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Diffstat (limited to 'drivers/i2c/busses/i2c-at91.c')
-rw-r--r--drivers/i2c/busses/i2c-at91.c147
1 files changed, 130 insertions, 17 deletions
diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index abd93f3a05a0..9e54f97a9020 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -54,6 +54,8 @@
#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_FIFOEN BIT(28) /* FIFO Enable */
+#define AT91_TWI_FIFODIS BIT(29) /* FIFO Disable */
#define AT91_TWI_MMR 0x0004 /* Master Mode Register */
#define AT91_TWI_IADRSZ_1 0x0100 /* Internal Device Address Size */
@@ -85,6 +87,22 @@
#define AT91_TWI_ACR_DATAL(len) ((len) & 0xff)
#define AT91_TWI_ACR_DIR BIT(8)
+#define AT91_TWI_FMR 0x0050 /* FIFO Mode Register */
+#define AT91_TWI_FMR_TXRDYM(mode) (((mode) & 0x3) << 0)
+#define AT91_TWI_FMR_TXRDYM_MASK (0x3 << 0)
+#define AT91_TWI_FMR_RXRDYM(mode) (((mode) & 0x3) << 4)
+#define AT91_TWI_FMR_RXRDYM_MASK (0x3 << 4)
+#define AT91_TWI_ONE_DATA 0x0
+#define AT91_TWI_TWO_DATA 0x1
+#define AT91_TWI_FOUR_DATA 0x2
+
+#define AT91_TWI_FLR 0x0054 /* FIFO Level Register */
+
+#define AT91_TWI_FSR 0x0060 /* FIFO Status Register */
+#define AT91_TWI_FIER 0x0064 /* FIFO Interrupt Enable Register */
+#define AT91_TWI_FIDR 0x0068 /* FIFO Interrupt Disable Register */
+#define AT91_TWI_FIMR 0x006c /* FIFO Interrupt Mask Register */
+
#define AT91_TWI_VER 0x00fc /* Version Register */
struct at91_twi_pdata {
@@ -98,7 +116,7 @@ struct at91_twi_pdata {
struct at91_twi_dma {
struct dma_chan *chan_rx;
struct dma_chan *chan_tx;
- struct scatterlist sg;
+ struct scatterlist sg[2];
struct dma_async_tx_descriptor *data_desc;
enum dma_data_direction direction;
bool buf_mapped;
@@ -121,6 +139,7 @@ struct at91_twi_dev {
struct at91_twi_pdata *pdata;
bool use_dma;
bool recv_len_abort;
+ u32 fifo_size;
struct at91_twi_dma dma;
};
@@ -154,6 +173,9 @@ static void at91_init_twi_bus(struct at91_twi_dev *dev)
{
at91_disable_twi_interrupts(dev);
at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SWRST);
+ /* 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);
@@ -200,7 +222,7 @@ static void at91_twi_dma_cleanup(struct at91_twi_dev *dev)
dma->xfer_in_progress = false;
}
if (dma->buf_mapped) {
- dma_unmap_single(dev->dev, sg_dma_address(&dma->sg),
+ dma_unmap_single(dev->dev, sg_dma_address(&dma->sg[0]),
dev->buf_len, dma->direction);
dma->buf_mapped = false;
}
@@ -213,7 +235,8 @@ static void at91_twi_write_next_byte(struct at91_twi_dev *dev)
if (dev->buf_len <= 0)
return;
- at91_twi_write(dev, AT91_TWI_THR, *dev->buf);
+ /* 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)
@@ -229,7 +252,7 @@ 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),
+ dma_unmap_single(dev->dev, sg_dma_address(&dev->dma.sg[0]),
dev->buf_len, DMA_TO_DEVICE);
/*
@@ -250,6 +273,7 @@ static void at91_twi_write_data_dma(struct at91_twi_dev *dev)
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 <= 0)
return;
@@ -265,10 +289,43 @@ static void at91_twi_write_data_dma(struct at91_twi_dev *dev)
}
dma->buf_mapped = true;
at91_twi_irq_restore(dev);
- sg_dma_len(&dma->sg) = dev->buf_len;
- sg_dma_address(&dma->sg) = dma_addr;
- txdesc = dmaengine_prep_slave_sg(chan_tx, &dma->sg, 1, DMA_MEM_TO_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");
@@ -293,7 +350,8 @@ static void at91_twi_read_next_byte(struct at91_twi_dev *dev)
if (dev->buf_len <= 0)
return;
- *dev->buf = at91_twi_read(dev, AT91_TWI_RHR) & 0xff;
+ /* 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*/
@@ -330,7 +388,7 @@ 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),
+ dma_unmap_single(dev->dev, sg_dma_address(&dev->dma.sg[0]),
dev->buf_len, DMA_FROM_DEVICE);
if (!dev->pdata->has_alt_cmd) {
@@ -362,10 +420,24 @@ 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) = buf_len;
- rxdesc = dmaengine_prep_slave_sg(chan_rx, &dma->sg, 1, DMA_DEV_TO_MEM,
+ 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");
@@ -465,6 +537,21 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
reinit_completion(&dev->cmd_complete);
dev->transfer_status = 0;
+ 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);
@@ -536,7 +623,8 @@ 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)) {
+ if ((has_alt_cmd || dev->fifo_size) &&
+ (dev->transfer_status & AT91_TWI_LOCK)) {
dev_err(dev->dev, "tx locked\n");
ret = -EIO;
goto error;
@@ -555,7 +643,8 @@ 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)) {
+ 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);
@@ -750,13 +839,32 @@ 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 = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ 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 = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ slave_config.dst_addr_width = addr_width;
slave_config.dst_maxburst = 1;
slave_config.device_fc = false;
@@ -788,7 +896,7 @@ static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
goto error;
}
- sg_init_table(&dma->sg, 1);
+ sg_init_table(dma->sg, 2);
dma->buf_mapped = false;
dma->xfer_in_progress = false;
dev->use_dma = true;
@@ -874,6 +982,11 @@ static int at91_twi_probe(struct platform_device *pdev)
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);
+ }
+
rc = of_property_read_u32(dev->dev->of_node, "clock-frequency",
&bus_clk_rate);
if (rc)
generated by cgit v1.2.3 (git 2.25.1) at 2024-09-05 23:29:09 +0000