diff options
Diffstat (limited to 'drivers/i2c/bfin-twi_i2c.c')
| -rw-r--r-- | drivers/i2c/bfin-twi_i2c.c | 285 |
1 files changed, 285 insertions, 0 deletions
diff --git a/drivers/i2c/bfin-twi_i2c.c b/drivers/i2c/bfin-twi_i2c.c new file mode 100644 index 0000000..cfe55cd --- /dev/null +++ b/drivers/i2c/bfin-twi_i2c.c @@ -0,0 +1,285 @@ +/* + * i2c.c - driver for Blackfin on-chip TWI/I2C + * + * Copyright (c) 2006-2008 Analog Devices Inc. + * + * Licensed under the GPL-2 or later. + */ + +#include <common.h> +#include <i2c.h> + +#include <asm/blackfin.h> +#include <asm/mach-common/bits/twi.h> + +#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", \ + bfin_read_TWI_MASTER_STAT(), bfin_read_TWI_FIFO_STAT(), bfin_read_TWI_INT_STAT(), \ + __func__, __LINE__, ## args) + +#ifdef TWI0_CLKDIV +#define bfin_write_TWI_CLKDIV(val) bfin_write_TWI0_CLKDIV(val) +#define bfin_write_TWI_CONTROL(val) bfin_write_TWI0_CONTROL(val) +#define bfin_read_TWI_CONTROL(val) bfin_read_TWI0_CONTROL(val) +#define bfin_write_TWI_MASTER_ADDR(val) bfin_write_TWI0_MASTER_ADDR(val) +#define bfin_write_TWI_XMT_DATA8(val) bfin_write_TWI0_XMT_DATA8(val) +#define bfin_read_TWI_RCV_DATA8() bfin_read_TWI0_RCV_DATA8() +#define bfin_read_TWI_INT_STAT() bfin_read_TWI0_INT_STAT() +#define bfin_write_TWI_INT_STAT(val) bfin_write_TWI0_INT_STAT(val) +#define bfin_read_TWI_MASTER_STAT() bfin_read_TWI0_MASTER_STAT() +#define bfin_write_TWI_MASTER_STAT(val) bfin_write_TWI0_MASTER_STAT(val) +#define bfin_read_TWI_MASTER_CTL() bfin_read_TWI0_MASTER_CTL() +#define bfin_write_TWI_MASTER_CTL(val) bfin_write_TWI0_MASTER_CTL(val) +#define bfin_write_TWI_INT_MASK(val) bfin_write_TWI0_INT_MASK(val) +#define bfin_write_TWI_FIFO_CTL(val) bfin_write_TWI0_FIFO_CTL(val) +#endif + +#ifdef CONFIG_TWICLK_KHZ +# error do not define CONFIG_TWICLK_KHZ ... use CONFIG_SYS_I2C_SPEED +#endif +#if CONFIG_SYS_I2C_SPEED > 400000 +# error The Blackfin I2C hardware can only operate at 400KHz max +#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 */ +}; + +/** + * 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; + + while (!ctrlc()) { + int_stat = bfin_read_TWI_INT_STAT(); + + if (int_stat & XMTSERV) { + debugi("processing XMTSERV"); + bfin_write_TWI_INT_STAT(XMTSERV); + SSYNC(); + if (msg->alen) { + bfin_write_TWI_XMT_DATA8(*(msg->abuf++)); + --msg->alen; + } else if (!(msg->flags & I2C_M_COMBO) && msg->len) { + bfin_write_TWI_XMT_DATA8(*(msg->buf++)); + --msg->len; + } else { + bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL() | + (msg->flags & I2C_M_COMBO ? RSTART | MDIR : STOP)); + SSYNC(); + } + } + if (int_stat & RCVSERV) { + debugi("processing RCVSERV"); + bfin_write_TWI_INT_STAT(RCVSERV); + SSYNC(); + if (msg->len) { + *(msg->buf++) = bfin_read_TWI_RCV_DATA8(); + --msg->len; + } else if (msg->flags & I2C_M_STOP) { + bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL() | STOP); + SSYNC(); + } + } + if (int_stat & MERR) { + debugi("processing MERR"); + bfin_write_TWI_INT_STAT(MERR); + SSYNC(); + break; + } + if (int_stat & MCOMP) { + debugi("processing MCOMP"); + bfin_write_TWI_INT_STAT(MCOMP); + SSYNC(); + if (msg->flags & I2C_M_COMBO && msg->len) { + bfin_write_TWI_MASTER_CTL((bfin_read_TWI_MASTER_CTL() & ~RSTART) | + (min(msg->len, 0xff) << 6) | MEN | MDIR); + SSYNC(); + } else + break; + } + } + + 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 (bfin_read_TWI_MASTER_STAT() & BUSBUSY) + if (ctrlc()) + return 1; + + /* Set Transmit device address */ + bfin_write_TWI_MASTER_ADDR(chip); + + /* Clear the FIFO before starting things */ + bfin_write_TWI_FIFO_CTL(XMTFLUSH | RCVFLUSH); + SSYNC(); + bfin_write_TWI_FIFO_CTL(0); + SSYNC(); + + /* prime the pump */ + if (msg.alen) { + len = msg.alen; + debugi("first byte=0x%02x", *msg.abuf); + bfin_write_TWI_XMT_DATA8(*(msg.abuf++)); + --msg.alen; + } else if (!(msg.flags & I2C_M_READ) && msg.len) { + debugi("first byte=0x%02x", *msg.buf); + bfin_write_TWI_XMT_DATA8(*(msg.buf++)); + --msg.len; + } + + /* clear int stat */ + bfin_write_TWI_MASTER_STAT(-1); + bfin_write_TWI_INT_STAT(-1); + bfin_write_TWI_INT_MASK(0); + SSYNC(); + + /* Master enable */ + bfin_write_TWI_MASTER_CTL( + (bfin_read_TWI_MASTER_CTL() & FAST) | + (min(len, 0xff) << 6) | MEN | + ((msg.flags & I2C_M_READ) ? MDIR : 0) + ); + SSYNC(); + debugi("CTL=0x%04x", bfin_read_TWI_MASTER_CTL()); + + /* process the rest */ + ret = wait_for_completion(&msg); + debugi("ret=%d", ret); + + if (ret) { + bfin_write_TWI_MASTER_CTL(bfin_read_TWI_MASTER_CTL() & ~MEN); + bfin_write_TWI_CONTROL(bfin_read_TWI_CONTROL() & ~TWI_ENA); + SSYNC(); + bfin_write_TWI_CONTROL(bfin_read_TWI_CONTROL() | TWI_ENA); + SSYNC(); + } + + return ret; +} + +/* + * 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_sclk() / 1024 / 1024 + 5) / 10) & 0x7F; + + /* Set TWI internal clock as 10MHz */ + bfin_write_TWI_CONTROL(prescale); + + /* Set TWI interface clock as specified */ + bfin_write_TWI_CLKDIV( + ((5 * 1024 / (speed / 1000)) << 8) | + ((5 * 1024 / (speed / 1000)) & 0xFF) + ); + + /* Don't turn it on */ + bfin_write_TWI_MASTER_CTL(speed > 100000 ? FAST : 0); + + /* But enable it */ + bfin_write_TWI_CONTROL(TWI_ENA | prescale); + SSYNC(); + + debugi("CONTROL:0x%04x CLKDIV:0x%04x", + bfin_read_TWI_CONTROL(), bfin_read_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) { + bfin_write_TWI_SLAVE_ADDR(slaveaddr); + bfin_write_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 to store data read from 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); +} |