root/drivers/fpga/lattice-sysconfig.c
// SPDX-License-Identifier: GPL-2.0
/*
 * Lattice FPGA sysCONFIG interface functions independent of port type.
 */

#include <linux/delay.h>
#include <linux/fpga/fpga-mgr.h>
#include <linux/gpio/consumer.h>
#include <linux/iopoll.h>

#include "lattice-sysconfig.h"

static int sysconfig_cmd_write(struct sysconfig_priv *priv, const void *buf,
                               size_t buf_len)
{
        return priv->command_transfer(priv, buf, buf_len, NULL, 0);
}

static int sysconfig_cmd_read(struct sysconfig_priv *priv, const void *tx_buf,
                              size_t tx_len, void *rx_buf, size_t rx_len)
{
        return priv->command_transfer(priv, tx_buf, tx_len, rx_buf, rx_len);
}

static int sysconfig_read_busy(struct sysconfig_priv *priv)
{
        const u8 lsc_check_busy[] = SYSCONFIG_LSC_CHECK_BUSY;
        u8 busy;
        int ret;

        ret = sysconfig_cmd_read(priv, lsc_check_busy, sizeof(lsc_check_busy),
                                 &busy, sizeof(busy));

        return ret ? : busy;
}

static int sysconfig_poll_busy(struct sysconfig_priv *priv)
{
        int ret, busy;

        ret = read_poll_timeout(sysconfig_read_busy, busy, busy <= 0,
                                SYSCONFIG_POLL_INTERVAL_US,
                                SYSCONFIG_POLL_BUSY_TIMEOUT_US, false, priv);

        return ret ? : busy;
}

static int sysconfig_read_status(struct sysconfig_priv *priv, u32 *status)
{
        const u8 lsc_read_status[] = SYSCONFIG_LSC_READ_STATUS;
        __be32 device_status;
        int ret;

        ret = sysconfig_cmd_read(priv, lsc_read_status, sizeof(lsc_read_status),
                                 &device_status, sizeof(device_status));
        if (ret)
                return ret;

        *status = be32_to_cpu(device_status);

        return 0;
}

static int sysconfig_poll_status(struct sysconfig_priv *priv, u32 *status)
{
        int ret = sysconfig_poll_busy(priv);

        if (ret)
                return ret;

        return sysconfig_read_status(priv, status);
}

static int sysconfig_poll_gpio(struct gpio_desc *gpio, bool is_active)
{
        int ret, val;

        ret = read_poll_timeout(gpiod_get_value, val,
                                val < 0 || !!val == is_active,
                                SYSCONFIG_POLL_INTERVAL_US,
                                SYSCONFIG_POLL_GPIO_TIMEOUT_US, false, gpio);

        if (val < 0)
                return val;

        return ret;
}

static int sysconfig_gpio_refresh(struct sysconfig_priv *priv)
{
        struct gpio_desc *program = priv->program;
        struct gpio_desc *init = priv->init;
        struct gpio_desc *done = priv->done;
        int ret;

        /* Enter init mode */
        gpiod_set_value(program, 1);

        ret = sysconfig_poll_gpio(init, true);
        if (!ret)
                ret = sysconfig_poll_gpio(done, false);

        if (ret)
                return ret;

        /* Enter program mode */
        gpiod_set_value(program, 0);

        return sysconfig_poll_gpio(init, false);
}

static int sysconfig_lsc_refresh(struct sysconfig_priv *priv)
{
        static const u8 lsc_refresh[] = SYSCONFIG_LSC_REFRESH;
        int ret;

        ret = sysconfig_cmd_write(priv, lsc_refresh, sizeof(lsc_refresh));
        if (ret)
                return ret;

        usleep_range(4000, 8000);

        return 0;
}

static int sysconfig_refresh(struct sysconfig_priv *priv)
{
        struct gpio_desc *program = priv->program;
        struct gpio_desc *init = priv->init;
        struct gpio_desc *done = priv->done;

        if (program && init && done)
                return sysconfig_gpio_refresh(priv);

        return sysconfig_lsc_refresh(priv);
}

static int sysconfig_isc_enable(struct sysconfig_priv *priv)
{
        u8 isc_enable[] = SYSCONFIG_ISC_ENABLE;
        u32 status;
        int ret;

        ret = sysconfig_cmd_write(priv, isc_enable, sizeof(isc_enable));
        if (ret)
                return ret;

        ret = sysconfig_poll_status(priv, &status);
        if (ret)
                return ret;

        if (status & SYSCONFIG_STATUS_FAIL)
                return -EFAULT;

        return 0;
}

static int sysconfig_isc_erase(struct sysconfig_priv *priv)
{
        u8 isc_erase[] = SYSCONFIG_ISC_ERASE;
        u32 status;
        int ret;

        ret = sysconfig_cmd_write(priv, isc_erase, sizeof(isc_erase));
        if (ret)
                return ret;

        ret = sysconfig_poll_status(priv, &status);
        if (ret)
                return ret;

        if (status & SYSCONFIG_STATUS_FAIL)
                return -EFAULT;

        return 0;
}

static int sysconfig_isc_init(struct sysconfig_priv *priv)
{
        int ret = sysconfig_isc_enable(priv);

        if (ret)
                return ret;

        return sysconfig_isc_erase(priv);
}

static int sysconfig_lsc_init_addr(struct sysconfig_priv *priv)
{
        const u8 lsc_init_addr[] = SYSCONFIG_LSC_INIT_ADDR;

        return sysconfig_cmd_write(priv, lsc_init_addr, sizeof(lsc_init_addr));
}

static int sysconfig_burst_write_init(struct sysconfig_priv *priv)
{
        return priv->bitstream_burst_write_init(priv);
}

static int sysconfig_burst_write_complete(struct sysconfig_priv *priv)
{
        return priv->bitstream_burst_write_complete(priv);
}

static int sysconfig_bitstream_burst_write(struct sysconfig_priv *priv,
                                           const char *buf, size_t count)
{
        int ret = priv->bitstream_burst_write(priv, buf, count);

        if (ret)
                sysconfig_burst_write_complete(priv);

        return ret;
}

static int sysconfig_isc_disable(struct sysconfig_priv *priv)
{
        const u8 isc_disable[] = SYSCONFIG_ISC_DISABLE;

        return sysconfig_cmd_write(priv, isc_disable, sizeof(isc_disable));
}

static void sysconfig_cleanup(struct sysconfig_priv *priv)
{
        sysconfig_isc_erase(priv);
        sysconfig_refresh(priv);
}

static int sysconfig_isc_finish(struct sysconfig_priv *priv)
{
        struct gpio_desc *done_gpio = priv->done;
        u32 status;
        int ret;

        if (done_gpio) {
                ret = sysconfig_isc_disable(priv);
                if (ret)
                        return ret;

                return sysconfig_poll_gpio(done_gpio, true);
        }

        ret = sysconfig_poll_status(priv, &status);
        if (ret)
                return ret;

        if ((status & SYSCONFIG_STATUS_DONE) &&
            !(status & SYSCONFIG_STATUS_BUSY) &&
            !(status & SYSCONFIG_STATUS_ERR))
                return sysconfig_isc_disable(priv);

        return -EFAULT;
}

static enum fpga_mgr_states sysconfig_ops_state(struct fpga_manager *mgr)
{
        struct sysconfig_priv *priv = mgr->priv;
        struct gpio_desc *done = priv->done;
        u32 status;
        int ret;

        if (done && (gpiod_get_value(done) > 0))
                return FPGA_MGR_STATE_OPERATING;

        ret = sysconfig_read_status(priv, &status);
        if (!ret && (status & SYSCONFIG_STATUS_DONE))
                return FPGA_MGR_STATE_OPERATING;

        return FPGA_MGR_STATE_UNKNOWN;
}

static int sysconfig_ops_write_init(struct fpga_manager *mgr,
                                    struct fpga_image_info *info,
                                    const char *buf, size_t count)
{
        struct sysconfig_priv *priv = mgr->priv;
        struct device *dev = &mgr->dev;
        int ret;

        if (info->flags & FPGA_MGR_PARTIAL_RECONFIG) {
                dev_err(dev, "Partial reconfiguration is not supported\n");
                return -EOPNOTSUPP;
        }

        /* Enter program mode */
        ret = sysconfig_refresh(priv);
        if (ret) {
                dev_err(dev, "Failed to go to program mode\n");
                return ret;
        }

        /* Enter ISC mode */
        ret = sysconfig_isc_init(priv);
        if (ret) {
                dev_err(dev, "Failed to go to ISC mode\n");
                return ret;
        }

        /* Initialize the Address Shift Register */
        ret = sysconfig_lsc_init_addr(priv);
        if (ret) {
                dev_err(dev,
                        "Failed to initialize the Address Shift Register\n");
                return ret;
        }

        /* Prepare for bitstream burst write */
        ret = sysconfig_burst_write_init(priv);
        if (ret)
                dev_err(dev, "Failed to prepare for bitstream burst write\n");

        return ret;
}

static int sysconfig_ops_write(struct fpga_manager *mgr, const char *buf,
                               size_t count)
{
        return sysconfig_bitstream_burst_write(mgr->priv, buf, count);
}

static int sysconfig_ops_write_complete(struct fpga_manager *mgr,
                                        struct fpga_image_info *info)
{
        struct sysconfig_priv *priv = mgr->priv;
        struct device *dev = &mgr->dev;
        int ret;

        ret = sysconfig_burst_write_complete(priv);
        if (!ret)
                ret = sysconfig_poll_busy(priv);

        if (ret) {
                dev_err(dev, "Error while waiting bitstream write to finish\n");
                goto fail;
        }

        ret = sysconfig_isc_finish(priv);

fail:
        if (ret)
                sysconfig_cleanup(priv);

        return ret;
}

static const struct fpga_manager_ops sysconfig_fpga_mgr_ops = {
        .state = sysconfig_ops_state,
        .write_init = sysconfig_ops_write_init,
        .write = sysconfig_ops_write,
        .write_complete = sysconfig_ops_write_complete,
};

int sysconfig_probe(struct sysconfig_priv *priv)
{
        struct gpio_desc *program, *init, *done;
        struct device *dev = priv->dev;
        struct fpga_manager *mgr;

        if (!dev)
                return -ENODEV;

        if (!priv->command_transfer ||
            !priv->bitstream_burst_write_init ||
            !priv->bitstream_burst_write ||
            !priv->bitstream_burst_write_complete) {
                dev_err(dev, "Essential callback is missing\n");
                return -EINVAL;
        }

        program = devm_gpiod_get_optional(dev, "program", GPIOD_OUT_LOW);
        if (IS_ERR(program))
                return dev_err_probe(dev, PTR_ERR(program),
                                     "Failed to get PROGRAM GPIO\n");

        init = devm_gpiod_get_optional(dev, "init", GPIOD_IN);
        if (IS_ERR(init))
                return dev_err_probe(dev, PTR_ERR(init),
                                     "Failed to get INIT GPIO\n");

        done = devm_gpiod_get_optional(dev, "done", GPIOD_IN);
        if (IS_ERR(done))
                return dev_err_probe(dev, PTR_ERR(done),
                                     "Failed to get DONE GPIO\n");

        priv->program = program;
        priv->init = init;
        priv->done = done;

        mgr = devm_fpga_mgr_register(dev, "Lattice sysCONFIG FPGA Manager",
                                     &sysconfig_fpga_mgr_ops, priv);

        return PTR_ERR_OR_ZERO(mgr);
}
EXPORT_SYMBOL(sysconfig_probe);

MODULE_DESCRIPTION("Lattice sysCONFIG FPGA Manager Core");
MODULE_LICENSE("GPL");