static int riic_init_hw(struct riic_dev *riic, u32 spd)
{
int ret;
unsigned long rate;
ret = clk_prepare_enable(riic->clk);
if (ret)
return ret;
/*
* TODO: Implement formula to calculate the timing values depending on
* variable parent clock rate and arbitrary bus speed
*/
rate = clk_get_rate(riic->clk);
if (rate != 33325000) {
dev_err(&riic->adapter.dev,
"invalid parent clk (%lu). Must be 33325000Hz\n", rate);
clk_disable_unprepare(riic->clk);
return -EINVAL;
}
/* Changing the order of accessing IICRST and ICE may break things! */
writeb(ICCR1_IICRST | ICCR1_SOWP, riic->base + RIIC_ICCR1);
riic_clear_set_bit(riic, 0, ICCR1_ICE, RIIC_ICCR1);
switch (spd) {
case 100000:
writeb(ICMR1_CKS(3), riic->base + RIIC_ICMR1);
writeb(ICBRH_SP100K, riic->base + RIIC_ICBRH);
writeb(ICBRL_SP100K, riic->base + RIIC_ICBRL);
break;
case 400000:
writeb(ICMR1_CKS(1), riic->base + RIIC_ICMR1);
writeb(ICBRH_SP400K, riic->base + RIIC_ICBRH);
writeb(ICBRL_SP400K, riic->base + RIIC_ICBRL);
break;
default:
dev_err(&riic->adapter.dev,
"unsupported bus speed (%dHz). Use 100000 or 400000\n", spd);
clk_disable_unprepare(riic->clk);
return -EINVAL;
}
writeb(0, riic->base + RIIC_ICSER);
writeb(ICMR3_ACKWP | ICMR3_RDRFS, riic->base + RIIC_ICMR3);
riic_clear_set_bit(riic, ICCR1_IICRST, 0, RIIC_ICCR1);
clk_disable_unprepare(riic->clk);
return 0;
}
static int riic_init_hw(struct riic_dev *riic, struct i2c_timings *t)
{
int ret = 0;
unsigned long rate;
int total_ticks, cks, brl, brh;
pm_runtime_get_sync(riic->adapter.dev.parent);
if (t->bus_freq_hz > 400000) {
dev_err(&riic->adapter.dev,
"unsupported bus speed (%dHz). 400000 max\n",
t->bus_freq_hz);
ret = -EINVAL;
goto out;
}
rate = clk_get_rate(riic->clk);
/*
* Assume the default register settings:
* FER.SCLE = 1 (SCL sync circuit enabled, adds 2 or 3 cycles)
* FER.NFE = 1 (noise circuit enabled)
* MR3.NF = 0 (1 cycle of noise filtered out)
*
* Freq (CKS=000) = (I2CCLK + tr + tf)/ (BRH + 3 + 1) + (BRL + 3 + 1)
* Freq (CKS!=000) = (I2CCLK + tr + tf)/ (BRH + 2 + 1) + (BRL + 2 + 1)
*/
/*
* Determine reference clock rate. We must be able to get the desired
* frequency with only 62 clock ticks max (31 high, 31 low).
* Aim for a duty of 60% LOW, 40% HIGH.
*/
total_ticks = DIV_ROUND_UP(rate, t->bus_freq_hz);
for (cks = 0; cks < 7; cks++) {
/*
* 60% low time must be less than BRL + 2 + 1
* BRL max register value is 0x1F.
*/
brl = ((total_ticks * 6) / 10);
if (brl <= (0x1F + 3))
break;
total_ticks /= 2;
rate /= 2;
}
if (brl > (0x1F + 3)) {
dev_err(&riic->adapter.dev, "invalid speed (%lu). Too slow.\n",
(unsigned long)t->bus_freq_hz);
ret = -EINVAL;
goto out;
}
brh = total_ticks - brl;
/* Remove automatic clock ticks for sync circuit and NF */
if (cks == 0) {
brl -= 4;
brh -= 4;
} else {
brl -= 3;
brh -= 3;
}
/*
* Remove clock ticks for rise and fall times. Convert ns to clock
* ticks.
*/
brl -= t->scl_fall_ns / (1000000000 / rate);
brh -= t->scl_rise_ns / (1000000000 / rate);
/* Adjust for min register values for when SCLE=1 and NFE=1 */
if (brl < 1)
brl = 1;
if (brh < 1)
brh = 1;
pr_debug("i2c-riic: freq=%lu, duty=%d, fall=%lu, rise=%lu, cks=%d, brl=%d, brh=%d\n",
rate / total_ticks, ((brl + 3) * 100) / (brl + brh + 6),
t->scl_fall_ns / (1000000000 / rate),
t->scl_rise_ns / (1000000000 / rate), cks, brl, brh);
/* Changing the order of accessing IICRST and ICE may break things! */
writeb(ICCR1_IICRST | ICCR1_SOWP, riic->base + RIIC_ICCR1);
riic_clear_set_bit(riic, 0, ICCR1_ICE, RIIC_ICCR1);
writeb(ICMR1_CKS(cks), riic->base + RIIC_ICMR1);
writeb(brh | ICBR_RESERVED, riic->base + RIIC_ICBRH);
writeb(brl | ICBR_RESERVED, riic->base + RIIC_ICBRL);
writeb(0, riic->base + RIIC_ICSER);
writeb(ICMR3_ACKWP | ICMR3_RDRFS, riic->base + RIIC_ICMR3);
riic_clear_set_bit(riic, ICCR1_IICRST, 0, RIIC_ICCR1);
out:
pm_runtime_put(riic->adapter.dev.parent);
return ret;
}
