linux-kernel - [PATCH v7 3/3] media: ov8856: Implement sensor module revision identification

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Date:   Tue,  5 May 2020 12:01:32 +0200
From:   Robert Foss <robert.foss@...aro.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@....fi>,
        Marco Felsch <m.felsch@...gutronix.de>,
        Maxime Ripard <maxime@...no.tech>, linux-media@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Cc:     Dongchun Zhu <dongchun.zhu@...iatek.com>,
        Fabio Estevam <festevam@...il.com>,
        Tomasz Figa <tfiga@...omium.org>, Ben Kao <ben.kao@...el.com>,
        Robert Foss <robert.foss@...aro.org>
Subject: [PATCH v7 3/3] media: ov8856: Implement sensor module revision identification

Query the sensor for its module revision, and compare it
to known revisions.

Currently 2A and 1B revision indentification is supported.

Signed-off-by: Robert Foss <robert.foss@...aro.org>
---

- Changes since v3:
  * Actually add module revision 2A

- Changes since v2:
  * Add module revision 2A
  * Sakari: Remove ov8856_check_revision()
  * Sakari: Stop EEPROM streaming mode

 drivers/media/i2c/ov8856.c | 53 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/drivers/media/i2c/ov8856.c b/drivers/media/i2c/ov8856.c
index e6418a79801e..3c82c3e588d7 100644
--- a/drivers/media/i2c/ov8856.c
+++ b/drivers/media/i2c/ov8856.c
@@ -32,6 +32,19 @@
 #define OV8856_MODE_STANDBY		0x00
 #define OV8856_MODE_STREAMING		0x01
 
+/* module revisions */
+#define OV8856_2A_MODULE		0x01
+#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
@@ -1152,6 +1165,46 @@ static int ov8856_identify_module(struct ov8856 *ov8856)
 		return -ENXIO;
 	}
 
+	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) {
+		dev_err(&client->dev, "failed to set otp mode");
+		return ret;
+	}
+
+	ret = ov8856_write_reg(ov8856, OV8856_OTP_LOAD_CTRL,
+			       OV8856_REG_VALUE_08BIT,
+			       OV8856_OTP_LOAD_CTRL_ENABLE);
+	if (ret) {
+		dev_err(&client->dev, "failed to enable load control");
+		return ret;
+	}
+
+	ret = ov8856_read_reg(ov8856, OV8856_MODULE_REVISION,
+			      OV8856_REG_VALUE_08BIT, &val);
+	if (ret) {
+		dev_err(&client->dev, "failed to read module revision");
+		return ret;
+	}
+
+	dev_info(&client->dev, "OV8856 revision %x (%s) at address 0x%02x\n",
+		val,
+		val == OV8856_2A_MODULE ? "2A" :
+		val == OV8856_1B_MODULE ? "1B" : "unknown revision",
+		client->addr);
+
+	ret = ov8856_write_reg(ov8856, OV8856_REG_MODE_SELECT,
+			       OV8856_REG_VALUE_08BIT, OV8856_MODE_STANDBY);
+	if (ret) {
+		dev_err(&client->dev, "failed to exit streaming mode");
+		return ret;
+	}
+
 	return 0;
 }
 
-- 
2.25.1