diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-at91-master.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-at91-master.c | 801 |
1 files changed, 801 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-at91-master.c b/drivers/i2c/busses/i2c-at91-master.c new file mode 100644 index 000000000000..e87232f2e708 --- /dev/null +++ b/drivers/i2c/busses/i2c-at91-master.c @@ -0,0 +1,801 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * i2c Support for Atmel's AT91 Two-Wire Interface (TWI) + * + * Copyright (C) 2011 Weinmann Medical GmbH + * Author: Nikolaus Voss <n.voss@weinmann.de> + * + * Evolved from original work by: + * Copyright (C) 2004 Rick Bronson + * Converted to 2.6 by Andrew Victor <andrew@sanpeople.com> + * + * Borrowed heavily from original work by: + * Copyright (C) 2000 Philip Edelbrock <phil@stimpy.netroedge.com> + */ + +#include <linux/clk.h> +#include <linux/completion.h> +#include <linux/dma-mapping.h> +#include <linux/dmaengine.h> +#include <linux/err.h> +#include <linux/i2c.h> +#include <linux/interrupt.h> +#include <linux/io.h> +#include <linux/of.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> +#include <linux/platform_data/dma-atmel.h> +#include <linux/pm_runtime.h> + +#include "i2c-at91.h" + +void at91_init_twi_bus_master(struct at91_twi_dev *dev) +{ + /* FIFO should be enabled immediately after the software reset */ + if (dev->fifo_size) + at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_FIFOEN); + at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_MSEN); + at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SVDIS); + at91_twi_write(dev, AT91_TWI_CWGR, dev->twi_cwgr_reg); +} + +/* + * Calculate symmetric clock as stated in datasheet: + * twi_clk = F_MAIN / (2 * (cdiv * (1 << ckdiv) + offset)) + */ +static void at91_calc_twi_clock(struct at91_twi_dev *dev) +{ + int ckdiv, cdiv, div, hold = 0; + struct at91_twi_pdata *pdata = dev->pdata; + int offset = pdata->clk_offset; + int max_ckdiv = pdata->clk_max_div; + struct i2c_timings timings, *t = &timings; + + i2c_parse_fw_timings(dev->dev, t, true); + + div = max(0, (int)DIV_ROUND_UP(clk_get_rate(dev->clk), + 2 * t->bus_freq_hz) - offset); + ckdiv = fls(div >> 8); + cdiv = div >> ckdiv; + + if (ckdiv > max_ckdiv) { + dev_warn(dev->dev, "%d exceeds ckdiv max value which is %d.\n", + ckdiv, max_ckdiv); + ckdiv = max_ckdiv; + cdiv = 255; + } + + if (pdata->has_hold_field) { + /* + * hold time = HOLD + 3 x T_peripheral_clock + * Use clk rate in kHz to prevent overflows when computing + * hold. + */ + hold = DIV_ROUND_UP(t->sda_hold_ns + * (clk_get_rate(dev->clk) / 1000), 1000000); + hold -= 3; + if (hold < 0) + hold = 0; + if (hold > AT91_TWI_CWGR_HOLD_MAX) { + dev_warn(dev->dev, + "HOLD field set to its maximum value (%d instead of %d)\n", + AT91_TWI_CWGR_HOLD_MAX, hold); + hold = AT91_TWI_CWGR_HOLD_MAX; + } + } + + dev->twi_cwgr_reg = (ckdiv << 16) | (cdiv << 8) | cdiv + | AT91_TWI_CWGR_HOLD(hold); + + dev_dbg(dev->dev, "cdiv %d ckdiv %d hold %d (%d ns)\n", + cdiv, ckdiv, hold, t->sda_hold_ns); +} + +static void at91_twi_dma_cleanup(struct at91_twi_dev *dev) +{ + struct at91_twi_dma *dma = &dev->dma; + + at91_twi_irq_save(dev); + + if (dma->xfer_in_progress) { + if (dma->direction == DMA_FROM_DEVICE) + dmaengine_terminate_all(dma->chan_rx); + else + dmaengine_terminate_all(dma->chan_tx); + dma->xfer_in_progress = false; + } + if (dma->buf_mapped) { + dma_unmap_single(dev->dev, sg_dma_address(&dma->sg[0]), + dev->buf_len, dma->direction); + dma->buf_mapped = false; + } + + at91_twi_irq_restore(dev); +} + +static void at91_twi_write_next_byte(struct at91_twi_dev *dev) +{ + if (!dev->buf_len) + return; + + /* 8bit write works with and without FIFO */ + writeb_relaxed(*dev->buf, dev->base + AT91_TWI_THR); + + /* send stop when last byte has been written */ + if (--dev->buf_len == 0) + if (!dev->use_alt_cmd) + at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP); + + dev_dbg(dev->dev, "wrote 0x%x, to go %zu\n", *dev->buf, dev->buf_len); + + ++dev->buf; +} + +static void at91_twi_write_data_dma_callback(void *data) +{ + struct at91_twi_dev *dev = (struct at91_twi_dev *)data; + + dma_unmap_single(dev->dev, sg_dma_address(&dev->dma.sg[0]), + dev->buf_len, DMA_TO_DEVICE); + + /* + * When this callback is called, THR/TX FIFO is likely not to be empty + * yet. So we have to wait for TXCOMP or NACK bits to be set into the + * Status Register to be sure that the STOP bit has been sent and the + * transfer is completed. The NACK interrupt has already been enabled, + * we just have to enable TXCOMP one. + */ + at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP); + if (!dev->use_alt_cmd) + at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP); +} + +static void at91_twi_write_data_dma(struct at91_twi_dev *dev) +{ + dma_addr_t dma_addr; + struct dma_async_tx_descriptor *txdesc; + struct at91_twi_dma *dma = &dev->dma; + struct dma_chan *chan_tx = dma->chan_tx; + unsigned int sg_len = 1; + + if (!dev->buf_len) + return; + + dma->direction = DMA_TO_DEVICE; + + at91_twi_irq_save(dev); + dma_addr = dma_map_single(dev->dev, dev->buf, dev->buf_len, + DMA_TO_DEVICE); + if (dma_mapping_error(dev->dev, dma_addr)) { + dev_err(dev->dev, "dma map failed\n"); + return; + } + dma->buf_mapped = true; + at91_twi_irq_restore(dev); + + if (dev->fifo_size) { + size_t part1_len, part2_len; + struct scatterlist *sg; + unsigned fifo_mr; + + sg_len = 0; + + part1_len = dev->buf_len & ~0x3; + if (part1_len) { + sg = &dma->sg[sg_len++]; + sg_dma_len(sg) = part1_len; + sg_dma_address(sg) = dma_addr; + } + + part2_len = dev->buf_len & 0x3; + if (part2_len) { + sg = &dma->sg[sg_len++]; + sg_dma_len(sg) = part2_len; + sg_dma_address(sg) = dma_addr + part1_len; + } + + /* + * DMA controller is triggered when at least 4 data can be + * written into the TX FIFO + */ + fifo_mr = at91_twi_read(dev, AT91_TWI_FMR); + fifo_mr &= ~AT91_TWI_FMR_TXRDYM_MASK; + fifo_mr |= AT91_TWI_FMR_TXRDYM(AT91_TWI_FOUR_DATA); + at91_twi_write(dev, AT91_TWI_FMR, fifo_mr); + } else { + sg_dma_len(&dma->sg[0]) = dev->buf_len; + sg_dma_address(&dma->sg[0]) = dma_addr; + } + + txdesc = dmaengine_prep_slave_sg(chan_tx, dma->sg, sg_len, + DMA_MEM_TO_DEV, + DMA_PREP_INTERRUPT | DMA_CTRL_ACK); + if (!txdesc) { + dev_err(dev->dev, "dma prep slave sg failed\n"); + goto error; + } + + txdesc->callback = at91_twi_write_data_dma_callback; + txdesc->callback_param = dev; + + dma->xfer_in_progress = true; + dmaengine_submit(txdesc); + dma_async_issue_pending(chan_tx); + + return; + +error: + at91_twi_dma_cleanup(dev); +} + +static void at91_twi_read_next_byte(struct at91_twi_dev *dev) +{ + /* + * If we are in this case, it means there is garbage data in RHR, so + * delete them. + */ + if (!dev->buf_len) { + at91_twi_read(dev, AT91_TWI_RHR); + return; + } + + /* 8bit read works with and without FIFO */ + *dev->buf = readb_relaxed(dev->base + AT91_TWI_RHR); + --dev->buf_len; + + /* return if aborting, we only needed to read RHR to clear RXRDY*/ + if (dev->recv_len_abort) + return; + + /* handle I2C_SMBUS_BLOCK_DATA */ + if (unlikely(dev->msg->flags & I2C_M_RECV_LEN)) { + /* ensure length byte is a valid value */ + if (*dev->buf <= I2C_SMBUS_BLOCK_MAX && *dev->buf > 0) { + dev->msg->flags &= ~I2C_M_RECV_LEN; + dev->buf_len += *dev->buf; + dev->msg->len = dev->buf_len + 1; + dev_dbg(dev->dev, "received block length %zu\n", + dev->buf_len); + } else { + /* abort and send the stop by reading one more byte */ + dev->recv_len_abort = true; + dev->buf_len = 1; + } + } + + /* send stop if second but last byte has been read */ + if (!dev->use_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 %zu\n", *dev->buf, dev->buf_len); + + ++dev->buf; +} + +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[0]), + dev->buf_len, DMA_FROM_DEVICE); + + if (!dev->use_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) +{ + dma_addr_t dma_addr; + 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->use_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, buf_len, DMA_FROM_DEVICE); + if (dma_mapping_error(dev->dev, dma_addr)) { + dev_err(dev->dev, "dma map failed\n"); + return; + } + dma->buf_mapped = true; + at91_twi_irq_restore(dev); + + if (dev->fifo_size && IS_ALIGNED(buf_len, 4)) { + unsigned fifo_mr; + + /* + * DMA controller is triggered when at least 4 data can be + * read from the RX FIFO + */ + fifo_mr = at91_twi_read(dev, AT91_TWI_FMR); + fifo_mr &= ~AT91_TWI_FMR_RXRDYM_MASK; + fifo_mr |= AT91_TWI_FMR_RXRDYM(AT91_TWI_FOUR_DATA); + at91_twi_write(dev, AT91_TWI_FMR, fifo_mr); + } + + sg_dma_len(&dma->sg[0]) = buf_len; + sg_dma_address(&dma->sg[0]) = dma_addr; + + rxdesc = dmaengine_prep_slave_sg(chan_rx, dma->sg, 1, DMA_DEV_TO_MEM, + DMA_PREP_INTERRUPT | DMA_CTRL_ACK); + if (!rxdesc) { + dev_err(dev->dev, "dma prep slave sg failed\n"); + goto error; + } + + rxdesc->callback = at91_twi_read_data_dma_callback; + rxdesc->callback_param = dev; + + dma->xfer_in_progress = true; + dmaengine_submit(rxdesc); + dma_async_issue_pending(dma->chan_rx); + + return; + +error: + at91_twi_dma_cleanup(dev); +} + +static irqreturn_t atmel_twi_interrupt(int irq, void *dev_id) +{ + struct at91_twi_dev *dev = dev_id; + const unsigned status = at91_twi_read(dev, AT91_TWI_SR); + const unsigned irqstatus = status & at91_twi_read(dev, AT91_TWI_IMR); + + if (!irqstatus) + return IRQ_NONE; + /* + * In reception, the behavior of the twi device (before sama5d2) is + * weird. There is some magic about RXRDY flag! When a data has been + * almost received, the reception of a new one is anticipated if there + * is no stop command to send. That is the reason why ask for sending + * the stop command not on the last data but on the second last one. + * + * Unfortunately, we could still have the RXRDY flag set even if the + * transfer is done and we have read the last data. It might happen + * when the i2c slave device sends too quickly data after receiving the + * ack from the master. The data has been almost received before having + * the order to send stop. In this case, sending the stop command could + * cause a RXRDY interrupt with a TXCOMP one. It is better to manage + * the RXRDY interrupt first in order to not keep garbage data in the + * Receive Holding Register for the next transfer. + */ + if (irqstatus & AT91_TWI_RXRDY) { + /* + * Read all available bytes at once by polling RXRDY usable w/ + * and w/o FIFO. With FIFO enabled we could also read RXFL and + * avoid polling RXRDY. + */ + do { + at91_twi_read_next_byte(dev); + } while (at91_twi_read(dev, AT91_TWI_SR) & AT91_TWI_RXRDY); + } + + /* + * When a NACK condition is detected, the I2C controller sets the NACK, + * TXCOMP and TXRDY bits all together in the Status Register (SR). + * + * 1 - Handling NACK errors with CPU write transfer. + * + * In such case, we should not write the next byte into the Transmit + * Holding Register (THR) otherwise the I2C controller would start a new + * transfer and the I2C slave is likely to reply by another NACK. + * + * 2 - Handling NACK errors with DMA write transfer. + * + * By setting the TXRDY bit in the SR, the I2C controller also triggers + * the DMA controller to write the next data into the THR. Then the + * result depends on the hardware version of the I2C controller. + * + * 2a - Without support of the Alternative Command mode. + * + * This is the worst case: the DMA controller is triggered to write the + * next data into the THR, hence starting a new transfer: the I2C slave + * is likely to reply by another NACK. + * Concurrently, this interrupt handler is likely to be called to manage + * the first NACK before the I2C controller detects the second NACK and + * sets once again the NACK bit into the SR. + * When handling the first NACK, this interrupt handler disables the I2C + * controller interruptions, especially the NACK interrupt. + * Hence, the NACK bit is pending into the SR. This is why we should + * read the SR to clear all pending interrupts at the beginning of + * at91_do_twi_transfer() before actually starting a new transfer. + * + * 2b - With support of the Alternative Command mode. + * + * When a NACK condition is detected, the I2C controller also locks the + * THR (and sets the LOCK bit in the SR): even though the DMA controller + * is triggered by the TXRDY bit to write the next data into the THR, + * this data actually won't go on the I2C bus hence a second NACK is not + * generated. + */ + if (irqstatus & (AT91_TWI_TXCOMP | AT91_TWI_NACK)) { + at91_disable_twi_interrupts(dev); + complete(&dev->cmd_complete); + } else if (irqstatus & AT91_TWI_TXRDY) { + at91_twi_write_next_byte(dev); + } + + /* catch error flags */ + dev->transfer_status |= status; + + return IRQ_HANDLED; +} + +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 + * read flag but shows the state of the transmission at the time the + * Status Register is read. According to the programmer datasheet, + * TXCOMP is set when both holding register and internal shifter are + * 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 + * writing the START bit into the Control Register. So the + * corresponding interrupt can safely be enabled just after. + * However for write transactions managed by the CPU, we first write + * into THR, so TXCOMP is cleared. Then we can safely enable TXCOMP + * interrupt. If TXCOMP interrupt were enabled before writing into THR, + * the interrupt handler would be called immediately and the i2c command + * would be reported as completed. + * Also when a write transaction is managed by the DMA controller, + * enabling the TXCOMP interrupt in this function may lead to a race + * 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, 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 %zu bytes.\n", + (dev->msg->flags & I2C_M_RD) ? "read" : "write", dev->buf_len); + + reinit_completion(&dev->cmd_complete); + dev->transfer_status = 0; + + /* Clear pending interrupts, such as NACK. */ + at91_twi_read(dev, AT91_TWI_SR); + + if (dev->fifo_size) { + unsigned fifo_mr = at91_twi_read(dev, AT91_TWI_FMR); + + /* Reset FIFO mode register */ + fifo_mr &= ~(AT91_TWI_FMR_TXRDYM_MASK | + AT91_TWI_FMR_RXRDYM_MASK); + fifo_mr |= AT91_TWI_FMR_TXRDYM(AT91_TWI_ONE_DATA); + fifo_mr |= AT91_TWI_FMR_RXRDYM(AT91_TWI_ONE_DATA); + at91_twi_write(dev, AT91_TWI_FMR, fifo_mr); + + /* Flush FIFOs */ + at91_twi_write(dev, AT91_TWI_CR, + AT91_TWI_THRCLR | AT91_TWI_RHRCLR); + } + + if (!dev->buf_len) { + at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_QUICK); + at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP); + } else if (dev->msg->flags & I2C_M_RD) { + unsigned start_flags = AT91_TWI_START; + + /* if only one byte is to be read, immediately stop transfer */ + if (!dev->use_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 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. + */ + if (dev->use_dma && (dev->buf_len > AT91_I2C_DMA_THRESHOLD)) { + at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_NACK); + at91_twi_read_data_dma(dev); + } else { + at91_twi_write(dev, AT91_TWI_IER, + AT91_TWI_TXCOMP | + AT91_TWI_NACK | + AT91_TWI_RXRDY); + } + } else { + if (dev->use_dma && (dev->buf_len > AT91_I2C_DMA_THRESHOLD)) { + at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_NACK); + at91_twi_write_data_dma(dev); + } else { + at91_twi_write_next_byte(dev); + at91_twi_write(dev, AT91_TWI_IER, + AT91_TWI_TXCOMP | + AT91_TWI_NACK | + AT91_TWI_TXRDY); + } + } + + 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; + goto error; + } + if (dev->transfer_status & AT91_TWI_NACK) { + dev_dbg(dev->dev, "received nack\n"); + ret = -EREMOTEIO; + goto error; + } + if (dev->transfer_status & AT91_TWI_OVRE) { + dev_err(dev->dev, "overrun while reading\n"); + ret = -EIO; + goto error; + } + if (has_unre_flag && dev->transfer_status & AT91_TWI_UNRE) { + dev_err(dev->dev, "underrun while writing\n"); + ret = -EIO; + goto error; + } + if ((has_alt_cmd || dev->fifo_size) && + (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; + goto error; + } + + dev_dbg(dev->dev, "transfer complete\n"); + + 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->fifo_size) && + (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; +} + +static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num) +{ + struct at91_twi_dev *dev = i2c_get_adapdata(adap); + int ret; + unsigned int_addr_flag = 0; + struct i2c_msg *m_start = msg; + bool is_read; + + dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num); + + ret = pm_runtime_get_sync(dev->dev); + if (ret < 0) + goto out; + + if (num == 2) { + int internal_address = 0; + int i; + + /* 1st msg is put into the internal address, start with 2nd */ + m_start = &msg[1]; + for (i = 0; i < msg->len; ++i) { + const unsigned addr = msg->buf[msg->len - 1 - i]; + + internal_address |= addr << (8 * i); + int_addr_flag += AT91_TWI_IADRSZ_1; + } + at91_twi_write(dev, AT91_TWI_IADR, internal_address); + } + + dev->use_alt_cmd = false; + is_read = (m_start->flags & I2C_M_RD); + if (dev->pdata->has_alt_cmd) { + if (m_start->len > 0 && + m_start->len < AT91_I2C_MAX_ALT_CMD_DATA_SIZE) { + 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)); + dev->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 | + ((!dev->use_alt_cmd && is_read) ? AT91_TWI_MREAD : 0)); + + dev->buf_len = m_start->len; + dev->buf = m_start->buf; + dev->msg = m_start; + dev->recv_len_abort = false; + + ret = at91_do_twi_transfer(dev); + + ret = (ret < 0) ? ret : num; +out: + pm_runtime_mark_last_busy(dev->dev); + pm_runtime_put_autosuspend(dev->dev); + + return ret; +} + +/* + * The hardware can handle at most two messages concatenated by a + * repeated start via it's internal address feature. + */ +static const struct i2c_adapter_quirks at91_twi_quirks = { + .flags = I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST | I2C_AQ_COMB_SAME_ADDR, + .max_comb_1st_msg_len = 3, +}; + +static u32 at91_twi_func(struct i2c_adapter *adapter) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL + | I2C_FUNC_SMBUS_READ_BLOCK_DATA; +} + +static const struct i2c_algorithm at91_twi_algorithm = { + .master_xfer = at91_twi_xfer, + .functionality = at91_twi_func, +}; + +static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr) +{ + int ret = 0; + struct dma_slave_config slave_config; + struct at91_twi_dma *dma = &dev->dma; + enum dma_slave_buswidth addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + + /* + * The actual width of the access will be chosen in + * dmaengine_prep_slave_sg(): + * for each buffer in the scatter-gather list, if its size is aligned + * to addr_width then addr_width accesses will be performed to transfer + * the buffer. On the other hand, if the buffer size is not aligned to + * addr_width then the buffer is transferred using single byte accesses. + * Please refer to the Atmel eXtended DMA controller driver. + * When FIFOs are used, the TXRDYM threshold can always be set to + * trigger the XDMAC when at least 4 data can be written into the TX + * FIFO, even if single byte accesses are performed. + * However the RXRDYM threshold must be set to fit the access width, + * deduced from buffer length, so the XDMAC is triggered properly to + * read data from the RX FIFO. + */ + if (dev->fifo_size) + addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES; + + memset(&slave_config, 0, sizeof(slave_config)); + slave_config.src_addr = (dma_addr_t)phy_addr + AT91_TWI_RHR; + slave_config.src_addr_width = addr_width; + slave_config.src_maxburst = 1; + slave_config.dst_addr = (dma_addr_t)phy_addr + AT91_TWI_THR; + slave_config.dst_addr_width = addr_width; + slave_config.dst_maxburst = 1; + slave_config.device_fc = false; + + dma->chan_tx = dma_request_slave_channel_reason(dev->dev, "tx"); + if (IS_ERR(dma->chan_tx)) { + ret = PTR_ERR(dma->chan_tx); + dma->chan_tx = NULL; + goto error; + } + + dma->chan_rx = dma_request_slave_channel_reason(dev->dev, "rx"); + if (IS_ERR(dma->chan_rx)) { + ret = PTR_ERR(dma->chan_rx); + dma->chan_rx = NULL; + goto error; + } + + slave_config.direction = DMA_MEM_TO_DEV; + if (dmaengine_slave_config(dma->chan_tx, &slave_config)) { + dev_err(dev->dev, "failed to configure tx channel\n"); + ret = -EINVAL; + goto error; + } + + slave_config.direction = DMA_DEV_TO_MEM; + if (dmaengine_slave_config(dma->chan_rx, &slave_config)) { + dev_err(dev->dev, "failed to configure rx channel\n"); + ret = -EINVAL; + goto error; + } + + sg_init_table(dma->sg, 2); + dma->buf_mapped = false; + dma->xfer_in_progress = false; + dev->use_dma = true; + + dev_info(dev->dev, "using %s (tx) and %s (rx) for DMA transfers\n", + dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx)); + + return ret; + +error: + if (ret != -EPROBE_DEFER) + dev_info(dev->dev, "can't get DMA channel, continue without DMA support\n"); + if (dma->chan_rx) + dma_release_channel(dma->chan_rx); + if (dma->chan_tx) + dma_release_channel(dma->chan_tx); + return ret; +} + +int at91_twi_probe_master(struct platform_device *pdev, + u32 phy_addr, struct at91_twi_dev *dev) +{ + int rc; + + init_completion(&dev->cmd_complete); + + rc = devm_request_irq(&pdev->dev, dev->irq, atmel_twi_interrupt, 0, + dev_name(dev->dev), dev); + if (rc) { + dev_err(dev->dev, "Cannot get irq %d: %d\n", dev->irq, rc); + return rc; + } + + if (dev->dev->of_node) { + rc = at91_twi_configure_dma(dev, phy_addr); + if (rc == -EPROBE_DEFER) + return rc; + } + + if (!of_property_read_u32(pdev->dev.of_node, "atmel,fifo-size", + &dev->fifo_size)) { + dev_info(dev->dev, "Using FIFO (%u data)\n", dev->fifo_size); + } + + at91_calc_twi_clock(dev); + + dev->adapter.algo = &at91_twi_algorithm; + dev->adapter.quirks = &at91_twi_quirks; + + return 0; +} |