diff options
| -rw-r--r-- | drivers/spi/spi-rzv2h-rspi.c | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/drivers/spi/spi-rzv2h-rspi.c b/drivers/spi/spi-rzv2h-rspi.c index da110efba971..1db7e4e5d64e 100644 --- a/drivers/spi/spi-rzv2h-rspi.c +++ b/drivers/spi/spi-rzv2h-rspi.c @@ -261,6 +261,105 @@ static inline u32 rzv2h_rspi_calc_bitrate(unsigned long tclk_rate, u8 spr, return DIV_ROUND_UP(tclk_rate, (2 * (spr + 1) * (1 << brdv))); } +static void rzv2h_rspi_find_rate_variable(struct clk *clk, u32 hz, + u8 spr_min, u8 spr_max, + struct rzv2h_rspi_best_clock *best) +{ + long clk_rate, clk_min_rate, clk_max_rate; + int min_rate_spr, max_rate_spr; + unsigned long error; + u32 actual_hz; + u8 brdv; + int spr; + + /* + * On T2H / N2H, the source for the SPI clock is PCLKSPIn, which is a + * 1/32, 1/30, 1/25 or 1/24 divider of PLL4, which is 2400MHz, + * resulting in either 75MHz, 80MHz, 96MHz or 100MHz. + */ + clk_min_rate = clk_round_rate(clk, 0); + if (clk_min_rate < 0) + return; + + clk_max_rate = clk_round_rate(clk, ULONG_MAX); + if (clk_max_rate < 0) + return; + + /* + * From the manual: + * Bit rate = f(PCLKSPIn) / (2 * (n + 1) * 2^N) + * + * If we adapt it to the current context, we get the following: + * hz = rate / ((spr + 1) * (1 << (brdv + 1))) + * + * This can be written in multiple forms depending on what we want to + * determine. + * + * To find the rate, having hz, spr and brdv: + * rate = hz * (spr + 1) * (1 << (brdv + 1) + * + * To find the spr, having rate, hz, and spr: + * spr = rate / (hz * (1 << (brdv + 1)) - 1 + */ + + for (brdv = RSPI_SPCMD_BRDV_MIN; brdv <= RSPI_SPCMD_BRDV_MAX; brdv++) { + /* Calculate the divisor needed to find the SPR from a rate. */ + u32 rate_div = hz * (1 << (brdv + 1)); + + /* + * If the SPR for the minimum rate is greater than the maximum + * allowed value skip this BRDV. The divisor increases with each + * BRDV iteration, so the following BRDV might result in a + * minimum SPR that is in the valid range. + */ + min_rate_spr = DIV_ROUND_CLOSEST(clk_min_rate, rate_div) - 1; + if (min_rate_spr > spr_max) + continue; + + /* + * If the SPR for the maximum rate is less than the minimum + * allowed value, exit. The divisor only increases with each + * BRDV iteration, so the following BRDV cannot result in a + * maximum SPR that is in the valid range. + */ + max_rate_spr = DIV_ROUND_CLOSEST(clk_max_rate, rate_div) - 1; + if (max_rate_spr < spr_min) + break; + + if (min_rate_spr < spr_min) + min_rate_spr = spr_min; + + if (max_rate_spr > spr_max) + max_rate_spr = spr_max; + + for (spr = min_rate_spr; spr <= max_rate_spr; spr++) { + clk_rate = (spr + 1) * rate_div; + + clk_rate = clk_round_rate(clk, clk_rate); + if (clk_rate <= 0) + continue; + + actual_hz = rzv2h_rspi_calc_bitrate(clk_rate, spr, brdv); + error = abs((long)hz - (long)actual_hz); + + if (error >= best->error) + continue; + + *best = (struct rzv2h_rspi_best_clock) { + .clk = clk, + .clk_rate = clk_rate, + .error = error, + .actual_hz = actual_hz, + .brdv = brdv, + .spr = spr, + }; + + if (!error) + return; + } + } +} + static void rzv2h_rspi_find_rate_fixed(struct clk *clk, u32 hz, u8 spr_min, u8 spr_max, struct rzv2h_rspi_best_clock *best) @@ -558,8 +657,17 @@ static const struct rzv2h_rspi_info rzv2h_info = { .num_clks = 3, }; +static const struct rzv2h_rspi_info rzt2h_info = { + .find_tclk_rate = rzv2h_rspi_find_rate_variable, + .find_pclk_rate = rzv2h_rspi_find_rate_fixed, + .tclk_name = "pclkspi", + .fifo_size = 4, + .num_clks = 2, +}; + static const struct of_device_id rzv2h_rspi_match[] = { { .compatible = "renesas,r9a09g057-rspi", &rzv2h_info }, + { .compatible = "renesas,r9a09g077-rspi", &rzt2h_info }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, rzv2h_rspi_match); |