// SPDX-License-Identifier: GPL-2.0-only
/*
 * Goodix Touchscreen firmware upload support
 *
 * Copyright (c) 2021 Hans de Goede <hdegoede@redhat.com>
 *
 * This is a rewrite of gt9xx_update.c from the Allwinner H3 BSP which is:
 * Copyright (c) 2010 - 2012 Goodix Technology.
 * Author: andrew@goodix.com
 */

#include <linux/device.h>
#include <linux/firmware.h>
#include <linux/i2c.h>
#include "goodix.h"

#define GOODIX_FW_HEADER_LENGTH         sizeof(struct goodix_fw_header)
#define GOODIX_FW_SECTION_LENGTH        0x2000
#define GOODIX_FW_DSP_LENGTH            0x1000
#define GOODIX_FW_UPLOAD_ADDRESS        0xc000

#define GOODIX_CFG_LOC_HAVE_KEY          7
#define GOODIX_CFG_LOC_DRVA_NUM         27
#define GOODIX_CFG_LOC_DRVB_NUM         28
#define GOODIX_CFG_LOC_SENS_NUM         29

struct goodix_fw_header {
        u8 hw_info[4];
        u8 pid[8];
        u8 vid[2];
} __packed;

static u16 goodix_firmware_checksum(const u8 *data, int size)
{
        u16 checksum = 0;
        int i;

        for (i = 0; i < size; i += 2)
                checksum += (data[i] << 8) + data[i + 1];

        return checksum;
}

static int goodix_firmware_verify(struct device *dev, const struct firmware *fw)
{
        const struct goodix_fw_header *fw_header;
        size_t expected_size;
        const u8 *data;
        u16 checksum;
        char buf[9];

        expected_size = GOODIX_FW_HEADER_LENGTH + 4 * GOODIX_FW_SECTION_LENGTH +
                        GOODIX_FW_DSP_LENGTH;
        if (fw->size != expected_size) {
                dev_err(dev, "Firmware has wrong size, expected %zu got %zu\n",
                        expected_size, fw->size);
                return -EINVAL;
        }

        data = fw->data + GOODIX_FW_HEADER_LENGTH;
        checksum = goodix_firmware_checksum(data, 4 * GOODIX_FW_SECTION_LENGTH);
        if (checksum) {
                dev_err(dev, "Main firmware checksum error\n");
                return -EINVAL;
        }

        data += 4 * GOODIX_FW_SECTION_LENGTH;
        checksum = goodix_firmware_checksum(data, GOODIX_FW_DSP_LENGTH);
        if (checksum) {
                dev_err(dev, "DSP firmware checksum error\n");
                return -EINVAL;
        }

        fw_header = (const struct goodix_fw_header *)fw->data;
        dev_info(dev, "Firmware hardware info %02x%02x%02x%02x\n",
                 fw_header->hw_info[0], fw_header->hw_info[1],
                 fw_header->hw_info[2], fw_header->hw_info[3]);
        /* pid is a 8 byte buffer containing a string, weird I know */
        memcpy(buf, fw_header->pid, 8);
        buf[8] = 0;
        dev_info(dev, "Firmware PID: %s VID: %02x%02x\n", buf,
                 fw_header->vid[0], fw_header->vid[1]);
        return 0;
}

static int goodix_enter_upload_mode(struct i2c_client *client)
{
        int tries, error;
        u8 val;

        tries = 200;
        do {
                error = goodix_i2c_write_u8(client,
                                            GOODIX_REG_MISCTL_SWRST, 0x0c);
                if (error)
                        return error;

                error = goodix_i2c_read(client,
                                        GOODIX_REG_MISCTL_SWRST, &val, 1);
                if (error)
                        return error;

                if (val == 0x0c)
                        break;
        } while (--tries);

        if (!tries) {
                dev_err(&client->dev, "Error could not hold ss51 & dsp\n");
                return -EIO;
        }

        /* DSP_CK and DSP_ALU_CK PowerOn */
        error = goodix_i2c_write_u8(client, GOODIX_REG_MISCTL_DSP_CTL, 0x00);
        if (error)
                return error;

        /* Disable watchdog */
        error = goodix_i2c_write_u8(client, GOODIX_REG_MISCTL_TMR0_EN, 0x00);
        if (error)
                return error;

        /* Clear cache enable */
        error = goodix_i2c_write_u8(client, GOODIX_REG_MISCTL_CACHE_EN, 0x00);
        if (error)
                return error;

        /* Set boot from SRAM */
        error = goodix_i2c_write_u8(client, GOODIX_REG_MISCTL_BOOTCTL, 0x02);
        if (error)
                return error;

        /* Software reboot */
        error = goodix_i2c_write_u8(client,
                                    GOODIX_REG_MISCTL_CPU_SWRST_PULSE, 0x01);
        if (error)
                return error;

        /* Clear control flag */
        error = goodix_i2c_write_u8(client, GOODIX_REG_MISCTL_BOOTCTL, 0x00);
        if (error)
                return error;

        /* Set scramble */
        error = goodix_i2c_write_u8(client, GOODIX_REG_MISCTL_BOOT_OPT, 0x00);
        if (error)
                return error;

        /* Enable accessing code */
        error = goodix_i2c_write_u8(client, GOODIX_REG_MISCTL_MEM_CD_EN, 0x01);
        if (error)
                return error;

        return 0;
}

static int goodix_start_firmware(struct i2c_client *client)
{
        int error;
        u8 val;

        /* Init software watchdog */
        error = goodix_i2c_write_u8(client, GOODIX_REG_SW_WDT, 0xaa);
        if (error)
                return error;

        /* Release SS51 & DSP */
        error = goodix_i2c_write_u8(client, GOODIX_REG_MISCTL_SWRST, 0x00);
        if (error)
                return error;

        error = goodix_i2c_read(client, GOODIX_REG_SW_WDT, &val, 1);
        if (error)
                return error;

        /* The value we've written to SW_WDT should have been cleared now */
        if (val == 0xaa) {
                dev_err(&client->dev, "Error SW_WDT reg not cleared on fw startup\n");
                return -EIO;
        }

        /* Re-init software watchdog */
        error = goodix_i2c_write_u8(client, GOODIX_REG_SW_WDT, 0xaa);
        if (error)
                return error;

        return 0;
}

static int goodix_firmware_upload(struct goodix_ts_data *ts)
{
        const struct firmware *fw;
        char fw_name[64];
        const u8 *data;
        int error;

        snprintf(fw_name, sizeof(fw_name), "goodix/%s", ts->firmware_name);

        error = request_firmware(&fw, fw_name, &ts->client->dev);
        if (error) {
                dev_err(&ts->client->dev, "Firmware request error %d\n", error);
                return error;
        }

        error = goodix_firmware_verify(&ts->client->dev, fw);
        if (error)
                goto release;

        error = goodix_reset_no_int_sync(ts);
        if (error)
                goto release;

        error = goodix_enter_upload_mode(ts->client);
        if (error)
                goto release;

        /* Select SRAM bank 0 and upload section 1 & 2 */
        error = goodix_i2c_write_u8(ts->client,
                                    GOODIX_REG_MISCTL_SRAM_BANK, 0x00);
        if (error)
                goto release;

        data = fw->data + GOODIX_FW_HEADER_LENGTH;
        error = goodix_i2c_write(ts->client, GOODIX_FW_UPLOAD_ADDRESS,
                                 data, 2 * GOODIX_FW_SECTION_LENGTH);
        if (error)
                goto release;

        /* Select SRAM bank 1 and upload section 3 & 4 */
        error = goodix_i2c_write_u8(ts->client,
                                    GOODIX_REG_MISCTL_SRAM_BANK, 0x01);
        if (error)
                goto release;

        data += 2 * GOODIX_FW_SECTION_LENGTH;
        error = goodix_i2c_write(ts->client, GOODIX_FW_UPLOAD_ADDRESS,
                                 data, 2 * GOODIX_FW_SECTION_LENGTH);
        if (error)
                goto release;

        /* Select SRAM bank 2 and upload the DSP firmware */
        error = goodix_i2c_write_u8(ts->client,
                                    GOODIX_REG_MISCTL_SRAM_BANK, 0x02);
        if (error)
                goto release;

        data += 2 * GOODIX_FW_SECTION_LENGTH;
        error = goodix_i2c_write(ts->client, GOODIX_FW_UPLOAD_ADDRESS,
                                 data, GOODIX_FW_DSP_LENGTH);
        if (error)
                goto release;

        error = goodix_start_firmware(ts->client);
        if (error)
                goto release;

        error = goodix_int_sync(ts);
release:
        release_firmware(fw);
        return error;
}

static int goodix_prepare_bak_ref(struct goodix_ts_data *ts)
{
        u8 have_key, driver_num, sensor_num;

        if (ts->bak_ref)
                return 0; /* Already done */

        have_key = (ts->config[GOODIX_CFG_LOC_HAVE_KEY] & 0x01);

        driver_num = (ts->config[GOODIX_CFG_LOC_DRVA_NUM] & 0x1f) +
                     (ts->config[GOODIX_CFG_LOC_DRVB_NUM] & 0x1f);
        if (have_key)
                driver_num--;

        sensor_num = (ts->config[GOODIX_CFG_LOC_SENS_NUM] & 0x0f) +
                     ((ts->config[GOODIX_CFG_LOC_SENS_NUM] >> 4) & 0x0f);

        dev_dbg(&ts->client->dev, "Drv %d Sen %d Key %d\n",
                driver_num, sensor_num, have_key);

        ts->bak_ref_len = (driver_num * (sensor_num - 2) + 2) * 2;

        ts->bak_ref = devm_kzalloc(&ts->client->dev,
                                   ts->bak_ref_len, GFP_KERNEL);
        if (!ts->bak_ref)
                return -ENOMEM;

        /*
         * The bak_ref array contains the backup of an array of (self/auto)
         * calibration related values which the Android version of the driver
         * stores on the filesystem so that it can be restored after reboot.
         * The mainline kernel never writes directly to the filesystem like
         * this, we always start will all the values which give a correction
         * factor in approx. the -20 - +20 range (in 2s complement) set to 0.
         *
         * Note the touchscreen works fine without restoring the reference
         * values after a reboot / power-cycle.
         *
         * The last 2 bytes are a 16 bits unsigned checksum which is expected
         * to make the addition al all 16 bit unsigned values in the array add
         * up to 1 (rather then the usual 0), so we must set the last byte to 1.
         */
        ts->bak_ref[ts->bak_ref_len - 1] = 1;

        return 0;
}

static int goodix_send_main_clock(struct goodix_ts_data *ts)
{
        u32 main_clk = 54; /* Default main clock */
        u8 checksum = 0;
        int i;

        device_property_read_u32(&ts->client->dev,
                                 "goodix,main-clk", &main_clk);

        for (i = 0; i < (GOODIX_MAIN_CLK_LEN - 1); i++) {
                ts->main_clk[i] = main_clk;
                checksum += main_clk;
        }

        /* The value of all bytes combines must be 0 */
        ts->main_clk[GOODIX_MAIN_CLK_LEN - 1] = 256 - checksum;

        return goodix_i2c_write(ts->client, GOODIX_REG_MAIN_CLK,
                                ts->main_clk, GOODIX_MAIN_CLK_LEN);
}

int goodix_firmware_check(struct goodix_ts_data *ts)
{
        device_property_read_string(&ts->client->dev,
                                    "firmware-name", &ts->firmware_name);
        if (!ts->firmware_name)
                return 0;

        if (ts->irq_pin_access_method == IRQ_PIN_ACCESS_NONE) {
                dev_err(&ts->client->dev, "Error no IRQ-pin access method, cannot upload fw.\n");
                return -EINVAL;
        }

        dev_info(&ts->client->dev, "Touchscreen controller needs fw-upload\n");
        ts->load_cfg_from_disk = true;

        return goodix_firmware_upload(ts);
}

bool goodix_handle_fw_request(struct goodix_ts_data *ts)
{
        int error;
        u8 val;

        error = goodix_i2c_read(ts->client, GOODIX_REG_REQUEST, &val, 1);
        if (error)
                return false;

        switch (val) {
        case GOODIX_RQST_RESPONDED:
                /*
                 * If we read back our own last ack the IRQ was not for
                 * a request.
                 */
                return false;
        case GOODIX_RQST_CONFIG:
                error = goodix_send_cfg(ts, ts->config, ts->chip->config_len);
                if (error)
                        return false;

                break;
        case GOODIX_RQST_BAK_REF:
                error = goodix_prepare_bak_ref(ts);
                if (error)
                        return false;

                error = goodix_i2c_write(ts->client, GOODIX_REG_BAK_REF,
                                         ts->bak_ref, ts->bak_ref_len);
                if (error)
                        return false;

                break;
        case GOODIX_RQST_RESET:
                error = goodix_firmware_upload(ts);
                if (error)
                        return false;

                break;
        case GOODIX_RQST_MAIN_CLOCK:
                error = goodix_send_main_clock(ts);
                if (error)
                        return false;

                break;
        case GOODIX_RQST_UNKNOWN:
        case GOODIX_RQST_IDLE:
                break;
        default:
                dev_err_ratelimited(&ts->client->dev, "Unknown Request: 0x%02x\n", val);
        }

        /* Ack the request */
        goodix_i2c_write_u8(ts->client,
                            GOODIX_REG_REQUEST, GOODIX_RQST_RESPONDED);
        return true;
}

void goodix_save_bak_ref(struct goodix_ts_data *ts)
{
        int error;
        u8 val;

        if (!ts->firmware_name)
                return;

        error = goodix_i2c_read(ts->client, GOODIX_REG_STATUS, &val, 1);
        if (error)
                return;

        if (!(val & 0x80))
                return;

        error = goodix_i2c_read(ts->client, GOODIX_REG_BAK_REF,
                                ts->bak_ref, ts->bak_ref_len);
        if (error) {
                memset(ts->bak_ref, 0, ts->bak_ref_len);
                ts->bak_ref[ts->bak_ref_len - 1] = 1;
        }
}