// SPDX-License-Identifier: GPL-2.0-only
/*
 * Compaq iPAQ h3xxx Atmel microcontroller companion support
 *
 * This is an Atmel AT90LS8535 with a special flashed-in firmware that
 * implements the special protocol used by this driver.
 *
 * based on previous kernel 2.4 version by Andrew Christian
 * Author : Alessandro Gardich <gremlin@gremlin.it>
 * Author : Dmitry Artamonow <mad_soft@inbox.ru>
 * Author : Linus Walleij <linus.walleij@linaro.org>
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/pm.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/mfd/core.h>
#include <linux/mfd/ipaq-micro.h>
#include <linux/string.h>
#include <linux/string_choices.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/list.h>

#include <mach/hardware.h>

static void ipaq_micro_trigger_tx(struct ipaq_micro *micro)
{
        struct ipaq_micro_txdev *tx = &micro->tx;
        struct ipaq_micro_msg *msg = micro->msg;
        int i, bp;
        u8 checksum;
        u32 val;

        bp = 0;
        tx->buf[bp++] = CHAR_SOF;

        checksum = ((msg->id & 0x0f) << 4) | (msg->tx_len & 0x0f);
        tx->buf[bp++] = checksum;

        for (i = 0; i < msg->tx_len; i++) {
                tx->buf[bp++] = msg->tx_data[i];
                checksum += msg->tx_data[i];
        }

        tx->buf[bp++] = checksum;
        tx->len = bp;
        tx->index = 0;

        /* Enable interrupt */
        val = readl(micro->base + UTCR3);
        val |= UTCR3_TIE;
        writel(val, micro->base + UTCR3);
}

int ipaq_micro_tx_msg(struct ipaq_micro *micro, struct ipaq_micro_msg *msg)
{
        unsigned long flags;

        dev_dbg(micro->dev, "TX msg: %02x, %d bytes\n", msg->id, msg->tx_len);

        spin_lock_irqsave(&micro->lock, flags);
        if (micro->msg) {
                list_add_tail(&msg->node, &micro->queue);
                spin_unlock_irqrestore(&micro->lock, flags);
                return 0;
        }
        micro->msg = msg;
        ipaq_micro_trigger_tx(micro);
        spin_unlock_irqrestore(&micro->lock, flags);
        return 0;
}
EXPORT_SYMBOL(ipaq_micro_tx_msg);

static void micro_rx_msg(struct ipaq_micro *micro, u8 id, int len, u8 *data)
{
        dev_dbg(micro->dev, "RX msg: %02x, %d bytes\n", id, len);

        spin_lock(&micro->lock);
        switch (id) {
        case MSG_VERSION:
        case MSG_EEPROM_READ:
        case MSG_EEPROM_WRITE:
        case MSG_BACKLIGHT:
        case MSG_NOTIFY_LED:
        case MSG_THERMAL_SENSOR:
        case MSG_BATTERY:
                /* Handle synchronous messages */
                if (micro->msg && micro->msg->id == id) {
                        struct ipaq_micro_msg *msg = micro->msg;

                        memcpy(msg->rx_data, data, len);
                        msg->rx_len = len;
                        complete(&micro->msg->ack);
                        if (!list_empty(&micro->queue)) {
                                micro->msg = list_entry(micro->queue.next,
                                                        struct ipaq_micro_msg,
                                                        node);
                                list_del_init(&micro->msg->node);
                                ipaq_micro_trigger_tx(micro);
                        } else
                                micro->msg = NULL;
                        dev_dbg(micro->dev, "OK RX message 0x%02x\n", id);
                } else {
                        dev_err(micro->dev,
                                "out of band RX message 0x%02x\n", id);
                        if (!micro->msg)
                                dev_info(micro->dev, "no message queued\n");
                        else
                                dev_info(micro->dev, "expected message %02x\n",
                                         micro->msg->id);
                }
                break;
        case MSG_KEYBOARD:
                if (micro->key)
                        micro->key(micro->key_data, len, data);
                else
                        dev_dbg(micro->dev, "key message ignored, no handle\n");
                break;
        case MSG_TOUCHSCREEN:
                if (micro->ts)
                        micro->ts(micro->ts_data, len, data);
                else
                        dev_dbg(micro->dev, "touchscreen message ignored, no handle\n");
                break;
        default:
                dev_err(micro->dev,
                        "unknown msg %d [%d] %*ph\n", id, len, len, data);
                break;
        }
        spin_unlock(&micro->lock);
}

static void micro_process_char(struct ipaq_micro *micro, u8 ch)
{
        struct ipaq_micro_rxdev *rx = &micro->rx;

        switch (rx->state) {
        case STATE_SOF: /* Looking for SOF */
                if (ch == CHAR_SOF)
                        rx->state = STATE_ID; /* Next byte is the id and len */
                break;
        case STATE_ID: /* Looking for id and len byte */
                rx->id = (ch & 0xf0) >> 4;
                rx->len = (ch & 0x0f);
                rx->index = 0;
                rx->chksum = ch;
                rx->state = (rx->len > 0) ? STATE_DATA : STATE_CHKSUM;
                break;
        case STATE_DATA: /* Looking for 'len' data bytes */
                rx->chksum += ch;
                rx->buf[rx->index] = ch;
                if (++rx->index == rx->len)
                        rx->state = STATE_CHKSUM;
                break;
        case STATE_CHKSUM: /* Looking for the checksum */
                if (ch == rx->chksum)
                        micro_rx_msg(micro, rx->id, rx->len, rx->buf);
                rx->state = STATE_SOF;
                break;
        }
}

static void micro_rx_chars(struct ipaq_micro *micro)
{
        u32 status, ch;

        while ((status = readl(micro->base + UTSR1)) & UTSR1_RNE) {
                ch = readl(micro->base + UTDR);
                if (status & UTSR1_PRE)
                        dev_err(micro->dev, "rx: parity error\n");
                else if (status & UTSR1_FRE)
                        dev_err(micro->dev, "rx: framing error\n");
                else if (status & UTSR1_ROR)
                        dev_err(micro->dev, "rx: overrun error\n");
                micro_process_char(micro, ch);
        }
}

static void ipaq_micro_get_version(struct ipaq_micro *micro)
{
        struct ipaq_micro_msg msg = {
                .id = MSG_VERSION,
        };

        ipaq_micro_tx_msg_sync(micro, &msg);
        if (msg.rx_len == 4) {
                memcpy(micro->version, msg.rx_data, 4);
                micro->version[4] = '\0';
        } else if (msg.rx_len == 9) {
                memcpy(micro->version, msg.rx_data, 4);
                micro->version[4] = '\0';
                /* Bytes 4-7 are "pack", byte 8 is "boot type" */
        } else {
                dev_err(micro->dev,
                        "illegal version message %d bytes\n", msg.rx_len);
        }
}

static void ipaq_micro_eeprom_read(struct ipaq_micro *micro,
                                   u8 address, u8 len, u8 *data)
{
        struct ipaq_micro_msg msg = {
                .id = MSG_EEPROM_READ,
        };
        u8 i;

        for (i = 0; i < len; i++) {
                msg.tx_data[0] = address + i;
                msg.tx_data[1] = 1;
                msg.tx_len = 2;
                ipaq_micro_tx_msg_sync(micro, &msg);
                memcpy(data + (i * 2), msg.rx_data, 2);
        }
}

static char *ipaq_micro_str(u8 *wchar, u8 len)
{
        char retstr[256];
        u8 i;

        for (i = 0; i < len / 2; i++)
                retstr[i] = wchar[i * 2];
        return kstrdup(retstr, GFP_KERNEL);
}

static u16 ipaq_micro_to_u16(u8 *data)
{
        return data[1] << 8 | data[0];
}

static void __init ipaq_micro_eeprom_dump(struct ipaq_micro *micro)
{
        u8 dump[256];
        char *str;

        ipaq_micro_eeprom_read(micro, 0, 128, dump);
        str = ipaq_micro_str(dump, 10);
        if (str) {
                dev_info(micro->dev, "HW version %s\n", str);
                kfree(str);
        }
        str = ipaq_micro_str(dump+10, 40);
        if (str) {
                dev_info(micro->dev, "serial number: %s\n", str);
                /* Feed the random pool with this */
                add_device_randomness(str, strlen(str));
                kfree(str);
        }
        str = ipaq_micro_str(dump+50, 20);
        if (str) {
                dev_info(micro->dev, "module ID: %s\n", str);
                kfree(str);
        }
        str = ipaq_micro_str(dump+70, 10);
        if (str) {
                dev_info(micro->dev, "product revision: %s\n", str);
                kfree(str);
        }
        dev_info(micro->dev, "product ID: %u\n", ipaq_micro_to_u16(dump+80));
        dev_info(micro->dev, "frame rate: %u fps\n",
                 ipaq_micro_to_u16(dump+82));
        dev_info(micro->dev, "page mode: %u\n", ipaq_micro_to_u16(dump+84));
        dev_info(micro->dev, "country ID: %u\n", ipaq_micro_to_u16(dump+86));
        dev_info(micro->dev, "color display: %s\n",
                 str_yes_no(ipaq_micro_to_u16(dump + 88)));
        dev_info(micro->dev, "ROM size: %u MiB\n", ipaq_micro_to_u16(dump+90));
        dev_info(micro->dev, "RAM size: %u KiB\n", ipaq_micro_to_u16(dump+92));
        dev_info(micro->dev, "screen: %u x %u\n",
                 ipaq_micro_to_u16(dump+94), ipaq_micro_to_u16(dump+96));
}

static void micro_tx_chars(struct ipaq_micro *micro)
{
        struct ipaq_micro_txdev *tx = &micro->tx;
        u32 val;

        while ((tx->index < tx->len) &&
               (readl(micro->base + UTSR1) & UTSR1_TNF)) {
                writel(tx->buf[tx->index], micro->base + UTDR);
                tx->index++;
        }

        /* Stop interrupts */
        val = readl(micro->base + UTCR3);
        val &= ~UTCR3_TIE;
        writel(val, micro->base + UTCR3);
}

static void micro_reset_comm(struct ipaq_micro *micro)
{
        struct ipaq_micro_rxdev *rx = &micro->rx;
        u32 val;

        if (micro->msg)
                complete(&micro->msg->ack);

        /* Initialize Serial channel protocol frame */
        rx->state = STATE_SOF;  /* Reset the state machine */

        /* Set up interrupts */
        writel(0x01, micro->sdlc + 0x0); /* Select UART mode */

        /* Clean up CR3 */
        writel(0x0, micro->base + UTCR3);

        /* Format: 8N1 */
        writel(UTCR0_8BitData | UTCR0_1StpBit, micro->base + UTCR0);

        /* Baud rate: 115200 */
        writel(0x0, micro->base + UTCR1);
        writel(0x1, micro->base + UTCR2);

        /* Clear SR0 */
        writel(0xff, micro->base + UTSR0);

        /* Enable RX int, disable TX int */
        writel(UTCR3_TXE | UTCR3_RXE | UTCR3_RIE, micro->base + UTCR3);
        val = readl(micro->base + UTCR3);
        val &= ~UTCR3_TIE;
        writel(val, micro->base + UTCR3);
}

static irqreturn_t micro_serial_isr(int irq, void *dev_id)
{
        struct ipaq_micro *micro = dev_id;
        struct ipaq_micro_txdev *tx = &micro->tx;
        u32 status;

        status = readl(micro->base + UTSR0);
        do {
                if (status & (UTSR0_RID | UTSR0_RFS)) {
                        if (status & UTSR0_RID)
                                /* Clear the Receiver IDLE bit */
                                writel(UTSR0_RID, micro->base + UTSR0);
                        micro_rx_chars(micro);
                }

                /* Clear break bits */
                if (status & (UTSR0_RBB | UTSR0_REB))
                        writel(status & (UTSR0_RBB | UTSR0_REB),
                               micro->base + UTSR0);

                if (status & UTSR0_TFS)
                        micro_tx_chars(micro);

                status = readl(micro->base + UTSR0);

        } while (((tx->index < tx->len) && (status & UTSR0_TFS)) ||
                 (status & (UTSR0_RFS | UTSR0_RID)));

        return IRQ_HANDLED;
}

static const struct mfd_cell micro_cells[] = {
        { .name = "ipaq-micro-backlight", },
        { .name = "ipaq-micro-battery", },
        { .name = "ipaq-micro-keys", },
        { .name = "ipaq-micro-ts", },
        { .name = "ipaq-micro-leds", },
};

static int __maybe_unused micro_resume(struct device *dev)
{
        struct ipaq_micro *micro = dev_get_drvdata(dev);

        micro_reset_comm(micro);
        mdelay(10);

        return 0;
}

static int __init micro_probe(struct platform_device *pdev)
{
        struct ipaq_micro *micro;
        int ret;
        int irq;

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

        micro->dev = &pdev->dev;

        micro->base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
        if (IS_ERR(micro->base))
                return PTR_ERR(micro->base);

        micro->sdlc = devm_platform_ioremap_resource(pdev, 1);
        if (IS_ERR(micro->sdlc))
                return PTR_ERR(micro->sdlc);

        micro_reset_comm(micro);

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return -EINVAL;
        ret = devm_request_irq(&pdev->dev, irq, micro_serial_isr,
                               IRQF_SHARED, "ipaq-micro",
                               micro);
        if (ret) {
                dev_err(&pdev->dev, "unable to grab serial port IRQ\n");
                return ret;
        } else
                dev_info(&pdev->dev, "grabbed serial port IRQ\n");

        spin_lock_init(&micro->lock);
        INIT_LIST_HEAD(&micro->queue);
        platform_set_drvdata(pdev, micro);

        ret = mfd_add_devices(&pdev->dev, pdev->id, micro_cells,
                              ARRAY_SIZE(micro_cells), NULL, 0, NULL);
        if (ret) {
                dev_err(&pdev->dev, "error adding MFD cells");
                return ret;
        }

        /* Check version */
        ipaq_micro_get_version(micro);
        dev_info(&pdev->dev, "Atmel micro ASIC version %s\n", micro->version);
        ipaq_micro_eeprom_dump(micro);

        return 0;
}

static const struct dev_pm_ops micro_dev_pm_ops = {
        SET_SYSTEM_SLEEP_PM_OPS(NULL, micro_resume)
};

static struct platform_driver micro_device_driver = {
        .driver   = {
                .name   = "ipaq-h3xxx-micro",
                .pm     = &micro_dev_pm_ops,
                .suppress_bind_attrs = true,
        },
};
builtin_platform_driver_probe(micro_device_driver, micro_probe);