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  •  * i2c.c - driver for ADI TWI/I2C
    
     * Copyright (c) 2006-2014 Analog Devices Inc.
    
     *
     * Licensed under the GPL-2 or later.
     */
    
    #include <common.h>
    #include <i2c.h>
    
    
    #include <asm/clock.h>
    
    #include <asm/twi.h>
    
    #include <asm/io.h>
    
    /* Every register is 32bit aligned, but only 16bits in size */
    #define ureg(name) u16 name; u16 __pad_##name;
    struct twi_regs {
    	ureg(clkdiv);
    	ureg(control);
    	ureg(slave_ctl);
    	ureg(slave_stat);
    	ureg(slave_addr);
    	ureg(master_ctl);
    	ureg(master_stat);
    	ureg(master_addr);
    	ureg(int_stat);
    	ureg(int_mask);
    	ureg(fifo_ctl);
    	ureg(fifo_stat);
    	char __pad[0x50];
    	ureg(xmt_data8);
    	ureg(xmt_data16);
    	ureg(rcv_data8);
    	ureg(rcv_data16);
    };
    #undef ureg
    
    /* U-Boot I2C framework allows only one active device at a time.  */
    #ifdef TWI_CLKDIV
    #define TWI0_CLKDIV TWI_CLKDIV
    #endif
    
    static struct twi_regs *twi = (void *)TWI0_CLKDIV;
    
    #ifdef DEBUG
    # define dmemset(s, c, n) memset(s, c, n)
    #else
    # define dmemset(s, c, n)
    #endif
    #define debugi(fmt, args...) \
    	debug( \
    
    		"MSTAT:0x%03x FSTAT:0x%x ISTAT:0x%02x\t%-20s:%-3i: " fmt "\n", \
    		twi->master_stat, twi->fifo_stat, twi->int_stat, \
    
    		__func__, __LINE__, ## args)
    
    #ifdef CONFIG_TWICLK_KHZ
    # error do not define CONFIG_TWICLK_KHZ ... use CONFIG_SYS_I2C_SPEED
    #endif
    
    
    /*
     * The way speed is changed into duty often results in integer truncation
     * with 50% duty, so we'll force rounding up to the next duty by adding 1
     * to the max.  In practice this will get us a speed of something like
     * 385 KHz.  The other limit is easy to handle as it is only 8 bits.
     */
    #define I2C_SPEED_MAX             400000
    #define I2C_SPEED_TO_DUTY(speed)  (5000000 / (speed))
    #define I2C_DUTY_MAX              (I2C_SPEED_TO_DUTY(I2C_SPEED_MAX) + 1)
    #define I2C_DUTY_MIN              0xff	/* 8 bit limited */
    #define SYS_I2C_DUTY              I2C_SPEED_TO_DUTY(CONFIG_SYS_I2C_SPEED)
    /* Note: duty is inverse of speed, so the comparisons below are correct */
    #if SYS_I2C_DUTY < I2C_DUTY_MAX || SYS_I2C_DUTY > I2C_DUTY_MIN
    # error "The Blackfin I2C hardware can only operate 20KHz - 400KHz"
    
    #endif
    
    /* All transfers are described by this data structure */
    struct i2c_msg {
    	u8 flags;
    #define I2C_M_COMBO		0x4
    #define I2C_M_STOP		0x2
    #define I2C_M_READ		0x1
    	int len;		/* msg length */
    	u8 *buf;		/* pointer to msg data */
    	int alen;		/* addr length */
    	u8 *abuf;		/* addr buffer */
    };
    
    
    /* Allow msec timeout per ~byte transfer */
    #define I2C_TIMEOUT 10
    
    
    /**
     * wait_for_completion - manage the actual i2c transfer
     *	@msg: the i2c msg
     */
    static int wait_for_completion(struct i2c_msg *msg)
    {
    
    	u16 int_stat, ctl;
    
    	ulong timebase = get_timer(0);
    
    		int_stat = readw(&twi->int_stat);
    
    
    		if (int_stat & XMTSERV) {
    			debugi("processing XMTSERV");
    
    			writew(XMTSERV, &twi->int_stat);
    
    			if (msg->alen) {
    
    				writew(*(msg->abuf++), &twi->xmt_data8);
    
    				--msg->alen;
    			} else if (!(msg->flags & I2C_M_COMBO) && msg->len) {
    
    				writew(*(msg->buf++), &twi->xmt_data8);
    
    				--msg->len;
    			} else {
    
    				ctl = readw(&twi->master_ctl);
    				if (msg->flags & I2C_M_COMBO)
    					writew(ctl | RSTART | MDIR,
    							&twi->master_ctl);
    				else
    					writew(ctl | STOP, &twi->master_ctl);
    
    			}
    		}
    		if (int_stat & RCVSERV) {
    			debugi("processing RCVSERV");
    
    			writew(RCVSERV, &twi->int_stat);
    
    			if (msg->len) {
    
    				*(msg->buf++) = readw(&twi->rcv_data8);
    
    				--msg->len;
    			} else if (msg->flags & I2C_M_STOP) {
    
    				ctl = readw(&twi->master_ctl);
    				writew(ctl | STOP, &twi->master_ctl);
    
    			}
    		}
    		if (int_stat & MERR) {
    			debugi("processing MERR");
    
    			writew(MERR, &twi->int_stat);
    
    			return msg->len;
    
    		}
    		if (int_stat & MCOMP) {
    			debugi("processing MCOMP");
    
    			writew(MCOMP, &twi->int_stat);
    
    			if (msg->flags & I2C_M_COMBO && msg->len) {
    
    				ctl = readw(&twi->master_ctl);
    				ctl = (ctl & ~RSTART) |
    
    					(min(msg->len, 0xff) << 6) | MEN | MDIR;
    
    				writew(ctl, &twi->master_ctl);
    
    			} else
    				break;
    		}
    
    
    		/* If we were able to do something, reset timeout */
    		if (int_stat)
    			timebase = get_timer(0);
    
    	} while (get_timer(timebase) < I2C_TIMEOUT);
    
    
    	return msg->len;
    }
    
    /**
     * i2c_transfer - setup an i2c transfer
     *	@return: 0 if things worked, non-0 if things failed
     *
     *	Here we just get the i2c stuff all prepped and ready, and then tail off
     *	into wait_for_completion() for all the bits to go.
     */
    
    static int i2c_transfer(uchar chip, uint addr, int alen, uchar *buffer,
    			int len, u8 flags)
    
    	uchar addr_buffer[] = {
    		(addr >>  0),
    		(addr >>  8),
    		(addr >> 16),
    	};
    	struct i2c_msg msg = {
    		.flags = flags | (len >= 0xff ? I2C_M_STOP : 0),
    		.buf   = buffer,
    		.len   = len,
    		.abuf  = addr_buffer,
    		.alen  = alen,
    	};
    
    	dmemset(buffer, 0xff, len);
    
    	debugi("chip=0x%x addr=0x%02x alen=%i buf[0]=0x%02x len=%i ",
    		chip, addr, alen, buffer[0], len);
    	debugi("flags=0x%02x[%s] ", flags,
    		(flags & I2C_M_READ ? "rd" : "wr"));
    
    
    	/* wait for things to settle */
    
    	while (readw(&twi->master_stat) & BUSBUSY)
    
    		if (ctrlc())
    			return 1;
    
    	/* Set Transmit device address */
    
    	writew(chip, &twi->master_addr);
    
    
    	/* Clear the FIFO before starting things */
    
    	writew(XMTFLUSH | RCVFLUSH, &twi->fifo_ctl);
    	writew(0, &twi->fifo_ctl);
    
    
    	/* prime the pump */
    	if (msg.alen) {
    
    		len = (msg.flags & I2C_M_COMBO) ? msg.alen : msg.alen + len;
    
    		debugi("first byte=0x%02x", *msg.abuf);
    
    		writew(*(msg.abuf++), &twi->xmt_data8);
    
    		--msg.alen;
    	} else if (!(msg.flags & I2C_M_READ) && msg.len) {
    		debugi("first byte=0x%02x", *msg.buf);
    
    		writew(*(msg.buf++), &twi->xmt_data8);
    
    		--msg.len;
    	}
    
    	/* clear int stat */
    
    	writew(-1, &twi->master_stat);
    	writew(-1, &twi->int_stat);
    	writew(0, &twi->int_mask);
    
    
    	/* Master enable */
    
    	ctl = readw(&twi->master_ctl);
    	ctl = (ctl & FAST) | (min(len, 0xff) << 6) | MEN |
    		((msg.flags & I2C_M_READ) ? MDIR : 0);
    	writew(ctl, &twi->master_ctl);
    
    
    	/* process the rest */
    	ret = wait_for_completion(&msg);
    	debugi("ret=%d", ret);
    
    	if (ret) {
    
    		ctl = readw(&twi->master_ctl) & ~MEN;
    		writew(ctl, &twi->master_ctl);
    		ctl = readw(&twi->control) & ~TWI_ENA;
    		writew(ctl, &twi->control);
    		ctl = readw(&twi->control) | TWI_ENA;
    		writew(ctl, &twi->control);
    
    /**
     * i2c_set_bus_speed - set i2c bus speed
     *	@speed: bus speed (in HZ)
     */
    int i2c_set_bus_speed(unsigned int speed)
    {
    	u16 clkdiv = I2C_SPEED_TO_DUTY(speed);
    
    	/* Set TWI interface clock */
    	if (clkdiv < I2C_DUTY_MAX || clkdiv > I2C_DUTY_MIN)
    		return -1;
    
    	clkdiv = (clkdiv << 8) | (clkdiv & 0xff);
    	writew(clkdiv, &twi->clkdiv);
    
    	writew(speed > 100000 ? FAST : 0, &twi->master_ctl);
    
    
    	return 0;
    }
    
    /**
     * i2c_get_bus_speed - get i2c bus speed
     *	@speed: bus speed (in HZ)
     */
    unsigned int i2c_get_bus_speed(void)
    {
    
    	u16 clkdiv = readw(&twi->clkdiv) & 0xff;
    
    	/* 10 MHz / (2 * CLKDIV) -> 5 MHz / CLKDIV */
    
    	return 5000000 / clkdiv;
    
     * i2c_init - initialize the i2c bus
     *	@speed: bus speed (in HZ)
     *	@slaveaddr: address of device in slave mode (0 - not slave)
     *
     *	Slave mode isn't actually implemented.  It'll stay that way until
     *	we get a real request for it.
     */
    void i2c_init(int speed, int slaveaddr)
    {
    
    	uint8_t prescale = ((get_i2c_clk() / 1000 / 1000 + 5) / 10) & 0x7F;
    
    
    	/* Set TWI internal clock as 10MHz */
    
    	writew(prescale, &twi->control);
    
    
    	/* Set TWI interface clock as specified */
    
    	i2c_set_bus_speed(speed);
    
    	writew(TWI_ENA | prescale, &twi->control);
    
    	debugi("CONTROL:0x%04x CLKDIV:0x%04x", readw(&twi->control),
    		readw(&twi->clkdiv));
    
    
    #if CONFIG_SYS_I2C_SLAVE
    # error I2C slave support not tested/supported
    #endif
    }
    
    /**
     * i2c_probe - test if a chip exists at a given i2c address
     *	@chip: i2c chip addr to search for
     *	@return: 0 if found, non-0 if not found
     */
    int i2c_probe(uchar chip)
    {
    	u8 byte;
    	return i2c_read(chip, 0, 0, &byte, 1);
    }
    
    /**
     * i2c_read - read data from an i2c device
     *	@chip: i2c chip addr
     *	@addr: memory (register) address in the chip
     *	@alen: byte size of address
     *	@buffer: buffer to store data read from chip
     *	@len: how many bytes to read
     *	@return: 0 on success, non-0 on failure
     */
    int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
    {
    
    	return i2c_transfer(chip, addr, alen, buffer,
    			len, (alen ? I2C_M_COMBO : I2C_M_READ));
    
    }
    
    /**
     * i2c_write - write data to an i2c device
     *	@chip: i2c chip addr
     *	@addr: memory (register) address in the chip
     *	@alen: byte size of address
    
     *	@buffer: buffer holding data to write to chip
    
     *	@len: how many bytes to write
     *	@return: 0 on success, non-0 on failure
     */
    int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
    {
    	return i2c_transfer(chip, addr, alen, buffer, len, 0);
    }
    
    
    /**
     * i2c_set_bus_num - change active I2C bus
     *	@bus: bus index, zero based
     *	@returns: 0 on success, non-0 on failure
     */
    int i2c_set_bus_num(unsigned int bus)
    {
    	switch (bus) {
    #if CONFIG_SYS_MAX_I2C_BUS > 0
    
    	case 0:
    		twi = (void *)TWI0_CLKDIV;
    		return 0;
    
    #endif
    #if CONFIG_SYS_MAX_I2C_BUS > 1
    
    	case 1:
    		twi = (void *)TWI1_CLKDIV;
    		return 0;
    
    #endif
    #if CONFIG_SYS_MAX_I2C_BUS > 2
    
    	case 2:
    		twi = (void *)TWI2_CLKDIV;
    		return 0;
    
    	default: return -1;
    
    	}
    }
    
    /**
     * i2c_get_bus_num - returns index of active I2C bus
     */
    unsigned int i2c_get_bus_num(void)
    {
    	switch ((unsigned long)twi) {
    #if CONFIG_SYS_MAX_I2C_BUS > 0
    
    	case TWI0_CLKDIV:
    		return 0;
    
    #endif
    #if CONFIG_SYS_MAX_I2C_BUS > 1
    
    	case TWI1_CLKDIV:
    		return 1;
    
    #endif
    #if CONFIG_SYS_MAX_I2C_BUS > 2
    
    	case TWI2_CLKDIV:
    		return 2;
    
    	default: return -1;