[PATCH v1 2/3] i2c: imx: separate atomic, dma and non-dma use case

Stefan Eichenberger
2024-07-15T15:18:37Z

From: Stefan Eichenberger <stefan.eichenberger@toradex.com>

Separate the atomic, dma and non-dma use case as a preparation step for
moving the non-dma use case to the isr to avoid rescheduling while a
transfer is in progress.

Signed-off-by: Stefan Eichenberger <stefan.eichenberger@toradex.com>
---
drivers/i2c/busses/i2c-imx.c | 107 +++++++++++++++++++++++------------
1 file changed, 70 insertions(+), 37 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 1add946e3bc20..e242166cb6638 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -1011,6 +1011,43 @@ static int i2c_imx_dma_write(struct imx_i2c_struct *i2c_imx,
return i2c_imx_acked(i2c_imx);
}

+static int i2c_imx_start_read(struct imx_i2c_struct *i2c_imx,
+ struct i2c_msg *msgs, bool atomic,
+ bool use_dma)
+{
+ int result;
+ unsigned int temp = 0;
+
+ /* write slave address */
+ imx_i2c_write_reg(i2c_8bit_addr_from_msg(msgs), i2c_imx, IMX_I2C_I2DR);
+ result = i2c_imx_trx_complete(i2c_imx, atomic);
+ if (result)
+ return result;
+ result = i2c_imx_acked(i2c_imx);
+ if (result)
+ return result;
+
+ dev_dbg(&i2c_imx->adapter.dev, "<%s> setup bus\n", __func__);
+
+ /* setup bus to read data */
+ temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+ temp &= ~I2CR_MTX;
+
+ /*
+ * Reset the I2CR_TXAK flag initially for SMBus block read since the
+ * length is unknown
+ */
+ if (msgs->len - 1)
+ temp &= ~I2CR_TXAK;
+ if (use_dma)
+ temp |= I2CR_DMAEN;
+
+ imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+ imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); /* dummy read */
+
+ return 0;
+}
+
static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
struct i2c_msg *msgs, bool is_lastmsg)
{
@@ -1021,6 +1058,11 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
struct imx_i2c_dma *dma = i2c_imx->dma;
struct device *dev = &i2c_imx->adapter.dev;

+ result = i2c_imx_start_read(i2c_imx, msgs, false, true);
+ if (result)
+ return result;
+
+ dev_dbg(&i2c_imx->adapter.dev, "<%s> read data\n", __func__);

dma->chan_using = dma->chan_rx;
dma->dma_transfer_dir = DMA_DEV_TO_MEM;
@@ -1131,50 +1173,24 @@ static int i2c_imx_write(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs,
return 0;
}

+static int i2c_imx_atomic_write(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
+{
+ return i2c_imx_write(i2c_imx, msgs, true);
+}
+
static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs,
bool is_lastmsg, bool atomic)
{
int i, result;
unsigned int temp;
int block_data = msgs->flags & I2C_M_RECV_LEN;
- int use_dma = i2c_imx->dma && msgs->flags & I2C_M_DMA_SAFE &&
- msgs->len >= DMA_THRESHOLD && !block_data;

- dev_dbg(&i2c_imx->adapter.dev,
- "<%s> write slave address: addr=0x%x\n",
- __func__, i2c_8bit_addr_from_msg(msgs));
-
- /* write slave address */
- imx_i2c_write_reg(i2c_8bit_addr_from_msg(msgs), i2c_imx, IMX_I2C_I2DR);
- result = i2c_imx_trx_complete(i2c_imx, atomic);
+ result = i2c_imx_start_read(i2c_imx, msgs, atomic, false);
if (result)
return result;
- result = i2c_imx_acked(i2c_imx);
- if (result)
- return result;
-
- dev_dbg(&i2c_imx->adapter.dev, "<%s> setup bus\n", __func__);
-
- /* setup bus to read data */
- temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
- temp &= ~I2CR_MTX;
-
- /*
- * Reset the I2CR_TXAK flag initially for SMBus block read since the
- * length is unknown
- */
- if ((msgs->len - 1) || block_data)
- temp &= ~I2CR_TXAK;
- if (use_dma)
- temp |= I2CR_DMAEN;
- 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__);

- if (use_dma)
- return i2c_imx_dma_read(i2c_imx, msgs, is_lastmsg);
-
/* read data */
for (i = 0; i < msgs->len; i++) {
u8 len = 0;
@@ -1241,6 +1257,12 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs,
return 0;
}

+static int i2c_imx_atomic_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs,
+ bool is_lastmsg)
+{
+ return i2c_imx_read(i2c_imx, msgs, is_lastmsg, true);
+}
+
static int i2c_imx_xfer_common(struct i2c_adapter *adapter,
struct i2c_msg *msgs, int num, bool atomic)
{
@@ -1248,6 +1270,7 @@ static int i2c_imx_xfer_common(struct i2c_adapter *adapter,
int result;
bool is_lastmsg = false;
struct imx_i2c_struct *i2c_imx = i2c_get_adapdata(adapter);
+ int use_dma = 0;

/* Start I2C transfer */
result = i2c_imx_start(i2c_imx, atomic);
@@ -1300,15 +1323,25 @@ static int i2c_imx_xfer_common(struct i2c_adapter *adapter,
(temp & I2SR_SRW ? 1 : 0), (temp & I2SR_IIF ? 1 : 0),
(temp & I2SR_RXAK ? 1 : 0));
#endif
+
+ use_dma = i2c_imx->dma && msgs[i].len >= DMA_THRESHOLD &&
+ msgs[i].flags & I2C_M_DMA_SAFE;
if (msgs[i].flags & I2C_M_RD) {
- result = i2c_imx_read(i2c_imx, &msgs[i], is_lastmsg, atomic);
+ int block_data = msgs->flags & I2C_M_RECV_LEN;
+
+ if (atomic)
+ result = i2c_imx_atomic_read(i2c_imx, &msgs[i], is_lastmsg);
+ else if (use_dma && !block_data)
+ result = i2c_imx_dma_read(i2c_imx, &msgs[i], is_lastmsg);
+ else
+ result = i2c_imx_read(i2c_imx, &msgs[i], is_lastmsg, false);
} else {
- if (!atomic &&
- i2c_imx->dma && msgs[i].len >= DMA_THRESHOLD &&
- msgs[i].flags & I2C_M_DMA_SAFE)
+ if (atomic)
+ result = i2c_imx_atomic_write(i2c_imx, &msgs[i]);
+ else if (use_dma)
result = i2c_imx_dma_write(i2c_imx, &msgs[i]);
else
- result = i2c_imx_write(i2c_imx, &msgs[i], atomic);
+ result = i2c_imx_write(i2c_imx, &msgs[i], false);
}
if (result)
goto fail0;
--
2.43.0