drivers: media: imx708: Enable long exposure mode

Enable long exposure modes by using the long exposure shift register setting
in the imx708 sensor.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
[sw0312.kim: cherry-pick raspberry pi kernel upstream to support rpi camera module v3]
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Change-Id: I73bfd16537aa7784652f45b9b1f9930677b72304

diff --git a/drivers/media/i2c/imx708.c b/drivers/media/i2c/imx708.c
index 8961ea1..785275c 100644 (file)
--- a/drivers/media/i2c/imx708.c
+++ b/drivers/media/i2c/imx708.c
@@ -44,6 +44,10 @@
 #define IMX708_REG_FRAME_LENGTH                0x0340
 #define IMX708_FRAME_LENGTH_MAX                0xffff
 
+/* Long exposure multiplier */
+#define IMX708_LONG_EXP_SHIFT_MAX      7
+#define IMX708_LONG_EXP_SHIFT_REG      0x3100
+
 /* Exposure control */
 #define IMX708_REG_EXPOSURE            0x0202
 #define IMX708_EXPOSURE_OFFSET         48
@@ -806,6 +810,9 @@ struct imx708 {
 
        /* Rewrite common registers on stream on? */
        bool common_regs_written;
+
+       /* Current long exposure factor in use. Set through V4L2_CID_VBLANK */
+       unsigned int long_exp_shift;
 };
 
 static inline struct imx708 *to_imx708(struct v4l2_subdev *_sd)
@@ -994,7 +1001,8 @@ static int imx708_set_exposure(struct imx708 *imx708, unsigned int val)
         * will automatically divide the medium and short ones by 4,16.
         */
        ret = imx708_write_reg(imx708, IMX708_REG_EXPOSURE,
-                              IMX708_REG_VALUE_16BIT, val);
+                              IMX708_REG_VALUE_16BIT,
+                              val >> imx708->long_exp_shift);
 
        return ret;
 }
@@ -1027,18 +1035,42 @@ static int imx708_set_analogue_gain(struct imx708 *imx708, unsigned int val)
        return ret;
 }
 
+static int imx708_set_frame_length(struct imx708 *imx708, unsigned int val)
+{
+       int ret = 0;
+
+       imx708->long_exp_shift = 0;
+
+       while (val > IMX708_FRAME_LENGTH_MAX) {
+               imx708->long_exp_shift++;
+               val >>= 1;
+       }
+
+       ret = imx708_write_reg(imx708, IMX708_REG_FRAME_LENGTH,
+                              IMX708_REG_VALUE_16BIT, val);
+       if (ret)
+               return ret;
+
+       return imx708_write_reg(imx708, IMX708_LONG_EXP_SHIFT_REG,
+                               IMX708_REG_VALUE_08BIT, imx708->long_exp_shift);
+}
+
 static void imx708_set_framing_limits(struct imx708 *imx708)
 {
        unsigned int hblank;
        const struct imx708_mode *mode = imx708->mode;
 
+       /* Default to no long exposure multiplier */
+       imx708->long_exp_shift = 0;
+
        __v4l2_ctrl_modify_range(imx708->pixel_rate,
                                 mode->pixel_rate, mode->pixel_rate,
                                 1, mode->pixel_rate);
 
        /* Update limits and set FPS to default */
        __v4l2_ctrl_modify_range(imx708->vblank, mode->vblank_min,
-                                IMX708_FRAME_LENGTH_MAX - mode->height,
+                                ((1 << IMX708_LONG_EXP_SHIFT_MAX) *
+                                       IMX708_FRAME_LENGTH_MAX) - mode->height,
                                 1, mode->vblank_default);
 
        /*
@@ -1112,9 +1144,8 @@ static int imx708_set_ctrl(struct v4l2_ctrl *ctrl)
                                       imx708->vflip->val << 1);
                break;
        case V4L2_CID_VBLANK:
-               ret = imx708_write_reg(imx708, IMX708_REG_FRAME_LENGTH,
-                                      IMX708_REG_VALUE_16BIT,
-                                      imx708->mode->height + ctrl->val);
+               ret = imx708_set_frame_length(imx708,
+                                             imx708->mode->height + ctrl->val);
                break;
        case V4L2_CID_NOTIFY_GAINS:
                ret = imx708_write_reg(imx708, IMX708_REG_COLOUR_BALANCE_BLUE,