// SPDX-License-Identifier: GPL-2.0
/*
 * Raspberry Pi firmware based touchscreen driver
 *
 * Copyright (C) 2015, 2017 Raspberry Pi
 * Copyright (C) 2018 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
 */

#include <linux/io.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/bitops.h>
#include <linux/dma-mapping.h>
#include <linux/platform_device.h>
#include <linux/input.h>
#include <linux/input/mt.h>
#include <linux/input/touchscreen.h>
#include <soc/bcm2835/raspberrypi-firmware.h>

#define RPI_TS_DEFAULT_WIDTH    800
#define RPI_TS_DEFAULT_HEIGHT   480

#define RPI_TS_MAX_SUPPORTED_POINTS     10

#define RPI_TS_FTS_TOUCH_DOWN           0
#define RPI_TS_FTS_TOUCH_CONTACT        2

#define RPI_TS_POLL_INTERVAL            17      /* 60fps */

#define RPI_TS_NPOINTS_REG_INVALIDATE   99

struct rpi_ts {
        struct platform_device *pdev;
        struct input_dev *input;
        struct touchscreen_properties prop;

        void __iomem *fw_regs_va;
        dma_addr_t fw_regs_phys;

        int known_ids;
};

struct rpi_ts_regs {
        u8 device_mode;
        u8 gesture_id;
        u8 num_points;
        struct rpi_ts_touch {
                u8 xh;
                u8 xl;
                u8 yh;
                u8 yl;
                u8 pressure; /* Not supported */
                u8 area;     /* Not supported */
        } point[RPI_TS_MAX_SUPPORTED_POINTS];
};

static void rpi_ts_poll(struct input_dev *input)
{
        struct rpi_ts *ts = input_get_drvdata(input);
        struct rpi_ts_regs regs;
        int modified_ids = 0;
        long released_ids;
        int event_type;
        int touchid;
        int x, y;
        int i;

        memcpy_fromio(&regs, ts->fw_regs_va, sizeof(regs));
        /*
         * We poll the memory based register copy of the touchscreen chip using
         * the number of points register to know whether the copy has been
         * updated (we write 99 to the memory copy, the GPU will write between
         * 0 - 10 points)
         */
        iowrite8(RPI_TS_NPOINTS_REG_INVALIDATE,
                 ts->fw_regs_va + offsetof(struct rpi_ts_regs, num_points));

        if (regs.num_points == RPI_TS_NPOINTS_REG_INVALIDATE ||
            (regs.num_points == 0 && ts->known_ids == 0))
                return;

        for (i = 0; i < regs.num_points; i++) {
                x = (((int)regs.point[i].xh & 0xf) << 8) + regs.point[i].xl;
                y = (((int)regs.point[i].yh & 0xf) << 8) + regs.point[i].yl;
                touchid = (regs.point[i].yh >> 4) & 0xf;
                event_type = (regs.point[i].xh >> 6) & 0x03;

                modified_ids |= BIT(touchid);

                if (event_type == RPI_TS_FTS_TOUCH_DOWN ||
                    event_type == RPI_TS_FTS_TOUCH_CONTACT) {
                        input_mt_slot(input, touchid);
                        input_mt_report_slot_state(input, MT_TOOL_FINGER, 1);
                        touchscreen_report_pos(input, &ts->prop, x, y, true);
                }
        }

        released_ids = ts->known_ids & ~modified_ids;
        for_each_set_bit(i, &released_ids, RPI_TS_MAX_SUPPORTED_POINTS) {
                input_mt_slot(input, i);
                input_mt_report_slot_inactive(input);
                modified_ids &= ~(BIT(i));
        }
        ts->known_ids = modified_ids;

        input_mt_sync_frame(input);
        input_sync(input);
}

static void rpi_ts_dma_cleanup(void *data)
{
        struct rpi_ts *ts = data;
        struct device *dev = &ts->pdev->dev;

        dma_free_coherent(dev, PAGE_SIZE, ts->fw_regs_va, ts->fw_regs_phys);
}

static int rpi_ts_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct device_node *np = dev->of_node;
        struct input_dev *input;
        struct rpi_firmware *fw;
        struct rpi_ts *ts;
        u32 touchbuf;
        int error;

        struct device_node *fw_node __free(device_node) = of_get_parent(np);
        if (!fw_node) {
                dev_err(dev, "Missing firmware node\n");
                return -ENOENT;
        }

        fw = devm_rpi_firmware_get(&pdev->dev, fw_node);
        if (!fw)
                return -EPROBE_DEFER;

        ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
        if (!ts)
                return -ENOMEM;
        ts->pdev = pdev;

        ts->fw_regs_va = dma_alloc_coherent(dev, PAGE_SIZE, &ts->fw_regs_phys,
                                            GFP_KERNEL);
        if (!ts->fw_regs_va) {
                dev_err(dev, "failed to dma_alloc_coherent\n");
                return -ENOMEM;
        }

        error = devm_add_action_or_reset(dev, rpi_ts_dma_cleanup, ts);
        if (error) {
                dev_err(dev, "failed to devm_add_action_or_reset, %d\n", error);
                return error;
        }

        touchbuf = (u32)ts->fw_regs_phys;
        error = rpi_firmware_property(fw, RPI_FIRMWARE_FRAMEBUFFER_SET_TOUCHBUF,
                                      &touchbuf, sizeof(touchbuf));
        if (error || touchbuf != 0) {
                dev_warn(dev, "Failed to set touchbuf, %d\n", error);
                return error;
        }

        input = devm_input_allocate_device(dev);
        if (!input) {
                dev_err(dev, "Failed to allocate input device\n");
                return -ENOMEM;
        }

        ts->input = input;
        input_set_drvdata(input, ts);

        input->name = "raspberrypi-ts";
        input->id.bustype = BUS_HOST;

        input_set_abs_params(input, ABS_MT_POSITION_X, 0,
                             RPI_TS_DEFAULT_WIDTH, 0, 0);
        input_set_abs_params(input, ABS_MT_POSITION_Y, 0,
                             RPI_TS_DEFAULT_HEIGHT, 0, 0);
        touchscreen_parse_properties(input, true, &ts->prop);

        error = input_mt_init_slots(input, RPI_TS_MAX_SUPPORTED_POINTS,
                                    INPUT_MT_DIRECT);
        if (error) {
                dev_err(dev, "could not init mt slots, %d\n", error);
                return error;
        }

        error = input_setup_polling(input, rpi_ts_poll);
        if (error) {
                dev_err(dev, "could not set up polling mode, %d\n", error);
                return error;
        }

        input_set_poll_interval(input, RPI_TS_POLL_INTERVAL);

        error = input_register_device(input);
        if (error) {
                dev_err(dev, "could not register input device, %d\n", error);
                return error;
        }

        return 0;
}

static const struct of_device_id rpi_ts_match[] = {
        { .compatible = "raspberrypi,firmware-ts", },
        {},
};
MODULE_DEVICE_TABLE(of, rpi_ts_match);

static struct platform_driver rpi_ts_driver = {
        .driver = {
                .name = "raspberrypi-ts",
                .of_match_table = rpi_ts_match,
        },
        .probe = rpi_ts_probe,
};
module_platform_driver(rpi_ts_driver);

MODULE_AUTHOR("Gordon Hollingworth");
MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
MODULE_DESCRIPTION("Raspberry Pi firmware based touchscreen driver");
MODULE_LICENSE("GPL v2");