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- Calculate the I2C baud rate to keep them <100 kHz under different TCLK

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frequencies.  The maximum freqency is 100 kHz according to the datasheet.

- Add child device probing support based on the device tree.  It now tries to
  find i2c-address property in the tree and attach the device with given slave
  address to iicbus.
This commit is contained in:
Hiroki Sato 2012-08-21 17:49:20 +00:00
parent f8e8af9cf2
commit 8bfdf49b97
1 changed files with 122 additions and 13 deletions
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135
sys/arm/mv/twsi.c
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@ -47,6 +47,7 @@ __FBSDID("$FreeBSD$");
#include <sys/module.h>
#include <sys/resource.h>
#include <machine/_inttypes.h>
#include <machine/bus.h>
#include <machine/resource.h>
@ -57,12 +58,17 @@ __FBSDID("$FreeBSD$");
#include <dev/iicbus/iiconf.h>
#include <dev/iicbus/iicbus.h>
#include <dev/fdt/fdt_common.h>
#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>
#include <arm/mv/mvreg.h>
#include <arm/mv/mvvar.h>
#include "iicbus_if.h"
#define MV_TWSI_NAME "twsi"
#define IICBUS_DEVNAME "iicbus"
#define TWSI_SLAVE_ADDR 0x00
#define TWSI_EXT_SLAVE_ADDR 0x10
@ -86,10 +92,10 @@ __FBSDID("$FreeBSD$");
#define TWSI_STATUS_DATA_RD_NOACK 0x58
#define TWSI_BAUD_RATE 0x0c
#define TWSI_BAUD_RATE_94DOT3 0x53 /* N=3, M=10 */
#define TWSI_BAUD_RATE_74DOT1 0x6b /* N=3, M=13 */
#define TWSI_BAUD_RATE_51DOT8 0x4c /* N=4, M=9 */
#define TWSI_BAUD_RATE_99DOT7 0x66 /* N=6, M=12 */
#define TWSI_BAUD_RATE_PARAM(M,N) ((((M) << 3) | ((N) & 0x7)) & 0x7f)
#define TWSI_BAUD_RATE_RAW(C,M,N) ((C)/((10*(M+1))<<(N+1)))
#define TWSI_BAUD_RATE_SLOW 50000 /* 50kHz */
#define TWSI_BAUD_RATE_FAST 100000 /* 100kHz */
#define TWSI_SOFT_RESET 0x1c
@ -109,6 +115,13 @@ struct mv_twsi_softc {
device_t iicbus;
};
static struct mv_twsi_baud_rate {
uint32_t raw;
int param;
int m;
int n;
} baud_rate[IIC_FASTEST + 1];
static int mv_twsi_probe(device_t);
static int mv_twsi_attach(device_t);
static int mv_twsi_detach(device_t);
@ -299,13 +312,49 @@ mv_twsi_probe(device_t dev)
return (BUS_PROBE_DEFAULT);
}
#define ABSSUB(a,b) (((a) > (b)) ? (a) - (b) : (b) - (a))
static void
mv_twsi_cal_baud_rate(const uint32_t target, struct mv_twsi_baud_rate *rate)
{
uint32_t clk, cur, diff, diff0;
int m, n, m0, n0;
/* Calculate baud rate. */
m0 = n0 = 4; /* Default values on reset */
diff0 = 0xffffffff;
clk = get_tclk();
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;
}
}
}
rate->raw = TWSI_BAUD_RATE_RAW(clk, m0, n0);
rate->param = TWSI_BAUD_RATE_PARAM(m0, n0);
rate->m = m0;
rate->n = n0;
}
static int
mv_twsi_attach(device_t dev)
{
struct mv_twsi_softc *sc;
phandle_t child, iicbusnode;
device_t childdev;
struct iicbus_ivar *devi;
char dname[32]; /* 32 is taken from struct u_device */
uint32_t paddr;
int len, error;
sc = device_get_softc(dev);
sc->dev = dev;
bzero(baud_rate, sizeof(baud_rate));
mtx_init(&sc->mutex, device_get_nameunit(dev), MV_TWSI_NAME, MTX_DEF);
@ -316,14 +365,76 @@ mv_twsi_attach(device_t dev)
return (ENXIO);
}
sc->iicbus = device_add_child(dev, "iicbus", -1);
mv_twsi_cal_baud_rate(TWSI_BAUD_RATE_SLOW, &baud_rate[IIC_SLOW]);
mv_twsi_cal_baud_rate(TWSI_BAUD_RATE_FAST, &baud_rate[IIC_FAST]);
if (bootverbose)
device_printf(dev, "calculated baud rates are:\n"
" %" PRIu32 " kHz (M=%d, N=%d) for slow,\n"
" %" PRIu32 " kHz (M=%d, N=%d) for fast.\n",
baud_rate[IIC_SLOW].raw / 1000,
baud_rate[IIC_SLOW].m,
baud_rate[IIC_SLOW].n,
baud_rate[IIC_FAST].raw / 1000,
baud_rate[IIC_FAST].m,
baud_rate[IIC_FAST].n);
sc->iicbus = device_add_child(dev, IICBUS_DEVNAME, -1);
if (sc->iicbus == NULL) {
device_printf(dev, "could not add iicbus child\n");
mv_twsi_detach(dev);
return (ENXIO);
}
/* Attach iicbus. */
bus_generic_attach(dev);
iicbusnode = 0;
/* Find iicbus as the child devices in the device tree. */
for (child = OF_child(ofw_bus_get_node(dev)); child != 0;
child = OF_peer(child)) {
len = OF_getproplen(child, "model");
if (len <= 0 || len > sizeof(dname) - 1)
continue;
error = OF_getprop(child, "model", &dname, len);
dname[len + 1] = '\0';
if (error == -1)
continue;
len = strlen(dname);
if (len == strlen(IICBUS_DEVNAME) &&
strncasecmp(dname, IICBUS_DEVNAME, len) == 0) {
iicbusnode = child;
break;
}
}
if (iicbusnode == 0)
goto attach_end;
/* Attach child devices onto iicbus. */
for (child = OF_child(iicbusnode); child != 0; child = OF_peer(child)) {
/* Get slave address. */
error = OF_getprop(child, "i2c-address", &paddr, sizeof(paddr));
if (error == -1)
error = OF_getprop(child, "reg", &paddr, sizeof(paddr));
if (error == -1)
continue;
/* Get device driver name. */
len = OF_getproplen(child, "model");
if (len <= 0 || len > sizeof(dname) - 1)
continue;
OF_getprop(child, "model", &dname, len);
dname[len + 1] = '\0';
if (bootverbose)
device_printf(dev, "adding a device %s at %d.\n",
dname, fdt32_to_cpu(paddr));
childdev = BUS_ADD_CHILD(sc->iicbus, 0, dname, -1);
devi = IICBUS_IVAR(childdev);
devi->addr = fdt32_to_cpu(paddr);
}
attach_end:
bus_generic_attach(sc->iicbus);
return (0);
}
@ -355,28 +466,26 @@ static int
mv_twsi_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
{
struct mv_twsi_softc *sc;
uint32_t baud_rate;
uint32_t param;
sc = device_get_softc(dev);
switch (speed) {
case IIC_SLOW:
baud_rate = TWSI_BAUD_RATE_51DOT8;
break;
case IIC_FAST:
baud_rate = TWSI_BAUD_RATE_51DOT8;
param = baud_rate[speed].param;
break;
case IIC_UNKNOWN:
case IIC_FASTEST:
case IIC_UNKNOWN:
default:
baud_rate = TWSI_BAUD_RATE_99DOT7;
param = baud_rate[IIC_FAST].param;
break;
}
mtx_lock(&sc->mutex);
TWSI_WRITE(sc, TWSI_SOFT_RESET, 0x0);
DELAY(2000);
TWSI_WRITE(sc, TWSI_BAUD_RATE, baud_rate);
TWSI_WRITE(sc, TWSI_BAUD_RATE, param);
TWSI_WRITE(sc, TWSI_CONTROL, TWSI_CONTROL_TWSIEN | TWSI_CONTROL_ACK);
DELAY(1000);
mtx_unlock(&sc->mutex);