[v2 3/3] media: ov8856: Implement sensor module revision identification

[Robert Foss <robert.foss@xxxxxxxxxx>]

Query the sensor for its module revision, and compare it
to known revisions.
Currently only the '1B' revision has been added.

Signed-off-by: Robert Foss <robert.foss@xxxxxxxxxx>
---
 drivers/media/i2c/ov8856.c | 54 +++++++++++++++++++++++++++++++++-----
 1 file changed, 48 insertions(+), 6 deletions(-)

diff --git a/drivers/media/i2c/ov8856.c b/drivers/media/i2c/ov8856.c
index db61eed223e8..39662d3d86dd 100644
--- a/drivers/media/i2c/ov8856.c
+++ b/drivers/media/i2c/ov8856.c
@@ -34,6 +34,18 @@
 #define OV8856_MODE_STANDBY		0x00
 #define OV8856_MODE_STREAMING		0x01
 
+/* define 1B module revision */
+#define OV8856_1B_MODULE		0x02
+
+/* the OTP read-out buffer is at 0x7000 and 0xf is the offset
+ * of the byte in the OTP that means the module revision
+ */
+#define OV8856_MODULE_REVISION		0x700f
+#define OV8856_OTP_MODE_CTRL		0x3d84
+#define OV8856_OTP_LOAD_CTRL		0x3d81
+#define OV8856_OTP_MODE_AUTO		0x00
+#define OV8856_OTP_LOAD_CTRL_ENABLE	BIT(0)
+
 /* vertical-timings from sensor */
 #define OV8856_REG_VTS			0x380e
 #define OV8856_VTS_MAX			0x7fff
@@ -711,6 +723,25 @@ static int ov8856_test_pattern(struct ov8856 *ov8856, u32 pattern)
 				OV8856_REG_VALUE_08BIT, pattern);
 }
 
+static int ov8856_check_revision(struct ov8856 *ov8856)
+{
+	int ret;
+
+	ret = ov8856_write_reg(ov8856, OV8856_REG_MODE_SELECT,
+			       OV8856_REG_VALUE_08BIT, OV8856_MODE_STREAMING);
+	if (ret)
+		return ret;
+
+	ret = ov8856_write_reg(ov8856, OV8856_OTP_MODE_CTRL,
+			       OV8856_REG_VALUE_08BIT, OV8856_OTP_MODE_AUTO);
+	if (ret)
+		return ret;
+
+	return ov8856_write_reg(ov8856, OV8856_OTP_LOAD_CTRL,
+				OV8856_REG_VALUE_08BIT,
+				OV8856_OTP_LOAD_CTRL_ENABLE);
+}
+
 static int ov8856_set_ctrl(struct v4l2_ctrl *ctrl)
 {
 	struct ov8856 *ov8856 = container_of(ctrl->handler,
@@ -1144,6 +1175,23 @@ static int ov8856_identify_module(struct ov8856 *ov8856)
 		return -ENXIO;
 	}
 
+	/* check sensor hardware revision */
+	ret = ov8856_check_revision(ov8856);
+	if (ret) {
+		dev_err(&client->dev, "failed to check sensor revision");
+		return ret;
+	}
+
+	ret = ov8856_read_reg(ov8856, OV8856_MODULE_REVISION,
+			      OV8856_REG_VALUE_08BIT, &val);
+	if (ret)
+		return ret;
+
+	dev_info(&client->dev, "OV8856 revision %x (%s) at address 0x%02x\n",
+		val,
+		val == OV8856_1B_MODULE ? "1B" : "unknown revision",
+		client->addr);
+
 	return 0;
 }
 
@@ -1254,12 +1302,6 @@ static int ov8856_probe(struct i2c_client *client)
 		return PTR_ERR(ov8856->xvclk);
 	}
 
-	ret = clk_set_rate(ov8856->xvclk, OV8856_XVCLK_24);
-	if (ret < 0) {
-		dev_err(&client->dev, "failed to set xvclk rate (24MHz)\n");
-		return ret;
-	}
-
 	ov8856->reset_gpio = devm_gpiod_get(&client->dev, "reset",
 					       GPIOD_OUT_HIGH);
 	if (IS_ERR(ov8856->reset_gpio)) {
-- 
2.20.1