~foura/uxn900

ref: b0cfe4adf7d74b0c75b7083b5f15376f4a05c6bd uxn900/src/i2c.c -rw-r--r-- 5.5 KiB
b0cfe4adjames palmer i2c: slight refactoring, read works now! :) 4 months ago
                                                                                
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#include "uxn.h"
#include "dat.h"
#include "fns.h"

#include "dev/console.h"

enum {
	Rrev     = 0x00,
	Rie      = 0x04,
		Riexrdy = 1 << 4, /* tx ready */
		Rierrdy = 1 << 3, /* rx ready */
		Rieardy = 1 << 2, /* register access ready */
		Rienack = 1 << 1, /* no acknowledgment */
		Rieal   = 1 << 0, /* arbitration lost */
	Rstat    = 0x08,
		Rstatsbd  = 1 << 15, /* single byte data */
		Rstatbb   = 1 << 12, /* bus busy */
		Rstatrovr = 1 << 11, /* receive overrun */
		Rstatxudf = 1 << 10, /* transmit underflow */
		Rstataas  = 1 << 9,  /* address as slave */
		Rstatxrdy = 1 << 4, /* tx ready */
		Rstatrrdy = 1 << 3, /* rx ready */
		Rstatardy = 1 << 2, /* register access ready */
		Rstatnack = 1 << 1, /* no acknowledgment */
		Rstatal   = 1 << 0, /* arbitration lost */
	Rwe      = 0x0c,
	Rsyss    = 0x10,
		Rsyssrdone = 1 << 0, /* reset monitoring */
	Rbuf     = 0x14,
		Rbufrdma = 1 << 15,  /* recieve dma */
		Rbufxdma = 1 << 7,   /* transmit dma */
	Rcnt     = 0x18,
	Rdata    = 0x1c,
	Rsysc    = 0x20,
	Rcon     = 0x24,
		Rconen  = 1 << 15, /* module enable */
		Rconbe  = 1 << 14, /* big endian mode */
		Rconstb = 1 << 11, /* start byte mode */
		Rconmst = 1 << 10, /* master/slave mode */
		Rcontrx = 1 << 9,  /* transmitter/receiver mode */
		Rconxa  = 1 << 8,  /* expand address */
		Rconstp = 1 << 1,  /* stop condition */
		Rconstt = 1 << 0,  /* start condition */
	Roa      = 0x28,
	Rsa      = 0x2c,
	Rpsc     = 0x30,
	Rscll    = 0x34,
	Rsclh    = 0x38,
	Rsystest = 0x3c,
	Rbufstat = 0x40,
};

static Uint32
i2c_reg_read(Uint32 base, Uint8 r)
{
	volatile Uint32* reg = (Uint32*) (base + r);
	return *reg;
}

static void
i2c_reg_write(Uint32 base, Uint8 r, Uint32 value)
{
	volatile Uint32* reg = (Uint32*) (base + r);
	*reg = value;
}

static void
i2c_wait_for_bus(Uint32 base)
{
	while(i2c_reg_read(base, Rstat) & Rstatbb)
		;
}

static void
i2c_flush_fifo(Uint32 base)
{
	Uint16 stat;

	for(;;) {
		stat = i2c_reg_read(base, Rstat);
		if(stat == Rstatrrdy) {
			i2c_reg_read(base, Rdata);
			i2c_reg_write(base, Rstat, Rstatrrdy);
			timer_delay(PHYSTIMER2, 1000);
		} else {
			break;
		}
	}
}

static Uint32
i2c_wait_for_event(Uint32 base)
{
	int timeout;
	Uint32 status;

	timeout = 1000;
	do {
		status = i2c_reg_read(base, Rstat);
		timer_delay(PHYSTIMER2, 10);
	} while(status == 0 && timeout--);

	if(timeout <= 0) {
		console_puts("i2c: timeout waiting for event\n");
		i2c_reg_write(base, Rstat, 0xFFFF);
	}

	return status;
}

void
i2c_init(Uint32 base)
{
	if(i2c_reg_read(base, Rcon) & Rconen) {
		i2c_reg_write(base, Rcon, 0);
		timer_delay(PHYSTIMER2, 50000);
	}

	i2c_reg_write(base, Rsysc, 0x2);
	timer_delay(PHYSTIMER2, 1000);

	i2c_reg_write(base, Rcon, Rconen);
	while(!(i2c_reg_read(base, Rsyss) & 1))
		timer_delay(PHYSTIMER2, 1000);

	i2c_reg_write(base, Roa, 0x11);
	i2c_reg_write(base, Rie, Riexrdy
		| Rierrdy	
		| Rieardy
		| Rienack
		| Rieal);

	timer_delay(PHYSTIMER2, 1000);
	i2c_flush_fifo(base);
	i2c_reg_write(base, Rstat, 0xFFFF);
	i2c_reg_write(base, Rbuf, 0);
}

void
i2c_write(Uint32 base, Uint8 sa, Uint8 *data, Uint8 acnt, Uint8 dcnt)
{
	Uint32 status;
	Uint32 cnt;

	cnt = acnt + dcnt;

	i2c_wait_for_bus(base);
	i2c_reg_write(base, Rcnt, acnt + dcnt);
	i2c_reg_write(base, Rsa, sa);
	i2c_reg_write(base, Rcon, Rconen | Rconmst | Rcontrx | Rconstt | Rconstp);

	while(cnt) {
		status = i2c_wait_for_event(base);
		if(status == 0) {
			console_puts("i2c: status register was zero after event\n");
			goto error;
		}

		if(status & Rstatnack) {
			console_puts("i2c: got no acknowledgement\n");
			goto error;
		}

		if(status & Rstatxrdy) {
			i2c_reg_write(base, Rdata, *data++);
			i2c_reg_write(base, Rstat, Rstatxrdy);
			cnt--;
		} else {
			console_puts("i2c: was not ready to transmit\n");
			goto error;
		}
	}

	do {
		status = i2c_wait_for_event(base);
	} while(!(status & Rstatardy));

error:
	i2c_flush_fifo(base);
	i2c_reg_write(base, Rstat, 0xffff);
}

void i2c_read(Uint32 base, Uint8 sa, Uint8 *data, Uint8 acnt, Uint8 dcnt)
{
	Uint32 status;

	i2c_wait_for_bus(base);
	i2c_reg_write(base, Rcnt, acnt);
	i2c_reg_write(base, Rsa, sa);

	/* transmit mode if we need to send a register address */
	if(acnt)
		i2c_reg_write(base, Rcon, Rconen | Rconmst | Rcontrx | Rconstt | Rconstp);

	while(acnt) {
		status = i2c_wait_for_event(base);
		if(status == 0) {
			console_puts("i2c: status register was zero after event\n");
			goto error;
		}

		if(status & Rstatnack) {
			console_puts("i2c: got no acknowledgement\n");
			goto error;
		}

		if(status & Rstatxrdy) {
			acnt--;
			i2c_reg_write(base, Rdata, *data++);
			i2c_reg_write(base, Rstat, Rstatxrdy);
		} else {
			console_puts("i2c: was not ready to transmit\n");
			goto error;
		}

		if(status & Rstatardy) {
			/* address phase over, skip any remaining bytes */
			i2c_reg_write(base, Rstat, Rstatardy);
			if(acnt != 0)
				data += acnt;

			break;
		}
	}

	i2c_reg_write(base, Rcnt, dcnt);
	i2c_reg_write(base, Rsa, sa);
	i2c_reg_write(base, Rcon, Rconen | Rconmst | Rconstt | Rconstp);

	while(dcnt) {
		status = i2c_wait_for_event(base);
		if(status == 0) {
			console_puts("i2c: status register was zero after event\n");
			goto error;
		}

		if(status & Rstatnack) {
			console_puts("i2c: got no acknowledgement\n");
			goto error;
		}

		if(status & Rstatrrdy) {
			dcnt--;
			*data++ = i2c_reg_read(base, Rdata);
			i2c_reg_write(base, Rstat, Rstatxrdy);
		} else {
			console_puts("i2c: was not ready to transmit\n");
			goto error;
		}

		if(status & Rstatardy) {
			i2c_reg_write(base, Rstat, Rstatardy);
			break;
		}
	}

error:
	i2c_flush_fifo(base);
	i2c_reg_write(base, Rstat, 0xffff);
}