/*
 * 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/of_graph.h>
#include <linux/platform_device.h>
#include <media/v4l2-device.h>
#include <media/v4l2-fwnode.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

/*
 * The default maximum bit-rate per lane in Mbps, if the
 * source subdev does not provide V4L2_CID_LINK_FREQ.
 */
#define CSI2_DEFAULT_MAX_MBPS 849

struct csi2_dev {
        struct device          *dev;
        struct v4l2_subdev      sd;
        struct media_pad       pad[CSI2_NUM_PADS];
        struct clk             *dphy_clk;
        struct clk             *pllref_clk;
        struct clk             *pix_clk; /* what is this? */
        void __iomem           *base;
        struct v4l2_fwnode_bus_mipi_csi2 bus;

        /* lock to protect all members below */
        struct mutex lock;

        struct v4l2_mbus_framefmt format_mbus;

        int                     stream_count;
        struct v4l2_subdev      *src_sd;
        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)
/*
 * i.MX CSI2IPU Gasket registers follow. The CSI2IPU gasket is
 * not part of the MIPI CSI-2 core, but its registers fall in the
 * same register map range.
 */
#define CSI2IPU_GASKET          0xf00
#define CSI2IPU_YUV422_YUYV     BIT(2)

static inline struct csi2_dev *sd_to_dev(struct v4l2_subdev *sdev)
{
        return container_of(sdev, struct csi2_dev, sd);
}

/*
 * The required sequence of MIPI CSI-2 startup 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 would be probably
 *        be carried out during driver load in csi2_probe().
 *
 * 2. Configure MIPI Camera Sensor to put all Tx lanes in LP-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 LP-11 state.
 * 6. Configure the MIPI Camera Sensor to start transmitting a clock on the
 *    D-PHY clock lane.
 * 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.
 *
 * All steps 3 through 7 are carried out by csi2_s_stream(ON) here. Step
 * 6 is accomplished by calling the source subdev's s_stream(ON) between
 * steps 5 and 7.
 */

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);
}

/*
 * This table is based on the table documented at
 * https://community.nxp.com/docs/DOC-94312. It assumes
 * a 27MHz D-PHY pll reference clock.
 */
static const struct {
        u32 max_mbps;
        u32 hsfreqrange_sel;
} hsfreq_map[] = {
        { 90, 0x00}, {100, 0x20}, {110, 0x40}, {125, 0x02},
        {140, 0x22}, {150, 0x42}, {160, 0x04}, {180, 0x24},
        {200, 0x44}, {210, 0x06}, {240, 0x26}, {250, 0x46},
        {270, 0x08}, {300, 0x28}, {330, 0x48}, {360, 0x2a},
        {400, 0x4a}, {450, 0x0c}, {500, 0x2c}, {550, 0x0e},
        {600, 0x2e}, {650, 0x10}, {700, 0x30}, {750, 0x12},
        {800, 0x32}, {850, 0x14}, {900, 0x34}, {950, 0x54},
        {1000, 0x74},
};

static int max_mbps_to_hsfreqrange_sel(u32 max_mbps)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(hsfreq_map); i++)
                if (hsfreq_map[i].max_mbps > max_mbps)
                        return hsfreq_map[i].hsfreqrange_sel;

        return -EINVAL;
}

static int csi2_dphy_init(struct csi2_dev *csi2)
{
        struct v4l2_ctrl *ctrl;
        u32 mbps_per_lane;
        int sel;

        ctrl = v4l2_ctrl_find(csi2->src_sd->ctrl_handler,
                              V4L2_CID_LINK_FREQ);
        if (!ctrl)
                mbps_per_lane = CSI2_DEFAULT_MAX_MBPS;
        else
                mbps_per_lane = DIV_ROUND_UP_ULL(2 * ctrl->qmenu_int[ctrl->val],
                                                 USEC_PER_SEC);

        sel = max_mbps_to_hsfreqrange_sel(mbps_per_lane);
        if (sel < 0)
                return sel;

        dw_mipi_csi2_phy_write(csi2, 0x44, sel);

        return 0;
}

/*
 * 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 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. */
static int 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;
}

/* Setup the i.MX CSI2IPU Gasket */
static void csi2ipu_gasket_init(struct csi2_dev *csi2)
{
        u32 reg = 0;

        switch (csi2->format_mbus.code) {
        case MEDIA_BUS_FMT_YUYV8_2X8:
        case MEDIA_BUS_FMT_YUYV8_1X16:
                reg = CSI2IPU_YUV422_YUYV;
                break;
        default:
                break;
        }

        writel(reg, csi2->base + CSI2IPU_GASKET);
}

static int csi2_start(struct csi2_dev *csi2)
{
        int ret;

        ret = clk_prepare_enable(csi2->pix_clk);
        if (ret)
                return ret;

        /* setup the gasket */
        csi2ipu_gasket_init(csi2);

        /* Step 3 */
        ret = csi2_dphy_init(csi2);
        if (ret)
                goto err_disable_clk;

        /* Step 4 */
        csi2_set_lanes(csi2);
        csi2_enable(csi2, true);

        /* Step 5 */
        ret = csi2_dphy_wait_stopstate(csi2);
        if (ret)
                goto err_assert_reset;

        /* Step 6 */
        ret = v4l2_subdev_call(csi2->src_sd, video, s_stream, 1);
        ret = (ret && ret != -ENOIOCTLCMD) ? ret : 0;
        if (ret)
                goto err_assert_reset;

        /* Step 7 */
        ret = csi2_dphy_wait_clock_lane(csi2);
        if (ret)
                goto err_stop_upstream;

        return 0;

err_stop_upstream:
        v4l2_subdev_call(csi2->src_sd, video, s_stream, 0);
err_assert_reset:
        csi2_enable(csi2, false);
err_disable_clk:
        clk_disable_unprepare(csi2->pix_clk);
        return ret;
}

static void csi2_stop(struct csi2_dev *csi2)
{
        /* stop upstream */
        v4l2_subdev_call(csi2->src_sd, video, s_stream, 0);

        csi2_enable(csi2, false);
        clk_disable_unprepare(csi2->pix_clk);
}

/*
 * V4L2 subdev operations.
 */

static int csi2_s_stream(struct v4l2_subdev *sd, int enable)
{
        struct csi2_dev *csi2 = sd_to_dev(sd);
        int i, ret = 0;

        mutex_lock(&csi2->lock);

        if (!csi2->src_sd) {
                ret = -EPIPE;
                goto out;
        }

        for (i = 0; i < CSI2_NUM_SRC_PADS; i++) {
                if (csi2->sink_linked[i])
                        break;
        }
        if (i >= CSI2_NUM_SRC_PADS) {
                ret = -EPIPE;
                goto out;
        }

        /*
         * enable/disable streaming only if stream_count is
         * going from 0 to 1 / 1 to 0.
         */
        if (csi2->stream_count != !enable)
                goto update_count;

        dev_dbg(csi2->dev, "stream %s\n", enable ? "ON" : "OFF");
        if (enable)
                ret = csi2_start(csi2);
        else
                csi2_stop(csi2);
        if (ret)
                goto out;

update_count:
        csi2->stream_count += enable ? 1 : -1;
        if (csi2->stream_count < 0)
                csi2->stream_count = 0;
out:
        mutex_unlock(&csi2->lock);
        return ret;
}

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;
        int ret = 0;

        dev_dbg(csi2->dev, "link setup %s -> %s", remote->entity->name,
                local->entity->name);

        remote_sd = media_entity_to_v4l2_subdev(remote->entity);

        mutex_lock(&csi2->lock);

        if (local->flags & MEDIA_PAD_FL_SOURCE) {
                if (flags & MEDIA_LNK_FL_ENABLED) {
                        if (csi2->sink_linked[local->index - 1]) {
                                ret = -EBUSY;
                                goto out;
                        }
                        csi2->sink_linked[local->index - 1] = true;
                } else {
                        csi2->sink_linked[local->index - 1] = false;
                }
        } else {
                if (flags & MEDIA_LNK_FL_ENABLED) {
                        if (csi2->src_sd) {
                                ret = -EBUSY;
                                goto out;
                        }
                        csi2->src_sd = remote_sd;
                } else {
                        csi2->src_sd = NULL;
                }
        }

out:
        mutex_unlock(&csi2->lock);
        return ret;
}

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;

        mutex_lock(&csi2->lock);

        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;

        mutex_unlock(&csi2->lock);

        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);
        int ret = 0;

        if (sdformat->pad >= CSI2_NUM_PADS)
                return -EINVAL;

        mutex_lock(&csi2->lock);

        if (csi2->stream_count > 0) {
                ret = -EBUSY;
                goto out;
        }

        /* 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;
out:
        mutex_unlock(&csi2->lock);
        return ret;
}

/*
 * 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 const struct media_entity_operations csi2_entity_ops = {
        .link_setup = csi2_link_setup,
        .link_validate = v4l2_subdev_link_validate,
};

static const struct v4l2_subdev_video_ops csi2_video_ops = {
        .s_stream = csi2_s_stream,
};

static const struct v4l2_subdev_pad_ops csi2_pad_ops = {
        .get_fmt = csi2_get_fmt,
        .set_fmt = csi2_set_fmt,
};

static const struct v4l2_subdev_ops csi2_subdev_ops = {
        .video = &csi2_video_ops,
        .pad = &csi2_pad_ops,
};

static const 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_fwnode_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_fwnode_endpoint_parse(of_fwnode_handle(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->pllref_clk = devm_clk_get(&pdev->dev, "ref");
        if (IS_ERR(csi2->pllref_clk)) {
                v4l2_err(&csi2->sd, "failed to get pll reference clock\n");
                ret = PTR_ERR(csi2->pllref_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;
        }

        mutex_init(&csi2->lock);

        ret = clk_prepare_enable(csi2->pllref_clk);
        if (ret) {
                v4l2_err(&csi2->sd, "failed to enable pllref_clk\n");
                goto rmmutex;
        }

        ret = clk_prepare_enable(csi2->dphy_clk);
        if (ret) {
                v4l2_err(&csi2->sd, "failed to enable dphy_clk\n");
                goto pllref_off;
        }

        platform_set_drvdata(pdev, &csi2->sd);

        ret = v4l2_async_register_subdev(&csi2->sd);
        if (ret)
                goto dphy_off;

        return 0;

dphy_off:
        clk_disable_unprepare(csi2->dphy_clk);
pllref_off:
        clk_disable_unprepare(csi2->pllref_clk);
rmmutex:
        mutex_destroy(&csi2->lock);
        return ret;
}

static int csi2_remove(struct platform_device *pdev)
{
        struct v4l2_subdev *sd = platform_get_drvdata(pdev);
        struct csi2_dev *csi2 = sd_to_dev(sd);

        v4l2_async_unregister_subdev(sd);
        clk_disable_unprepare(csi2->dphy_clk);
        clk_disable_unprepare(csi2->pllref_clk);
        mutex_destroy(&csi2->lock);
        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");