[PATCH v5 02/14] media: mt9m114: Use aptina-PLL helper to get PLL values

[Hans de Goede <johannes.goede@oss.qualcomm.com>]

Before this change the driver used hardcoded PLL m, n and p values to
achieve a 48MHz pixclock when used with an external clock with a frequency
of 24 MHz.

Use aptina_pll_calculate() to allow the driver to work with different
external clock frequencies. The m, n, and p values will be unchanged
with a 24 MHz extclk and this has also been tested with a 19.2 MHz
clock where m gets increased from 32 to 40.

Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
---
Changes in v5:
- Add a code-comment documenting the PLL chain, this is a verbatim
  copy of Laurent's ASCII-art PLL chain from the mailinglist.
- Use sensor->pll.ext_clock instead of calling clk_get_rate()

Changes in v4:
- After re-reading the docs out_clock_max should be 384MHz and P1 should
  always be 8, adjust the pll-limits accordingly and drop the comment
  about the out_clock_max from the documentation not working

Changes in v3:
- Document that using 768Mhz for out_clock_max does not work

Changes in v2:
- Add select VIDEO_APTINA_PLL to Kconfig
- Use correct aptina_pll_limits
---
 drivers/media/i2c/Kconfig   |  1 +
 drivers/media/i2c/mt9m114.c | 64 +++++++++++++++++++++++++++++++++------------
 2 files changed, 49 insertions(+), 16 deletions(-)

diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
index 4b4db8c4f49657e19018535927eb41f7ad2a4f80..befea5952191184536ad7d7e5c81f567826d8aa7 100644
--- a/drivers/media/i2c/Kconfig
+++ b/drivers/media/i2c/Kconfig
@@ -305,6 +305,7 @@ config VIDEO_MT9M111
 config VIDEO_MT9M114
 	tristate "onsemi MT9M114 sensor support"
 	select V4L2_CCI_I2C
+	select VIDEO_APTINA_PLL
 	help
 	  This is a Video4Linux2 sensor-level driver for the onsemi MT9M114
 	  camera.
diff --git a/drivers/media/i2c/mt9m114.c b/drivers/media/i2c/mt9m114.c
index 51ebbe7ae996950a58f8fee30029e0a060feaf3f..bbac5fd9b2ad85a1ab56a7e36de16659bc38a369 100644
--- a/drivers/media/i2c/mt9m114.c
+++ b/drivers/media/i2c/mt9m114.c
@@ -32,6 +32,8 @@
 #include <media/v4l2-mediabus.h>
 #include <media/v4l2-subdev.h>
 
+#include "aptina-pll.h"
+
 /* Sysctl registers */
 #define MT9M114_CHIP_ID					CCI_REG16(0x0000)
 #define MT9M114_COMMAND_REGISTER			CCI_REG16(0x0080)
@@ -267,9 +269,9 @@
 #define MT9M114_CAM_SYSCTL_PLL_ENABLE_VALUE			BIT(0)
 #define MT9M114_CAM_SYSCTL_PLL_DISABLE_VALUE			0x00
 #define MT9M114_CAM_SYSCTL_PLL_DIVIDER_M_N		CCI_REG16(0xc980)
-#define MT9M114_CAM_SYSCTL_PLL_DIVIDER_VALUE(m, n)		(((n) << 8) | (m))
+#define MT9M114_CAM_SYSCTL_PLL_DIVIDER_VALUE(m, n)		((((n) - 1) << 8) | (m))
 #define MT9M114_CAM_SYSCTL_PLL_DIVIDER_P		CCI_REG16(0xc982)
-#define MT9M114_CAM_SYSCTL_PLL_DIVIDER_P_VALUE(p)		((p) << 8)
+#define MT9M114_CAM_SYSCTL_PLL_DIVIDER_P_VALUE(p)		(((p) - 1) << 8)
 #define MT9M114_CAM_PORT_OUTPUT_CONTROL			CCI_REG16(0xc984)
 #define MT9M114_CAM_PORT_PORT_SELECT_PARALLEL			(0 << 0)
 #define MT9M114_CAM_PORT_PORT_SELECT_MIPI			(1 << 0)
@@ -330,7 +332,7 @@
  * minimum values that have been seen in register lists are 303 and 38, use
  * them.
  *
- * Set the default to achieve 1280x960 at 30fps.
+ * Set the default to achieve 1280x960 at 30fps with a 48 MHz pixclock.
  */
 #define MT9M114_MIN_HBLANK				303
 #define MT9M114_MIN_VBLANK				38
@@ -340,6 +342,8 @@
 #define MT9M114_DEF_FRAME_RATE				30
 #define MT9M114_MAX_FRAME_RATE				120
 
+#define MT9M114_DEF_PIXCLOCK				48000000
+
 #define MT9M114_PIXEL_ARRAY_WIDTH			1296U
 #define MT9M114_PIXEL_ARRAY_HEIGHT			976U
 
@@ -384,11 +388,7 @@ struct mt9m114 {
 	struct v4l2_fwnode_endpoint bus_cfg;
 	bool bypass_pll;
 
-	struct {
-		unsigned int m;
-		unsigned int n;
-		unsigned int p;
-	} pll;
+	struct aptina_pll pll;
 
 	unsigned int pixrate;
 	bool streaming;
@@ -758,7 +758,7 @@ static int mt9m114_initialize(struct mt9m114 *sensor)
 							       sensor->pll.n),
 			  &ret);
 		cci_write(sensor->regmap, MT9M114_CAM_SYSCTL_PLL_DIVIDER_P,
-			  MT9M114_CAM_SYSCTL_PLL_DIVIDER_P_VALUE(sensor->pll.p),
+			  MT9M114_CAM_SYSCTL_PLL_DIVIDER_P_VALUE(sensor->pll.p1),
 			  &ret);
 	}
 
@@ -2281,14 +2281,39 @@ static int mt9m114_verify_link_frequency(struct mt9m114 *sensor,
 	return 0;
 }
 
+/*
+ * Based on the docs the PLL is believed to have the following setup:
+ *
+ *         +-----+     +-----+     +-----+     +-----+     +-----+
+ * Fin --> | / N | --> | x M | --> | x 2 | --> | / P | --> | / 2 | -->
+ *         +-----+     +-----+     +-----+     +-----+     +-----+
+ *                                         fBit       fWord       fSensor
+ * ext_clock    int_clock   out_clock                             pix_clock
+ *
+ * The MT9M114 docs give a max fBit rate of 768 Mhz which translates to
+ * an out_clock_max of 384 Mhz.
+ */
 static int mt9m114_clk_init(struct mt9m114 *sensor)
 {
+	static const struct aptina_pll_limits limits = {
+		.ext_clock_min = 6000000,
+		.ext_clock_max = 54000000,
+		/* int_clock_* limits are not documented taken from mt9p031.c */
+		.int_clock_min = 2000000,
+		.int_clock_max = 13500000,
+		/* out_clock_min is not documented, taken from mt9p031.c */
+		.out_clock_min = 180000000,
+		.out_clock_max = 384000000,
+		.pix_clock_max = 48000000,
+		.n_min = 1,
+		.n_max = 64,
+		.m_min = 16,
+		.m_max = 192,
+		.p1_min = 8,
+		.p1_max = 8,
+	};
 	unsigned int pixrate;
-
-	/* Hardcode the PLL multiplier and dividers to default settings. */
-	sensor->pll.m = 32;
-	sensor->pll.n = 1;
-	sensor->pll.p = 7;
+	int ret;
 
 	/*
 	 * Calculate the pixel rate and link frequency. The CSI-2 bus is clocked
@@ -2308,8 +2333,15 @@ static int mt9m114_clk_init(struct mt9m114 *sensor)
 	}
 
 	/* Check if the PLL configuration fits the configured link frequency. */
-	pixrate = clk_get_rate(sensor->clk) * sensor->pll.m
-		/ ((sensor->pll.n + 1) * (sensor->pll.p + 1));
+	sensor->pll.ext_clock = clk_get_rate(sensor->clk);
+	sensor->pll.pix_clock = MT9M114_DEF_PIXCLOCK;
+
+	ret = aptina_pll_calculate(&sensor->client->dev, &limits, &sensor->pll);
+	if (ret)
+		return ret;
+
+	pixrate = sensor->pll.ext_clock * sensor->pll.m
+		/ (sensor->pll.n * sensor->pll.p1);
 	if (mt9m114_verify_link_frequency(sensor, pixrate) == 0) {
 		sensor->pixrate = pixrate;
 		sensor->bypass_pll = false;

-- 
2.52.0