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twsi: Calculate the clock param based on the bus frequency

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Instead of precalculating the different speed, respect the bus frequency
and calculate the clock register parameter based on it.
If the platform didn't register the core clk, fallback on the precomputed
values (This is likely do be the case on Marvell boards).
This commit is contained in:
Emmanuel Vadot 2019-05-11 15:03:51 +00:00
parent e69181cfc6
commit f78a4afd30
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=347491
2 changed files with 65 additions and 42 deletions
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31
sys/dev/iicbus/twsi/a10_twsi.c
View File

@ -87,9 +87,7 @@ static int
a10_twsi_attach(device_t dev)
{
struct twsi_softc *sc;
clk_t clk;
hwreset_t rst;
uint64_t freq;
int error;
sc = device_get_softc(dev);
@ -104,12 +102,12 @@ a10_twsi_attach(device_t dev)
}
/* Activate clock */
error = clk_get_by_ofw_index(dev, 0, 0, &clk);
error = clk_get_by_ofw_index(dev, 0, 0, &sc->clk_core);
if (error != 0) {
device_printf(dev, "could not find clock\n");
return (error);
}
error = clk_enable(clk);
error = clk_enable(sc->clk_core);
if (error != 0) {
device_printf(dev, "could not enable clock\n");
return (error);
@ -123,31 +121,6 @@ a10_twsi_attach(device_t dev)
sc->reg_baud_rate = TWI_CCR;
sc->reg_soft_reset = TWI_SRST;
/* Setup baud rate params */
clk_get_freq(clk, &freq);
switch (freq) {
/*
* Formula is
* F0 = FINT / 2 ^ CLK_N
* F1 = F0 / (CLK_M + 1)
*
* Doc says that the output freq is F1/10 but my logic analyzer says otherwise
*/
case 48000000:
sc->baud_rate[IIC_SLOW].param = TWSI_BAUD_RATE_PARAM(11, 1);
sc->baud_rate[IIC_FAST].param = TWSI_BAUD_RATE_PARAM(11, 1);
sc->baud_rate[IIC_FASTEST].param = TWSI_BAUD_RATE_PARAM(2, 1);
break;
case 24000000:
sc->baud_rate[IIC_SLOW].param = TWSI_BAUD_RATE_PARAM(5, 2);
sc->baud_rate[IIC_FAST].param = TWSI_BAUD_RATE_PARAM(5, 2);
sc->baud_rate[IIC_FASTEST].param = TWSI_BAUD_RATE_PARAM(2, 2);
break;
default:
device_printf(dev, "Non supported frequency\n");
return (ENXIO);
}
sc->need_ack = true;
return (twsi_attach(dev));
}

76
sys/dev/iicbus/twsi/twsi.c
View File

@ -243,6 +243,43 @@ twsi_locked_start(device_t dev, struct twsi_softc *sc, int32_t mask,
return (IIC_NOERR);
}
#ifdef EXT_RESOURCES
#define TWSI_BAUD_RATE_RAW(C,M,N) ((C)/((10*(M+1))<<(N)))
#define ABSSUB(a,b) (((a) > (b)) ? (a) - (b) : (b) - (a))
static int
twsi_calc_baud_rate(struct twsi_softc *sc, const u_int target,
int *param)
{
uint64_t clk;
uint32_t cur, diff, diff0;
int m, n, m0, n0;
/* Calculate baud rate. */
diff0 = 0xffffffff;
if (clk_get_freq(sc->clk_core, &clk) < 0)
return (-1);
debugf(sc->dev, "Bus clock is at %lu\n", clk);
for (n = 0; n < 8; n++) {
for (m = 0; m < 16; m++) {
cur = TWSI_BAUD_RATE_RAW(clk,m,n);
diff = ABSSUB(target, cur);
if (diff < diff0) {
m0 = m;
n0 = n;
diff0 = diff;
}
}
}
*param = TWSI_BAUD_RATE_PARAM(m0, n0);
return (0);
}
#endif /* EXT_RESOURCES */
/*
* Only slave mode supported, disregard [old]addr
*/
@ -251,23 +288,35 @@ twsi_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
{
struct twsi_softc *sc;
uint32_t param;
/* uint32_t val; */
#ifdef EXT_RESOURCES
u_int busfreq;
#endif
sc = device_get_softc(dev);
switch (speed) {
case IIC_SLOW:
case IIC_FAST:
param = sc->baud_rate[speed].param;
debugf(dev, "Using IIC_FAST mode with speed param=%x\n", param);
break;
case IIC_FASTEST:
case IIC_UNKNOWN:
default:
param = sc->baud_rate[IIC_FAST].param;
debugf(dev, "Using IIC_FASTEST/UNKNOWN mode with speed param=%x\n", param);
break;
#ifdef EXT_RESOURCES
busfreq = IICBUS_GET_FREQUENCY(sc->iicbus, speed);
if (twsi_calc_baud_rate(sc, busfreq, &param) == -1) {
#endif
switch (speed) {
case IIC_SLOW:
case IIC_FAST:
param = sc->baud_rate[speed].param;
debugf(dev, "Using IIC_FAST mode with speed param=%x\n", param);
break;
case IIC_FASTEST:
case IIC_UNKNOWN:
default:
param = sc->baud_rate[IIC_FAST].param;
debugf(dev, "Using IIC_FASTEST/UNKNOWN mode with speed param=%x\n", param);
break;
}
#ifdef EXT_RESOURCES
}
#endif
debugf(dev, "Using clock param=%x\n", param);
mtx_lock(&sc->mutex);
TWSI_WRITE(sc, sc->reg_soft_reset, 0x0);
@ -521,6 +570,7 @@ twsi_intr(void *arg)
break;
case TWSI_STATUS_ADDR_R_ACK:
debugf(sc->dev, "Ack received after transmitting the address\n");
sc->recv_bytes = 0;
TWSI_WRITE(sc, sc->reg_control, sc->control_val);