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linux-sg2042/drivers/i2c/busses/i2c-at91-master.c

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// 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;
}
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