From 8bfdf49b977c2623a06e5c915d6965451be2c7df Mon Sep 17 00:00:00 2001 From: Hiroki Sato Date: Tue, 21 Aug 2012 17:49:20 +0000 Subject: [PATCH] - Calculate the I2C baud rate to keep them <100 kHz under different TCLK 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. --- sys/arm/mv/twsi.c | 135 +++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 122 insertions(+), 13 deletions(-) diff --git a/sys/arm/mv/twsi.c b/sys/arm/mv/twsi.c index 2f8f76f5f3a3..7b284ae87c54 100644 --- a/sys/arm/mv/twsi.c +++ b/sys/arm/mv/twsi.c @@ -47,6 +47,7 @@ __FBSDID("$FreeBSD$"); #include #include +#include #include #include @@ -57,12 +58,17 @@ __FBSDID("$FreeBSD$"); #include #include +#include #include #include +#include +#include + #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);