// SPDX-License-Identifier: GPL-2.0
// LPC interface for ChromeOS Embedded Controller
//
// Copyright (C) 2012-2015 Google, Inc
//
// This driver uses the ChromeOS EC byte-level message-based protocol for
// communicating the keyboard state (which keys are pressed) from a keyboard EC
// to the AP over some bus (such as i2c, lpc, spi).  The EC does debouncing,
// but everything else (including deghosting) is done here.  The main
// motivation for this is to keep the EC firmware as simple as possible, since
// it cannot be easily upgraded and EC flash/IRAM space is relatively
// expensive.

#include <linux/acpi.h>
#include <linux/dmi.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/interrupt.h>
#include <linux/mfd/cros_ec.h>
#include <linux/mfd/cros_ec_commands.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/printk.h>
#include <linux/suspend.h>

#include "cros_ec_lpc_mec.h"

#define DRV_NAME "cros_ec_lpcs"
#define ACPI_DRV_NAME "GOOG0004"

/* True if ACPI device is present */
static bool cros_ec_lpc_acpi_device_found;

/**
 * struct lpc_driver_ops - LPC driver operations
 * @read: Copy length bytes from EC address offset into buffer dest. Returns
 *        the 8-bit checksum of all bytes read.
 * @write: Copy length bytes from buffer msg into EC address offset. Returns
 *         the 8-bit checksum of all bytes written.
 */
struct lpc_driver_ops {
        u8 (*read)(unsigned int offset, unsigned int length, u8 *dest);
        u8 (*write)(unsigned int offset, unsigned int length, const u8 *msg);
};

static struct lpc_driver_ops cros_ec_lpc_ops = { };

/*
 * A generic instance of the read function of struct lpc_driver_ops, used for
 * the LPC EC.
 */
static u8 cros_ec_lpc_read_bytes(unsigned int offset, unsigned int length,
                                 u8 *dest)
{
        int sum = 0;
        int i;

        for (i = 0; i < length; ++i) {
                dest[i] = inb(offset + i);
                sum += dest[i];
        }

        /* Return checksum of all bytes read */
        return sum;
}

/*
 * A generic instance of the write function of struct lpc_driver_ops, used for
 * the LPC EC.
 */
static u8 cros_ec_lpc_write_bytes(unsigned int offset, unsigned int length,
                                  const u8 *msg)
{
        int sum = 0;
        int i;

        for (i = 0; i < length; ++i) {
                outb(msg[i], offset + i);
                sum += msg[i];
        }

        /* Return checksum of all bytes written */
        return sum;
}

/*
 * An instance of the read function of struct lpc_driver_ops, used for the
 * MEC variant of LPC EC.
 */
static u8 cros_ec_lpc_mec_read_bytes(unsigned int offset, unsigned int length,
                                     u8 *dest)
{
        int in_range = cros_ec_lpc_mec_in_range(offset, length);

        if (in_range < 0)
                return 0;

        return in_range ?
                cros_ec_lpc_io_bytes_mec(MEC_IO_READ,
                                         offset - EC_HOST_CMD_REGION0,
                                         length, dest) :
                cros_ec_lpc_read_bytes(offset, length, dest);
}

/*
 * An instance of the write function of struct lpc_driver_ops, used for the
 * MEC variant of LPC EC.
 */
static u8 cros_ec_lpc_mec_write_bytes(unsigned int offset, unsigned int length,
                                      const u8 *msg)
{
        int in_range = cros_ec_lpc_mec_in_range(offset, length);

        if (in_range < 0)
                return 0;

        return in_range ?
                cros_ec_lpc_io_bytes_mec(MEC_IO_WRITE,
                                         offset - EC_HOST_CMD_REGION0,
                                         length, (u8 *)msg) :
                cros_ec_lpc_write_bytes(offset, length, msg);
}

static int ec_response_timed_out(void)
{
        unsigned long one_second = jiffies + HZ;
        u8 data;

        usleep_range(200, 300);
        do {
                if (!(cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_CMD, 1, &data) &
                    EC_LPC_STATUS_BUSY_MASK))
                        return 0;
                usleep_range(100, 200);
        } while (time_before(jiffies, one_second));

        return 1;
}

static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
                                struct cros_ec_command *msg)
{
        struct ec_host_response response;
        u8 sum;
        int ret = 0;
        u8 *dout;

        ret = cros_ec_prepare_tx(ec, msg);

        /* Write buffer */
        cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_PACKET, ret, ec->dout);

        /* Here we go */
        sum = EC_COMMAND_PROTOCOL_3;
        cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_CMD, 1, &sum);

        if (ec_response_timed_out()) {
                dev_warn(ec->dev, "EC responsed timed out\n");
                ret = -EIO;
                goto done;
        }

        /* Check result */
        msg->result = cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_DATA, 1, &sum);
        ret = cros_ec_check_result(ec, msg);
        if (ret)
                goto done;

        /* Read back response */
        dout = (u8 *)&response;
        sum = cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_PACKET, sizeof(response),
                                   dout);

        msg->result = response.result;

        if (response.data_len > msg->insize) {
                dev_err(ec->dev,
                        "packet too long (%d bytes, expected %d)",
                        response.data_len, msg->insize);
                ret = -EMSGSIZE;
                goto done;
        }

        /* Read response and process checksum */
        sum += cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_PACKET +
                                    sizeof(response), response.data_len,
                                    msg->data);

        if (sum) {
                dev_err(ec->dev,
                        "bad packet checksum %02x\n",
                        response.checksum);
                ret = -EBADMSG;
                goto done;
        }

        /* Return actual amount of data received */
        ret = response.data_len;
done:
        return ret;
}

static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
                                struct cros_ec_command *msg)
{
        struct ec_lpc_host_args args;
        u8 sum;
        int ret = 0;

        if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE ||
            msg->insize > EC_PROTO2_MAX_PARAM_SIZE) {
                dev_err(ec->dev,
                        "invalid buffer sizes (out %d, in %d)\n",
                        msg->outsize, msg->insize);
                return -EINVAL;
        }

        /* Now actually send the command to the EC and get the result */
        args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
        args.command_version = msg->version;
        args.data_size = msg->outsize;

        /* Initialize checksum */
        sum = msg->command + args.flags + args.command_version + args.data_size;

        /* Copy data and update checksum */
        sum += cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_PARAM, msg->outsize,
                                     msg->data);

        /* Finalize checksum and write args */
        args.checksum = sum;
        cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
                              (u8 *)&args);

        /* Here we go */
        sum = msg->command;
        cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_CMD, 1, &sum);

        if (ec_response_timed_out()) {
                dev_warn(ec->dev, "EC responsed timed out\n");
                ret = -EIO;
                goto done;
        }

        /* Check result */
        msg->result = cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_DATA, 1, &sum);
        ret = cros_ec_check_result(ec, msg);
        if (ret)
                goto done;

        /* Read back args */
        cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_ARGS, sizeof(args), (u8 *)&args);

        if (args.data_size > msg->insize) {
                dev_err(ec->dev,
                        "packet too long (%d bytes, expected %d)",
                        args.data_size, msg->insize);
                ret = -ENOSPC;
                goto done;
        }

        /* Start calculating response checksum */
        sum = msg->command + args.flags + args.command_version + args.data_size;

        /* Read response and update checksum */
        sum += cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_PARAM, args.data_size,
                                    msg->data);

        /* Verify checksum */
        if (args.checksum != sum) {
                dev_err(ec->dev,
                        "bad packet checksum, expected %02x, got %02x\n",
                        args.checksum, sum);
                ret = -EBADMSG;
                goto done;
        }

        /* Return actual amount of data received */
        ret = args.data_size;
done:
        return ret;
}

/* Returns num bytes read, or negative on error. Doesn't need locking. */
static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
                               unsigned int bytes, void *dest)
{
        int i = offset;
        char *s = dest;
        int cnt = 0;

        if (offset >= EC_MEMMAP_SIZE - bytes)
                return -EINVAL;

        /* fixed length */
        if (bytes) {
                cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + offset, bytes, s);
                return bytes;
        }

        /* string */
        for (; i < EC_MEMMAP_SIZE; i++, s++) {
                cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + i, 1, s);
                cnt++;
                if (!*s)
                        break;
        }

        return cnt;
}

static void cros_ec_lpc_acpi_notify(acpi_handle device, u32 value, void *data)
{
        struct cros_ec_device *ec_dev = data;

        if (ec_dev->mkbp_event_supported &&
            cros_ec_get_next_event(ec_dev, NULL) > 0)
                blocking_notifier_call_chain(&ec_dev->event_notifier, 0,
                                             ec_dev);

        if (value == ACPI_NOTIFY_DEVICE_WAKE)
                pm_system_wakeup();
}

static int cros_ec_lpc_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct acpi_device *adev;
        acpi_status status;
        struct cros_ec_device *ec_dev;
        u8 buf[2];
        int irq, ret;

        if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
                                 dev_name(dev))) {
                dev_err(dev, "couldn't reserve memmap region\n");
                return -EBUSY;
        }

        /*
         * Read the mapped ID twice, the first one is assuming the
         * EC is a Microchip Embedded Controller (MEC) variant, if the
         * protocol fails, fallback to the non MEC variant and try to
         * read again the ID.
         */
        cros_ec_lpc_ops.read = cros_ec_lpc_mec_read_bytes;
        cros_ec_lpc_ops.write = cros_ec_lpc_mec_write_bytes;
        cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2, buf);
        if (buf[0] != 'E' || buf[1] != 'C') {
                /* Re-assign read/write operations for the non MEC variant */
                cros_ec_lpc_ops.read = cros_ec_lpc_read_bytes;
                cros_ec_lpc_ops.write = cros_ec_lpc_write_bytes;
                cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2,
                                     buf);
                if (buf[0] != 'E' || buf[1] != 'C') {
                        dev_err(dev, "EC ID not detected\n");
                        return -ENODEV;
                }
        }

        if (!devm_request_region(dev, EC_HOST_CMD_REGION0,
                                 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
                dev_err(dev, "couldn't reserve region0\n");
                return -EBUSY;
        }
        if (!devm_request_region(dev, EC_HOST_CMD_REGION1,
                                 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
                dev_err(dev, "couldn't reserve region1\n");
                return -EBUSY;
        }

        ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
        if (!ec_dev)
                return -ENOMEM;

        platform_set_drvdata(pdev, ec_dev);
        ec_dev->dev = dev;
        ec_dev->phys_name = dev_name(dev);
        ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
        ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
        ec_dev->cmd_readmem = cros_ec_lpc_readmem;
        ec_dev->din_size = sizeof(struct ec_host_response) +
                           sizeof(struct ec_response_get_protocol_info);
        ec_dev->dout_size = sizeof(struct ec_host_request);

        /*
         * Some boards do not have an IRQ allotted for cros_ec_lpc,
         * which makes ENXIO an expected (and safe) scenario.
         */
        irq = platform_get_irq(pdev, 0);
        if (irq > 0)
                ec_dev->irq = irq;
        else if (irq != -ENXIO) {
                dev_err(dev, "couldn't retrieve IRQ number (%d)\n", irq);
                return irq;
        }

        ret = cros_ec_register(ec_dev);
        if (ret) {
                dev_err(dev, "couldn't register ec_dev (%d)\n", ret);
                return ret;
        }

        /*
         * Connect a notify handler to process MKBP messages if we have a
         * companion ACPI device.
         */
        adev = ACPI_COMPANION(dev);
        if (adev) {
                status = acpi_install_notify_handler(adev->handle,
                                                     ACPI_ALL_NOTIFY,
                                                     cros_ec_lpc_acpi_notify,
                                                     ec_dev);
                if (ACPI_FAILURE(status))
                        dev_warn(dev, "Failed to register notifier %08x\n",
                                 status);
        }

        return 0;
}

static int cros_ec_lpc_remove(struct platform_device *pdev)
{
        struct acpi_device *adev;

        adev = ACPI_COMPANION(&pdev->dev);
        if (adev)
                acpi_remove_notify_handler(adev->handle, ACPI_ALL_NOTIFY,
                                           cros_ec_lpc_acpi_notify);

        return 0;
}

static const struct acpi_device_id cros_ec_lpc_acpi_device_ids[] = {
        { ACPI_DRV_NAME, 0 },
        { }
};
MODULE_DEVICE_TABLE(acpi, cros_ec_lpc_acpi_device_ids);

static const struct dmi_system_id cros_ec_lpc_dmi_table[] __initconst = {
        {
                /*
                 * Today all Chromebooks/boxes ship with Google_* as version and
                 * coreboot as bios vendor. No other systems with this
                 * combination are known to date.
                 */
                .matches = {
                        DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
                        DMI_MATCH(DMI_BIOS_VERSION, "Google_"),
                },
        },
        {
                /*
                 * If the box is running custom coreboot firmware then the
                 * DMI BIOS version string will not be matched by "Google_",
                 * but the system vendor string will still be matched by
                 * "GOOGLE".
                 */
                .matches = {
                        DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
                        DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
                },
        },
        {
                /* x86-link, the Chromebook Pixel. */
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Link"),
                },
        },
        {
                /* x86-samus, the Chromebook Pixel 2. */
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Samus"),
                },
        },
        {
                /* x86-peppy, the Acer C720 Chromebook. */
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Peppy"),
                },
        },
        {
                /* x86-glimmer, the Lenovo Thinkpad Yoga 11e. */
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Glimmer"),
                },
        },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table);

#ifdef CONFIG_PM_SLEEP
static int cros_ec_lpc_suspend(struct device *dev)
{
        struct cros_ec_device *ec_dev = dev_get_drvdata(dev);

        return cros_ec_suspend(ec_dev);
}

static int cros_ec_lpc_resume(struct device *dev)
{
        struct cros_ec_device *ec_dev = dev_get_drvdata(dev);

        return cros_ec_resume(ec_dev);
}
#endif

static const struct dev_pm_ops cros_ec_lpc_pm_ops = {
        SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_lpc_suspend, cros_ec_lpc_resume)
};

static struct platform_driver cros_ec_lpc_driver = {
        .driver = {
                .name = DRV_NAME,
                .acpi_match_table = cros_ec_lpc_acpi_device_ids,
                .pm = &cros_ec_lpc_pm_ops,
        },
        .probe = cros_ec_lpc_probe,
        .remove = cros_ec_lpc_remove,
};

static struct platform_device cros_ec_lpc_device = {
        .name = DRV_NAME
};

static acpi_status cros_ec_lpc_parse_device(acpi_handle handle, u32 level,
                                            void *context, void **retval)
{
        *(bool *)context = true;
        return AE_CTRL_TERMINATE;
}

static int __init cros_ec_lpc_init(void)
{
        int ret;
        acpi_status status;

        status = acpi_get_devices(ACPI_DRV_NAME, cros_ec_lpc_parse_device,
                                  &cros_ec_lpc_acpi_device_found, NULL);
        if (ACPI_FAILURE(status))
                pr_warn(DRV_NAME ": Looking for %s failed\n", ACPI_DRV_NAME);

        if (!cros_ec_lpc_acpi_device_found &&
            !dmi_check_system(cros_ec_lpc_dmi_table)) {
                pr_err(DRV_NAME ": unsupported system.\n");
                return -ENODEV;
        }

        cros_ec_lpc_mec_init(EC_HOST_CMD_REGION0,
                             EC_LPC_ADDR_MEMMAP + EC_MEMMAP_SIZE);

        /* Register the driver */
        ret = platform_driver_register(&cros_ec_lpc_driver);
        if (ret) {
                pr_err(DRV_NAME ": can't register driver: %d\n", ret);
                cros_ec_lpc_mec_destroy();
                return ret;
        }

        if (!cros_ec_lpc_acpi_device_found) {
                /* Register the device, and it'll get hooked up automatically */
                ret = platform_device_register(&cros_ec_lpc_device);
                if (ret) {
                        pr_err(DRV_NAME ": can't register device: %d\n", ret);
                        platform_driver_unregister(&cros_ec_lpc_driver);
                        cros_ec_lpc_mec_destroy();
                }
        }

        return ret;
}

static void __exit cros_ec_lpc_exit(void)
{
        if (!cros_ec_lpc_acpi_device_found)
                platform_device_unregister(&cros_ec_lpc_device);
        platform_driver_unregister(&cros_ec_lpc_driver);
        cros_ec_lpc_mec_destroy();
}

module_init(cros_ec_lpc_init);
module_exit(cros_ec_lpc_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("ChromeOS EC LPC driver");