[PATCH v4 23/36] media: imx: Add MIPI CSI-2 Receiver subdev driver

[Steve Longerbeam <slongerbeam@gmail.com>]

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

Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
---
 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
+	 * from the dphy_clk rate and the desired max lane bandwidth.
+	 * See drivers/gpu/drm/rockchip/dw-mipi-dsi.c for more info
+	 * on how this value is derived.
+	 */
+	dw_mipi_csi2_phy_write(csi2, 0x44, 0x14);
+}
+
+/*
+ * Waits for ultra-low-power state on D-PHY clock lane. This is currently
+ * unused and may not be needed at all, but keep around just in case.
+ */
+static int __maybe_unused csi2_dphy_wait_ulp(struct csi2_dev *csi2)
+{
+	u32 reg;
+	int ret;
+
+	/* wait for ULP on clock lane */
+	ret = readl_poll_timeout(csi2->base + CSI2_PHY_STATE, reg,
+				 !(reg & PHY_RXULPSCLKNOT), 0, 500000);
+	if (ret) {
+		v4l2_err(&csi2->sd, "ULP timeout, phy_state = 0x%08x\n", reg);
+		return ret;
+	}
+
+	/* wait until no errors on bus */
+	ret = readl_poll_timeout(csi2->base + CSI2_ERR1, reg,
+				 reg == 0x0, 0, 500000);
+	if (ret) {
+		v4l2_err(&csi2->sd, "stable bus timeout, err1 = 0x%08x\n", reg);
+		return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * Waits for low-power LP-11 state (aka STOPSTATE) on data and clock
+ * lanes.
+ */
+static int csi2_dphy_wait_stopstate(struct csi2_dev *csi2)
+{
+	u32 mask, reg;
+	int ret;
+
+	mask = PHY_STOPSTATECLK |
+		((csi2->bus.num_data_lanes - 1) << PHY_STOPSTATEDATA_BIT);
+
+	ret = readl_poll_timeout(csi2->base + CSI2_PHY_STATE, reg,
+				 (reg & mask) == mask, 0, 500000);
+	if (ret) {
+		v4l2_err(&csi2->sd, "LP-11 timeout, phy_state = 0x%08x\n", reg);
+		return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * Wait for active clock on the clock lane.
+ *
+ * FIXME: Currently unused, but it should be! It should be called
+ * from csi2_s_stream() below, at stream ON, but the required sequence
+ * of MIPI CSI-2 startup does not allow for an opportunity for this to
+ * be called. The sequence as specified in the i.MX6 reference manual
+ * is as follows:
+ *
+ * 1. Deassert presetn signal (global reset).
+ *        It's not clear what this "global reset" signal is (maybe APB
+ *        global reset), but in any case this step corresponds to
+ *        csi2_s_power(ON) here.
+ *
+ * 2. Configure MIPI Camera Sensor to put all Tx lanes in PL-11 state.
+ *        This must be carried out by the MIPI sensor's s_power(ON) subdev
+ *        op.
+ *
+ * 3. D-PHY initialization.
+ * 4. CSI2 Controller programming (Set N_LANES, deassert PHY_SHUTDOWNZ,
+ *    deassert PHY_RSTZ, deassert CSI2_RESETN).
+ * 5. Read the PHY status register (PHY_STATE) to confirm that all data and
+ *    clock lanes of the D-PHY are in Stop State.
+ *        These steps (3,4,5) are carried out by csi2_s_stream(ON) here.
+ *
+ * 6. Configure the MIPI Camera Sensor to start transmitting a clock on the
+ *    D-PHY clock lane.
+ *        This must be carried out by the MIPI sensor's s_stream(ON) subdev
+ *        op.
+ * 
+ * 7. CSI2 Controller programming - Read the PHY status register (PHY_STATE)
+ *    to confirm that the D-PHY is receiving a clock on the D-PHY clock lane.
+ *        This is implemented by this unused function, and _should_ be called
+ *        by csi2_s_stream(ON) here, but csi2_s_stream(ON) has been taken up
+ *        by steps 3,4,5 above already.
+ *
+ * In summary, a temporary solution would require a hard-coded delay in the
+ * MIPI sensor's s_stream(ON) op, to allow time for a stable clock lane.
+ *
+ * A longer term solution might be to create a new subdev op, perhaps
+ * called prepare_stream, that can be implemented here, and would be
+ * assigned steps 3,4,5. Then csi2_s_stream(ON) would become available
+ * as step 7.
+ */
+static int __maybe_unused csi2_dphy_wait_clock_lane(struct csi2_dev *csi2)
+{
+	u32 reg;
+	int ret;
+
+	ret = readl_poll_timeout(csi2->base + CSI2_PHY_STATE, reg,
+				 (reg & PHY_RXCLKACTIVEHS), 0, 500000);
+	if (ret) {
+		v4l2_err(&csi2->sd, "clock lane timeout, phy_state = 0x%08x\n",
+			 reg);
+		return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * V4L2 subdev operations.
+ */
+
+/* Startup Sequence Step 1 */
+static int csi2_s_power(struct v4l2_subdev *sd, int on)
+{
+	struct csi2_dev *csi2 = sd_to_dev(sd);
+	int ret;
+
+	if (on && !csi2->on) {
+		dev_dbg(csi2->dev, "power ON\n");
+		ret = clk_prepare_enable(csi2->cfg_clk);
+		if (ret)
+			return ret;
+		ret = clk_prepare_enable(csi2->dphy_clk);
+		if (ret)
+			goto cfg_clk_off;
+	} else if (!on && csi2->on) {
+		dev_dbg(csi2->dev, "power OFF\n");
+		clk_disable_unprepare(csi2->dphy_clk);
+		clk_disable_unprepare(csi2->cfg_clk);
+	}
+
+	csi2->on = on;
+
+	return 0;
+
+cfg_clk_off:
+	clk_disable_unprepare(csi2->cfg_clk);
+	return ret;
+}
+
+/* Startup Sequence Steps 3, 4, 5 */
+static int csi2_s_stream(struct v4l2_subdev *sd, int enable)
+{
+	struct csi2_dev *csi2 = sd_to_dev(sd);
+	int i, ret = 0;
+
+	if (!csi2->src_linked)
+		return -EPIPE;
+	for (i = 0; i < CSI2_NUM_SRC_PADS; i++) {
+		if (csi2->sink_linked[i])
+			break;
+	}
+	if (i >= CSI2_NUM_SRC_PADS)
+		return -EPIPE;
+
+	if (enable && !csi2->stream_on) {
+		dev_dbg(csi2->dev, "stream ON\n");
+
+		ret = clk_prepare_enable(csi2->pix_clk);
+		if (ret)
+			return ret;
+
+		/* Step 3 */
+		csi2_dphy_init(csi2);
+		/* Step 4 */
+		csi2_set_lanes(csi2);
+		csi2_enable(csi2, true);
+
+		/* Step 5 */
+		ret = csi2_dphy_wait_stopstate(csi2);
+		if (ret) {
+			csi2_enable(csi2, false);
+			clk_disable_unprepare(csi2->pix_clk);
+			return ret;
+		}
+	} else if (!enable && csi2->stream_on) {
+		dev_dbg(csi2->dev, "stream OFF\n");
+		csi2_enable(csi2, false);
+		clk_disable_unprepare(csi2->pix_clk);
+	}
+
+	csi2->stream_on = enable;
+	return 0;
+}
+
+static int csi2_link_setup(struct media_entity *entity,
+			   const struct media_pad *local,
+			   const struct media_pad *remote, u32 flags)
+{
+	struct v4l2_subdev *sd = media_entity_to_v4l2_subdev(entity);
+	struct csi2_dev *csi2 = sd_to_dev(sd);
+	struct v4l2_subdev *remote_sd;
+
+	dev_dbg(csi2->dev, "link setup %s -> %s", remote->entity->name,
+		local->entity->name);
+
+	remote_sd = media_entity_to_v4l2_subdev(remote->entity);
+
+	if (local->flags & MEDIA_PAD_FL_SOURCE) {
+		if (flags & MEDIA_LNK_FL_ENABLED) {
+			if (csi2->sink_linked[local->index])
+				return -EBUSY;
+			csi2->sink_linked[local->index] = true;
+		} else {
+			csi2->sink_linked[local->index] = false;
+		}
+	} else {
+		if (flags & MEDIA_LNK_FL_ENABLED) {
+			if (csi2->src_linked)
+				return -EBUSY;
+			csi2->src_linked = true;
+		} else {
+			csi2->src_linked = false;
+		}
+	}
+
+	return 0;
+}
+
+static int csi2_get_fmt(struct v4l2_subdev *sd,
+			struct v4l2_subdev_pad_config *cfg,
+			struct v4l2_subdev_format *sdformat)
+{
+	struct csi2_dev *csi2 = sd_to_dev(sd);
+	struct v4l2_mbus_framefmt *fmt;
+
+	if (sdformat->which == V4L2_SUBDEV_FORMAT_TRY)
+		fmt = v4l2_subdev_get_try_format(&csi2->sd, cfg,
+						 sdformat->pad);
+	else
+		fmt = &csi2->format_mbus;
+
+	sdformat->format = *fmt;
+
+	return 0;
+}
+
+static int csi2_set_fmt(struct v4l2_subdev *sd,
+			struct v4l2_subdev_pad_config *cfg,
+			struct v4l2_subdev_format *sdformat)
+{
+	struct csi2_dev *csi2 = sd_to_dev(sd);
+
+	if (sdformat->pad >= CSI2_NUM_PADS)
+		return -EINVAL;
+
+	if (csi2->stream_on)
+		return -EBUSY;
+
+	/* Output pads mirror active input pad, no limits on input pads */
+	if (sdformat->pad != CSI2_SINK_PAD)
+		sdformat->format = csi2->format_mbus;
+
+	if (sdformat->which == V4L2_SUBDEV_FORMAT_TRY)
+		cfg->try_fmt = sdformat->format;
+	else
+		csi2->format_mbus = sdformat->format;
+
+	return 0;
+}
+
+/*
+ * retrieve our pads parsed from the OF graph by the media device
+ */
+static int csi2_registered(struct v4l2_subdev *sd)
+{
+	struct csi2_dev *csi2 = sd_to_dev(sd);
+	int i, ret;
+
+	for (i = 0; i < CSI2_NUM_PADS; i++) {
+		csi2->pad[i].flags = (i == CSI2_SINK_PAD) ?
+		MEDIA_PAD_FL_SINK : MEDIA_PAD_FL_SOURCE;
+	}
+
+	/* set a default mbus format  */
+	ret = imx_media_init_mbus_fmt(&csi2->format_mbus,
+				      640, 480, 0, V4L2_FIELD_NONE, NULL);
+	if (ret)
+		return ret;
+
+	return media_entity_pads_init(&sd->entity, CSI2_NUM_PADS, csi2->pad);
+}
+
+static struct media_entity_operations csi2_entity_ops = {
+	.link_setup = csi2_link_setup,
+	.link_validate = v4l2_subdev_link_validate,
+};
+
+static struct v4l2_subdev_core_ops csi2_core_ops = {
+	.s_power = csi2_s_power,
+};
+
+static struct v4l2_subdev_video_ops csi2_video_ops = {
+	.s_stream = csi2_s_stream,
+};
+
+static struct v4l2_subdev_pad_ops csi2_pad_ops = {
+	.get_fmt = csi2_get_fmt,
+	.set_fmt = csi2_set_fmt,
+};
+
+static struct v4l2_subdev_ops csi2_subdev_ops = {
+	.core = &csi2_core_ops,
+	.video = &csi2_video_ops,
+	.pad = &csi2_pad_ops,
+};
+
+static struct v4l2_subdev_internal_ops csi2_internal_ops = {
+	.registered = csi2_registered,
+};
+
+static int csi2_parse_endpoints(struct csi2_dev *csi2)
+{
+	struct device_node *node = csi2->dev->of_node;
+	struct device_node *epnode;
+	struct v4l2_of_endpoint ep;
+
+	epnode = of_graph_get_endpoint_by_regs(node, 0, -1);
+	if (!epnode) {
+		v4l2_err(&csi2->sd, "failed to get sink endpoint node\n");
+		return -EINVAL;
+	}
+
+	v4l2_of_parse_endpoint(epnode, &ep);
+	of_node_put(epnode);
+
+	if (ep.bus_type != V4L2_MBUS_CSI2) {
+		v4l2_err(&csi2->sd, "invalid bus type, must be MIPI CSI2\n");
+		return -EINVAL;
+	}
+
+	csi2->bus = ep.bus.mipi_csi2;
+
+	dev_dbg(csi2->dev, "data lanes: %d\n", csi2->bus.num_data_lanes);
+	dev_dbg(csi2->dev, "flags: 0x%08x\n", csi2->bus.flags);
+	return 0;
+}
+
+static int csi2_probe(struct platform_device *pdev)
+{
+	struct csi2_dev *csi2;
+	struct resource *res;
+	int ret;
+
+	csi2 = devm_kzalloc(&pdev->dev, sizeof(*csi2), GFP_KERNEL);
+	if (!csi2)
+		return -ENOMEM;
+
+	csi2->dev = &pdev->dev;
+
+	v4l2_subdev_init(&csi2->sd, &csi2_subdev_ops);
+	v4l2_set_subdevdata(&csi2->sd, &pdev->dev);
+	csi2->sd.internal_ops = &csi2_internal_ops;
+	csi2->sd.entity.ops = &csi2_entity_ops;
+	csi2->sd.dev = &pdev->dev;
+	csi2->sd.owner = THIS_MODULE;
+	csi2->sd.flags = V4L2_SUBDEV_FL_HAS_DEVNODE;
+	strcpy(csi2->sd.name, DEVICE_NAME);
+	csi2->sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
+	csi2->sd.grp_id = IMX_MEDIA_GRP_ID_CSI2;
+
+	ret = csi2_parse_endpoints(csi2);
+	if (ret)
+		return ret;
+
+	csi2->cfg_clk = devm_clk_get(&pdev->dev, "cfg");
+	if (IS_ERR(csi2->cfg_clk)) {
+		v4l2_err(&csi2->sd, "failed to get cfg clock\n");
+		ret = PTR_ERR(csi2->cfg_clk);
+		return ret;
+	}
+
+	csi2->dphy_clk = devm_clk_get(&pdev->dev, "dphy");
+	if (IS_ERR(csi2->dphy_clk)) {
+		v4l2_err(&csi2->sd, "failed to get dphy clock\n");
+		ret = PTR_ERR(csi2->dphy_clk);
+		return ret;
+	}
+
+	csi2->pix_clk = devm_clk_get(&pdev->dev, "pix");
+	if (IS_ERR(csi2->pix_clk)) {
+		v4l2_err(&csi2->sd, "failed to get pixel clock\n");
+		ret = PTR_ERR(csi2->pix_clk);
+		return ret;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		v4l2_err(&csi2->sd, "failed to get platform resources\n");
+		return -ENODEV;
+	}
+
+	csi2->base = devm_ioremap(&pdev->dev, res->start, PAGE_SIZE);
+	if (!csi2->base) {
+		v4l2_err(&csi2->sd, "failed to map CSI-2 registers\n");
+		return -ENOMEM;
+	}
+
+	platform_set_drvdata(pdev, &csi2->sd);
+
+	return v4l2_async_register_subdev(&csi2->sd);
+}
+
+static int csi2_remove(struct platform_device *pdev)
+{
+	struct v4l2_subdev *sd = platform_get_drvdata(pdev);
+
+	csi2_s_power(sd, 0);
+
+	v4l2_async_unregister_subdev(sd);
+	media_entity_cleanup(&sd->entity);
+
+	return 0;
+}
+
+static const struct of_device_id csi2_dt_ids[] = {
+	{ .compatible = "fsl,imx6-mipi-csi2", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, csi2_dt_ids);
+
+static struct platform_driver csi2_driver = {
+	.driver = {
+		.name = DEVICE_NAME,
+		.of_match_table = csi2_dt_ids,
+	},
+	.probe = csi2_probe,
+	.remove = csi2_remove,
+};
+
+module_platform_driver(csi2_driver);
+
+MODULE_DESCRIPTION("i.MX5/6 MIPI CSI-2 Receiver driver");
+MODULE_AUTHOR("Steve Longerbeam <steve_longerbeam@mentor.com>");
+MODULE_LICENSE("GPL");
-- 
2.7.4