RE: [PATCH V2 14/18] i2c: imx-lpi2c: add edma mode support

[Clark Wang <xiaoning.wang@nxp.com>]

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> -----Original Message-----
> From: Clark Wang <xiaoning.wang@nxp.com>
> Sent: Tuesday, April 6, 2021 19:33
> To: Aisheng Dong <aisheng.dong@nxp.com>; robh+dt@kernel.org;
> shawnguo@kernel.org; s.hauer@pengutronix.de; festevam@gmail.com
> Cc: kernel@pengutronix.de; dl-linux-imx <linux-imx@nxp.com>; linux-
> i2c@vger.kernel.org; devicetree@vger.kernel.org; linux-arm-
> kernel@lists.infradead.org; linux-kernel@vger.kernel.org
> Subject: [PATCH V2 14/18] i2c: imx-lpi2c: add edma mode support
> 
> 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@nxp.com>
> Reviewed-by: Li Jun <jun.li@nxp.com>
> ---
> V2 changes:
>  - change marco I2C_USE_PIO to DMA_ERR_I2C_USE_PIO. It is a error code
> defined
>    in this driver to

It is an error code defined in this driver to identify the DMA sending
error, then driver will try to use PIO to send data.

Best Regards,
Clark Wang
> ---
>  drivers/i2c/busses/i2c-imx-lpi2c.c | 290 ++++++++++++++++++++++++++++-
>  1 file changed, 288 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c
b/drivers/i2c/busses/i2c-imx-
> lpi2c.c
> index c2f8e49660ea..d1a56d52f19f 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 DMA_ERR_I2C_USE_PIO	(-150)
> 
>  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_dma_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)
>
> (lpi2c_imx->rxfifosize >> 1)) {
> +				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_dma_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 DMA_ERR_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 != DMA_ERR_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;
>  	}
> @@ -623,6 +824,77 @@ 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_clocks_prepare(struct lpi2c_imx_struct *lpi2c_imx)
{
>  	int ret = 0;
> @@ -656,15 +928,18 @@ 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;
> @@ -716,6 +991,17 @@ static int lpi2c_imx_probe(struct platform_device
> *pdev)
>  	if (ret == -EPROBE_DEFER)
>  		goto rpm_disable;
> 
> +	/* Init DMA */
> +	lpi2c_imx->dma_direction = DMA_NONE;
> +	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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