Make this work a lot better:
Remove a lot of older cruft not needed. Improve ISR support, but it is still unused since polling is faster Properly initalize the speed register to get 90kb/s, not 400b/s. Try to catch NACK Allow 0 length read transfers to generate start/top pairs.
This commit is contained in:
Warner Losh
parent
fcf50d482e
commit
e8c8e11c08
@ -52,9 +52,7 @@ struct at91_twi_softc
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struct resource *irq_res; /* IRQ resource */
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struct resource *mem_res; /* Memory resource */
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struct mtx sc_mtx; /* basically a perimeter lock */
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volatile int flags;
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#define RXRDY 4
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#define TXRDY 0x10
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volatile uint32_t flags;
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uint32_t cwgr;
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int sc_started;
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int twi_addr;
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@ -131,8 +129,6 @@ at91_twi_attach(device_t dev)
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WR4(sc, TWI_CR, TWI_CR_SWRST);
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WR4(sc, TWI_CR, TWI_CR_MSEN | TWI_CR_SVDIS);
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WR4(sc, TWI_CWGR, sc->cwgr);
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// WR4(sc, TWI_IER, TWI_SR_RXRDY | TWI_SR_OVRE | TWI_SR_UNRE |
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// TWI_SR_NACK);
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if ((sc->iicbus = device_add_child(dev, "iicbus", -1)) == NULL)
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device_printf(dev, "could not allocate iicbus instance\n");
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@ -208,17 +204,17 @@ at91_twi_intr(void *xsc)
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struct at91_twi_softc *sc = xsc;
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uint32_t status;
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/* Reading the status also clears the interrupt */
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status = RD4(sc, TWI_SR);
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printf("status %x\n", status);
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if (status == 0)
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return;
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AT91_TWI_LOCK(sc);
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sc->flags |= status & (TWI_SR_OVRE | TWI_SR_UNRE | TWI_SR_NACK);
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if (status & TWI_SR_RXRDY)
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sc->flags |= RXRDY;
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sc->flags |= TWI_SR_RXRDY;
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if (status & TWI_SR_TXRDY)
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sc->flags |= TXRDY;
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AT91_TWI_UNLOCK(sc);
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sc->flags |= TWI_SR_TXRDY;
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if (status & TWI_SR_TXCOMP)
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sc->flags |= TWI_SR_TXCOMP;
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WR4(sc, TWI_IDR, status);
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wakeup(sc);
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return;
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}
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@ -228,11 +224,16 @@ at91_twi_wait(struct at91_twi_softc *sc, uint32_t bit)
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{
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int err = 0;
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int counter = 100000;
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uint32_t sr;
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while (!(RD4(sc, TWI_SR) & bit) && counter-- >= 0)
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while (!((sr = RD4(sc, TWI_SR)) & bit) && counter-- > 0)
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continue;
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if (counter <= 0)
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err = EIO;
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err = EBUSY;
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else if (sr & TWI_SR_NACK)
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err = EADDRNOTAVAIL;
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if (sr & ~bit)
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printf("status is %x\n", sr);
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return (err);
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}
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@ -240,42 +241,37 @@ static int
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at91_twi_rst_card(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
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{
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struct at91_twi_softc *sc;
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int ckdiv, rate;
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int clk;
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sc = device_get_softc(dev);
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if (oldaddr)
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*oldaddr = sc->twi_addr;
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if (addr != 0)
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sc->twi_addr = 0;
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else
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sc->twi_addr = addr;
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sc->twi_addr = addr;
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rate = 1;
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/*
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* speeds are for 1.5kb/s, 45kb/s and 90kb/s.
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*/
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switch (speed) {
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case IIC_SLOW:
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ckdiv = AT91C_MASTER_CLOCK / (1500 * 4) - 2;
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clk = 1500;
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break;
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case IIC_FAST:
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ckdiv = AT91C_MASTER_CLOCK / (45000 * 4) - 2;
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clk = 45000;
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break;
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case IIC_UNKNOWN:
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case IIC_FASTEST:
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default:
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ckdiv = AT91C_MASTER_CLOCK / (90000 * 4) - 2;
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clk = 90000;
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break;
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}
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sc->cwgr = TWI_CWGR_CKDIV(ckdiv) | TWI_CWGR_CHDIV(TWI_CWGR_DIV(rate)) |
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TWI_CWGR_CLDIV(TWI_CWGR_DIV(rate));
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sc->cwgr = TWI_CWGR_CKDIV(1) | TWI_CWGR_CHDIV(TWI_CWGR_DIV(clk)) |
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TWI_CWGR_CLDIV(TWI_CWGR_DIV(clk));
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WR4(sc, TWI_CR, TWI_CR_SWRST);
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WR4(sc, TWI_CR, TWI_CR_MSEN | TWI_CR_SVDIS);
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WR4(sc, TWI_CWGR, sc->cwgr);
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printf("setting cwgr to %#x\n", sc->cwgr);
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return 0;
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}
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@ -303,32 +299,36 @@ static int
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at91_twi_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
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{
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struct at91_twi_softc *sc;
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int i, len;
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int i, len, err;
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uint32_t rdwr;
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uint8_t *buf;
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sc = device_get_softc(dev);
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err = 0;
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AT91_TWI_LOCK(sc);
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for (i = 0; i < nmsgs; i++) {
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/*
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* The linux atmel driver doesn't use the internal device
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* address feature of twi. A separate i2c message needs to
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* be written to use this.
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* See http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2004-September/024411.html
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* for details.
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* for details. Upon reflection, we could use this as an
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* optimization, but it is unclear the code bloat will
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* result in faster/better operations.
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*/
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rdwr = (msgs[i].flags & IIC_M_RD) ? TWI_MMR_MREAD : 0;
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WR4(sc, TWI_MMR, TWI_MMR_DADR(msgs[i].slave) | rdwr);
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len = msgs[i].len;
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buf = msgs[i].buf;
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if (len == 0 || buf == NULL)
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if (len != 0 && buf == NULL)
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return (EINVAL);
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WR4(sc, TWI_CR, TWI_CR_START);
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if (msgs[i].flags & IIC_M_RD) {
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while (len--) {
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if (len == 0)
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WR4(sc, TWI_CR, TWI_CR_STOP);
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if (at91_twi_wait(sc, TWI_SR_RXRDY))
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return (EIO);
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if ((err = at91_twi_wait(sc, TWI_SR_RXRDY)))
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goto out;
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*buf++ = RD4(sc, TWI_RHR) & 0xff;
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}
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} else {
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@ -336,14 +336,22 @@ at91_twi_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
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WR4(sc, TWI_THR, *buf++);
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if (len == 0)
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WR4(sc, TWI_CR, TWI_CR_STOP);
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if (at91_twi_wait(sc, TWI_SR_TXRDY))
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return (EIO);
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if ((err = at91_twi_wait(sc, TWI_SR_TXRDY))) {
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printf("Len %d\n", len);
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goto out;
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}
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}
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}
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if (at91_twi_wait(sc, TWI_SR_TXCOMP))
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return (EIO);
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if ((err = at91_twi_wait(sc, TWI_SR_TXCOMP)))
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break;
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}
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return (0);
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out:;
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if (err) {
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WR4(sc, TWI_CR, TWI_CR_STOP);
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printf("Err is %d\n", err);
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}
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AT91_TWI_UNLOCK(sc);
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return (err);
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}
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static device_method_t at91_twi_methods[] = {
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