On Fri, 2017-02-17 at 11:47 +0100, Philipp Zabel wrote:

On Wed, 2017-02-15 at 18:19 -0800, Steve Longerbeam wrote:

quoted

Adds MIPI CSI-2 Receiver subdev driver. This subdev is required
for sensors with a MIPI CSI2 interface.

Signed-off-by: Steve Longerbeam <redacted>
---
 drivers/staging/media/imx/Makefile         |   1 +
 drivers/staging/media/imx/imx6-mipi-csi2.c | 573 +++++++++++++++++++++++++++++
 2 files changed, 574 insertions(+)
 create mode 100644 drivers/staging/media/imx/imx6-mipi-csi2.c

diff --git a/drivers/staging/media/imx/Makefile b/drivers/staging/media/imx/Makefile
index 878a126..3569625 100644
--- a/drivers/staging/media/imx/Makefile
+++ b/drivers/staging/media/imx/Makefile

@@ -9,3 +9,4 @@ obj-$(CONFIG_VIDEO_IMX_MEDIA) += imx-media-vdic.o
 obj-$(CONFIG_VIDEO_IMX_MEDIA) += imx-media-ic.o
 
 obj-$(CONFIG_VIDEO_IMX_CSI) += imx-media-csi.o
+obj-$(CONFIG_VIDEO_IMX_CSI) += imx6-mipi-csi2.o

diff --git a/drivers/staging/media/imx/imx6-mipi-csi2.c b/drivers/staging/media/imx/imx6-mipi-csi2.c
new file mode 100644
index 0000000..23dca80
--- /dev/null
+++ b/drivers/staging/media/imx/imx6-mipi-csi2.c

@@ -0,0 +1,573 @@
+/*
+ * MIPI CSI-2 Receiver Subdev for Freescale i.MX6 SOC.
+ *
+ * Copyright (c) 2012-2017 Mentor Graphics Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <media/v4l2-device.h>
+#include <media/v4l2-of.h>
+#include <media/v4l2-subdev.h>
+#include "imx-media.h"
+
+/*
+ * there must be 5 pads: 1 input pad from sensor, and
+ * the 4 virtual channel output pads
+ */
+#define CSI2_SINK_PAD       0
+#define CSI2_NUM_SINK_PADS  1
+#define CSI2_NUM_SRC_PADS   4
+#define CSI2_NUM_PADS       5
+
+struct csi2_dev {
+	struct device          *dev;
+	struct v4l2_subdev      sd;
+	struct media_pad       pad[CSI2_NUM_PADS];
+	struct v4l2_mbus_framefmt format_mbus;
+	struct clk             *dphy_clk;
+	struct clk             *cfg_clk;
+	struct clk             *pix_clk; /* what is this? */
+	void __iomem           *base;
+	struct v4l2_of_bus_mipi_csi2 bus;
+	bool                    on;
+	bool                    stream_on;
+	bool                    src_linked;
+	bool                    sink_linked[CSI2_NUM_SRC_PADS];
+};
+
+#define DEVICE_NAME "imx6-mipi-csi2"
+
+/* Register offsets */
+#define CSI2_VERSION            0x000
+#define CSI2_N_LANES            0x004
+#define CSI2_PHY_SHUTDOWNZ      0x008
+#define CSI2_DPHY_RSTZ          0x00c
+#define CSI2_RESETN             0x010
+#define CSI2_PHY_STATE          0x014
+#define PHY_STOPSTATEDATA_BIT   4
+#define PHY_STOPSTATEDATA(n)    BIT(PHY_STOPSTATEDATA_BIT + (n))
+#define PHY_RXCLKACTIVEHS       BIT(8)
+#define PHY_RXULPSCLKNOT        BIT(9)
+#define PHY_STOPSTATECLK        BIT(10)
+#define CSI2_DATA_IDS_1         0x018
+#define CSI2_DATA_IDS_2         0x01c
+#define CSI2_ERR1               0x020
+#define CSI2_ERR2               0x024
+#define CSI2_MSK1               0x028
+#define CSI2_MSK2               0x02c
+#define CSI2_PHY_TST_CTRL0      0x030
+#define PHY_TESTCLR		BIT(0)
+#define PHY_TESTCLK		BIT(1)
+#define CSI2_PHY_TST_CTRL1      0x034
+#define PHY_TESTEN		BIT(16)
+#define CSI2_SFT_RESET          0xf00
+
+static inline struct csi2_dev *sd_to_dev(struct v4l2_subdev *sdev)
+{
+	return container_of(sdev, struct csi2_dev, sd);
+}
+
+static void csi2_enable(struct csi2_dev *csi2, bool enable)
+{
+	if (enable) {
+		writel(0x1, csi2->base + CSI2_PHY_SHUTDOWNZ);
+		writel(0x1, csi2->base + CSI2_DPHY_RSTZ);
+		writel(0x1, csi2->base + CSI2_RESETN);
+	} else {
+		writel(0x0, csi2->base + CSI2_PHY_SHUTDOWNZ);
+		writel(0x0, csi2->base + CSI2_DPHY_RSTZ);
+		writel(0x0, csi2->base + CSI2_RESETN);
+	}
+}
+
+static void csi2_set_lanes(struct csi2_dev *csi2)
+{
+	int lanes = csi2->bus.num_data_lanes;
+
+	writel(lanes - 1, csi2->base + CSI2_N_LANES);
+}
+
+static void dw_mipi_csi2_phy_write(struct csi2_dev *csi2,
+				   u32 test_code, u32 test_data)
+{
+	/* Clear PHY test interface */
+	writel(PHY_TESTCLR, csi2->base + CSI2_PHY_TST_CTRL0);
+	writel(0x0, csi2->base + CSI2_PHY_TST_CTRL1);
+	writel(0x0, csi2->base + CSI2_PHY_TST_CTRL0);
+
+	/* Raise test interface strobe signal */
+	writel(PHY_TESTCLK, csi2->base + CSI2_PHY_TST_CTRL0);
+
+	/* Configure address write on falling edge and lower strobe signal */
+	writel(PHY_TESTEN | test_code, csi2->base + CSI2_PHY_TST_CTRL1);
+	writel(0x0, csi2->base + CSI2_PHY_TST_CTRL0);
+
+	/* Configure data write on rising edge and raise strobe signal */
+	writel(test_data, csi2->base + CSI2_PHY_TST_CTRL1);
+	writel(PHY_TESTCLK, csi2->base + CSI2_PHY_TST_CTRL0);
+
+	/* Clear strobe signal */
+	writel(0x0, csi2->base + CSI2_PHY_TST_CTRL0);
+}
+
+static void csi2_dphy_init(struct csi2_dev *csi2)
+{
+	/*
+	 * FIXME: 0x14 is derived from a fixed D-PHY reference
+	 * clock from the HSI_TX PLL, and a fixed target lane max
+	 * bandwidth of 300 Mbps. This value should be derived

If the table in https://community.nxp.com/docs/DOC-94312 is correct,
this should be 850 Mbps. Where does this 300 Mbps value come from?

I got it, the dptdin_map value for 300 Mbps is 0x14 in the Rockchip DSI
driver. But that value is written to the register as HSFREQRANGE_SEL(x):

#define HSFREQRANGE_SEL(val)    (((val) & 0x3f) << 1) 

which is 0x28. Further, the Rockchip D-PHY probably is another version,
as its max_mbps goes up to 1500.

regards
Philipp