i2c: imx: separate atomic, dma and non-dma use case

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>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index b39c37acd30e0ebdbc30024cc266b76325c42d4c..9694d5c3d682802251ffcc40238de88b34bc0303 100644 (file)
--- 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_prepare_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_prepare_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_prepare_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;