/*
 * FPGA Manager Driver for Altera Arria/Cyclone/Stratix CvP
 *
 * Copyright (C) 2017 DENX Software Engineering
 *
 * Anatolij Gustschin <agust@denx.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * Manage Altera FPGA firmware using PCIe CvP.
 * Firmware must be in binary "rbf" format.
 */

#include <linux/delay.h>
#include <linux/device.h>
#include <linux/fpga/fpga-mgr.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/sizes.h>

#define CVP_BAR         0       /* BAR used for data transfer in memory mode */
#define CVP_DUMMY_WR    244     /* dummy writes to clear CvP state machine */
#define TIMEOUT_US      2000    /* CVP STATUS timeout for USERMODE polling */

/* Vendor Specific Extended Capability Registers */
#define VSE_PCIE_EXT_CAP_ID             0x200
#define VSE_PCIE_EXT_CAP_ID_VAL         0x000b  /* 16bit */

#define VSE_CVP_STATUS                  0x21c   /* 32bit */
#define VSE_CVP_STATUS_CFG_RDY          BIT(18) /* CVP_CONFIG_READY */
#define VSE_CVP_STATUS_CFG_ERR          BIT(19) /* CVP_CONFIG_ERROR */
#define VSE_CVP_STATUS_CVP_EN           BIT(20) /* ctrl block is enabling CVP */
#define VSE_CVP_STATUS_USERMODE         BIT(21) /* USERMODE */
#define VSE_CVP_STATUS_CFG_DONE         BIT(23) /* CVP_CONFIG_DONE */
#define VSE_CVP_STATUS_PLD_CLK_IN_USE   BIT(24) /* PLD_CLK_IN_USE */

#define VSE_CVP_MODE_CTRL               0x220   /* 32bit */
#define VSE_CVP_MODE_CTRL_CVP_MODE      BIT(0)  /* CVP (1) or normal mode (0) */
#define VSE_CVP_MODE_CTRL_HIP_CLK_SEL   BIT(1) /* PMA (1) or fabric clock (0) */
#define VSE_CVP_MODE_CTRL_NUMCLKS_OFF   8       /* NUMCLKS bits offset */
#define VSE_CVP_MODE_CTRL_NUMCLKS_MASK  GENMASK(15, 8)

#define VSE_CVP_DATA                    0x228   /* 32bit */
#define VSE_CVP_PROG_CTRL               0x22c   /* 32bit */
#define VSE_CVP_PROG_CTRL_CONFIG        BIT(0)
#define VSE_CVP_PROG_CTRL_START_XFER    BIT(1)

#define VSE_UNCOR_ERR_STATUS            0x234   /* 32bit */
#define VSE_UNCOR_ERR_CVP_CFG_ERR       BIT(5)  /* CVP_CONFIG_ERROR_LATCHED */

#define DRV_NAME                "altera-cvp"
#define ALTERA_CVP_MGR_NAME     "Altera CvP FPGA Manager"

/* Optional CvP config error status check for debugging */
static bool altera_cvp_chkcfg;

struct altera_cvp_conf {
        struct fpga_manager     *mgr;
        struct pci_dev          *pci_dev;
        void __iomem            *map;
        void                    (*write_data)(struct altera_cvp_conf *, u32);
        char                    mgr_name[64];
        u8                      numclks;
};

static enum fpga_mgr_states altera_cvp_state(struct fpga_manager *mgr)
{
        struct altera_cvp_conf *conf = mgr->priv;
        u32 status;

        pci_read_config_dword(conf->pci_dev, VSE_CVP_STATUS, &status);

        if (status & VSE_CVP_STATUS_CFG_DONE)
                return FPGA_MGR_STATE_OPERATING;

        if (status & VSE_CVP_STATUS_CVP_EN)
                return FPGA_MGR_STATE_POWER_UP;

        return FPGA_MGR_STATE_UNKNOWN;
}

static void altera_cvp_write_data_iomem(struct altera_cvp_conf *conf, u32 val)
{
        writel(val, conf->map);
}

static void altera_cvp_write_data_config(struct altera_cvp_conf *conf, u32 val)
{
        pci_write_config_dword(conf->pci_dev, VSE_CVP_DATA, val);
}

/* switches between CvP clock and internal clock */
static void altera_cvp_dummy_write(struct altera_cvp_conf *conf)
{
        unsigned int i;
        u32 val;

        /* set 1 CVP clock cycle for every CVP Data Register Write */
        pci_read_config_dword(conf->pci_dev, VSE_CVP_MODE_CTRL, &val);
        val &= ~VSE_CVP_MODE_CTRL_NUMCLKS_MASK;
        val |= 1 << VSE_CVP_MODE_CTRL_NUMCLKS_OFF;
        pci_write_config_dword(conf->pci_dev, VSE_CVP_MODE_CTRL, val);

        for (i = 0; i < CVP_DUMMY_WR; i++)
                conf->write_data(conf, 0); /* dummy data, could be any value */
}

static int altera_cvp_wait_status(struct altera_cvp_conf *conf, u32 status_mask,
                                  u32 status_val, int timeout_us)
{
        unsigned int retries;
        u32 val;

        retries = timeout_us / 10;
        if (timeout_us % 10)
                retries++;

        do {
                pci_read_config_dword(conf->pci_dev, VSE_CVP_STATUS, &val);
                if ((val & status_mask) == status_val)
                        return 0;

                /* use small usleep value to re-check and break early */
                usleep_range(10, 11);
        } while (--retries);

        return -ETIMEDOUT;
}

static int altera_cvp_teardown(struct fpga_manager *mgr,
                               struct fpga_image_info *info)
{
        struct altera_cvp_conf *conf = mgr->priv;
        struct pci_dev *pdev = conf->pci_dev;
        int ret;
        u32 val;

        /* STEP 12 - reset START_XFER bit */
        pci_read_config_dword(pdev, VSE_CVP_PROG_CTRL, &val);
        val &= ~VSE_CVP_PROG_CTRL_START_XFER;
        pci_write_config_dword(pdev, VSE_CVP_PROG_CTRL, val);

        /* STEP 13 - reset CVP_CONFIG bit */
        val &= ~VSE_CVP_PROG_CTRL_CONFIG;
        pci_write_config_dword(pdev, VSE_CVP_PROG_CTRL, val);

        /*
         * STEP 14
         * - set CVP_NUMCLKS to 1 and then issue CVP_DUMMY_WR dummy
         *   writes to the HIP
         */
        altera_cvp_dummy_write(conf); /* from CVP clock to internal clock */

        /* STEP 15 - poll CVP_CONFIG_READY bit for 0 with 10us timeout */
        ret = altera_cvp_wait_status(conf, VSE_CVP_STATUS_CFG_RDY, 0, 10);
        if (ret)
                dev_err(&mgr->dev, "CFG_RDY == 0 timeout\n");

        return ret;
}

static int altera_cvp_write_init(struct fpga_manager *mgr,
                                 struct fpga_image_info *info,
                                 const char *buf, size_t count)
{
        struct altera_cvp_conf *conf = mgr->priv;
        struct pci_dev *pdev = conf->pci_dev;
        u32 iflags, val;
        int ret;

        iflags = info ? info->flags : 0;

        if (iflags & FPGA_MGR_PARTIAL_RECONFIG) {
                dev_err(&mgr->dev, "Partial reconfiguration not supported.\n");
                return -EINVAL;
        }

        /* Determine allowed clock to data ratio */
        if (iflags & FPGA_MGR_COMPRESSED_BITSTREAM)
                conf->numclks = 8; /* ratio for all compressed images */
        else if (iflags & FPGA_MGR_ENCRYPTED_BITSTREAM)
                conf->numclks = 4; /* for uncompressed and encrypted images */
        else
                conf->numclks = 1; /* for uncompressed and unencrypted images */

        /* STEP 1 - read CVP status and check CVP_EN flag */
        pci_read_config_dword(pdev, VSE_CVP_STATUS, &val);
        if (!(val & VSE_CVP_STATUS_CVP_EN)) {
                dev_err(&mgr->dev, "CVP mode off: 0x%04x\n", val);
                return -ENODEV;
        }

        if (val & VSE_CVP_STATUS_CFG_RDY) {
                dev_warn(&mgr->dev, "CvP already started, teardown first\n");
                ret = altera_cvp_teardown(mgr, info);
                if (ret)
                        return ret;
        }

        /*
         * STEP 2
         * - set HIP_CLK_SEL and CVP_MODE (must be set in the order mentioned)
         */
        /* switch from fabric to PMA clock */
        pci_read_config_dword(pdev, VSE_CVP_MODE_CTRL, &val);
        val |= VSE_CVP_MODE_CTRL_HIP_CLK_SEL;
        pci_write_config_dword(pdev, VSE_CVP_MODE_CTRL, val);

        /* set CVP mode */
        pci_read_config_dword(pdev, VSE_CVP_MODE_CTRL, &val);
        val |= VSE_CVP_MODE_CTRL_CVP_MODE;
        pci_write_config_dword(pdev, VSE_CVP_MODE_CTRL, val);

        /*
         * STEP 3
         * - set CVP_NUMCLKS to 1 and issue CVP_DUMMY_WR dummy writes to the HIP
         */
        altera_cvp_dummy_write(conf);

        /* STEP 4 - set CVP_CONFIG bit */
        pci_read_config_dword(pdev, VSE_CVP_PROG_CTRL, &val);
        /* request control block to begin transfer using CVP */
        val |= VSE_CVP_PROG_CTRL_CONFIG;
        pci_write_config_dword(pdev, VSE_CVP_PROG_CTRL, val);

        /* STEP 5 - poll CVP_CONFIG READY for 1 with 10us timeout */
        ret = altera_cvp_wait_status(conf, VSE_CVP_STATUS_CFG_RDY,
                                     VSE_CVP_STATUS_CFG_RDY, 10);
        if (ret) {
                dev_warn(&mgr->dev, "CFG_RDY == 1 timeout\n");
                return ret;
        }

        /*
         * STEP 6
         * - set CVP_NUMCLKS to 1 and issue CVP_DUMMY_WR dummy writes to the HIP
         */
        altera_cvp_dummy_write(conf);

        /* STEP 7 - set START_XFER */
        pci_read_config_dword(pdev, VSE_CVP_PROG_CTRL, &val);
        val |= VSE_CVP_PROG_CTRL_START_XFER;
        pci_write_config_dword(pdev, VSE_CVP_PROG_CTRL, val);

        /* STEP 8 - start transfer (set CVP_NUMCLKS for bitstream) */
        pci_read_config_dword(pdev, VSE_CVP_MODE_CTRL, &val);
        val &= ~VSE_CVP_MODE_CTRL_NUMCLKS_MASK;
        val |= conf->numclks << VSE_CVP_MODE_CTRL_NUMCLKS_OFF;
        pci_write_config_dword(pdev, VSE_CVP_MODE_CTRL, val);

        return 0;
}

static inline int altera_cvp_chk_error(struct fpga_manager *mgr, size_t bytes)
{
        struct altera_cvp_conf *conf = mgr->priv;
        u32 val;

        /* STEP 10 (optional) - check CVP_CONFIG_ERROR flag */
        pci_read_config_dword(conf->pci_dev, VSE_CVP_STATUS, &val);
        if (val & VSE_CVP_STATUS_CFG_ERR) {
                dev_err(&mgr->dev, "CVP_CONFIG_ERROR after %zu bytes!\n",
                        bytes);
                return -EPROTO;
        }
        return 0;
}

static int altera_cvp_write(struct fpga_manager *mgr, const char *buf,
                            size_t count)
{
        struct altera_cvp_conf *conf = mgr->priv;
        const u32 *data;
        size_t done, remaining;
        int status = 0;
        u32 mask;

        /* STEP 9 - write 32-bit data from RBF file to CVP data register */
        data = (u32 *)buf;
        remaining = count;
        done = 0;

        while (remaining >= 4) {
                conf->write_data(conf, *data++);
                done += 4;
                remaining -= 4;

                /*
                 * STEP 10 (optional) and STEP 11
                 * - check error flag
                 * - loop until data transfer completed
                 * Config images can be huge (more than 40 MiB), so
                 * only check after a new 4k data block has been written.
                 * This reduces the number of checks and speeds up the
                 * configuration process.
                 */
                if (altera_cvp_chkcfg && !(done % SZ_4K)) {
                        status = altera_cvp_chk_error(mgr, done);
                        if (status < 0)
                                return status;
                }
        }

        /* write up to 3 trailing bytes, if any */
        mask = BIT(remaining * 8) - 1;
        if (mask)
                conf->write_data(conf, *data & mask);

        if (altera_cvp_chkcfg)
                status = altera_cvp_chk_error(mgr, count);

        return status;
}

static int altera_cvp_write_complete(struct fpga_manager *mgr,
                                     struct fpga_image_info *info)
{
        struct altera_cvp_conf *conf = mgr->priv;
        struct pci_dev *pdev = conf->pci_dev;
        int ret;
        u32 mask;
        u32 val;

        ret = altera_cvp_teardown(mgr, info);
        if (ret)
                return ret;

        /* STEP 16 - check CVP_CONFIG_ERROR_LATCHED bit */
        pci_read_config_dword(pdev, VSE_UNCOR_ERR_STATUS, &val);
        if (val & VSE_UNCOR_ERR_CVP_CFG_ERR) {
                dev_err(&mgr->dev, "detected CVP_CONFIG_ERROR_LATCHED!\n");
                return -EPROTO;
        }

        /* STEP 17 - reset CVP_MODE and HIP_CLK_SEL bit */
        pci_read_config_dword(pdev, VSE_CVP_MODE_CTRL, &val);
        val &= ~VSE_CVP_MODE_CTRL_HIP_CLK_SEL;
        val &= ~VSE_CVP_MODE_CTRL_CVP_MODE;
        pci_write_config_dword(pdev, VSE_CVP_MODE_CTRL, val);

        /* STEP 18 - poll PLD_CLK_IN_USE and USER_MODE bits */
        mask = VSE_CVP_STATUS_PLD_CLK_IN_USE | VSE_CVP_STATUS_USERMODE;
        ret = altera_cvp_wait_status(conf, mask, mask, TIMEOUT_US);
        if (ret)
                dev_err(&mgr->dev, "PLD_CLK_IN_USE|USERMODE timeout\n");

        return ret;
}

static const struct fpga_manager_ops altera_cvp_ops = {
        .state          = altera_cvp_state,
        .write_init     = altera_cvp_write_init,
        .write          = altera_cvp_write,
        .write_complete = altera_cvp_write_complete,
};

static ssize_t chkcfg_show(struct device_driver *dev, char *buf)
{
        return snprintf(buf, 3, "%d\n", altera_cvp_chkcfg);
}

static ssize_t chkcfg_store(struct device_driver *drv, const char *buf,
                            size_t count)
{
        int ret;

        ret = kstrtobool(buf, &altera_cvp_chkcfg);
        if (ret)
                return ret;

        return count;
}

static DRIVER_ATTR_RW(chkcfg);

static int altera_cvp_probe(struct pci_dev *pdev,
                            const struct pci_device_id *dev_id);
static void altera_cvp_remove(struct pci_dev *pdev);

static struct pci_device_id altera_cvp_id_tbl[] = {
        { PCI_VDEVICE(ALTERA, PCI_ANY_ID) },
        { }
};
MODULE_DEVICE_TABLE(pci, altera_cvp_id_tbl);

static struct pci_driver altera_cvp_driver = {
        .name   = DRV_NAME,
        .id_table = altera_cvp_id_tbl,
        .probe  = altera_cvp_probe,
        .remove = altera_cvp_remove,
};

static int altera_cvp_probe(struct pci_dev *pdev,
                            const struct pci_device_id *dev_id)
{
        struct altera_cvp_conf *conf;
        u16 cmd, val;
        int ret;

        /*
         * First check if this is the expected FPGA device. PCI config
         * space access works without enabling the PCI device, memory
         * space access is enabled further down.
         */
        pci_read_config_word(pdev, VSE_PCIE_EXT_CAP_ID, &val);
        if (val != VSE_PCIE_EXT_CAP_ID_VAL) {
                dev_err(&pdev->dev, "Wrong EXT_CAP_ID value 0x%x\n", val);
                return -ENODEV;
        }

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

        /*
         * Enable memory BAR access. We cannot use pci_enable_device() here
         * because it will make the driver unusable with FPGA devices that
         * have additional big IOMEM resources (e.g. 4GiB BARs) on 32-bit
         * platform. Such BARs will not have an assigned address range and
         * pci_enable_device() will fail, complaining about not claimed BAR,
         * even if the concerned BAR is not needed for FPGA configuration
         * at all. Thus, enable the device via PCI config space command.
         */
        pci_read_config_word(pdev, PCI_COMMAND, &cmd);
        if (!(cmd & PCI_COMMAND_MEMORY)) {
                cmd |= PCI_COMMAND_MEMORY;
                pci_write_config_word(pdev, PCI_COMMAND, cmd);
        }

        ret = pci_request_region(pdev, CVP_BAR, "CVP");
        if (ret) {
                dev_err(&pdev->dev, "Requesting CVP BAR region failed\n");
                goto err_disable;
        }

        conf->pci_dev = pdev;
        conf->write_data = altera_cvp_write_data_iomem;

        conf->map = pci_iomap(pdev, CVP_BAR, 0);
        if (!conf->map) {
                dev_warn(&pdev->dev, "Mapping CVP BAR failed\n");
                conf->write_data = altera_cvp_write_data_config;
        }

        snprintf(conf->mgr_name, sizeof(conf->mgr_name), "%s @%s",
                 ALTERA_CVP_MGR_NAME, pci_name(pdev));

        ret = fpga_mgr_register(&pdev->dev, conf->mgr_name,
                                &altera_cvp_ops, conf);
        if (ret)
                goto err_unmap;

        ret = driver_create_file(&altera_cvp_driver.driver,
                                 &driver_attr_chkcfg);
        if (ret) {
                dev_err(&pdev->dev, "Can't create sysfs chkcfg file\n");
                fpga_mgr_unregister(&pdev->dev);
                goto err_unmap;
        }

        return 0;

err_unmap:
        pci_iounmap(pdev, conf->map);
        pci_release_region(pdev, CVP_BAR);
err_disable:
        cmd &= ~PCI_COMMAND_MEMORY;
        pci_write_config_word(pdev, PCI_COMMAND, cmd);
        return ret;
}

static void altera_cvp_remove(struct pci_dev *pdev)
{
        struct fpga_manager *mgr = pci_get_drvdata(pdev);
        struct altera_cvp_conf *conf = mgr->priv;
        u16 cmd;

        driver_remove_file(&altera_cvp_driver.driver, &driver_attr_chkcfg);
        fpga_mgr_unregister(&pdev->dev);
        pci_iounmap(pdev, conf->map);
        pci_release_region(pdev, CVP_BAR);
        pci_read_config_word(pdev, PCI_COMMAND, &cmd);
        cmd &= ~PCI_COMMAND_MEMORY;
        pci_write_config_word(pdev, PCI_COMMAND, cmd);
}

module_pci_driver(altera_cvp_driver);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Anatolij Gustschin <agust@denx.de>");
MODULE_DESCRIPTION("Module to load Altera FPGA over CvP");