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Date: Wed, 19 Jun 2024 10:05:58 +0000
From: Aisheng Dong <aisheng.dong@....com>
To: Carlos Song <carlos.song@....com>, "andi.shyti@...nel.org"
<andi.shyti@...nel.org>, "shawnguo@...nel.org" <shawnguo@...nel.org>,
"s.hauer@...gutronix.de" <s.hauer@...gutronix.de>, "kernel@...gutronix.de"
<kernel@...gutronix.de>, "festevam@...il.com" <festevam@...il.com>,
"sumit.semwal@...aro.org" <sumit.semwal@...aro.org>,
"christian.koenig@....com" <christian.koenig@....com>
CC: Frank Li <frank.li@....com>, "linux-i2c@...r.kernel.org"
<linux-i2c@...r.kernel.org>, "imx@...ts.linux.dev" <imx@...ts.linux.dev>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>, "linux-media@...r.kernel.org"
<linux-media@...r.kernel.org>, "dri-devel@...ts.freedesktop.org"
<dri-devel@...ts.freedesktop.org>, "linaro-mm-sig@...ts.linaro.org"
<linaro-mm-sig@...ts.linaro.org>
Subject: RE: [Patch V3] i2c: imx-lpi2c: add eDMA mode support for LPI2C
> From: Carlos Song <carlos.song@....com>
> Sent: 2024年6月14日 12:56
>
> Add eDMA mode support for LPI2C.
>
> There are some differences between TX DMA mode and RX DMA mode.
> LPI2C MTDR register is Controller Transmit Data Register.
> When lpi2c send data, it is tx cmd register and tx data fifo.
> When lpi2c receive data, it is just a rx cmd register. LPI2C MRDR register is
> Controller Receive Data Register, received data are stored in this.
>
> MTDR[8:10] is CMD field and MTDR[0:7] is DATA filed.
> +-----------+-------------------------------+
> | C M D | D A T A |
> +---+---+---+---+---+---+---+---+---+---+---+
> | 10| 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
> +---+---+---+---+---+---+---+---+---+---+---+
>
> MRDR is Controller Receive Data Register.
> MRDR[0:7] is DATA filed.
> +-------------------------------+
> | D A T A |
> +---+---+---+---+---+---+---+---+
> | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
> +---+---+---+---+---+---+---+---+
>
> When the LPI2C controller needs to send data, tx cmd and 8-bit data should be
> written into MTDR:
> CMD: 000b: Transmit the value in DATA[7:0].
> DATA: 8-bit data.
>
> If lpi2c controller needs to send N 8-bit data, just write N times
> (CMD(W) + DATA(u8)) to MTDR.
>
> When the LPI2C controller needs to receive data, rx cmd should be written into
> MTDR, the received data will be stored in the MRDR.
>
> MTDR(CMD): 001b: Receive (DATA[7:0] + 1) 8-bit data.
> MTDR(DATA): byte counter.
> MRDR(DATA): 8-bit data.
>
> So when lpi2c controller needs to receive N 8-bit data, 1. N <= 256:
> Write 1 time (CMD(R) + BYTE COUNT(N-1)) into MTDR and receive data from
> MRDR.
> 2. N > 256:
> Write N/256 times (CMD(R) + BYTE COUNT(255)) + 1 time (CMD(R) + BYTE
> COUNT(N%256)) into MTDR and receive data from MRDR.
>
> Due to these differences, when lpi2c is in DMA TX mode, only enable TX
> channel to send data. But when lpi2c is in DMA RX mode, TX and RX channel
> are both enabled, TX channel is used to send RX cmd and RX channel is used to
> receive data.
>
> Signed-off-by: Carlos Song <carlos.song@....com>
> Reviewed-by: Frank Li <frank.li@....com>
> ---
> Change for V3:
> Optimize DMA timeout calculate function names and variables avoid confusing
> Change for V2:
> Optimized eDMA rx cmd buf free function to improve code readability
> ---
> drivers/i2c/busses/i2c-imx-lpi2c.c | 531 ++++++++++++++++++++++++++++-
> 1 file changed, 523 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c
> b/drivers/i2c/busses/i2c-imx-lpi2c.c
> index 0197786892a2..d1ef0e3aa3f5 100644
> --- a/drivers/i2c/busses/i2c-imx-lpi2c.c
> +++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
> @@ -8,6 +8,8 @@
> #include <linux/clk.h>
> #include <linux/completion.h>
> #include <linux/delay.h>
> +#include <linux/dmaengine.h>
> +#include <linux/dma-mapping.h>
> #include <linux/err.h>
> #include <linux/errno.h>
> #include <linux/i2c.h>
> @@ -29,6 +31,7 @@
> #define LPI2C_MCR 0x10 /* i2c contrl register */
> #define LPI2C_MSR 0x14 /* i2c status register */
> #define LPI2C_MIER 0x18 /* i2c interrupt enable */
> +#define LPI2C_MDER 0x1C /* i2c DMA enable */
> #define LPI2C_MCFGR0 0x20 /* i2c master configuration */
> #define LPI2C_MCFGR1 0x24 /* i2c master configuration */
> #define LPI2C_MCFGR2 0x28 /* i2c master configuration */
> @@ -70,11 +73,14 @@
> #define MCFGR1_AUTOSTOP BIT(8)
> #define MCFGR1_IGNACK BIT(9)
> #define MRDR_RXEMPTY BIT(14)
> +#define MDER_TDDE BIT(0)
> +#define MDER_RDDE BIT(1)
>
> #define I2C_CLK_RATIO 2
> #define CHUNK_DATA 256
>
> #define I2C_PM_TIMEOUT 10 /* ms */
> +#define I2C_DMA_THRESHOLD 8 /* bytes */
>
> enum lpi2c_imx_mode {
> STANDARD, /* 100+Kbps */
> @@ -108,6 +114,22 @@ struct lpi2c_imx_struct {
> unsigned int rxfifosize;
> enum lpi2c_imx_mode mode;
> struct i2c_bus_recovery_info rinfo;
> +
> + bool can_use_dma;
> + bool using_pio_mode;
> + u8 rx_cmd_buf_len;
> + u16 *rx_cmd_buf;
> + u8 *dma_buf;
> + unsigned int dma_len;
> + unsigned int tx_burst_num;
> + unsigned int rx_burst_num;
> + resource_size_t phy_addr;
> + dma_addr_t dma_tx_addr;
> + dma_addr_t dma_addr;
> + enum dma_data_direction dma_direction;
> + struct dma_chan *chan_tx;
> + struct dma_chan *chan_rx;
> + struct i2c_msg *msg;
> };
>
> static void lpi2c_imx_intctrl(struct lpi2c_imx_struct *lpi2c_imx, @@ -305,7
> +327,7 @@ static int lpi2c_imx_master_disable(struct lpi2c_imx_struct
> *lpi2c_imx)
> return 0;
> }
>
> -static int lpi2c_imx_msg_complete(struct lpi2c_imx_struct *lpi2c_imx)
> +static int lpi2c_imx_pio_msg_complete(struct lpi2c_imx_struct
> +*lpi2c_imx)
> {
> unsigned long time_left;
>
> @@ -451,6 +473,439 @@ static void lpi2c_imx_read(struct lpi2c_imx_struct
> *lpi2c_imx,
> lpi2c_imx_intctrl(lpi2c_imx, MIER_RDIE | MIER_NDIE); }
>
> +static bool is_use_dma(struct lpi2c_imx_struct *lpi2c_imx, struct
> +i2c_msg *msg) {
> + if (!lpi2c_imx->can_use_dma)
> + return false;
> +
> + /*
> + * When the length of data is less than I2C_DMA_THRESHOLD,
> + * cpu mode is used directly to avoid low performance.
> + */
> + if (msg->len < I2C_DMA_THRESHOLD)
> + return false;
> +
> + return true;
> +}
> +
> +static int lpi2c_imx_pio_xfer(struct lpi2c_imx_struct *lpi2c_imx,
> + struct i2c_msg *msg)
> +{
> + int result;
if no special meaning,
s/result/ret
> +
> + reinit_completion(&lpi2c_imx->complete);
> +
> + if (msg->flags & I2C_M_RD)
> + lpi2c_imx_read(lpi2c_imx, msg);
> + else
> + lpi2c_imx_write(lpi2c_imx, msg);
> +
> + result = lpi2c_imx_pio_msg_complete(lpi2c_imx);
> + if (result)
> + return result;
> +
> + return 0;
> +}
> +
> +static int lpi2c_imx_dma_timeout_calculate(struct lpi2c_imx_struct
> +*lpi2c_imx) {
> + unsigned long time = 0;
> +
> + time = 8 * lpi2c_imx->msglen * 1000 / lpi2c_imx->bitrate;
> +
> + /* Add extra second for scheduler related activities */
> + time += 1;
> +
> + /* Double calculated time */
> + return msecs_to_jiffies(time * MSEC_PER_SEC); }
> +
> +static int lpi2c_imx_alloc_rx_cmd_buf(struct lpi2c_imx_struct
> +*lpi2c_imx) {
> + u16 rx_remain = lpi2c_imx->msg->len;
> + u16 temp;
> + int cmd_num;
> +
> + /*
> + * Calculate the number of rx command words via the DMA TX channel
> + * writing into command register based on the i2c msg len, and build
> + * the rx command words buffer.
> + */
> + cmd_num = DIV_ROUND_UP(rx_remain, CHUNK_DATA);
> + lpi2c_imx->rx_cmd_buf = kcalloc(cmd_num, sizeof(u16), GFP_KERNEL);
> + lpi2c_imx->rx_cmd_buf_len = cmd_num * sizeof(u16);
> +
> + if (!lpi2c_imx->rx_cmd_buf) {
> + dev_err(&lpi2c_imx->adapter.dev, "Alloc RX cmd buffer failed\n");
> + return -ENOMEM;
> + }
> +
> + for (int i = 0; i < cmd_num ; i++) {
> + temp = rx_remain > CHUNK_DATA ? CHUNK_DATA - 1 : rx_remain - 1;
> + temp |= (RECV_DATA << 8);
> + rx_remain -= CHUNK_DATA;
> + lpi2c_imx->rx_cmd_buf[i] = temp;
> + }
> +
> + return 0;
> +}
> +
> +static int lpi2c_imx_dma_msg_complete(struct lpi2c_imx_struct
> +*lpi2c_imx) {
> + unsigned long time_left, time;
> +
> + time = lpi2c_imx_dma_timeout_calculate(lpi2c_imx);
> + time_left = wait_for_completion_timeout(&lpi2c_imx->complete, time);
> + if (time_left == 0) {
> + dev_err(&lpi2c_imx->adapter.dev, "I/O Error in DMA Data
> Transfer\n");
> + return -ETIMEDOUT;
> + }
> +
> + return 0;
> +}
> +
> +static void lpi2c_dma_unmap(struct lpi2c_imx_struct *lpi2c_imx) {
> + struct dma_chan *chan = lpi2c_imx->dma_direction ==
> DMA_FROM_DEVICE
> + ? lpi2c_imx->chan_rx : lpi2c_imx->chan_tx;
> +
> + dma_unmap_single(chan->device->dev, lpi2c_imx->dma_addr,
> + lpi2c_imx->dma_len, lpi2c_imx->dma_direction);
> +
> + lpi2c_imx->dma_direction = DMA_NONE;
> +}
> +
> +static void lpi2c_cleanup_rx_cmd_dma(struct lpi2c_imx_struct
> +*lpi2c_imx) {
> + dmaengine_terminate_sync(lpi2c_imx->chan_tx);
> + dma_unmap_single(lpi2c_imx->chan_tx->device->dev,
> lpi2c_imx->dma_tx_addr,
> + lpi2c_imx->rx_cmd_buf_len, DMA_TO_DEVICE); }
> +
> +static void lpi2c_cleanup_dma(struct lpi2c_imx_struct *lpi2c_imx) {
> + if (lpi2c_imx->dma_direction == DMA_NONE)
> + return;
> + else if (lpi2c_imx->dma_direction == DMA_FROM_DEVICE)
> + dmaengine_terminate_sync(lpi2c_imx->chan_rx);
> + else if (lpi2c_imx->dma_direction == DMA_TO_DEVICE)
> + dmaengine_terminate_sync(lpi2c_imx->chan_tx);
> +
> + lpi2c_dma_unmap(lpi2c_imx);
> +}
> +
> +static void lpi2c_dma_callback(void *data) {
> + struct lpi2c_imx_struct *lpi2c_imx = (struct lpi2c_imx_struct *)data;
> +
> + complete(&lpi2c_imx->complete);
> +}
> +
> +static int lpi2c_dma_rx_cmd_submit(struct lpi2c_imx_struct *lpi2c_imx)
> +{
> + struct dma_chan *txchan = lpi2c_imx->chan_tx;
> + struct dma_async_tx_descriptor *rx_cmd_desc;
> + dma_cookie_t cookie;
> +
> + lpi2c_imx->dma_tx_addr = dma_map_single(txchan->device->dev,
> + lpi2c_imx->rx_cmd_buf,
> + lpi2c_imx->rx_cmd_buf_len, DMA_TO_DEVICE);
> + if (dma_mapping_error(txchan->device->dev, lpi2c_imx->dma_tx_addr)) {
> + dev_err(&lpi2c_imx->adapter.dev, "dma map failed, use pio\n");
> + return -EINVAL;
> + }
> +
> + rx_cmd_desc = dmaengine_prep_slave_single(txchan,
> lpi2c_imx->dma_tx_addr,
> + lpi2c_imx->rx_cmd_buf_len, DMA_MEM_TO_DEV,
> + DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> + if (!rx_cmd_desc) {
> + dma_unmap_single(txchan->device->dev, lpi2c_imx->dma_tx_addr,
> + lpi2c_imx->rx_cmd_buf_len, DMA_TO_DEVICE);
> + dev_err(&lpi2c_imx->adapter.dev, "dma prep slave sg failed, use
> pio\n");
> + return -EINVAL;
> + }
> +
> +
Drop one blank line
> + cookie = dmaengine_submit(rx_cmd_desc);
> + if (dma_submit_error(cookie)) {
> + dma_unmap_single(txchan->device->dev, lpi2c_imx->dma_tx_addr,
> + lpi2c_imx->rx_cmd_buf_len, DMA_TO_DEVICE);
> + dmaengine_desc_free(rx_cmd_desc);
> + dev_err(&lpi2c_imx->adapter.dev, "submitting dma failed, use
> pio\n");
> + return -EINVAL;
> + }
> +
> + dma_async_issue_pending(txchan);
> +
> + return 0;
> +}
> +
> +static int lpi2c_dma_submit(struct lpi2c_imx_struct *lpi2c_imx) {
> + bool read = lpi2c_imx->msg->flags & I2C_M_RD;
> + enum dma_data_direction dir = read ? DMA_FROM_DEVICE :
> DMA_TO_DEVICE;
> + struct dma_chan *chan = read ? lpi2c_imx->chan_rx : lpi2c_imx->chan_tx;
> + struct dma_async_tx_descriptor *desc;
> + dma_cookie_t cookie;
> +
> + lpi2c_imx->dma_direction = dir;
> +
> + lpi2c_imx->dma_addr = dma_map_single(chan->device->dev,
> + lpi2c_imx->dma_buf,
> + lpi2c_imx->dma_len, dir);
> + if (dma_mapping_error(chan->device->dev, lpi2c_imx->dma_addr)) {
> + dev_err(&lpi2c_imx->adapter.dev, "dma map failed, use pio\n");
> + return -EINVAL;
> + }
> +
> + desc = dmaengine_prep_slave_single(chan, lpi2c_imx->dma_addr,
> + lpi2c_imx->dma_len, read ?
> + DMA_DEV_TO_MEM : DMA_MEM_TO_DEV,
> + DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> + if (!desc) {
> + dev_err(&lpi2c_imx->adapter.dev, "dma prep slave sg failed, use
> pio\n");
> + lpi2c_dma_unmap(lpi2c_imx);
> + return -EINVAL;
> + }
> +
> + reinit_completion(&lpi2c_imx->complete);
> + desc->callback = lpi2c_dma_callback;
> + desc->callback_param = (void *)lpi2c_imx;
> +
> + cookie = dmaengine_submit(desc);
> + if (dma_submit_error(cookie)) {
> + dev_err(&lpi2c_imx->adapter.dev, "submitting dma failed, use
> pio\n");
> + lpi2c_dma_unmap(lpi2c_imx);
> + dmaengine_desc_free(desc);
> + return -EINVAL;
> + }
> +
> + /* Can't switch to PIO mode when DMA have started transferred */
s/transferred/transfer
> + lpi2c_imx->using_pio_mode = false;
> +
> + dma_async_issue_pending(chan);
> +
> + return 0;
> +}
> +
> +static int lpi2c_imx_find_max_burst_num(unsigned int fifosize, unsigned
> +int len) {
> + unsigned int i;
> +
> + for (i = fifosize / 2; i > 0; i--) {
> + if (!(len % i))
> + break;
> + }
> +
> + return i;
> +}
One more blank line
> +/*
> + * For a highest DMA efficiency, tx/rx burst number should be
> +calculated according to
> + * the FIFO depth.
> + */
> +static void lpi2c_imx_dma_burst_num_calculate(struct lpi2c_imx_struct
> +*lpi2c_imx) {
> + unsigned int cmd_num;
> +
> + if (lpi2c_imx->msg->flags & I2C_M_RD) {
> + /*
> + * One RX cmd word can trigger DMA receive no more than 256
> bytes.
> + * The number of RX cmd words should be calculated based on the
> data
> + * length.
> + */
> + cmd_num = DIV_ROUND_UP(lpi2c_imx->dma_len, CHUNK_DATA);
> + lpi2c_imx->tx_burst_num =
> lpi2c_imx_find_max_burst_num(lpi2c_imx->txfifosize,
> + cmd_num);
> + lpi2c_imx->rx_burst_num =
> lpi2c_imx_find_max_burst_num(lpi2c_imx->rxfifosize,
> + lpi2c_imx->dma_len);
> + } else
> + lpi2c_imx->tx_burst_num =
> lpi2c_imx_find_max_burst_num(lpi2c_imx->txfifosize,
> + lpi2c_imx->dma_len);
> +}
> +
> +static int lpi2c_dma_config(struct lpi2c_imx_struct *lpi2c_imx) {
> + int ret;
> + struct dma_slave_config rx = {}, tx = {};
> +
> + lpi2c_imx_dma_burst_num_calculate(lpi2c_imx);
> +
> + if (lpi2c_imx->msg->flags & I2C_M_RD) {
> + if (IS_ERR(lpi2c_imx->chan_tx)) {
> + ret = PTR_ERR(lpi2c_imx->chan_tx);
> + dev_err(&lpi2c_imx->adapter.dev, "can't get RX channel %d\n",
> ret);
> + return ret;
> + }
> +
> + if (IS_ERR(lpi2c_imx->chan_rx)) {
> + ret = PTR_ERR(lpi2c_imx->chan_rx);
> + dev_err(&lpi2c_imx->adapter.dev, "can't get TX channel %d\n",
> ret);
> + return ret;
> + }
Duplicated checking with lpi2c_dma_init()?
> +
> + tx.dst_addr = lpi2c_imx->phy_addr + LPI2C_MTDR;
> + tx.dst_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
> + tx.dst_maxburst = lpi2c_imx->tx_burst_num;
> + tx.direction = DMA_MEM_TO_DEV;
> + ret = dmaengine_slave_config(lpi2c_imx->chan_tx, &tx);
> + if (ret < 0) {
> + dev_err(&lpi2c_imx->adapter.dev, "can't configure TX
> channel %d\n", ret);
> + return ret;
> + }
> +
> + rx.src_addr = lpi2c_imx->phy_addr + LPI2C_MRDR;
> + rx.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
> + rx.src_maxburst = lpi2c_imx->rx_burst_num;
> + rx.direction = DMA_DEV_TO_MEM;
> + ret = dmaengine_slave_config(lpi2c_imx->chan_rx, &rx);
> + if (ret < 0) {
> + dev_err(&lpi2c_imx->adapter.dev, "can't configure RX
> channel %d\n", ret);
> + return ret;
> + }
> + } else {
> + if (IS_ERR(lpi2c_imx->chan_tx)) {
> + ret = PTR_ERR(lpi2c_imx->chan_tx);
> + dev_err(&lpi2c_imx->adapter.dev, "can't get TX channel %d\n",
> ret);
> + return ret;
> + }
Ditto
> +
> + tx.dst_addr = lpi2c_imx->phy_addr + LPI2C_MTDR;
> + tx.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
> + tx.dst_maxburst = lpi2c_imx->tx_burst_num;
> + tx.direction = DMA_MEM_TO_DEV;
> + ret = dmaengine_slave_config(lpi2c_imx->chan_tx, &tx);
> + if (ret < 0) {
> + dev_err(&lpi2c_imx->adapter.dev, "can't configure TX
> channel %d\n", ret);
> + return ret;
> + }
> + }
> +
> + return 0;
> +}
> +
> +static void lpi2c_dma_enable(struct lpi2c_imx_struct *lpi2c_imx) {
> + /*
> + * TX interrupt will be triggerred when the number of words in the
> transmit FIFO is equal
> + * or less than TX watermark. RX interrupt will be triggerred when the
> number of words
> + * in the receive FIFO is greater than RX watermark. In order to trigger the
> DMA interrupt,
> + * TX watermark should be set equal to the DMA TX burst number but RX
> watermark should be
> + * set less than the DMA RX burst number.
> + */
> + if (lpi2c_imx->msg->flags & I2C_M_RD) {
> + /* Set I2C TX/RX watermark */
> + writel(lpi2c_imx->tx_burst_num | (lpi2c_imx->rx_burst_num - 1) <<
> 16,
> + lpi2c_imx->base + LPI2C_MFCR);
> + /* Enable I2C DMA TX/RX function */
> + writel(MDER_TDDE | MDER_RDDE, lpi2c_imx->base + LPI2C_MDER);
> + } else {
> + /* Set I2C TX watermark */
> + writel(lpi2c_imx->tx_burst_num, lpi2c_imx->base + LPI2C_MFCR);
> + /* Enable I2C DMA TX function */
> + writel(MDER_TDDE, lpi2c_imx->base + LPI2C_MDER);
> + }
> +
> + /* Enable NACK detected */
> + lpi2c_imx_intctrl(lpi2c_imx, MIER_NDIE); };
> +
> +/*
> + * When lpi2c in TX DMA mode we can use one DMA TX channel to write
> +data word
> + * into TXFIFO, but in RX DMA mode it is different.
> + *
> + * LPI2C MTDR register is a command data and transmit data register.
> + * Bit 8-10 is a command data field and Bit 0-7 is a transmit data
> + * field. When the LPI2C master needs to read data, the data number
> + * to read should be set in transmit data field and RECV_DATA should
> + * be set into the command data field to receive (DATA[7:0] + 1) bytes.
> + * The recv data command word is made by RECV_DATA in command data
> +field
> + * and the data number to read in transmit data field. when the length
> + * of the data that needs to be read exceeds 256 bytes, recv data
> +command
> + * word needs to be written to TXFIFO multiple times.
> + *
> + * So when in RX DMA mode, the TX channel also needs to be configured
> +additionally
> + * to send RX command words and the RX command word need be set in
> +advance before
> + * transmitting.
> + */
> +static int lpi2c_imx_dma_xfer(struct lpi2c_imx_struct *lpi2c_imx,
> + struct i2c_msg *msg)
> +{
> + int result;
Any special meaning of 'result'? If no, pls simply use 'ret' instead
> +
> + lpi2c_imx->msg = msg;
> + lpi2c_imx->dma_len = msg->len;
> + lpi2c_imx->dma_buf = i2c_get_dma_safe_msg_buf(msg,
> + I2C_DMA_THRESHOLD);
> +
> + if (!lpi2c_imx->dma_buf)
> + return -ENOMEM;
> +
> + result = lpi2c_dma_config(lpi2c_imx);
> + if (result) {
> + dev_err(&lpi2c_imx->adapter.dev, "DMA Config Fail, error %d\n",
> result);
> + goto disable_dma;
> + }
> +
> + lpi2c_dma_enable(lpi2c_imx);
> +
> + result = lpi2c_dma_submit(lpi2c_imx);
> + if (result) {
> + dev_err(&lpi2c_imx->adapter.dev, "DMA submit Fail, error %d\n",
> result);
> + goto disable_dma;
> + }
> +
> + if (msg->flags & I2C_M_RD) {
> + result = lpi2c_imx_alloc_rx_cmd_buf(lpi2c_imx);
> + if (result) {
> + lpi2c_cleanup_dma(lpi2c_imx);
> + goto disable_dma;
> + }
> +
> + result = lpi2c_dma_rx_cmd_submit(lpi2c_imx);
> + if (result) {
> + lpi2c_cleanup_dma(lpi2c_imx);
> + goto disable_dma;
> + }
> + }
> +
> + result = lpi2c_imx_dma_msg_complete(lpi2c_imx);
> + if (result) {
> + if (msg->flags & I2C_M_RD)
> + lpi2c_cleanup_rx_cmd_dma(lpi2c_imx);
> + lpi2c_cleanup_dma(lpi2c_imx);
> + goto disable_dma;
> + }
> +
> + /* When meet NACK in transfer, cleanup all DMA transfer */
> + if ((readl(lpi2c_imx->base + LPI2C_MSR) & MSR_NDF) && !result) {
> + if (msg->flags & I2C_M_RD)
> + lpi2c_cleanup_rx_cmd_dma(lpi2c_imx);
> + lpi2c_cleanup_dma(lpi2c_imx);
> + result = -EIO;
> + goto disable_dma;
> + }
> +
> + if (msg->flags & I2C_M_RD)
> + dma_unmap_single(lpi2c_imx->chan_tx->device->dev,
> lpi2c_imx->dma_tx_addr,
> + lpi2c_imx->rx_cmd_buf_len, DMA_TO_DEVICE);
> + lpi2c_dma_unmap(lpi2c_imx);
> +
> +disable_dma:
> + /* Disable I2C DMA function */
> + writel(0, lpi2c_imx->base + LPI2C_MDER);
> +
> + if (lpi2c_imx->msg->flags & I2C_M_RD)
> + kfree(lpi2c_imx->rx_cmd_buf);
> +
> + if (result)
> + i2c_put_dma_safe_msg_buf(lpi2c_imx->dma_buf,
> + lpi2c_imx->msg, false);
> + else
> + i2c_put_dma_safe_msg_buf(lpi2c_imx->dma_buf,
> + lpi2c_imx->msg, true);
> + return result;
> +}
> +
> static int lpi2c_imx_xfer(struct i2c_adapter *adapter,
> struct i2c_msg *msgs, int num)
> {
> @@ -475,14 +930,17 @@ static int lpi2c_imx_xfer(struct i2c_adapter
> *adapter,
> lpi2c_imx->tx_buf = NULL;
> lpi2c_imx->delivered = 0;
> lpi2c_imx->msglen = msgs[i].len;
> - init_completion(&lpi2c_imx->complete);
>
> - if (msgs[i].flags & I2C_M_RD)
> - lpi2c_imx_read(lpi2c_imx, &msgs[i]);
> - else
> - lpi2c_imx_write(lpi2c_imx, &msgs[i]);
> + /* When DMA mode failed before transferring, CPU mode can be
> used. */
> + lpi2c_imx->using_pio_mode = true;
Probably better moving this line into lpi2c_imx_dma_xfer() for better code reading
> +
> + if (is_use_dma(lpi2c_imx, &msgs[i])) {
> + result = lpi2c_imx_dma_xfer(lpi2c_imx, &msgs[i]);
> + if (result && lpi2c_imx->using_pio_mode)
> + result = lpi2c_imx_pio_xfer(lpi2c_imx, &msgs[i]);
> + } else
> + result = lpi2c_imx_pio_xfer(lpi2c_imx, &msgs[i]);
>
> - result = lpi2c_imx_msg_complete(lpi2c_imx);
> if (result)
> goto stop;
>
> @@ -546,6 +1004,49 @@ static int lpi2c_imx_init_recovery_info(struct
> lpi2c_imx_struct *lpi2c_imx,
> return 0;
> }
>
> +static void lpi2c_dma_exit(struct lpi2c_imx_struct *lpi2c_imx) {
> + if (lpi2c_imx->chan_rx) {
> + dma_release_channel(lpi2c_imx->chan_rx);
> + lpi2c_imx->chan_rx = NULL;
> + }
> +
> + if (lpi2c_imx->chan_tx) {
> + dma_release_channel(lpi2c_imx->chan_tx);
> + lpi2c_imx->chan_tx = NULL;
> + }
> +}
> +
> +static int lpi2c_dma_init(struct device *dev,
> + struct lpi2c_imx_struct *lpi2c_imx) {
> + int ret;
> +
> + lpi2c_imx->chan_rx = lpi2c_imx->chan_tx = NULL;
Unnecessary assignment
> + lpi2c_imx->can_use_dma = false;
Ditto
> +
> + /* Prepare for TX DMA: */
> + lpi2c_imx->chan_tx = dma_request_chan(dev, "tx");
> + if (IS_ERR(lpi2c_imx->chan_tx)) {
> + ret = PTR_ERR(lpi2c_imx->chan_tx);
> + lpi2c_imx->chan_tx = NULL;
> + dev_dbg(dev, "can't get TX channel %d\n", ret);
s/dev_dbg/dev_err_probe
> + return ret;
> + }
> +
> + /* Prepare for RX DMA: */
> + lpi2c_imx->chan_rx = dma_request_chan(dev, "rx");
> + if (IS_ERR(lpi2c_imx->chan_rx)) {
> + ret = PTR_ERR(lpi2c_imx->chan_rx);
> + lpi2c_imx->chan_rx = NULL;
> + dev_dbg(dev, "can't get RX channel %d\n", ret);
Ditto
> + return ret;
> + }
> +
> + lpi2c_imx->can_use_dma = true;
> + return 0;
> +}
> +
> static u32 lpi2c_imx_func(struct i2c_adapter *adapter) {
> return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | @@ -568,12
> +1069,13 @@ static int lpi2c_imx_probe(struct platform_device *pdev)
> struct lpi2c_imx_struct *lpi2c_imx;
> unsigned int temp;
> int irq, ret;
> + struct resource *res;
Usually sort from long to short
>
> lpi2c_imx = devm_kzalloc(&pdev->dev, sizeof(*lpi2c_imx), GFP_KERNEL);
> if (!lpi2c_imx)
> return -ENOMEM;
>
> - lpi2c_imx->base = devm_platform_ioremap_resource(pdev, 0);
> + lpi2c_imx->base = devm_platform_get_and_ioremap_resource(pdev, 0,
> +&res);
> if (IS_ERR(lpi2c_imx->base))
> return PTR_ERR(lpi2c_imx->base);
>
> @@ -587,6 +1089,7 @@ static int lpi2c_imx_probe(struct platform_device
> *pdev)
> lpi2c_imx->adapter.dev.of_node = pdev->dev.of_node;
> strscpy(lpi2c_imx->adapter.name, pdev->name,
> sizeof(lpi2c_imx->adapter.name));
> + lpi2c_imx->phy_addr = (dma_addr_t)res->start;
>
> ret = devm_clk_bulk_get_all(&pdev->dev, &lpi2c_imx->clks);
> if (ret < 0)
> @@ -640,6 +1143,18 @@ static int lpi2c_imx_probe(struct platform_device
> *pdev)
> if (ret == -EPROBE_DEFER)
> goto rpm_disable;
>
> + /* Init DMA */
> + ret = lpi2c_dma_init(&pdev->dev, lpi2c_imx);
> + if (ret) {
> + lpi2c_dma_exit(lpi2c_imx);
> + if (ret == -EPROBE_DEFER)
> + goto rpm_disable;
> + dev_info(&pdev->dev, "LPI2C use pio mode\n");
> + } else
> + dev_info(&pdev->dev, " LPI2C eDMA enabled\n");
> +
Using braces for both branches
See: Documentation/process/coding-style.rst
> + init_completion(&lpi2c_imx->complete);
> +
> ret = i2c_add_adapter(&lpi2c_imx->adapter);
> if (ret)
> goto rpm_disable;
Should we free dma resources here?
> --
> 2.34.1
Regards
Aisheng
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