +#if defined(CONFIG_FSL_DDR3) + if (compute_cas_latency_ddr3(dimm_params, outpdimm, number_of_dimms)) + return 1; +#else /* * Compute a CAS latency suitable for all DIMMs * @@ -281,6 +340,7 @@ compute_lowest_common_dimm_parameters(const dimm_params_t *dimm_params, } outpdimm->highest_common_derated_caslat = temp1; debug("highest common dereated CAS latency = %u\n", temp1); +#endif /* #if defined(CONFIG_FSL_DDR3) */ /* Determine if all DIMMs ECC capable. */ temp1 = 1; @@ -297,14 +357,14 @@ compute_lowest_common_dimm_parameters(const dimm_params_t *dimm_params, } outpdimm->all_DIMMs_ECC_capable = temp1; - +#ifndef CONFIG_FSL_DDR3 /* FIXME: move to somewhere else to validate. */ if (mclk_ps > tCKmax_max_ps) { printf("Warning: some of the installed DIMMs " "can not operate this slowly.\n"); return 1; } - +#endif /* * Compute additive latency. * @@ -314,7 +374,7 @@ compute_lowest_common_dimm_parameters(const dimm_params_t *dimm_params, * which comes from Trcd, and also note that: * add_lat + caslat must be >= 4 * - * For DDR3, FIXME additive latency determination + * For DDR3, we use the AL=0 * * When to use additive latency for DDR2: * @@ -371,7 +431,11 @@ compute_lowest_common_dimm_parameters(const dimm_params_t *dimm_params, } #elif defined(CONFIG_FSL_DDR3) -error "FIXME determine additive latency for DDR3" + /* + * The system will not use the global auto-precharge mode. + * However, it uses the page mode, so we set AL=0 + */ + additive_latency = 0; #endif /* |