/*
* I2C read called by cmd_i2c when doing 'i2c read' and by cmd_eeprom.c
* Begin write, send address byte(s), begin read, receive data bytes, end.
*/
int i2c_read(u8 dev, uint addr, int alen, u8 *data, int length)
{
u32 status;
u32 i = 0;
u8 *cur_data = data;
/* Check the hardware can handle the requested bytes */
if ((length < 0) || (length > ZYNQ_I2C_TRANSFERT_SIZE_MAX))
return -EINVAL;
/* Write the register address */
setbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_CLR_FIFO |
ZYNQ_I2C_CONTROL_HOLD);
/*
* Temporarily disable restart (by clearing hold)
* It doesn't seem to work.
*/
clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_RW |
ZYNQ_I2C_CONTROL_HOLD);
writel(0xFF, &zynq_i2c->interrupt_status);
while (alen--)
writel(addr >> (8*alen), &zynq_i2c->data);
writel(dev, &zynq_i2c->address);
/* Wait for the address to be sent */
if (!zynq_i2c_wait(ZYNQ_I2C_INTERRUPT_COMP)) {
/* Release the bus */
clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);
return -ETIMEDOUT;
}
debug("Device acked address\n");
setbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_CLR_FIFO |
ZYNQ_I2C_CONTROL_RW);
/* Start reading data */
writel(dev, &zynq_i2c->address);
writel(length, &zynq_i2c->transfer_size);
/* Wait for data */
do {
status = zynq_i2c_wait(ZYNQ_I2C_INTERRUPT_COMP |
ZYNQ_I2C_INTERRUPT_DATA);
if (!status) {
/* Release the bus */
clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);
return -ETIMEDOUT;
}
debug("Read %d bytes\n",
length - readl(&zynq_i2c->transfer_size));
for (; i < length - readl(&zynq_i2c->transfer_size); i++)
*(cur_data++) = readl(&zynq_i2c->data);
} while (readl(&zynq_i2c->transfer_size) != 0);
/* All done... release the bus */
clrbits_le32(&zynq_i2c->control, ZYNQ_I2C_CONTROL_HOLD);
#ifdef DEBUG
zynq_i2c_debug_status();
#endif
return 0;
}
/* Wait for an interrupt */
static u32 zynq_i2c_wait(struct zynq_i2c_registers *zynq_i2c, u32 mask)
{
int timeout, int_status;
for (timeout = 0; timeout < 100; timeout++) {
udelay(100);
int_status = readl(&zynq_i2c->interrupt_status);
if (int_status & mask)
break;
}
#ifdef DEBUG
zynq_i2c_debug_status(zynq_i2c);
#endif
/* Clear interrupt status flags */
writel(int_status & mask, &zynq_i2c->interrupt_status);
return int_status & mask;
}
