--- /dev/null
+/*
+ * i2c.c - driver for Blackfin on-chip TWI/I2C
+ *
+ * Copyright (c) 2006-2010 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <common.h>
+#include <i2c.h>
+
+#include <asm/clock.h>
+#include <asm/twi.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 volatile 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)
+{
+ uint16_t int_stat;
+ ulong timebase = get_timer(0);
+
+ do {
+ int_stat = twi->int_stat;
+
+ if (int_stat & XMTSERV) {
+ debugi("processing XMTSERV");
+ twi->int_stat = XMTSERV;
+ SSYNC();
+ if (msg->alen) {
+ twi->xmt_data8 = *(msg->abuf++);
+ --msg->alen;
+ } else if (!(msg->flags & I2C_M_COMBO) && msg->len) {
+ twi->xmt_data8 = *(msg->buf++);
+ --msg->len;
+ } else {
+ twi->master_ctl |= (msg->flags & I2C_M_COMBO) ? RSTART | MDIR : STOP;
+ SSYNC();
+ }
+ }
+ if (int_stat & RCVSERV) {
+ debugi("processing RCVSERV");
+ twi->int_stat = RCVSERV;
+ SSYNC();
+ if (msg->len) {
+ *(msg->buf++) = twi->rcv_data8;
+ --msg->len;
+ } else if (msg->flags & I2C_M_STOP) {
+ twi->master_ctl |= STOP;
+ SSYNC();
+ }
+ }
+ if (int_stat & MERR) {
+ debugi("processing MERR");
+ twi->int_stat = MERR;
+ SSYNC();
+ return msg->len;
+ }
+ if (int_stat & MCOMP) {
+ debugi("processing MCOMP");
+ twi->int_stat = MCOMP;
+ SSYNC();
+ if (msg->flags & I2C_M_COMBO && msg->len) {
+ twi->master_ctl = (twi->master_ctl & ~RSTART) |
+ (min(msg->len, 0xff) << 6) | MEN | MDIR;
+ SSYNC();
+ } 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,
+ };
+ int ret;
+
+ dmemset(buffer, 0xff, len);
+ debugi("chip=0x%x addr=0x%02x alen=%i buf[0]=0x%02x len=%i flags=0x%02x[%s] ",
+ chip, addr, alen, buffer[0], len, flags, (flags & I2C_M_READ ? "rd" : "wr"));
+
+ /* wait for things to settle */
+ while (twi->master_stat & BUSBUSY)
+ if (ctrlc())
+ return 1;
+
+ /* Set Transmit device address */
+ twi->master_addr = chip;
+
+ /* Clear the FIFO before starting things */
+ twi->fifo_ctl = XMTFLUSH | RCVFLUSH;
+ SSYNC();
+ twi->fifo_ctl = 0;
+ SSYNC();
+
+ /* prime the pump */
+ if (msg.alen) {
+ len = (msg.flags & I2C_M_COMBO) ? msg.alen : msg.alen + len;
+ debugi("first byte=0x%02x", *msg.abuf);
+ twi->xmt_data8 = *(msg.abuf++);
+ --msg.alen;
+ } else if (!(msg.flags & I2C_M_READ) && msg.len) {
+ debugi("first byte=0x%02x", *msg.buf);
+ twi->xmt_data8 = *(msg.buf++);
+ --msg.len;
+ }
+
+ /* clear int stat */
+ twi->master_stat = -1;
+ twi->int_stat = -1;
+ twi->int_mask = 0;
+ SSYNC();
+
+ /* Master enable */
+ twi->master_ctl =
+ (twi->master_ctl & FAST) |
+ (min(len, 0xff) << 6) | MEN |
+ ((msg.flags & I2C_M_READ) ? MDIR : 0);
+ SSYNC();
+ debugi("CTL=0x%04x", twi->master_ctl);
+
+ /* process the rest */
+ ret = wait_for_completion(&msg);
+ debugi("ret=%d", ret);
+
+ if (ret) {
+ twi->master_ctl &= ~MEN;
+ twi->control &= ~TWI_ENA;
+ SSYNC();
+ twi->control |= TWI_ENA;
+ SSYNC();
+ }
+
+ return ret;
+}
+
+/**
+ * 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;
+ twi->clkdiv = (clkdiv << 8) | (clkdiv & 0xff);
+
+ /* Don't turn it on */
+ twi->master_ctl = (speed > 100000 ? FAST : 0);
+
+ return 0;
+}
+
+/**
+ * i2c_get_bus_speed - get i2c bus speed
+ * @speed: bus speed (in HZ)
+ */
+unsigned int i2c_get_bus_speed(void)
+{
+ /* 10 MHz / (2 * CLKDIV) -> 5 MHz / CLKDIV */
+ return 5000000 / (twi->clkdiv & 0xff);
+}
+
+/**
+ * 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 */
+ twi->control = prescale;
+
+ /* Set TWI interface clock as specified */
+ i2c_set_bus_speed(speed);
+
+ /* Enable it */
+ twi->control = TWI_ENA | prescale;
+ SSYNC();
+
+ debugi("CONTROL:0x%04x CLKDIV:0x%04x", twi->control, twi->clkdiv);
+
+#if CONFIG_SYS_I2C_SLAVE
+# error I2C slave support not tested/supported
+ /* If they want us as a slave, do it */
+ if (slaveaddr) {
+ twi->slave_addr = slaveaddr;
+ twi->slave_ctl = SEN;
+ }
+#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;
+#endif
+ 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;
+#endif
+ default: return -1;
+ }
+}
projects / u-boot.git / commitdiff