From 2eec998d6ed491e0fb3872d9798a007eaadee4a1 Mon Sep 17 00:00:00 2001 From: Phil Elwell Date: Tue, 16 Jan 2024 15:54:22 +0000 Subject: [PATCH] i2c: designware: Use SCL rise and fall times in DT Calculate the HCNT and LCNT values for all modes using the rise and fall times of SCL, the aim being a 50/50 mark/space ratio. Signed-off-by: Phil Elwell --- drivers/i2c/busses/i2c-designware-master.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c index ee04634..50604b6 100644 --- a/drivers/i2c/busses/i2c-designware-master.c +++ b/drivers/i2c/busses/i2c-designware-master.c @@ -38,6 +38,22 @@ static void i2c_dw_configure_fifo_master(struct dw_i2c_dev *dev) regmap_write(dev->map, DW_IC_CON, dev->master_cfg); } +static u16 clock_calc(struct dw_i2c_dev *dev, bool want_high) +{ + struct i2c_timings *t = &dev->timings; + u32 wanted_speed = t->bus_freq_hz; + u32 clk_khz = i2c_dw_clk_rate(dev); + u32 extra_ns = want_high ? t->scl_fall_ns : t->scl_rise_ns; + u32 extra_cycles = (u32)((u64)clk_khz * extra_ns / 1000000); + u32 period = ((u64)clk_khz * 1000 + wanted_speed - 1) / wanted_speed; + u32 cycles = (period + want_high)/2 - extra_cycles; + + if (cycles > 0xffff) + cycles = 0xffff; + + return (u16)cycles; +} + static int i2c_dw_set_timings_master(struct dw_i2c_dev *dev) { unsigned int comp_param1; @@ -45,6 +61,7 @@ static int i2c_dw_set_timings_master(struct dw_i2c_dev *dev) struct i2c_timings *t = &dev->timings; const char *fp_str = ""; u32 ic_clk; + u32 hcnt, lcnt; int ret; ret = i2c_dw_acquire_lock(dev); @@ -60,6 +77,9 @@ static int i2c_dw_set_timings_master(struct dw_i2c_dev *dev) sda_falling_time = t->sda_fall_ns ?: 300; /* ns */ scl_falling_time = t->scl_fall_ns ?: 300; /* ns */ + hcnt = clock_calc(dev, true); + lcnt = clock_calc(dev, false); + /* Calculate SCL timing parameters for standard mode if not set */ if (!dev->ss_hcnt || !dev->ss_lcnt) { ic_clk = i2c_dw_clk_rate(dev); @@ -75,6 +95,8 @@ static int i2c_dw_set_timings_master(struct dw_i2c_dev *dev) scl_falling_time, 0); /* No offset */ } + dev->ss_hcnt = hcnt; + dev->ss_lcnt = lcnt; dev_dbg(dev->dev, "Standard Mode HCNT:LCNT = %d:%d\n", dev->ss_hcnt, dev->ss_lcnt); @@ -125,6 +147,8 @@ static int i2c_dw_set_timings_master(struct dw_i2c_dev *dev) scl_falling_time, 0); /* No offset */ } + dev->fs_hcnt = hcnt; + dev->fs_lcnt = lcnt; dev_dbg(dev->dev, "Fast Mode%s HCNT:LCNT = %d:%d\n", fp_str, dev->fs_hcnt, dev->fs_lcnt); @@ -153,6 +177,8 @@ static int i2c_dw_set_timings_master(struct dw_i2c_dev *dev) scl_falling_time, 0); /* No offset */ } + dev->hs_hcnt = hcnt; + dev->hs_lcnt = lcnt; dev_dbg(dev->dev, "High Speed Mode HCNT:LCNT = %d:%d\n", dev->hs_hcnt, dev->hs_lcnt); } -- 2.7.4