diff options
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/i2c-at91.c | 121 |
1 files changed, 101 insertions, 20 deletions
diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c index 0e88b68bb519..817ae69cd1fb 100644 --- a/drivers/i2c/busses/i2c-at91.c +++ b/drivers/i2c/busses/i2c-at91.c @@ -49,6 +49,11 @@ #define AT91_TWI_SVDIS BIT(5) /* Slave Transfer Disable */ #define AT91_TWI_QUICK BIT(6) /* SMBus quick command */ #define AT91_TWI_SWRST BIT(7) /* Software Reset */ +#define AT91_TWI_ACMEN BIT(16) /* Alternative Command Mode Enable */ +#define AT91_TWI_ACMDIS BIT(17) /* Alternative Command Mode Disable */ +#define AT91_TWI_THRCLR BIT(24) /* Transmit Holding Register Clear */ +#define AT91_TWI_RHRCLR BIT(25) /* Receive Holding Register Clear */ +#define AT91_TWI_LOCKCLR BIT(26) /* Lock Clear */ #define AT91_TWI_MMR 0x0004 /* Master Mode Register */ #define AT91_TWI_IADRSZ_1 0x0100 /* Internal Device Address Size */ @@ -65,6 +70,7 @@ #define AT91_TWI_OVRE BIT(6) /* Overrun Error */ #define AT91_TWI_UNRE BIT(7) /* Underrun Error */ #define AT91_TWI_NACK BIT(8) /* Not Acknowledged */ +#define AT91_TWI_LOCK BIT(23) /* TWI Lock due to Frame Errors */ #define AT91_TWI_INT_MASK \ (AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK) @@ -75,10 +81,15 @@ #define AT91_TWI_RHR 0x0030 /* Receive Holding Register */ #define AT91_TWI_THR 0x0034 /* Transmit Holding Register */ +#define AT91_TWI_ACR 0x0040 /* Alternative Command Register */ +#define AT91_TWI_ACR_DATAL(len) ((len) & 0xff) +#define AT91_TWI_ACR_DIR BIT(8) + struct at91_twi_pdata { unsigned clk_max_div; unsigned clk_offset; bool has_unre_flag; + bool has_alt_cmd; struct at_dma_slave dma_slave; }; @@ -204,7 +215,8 @@ static void at91_twi_write_next_byte(struct at91_twi_dev *dev) /* send stop when last byte has been written */ if (--dev->buf_len == 0) - at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP); + if (!dev->pdata->has_alt_cmd) + at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP); dev_dbg(dev->dev, "wrote 0x%x, to go %d\n", *dev->buf, dev->buf_len); @@ -226,7 +238,8 @@ static void at91_twi_write_data_dma_callback(void *data) * we just have to enable TXCOMP one. */ at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP); - at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP); + if (!dev->pdata->has_alt_cmd) + at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP); } static void at91_twi_write_data_dma(struct at91_twi_dev *dev) @@ -302,7 +315,7 @@ static void at91_twi_read_next_byte(struct at91_twi_dev *dev) } /* send stop if second but last byte has been read */ - if (dev->buf_len == 1) + if (!dev->pdata->has_alt_cmd && dev->buf_len == 1) at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP); dev_dbg(dev->dev, "read 0x%x, to go %d\n", *dev->buf, dev->buf_len); @@ -313,14 +326,18 @@ static void at91_twi_read_next_byte(struct at91_twi_dev *dev) static void at91_twi_read_data_dma_callback(void *data) { struct at91_twi_dev *dev = (struct at91_twi_dev *)data; + unsigned ier = AT91_TWI_TXCOMP; dma_unmap_single(dev->dev, sg_dma_address(&dev->dma.sg), dev->buf_len, DMA_FROM_DEVICE); - /* The last two bytes have to be read without using dma */ - dev->buf += dev->buf_len - 2; - dev->buf_len = 2; - at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_RXRDY | AT91_TWI_TXCOMP); + if (!dev->pdata->has_alt_cmd) { + /* The last two bytes have to be read without using dma */ + dev->buf += dev->buf_len - 2; + dev->buf_len = 2; + ier |= AT91_TWI_RXRDY; + } + at91_twi_write(dev, AT91_TWI_IER, ier); } static void at91_twi_read_data_dma(struct at91_twi_dev *dev) @@ -329,13 +346,14 @@ static void at91_twi_read_data_dma(struct at91_twi_dev *dev) struct dma_async_tx_descriptor *rxdesc; struct at91_twi_dma *dma = &dev->dma; struct dma_chan *chan_rx = dma->chan_rx; + size_t buf_len; + buf_len = (dev->pdata->has_alt_cmd) ? dev->buf_len : dev->buf_len - 2; dma->direction = DMA_FROM_DEVICE; /* Keep in mind that we won't use dma to read the last two bytes */ at91_twi_irq_save(dev); - dma_addr = dma_map_single(dev->dev, dev->buf, dev->buf_len - 2, - DMA_FROM_DEVICE); + dma_addr = dma_map_single(dev->dev, dev->buf, buf_len, DMA_FROM_DEVICE); if (dma_mapping_error(dev->dev, dma_addr)) { dev_err(dev->dev, "dma map failed\n"); return; @@ -343,7 +361,7 @@ static void at91_twi_read_data_dma(struct at91_twi_dev *dev) dma->buf_mapped = true; at91_twi_irq_restore(dev); dma->sg.dma_address = dma_addr; - sg_dma_len(&dma->sg) = dev->buf_len - 2; + sg_dma_len(&dma->sg) = buf_len; rxdesc = dmaengine_prep_slave_sg(chan_rx, &dma->sg, 1, DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT | DMA_CTRL_ACK); @@ -394,6 +412,7 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) int ret; unsigned long time_left; bool has_unre_flag = dev->pdata->has_unre_flag; + bool has_alt_cmd = dev->pdata->has_alt_cmd; /* * WARNING: the TXCOMP bit in the Status Register is NOT a clear on @@ -403,6 +422,21 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) * empty and STOP condition has been sent. * Consequently, we should enable NACK interrupt rather than TXCOMP to * detect transmission failure. + * Indeed let's take the case of an i2c write command using DMA. + * Whenever the slave doesn't acknowledge a byte, the LOCK, NACK and + * TXCOMP bits are set together into the Status Register. + * LOCK is a clear on write bit, which is set to prevent the DMA + * controller from sending new data on the i2c bus after a NACK + * condition has happened. Once locked, this i2c peripheral stops + * triggering the DMA controller for new data but it is more than + * likely that a new DMA transaction is already in progress, writing + * into the Transmit Holding Register. Since the peripheral is locked, + * these new data won't be sent to the i2c bus but they will remain + * into the Transmit Holding Register, so TXCOMP bit is cleared. + * Then when the interrupt handler is called, the Status Register is + * read: the TXCOMP bit is clear but NACK bit is still set. The driver + * manage the error properly, without waiting for timeout. + * This case can be reproduced easyly when writing into an at24 eeprom. * * Besides, the TXCOMP bit is already set before the i2c transaction * has been started. For read transactions, this bit is cleared when @@ -418,9 +452,9 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) * condition since we don't know whether the TXCOMP interrupt is enabled * before or after the DMA has started to write into THR. So the TXCOMP * interrupt is enabled later by at91_twi_write_data_dma_callback(). - * Immediately after in that DMA callback, we still need to send the - * STOP condition manually writing the corresponding bit into the - * Control Register. + * Immediately after in that DMA callback, if the alternative command + * mode is not used, we still need to send the STOP condition manually + * writing the corresponding bit into the Control Register. */ dev_dbg(dev->dev, "transfer: %s %d bytes.\n", @@ -441,14 +475,16 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) } /* if only one byte is to be read, immediately stop transfer */ - if (dev->buf_len <= 1 && !(dev->msg->flags & I2C_M_RECV_LEN)) + if (!has_alt_cmd && dev->buf_len <= 1 && + !(dev->msg->flags & I2C_M_RECV_LEN)) start_flags |= AT91_TWI_STOP; at91_twi_write(dev, AT91_TWI_CR, start_flags); /* - * When using dma, the last byte has to be read manually in - * order to not send the stop command too late and then - * to receive extra data. In practice, there are some issues - * if you use the dma to read n-1 bytes because of latency. + * When using dma without alternative command mode, the last + * byte has to be read manually in order to not send the stop + * command too late and then to receive extra data. + * In practice, there are some issues if you use the dma to + * read n-1 bytes because of latency. * Reading n-2 bytes with dma and the two last ones manually * seems to be the best solution. */ @@ -477,6 +513,7 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) time_left = wait_for_completion_timeout(&dev->cmd_complete, dev->adapter.timeout); if (time_left == 0) { + dev->transfer_status |= at91_twi_read(dev, AT91_TWI_SR); dev_err(dev->dev, "controller timed out\n"); at91_init_twi_bus(dev); ret = -ETIMEDOUT; @@ -497,6 +534,11 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) ret = -EIO; goto error; } + if (has_alt_cmd && (dev->transfer_status & AT91_TWI_LOCK)) { + dev_err(dev->dev, "tx locked\n"); + ret = -EIO; + goto error; + } if (dev->recv_len_abort) { dev_err(dev->dev, "invalid smbus block length recvd\n"); ret = -EPROTO; @@ -508,7 +550,14 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) return 0; error: + /* first stop DMA transfer if still in progress */ at91_twi_dma_cleanup(dev); + /* then flush THR/FIFO and unlock TX if locked */ + if (has_alt_cmd && (dev->transfer_status & AT91_TWI_LOCK)) { + dev_dbg(dev->dev, "unlock tx\n"); + at91_twi_write(dev, AT91_TWI_CR, + AT91_TWI_THRCLR | AT91_TWI_LOCKCLR); + } return ret; } @@ -518,6 +567,7 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num) int ret; unsigned int_addr_flag = 0; struct i2c_msg *m_start = msg; + bool is_read, use_alt_cmd = false; dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num); @@ -540,8 +590,23 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num) at91_twi_write(dev, AT91_TWI_IADR, internal_address); } - at91_twi_write(dev, AT91_TWI_MMR, (m_start->addr << 16) | int_addr_flag - | ((m_start->flags & I2C_M_RD) ? AT91_TWI_MREAD : 0)); + is_read = (m_start->flags & I2C_M_RD); + if (dev->pdata->has_alt_cmd) { + if (m_start->len > 0) { + at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_ACMEN); + at91_twi_write(dev, AT91_TWI_ACR, + AT91_TWI_ACR_DATAL(m_start->len) | + ((is_read) ? AT91_TWI_ACR_DIR : 0)); + use_alt_cmd = true; + } else { + at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_ACMDIS); + } + } + + at91_twi_write(dev, AT91_TWI_MMR, + (m_start->addr << 16) | + int_addr_flag | + ((!use_alt_cmd && is_read) ? AT91_TWI_MREAD : 0)); dev->buf_len = m_start->len; dev->buf = m_start->buf; @@ -582,30 +647,35 @@ static struct at91_twi_pdata at91rm9200_config = { .clk_max_div = 5, .clk_offset = 3, .has_unre_flag = true, + .has_alt_cmd = false, }; static struct at91_twi_pdata at91sam9261_config = { .clk_max_div = 5, .clk_offset = 4, .has_unre_flag = false, + .has_alt_cmd = false, }; static struct at91_twi_pdata at91sam9260_config = { .clk_max_div = 7, .clk_offset = 4, .has_unre_flag = false, + .has_alt_cmd = false, }; static struct at91_twi_pdata at91sam9g20_config = { .clk_max_div = 7, .clk_offset = 4, .has_unre_flag = false, + .has_alt_cmd = false, }; static struct at91_twi_pdata at91sam9g10_config = { .clk_max_div = 7, .clk_offset = 4, .has_unre_flag = false, + .has_alt_cmd = false, }; static const struct platform_device_id at91_twi_devtypes[] = { @@ -634,6 +704,14 @@ static struct at91_twi_pdata at91sam9x5_config = { .clk_max_div = 7, .clk_offset = 4, .has_unre_flag = false, + .has_alt_cmd = false, +}; + +static struct at91_twi_pdata sama5d2_config = { + .clk_max_div = 7, + .clk_offset = 4, + .has_unre_flag = true, + .has_alt_cmd = true, }; static const struct of_device_id atmel_twi_dt_ids[] = { @@ -656,6 +734,9 @@ static const struct of_device_id atmel_twi_dt_ids[] = { .compatible = "atmel,at91sam9x5-i2c", .data = &at91sam9x5_config, }, { + .compatible = "atmel,sama5d2-i2c", + .data = &sama5d2_config, + }, { /* sentinel */ } }; |
