diff options
Diffstat (limited to 'drivers/memory')
| -rw-r--r-- | drivers/memory/omap-gpmc.c | 86 |
1 files changed, 79 insertions, 7 deletions
diff --git a/drivers/memory/omap-gpmc.c b/drivers/memory/omap-gpmc.c index 5c36ff3..768bab2 100644 --- a/drivers/memory/omap-gpmc.c +++ b/drivers/memory/omap-gpmc.c @@ -138,7 +138,9 @@ #define GPMC_CONFIG1_PAGE_LEN(val) ((val & 3) << 23) #define GPMC_CONFIG1_WAIT_READ_MON (1 << 22) #define GPMC_CONFIG1_WAIT_WRITE_MON (1 << 21) -#define GPMC_CONFIG1_WAIT_MON_IIME(val) ((val & 3) << 18) +#define GPMC_CONFIG1_WAIT_MON_TIME(val) ((val & 3) << 18) +/** WAITMONITORINGTIME Max Ticks */ +#define GPMC_CONFIG1_WAITMONITORINGTIME_MAX 2 #define GPMC_CONFIG1_WAIT_PIN_SEL(val) ((val & 3) << 16) #define GPMC_CONFIG1_DEVICESIZE(val) ((val & 3) << 12) #define GPMC_CONFIG1_DEVICESIZE_16 GPMC_CONFIG1_DEVICESIZE(1) @@ -525,13 +527,48 @@ static int set_gpmc_timing_reg(int cs, int reg, int st_bit, int end_bit, t->field, #field) < 0) \ return -1 +/** + * gpmc_calc_waitmonitoring_divider - calculate proper GPMCFCLKDIVIDER based on WAITMONITORINGTIME + * WAITMONITORINGTIME will be _at least_ as long as desired, i.e. + * read --> don't sample bus too early + * write --> data is longer on bus + * + * Formula: + * gpmc_clk_div + 1 = ceil(ceil(waitmonitoringtime_ns / gpmc_fclk_ns) + * / waitmonitoring_ticks) + * WAITMONITORINGTIME resulting in 0 or 1 tick with div = 1 are caught by + * div <= 0 check. + * + * @wait_monitoring: WAITMONITORINGTIME in ns. + * @return: -1 on failure to scale, else proper divider > 0. + */ +static int gpmc_calc_waitmonitoring_divider(unsigned int wait_monitoring) +{ + + int div = gpmc_ns_to_ticks(wait_monitoring); + + div += GPMC_CONFIG1_WAITMONITORINGTIME_MAX - 1; + div /= GPMC_CONFIG1_WAITMONITORINGTIME_MAX; + + if (div > 4) + return -1; + if (div <= 0) + div = 1; + + return div; + +} + +/** + * gpmc_calc_divider - calculate GPMC_FCLK divider for sync_clk GPMC_CLK period. + * @sync_clk: GPMC_CLK period in ps. + * @return: Returns at least 1 if GPMC_FCLK can be divided to GPMC_CLK. + * Else, returns -1. + */ int gpmc_calc_divider(unsigned int sync_clk) { - int div; - u32 l; + int div = gpmc_ps_to_ticks(sync_clk); - l = sync_clk + (gpmc_get_fclk_period() - 1); - div = l / gpmc_get_fclk_period(); if (div > 4) return -1; if (div <= 0) @@ -540,7 +577,15 @@ int gpmc_calc_divider(unsigned int sync_clk) return div; } -int gpmc_cs_set_timings(int cs, const struct gpmc_timings *t) +/** + * gpmc_cs_set_timings - program timing parameters for Chip Select Region. + * @cs: Chip Select Region. + * @t: GPMC timing parameters. + * @s: GPMC timing settings. + * @return: 0 on success, -1 on error. + */ +int gpmc_cs_set_timings(int cs, const struct gpmc_timings *t, + const struct gpmc_settings *s) { int div; u32 l; @@ -550,6 +595,33 @@ int gpmc_cs_set_timings(int cs, const struct gpmc_timings *t) if (div < 0) return div; + /* + * See if we need to change the divider for waitmonitoringtime. + * + * Calculate GPMCFCLKDIVIDER independent of gpmc,sync-clk-ps in DT for + * pure asynchronous accesses, i.e. both read and write asynchronous. + * However, only do so if WAITMONITORINGTIME is actually used, i.e. + * either WAITREADMONITORING or WAITWRITEMONITORING is set. + * + * This statement must not change div to scale async WAITMONITORINGTIME + * to protect mixed synchronous and asynchronous accesses. + * + * We raise an error later if WAITMONITORINGTIME does not fit. + */ + if (!s->sync_read && !s->sync_write && + (s->wait_on_read || s->wait_on_write) + ) { + + div = gpmc_calc_waitmonitoring_divider(t->wait_monitoring); + if (div < 0) { + pr_err("%s: waitmonitoringtime %3d ns too large for greatest gpmcfclkdivider.\n", + __func__, + t->wait_monitoring + ); + return -1; + } + } + GPMC_SET_ONE(GPMC_CS_CONFIG2, 0, 3, cs_on); GPMC_SET_ONE(GPMC_CS_CONFIG2, 8, 12, cs_rd_off); GPMC_SET_ONE(GPMC_CS_CONFIG2, 16, 20, cs_wr_off); @@ -1810,7 +1882,7 @@ static int gpmc_probe_generic_child(struct platform_device *pdev, if (ret < 0) goto err; - ret = gpmc_cs_set_timings(cs, &gpmc_t); + ret = gpmc_cs_set_timings(cs, &gpmc_t, &gpmc_s); if (ret) { dev_err(&pdev->dev, "failed to set gpmc timings for: %s\n", child->name); |
