Re: [PATCH v4 1/2] i2c: add DMA support for freescale i2c driver

From: sourav
Date: Fri Apr 04 2014 - 05:50:37 EST

Hi,
On Friday 04 April 2014 08:11 AM, Yuan Yao wrote:
Add dma support for i2c. This function depend on DMA driver.
You can turn on it by write both the dmas and dma-name properties in dts node.

Signed-off-by: Yuan Yao<yao.yuan@xxxxxxxxxxxxx>
---
drivers/i2c/busses/i2c-imx.c | 372 +++++++++++++++++++++++++++++++++++++------
1 file changed, 319 insertions(+), 53 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index db895fb..3d63b35 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -37,22 +37,27 @@
/** Includes *******************************************************************
*******************************************************************************/

-#include<linux/init.h>
-#include<linux/kernel.h>
-#include<linux/module.h>
+#include<linux/clk.h>
+#include<linux/completion.h>
+#include<linux/delay.h>
+#include<linux/dma-mapping.h>
+#include<linux/dmaengine.h>
+#include<linux/dmapool.h>
#include<linux/errno.h>
#include<linux/err.h>
#include<linux/interrupt.h>
-#include<linux/delay.h>
#include<linux/i2c.h>
+#include<linux/init.h>
#include<linux/io.h>
-#include<linux/sched.h>
-#include<linux/platform_device.h>
-#include<linux/clk.h>
-#include<linux/slab.h>
+#include<linux/kernel.h>
+#include<linux/module.h>
#include<linux/of.h>
#include<linux/of_device.h>
+#include<linux/of_dma.h>
#include<linux/platform_data/i2c-imx.h>
+#include<linux/platform_device.h>
+#include<linux/sched.h>
+#include<linux/slab.h>

/** Defines ********************************************************************
*******************************************************************************/
@@ -63,6 +68,10 @@
/* Default value */
#define IMX_I2C_BIT_RATE 100000 /* 100kHz */

+/* enable DMA if transfer byte size is bigger than this threshold */
+#define IMX_I2C_DMA_THRESHOLD 16
+#define IMX_I2C_DMA_TIMEOUT 1000
+
/* IMX I2C registers:
* the I2C register offset is different between SoCs,
* to provid support for all these chips, split the
@@ -88,6 +97,7 @@
#define I2SR_IBB 0x20
#define I2SR_IAAS 0x40
#define I2SR_ICF 0x80
+#define I2CR_DMAEN 0x02
#define I2CR_RSTA 0x04
#define I2CR_TXAK 0x08
#define I2CR_MTX 0x10
@@ -174,6 +184,17 @@ struct imx_i2c_hwdata {
unsigned i2cr_ien_opcode;
};

+struct imx_i2c_dma {
+ struct dma_chan *chan_tx;
+ struct dma_chan *chan_rx;
+ struct dma_chan *chan_using;
+ struct completion cmd_complete;
+ dma_addr_t dma_buf;
+ unsigned int dma_len;
+ unsigned int dma_transfer_dir;
+ unsigned int dma_data_dir;
+};
+
struct imx_i2c_struct {
struct i2c_adapter adapter;
struct clk *clk;
@@ -184,6 +205,8 @@ struct imx_i2c_struct {
int stopped;
unsigned int ifdr; /* IMX_I2C_IFDR */
const struct imx_i2c_hwdata *hwdata;
+
+ struct imx_i2c_dma *dma;
};

static const struct imx_i2c_hwdata imx1_i2c_hwdata = {
@@ -254,6 +277,132 @@ static inline unsigned char imx_i2c_read_reg(struct imx_i2c_struct *i2c_imx,
return readb(i2c_imx->base + (reg<< i2c_imx->hwdata->regshift));
}

+/* Functions for DMA support */
+static int i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,
+ dma_addr_t phy_addr)
+{
+ struct imx_i2c_dma *dma;
+ struct dma_slave_config dma_sconfig;
+ struct device *dev =&i2c_imx->adapter.dev;
+ int ret;
+
+ dma = devm_kzalloc(dev, sizeof(struct imx_i2c_dma), GFP_KERNEL);
+ if (!dma) {
+ dev_info(dev, "can't allocate DMA struct\n");
+ return -ENOMEM;
+ }
+
+ dma->chan_tx = dma_request_slave_channel(dev, "tx");
+ return 0;
?? Looks to be some leftover?
+ if (!dma->chan_tx) {
+ dev_info(dev, "DMA tx channel request failed\n");
+ ret = -ENODEV;
+ goto fail_al;
+ }
+
+ dma_sconfig.dst_addr = phy_addr +
+ (IMX_I2C_I2DR<< i2c_imx->hwdata->regshift);
+ 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(dma->chan_tx,&dma_sconfig);
+ if (ret< 0) {
+ dev_info(dev, "DMA slave config failed, err = %d\n", ret);
+ goto fail_tx;
+ }
+
+ dma->chan_rx = dma_request_slave_channel(dev, "rx");
+ if (!dma->chan_rx) {
+ dev_info(dev, "DMA rx channel request failed\n");
+ ret = -ENODEV;
+ goto fail_tx;
+ }
+
+ dma_sconfig.src_addr = phy_addr +
+ (IMX_I2C_I2DR<< i2c_imx->hwdata->regshift);
+ 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(dma->chan_rx,&dma_sconfig);
+ if (ret< 0) {
+ dev_info(dev, "DMA slave config failed, err = %d\n", ret);
+ goto fail_rx;
+ }
+
+ i2c_imx->dma = dma;
+
+ init_completion(&dma->cmd_complete);
+
+ return 0;
+
+fail_rx:
+ dma_release_channel(dma->chan_rx);
+fail_tx:
+ dma_release_channel(dma->chan_tx);
+fail_al:
+ devm_kfree(dev, dma);
+
+ return ret;
+}
+
+static void i2c_imx_dma_callback(void *arg)
+{
+ struct imx_i2c_struct *i2c_imx = (struct imx_i2c_struct *)arg;
+ struct imx_i2c_dma *dma = i2c_imx->dma;
+
+ dma_unmap_single(dma->chan_using->device->dev, dma->dma_buf,
+ dma->dma_len, dma->dma_data_dir);
+ complete(&dma->cmd_complete);
+}
+
+static int i2c_imx_dma_xfer(struct imx_i2c_struct *i2c_imx,
+ struct i2c_msg *msgs)
+{
+ struct imx_i2c_dma *dma = i2c_imx->dma;
+ struct dma_async_tx_descriptor *txdesc;
+ struct device *dev =&i2c_imx->adapter.dev;
+
+ dma->dma_buf = dma_map_single(dma->chan_using->device->dev, msgs->buf,
+ dma->dma_len, dma->dma_data_dir);
+ if (dma_mapping_error(dma->chan_using->device->dev, dma->dma_buf)) {
+ dev_err(dev, "DMA mapping failed\n");
+ return -EINVAL;
+ }
+
+ txdesc = dmaengine_prep_slave_single(dma->chan_using, dma->dma_buf,
+ dma->dma_len, dma->dma_transfer_dir,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ if (!txdesc) {
+ dev_err(dev, "Not able to get desc for DMA xfer\n");
+ dma_unmap_single(dma->chan_using->device->dev, dma->dma_buf,
+ dma->dma_len, dma->dma_data_dir);
+ return -EINVAL;
+ }
+
+ txdesc->callback = i2c_imx_dma_callback;
+ txdesc->callback_param = i2c_imx;
+ dmaengine_submit(txdesc);
+ dma_async_issue_pending(dma->chan_using);
+
+ return 0;
+}
+
+static void i2c_imx_dma_free(struct imx_i2c_struct *i2c_imx)
+{
+ struct imx_i2c_dma *dma = i2c_imx->dma;
+
+ dma->dma_buf = 0;
+ dma->dma_len = 0;
+
+ dma_release_channel(dma->chan_tx);
+ dma->chan_tx = NULL;
+
+ dma_release_channel(dma->chan_rx);
+ dma->chan_rx = NULL;
+
+ dma->chan_using = NULL;
+}
+
/** Functions for IMX I2C adapter driver ***************************************
*******************************************************************************/

@@ -334,6 +483,11 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)

temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK;
imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+
+ temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+ temp&= ~I2CR_DMAEN;
+ imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+
return result;
}

@@ -427,44 +581,101 @@ static irqreturn_t i2c_imx_isr(int irq, void *dev_id)

static int i2c_imx_write(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
{
- int i, result;
+ int i, result, timeout = IMX_I2C_DMA_TIMEOUT;
+ unsigned int temp = 0;
+ struct imx_i2c_dma *dma = i2c_imx->dma;
+ struct device *dev =&i2c_imx->adapter.dev;

- dev_dbg(&i2c_imx->adapter.dev, "<%s> write slave address: addr=0x%x\n",
+ dev_dbg(dev, "<%s> write slave address: addr=0x%x\n",
__func__, msgs->addr<< 1);
+ if (dma&& msgs->len>= IMX_I2C_DMA_THRESHOLD) {
+ reinit_completion(&i2c_imx->dma->cmd_complete);
+ dma->chan_using = dma->chan_tx;
+ dma->dma_transfer_dir = DMA_MEM_TO_DEV;
+ dma->dma_data_dir = DMA_TO_DEVICE;
+ dma->dma_len = msgs->len - 1;
+ result = i2c_imx_dma_xfer(i2c_imx, msgs);
+ if (result)
+ return result;

- /* write slave address */
- imx_i2c_write_reg(msgs->addr<< 1, i2c_imx, IMX_I2C_I2DR);
- result = i2c_imx_trx_complete(i2c_imx);
- if (result)
- return result;
- result = i2c_imx_acked(i2c_imx);
- if (result)
- return result;
- dev_dbg(&i2c_imx->adapter.dev, "<%s> write data\n", __func__);
+ temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+ temp |= I2CR_DMAEN;
+ imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);

- /* write data */
- for (i = 0; i< msgs->len; i++) {
- dev_dbg(&i2c_imx->adapter.dev,
- "<%s> write byte: B%d=0x%X\n",
- __func__, i, msgs->buf[i]);
- imx_i2c_write_reg(msgs->buf[i], i2c_imx, IMX_I2C_I2DR);
+ /* write slave address */
+ imx_i2c_write_reg(msgs->addr<< 1, i2c_imx, IMX_I2C_I2DR);
+ result = wait_for_completion_interruptible_timeout(
+ &i2c_imx->dma->cmd_complete,
+ msecs_to_jiffies(IMX_I2C_DMA_TIMEOUT));
+ if (result<= 0) {
+ dmaengine_terminate_all(dma->chan_using);
+ if (result)
+ return result;
+ else
+ return -ETIMEDOUT;
+ }
+
+ /* waiting for Transfer complete. */
+ while (timeout--) {
+ temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
+ if (temp& I2SR_ICF)
+ break;
+ udelay(10);
+ }
+
+ if (!timeout)
+ return -ETIMEDOUT;
+ temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+ temp&= ~I2CR_DMAEN;
+ imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+
+ /* write the last byte */
+ imx_i2c_write_reg(msgs->buf[msgs->len-1],
+ i2c_imx, IMX_I2C_I2DR);
result = i2c_imx_trx_complete(i2c_imx);
if (result)
return result;
+
+ result = i2c_imx_acked(i2c_imx);
+ if (result)
+ return result;
+ } else {
+ /* write slave address */
+ imx_i2c_write_reg(msgs->addr<< 1, i2c_imx, IMX_I2C_I2DR);
+ result = i2c_imx_trx_complete(i2c_imx);
+ if (result)
+ return result;
+
result = i2c_imx_acked(i2c_imx);
if (result)
return result;
+
+ dev_dbg(dev, "<%s> write data\n", __func__);
+
+ /* write data */
+ for (i = 0; i< msgs->len; i++) {
+ dev_dbg(dev, "<%s> write byte: B%d=0x%X\n",
+ __func__, i, msgs->buf[i]);
+ imx_i2c_write_reg(msgs->buf[i], i2c_imx, IMX_I2C_I2DR);
+ result = i2c_imx_trx_complete(i2c_imx);
+ if (result)
+ return result;
+ result = i2c_imx_acked(i2c_imx);
+ if (result)
+ return result;
+ }
}
return 0;
}

static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
{
- int i, result;
+ int i, result, timeout = IMX_I2C_DMA_TIMEOUT;
unsigned int temp;
+ struct imx_i2c_dma *dma = i2c_imx->dma;
+ struct device *dev =&i2c_imx->adapter.dev;

- dev_dbg(&i2c_imx->adapter.dev,
- "<%s> write slave address: addr=0x%x\n",
+ dev_dbg(dev, "<%s> write slave address: addr=0x%x\n",
__func__, (msgs->addr<< 1) | 0x01);

/* write slave address */
@@ -476,7 +687,7 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
if (result)
return result;

- dev_dbg(&i2c_imx->adapter.dev, "<%s> setup bus\n", __func__);
+ dev_dbg(dev, "<%s> setup bus\n", __func__);

/* setup bus to read data */
temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
@@ -486,35 +697,81 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); /* dummy read */

- dev_dbg(&i2c_imx->adapter.dev, "<%s> read data\n", __func__);
+ dev_dbg(dev, "<%s> read data\n", __func__);

- /* read data */
- for (i = 0; i< msgs->len; i++) {
- result = i2c_imx_trx_complete(i2c_imx);
+ if (dma&& msgs->len>= IMX_I2C_DMA_THRESHOLD) {
+ temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+ temp |= I2CR_DMAEN;
+ imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+
+ reinit_completion(&i2c_imx->dma->cmd_complete);
+ dma->chan_using = dma->chan_rx;
+ dma->dma_transfer_dir = DMA_DEV_TO_MEM;
+ dma->dma_data_dir = DMA_FROM_DEVICE;
+ dma->dma_len = msgs->len - 2;
+ result = i2c_imx_dma_xfer(i2c_imx, msgs);
if (result)
return result;
- if (i == (msgs->len - 1)) {
- /* It must generate STOP before read I2DR to prevent
- controller from generating another clock cycle */
- dev_dbg(&i2c_imx->adapter.dev,
- "<%s> clear MSTA\n", __func__);
- temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
- temp&= ~(I2CR_MSTA | I2CR_MTX);
- imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
- i2c_imx_bus_busy(i2c_imx, 0);
- i2c_imx->stopped = 1;
- } else if (i == (msgs->len - 2)) {
- dev_dbg(&i2c_imx->adapter.dev,
- "<%s> set TXAK\n", __func__);
- temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
- temp |= I2CR_TXAK;
- imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+
+ result = wait_for_completion_interruptible_timeout(
+ &i2c_imx->dma->cmd_complete,
+ msecs_to_jiffies(IMX_I2C_DMA_TIMEOUT));
+ if (result<= 0) {
+ dmaengine_terminate_all(dma->chan_using);
+ if (result)
+ return result;
+ else
+ return -ETIMEDOUT;
}
- msgs->buf[i] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
- dev_dbg(&i2c_imx->adapter.dev,
- "<%s> read byte: B%d=0x%X\n",
- __func__, i, msgs->buf[i]);
+
+ /* waiting for Transfer complete. */
+ while (timeout--) {
+ temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
+ if (temp& I2SR_ICF)
+ break;
+ udelay(10);
+ }
+
+ if(!timeout)
+ return -ETIMEDOUT;
+ temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+ temp&= ~I2CR_DMAEN;
+ imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+ } else {
+ /* read data */
+ for (i = 0; i< msgs->len - 2; i++) {
+ result = i2c_imx_trx_complete(i2c_imx);
+ if (result)
+ return result;
+ msgs->buf[i] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
+ dev_dbg(dev, "<%s> read byte: B%d=0x%X\n",
+ __func__, i, msgs->buf[i]);
+ }
+ result = i2c_imx_trx_complete(i2c_imx);
}
+
+ /* read n-1 byte data */
+ temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+ temp |= I2CR_TXAK;
+ imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+
+ msgs->buf[msgs->len-2] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
+ /* read n byte data */
+ result = i2c_imx_trx_complete(i2c_imx);
+ if (result)
+ return result;
+
+ /*
+ * It must generate STOP before read I2DR to prevent
+ * controller from generating another clock cycle
+ */
+ temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+ temp&= ~(I2CR_MSTA | I2CR_MTX);
+ imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+ i2c_imx_bus_busy(i2c_imx, 0);
+ i2c_imx->stopped = 1;
+ msgs->buf[msgs->len-1] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
+
return 0;
}

@@ -601,6 +858,7 @@ static int i2c_imx_probe(struct platform_device *pdev)
void __iomem *base;
int irq, ret;
u32 bitrate;
+ u32 phy_addr;

dev_dbg(&pdev->dev, "<%s>\n", __func__);

@@ -611,6 +869,7 @@ static int i2c_imx_probe(struct platform_device *pdev)
}

res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ phy_addr = res->start;
base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(base))
return PTR_ERR(base);
@@ -696,6 +955,10 @@ static int i2c_imx_probe(struct platform_device *pdev)
i2c_imx->adapter.name);
dev_info(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n");

+ /* Init DMA config if support*/
+ if (i2c_imx_dma_request(i2c_imx, (dma_addr_t)phy_addr))
+ dev_warn(&pdev->dev, "can't request DMA\n");
+
return 0; /* Return OK */
}

@@ -707,6 +970,9 @@ static int i2c_imx_remove(struct platform_device *pdev)
dev_dbg(&i2c_imx->adapter.dev, "adapter removed\n");
i2c_del_adapter(&i2c_imx->adapter);

+ if (i2c_imx->dma)
+ i2c_imx_dma_free(i2c_imx);
+
/* setup chip registers to defaults */
imx_i2c_write_reg(0, i2c_imx, IMX_I2C_IADR);
imx_i2c_write_reg(0, i2c_imx, IMX_I2C_IFDR);

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/