// SPDX-License-Identifier: ISC
/* Initialize Owl Emulation Devices
 *
 * Copyright (C) 2016 Christian Lamparter <chunkeey@gmail.com>
 * Copyright (C) 2016 Martin Blumenstingl <martin.blumenstingl@googlemail.com>
 *
 * Some devices (like the Cisco Meraki Z1 Cloud Managed Teleworker Gateway)
 * need to be able to initialize the PCIe wifi device. Normally, this is done
 * during the early stages as a pci quirk.
 * However, this isn't possible for devices which have the init code for the
 * Atheros chip stored on UBI Volume on NAND. Hence, this module can be used to
 * initialize the chip when the user-space is ready to extract the init code.
 */
#include <linux/module.h>
#include <linux/completion.h>
#include <linux/etherdevice.h>
#include <linux/firmware.h>
#include <linux/pci.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/nvmem-consumer.h>
#include <linux/workqueue.h>

struct owl_ctx {
        struct pci_dev *pdev;
        struct completion eeprom_load;
        struct work_struct work;
        struct nvmem_cell *cell;
};

#define EEPROM_FILENAME_LEN 100

#define AR5416_EEPROM_MAGIC 0xa55a

static int ath9k_pci_fixup(struct pci_dev *pdev, const u16 *cal_data,
                           size_t cal_len)
{
        void __iomem *mem;
        const void *cal_end = (void *)cal_data + cal_len;
        const struct {
                u16 reg;
                u16 low_val;
                u16 high_val;
        } __packed * data;
        u16 cmd;
        u32 bar0;
        bool swap_needed = false;

        /* also note that we are doing *u16 operations on the file */
        if (cal_len > 4096 || cal_len < 0x200 || (cal_len & 1) == 1) {
                dev_err(&pdev->dev, "eeprom has an invalid size.\n");
                return -EINVAL;
        }

        if (*cal_data != AR5416_EEPROM_MAGIC) {
                if (*cal_data != swab16(AR5416_EEPROM_MAGIC)) {
                        dev_err(&pdev->dev, "invalid calibration data\n");
                        return -EINVAL;
                }

                dev_dbg(&pdev->dev, "calibration data needs swapping\n");
                swap_needed = true;
        }

        dev_info(&pdev->dev, "fixup device configuration\n");

        mem = pci_iomap(pdev, 0, 0);
        if (!mem) {
                dev_err(&pdev->dev, "ioremap error\n");
                return -EINVAL;
        }

        pci_read_config_dword(pdev, PCI_BASE_ADDRESS_0, &bar0);
        pci_write_config_dword(pdev, PCI_BASE_ADDRESS_0,
                               pci_resource_start(pdev, 0));
        pci_read_config_word(pdev, PCI_COMMAND, &cmd);
        cmd |= PCI_COMMAND_MASTER | PCI_COMMAND_MEMORY;
        pci_write_config_word(pdev, PCI_COMMAND, cmd);

        /* set pointer to first reg address */
        for (data = (const void *)(cal_data + 3);
             (const void *)data <= cal_end && data->reg != (u16)~0;
             data++) {
                u32 val;
                u16 reg;

                reg = data->reg;
                val = data->low_val;
                val |= ((u32)data->high_val) << 16;

                if (swap_needed) {
                        reg = swab16(reg);
                        val = swahb32(val);
                }

                iowrite32(val, mem + reg);
                usleep_range(100, 120);
        }

        pci_read_config_word(pdev, PCI_COMMAND, &cmd);
        cmd &= ~(PCI_COMMAND_MASTER | PCI_COMMAND_MEMORY);
        pci_write_config_word(pdev, PCI_COMMAND, cmd);

        pci_write_config_dword(pdev, PCI_BASE_ADDRESS_0, bar0);
        pci_iounmap(pdev, mem);

        pci_disable_device(pdev);

        return 0;
}

static void owl_rescan(struct pci_dev *pdev)
{
        struct pci_bus *bus = pdev->bus;

        pci_lock_rescan_remove();
        pci_stop_and_remove_bus_device(pdev);
        /* the device should come back with the proper
         * ProductId. But we have to initiate a rescan.
         */
        pci_rescan_bus(bus);
        pci_unlock_rescan_remove();
}

static void owl_fw_cb(const struct firmware *fw, void *context)
{
        struct owl_ctx *ctx = context;

        complete(&ctx->eeprom_load);

        if (fw) {
                ath9k_pci_fixup(ctx->pdev, (const u16 *)fw->data, fw->size);
                owl_rescan(ctx->pdev);
        } else {
                dev_err(&ctx->pdev->dev, "no eeprom data received.\n");
        }
        release_firmware(fw);
}

static const char *owl_get_eeprom_name(struct pci_dev *pdev)
{
        struct device *dev = &pdev->dev;
        char *eeprom_name;

        dev_dbg(dev, "using auto-generated eeprom filename\n");

        eeprom_name = devm_kzalloc(dev, EEPROM_FILENAME_LEN, GFP_KERNEL);
        if (!eeprom_name)
                return NULL;

        /* this should match the pattern used in ath9k/init.c */
        scnprintf(eeprom_name, EEPROM_FILENAME_LEN, "ath9k-eeprom-pci-%s.bin",
                  dev_name(dev));

        return eeprom_name;
}

static void owl_nvmem_work(struct work_struct *work)
{
        struct owl_ctx *ctx = container_of(work, struct owl_ctx, work);
        void *buf;
        size_t len;

        complete(&ctx->eeprom_load);

        buf = nvmem_cell_read(ctx->cell, &len);
        if (!IS_ERR(buf)) {
                ath9k_pci_fixup(ctx->pdev, buf, len);
                kfree(buf);
                owl_rescan(ctx->pdev);
        } else {
                dev_err(&ctx->pdev->dev, "no nvmem data received.\n");
        }
}

static int owl_nvmem_probe(struct owl_ctx *ctx)
{
        int err;

        ctx->cell = devm_nvmem_cell_get(&ctx->pdev->dev, "calibration");
        if (IS_ERR(ctx->cell)) {
                err = PTR_ERR(ctx->cell);
                if (err == -ENOENT || err == -EOPNOTSUPP)
                        return 1; /* not present, try firmware_request */

                return err;
        }

        INIT_WORK(&ctx->work, owl_nvmem_work);
        schedule_work(&ctx->work);

        return 0;
}

static int owl_probe(struct pci_dev *pdev,
                     const struct pci_device_id *id)
{
        struct owl_ctx *ctx;
        const char *eeprom_name;
        int err = 0;

        if (pci_enable_device(pdev))
                return -EIO;

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

        init_completion(&ctx->eeprom_load);
        ctx->pdev = pdev;

        pci_set_drvdata(pdev, ctx);

        err = owl_nvmem_probe(ctx);
        if (err <= 0)
                return err;

        eeprom_name = owl_get_eeprom_name(pdev);
        if (!eeprom_name) {
                dev_err(&pdev->dev, "no eeprom filename found.\n");
                return -ENODEV;
        }

        err = request_firmware_nowait(THIS_MODULE, true, eeprom_name,
                                      &pdev->dev, GFP_KERNEL, ctx, owl_fw_cb);
        if (err)
                dev_err(&pdev->dev, "failed to request caldata (%d).\n", err);

        return err;
}

static void owl_remove(struct pci_dev *pdev)
{
        struct owl_ctx *ctx = pci_get_drvdata(pdev);

        if (ctx) {
                wait_for_completion(&ctx->eeprom_load);
                pci_set_drvdata(pdev, NULL);
        }
}

static const struct pci_device_id owl_pci_table[] = {
        { PCI_VDEVICE(ATHEROS, 0xff1c) }, /* PCIe */
        { PCI_VDEVICE(ATHEROS, 0xff1d) }, /* PCI */
        { },
};
MODULE_DEVICE_TABLE(pci, owl_pci_table);

static struct pci_driver owl_driver = {
        .name           = KBUILD_MODNAME,
        .id_table       = owl_pci_table,
        .probe          = owl_probe,
        .remove         = owl_remove,
};
module_pci_driver(owl_driver);
MODULE_AUTHOR("Christian Lamparter <chunkeey@gmail.com>");
MODULE_DESCRIPTION("External EEPROM data loader for Atheros AR500X to AR92XX");
MODULE_LICENSE("Dual BSD/GPL");