RE: [PATCH 11/11] i2c: imx-lpi2c: add edma mode support

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> From: Clark Wang <xiaoning.wang@xxxxxxx>
> Sent: Wednesday, March 17, 2021 2:54 PM
> 
> Add eDMA receive and send mode support.
> Support to read and write data larger than 256 bytes in one frame.
> 
> Signed-off-by: Clark Wang <xiaoning.wang@xxxxxxx>
> Reviewed-by: Li Jun <jun.li@xxxxxxx>
> ---
>  drivers/i2c/busses/i2c-imx-lpi2c.c | 291 ++++++++++++++++++++++++++++-

Pease update dt-binding first

>  1 file changed, 289 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c
> b/drivers/i2c/busses/i2c-imx-lpi2c.c
> index 1e26672d47bf..6d920bf0dbd4 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>
> @@ -31,6 +33,7 @@
>  #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 */
> @@ -72,11 +75,15 @@
>  #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	24 / 59
>  #define CHUNK_DATA	256
> 
>  #define I2C_PM_TIMEOUT		1000 /* ms */
> +#define I2C_DMA_THRESHOLD	16 /* bytes */
> +#define I2C_USE_PIO		(-150)

Can you clarify a bit why need using this strange value?

> 
>  enum lpi2c_imx_mode {
>  	STANDARD,	/* <=100Kbps */
> @@ -95,6 +102,7 @@ enum lpi2c_imx_pincfg {
> 
>  struct lpi2c_imx_struct {
>  	struct i2c_adapter	adapter;
> +	resource_size_t		phy_addr;
>  	int			irq;
>  	struct clk		*clk_per;
>  	struct clk		*clk_ipg;
> @@ -114,6 +122,17 @@ struct lpi2c_imx_struct {
>  	struct pinctrl *pinctrl;
>  	struct pinctrl_state *pinctrl_pins_default;
>  	struct pinctrl_state *pinctrl_pins_gpio;
> +
> +	bool			can_use_dma;
> +	bool			using_dma;
> +	bool			xferred;
> +	struct i2c_msg		*msg;
> +	dma_addr_t		dma_addr;
> +	struct dma_chan		*dma_tx;
> +	struct dma_chan		*dma_rx;
> +	enum dma_data_direction dma_direction;
> +	u8			*dma_buf;
> +	unsigned int		dma_len;
>  };
> 
>  static void lpi2c_imx_intctrl(struct lpi2c_imx_struct *lpi2c_imx, @@ -289,6
> +308,9 @@ static int lpi2c_imx_master_enable(struct lpi2c_imx_struct
> *lpi2c_imx)
>  	if (ret)
>  		goto rpm_put;
> 
> +	if (lpi2c_imx->can_use_dma)
> +		writel(MDER_TDDE | MDER_RDDE, lpi2c_imx->base + LPI2C_MDER);
> +
>  	temp = readl(lpi2c_imx->base + LPI2C_MCR);
>  	temp |= MCR_MEN;
>  	writel(temp, lpi2c_imx->base + LPI2C_MCR); @@ -462,6 +484,154 @@
> static void lpi2c_imx_read(struct lpi2c_imx_struct *lpi2c_imx,
>  	lpi2c_imx_intctrl(lpi2c_imx, MIER_RDIE | MIER_NDIE);  }
> 
> +static void lpi2c_dma_unmap(struct lpi2c_imx_struct *lpi2c_imx) {
> +	struct dma_chan *chan = lpi2c_imx->dma_direction ==
> DMA_FROM_DEVICE
> +				? lpi2c_imx->dma_rx : lpi2c_imx->dma_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_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_all(lpi2c_imx->dma_rx);
> +	else if (lpi2c_imx->dma_direction == DMA_TO_DEVICE)
> +		dmaengine_terminate_all(lpi2c_imx->dma_tx);
> +
> +	lpi2c_dma_unmap(lpi2c_imx);
> +}
> +
> +static void lpi2c_dma_callback(void *data) {
> +	struct lpi2c_imx_struct *lpi2c_imx = (struct lpi2c_imx_struct *)data;
> +
> +	lpi2c_dma_unmap(lpi2c_imx);
> +	writel(GEN_STOP << 8, lpi2c_imx->base + LPI2C_MTDR);
> +	lpi2c_imx->xferred = true;
> +
> +	complete(&lpi2c_imx->complete);
> +}
> +
> +static int lpi2c_dma_submit(struct lpi2c_imx_struct *lpi2c_imx,
> +			   struct i2c_msg *msg)
> +{
> +	bool read = msg->flags & I2C_M_RD;
> +	enum dma_data_direction dir = read ? DMA_FROM_DEVICE :
> DMA_TO_DEVICE;
> +	struct dma_chan *chan = read ? lpi2c_imx->dma_rx : lpi2c_imx->dma_tx;
> +	struct dma_async_tx_descriptor *txdesc;
> +	dma_cookie_t cookie;
> +
> +	lpi2c_imx->dma_len = read ? msg->len - 1 : msg->len;
> +	lpi2c_imx->msg = msg;
> +	lpi2c_imx->dma_direction = dir;
> +
> +	if (IS_ERR(chan))
> +		return PTR_ERR(chan);
> +
> +	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;
> +	}
> +
> +	txdesc = 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 (!txdesc) {
> +		dev_err(&lpi2c_imx->adapter.dev, "dma prep slave sg failed, use
> pio\n");
> +		lpi2c_cleanup_dma(lpi2c_imx);
> +		return -EINVAL;
> +	}
> +
> +	reinit_completion(&lpi2c_imx->complete);
> +	txdesc->callback = lpi2c_dma_callback;
> +	txdesc->callback_param = (void *)lpi2c_imx;
> +
> +	cookie = dmaengine_submit(txdesc);
> +	if (dma_submit_error(cookie)) {
> +		dev_err(&lpi2c_imx->adapter.dev, "submitting dma failed, use
> pio\n");
> +		lpi2c_cleanup_dma(lpi2c_imx);
> +		return -EINVAL;
> +	}
> +
> +	lpi2c_imx_intctrl(lpi2c_imx, MIER_NDIE);
> +
> +	dma_async_issue_pending(chan);
> +
> +	return 0;
> +}
> +
> +static bool is_use_dma(struct lpi2c_imx_struct *lpi2c_imx, struct
> +i2c_msg *msg) {
> +	if (!lpi2c_imx->can_use_dma)
> +		return false;
> +
> +	if (msg->len < I2C_DMA_THRESHOLD)
> +		return false;
> +
> +	return true;
> +}
> +
> +static int lpi2c_imx_push_rx_cmd(struct lpi2c_imx_struct *lpi2c_imx,
> +				 struct i2c_msg *msg)
> +{
> +	unsigned int temp, rx_remain;
> +	unsigned long orig_jiffies = jiffies;
> +
> +	if ((msg->flags & I2C_M_RD)) {
> +		rx_remain = msg->len;
> +		do {
> +			temp = rx_remain > CHUNK_DATA ?
> +				CHUNK_DATA - 1 : rx_remain - 1;
> +			temp |= (RECV_DATA << 8);
> +			while ((readl(lpi2c_imx->base + LPI2C_MFSR) & 0xff) > 2) {
> +				if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(1000))) {
> +					dev_dbg(&lpi2c_imx->adapter.dev, "txfifo empty
> timeout\n");
> +					if (lpi2c_imx->adapter.bus_recovery_info)
> +						i2c_recover_bus(&lpi2c_imx->adapter);
> +					return -ETIMEDOUT;
> +				}
> +				schedule();
> +			}
> +			writel(temp, lpi2c_imx->base + LPI2C_MTDR);
> +			rx_remain = rx_remain - (temp & 0xff) - 1;
> +		} while (rx_remain > 0);
> +	}
> +
> +	return 0;
> +}
> +
> +static int lpi2c_dma_xfer(struct lpi2c_imx_struct *lpi2c_imx,
> +			   struct i2c_msg *msg)
> +{
> +	int result;
> +
> +	result = lpi2c_dma_submit(lpi2c_imx, msg);
> +	if (!result) {
> +		result = lpi2c_imx_push_rx_cmd(lpi2c_imx, msg);
> +		if (result)
> +			return result;
> +		result = lpi2c_imx_msg_complete(lpi2c_imx);
> +		return result;
> +	}
> +
> +	/* DMA xfer failed, try to use PIO, clean up dma things */
> +	i2c_put_dma_safe_msg_buf(lpi2c_imx->dma_buf, lpi2c_imx->msg,
> +				 lpi2c_imx->xferred);
> +	lpi2c_cleanup_dma(lpi2c_imx);
> +
> +	return I2C_USE_PIO;
> +}
> +
>  static int lpi2c_imx_xfer(struct i2c_adapter *adapter,
>  			  struct i2c_msg *msgs, int num)
>  {
> @@ -474,6 +644,9 @@ static int lpi2c_imx_xfer(struct i2c_adapter *adapter,
>  		return result;
> 
>  	for (i = 0; i < num; i++) {
> +		lpi2c_imx->xferred = false;
> +		lpi2c_imx->using_dma = false;
> +
>  		result = lpi2c_imx_start(lpi2c_imx, &msgs[i]);
>  		if (result)
>  			goto disable;
> @@ -482,9 +655,24 @@ static int lpi2c_imx_xfer(struct i2c_adapter *adapter,
>  		if (num == 1 && msgs[0].len == 0)
>  			goto stop;
> 
> +		if (is_use_dma(lpi2c_imx, &msgs[i])) {
> +			lpi2c_imx->using_dma = true;
> +
> +			writel(0x1, lpi2c_imx->base + LPI2C_MFCR);
> +
> +			lpi2c_imx->dma_buf = i2c_get_dma_safe_msg_buf(&msgs[i],
> +							    I2C_DMA_THRESHOLD);
> +			if (lpi2c_imx->dma_buf) {
> +				result = lpi2c_dma_xfer(lpi2c_imx, &msgs[i]);
> +				if (result != I2C_USE_PIO)
> +					goto stop;
> +			}
> +		}
> +
> +		lpi2c_imx->using_dma = false;
>  		lpi2c_imx->delivered = 0;
>  		lpi2c_imx->msglen = msgs[i].len;
> -		init_completion(&lpi2c_imx->complete);
> +		reinit_completion(&lpi2c_imx->complete);
> 
>  		if (msgs[i].flags & I2C_M_RD)
>  			lpi2c_imx_read(lpi2c_imx, &msgs[i]); @@ -503,7 +691,16 @@
> static int lpi2c_imx_xfer(struct i2c_adapter *adapter,
>  	}
> 
>  stop:
> -	lpi2c_imx_stop(lpi2c_imx);
> +	if (!lpi2c_imx->using_dma)
> +		lpi2c_imx_stop(lpi2c_imx);
> +	else {
> +		i2c_put_dma_safe_msg_buf(lpi2c_imx->dma_buf, lpi2c_imx->msg,
> +					 lpi2c_imx->xferred);
> +		if (result) {
> +			lpi2c_cleanup_dma(lpi2c_imx);
> +			writel(GEN_STOP << 8, lpi2c_imx->base + LPI2C_MTDR);
> +		}
> +	}
> 
>  	temp = readl(lpi2c_imx->base + LPI2C_MSR);
>  	if ((temp & MSR_NDF) && !result)
> @@ -528,6 +725,10 @@ static irqreturn_t lpi2c_imx_isr(int irq, void *dev_id)
>  	temp = readl(lpi2c_imx->base + LPI2C_MSR);
> 
>  	if (temp & MSR_NDF) {
> +		if (lpi2c_imx->using_dma) {
> +			lpi2c_cleanup_dma(lpi2c_imx);
> +			writel(GEN_STOP << 8, lpi2c_imx->base + LPI2C_MTDR);
> +		}
>  		complete(&lpi2c_imx->complete);
>  		goto ret;
>  	}
> @@ -623,20 +824,94 @@ static const struct of_device_id
> lpi2c_imx_of_match[] = {  };  MODULE_DEVICE_TABLE(of,
> lpi2c_imx_of_match);
> 
> +static void lpi2c_dma_exit(struct lpi2c_imx_struct *lpi2c_imx) {
> +	if (lpi2c_imx->dma_rx) {
> +		dma_release_channel(lpi2c_imx->dma_rx);
> +		lpi2c_imx->dma_rx = NULL;
> +	}
> +
> +	if (lpi2c_imx->dma_tx) {
> +		dma_release_channel(lpi2c_imx->dma_tx);
> +		lpi2c_imx->dma_tx = NULL;
> +	}
> +}
> +
> +static int lpi2c_dma_init(struct device *dev,
> +			  struct lpi2c_imx_struct *lpi2c_imx) {
> +	int ret;
> +	struct dma_slave_config dma_sconfig;
> +
> +	/* Prepare for TX DMA: */
> +	lpi2c_imx->dma_tx = dma_request_chan(dev, "tx");
> +	if (IS_ERR(lpi2c_imx->dma_tx)) {
> +		ret = PTR_ERR(lpi2c_imx->dma_tx);
> +		dev_err(dev, "can't get the TX DMA channel, error %d!\n", ret);
> +		lpi2c_imx->dma_tx = NULL;
> +		goto err;
> +	}
> +
> +	dma_sconfig.dst_addr = lpi2c_imx->phy_addr + LPI2C_MTDR;
> +	dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
> +	dma_sconfig.dst_maxburst = 1;
> +	dma_sconfig.direction = DMA_MEM_TO_DEV;
> +	ret = dmaengine_slave_config(lpi2c_imx->dma_tx, &dma_sconfig);
> +	if (ret < 0) {
> +		dev_err(dev, "can't configure tx channel (%d)\n", ret);
> +		goto fail_tx;
> +	}
> +
> +	/* Prepare for RX DMA: */
> +	lpi2c_imx->dma_rx = dma_request_chan(dev, "rx");
> +	if (IS_ERR(lpi2c_imx->dma_rx)) {
> +		ret = PTR_ERR(lpi2c_imx->dma_rx);
> +		dev_err(dev, "can't get the RX DMA channel, error %d\n", ret);
> +		lpi2c_imx->dma_rx = NULL;
> +		goto fail_tx;
> +	}
> +
> +	dma_sconfig.src_addr = lpi2c_imx->phy_addr + LPI2C_MRDR;
> +	dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
> +	dma_sconfig.src_maxburst = 1;
> +	dma_sconfig.direction = DMA_DEV_TO_MEM;
> +	ret = dmaengine_slave_config(lpi2c_imx->dma_rx, &dma_sconfig);
> +	if (ret < 0) {
> +		dev_err(dev, "can't configure rx channel (%d)\n", ret);
> +		goto fail_rx;
> +	}
> +
> +	lpi2c_imx->can_use_dma = true;
> +	lpi2c_imx->using_dma = false;
> +
> +	return 0;
> +fail_rx:
> +	dma_release_channel(lpi2c_imx->dma_rx);
> +fail_tx:
> +	dma_release_channel(lpi2c_imx->dma_tx);
> +err:
> +	lpi2c_dma_exit(lpi2c_imx);
> +	lpi2c_imx->can_use_dma = false;
> +	return ret;
> +}
> +
>  static int lpi2c_imx_probe(struct platform_device *pdev)  {
>  	struct lpi2c_imx_struct *lpi2c_imx;
>  	unsigned int temp;
>  	int ret;
> +	struct resource *res;
> 
>  	lpi2c_imx = devm_kzalloc(&pdev->dev, sizeof(*lpi2c_imx), GFP_KERNEL);
>  	if (!lpi2c_imx)
>  		return -ENOMEM;
> 
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	lpi2c_imx->base = devm_platform_ioremap_resource(pdev, 0);
>  	if (IS_ERR(lpi2c_imx->base))
>  		return PTR_ERR(lpi2c_imx->base);
> 
> +	lpi2c_imx->phy_addr = (dma_addr_t)res->start;
>  	lpi2c_imx->irq = platform_get_irq(pdev, 0);
>  	if (lpi2c_imx->irq < 0)
>  		return lpi2c_imx->irq;
> @@ -691,6 +966,18 @@ static int lpi2c_imx_probe(struct platform_device
> *pdev)
>  	if (ret == -EPROBE_DEFER)
>  		goto rpm_disable;
> 
> +	/* Init DMA */
> +	lpi2c_imx->dma_direction = DMA_NONE;
> +	lpi2c_imx->dma_rx = lpi2c_imx->dma_tx = NULL;

Unnecessary line

> +	ret = lpi2c_dma_init(&pdev->dev, lpi2c_imx);
> +	if (ret) {
> +		dev_err_probe(&pdev->dev, ret, "dma setup error %d, use pio\n",
> ret);
> +		if (ret == -EPROBE_DEFER)
> +			goto rpm_disable;
> +	}
> +
> +	init_completion(&lpi2c_imx->complete);
> +
>  	ret = i2c_add_adapter(&lpi2c_imx->adapter);
>  	if (ret)
>  		goto rpm_disable;
> --
> 2.25.1





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