/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2013 Thomas Skibo
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Zynq-700 SLCR driver.  Provides hooks for cpu_reset and PL control stuff.
 * In the future, maybe MIO control, clock control, etc. could go here.
 *
 * Reference: Zynq-7000 All Programmable SoC Technical Reference Manual.
 * (v1.4) November 16, 2012.  Xilinx doc UG585.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/resource.h>
#include <sys/stdarg.h>
#include <sys/sysctl.h>
#include <sys/rman.h>

#include <machine/bus.h>
#include <machine/resource.h>

#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>

#include <arm/xilinx/zy7_slcr.h>

struct zy7_slcr_softc {
        device_t        dev;
        struct mtx      sc_mtx;
        struct resource *mem_res;
};

static struct zy7_slcr_softc *zy7_slcr_softc_p;
extern void (*zynq7_cpu_reset);

#define ZSLCR_LOCK(sc)          mtx_lock(&(sc)->sc_mtx)
#define ZSLCR_UNLOCK(sc)                mtx_unlock(&(sc)->sc_mtx)
#define ZSLCR_LOCK_INIT(sc) \
        mtx_init(&(sc)->sc_mtx, device_get_nameunit((sc)->dev), \
            "zy7_slcr", MTX_DEF)
#define ZSLCR_LOCK_DESTROY(_sc) mtx_destroy(&_sc->sc_mtx);

#define RD4(sc, off)            (bus_read_4((sc)->mem_res, (off)))
#define WR4(sc, off, val)       (bus_write_4((sc)->mem_res, (off), (val)))

#define ZYNQ_DEFAULT_PS_CLK_FREQUENCY   33333333        /* 33.3 Mhz */

SYSCTL_NODE(_hw, OID_AUTO, zynq, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
    "Xilinx Zynq-7000");

static char zynq_bootmode[64];
SYSCTL_STRING(_hw_zynq, OID_AUTO, bootmode, CTLFLAG_RD, zynq_bootmode, 0,
              "Zynq boot mode");

static char zynq_pssid[100];
SYSCTL_STRING(_hw_zynq, OID_AUTO, pssid, CTLFLAG_RD, zynq_pssid, 0,
           "Zynq PSS IDCODE");

static uint32_t zynq_reboot_status;
SYSCTL_INT(_hw_zynq, OID_AUTO, reboot_status, CTLFLAG_RD, &zynq_reboot_status,
           0, "Zynq REBOOT_STATUS register");

static int ps_clk_frequency;
SYSCTL_INT(_hw_zynq, OID_AUTO, ps_clk_frequency, CTLFLAG_RD, &ps_clk_frequency,
           0, "Zynq PS_CLK Frequency");

static int io_pll_frequency;
SYSCTL_INT(_hw_zynq, OID_AUTO, io_pll_frequency, CTLFLAG_RD, &io_pll_frequency,
           0, "Zynq IO PLL Frequency");

static int arm_pll_frequency;
SYSCTL_INT(_hw_zynq, OID_AUTO, arm_pll_frequency, CTLFLAG_RD,
           &arm_pll_frequency, 0, "Zynq ARM PLL Frequency");

static int ddr_pll_frequency;
SYSCTL_INT(_hw_zynq, OID_AUTO, ddr_pll_frequency, CTLFLAG_RD,
           &ddr_pll_frequency, 0, "Zynq DDR PLL Frequency");

static void
zy7_slcr_unlock(struct zy7_slcr_softc *sc)
{

        /* Unlock SLCR with magic number. */
        WR4(sc, ZY7_SLCR_UNLOCK, ZY7_SLCR_UNLOCK_MAGIC);
}

static void
zy7_slcr_lock(struct zy7_slcr_softc *sc)
{

        /* Lock SLCR with magic number. */
        WR4(sc, ZY7_SLCR_LOCK, ZY7_SLCR_LOCK_MAGIC);
}

static void
zy7_slcr_cpu_reset(void)
{
        struct zy7_slcr_softc *sc = zy7_slcr_softc_p;

        /* Unlock SLCR registers. */
        zy7_slcr_unlock(sc);

        /* This has something to do with a work-around so the fsbl will load
         * the bitstream after soft-reboot.  It's very important.
         */
        WR4(sc, ZY7_SLCR_REBOOT_STAT,
            RD4(sc, ZY7_SLCR_REBOOT_STAT) & 0xf0ffffff);

        /* Soft reset */
        WR4(sc, ZY7_SLCR_PSS_RST_CTRL, ZY7_SLCR_PSS_RST_CTRL_SOFT_RESET);

        for (;;)
                ;
}

/* Assert PL resets and disable level shifters in preparation of programming
 * the PL (FPGA) section.  Called from zy7_devcfg.c.
 */
void
zy7_slcr_preload_pl(void)
{
        struct zy7_slcr_softc *sc = zy7_slcr_softc_p;

        if (!sc)
                return;

        ZSLCR_LOCK(sc);

        /* Unlock SLCR registers. */
        zy7_slcr_unlock(sc);

        /* Assert top level output resets. */
        WR4(sc, ZY7_SLCR_FPGA_RST_CTRL, ZY7_SLCR_FPGA_RST_CTRL_RST_ALL);

        /* Disable all level shifters. */
        WR4(sc, ZY7_SLCR_LVL_SHFTR_EN, 0);

        /* Lock SLCR registers. */
        zy7_slcr_lock(sc);

        ZSLCR_UNLOCK(sc);
}

/* After PL configuration, enable level shifters and deassert top-level
 * PL resets.  Called from zy7_devcfg.c.  Optionally, the level shifters
 * can be left disabled but that's rare of an FPGA application. That option
 * is controlled by a sysctl in the devcfg driver.
 */
void
zy7_slcr_postload_pl(int en_level_shifters)
{
        struct zy7_slcr_softc *sc = zy7_slcr_softc_p;

        if (!sc)
                return;

        ZSLCR_LOCK(sc);

        /* Unlock SLCR registers. */
        zy7_slcr_unlock(sc);

        if (en_level_shifters)
                /* Enable level shifters. */
                WR4(sc, ZY7_SLCR_LVL_SHFTR_EN, ZY7_SLCR_LVL_SHFTR_EN_ALL);

        /* Deassert top level output resets. */
        WR4(sc, ZY7_SLCR_FPGA_RST_CTRL, 0);

        /* Lock SLCR registers. */
        zy7_slcr_lock(sc);

        ZSLCR_UNLOCK(sc);
}

/* Override cgem_set_refclk() in gigabit ethernet driver
 * (sys/dev/cadence/if_cgem.c).  This function is called to
 * request a change in the gem's reference clock speed.
 */
int
cgem_set_ref_clk(int unit, int frequency)
{
        struct zy7_slcr_softc *sc = zy7_slcr_softc_p;
        int div0, div1;

        if (!sc)
                return (-1);

        /* Find suitable divisor pairs.  Round result to nearest khz
         * to test for match.
         */
        for (div1 = 1; div1 <= ZY7_SLCR_GEM_CLK_CTRL_DIVISOR1_MAX; div1++) {
                div0 = (io_pll_frequency + div1 * frequency / 2) /
                        div1 / frequency;
                if (div0 > 0 && div0 <= ZY7_SLCR_GEM_CLK_CTRL_DIVISOR_MAX &&
                    ((io_pll_frequency / div0 / div1) + 500) / 1000 ==
                    (frequency + 500) / 1000)
                        break;
        }

        if (div1 > ZY7_SLCR_GEM_CLK_CTRL_DIVISOR1_MAX)
                return (-1);

        ZSLCR_LOCK(sc);

        /* Unlock SLCR registers. */
        zy7_slcr_unlock(sc);

        /* Modify GEM reference clock. */
        WR4(sc, unit ? ZY7_SLCR_GEM1_CLK_CTRL : ZY7_SLCR_GEM0_CLK_CTRL,
            (div1 << ZY7_SLCR_GEM_CLK_CTRL_DIVISOR1_SHIFT) |
            (div0 << ZY7_SLCR_GEM_CLK_CTRL_DIVISOR_SHIFT) |
            ZY7_SLCR_GEM_CLK_CTRL_SRCSEL_IO_PLL |
            ZY7_SLCR_GEM_CLK_CTRL_CLKACT);

        /* Lock SLCR registers. */
        zy7_slcr_lock(sc);

        ZSLCR_UNLOCK(sc);

        return (0);
}

/* 
 * PL clocks management function
 */
int 
zy7_pl_fclk_set_source(int unit, int source)
{
        struct zy7_slcr_softc *sc = zy7_slcr_softc_p;
        uint32_t reg;

        if (!sc)
                return (-1);

        ZSLCR_LOCK(sc);

        /* Unlock SLCR registers. */
        zy7_slcr_unlock(sc);

        /* Modify FPGAx source. */
        reg = RD4(sc, ZY7_SLCR_FPGA_CLK_CTRL(unit));
        reg &= ~(ZY7_SLCR_FPGA_CLK_CTRL_SRCSEL_MASK);
        reg |= (source << ZY7_SLCR_FPGA_CLK_CTRL_SRCSEL_SHIFT);
        WR4(sc, ZY7_SLCR_FPGA_CLK_CTRL(unit), reg);

        /* Lock SLCR registers. */
        zy7_slcr_lock(sc);

        ZSLCR_UNLOCK(sc);

        return (0);
}

int 
zy7_pl_fclk_get_source(int unit)
{
        struct zy7_slcr_softc *sc = zy7_slcr_softc_p;
        uint32_t reg;
        int source;

        if (!sc)
                return (-1);

        ZSLCR_LOCK(sc);

        /* Modify GEM reference clock. */
        reg = RD4(sc, ZY7_SLCR_FPGA_CLK_CTRL(unit));
        source = (reg & ZY7_SLCR_FPGA_CLK_CTRL_SRCSEL_MASK) >> 
            ZY7_SLCR_FPGA_CLK_CTRL_SRCSEL_SHIFT;

        /* ZY7_PL_FCLK_SRC_IO is actually b0x */
        if ((source & 2) == 0)
                source = ZY7_PL_FCLK_SRC_IO;

        ZSLCR_UNLOCK(sc);

        return (source);
}

int
zy7_pl_fclk_set_freq(int unit, int frequency)
{
        struct zy7_slcr_softc *sc = zy7_slcr_softc_p;
        int div0, div1;
        int base_frequency;
        uint32_t reg;
        int source;

        if (!sc)
                return (-1);

        source = zy7_pl_fclk_get_source(unit);
        switch (source) {
                case ZY7_PL_FCLK_SRC_IO:
                        base_frequency = io_pll_frequency;
                        break;

                case ZY7_PL_FCLK_SRC_ARM:
                        base_frequency = arm_pll_frequency;
                        break;

                case ZY7_PL_FCLK_SRC_DDR:
                        base_frequency = ddr_pll_frequency;
                        break;

                default:
                        return (-1);
        }

        /* Find suitable divisor pairs.  Round result to nearest khz
         * to test for match.
         */
        for (div1 = 1; div1 <= ZY7_SLCR_FPGA_CLK_CTRL_DIVISOR_MAX; div1++) {
                div0 = (base_frequency + div1 * frequency / 2) /
                        div1 / frequency;
                if (div0 > 0 && div0 <= ZY7_SLCR_FPGA_CLK_CTRL_DIVISOR_MAX &&
                    ((base_frequency / div0 / div1) + 500) / 1000 ==
                    (frequency + 500) / 1000)
                        break;
        }

        if (div1 > ZY7_SLCR_FPGA_CLK_CTRL_DIVISOR_MAX)
                return (-1);

        ZSLCR_LOCK(sc);

        /* Unlock SLCR registers. */
        zy7_slcr_unlock(sc);

        /* Modify FPGAx reference clock. */
        reg = RD4(sc, ZY7_SLCR_FPGA_CLK_CTRL(unit));
        reg &= ~(ZY7_SLCR_FPGA_CLK_CTRL_DIVISOR1_MASK |
            ZY7_SLCR_FPGA_CLK_CTRL_DIVISOR0_MASK);
        reg |= (div1 << ZY7_SLCR_FPGA_CLK_CTRL_DIVISOR1_SHIFT) |
            (div0 << ZY7_SLCR_FPGA_CLK_CTRL_DIVISOR0_SHIFT);
        WR4(sc, ZY7_SLCR_FPGA_CLK_CTRL(unit), reg);

        /* Lock SLCR registers. */
        zy7_slcr_lock(sc);

        ZSLCR_UNLOCK(sc);

        return (base_frequency / div0 / div1);
}

int
zy7_pl_fclk_get_freq(int unit)
{
        struct zy7_slcr_softc *sc = zy7_slcr_softc_p;
        int div0, div1;
        int base_frequency;
        int frequency;
        uint32_t reg;
        int source;

        if (!sc)
                return (-1);

        source = zy7_pl_fclk_get_source(unit);
        switch (source) {
                case ZY7_PL_FCLK_SRC_IO:
                        base_frequency = io_pll_frequency;
                        break;

                case ZY7_PL_FCLK_SRC_ARM:
                        base_frequency = arm_pll_frequency;
                        break;

                case ZY7_PL_FCLK_SRC_DDR:
                        base_frequency = ddr_pll_frequency;
                        break;

                default:
                        return (-1);
        }

        ZSLCR_LOCK(sc);

        /* Modify FPGAx reference clock. */
        reg = RD4(sc, ZY7_SLCR_FPGA_CLK_CTRL(unit));
        div1 = (reg & ZY7_SLCR_FPGA_CLK_CTRL_DIVISOR1_MASK) >>
            ZY7_SLCR_FPGA_CLK_CTRL_DIVISOR1_SHIFT;
        div0 = (reg & ZY7_SLCR_FPGA_CLK_CTRL_DIVISOR0_MASK) >>
            ZY7_SLCR_FPGA_CLK_CTRL_DIVISOR0_SHIFT;

        ZSLCR_UNLOCK(sc);

        if (div0 == 0)
                div0 = 1;

        if (div1 == 0)
                div1 = 1;

        frequency = (base_frequency / div0 / div1);
        /* Round to KHz */
        frequency = (frequency + 500) / 1000;
        frequency = frequency * 1000;

        return (frequency);
}

int 
zy7_pl_fclk_enable(int unit)
{
        struct zy7_slcr_softc *sc = zy7_slcr_softc_p;

        if (!sc)
                return (-1);

        ZSLCR_LOCK(sc);

        /* Unlock SLCR registers. */
        zy7_slcr_unlock(sc);

        WR4(sc, ZY7_SLCR_FPGA_THR_CTRL(unit), 0);
        WR4(sc, ZY7_SLCR_FPGA_THR_CNT(unit), 0);

        /* Lock SLCR registers. */
        zy7_slcr_lock(sc);

        ZSLCR_UNLOCK(sc);

        return (0);
}

int 
zy7_pl_fclk_disable(int unit)
{
        struct zy7_slcr_softc *sc = zy7_slcr_softc_p;

        if (!sc)
                return (-1);

        ZSLCR_LOCK(sc);

        /* Unlock SLCR registers. */
        zy7_slcr_unlock(sc);

        WR4(sc, ZY7_SLCR_FPGA_THR_CTRL(unit), 0);
        WR4(sc, ZY7_SLCR_FPGA_THR_CNT(unit), 1);

        /* Lock SLCR registers. */
        zy7_slcr_lock(sc);

        ZSLCR_UNLOCK(sc);

        return (0);
}

int 
zy7_pl_fclk_enabled(int unit)
{
        struct zy7_slcr_softc *sc = zy7_slcr_softc_p;
        uint32_t reg;

        if (!sc)
                return (-1);

        ZSLCR_LOCK(sc);
        reg = RD4(sc, ZY7_SLCR_FPGA_THR_CNT(unit));
        ZSLCR_UNLOCK(sc);

        return !(reg & 1);
}

int
zy7_pl_level_shifters_enabled(void)
{
        struct zy7_slcr_softc *sc = zy7_slcr_softc_p;

        uint32_t reg;

        if (!sc)
                return (-1);

        ZSLCR_LOCK(sc);
        reg = RD4(sc, ZY7_SLCR_LVL_SHFTR_EN);
        ZSLCR_UNLOCK(sc);

        return (reg == ZY7_SLCR_LVL_SHFTR_EN_ALL);
}

void
zy7_pl_level_shifters_enable(void)
{
        struct zy7_slcr_softc *sc = zy7_slcr_softc_p;

        if (!sc)
                return;

        ZSLCR_LOCK(sc);
        zy7_slcr_unlock(sc);
        WR4(sc, ZY7_SLCR_LVL_SHFTR_EN, ZY7_SLCR_LVL_SHFTR_EN_ALL);
        zy7_slcr_lock(sc);
        ZSLCR_UNLOCK(sc);
}

void
zy7_pl_level_shifters_disable(void)
{
        struct zy7_slcr_softc *sc = zy7_slcr_softc_p;

        if (!sc)
                return;

        ZSLCR_LOCK(sc);
        zy7_slcr_unlock(sc);
        WR4(sc, ZY7_SLCR_LVL_SHFTR_EN, 0);
        zy7_slcr_lock(sc);
        ZSLCR_UNLOCK(sc);
}

static int
zy7_slcr_probe(device_t dev)
{

        if (!ofw_bus_status_okay(dev))
                return (ENXIO);

        if (!ofw_bus_is_compatible(dev, "xlnx,zy7_slcr"))
                return (ENXIO);

        device_set_desc(dev, "Zynq-7000 slcr block");
        return (0);
}

static int
zy7_slcr_attach(device_t dev)
{
        struct zy7_slcr_softc *sc = device_get_softc(dev);
        int rid;
        phandle_t node;
        pcell_t cell;
        uint32_t bootmode;
        uint32_t pss_idcode;
        uint32_t arm_pll_ctrl;
        uint32_t ddr_pll_ctrl;
        uint32_t io_pll_ctrl;
        static char *bootdev_names[] = {
                "JTAG", "Quad-SPI", "NOR", "(3?)",
                "NAND", "SD Card", "(6?)", "(7?)"
        };

        /* Allow only one attach. */
        if (zy7_slcr_softc_p != NULL)
                return (ENXIO);

        sc->dev = dev;

        ZSLCR_LOCK_INIT(sc);

        /* Get memory resource. */
        rid = 0;
        sc->mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid,
                                             RF_ACTIVE);
        if (sc->mem_res == NULL) {
                device_printf(dev, "could not allocate memory resources.\n");
                return (ENOMEM);
        }

        /* Hook up cpu_reset. */
        zy7_slcr_softc_p = sc;
        zynq7_cpu_reset = zy7_slcr_cpu_reset;

        /* Read info and set sysctls. */
        bootmode = RD4(sc, ZY7_SLCR_BOOT_MODE);
        snprintf(zynq_bootmode, sizeof(zynq_bootmode),
                 "0x%x: boot device: %s", bootmode,
                 bootdev_names[bootmode & ZY7_SLCR_BOOT_MODE_BOOTDEV_MASK]);

        pss_idcode = RD4(sc, ZY7_SLCR_PSS_IDCODE);
        snprintf(zynq_pssid, sizeof(zynq_pssid),
                 "0x%x: manufacturer: 0x%x device: 0x%x "
                 "family: 0x%x sub-family: 0x%x rev: 0x%x",
                 pss_idcode,
                 (pss_idcode & ZY7_SLCR_PSS_IDCODE_MNFR_ID_MASK) >>
                 ZY7_SLCR_PSS_IDCODE_MNFR_ID_SHIFT,
                 (pss_idcode & ZY7_SLCR_PSS_IDCODE_DEVICE_MASK) >>
                 ZY7_SLCR_PSS_IDCODE_DEVICE_SHIFT,
                 (pss_idcode & ZY7_SLCR_PSS_IDCODE_FAMILY_MASK) >>
                 ZY7_SLCR_PSS_IDCODE_FAMILY_SHIFT,
                 (pss_idcode & ZY7_SLCR_PSS_IDCODE_SUB_FAMILY_MASK) >>
                 ZY7_SLCR_PSS_IDCODE_SUB_FAMILY_SHIFT,
                 (pss_idcode & ZY7_SLCR_PSS_IDCODE_REVISION_MASK) >>
                 ZY7_SLCR_PSS_IDCODE_REVISION_SHIFT);

        zynq_reboot_status = RD4(sc, ZY7_SLCR_REBOOT_STAT);

        /* Derive PLL frequencies from PS_CLK. */
        node = ofw_bus_get_node(dev);
        if (OF_getencprop(node, "clock-frequency", &cell, sizeof(cell)) > 0)
                ps_clk_frequency = cell;
        else
                ps_clk_frequency = ZYNQ_DEFAULT_PS_CLK_FREQUENCY;

        arm_pll_ctrl = RD4(sc, ZY7_SLCR_ARM_PLL_CTRL);
        ddr_pll_ctrl = RD4(sc, ZY7_SLCR_DDR_PLL_CTRL);
        io_pll_ctrl = RD4(sc, ZY7_SLCR_IO_PLL_CTRL);

        /* Determine ARM PLL frequency. */
        if (((arm_pll_ctrl & ZY7_SLCR_PLL_CTRL_BYPASS_QUAL) == 0 &&
             (arm_pll_ctrl & ZY7_SLCR_PLL_CTRL_BYPASS_FORCE) != 0) ||
            ((arm_pll_ctrl & ZY7_SLCR_PLL_CTRL_BYPASS_QUAL) != 0 &&
             (bootmode & ZY7_SLCR_BOOT_MODE_PLL_BYPASS) != 0))
                /* PLL is bypassed. */
                arm_pll_frequency = ps_clk_frequency;
        else
                arm_pll_frequency = ps_clk_frequency *
                        ((arm_pll_ctrl & ZY7_SLCR_PLL_CTRL_FDIV_MASK) >>
                         ZY7_SLCR_PLL_CTRL_FDIV_SHIFT);

        /* Determine DDR PLL frequency. */
        if (((ddr_pll_ctrl & ZY7_SLCR_PLL_CTRL_BYPASS_QUAL) == 0 &&
             (ddr_pll_ctrl & ZY7_SLCR_PLL_CTRL_BYPASS_FORCE) != 0) ||
            ((ddr_pll_ctrl & ZY7_SLCR_PLL_CTRL_BYPASS_QUAL) != 0 &&
             (bootmode & ZY7_SLCR_BOOT_MODE_PLL_BYPASS) != 0))
                /* PLL is bypassed. */
                ddr_pll_frequency = ps_clk_frequency;
        else
                ddr_pll_frequency = ps_clk_frequency *
                        ((ddr_pll_ctrl & ZY7_SLCR_PLL_CTRL_FDIV_MASK) >>
                         ZY7_SLCR_PLL_CTRL_FDIV_SHIFT);

        /* Determine IO PLL frequency. */
        if (((io_pll_ctrl & ZY7_SLCR_PLL_CTRL_BYPASS_QUAL) == 0 &&
             (io_pll_ctrl & ZY7_SLCR_PLL_CTRL_BYPASS_FORCE) != 0) ||
            ((io_pll_ctrl & ZY7_SLCR_PLL_CTRL_BYPASS_QUAL) != 0 &&
             (bootmode & ZY7_SLCR_BOOT_MODE_PLL_BYPASS) != 0))
                /* PLL is bypassed. */
                io_pll_frequency = ps_clk_frequency;
        else
                io_pll_frequency = ps_clk_frequency *
                        ((io_pll_ctrl & ZY7_SLCR_PLL_CTRL_FDIV_MASK) >>
                         ZY7_SLCR_PLL_CTRL_FDIV_SHIFT);

        /* Lock SLCR registers. */
        zy7_slcr_lock(sc);

        return (0);
}

static int
zy7_slcr_detach(device_t dev)
{
        struct zy7_slcr_softc *sc = device_get_softc(dev);
        int error;

        error = bus_generic_detach(dev);
        if (error != 0)
                return (error);

        /* Release memory resource. */
        if (sc->mem_res != NULL)
                bus_release_resource(dev, SYS_RES_MEMORY,
                             rman_get_rid(sc->mem_res), sc->mem_res);

        zy7_slcr_softc_p = NULL;
        zynq7_cpu_reset = NULL;

        ZSLCR_LOCK_DESTROY(sc);

        return (0);
}

static device_method_t zy7_slcr_methods[] = {
        /* device_if */
        DEVMETHOD(device_probe,         zy7_slcr_probe),
        DEVMETHOD(device_attach,        zy7_slcr_attach),
        DEVMETHOD(device_detach,        zy7_slcr_detach),

        DEVMETHOD_END
};

static driver_t zy7_slcr_driver = {
        "zy7_slcr",
        zy7_slcr_methods,
        sizeof(struct zy7_slcr_softc),
};

DRIVER_MODULE(zy7_slcr, simplebus, zy7_slcr_driver, 0, 0);
MODULE_VERSION(zy7_slcr, 1);