FreeBSD/Linux Kernel Cross Reference
sys/arm/ti/ti_i2c.c

     /*-
      * Copyright (c) 2011
      *      Ben Gray <ben.r.gray@gmail.com>.
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    /**
     * Driver for the I2C module on the TI SoC.
     *
     * This driver is heavily based on the TWI driver for the AT91 (at91_twi.c).
     *
     * CAUTION: The I2Ci registers are limited to 16 bit and 8 bit data accesses,
     * 32 bit data access is not allowed and can corrupt register content.
     *
     * This driver currently doesn't use DMA for the transfer, although I hope to
     * incorporate that sometime in the future.  The idea being that for transaction
     * larger than a certain size the DMA engine is used, for anything less the
     * normal interrupt/fifo driven option is used.
     *
     *
     * WARNING: This driver uses mtx_sleep and interrupts to perform transactions,
     * which means you can't do a transaction during startup before the interrupts
     * have been enabled.  Hint - the freebsd function config_intrhook_establish().
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/10.0/sys/arm/ti/ti_i2c.c 239281 2012-08-15 06:31:32Z gonzo $");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/bus.h>
    #include <sys/conf.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/mbuf.h>
    #include <sys/malloc.h>
    #include <sys/module.h>
    #include <sys/mutex.h>
    #include <sys/rman.h>
    #include <machine/bus.h>
    
    #include <dev/fdt/fdt_common.h>
    #include <dev/ofw/openfirm.h>
    #include <dev/ofw/ofw_bus.h>
    #include <dev/ofw/ofw_bus_subr.h>
    
    #include <arm/ti/ti_prcm.h>
    #include <arm/ti/ti_i2c.h>
    
    #include <dev/iicbus/iiconf.h>
    #include <dev/iicbus/iicbus.h>
    
    #include "iicbus_if.h"
    
    /**
     *      I2C device driver context, a pointer to this is stored in the device
     *      driver structure.
     */
    struct ti_i2c_softc
    {
            device_t                sc_dev;
            uint32_t                device_id;
            struct resource*        sc_irq_res;
            struct resource*        sc_mem_res;
            device_t                sc_iicbus;
    
            void*                   sc_irq_h;
    
            struct mtx              sc_mtx;
    
            volatile uint16_t       sc_stat_flags;  /* contains the status flags last IRQ */
    
            uint16_t                sc_i2c_addr;
            uint16_t                sc_rev;
    };
    
    struct ti_i2c_clock_config
    {
           int speed;
           int bitrate;
           uint8_t psc;            /* Fast/Standard mode prescale divider */
           uint8_t scll;           /* Fast/Standard mode SCL low time */
           uint8_t sclh;           /* Fast/Standard mode SCL high time */
           uint8_t hsscll;         /* High Speed mode SCL low time */
           uint8_t hssclh;         /* High Speed mode SCL high time */
   };
   
   static struct ti_i2c_clock_config ti_i2c_clock_configs[] = {
   
   #if defined(SOC_OMAP4)
           { IIC_SLOW,      100000, 23,  13,  15, 0,  0},
           { IIC_FAST,      400000,  9,   5,   7, 0,  0},
           { IIC_FASTEST,  3310000,  1, 113, 115, 7, 10},
   #elif defined(SOC_TI_AM335X)
           { IIC_SLOW,      100000,  3,  53,  55, 0,  0},
           { IIC_FAST,      400000,  3,   8,  10, 0,  0},
           { IIC_FASTEST,   400000,  3,   8,  10, 0,  0}, /* This might be higher */
   #else
   #error "TI I2C driver is not supported on this SoC"
   #endif
           { -1, 0 }
   };
   
   
   #define TI_I2C_REV1  0x003C      /* OMAP3 */
   #define TI_I2C_REV2  0x000A      /* OMAP4 */
   
   /**
    *      Locking macros used throughout the driver
    */
   #define TI_I2C_LOCK(_sc)             mtx_lock(&(_sc)->sc_mtx)
   #define TI_I2C_UNLOCK(_sc)           mtx_unlock(&(_sc)->sc_mtx)
   #define TI_I2C_LOCK_INIT(_sc) \
           mtx_init(&_sc->sc_mtx, device_get_nameunit(_sc->sc_dev), \
                    "ti_i2c", MTX_DEF)
   #define TI_I2C_LOCK_DESTROY(_sc)      mtx_destroy(&_sc->sc_mtx);
   #define TI_I2C_ASSERT_LOCKED(_sc)     mtx_assert(&_sc->sc_mtx, MA_OWNED);
   #define TI_I2C_ASSERT_UNLOCKED(_sc)   mtx_assert(&_sc->sc_mtx, MA_NOTOWNED);
   
   #ifdef DEBUG
   #define ti_i2c_dbg(_sc, fmt, args...) \
       device_printf((_sc)->sc_dev, fmt, ##args)
   #else
   #define ti_i2c_dbg(_sc, fmt, args...)
   #endif
   
   static devclass_t ti_i2c_devclass;
   
   /* bus entry points */
   
   static int ti_i2c_probe(device_t dev);
   static int ti_i2c_attach(device_t dev);
   static int ti_i2c_detach(device_t dev);
   static void ti_i2c_intr(void *);
   
   /* OFW routine */
   static phandle_t ti_i2c_get_node(device_t bus, device_t dev);
   
   /* helper routines */
   static int ti_i2c_activate(device_t dev);
   static void ti_i2c_deactivate(device_t dev);
   
   /**
    *      ti_i2c_read_2 - reads a 16-bit value from one of the I2C registers
    *      @sc: I2C device context
    *      @off: the byte offset within the register bank to read from.
    *
    *
    *      LOCKING:
    *      No locking required
    *
    *      RETURNS:
    *      16-bit value read from the register.
    */
   static inline uint16_t
   ti_i2c_read_2(struct ti_i2c_softc *sc, bus_size_t off)
   {
           return bus_read_2(sc->sc_mem_res, off);
   }
   
   /**
    *      ti_i2c_write_2 - writes a 16-bit value to one of the I2C registers
    *      @sc: I2C device context
    *      @off: the byte offset within the register bank to read from.
    *      @val: the value to write into the register
    *
    *      LOCKING:
    *      No locking required
    *
    *      RETURNS:
    *      16-bit value read from the register.
    */
   static inline void
   ti_i2c_write_2(struct ti_i2c_softc *sc, bus_size_t off, uint16_t val)
   {
           bus_write_2(sc->sc_mem_res, off, val);
   }
   
   /**
    *      ti_i2c_read_reg - reads a 16-bit value from one of the I2C registers
    *          take into account revision-dependent register offset
    *      @sc: I2C device context
    *      @off: the byte offset within the register bank to read from.
    *
    *
    *      LOCKING:
    *      No locking required
    *
    *      RETURNS:
    *      16-bit value read from the register.
    */
   static inline uint16_t
   ti_i2c_read_reg(struct ti_i2c_softc *sc, bus_size_t off)
   {
           /* XXXOMAP3: FIXME add registers mapping here */
           return bus_read_2(sc->sc_mem_res, off);
   }
   
   /**
    *      ti_i2c_write_reg - writes a 16-bit value to one of the I2C registers
    *          take into account revision-dependent register offset
    *      @sc: I2C device context
    *      @off: the byte offset within the register bank to read from.
    *      @val: the value to write into the register
    *
    *      LOCKING:
    *      No locking required
    *
    *      RETURNS:
    *      16-bit value read from the register.
    */
   static inline void
   ti_i2c_write_reg(struct ti_i2c_softc *sc, bus_size_t off, uint16_t val)
   {
           /* XXXOMAP3: FIXME add registers mapping here */
           bus_write_2(sc->sc_mem_res, off, val);
   }
   
   /**
    *      ti_i2c_set_intr_enable - writes the interrupt enable register
    *      @sc: I2C device context
    *      @ie: bitmask of the interrupts to enable
    *
    *      This function is needed as writing the I2C_IE register on the OMAP4 devices
    *      doesn't seem to actually enable the interrupt, rather you have to write
    *      through the I2C_IRQENABLE_CLR and I2C_IRQENABLE_SET registers.
    *
    *      LOCKING:
    *      No locking required
    *
    *      RETURNS:
    *      Nothing.
    */
   static inline void
   ti_i2c_set_intr_enable(struct ti_i2c_softc *sc, uint16_t ie)
   {
           /* XXXOMAP3: FIXME */
           ti_i2c_write_2(sc, I2C_REG_IRQENABLE_CLR, 0xffff);
           if (ie)
                   ti_i2c_write_2(sc, I2C_REG_IRQENABLE_SET, ie);
   }
   
   /**
    *      ti_i2c_reset - attach function for the driver
    *      @dev: i2c device handle
    *
    *
    *
    *      LOCKING:
    *      Called from timer context
    *
    *      RETURNS:
    *      EH_HANDLED or EH_NOT_HANDLED
    */
   static int
   ti_i2c_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
   {
           struct ti_i2c_softc *sc = device_get_softc(dev);
           struct ti_i2c_clock_config *clkcfg;
           uint16_t con_reg;
   
           clkcfg = ti_i2c_clock_configs;
           while (clkcfg->speed != -1) {
                   if (clkcfg->speed == speed)
                           break;
                   /* take slow if speed is unknown */
                   if ((speed == IIC_UNKNOWN) && (clkcfg->speed == IIC_SLOW))
                           break;
                   clkcfg++;
           }
           if (clkcfg->speed == -1)
                   return (EINVAL);
   
           TI_I2C_LOCK(sc);
   
           if (oldaddr)
                   *oldaddr = sc->sc_i2c_addr;
           sc->sc_i2c_addr = addr;
   
           /* First disable the controller while changing the clocks */
           con_reg = ti_i2c_read_reg(sc, I2C_REG_CON);
           ti_i2c_write_reg(sc, I2C_REG_CON, 0x0000);
   
           /* Program the prescaler */
           ti_i2c_write_reg(sc, I2C_REG_PSC, clkcfg->psc);
   
           /* Set the bitrate */
           ti_i2c_write_reg(sc, I2C_REG_SCLL, clkcfg->scll | (clkcfg->hsscll<<8));
           ti_i2c_write_reg(sc, I2C_REG_SCLH, clkcfg->sclh | (clkcfg->hssclh<<8));
   
           /* Set the remote slave address */
           ti_i2c_write_reg(sc, I2C_REG_SA, addr);
   
           /* Check if we are dealing with high speed mode */
           if ((clkcfg->hsscll + clkcfg->hssclh) > 0)
                   con_reg  = I2C_CON_OPMODE_HS;
           else
                   con_reg  = I2C_CON_OPMODE_STD;
   
           /* Enable the I2C module again */
           ti_i2c_write_reg(sc, I2C_REG_CON, I2C_CON_I2C_EN | con_reg);
   
           TI_I2C_UNLOCK(sc);
   
           return 0;
   }
   
   /**
    *      ti_i2c_intr - interrupt handler for the I2C module
    *      @dev: i2c device handle
    *
    *
    *
    *      LOCKING:
    *      Called from timer context
    *
    *      RETURNS:
    *      EH_HANDLED or EH_NOT_HANDLED
    */
   static void
   ti_i2c_intr(void *arg)
   {
           struct ti_i2c_softc *sc = (struct ti_i2c_softc*) arg;
           uint16_t status;
   
           status = ti_i2c_read_reg(sc, I2C_REG_STAT);
           if (status == 0)
                   return;
   
           TI_I2C_LOCK(sc);
   
           /* save the flags */
           sc->sc_stat_flags |= status;
   
           /* clear the status flags */
           ti_i2c_write_reg(sc, I2C_REG_STAT, status);
   
           /* wakeup the process the started the transaction */
           wakeup(sc);
   
           TI_I2C_UNLOCK(sc);
   
           return;
   }
   
   /**
    *      ti_i2c_wait - waits for the specific event to occur
    *      @sc: i2c driver context
    *      @flags: the event(s) to wait on, this is a bitmask of the I2C_STAT_??? flags
    *      @statp: if not null will contain the status flags upon return
    *      @timo: the number of ticks to wait
    *
    *
    *
    *      LOCKING:
    *      The driver context must be locked before calling this function. Internally
    *      the function sleeps, releasing the lock as it does so, however the lock is
    *      always retaken before this function returns.
    *
    *      RETURNS:
    *      0 if the event(s) were tripped within timeout period
    *      EBUSY if timedout waiting for the events
    *      ENXIO if a NACK event was received
    */
   static int
   ti_i2c_wait(struct ti_i2c_softc *sc, uint16_t flags, uint16_t *statp, int timo)
   {
           int waittime = timo;
           int start_ticks = ticks;
           int rc;
   
           TI_I2C_ASSERT_LOCKED(sc);
   
           /* check if the condition has already occured, the interrupt routine will
            * clear the status flags.
            */
           if ((sc->sc_stat_flags & flags) == 0) {
   
                   /* condition(s) haven't occured so sleep on the IRQ */
                   while (waittime > 0) {
   
                           rc = mtx_sleep(sc, &sc->sc_mtx, 0, "I2Cwait", waittime);
                           if (rc == EWOULDBLOCK) {
                                   /* timed-out, simply break out of the loop */
                                   break;
                           } else {
                                   /* IRQ has been tripped, but need to sanity check we have the
                                    * right events in the status flag.
                                    */
                                   if ((sc->sc_stat_flags & flags) != 0)
                                           break;
   
                                   /* event hasn't been tripped so wait some more */
                                   waittime -= (ticks - start_ticks);
                                   start_ticks = ticks;
                           }
                   }
           }
   
           /* copy the actual status bits */
           if (statp != NULL)
                   *statp = sc->sc_stat_flags;
   
           /* return the status found */
           if ((sc->sc_stat_flags & flags) != 0)
                   rc = 0;
           else
                   rc = EBUSY;
   
           /* clear the flags set by the interrupt handler */
           sc->sc_stat_flags = 0;
   
           return (rc);
   }
   
   /**
    *      ti_i2c_wait_for_free_bus - waits for the bus to become free
    *      @sc: i2c driver context
    *      @timo: the time to wait for the bus to become free
    *
    *
    *
    *      LOCKING:
    *      The driver context must be locked before calling this function. Internally
    *      the function sleeps, releasing the lock as it does so, however the lock is
    *      always taken before this function returns.
    *
    *      RETURNS:
    *      0 if the event(s) were tripped within timeout period
    *      EBUSY if timedout waiting for the events
    *      ENXIO if a NACK event was received
    */
   static int
   ti_i2c_wait_for_free_bus(struct ti_i2c_softc *sc, int timo)
   {
           /* check if the bus is free, BB bit = 0 */
           if ((ti_i2c_read_reg(sc, I2C_REG_STAT) & I2C_STAT_BB) == 0)
                   return 0;
   
           /* enable bus free interrupts */
           ti_i2c_set_intr_enable(sc, I2C_IE_BF);
   
           /* wait for the bus free interrupt to be tripped */
           return ti_i2c_wait(sc, I2C_STAT_BF, NULL, timo);
   }
   
   /**
    *      ti_i2c_read_bytes - attempts to perform a read operation
    *      @sc: i2c driver context
    *      @buf: buffer to hold the received bytes
    *      @len: the number of bytes to read
    *
    *      This function assumes the slave address is already set
    *
    *      LOCKING:
    *      The context lock should be held before calling this function
    *
    *      RETURNS:
    *      0 on function succeeded
    *      EINVAL if invalid message is passed as an arg
    */
   static int
   ti_i2c_read_bytes(struct ti_i2c_softc *sc, uint8_t *buf, uint16_t len)
   {
           int      timo = (hz / 4);
           int      err = 0;
           uint16_t con_reg;
           uint16_t events;
           uint16_t status;
           uint32_t amount = 0;
           uint32_t sofar = 0;
           uint32_t i;
   
           /* wait for the bus to become free */
           err = ti_i2c_wait_for_free_bus(sc, timo);
           if (err != 0) {
                   device_printf(sc->sc_dev, "bus never freed\n");
                   return (err);
           }
   
           /* set the events to wait for */
           events = I2C_IE_RDR |   /* Receive draining interrupt */
                    I2C_IE_RRDY |  /* Receive Data Ready interrupt */
                    I2C_IE_ARDY |  /* Register Access Ready interrupt */
                    I2C_IE_NACK |  /* No Acknowledgment interrupt */
                    I2C_IE_AL;
   
           /* enable interrupts for the events we want */
           ti_i2c_set_intr_enable(sc, events);
   
           /* write the number of bytes to read */
           ti_i2c_write_reg(sc, I2C_REG_CNT, len);
   
           /* clear the write bit and initiate the read transaction. Setting the STT
            * (start) bit initiates the transfer.
            */
           con_reg = ti_i2c_read_reg(sc, I2C_REG_CON);
           con_reg &= ~I2C_CON_TRX;
           con_reg |=  I2C_CON_MST | I2C_CON_STT | I2C_CON_STP;
           ti_i2c_write_reg(sc, I2C_REG_CON, con_reg);
   
           /* reading loop */
           while (1) {
   
                   /* wait for an event */
                   err = ti_i2c_wait(sc, events, &status, timo);
                   if (err != 0) {
                           break;
                   }
   
                   /* check for the error conditions */
                   if (status & I2C_STAT_NACK) {
                           /* no ACK from slave */
                           ti_i2c_dbg(sc, "NACK\n");
                           err = ENXIO;
                           break;
                   }
                   if (status & I2C_STAT_AL) {
                           /* arbitration lost */
                           ti_i2c_dbg(sc, "Arbitration lost\n");
                           err = ENXIO;
                           break;
                   }
   
                   /* check if we have finished */
                   if (status & I2C_STAT_ARDY) {
                           /* register access ready - transaction complete basically */
                           ti_i2c_dbg(sc, "ARDY transaction complete\n");
                           err = 0;
                           break;
                   }
   
                   /* read some data */
                   if (status & I2C_STAT_RDR) {
                           /* Receive draining interrupt - last data received */
                           ti_i2c_dbg(sc, "Receive draining interrupt\n");
   
                           /* get the number of bytes in the FIFO */
                           amount = ti_i2c_read_reg(sc, I2C_REG_BUFSTAT);
                           amount >>= 8;
                           amount &= 0x3f;
                   }
                   else if (status & I2C_STAT_RRDY) {
                           /* Receive data ready interrupt - enough data received */
                           ti_i2c_dbg(sc, "Receive data ready interrupt\n");
   
                           /* get the number of bytes in the FIFO */
                           amount = ti_i2c_read_reg(sc, I2C_REG_BUF);
                           amount >>= 8;
                           amount &= 0x3f;
                           amount += 1;
                   }
   
                   /* sanity check we haven't overwritten the array */
                   if ((sofar + amount) > len) {
                           ti_i2c_dbg(sc, "to many bytes to read\n");
                           amount = (len - sofar);
                   }
   
                   /* read the bytes from the fifo */
                   for (i = 0; i < amount; i++) {
                           buf[sofar++] = (uint8_t)(ti_i2c_read_reg(sc, I2C_REG_DATA) & 0xff);
                   }
   
                   /* attempt to clear the receive ready bits */
                   ti_i2c_write_reg(sc, I2C_REG_STAT, I2C_STAT_RDR | I2C_STAT_RRDY);
           }
   
           /* reset the registers regardless if there was an error or not */
           ti_i2c_set_intr_enable(sc, 0x0000);
           ti_i2c_write_reg(sc, I2C_REG_CON, I2C_CON_I2C_EN | I2C_CON_MST | I2C_CON_STP);
   
           return (err);
   }
   
   /**
    *      ti_i2c_write_bytes - attempts to perform a read operation
    *      @sc: i2c driver context
    *      @buf: buffer containing the bytes to write
    *      @len: the number of bytes to write
    *
    *      This function assumes the slave address is already set
    *
    *      LOCKING:
    *      The context lock should be held before calling this function
    *
    *      RETURNS:
    *      0 on function succeeded
    *      EINVAL if invalid message is passed as an arg
    */
   static int
   ti_i2c_write_bytes(struct ti_i2c_softc *sc, const uint8_t *buf, uint16_t len)
   {
           int      timo = (hz / 4);
           int      err = 0;
           uint16_t con_reg;
           uint16_t events;
           uint16_t status;
           uint32_t amount = 0;
           uint32_t sofar = 0;
           uint32_t i;
   
           /* wait for the bus to become free */
           err = ti_i2c_wait_for_free_bus(sc, timo);
           if (err != 0)
                   return (err);
   
           /* set the events to wait for */
           events = I2C_IE_XDR |   /* Transmit draining interrupt */
                    I2C_IE_XRDY |  /* Transmit Data Ready interrupt */
                    I2C_IE_ARDY |  /* Register Access Ready interrupt */
                    I2C_IE_NACK |  /* No Acknowledgment interrupt */
                    I2C_IE_AL;
   
           /* enable interrupts for the events we want*/
           ti_i2c_set_intr_enable(sc, events);
   
           /* write the number of bytes to write */
           ti_i2c_write_reg(sc, I2C_REG_CNT, len);
   
           /* set the write bit and initiate the write transaction. Setting the STT
            * (start) bit initiates the transfer.
            */
           con_reg = ti_i2c_read_reg(sc, I2C_REG_CON);
           con_reg |= I2C_CON_TRX | I2C_CON_MST | I2C_CON_STT | I2C_CON_STP;
           ti_i2c_write_reg(sc, I2C_REG_CON, con_reg);
   
           /* writing loop */
           while (1) {
   
                   /* wait for an event */
                   err = ti_i2c_wait(sc, events, &status, timo);
                   if (err != 0) {
                           break;
                   }
   
                   /* check for the error conditions */
                   if (status & I2C_STAT_NACK) {
                           /* no ACK from slave */
                           ti_i2c_dbg(sc, "NACK\n");
                           err = ENXIO;
                           break;
                   }
                   if (status & I2C_STAT_AL) {
                           /* arbitration lost */
                           ti_i2c_dbg(sc, "Arbitration lost\n");
                           err = ENXIO;
                           break;
                   }
   
                   /* check if we have finished */
                   if (status & I2C_STAT_ARDY) {
                           /* register access ready - transaction complete basically */
                           ti_i2c_dbg(sc, "ARDY transaction complete\n");
                           err = 0;
                           break;
                   }
   
                   /* read some data */
                   if (status & I2C_STAT_XDR) {
                           /* Receive draining interrupt - last data received */
                           ti_i2c_dbg(sc, "Transmit draining interrupt\n");
   
                           /* get the number of bytes in the FIFO */
                           amount = ti_i2c_read_reg(sc, I2C_REG_BUFSTAT);
                           amount &= 0x3f;
                   }
                   else if (status & I2C_STAT_XRDY) {
                           /* Receive data ready interrupt - enough data received */
                           ti_i2c_dbg(sc, "Transmit data ready interrupt\n");
   
                           /* get the number of bytes in the FIFO */
                           amount = ti_i2c_read_reg(sc, I2C_REG_BUF);
                           amount &= 0x3f;
                           amount += 1;
                   }
   
                   /* sanity check we haven't overwritten the array */
                   if ((sofar + amount) > len) {
                           ti_i2c_dbg(sc, "to many bytes to write\n");
                           amount = (len - sofar);
                   }
   
                   /* write the bytes from the fifo */
                   for (i = 0; i < amount; i++) {
                           ti_i2c_write_reg(sc, I2C_REG_DATA, buf[sofar++]);
                   }
   
                   /* attempt to clear the transmit ready bits */
                   ti_i2c_write_reg(sc, I2C_REG_STAT, I2C_STAT_XDR | I2C_STAT_XRDY);
           }
   
           /* reset the registers regardless if there was an error or not */
           ti_i2c_set_intr_enable(sc, 0x0000);
           ti_i2c_write_reg(sc, I2C_REG_CON, I2C_CON_I2C_EN | I2C_CON_MST | I2C_CON_STP);
   
           return (err);
   }
   
   /**
    *      ti_i2c_transfer - called to perform the transfer
    *      @dev: i2c device handle
    *      @msgs: the messages to send/receive
    *      @nmsgs: the number of messages in the msgs array
    *
    *
    *      LOCKING:
    *      Internally locked
    *
    *      RETURNS:
    *      0 on function succeeded
    *      EINVAL if invalid message is passed as an arg
    */
   static int
   ti_i2c_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
   {
           struct ti_i2c_softc *sc = device_get_softc(dev);
           int err = 0;
           uint32_t i;
           uint16_t len;
           uint8_t *buf;
   
           TI_I2C_LOCK(sc);
   
           for (i = 0; i < nmsgs; i++) {
   
                   len = msgs[i].len;
                   buf = msgs[i].buf;
   
                   /* zero byte transfers aren't allowed */
                   if (len == 0 || buf == NULL) {
                           err = EINVAL;
                           goto out;
                   }
   
                   /* set the slave address */
                   ti_i2c_write_reg(sc, I2C_REG_SA, msgs[i].slave);
   
                   /* perform the read or write */
                   if (msgs[i].flags & IIC_M_RD) {
                           err = ti_i2c_read_bytes(sc, buf, len);
                   } else {
                           err = ti_i2c_write_bytes(sc, buf, len);
                   }
   
           }
   
   out:
           TI_I2C_UNLOCK(sc);
   
           return (err);
   }
   
   /**
    *      ti_i2c_callback - not sure about this one
    *      @dev: i2c device handle
    *
    *
    *
    *      LOCKING:
    *      Called from timer context
    *
    *      RETURNS:
    *      EH_HANDLED or EH_NOT_HANDLED
    */
   static int
   ti_i2c_callback(device_t dev, int index, caddr_t data)
   {
           int error = 0;
   
           switch (index) {
                   case IIC_REQUEST_BUS:
                           break;
   
                   case IIC_RELEASE_BUS:
                           break;
   
                   default:
                           error = EINVAL;
           }
   
           return (error);
   }
   
   /**
    *      ti_i2c_activate - initialises and activates an I2C bus
    *      @dev: i2c device handle
    *      @num: the number of the I2C controller to activate; 1, 2 or 3
    *
    *
    *      LOCKING:
    *      Assumed called in an atomic context.
    *
    *      RETURNS:
    *      nothing
    */
   static int
   ti_i2c_activate(device_t dev)
   {
           struct ti_i2c_softc *sc = (struct ti_i2c_softc*) device_get_softc(dev);
           unsigned int timeout = 0;
           uint16_t con_reg;
           int err;
           clk_ident_t clk;
   
           /*
            * The following sequence is taken from the OMAP3530 technical reference
            *
            * 1. Enable the functional and interface clocks (see Section 18.3.1.1.1).
            */
           clk = I2C0_CLK + sc->device_id;
           err = ti_prcm_clk_enable(clk);
           if (err)
                   return (err);
   
           /* There seems to be a bug in the I2C reset mechanism, for some reason you
            * need to disable the I2C module before issuing the reset and then enable
            * it again after to detect the reset done.
            *
            * I found this out by looking at the Linux driver implementation, thanks
            * linux guys!
            */
   
           /* Disable the I2C controller */
           ti_i2c_write_reg(sc, I2C_REG_CON, 0x0000);
   
           /* Issue a softreset to the controller */
           /* XXXOMAP3: FIXME */
           bus_write_2(sc->sc_mem_res, I2C_REG_SYSC, 0x0002);
   
           /* Re-enable the module and then check for the reset done */
           ti_i2c_write_reg(sc, I2C_REG_CON, I2C_CON_I2C_EN);
   
           while ((ti_i2c_read_reg(sc, I2C_REG_SYSS) & 0x01) == 0x00) {
                   if (timeout++ > 100) {
                           return (EBUSY);
                   }
                   DELAY(100);
           }
   
           /* Disable the I2C controller once again, now that the reset has finished */
           ti_i2c_write_reg(sc, I2C_REG_CON, 0x0000);
   
           /* 2. Program the prescaler to obtain an approximately 12-MHz internal
            *    sampling clock (I2Ci_INTERNAL_CLK) by programming the corresponding
            *    value in the I2Ci.I2C_PSC[3:0] PSC field.
            *    This value depends on the frequency of the functional clock (I2Ci_FCLK).
            *    Because this frequency is 96MHz, the I2Ci.I2C_PSC[7:0] PSC field value
            *    is 0x7.
            */
   
           /* Program the prescaler to obtain an approximately 12-MHz internal
            * sampling clock.
            */
           ti_i2c_write_reg(sc, I2C_REG_PSC, 0x0017);
   
           /* 3. Program the I2Ci.I2C_SCLL[7:0] SCLL and I2Ci.I2C_SCLH[7:0] SCLH fields
            *    to obtain a bit rate of 100K bps or 400K bps. These values depend on
            *    the internal sampling clock frequency (see Table 18-12).
            */
   
           /* Set the bitrate to 100kbps */
           ti_i2c_write_reg(sc, I2C_REG_SCLL, 0x000d);
           ti_i2c_write_reg(sc, I2C_REG_SCLH, 0x000f);
   
           /* 4. (Optional) Program the I2Ci.I2C_SCLL[15:8] HSSCLL and
            *    I2Ci.I2C_SCLH[15:8] HSSCLH fields to obtain a bit rate of 400K bps or
            *    3.4M bps (for the second phase of HS mode). These values depend on the
            *    internal sampling clock frequency (see Table 18-12).
            *
            * 5. (Optional) If a bit rate of 3.4M bps is used and the bus line
            *    capacitance exceeds 45 pF, program the CONTROL.CONTROL_DEVCONF1[12]
            *    I2C1HSMASTER bit for I2C1, the CONTROL.CONTROL_DEVCONF1[13]
            *    I2C2HSMASTER bit for I2C2, or the CONTROL.CONTROL_DEVCONF1[14]
            *    I2C3HSMASTER bit for I2C3.
            */
   
           /* 6. Configure the Own Address of the I2C controller by storing it in the
            *    I2Ci.I2C_OA0 register. Up to four Own Addresses can be programmed in
            *    the I2Ci.I2C_OAi registers (with I = 0, 1, 2, 3) for each I2C
            *    controller.
            *
            * Note: For a 10-bit address, set the corresponding expand Own Address bit
            * in the I2Ci.I2C_CON register.
            */
   
           /* Driver currently always in single master mode so ignore this step */
   
           /* 7. Set the TX threshold (in transmitter mode) and the RX threshold (in
            *    receiver mode) by setting the I2Ci.I2C_BUF[5:0]XTRSH field to (TX
            *    threshold - 1) and the I2Ci.I2C_BUF[13:8]RTRSH field to (RX threshold
            *    - 1), where the TX and RX thresholds are greater than or equal to 1.
            */
   
           /* Set the FIFO buffer threshold, note I2C1 & I2C2 have 8 byte FIFO, whereas
            * I2C3 has 64 bytes.  Threshold set to 5 for now.
            */
           ti_i2c_write_reg(sc, I2C_REG_BUF, 0x0404);
   
           /*
            * 8. Take the I2C controller out of reset by setting the I2Ci.I2C_CON[15]
            *    I2C_EN bit to 1.
            */
           ti_i2c_write_reg(sc, I2C_REG_CON, I2C_CON_I2C_EN | I2C_CON_OPMODE_STD);
   
           /*
            * To initialize the I2C controller, perform the following steps:
            *
            * 1. Configure the I2Ci.I2C_CON register:
            *    · For master or slave mode, set the I2Ci.I2C_CON[10] MST bit (0: slave,
            *      1: master).
            *    · For transmitter or receiver mode, set the I2Ci.I2C_CON[9] TRX bit
            *      (0: receiver, 1: transmitter).
            */
           con_reg = ti_i2c_read_reg(sc, I2C_REG_CON);
           con_reg |= I2C_CON_MST;
           ti_i2c_write_reg(sc, I2C_REG_CON, con_reg);
   
           /* 2. If using an interrupt to transmit/receive data, set to 1 the
            *    corresponding bit in the I2Ci.I2C_IE register (the I2Ci.I2C_IE[4]
            *    XRDY_IE bit for the transmit interrupt, the I2Ci.I2C_IE[3] RRDY bit
            *    for the receive interrupt).
            */
           ti_i2c_set_intr_enable(sc, I2C_IE_XRDY | I2C_IE_RRDY);
   
           /* 3. If using DMA to receive/transmit data, set to 1 the corresponding bit
            *    in the I2Ci.I2C_BUF register (the I2Ci.I2C_BUF[15] RDMA_EN bit for the
            *    receive DMA channel, the I2Ci.I2C_BUF[7] XDMA_EN bit for the transmit
            *    DMA channel).
            */
   
           /* not using DMA for now, so ignore this */
   
           return (0);
   }
   
   /**
    *      ti_i2c_deactivate - deactivates the controller and releases resources
    *      @dev: i2c device handle
    *
    *
    *
    *      LOCKING:
    *      Assumed called in an atomic context.
    *
    *      RETURNS:
    *      nothing
    */
   static void
   ti_i2c_deactivate(device_t dev)
   {
           struct ti_i2c_softc *sc = device_get_softc(dev);
           clk_ident_t clk;
   
           /* Disable the controller - cancel all transactions */
           ti_i2c_write_reg(sc, I2C_REG_CON, 0x0000);
   
           /* Release the interrupt handler */
           if (sc->sc_irq_h) {
                   bus_teardown_intr(dev, sc->sc_irq_res, sc->sc_irq_h);
                   sc->sc_irq_h = 0;
           }
   
           bus_generic_detach(sc->sc_dev);
   
           /* Unmap the I2C controller registers */
           if (sc->sc_mem_res != 0) {
                   bus_release_resource(dev, SYS_RES_MEMORY, rman_get_rid(sc->sc_irq_res),
                                                            sc->sc_mem_res);
                   sc->sc_mem_res = NULL;
           }
   
           /* Release the IRQ resource */
           if (sc->sc_irq_res != NULL) {
                   bus_release_resource(dev, SYS_RES_IRQ, rman_get_rid(sc->sc_irq_res),
                                                            sc->sc_irq_res);
                   sc->sc_irq_res = NULL;
           }
  
          /* Finally disable the functional and interface clocks */
          clk = I2C0_CLK + sc->device_id;
          ti_prcm_clk_disable(clk);
  
          return;
  }
  
  /**
   *      ti_i2c_probe - probe function for the driver
   *      @dev: i2c device handle
   *
   *
   *
   *      LOCKING:
   *
   *
   *      RETURNS:
   *      Always returns 0
   */
  static int
  ti_i2c_probe(device_t dev)
  {
          if (!ofw_bus_is_compatible(dev, "ti,i2c"))
                  return (ENXIO);
  
          device_set_desc(dev, "TI I2C Controller");
          return (0);
  }
  
  /**
   *      ti_i2c_attach - attach function for the driver
   *      @dev: i2c device handle
   *
   *      Initialised driver data structures and activates the I2C controller.
   *
   *      LOCKING:
   *
   *
   *      RETURNS:
   *
   */
  static int
  ti_i2c_attach(device_t dev)
  {
          struct ti_i2c_softc *sc = device_get_softc(dev);
          phandle_t node;
          pcell_t did;
          int err;
          int rid;
  
          sc->sc_dev = dev;
  
          /* Get the i2c device id from FDT */
          node = ofw_bus_get_node(dev);
          if ((OF_getprop(node, "i2c-device-id", &did, sizeof(did))) <= 0) {
                  device_printf(dev, "missing i2c-device-id attribute in FDT\n");
                  return (ENXIO);
          }
          sc->device_id = fdt32_to_cpu(did);
  
          TI_I2C_LOCK_INIT(sc);
  
          /* Get the memory resource for the register mapping */
          rid = 0;
          sc->sc_mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid,
                                                  RF_ACTIVE);
          if (sc->sc_mem_res == NULL)
                  panic("%s: Cannot map registers", device_get_name(dev));
  
          /* Allocate an IRQ resource for the MMC controller */
          rid = 0;
          sc->sc_irq_res = bus_alloc_resource_any(dev, SYS_RES_IRQ, &rid,
                                                  RF_ACTIVE | RF_SHAREABLE);
          if (sc->sc_irq_res == NULL) {
                  err = ENOMEM;
                  goto out;
          }
  
          /* XXXOMAP3: FIXME get proper revision here */
          /* First read the version number of the I2C module */
          sc->sc_rev = ti_i2c_read_2(sc, I2C_REG_REVNB_HI) & 0xff;
  
          device_printf(dev, "I2C revision %d.%d\n", sc->sc_rev >> 4,
              sc->sc_rev & 0xf);
  
          /* Activate the H/W */
          err = ti_i2c_activate(dev);
          if (err) {
                  device_printf(dev, "ti_i2c_activate failed\n");
                  goto out;
          }
  
          /* activate the interrupt */
          err = bus_setup_intr(dev, sc->sc_irq_res, INTR_TYPE_MISC | INTR_MPSAFE,
                                  NULL, ti_i2c_intr, sc, &sc->sc_irq_h);
          if (err)
                  goto out;
  
          /* Attach to the iicbus */
          if ((sc->sc_iicbus = device_add_child(dev, "iicbus", -1)) == NULL)
                  device_printf(dev, "could not allocate iicbus instance\n");
  
          /* Probe and attach the iicbus */
          bus_generic_attach(dev);
  
  out:
          if (err) {
                  ti_i2c_deactivate(dev);
                  TI_I2C_LOCK_DESTROY(sc);
          }
  
          return (err);
  }
  
  /**
   *      ti_i2c_detach - detach function for the driver
   *      @dev: i2c device handle
   *
   *
   *
   *      LOCKING:
   *
   *
   *      RETURNS:
   *      Always returns 0
   */
  static int
  ti_i2c_detach(device_t dev)
  {
          struct ti_i2c_softc *sc = device_get_softc(dev);
          int rv;
  
          ti_i2c_deactivate(dev);
  
          if (sc->sc_iicbus && (rv = device_delete_child(dev, sc->sc_iicbus)) != 0)
                  return (rv);
  
          TI_I2C_LOCK_DESTROY(sc);
  
          return (0);
  }
  
  
  static phandle_t
  ti_i2c_get_node(device_t bus, device_t dev)
  {
          /* 
           * Share controller node with iibus device
           */
          return ofw_bus_get_node(bus);
  }
  
  static device_method_t ti_i2c_methods[] = {
          /* Device interface */
          DEVMETHOD(device_probe,         ti_i2c_probe),
          DEVMETHOD(device_attach,        ti_i2c_attach),
          DEVMETHOD(device_detach,        ti_i2c_detach),
  
          /* OFW methods */
          DEVMETHOD(ofw_bus_get_node,     ti_i2c_get_node),
  
          /* iicbus interface */
          DEVMETHOD(iicbus_callback,      ti_i2c_callback),
          DEVMETHOD(iicbus_reset,         ti_i2c_reset),
          DEVMETHOD(iicbus_transfer,      ti_i2c_transfer),
          { 0, 0 }
  };
  
  static driver_t ti_i2c_driver = {
          "iichb",
          ti_i2c_methods,
          sizeof(struct ti_i2c_softc),
  };
  
  DRIVER_MODULE(ti_iic, simplebus, ti_i2c_driver, ti_i2c_devclass, 0, 0);
  DRIVER_MODULE(iicbus, ti_iic, iicbus_driver, iicbus_devclass, 0, 0);
  
  MODULE_DEPEND(ti_iic, ti_prcm, 1, 1, 1);
  MODULE_DEPEND(ti_iic, iicbus, 1, 1, 1);

Cache object: d6fdbe63edd1bcee9622258bed15036b