media: imx274: add helper to read multibyte registers

Currently 2-bytes and 3-bytes registers are read one byte at a time,
doing the needed shift & mask each time.

Replace all of this code by a unique helper function that calls
regmap_bulk_read(), which has two advantages:
 - reads all the bytes in a unique I2C transaction
 - simplifies code to read multibyte registers

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

diff --git a/drivers/media/i2c/imx274.c b/drivers/media/i2c/imx274.c
index 07bc41f537c55ea5e922496eeefb0a652c8b8772..783277068b45cd7c5a2d0e11dce485666d59fe88 100644 (file)
--- a/drivers/media/i2c/imx274.c
+++ b/drivers/media/i2c/imx274.c
@@ -659,6 +659,41 @@ static inline int imx274_write_reg(struct stimx274 *priv, u16 addr, u8 val)
        return err;
 }
 
+/**
+ * Read a multibyte register.
+ *
+ * Uses a bulk read where possible.
+ *
+ * @priv: Pointer to device structure
+ * @addr: Address of the LSB register.  Other registers must be
+ *        consecutive, least-to-most significant.
+ * @val: Pointer to store the register value (cpu endianness)
+ * @nbytes: Number of bytes to read (range: [1..3]).
+ *          Other bytes are zet to 0.
+ *
+ * Return: 0 on success, errors otherwise
+ */
+static int imx274_read_mbreg(struct stimx274 *priv, u16 addr, u32 *val,
+                            size_t nbytes)
+{
+       __le32 val_le = 0;
+       int err;
+
+       err = regmap_bulk_read(priv->regmap, addr, &val_le, nbytes);
+       if (err) {
+               dev_err(&priv->client->dev,
+                       "%s : i2c bulk read failed, %x (%zu bytes)\n",
+                       __func__, addr, nbytes);
+       } else {
+               *val = le32_to_cpu(val_le);
+               dev_dbg(&priv->client->dev,
+                       "%s : addr 0x%x, val=0x%x (%zu bytes)\n",
+                       __func__, addr, *val, nbytes);
+       }
+
+       return err;
+}
+
 /**
  * Write a multibyte register.
  *
@@ -1377,37 +1412,17 @@ fail:
 static int imx274_get_frame_length(struct stimx274 *priv, u32 *val)
 {
        int err;
-       u16 svr;
+       u32 svr;
        u32 vmax;
-       u8 reg_val[3];
 
-       /* svr */
-       err = imx274_read_reg(priv, IMX274_SVR_REG_LSB, &reg_val[0]);
+       err = imx274_read_mbreg(priv, IMX274_SVR_REG_LSB, &svr, 2);
        if (err)
                goto fail;
 
-       err = imx274_read_reg(priv, IMX274_SVR_REG_MSB, &reg_val[1]);
+       err = imx274_read_mbreg(priv, IMX274_VMAX_REG_3, &vmax, 3);
        if (err)
                goto fail;
 
-       svr = (reg_val[1] << IMX274_SHIFT_8_BITS) + reg_val[0];
-
-       /* vmax */
-       err = imx274_read_reg(priv, IMX274_VMAX_REG_3, &reg_val[0]);
-       if (err)
-               goto fail;
-
-       err = imx274_read_reg(priv, IMX274_VMAX_REG_2, &reg_val[1]);
-       if (err)
-               goto fail;
-
-       err = imx274_read_reg(priv, IMX274_VMAX_REG_1, &reg_val[2]);
-       if (err)
-               goto fail;
-
-       vmax = ((reg_val[2] & IMX274_MASK_LSB_3_BITS) << IMX274_SHIFT_16_BITS)
-               + (reg_val[1] << IMX274_SHIFT_8_BITS) + reg_val[0];
-
        *val = vmax * (svr + 1);
 
        return 0;
@@ -1588,8 +1603,7 @@ fail:
 static int imx274_set_exposure(struct stimx274 *priv, int val)
 {
        int err;
-       u16 hmax;
-       u8 reg_val[2];
+       u32 hmax;
        u32 coarse_time; /* exposure time in unit of line (HMAX)*/
 
        dev_dbg(&priv->client->dev,
@@ -1597,14 +1611,10 @@ static int imx274_set_exposure(struct stimx274 *priv, int val)
 
        /* step 1: convert input exposure_time (val) into number of 1[HMAX] */
 
-       /* obtain HMAX value */
-       err = imx274_read_reg(priv, IMX274_HMAX_REG_LSB, &reg_val[0]);
-       if (err)
-               goto fail;
-       err = imx274_read_reg(priv, IMX274_HMAX_REG_MSB, &reg_val[1]);
+       err = imx274_read_mbreg(priv, IMX274_HMAX_REG_LSB, &hmax, 2);
        if (err)
                goto fail;
-       hmax = (reg_val[1] << IMX274_SHIFT_8_BITS) + reg_val[0];
+
        if (hmax == 0) {
                err = -EINVAL;
                goto fail;
@@ -1739,9 +1749,8 @@ static int imx274_set_frame_interval(struct stimx274 *priv,
 {
        int err;
        u32 frame_length, req_frame_rate;
-       u16 svr;
-       u16 hmax;
-       u8 reg_val[2];
+       u32 svr;
+       u32 hmax;
 
        dev_dbg(&priv->client->dev, "%s: input frame interval = %d / %d",
                __func__, frame_interval.numerator,
@@ -1769,25 +1778,17 @@ static int imx274_set_frame_interval(struct stimx274 *priv,
         * frame_length (i.e. VMAX) = (frame_interval) x 72M /(SVR+1) / HMAX
         */
 
-       /* SVR */
-       err = imx274_read_reg(priv, IMX274_SVR_REG_LSB, &reg_val[0]);
+       err = imx274_read_mbreg(priv, IMX274_SVR_REG_LSB, &svr, 2);
        if (err)
                goto fail;
-       err = imx274_read_reg(priv, IMX274_SVR_REG_MSB, &reg_val[1]);
-       if (err)
-               goto fail;
-       svr = (reg_val[1] << IMX274_SHIFT_8_BITS) + reg_val[0];
+
        dev_dbg(&priv->client->dev,
                "%s : register SVR = %d\n", __func__, svr);
 
-       /* HMAX */
-       err = imx274_read_reg(priv, IMX274_HMAX_REG_LSB, &reg_val[0]);
+       err = imx274_read_mbreg(priv, IMX274_HMAX_REG_LSB, &hmax, 2);
        if (err)
                goto fail;
-       err = imx274_read_reg(priv, IMX274_HMAX_REG_MSB, &reg_val[1]);
-       if (err)
-               goto fail;
-       hmax = (reg_val[1] << IMX274_SHIFT_8_BITS) + reg_val[0];
+
        dev_dbg(&priv->client->dev,
                "%s : register HMAX = %d\n", __func__, hmax);