of: MSI: Simplify irqdomain lookup

[linux/fpc-iii.git] / arch / arm / mach-mvebu / pmsu.c

/*
 * Power Management Service Unit(PMSU) support for Armada 370/XP platforms.
 *
 * Copyright (C) 2012 Marvell
 *
 * Yehuda Yitschak <yehuday@marvell.com>
 * Gregory Clement <gregory.clement@free-electrons.com>
 * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2.  This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 *
 * The Armada 370 and Armada XP SOCs have a power management service
 * unit which is responsible for powering down and waking up CPUs and
 * other SOC units
 */

#define pr_fmt(fmt) "mvebu-pmsu: " fmt

#include <linux/clk.h>
#include <linux/cpu_pm.h>
#include <linux/cpufreq-dt.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/mbus.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/pm_opp.h>
#include <linux/resource.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <asm/cacheflush.h>
#include <asm/cp15.h>
#include <asm/smp_scu.h>
#include <asm/smp_plat.h>
#include <asm/suspend.h>
#include <asm/tlbflush.h>
#include "common.h"


#define PMSU_BASE_OFFSET    0x100
#define PMSU_REG_SIZE       0x1000

/* PMSU MP registers */
#define PMSU_CONTROL_AND_CONFIG(cpu)        ((cpu * 0x100) + 0x104)
#define PMSU_CONTROL_AND_CONFIG_DFS_REQ         BIT(18)
#define PMSU_CONTROL_AND_CONFIG_PWDDN_REQ       BIT(16)
#define PMSU_CONTROL_AND_CONFIG_L2_PWDDN        BIT(20)

#define PMSU_CPU_POWER_DOWN_CONTROL(cpu)    ((cpu * 0x100) + 0x108)

#define PMSU_CPU_POWER_DOWN_DIS_SNP_Q_SKIP      BIT(0)

#define PMSU_STATUS_AND_MASK(cpu)           ((cpu * 0x100) + 0x10c)
#define PMSU_STATUS_AND_MASK_CPU_IDLE_WAIT      BIT(16)
#define PMSU_STATUS_AND_MASK_SNP_Q_EMPTY_WAIT   BIT(17)
#define PMSU_STATUS_AND_MASK_IRQ_WAKEUP         BIT(20)
#define PMSU_STATUS_AND_MASK_FIQ_WAKEUP         BIT(21)
#define PMSU_STATUS_AND_MASK_DBG_WAKEUP         BIT(22)
#define PMSU_STATUS_AND_MASK_IRQ_MASK           BIT(24)
#define PMSU_STATUS_AND_MASK_FIQ_MASK           BIT(25)

#define PMSU_EVENT_STATUS_AND_MASK(cpu)     ((cpu * 0x100) + 0x120)
#define PMSU_EVENT_STATUS_AND_MASK_DFS_DONE        BIT(1)
#define PMSU_EVENT_STATUS_AND_MASK_DFS_DONE_MASK   BIT(17)

#define PMSU_BOOT_ADDR_REDIRECT_OFFSET(cpu) ((cpu * 0x100) + 0x124)

/* PMSU fabric registers */
#define L2C_NFABRIC_PM_CTL                  0x4
#define L2C_NFABRIC_PM_CTL_PWR_DOWN             BIT(20)

/* PMSU delay registers */
#define PMSU_POWERDOWN_DELAY                0xF04
#define PMSU_POWERDOWN_DELAY_PMU                BIT(1)
#define PMSU_POWERDOWN_DELAY_MASK               0xFFFE
#define PMSU_DFLT_ARMADA38X_DELAY               0x64

/* CA9 MPcore SoC Control registers */

#define MPCORE_RESET_CTL                    0x64
#define MPCORE_RESET_CTL_L2                     BIT(0)
#define MPCORE_RESET_CTL_DEBUG                  BIT(16)

#define SRAM_PHYS_BASE  0xFFFF0000
#define BOOTROM_BASE    0xFFF00000
#define BOOTROM_SIZE    0x100000

#define ARMADA_370_CRYPT0_ENG_TARGET   0x9
#define ARMADA_370_CRYPT0_ENG_ATTR     0x1

extern void ll_disable_coherency(void);
extern void ll_enable_coherency(void);

extern void armada_370_xp_cpu_resume(void);
extern void armada_38x_cpu_resume(void);

static phys_addr_t pmsu_mp_phys_base;
static void __iomem *pmsu_mp_base;

static void *mvebu_cpu_resume;

static const struct of_device_id of_pmsu_table[] = {
        { .compatible = "marvell,armada-370-pmsu", },
        { .compatible = "marvell,armada-370-xp-pmsu", },
        { .compatible = "marvell,armada-380-pmsu", },
        { /* end of list */ },
};

void mvebu_pmsu_set_cpu_boot_addr(int hw_cpu, void *boot_addr)
{
        writel(virt_to_phys(boot_addr), pmsu_mp_base +
                PMSU_BOOT_ADDR_REDIRECT_OFFSET(hw_cpu));
}

extern unsigned char mvebu_boot_wa_start;
extern unsigned char mvebu_boot_wa_end;

/*
 * This function sets up the boot address workaround needed for SMP
 * boot on Armada 375 Z1 and cpuidle on Armada 370. It unmaps the
 * BootROM Mbus window, and instead remaps a crypto SRAM into which a
 * custom piece of code is copied to replace the problematic BootROM.
 */
int mvebu_setup_boot_addr_wa(unsigned int crypto_eng_target,
                             unsigned int crypto_eng_attribute,
                             phys_addr_t resume_addr_reg)
{
        void __iomem *sram_virt_base;
        u32 code_len = &mvebu_boot_wa_end - &mvebu_boot_wa_start;

        mvebu_mbus_del_window(BOOTROM_BASE, BOOTROM_SIZE);
        mvebu_mbus_add_window_by_id(crypto_eng_target, crypto_eng_attribute,
                                    SRAM_PHYS_BASE, SZ_64K);

        sram_virt_base = ioremap(SRAM_PHYS_BASE, SZ_64K);
        if (!sram_virt_base) {
                pr_err("Unable to map SRAM to setup the boot address WA\n");
                return -ENOMEM;
        }

        memcpy(sram_virt_base, &mvebu_boot_wa_start, code_len);

        /*
         * The last word of the code copied in SRAM must contain the
         * physical base address of the PMSU register. We
         * intentionally store this address in the native endianness
         * of the system.
         */
        __raw_writel((unsigned long)resume_addr_reg,
                     sram_virt_base + code_len - 4);

        iounmap(sram_virt_base);

        return 0;
}

static int __init mvebu_v7_pmsu_init(void)
{
        struct device_node *np;
        struct resource res;
        int ret = 0;

        np = of_find_matching_node(NULL, of_pmsu_table);
        if (!np)
                return 0;

        pr_info("Initializing Power Management Service Unit\n");

        if (of_address_to_resource(np, 0, &res)) {
                pr_err("unable to get resource\n");
                ret = -ENOENT;
                goto out;
        }

        if (of_device_is_compatible(np, "marvell,armada-370-xp-pmsu")) {
                pr_warn(FW_WARN "deprecated pmsu binding\n");
                res.start = res.start - PMSU_BASE_OFFSET;
                res.end = res.start + PMSU_REG_SIZE - 1;
        }

        if (!request_mem_region(res.start, resource_size(&res),
                                np->full_name)) {
                pr_err("unable to request region\n");
                ret = -EBUSY;
                goto out;
        }

        pmsu_mp_phys_base = res.start;

        pmsu_mp_base = ioremap(res.start, resource_size(&res));
        if (!pmsu_mp_base) {
                pr_err("unable to map registers\n");
                release_mem_region(res.start, resource_size(&res));
                ret = -ENOMEM;
                goto out;
        }

 out:
        of_node_put(np);
        return ret;
}

static void mvebu_v7_pmsu_enable_l2_powerdown_onidle(void)
{
        u32 reg;

        if (pmsu_mp_base == NULL)
                return;

        /* Enable L2 & Fabric powerdown in Deep-Idle mode - Fabric */
        reg = readl(pmsu_mp_base + L2C_NFABRIC_PM_CTL);
        reg |= L2C_NFABRIC_PM_CTL_PWR_DOWN;
        writel(reg, pmsu_mp_base + L2C_NFABRIC_PM_CTL);
}

enum pmsu_idle_prepare_flags {
        PMSU_PREPARE_NORMAL = 0,
        PMSU_PREPARE_DEEP_IDLE = BIT(0),
        PMSU_PREPARE_SNOOP_DISABLE = BIT(1),
};

/* No locking is needed because we only access per-CPU registers */
static int mvebu_v7_pmsu_idle_prepare(unsigned long flags)
{
        unsigned int hw_cpu = cpu_logical_map(smp_processor_id());
        u32 reg;

        if (pmsu_mp_base == NULL)
                return -EINVAL;

        /*
         * Adjust the PMSU configuration to wait for WFI signal, enable
         * IRQ and FIQ as wakeup events, set wait for snoop queue empty
         * indication and mask IRQ and FIQ from CPU
         */
        reg = readl(pmsu_mp_base + PMSU_STATUS_AND_MASK(hw_cpu));
        reg |= PMSU_STATUS_AND_MASK_CPU_IDLE_WAIT    |
               PMSU_STATUS_AND_MASK_IRQ_WAKEUP       |
               PMSU_STATUS_AND_MASK_FIQ_WAKEUP       |
               PMSU_STATUS_AND_MASK_SNP_Q_EMPTY_WAIT |
               PMSU_STATUS_AND_MASK_IRQ_MASK         |
               PMSU_STATUS_AND_MASK_FIQ_MASK;
        writel(reg, pmsu_mp_base + PMSU_STATUS_AND_MASK(hw_cpu));

        reg = readl(pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(hw_cpu));
        /* ask HW to power down the L2 Cache if needed */
        if (flags & PMSU_PREPARE_DEEP_IDLE)
                reg |= PMSU_CONTROL_AND_CONFIG_L2_PWDDN;

        /* request power down */
        reg |= PMSU_CONTROL_AND_CONFIG_PWDDN_REQ;
        writel(reg, pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(hw_cpu));

        if (flags & PMSU_PREPARE_SNOOP_DISABLE) {
                /* Disable snoop disable by HW - SW is taking care of it */
                reg = readl(pmsu_mp_base + PMSU_CPU_POWER_DOWN_CONTROL(hw_cpu));
                reg |= PMSU_CPU_POWER_DOWN_DIS_SNP_Q_SKIP;
                writel(reg, pmsu_mp_base + PMSU_CPU_POWER_DOWN_CONTROL(hw_cpu));
        }

        return 0;
}

int armada_370_xp_pmsu_idle_enter(unsigned long deepidle)
{
        unsigned long flags = PMSU_PREPARE_SNOOP_DISABLE;
        int ret;

        if (deepidle)
                flags |= PMSU_PREPARE_DEEP_IDLE;

        ret = mvebu_v7_pmsu_idle_prepare(flags);
        if (ret)
                return ret;

        v7_exit_coherency_flush(all);

        ll_disable_coherency();

        dsb();

        wfi();

        /* If we are here, wfi failed. As processors run out of
         * coherency for some time, tlbs might be stale, so flush them
         */
        local_flush_tlb_all();

        ll_enable_coherency();

        /* Test the CR_C bit and set it if it was cleared */
        asm volatile(
        "mrc    p15, 0, r0, c1, c0, 0 \n\t"
        "tst    r0, %0 \n\t"
        "orreq  r0, r0, #(1 << 2) \n\t"
        "mcreq  p15, 0, r0, c1, c0, 0 \n\t"
        "isb    "
        : : "Ir" (CR_C) : "r0");

        pr_debug("Failed to suspend the system\n");

        return 0;
}

static int armada_370_xp_cpu_suspend(unsigned long deepidle)
{
        return cpu_suspend(deepidle, armada_370_xp_pmsu_idle_enter);
}

int armada_38x_do_cpu_suspend(unsigned long deepidle)
{
        unsigned long flags = 0;

        if (deepidle)
                flags |= PMSU_PREPARE_DEEP_IDLE;

        mvebu_v7_pmsu_idle_prepare(flags);
        /*
         * Already flushed cache, but do it again as the outer cache
         * functions dirty the cache with spinlocks
         */
        v7_exit_coherency_flush(louis);

        scu_power_mode(mvebu_get_scu_base(), SCU_PM_POWEROFF);

        cpu_do_idle();

        return 1;
}

static int armada_38x_cpu_suspend(unsigned long deepidle)
{
        return cpu_suspend(false, armada_38x_do_cpu_suspend);
}

/* No locking is needed because we only access per-CPU registers */
void mvebu_v7_pmsu_idle_exit(void)
{
        unsigned int hw_cpu = cpu_logical_map(smp_processor_id());
        u32 reg;

        if (pmsu_mp_base == NULL)
                return;
        /* cancel ask HW to power down the L2 Cache if possible */
        reg = readl(pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(hw_cpu));
        reg &= ~PMSU_CONTROL_AND_CONFIG_L2_PWDDN;
        writel(reg, pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(hw_cpu));

        /* cancel Enable wakeup events and mask interrupts */
        reg = readl(pmsu_mp_base + PMSU_STATUS_AND_MASK(hw_cpu));
        reg &= ~(PMSU_STATUS_AND_MASK_IRQ_WAKEUP | PMSU_STATUS_AND_MASK_FIQ_WAKEUP);
        reg &= ~PMSU_STATUS_AND_MASK_CPU_IDLE_WAIT;
        reg &= ~PMSU_STATUS_AND_MASK_SNP_Q_EMPTY_WAIT;
        reg &= ~(PMSU_STATUS_AND_MASK_IRQ_MASK | PMSU_STATUS_AND_MASK_FIQ_MASK);
        writel(reg, pmsu_mp_base + PMSU_STATUS_AND_MASK(hw_cpu));
}

static int mvebu_v7_cpu_pm_notify(struct notifier_block *self,
                                    unsigned long action, void *hcpu)
{
        if (action == CPU_PM_ENTER) {
                unsigned int hw_cpu = cpu_logical_map(smp_processor_id());
                mvebu_pmsu_set_cpu_boot_addr(hw_cpu, mvebu_cpu_resume);
        } else if (action == CPU_PM_EXIT) {
                mvebu_v7_pmsu_idle_exit();
        }

        return NOTIFY_OK;
}

static struct notifier_block mvebu_v7_cpu_pm_notifier = {
        .notifier_call = mvebu_v7_cpu_pm_notify,
};

static struct platform_device mvebu_v7_cpuidle_device;

static int broken_idle(struct device_node *np)
{
        if (of_property_read_bool(np, "broken-idle")) {
                pr_warn("CPU idle is currently broken: disabling\n");
                return 1;
        }

        return 0;
}

static __init int armada_370_cpuidle_init(void)
{
        struct device_node *np;
        phys_addr_t redirect_reg;

        np = of_find_compatible_node(NULL, NULL, "marvell,coherency-fabric");
        if (!np)
                return -ENODEV;

        if (broken_idle(np))
                goto end;

        /*
         * On Armada 370, there is "a slow exit process from the deep
         * idle state due to heavy L1/L2 cache cleanup operations
         * performed by the BootROM software". To avoid this, we
         * replace the restart code of the bootrom by a a simple jump
         * to the boot address. Then the code located at this boot
         * address will take care of the initialization.
         */
        redirect_reg = pmsu_mp_phys_base + PMSU_BOOT_ADDR_REDIRECT_OFFSET(0);
        mvebu_setup_boot_addr_wa(ARMADA_370_CRYPT0_ENG_TARGET,
                                 ARMADA_370_CRYPT0_ENG_ATTR,
                                 redirect_reg);

        mvebu_cpu_resume = armada_370_xp_cpu_resume;
        mvebu_v7_cpuidle_device.dev.platform_data = armada_370_xp_cpu_suspend;
        mvebu_v7_cpuidle_device.name = "cpuidle-armada-370";

end:
        of_node_put(np);
        return 0;
}

static __init int armada_38x_cpuidle_init(void)
{
        struct device_node *np;
        void __iomem *mpsoc_base;
        u32 reg;

        pr_warn("CPU idle is currently broken on Armada 38x: disabling\n");
        return 0;

        np = of_find_compatible_node(NULL, NULL,
                                     "marvell,armada-380-coherency-fabric");
        if (!np)
                return -ENODEV;

        if (broken_idle(np))
                goto end;

        of_node_put(np);

        np = of_find_compatible_node(NULL, NULL,
                                     "marvell,armada-380-mpcore-soc-ctrl");
        if (!np)
                return -ENODEV;
        mpsoc_base = of_iomap(np, 0);
        BUG_ON(!mpsoc_base);

        /* Set up reset mask when powering down the cpus */
        reg = readl(mpsoc_base + MPCORE_RESET_CTL);
        reg |= MPCORE_RESET_CTL_L2;
        reg |= MPCORE_RESET_CTL_DEBUG;
        writel(reg, mpsoc_base + MPCORE_RESET_CTL);
        iounmap(mpsoc_base);

        /* Set up delay */
        reg = readl(pmsu_mp_base + PMSU_POWERDOWN_DELAY);
        reg &= ~PMSU_POWERDOWN_DELAY_MASK;
        reg |= PMSU_DFLT_ARMADA38X_DELAY;
        reg |= PMSU_POWERDOWN_DELAY_PMU;
        writel(reg, pmsu_mp_base + PMSU_POWERDOWN_DELAY);

        mvebu_cpu_resume = armada_38x_cpu_resume;
        mvebu_v7_cpuidle_device.dev.platform_data = armada_38x_cpu_suspend;
        mvebu_v7_cpuidle_device.name = "cpuidle-armada-38x";

end:
        of_node_put(np);
        return 0;
}

static __init int armada_xp_cpuidle_init(void)
{
        struct device_node *np;

        np = of_find_compatible_node(NULL, NULL, "marvell,coherency-fabric");
        if (!np)
                return -ENODEV;

        if (broken_idle(np))
                goto end;

        mvebu_cpu_resume = armada_370_xp_cpu_resume;
        mvebu_v7_cpuidle_device.dev.platform_data = armada_370_xp_cpu_suspend;
        mvebu_v7_cpuidle_device.name = "cpuidle-armada-xp";

end:
        of_node_put(np);
        return 0;
}

static int __init mvebu_v7_cpu_pm_init(void)
{
        struct device_node *np;
        int ret;

        np = of_find_matching_node(NULL, of_pmsu_table);
        if (!np)
                return 0;
        of_node_put(np);

        /*
         * Currently the CPU idle support for Armada 38x is broken, as
         * the CPU hotplug uses some of the CPU idle functions it is
         * broken too, so let's disable it
         */
        if (of_machine_is_compatible("marvell,armada380")) {
                cpu_hotplug_disable();
                pr_warn("CPU hotplug support is currently broken on Armada 38x: disabling\n");
        }

        if (of_machine_is_compatible("marvell,armadaxp"))
                ret = armada_xp_cpuidle_init();
        else if (of_machine_is_compatible("marvell,armada370"))
                ret = armada_370_cpuidle_init();
        else if (of_machine_is_compatible("marvell,armada380"))
                ret = armada_38x_cpuidle_init();
        else
                return 0;

        if (ret)
                return ret;

        mvebu_v7_pmsu_enable_l2_powerdown_onidle();
        if (mvebu_v7_cpuidle_device.name)
                platform_device_register(&mvebu_v7_cpuidle_device);
        cpu_pm_register_notifier(&mvebu_v7_cpu_pm_notifier);

        return 0;
}

arch_initcall(mvebu_v7_cpu_pm_init);
early_initcall(mvebu_v7_pmsu_init);

static void mvebu_pmsu_dfs_request_local(void *data)
{
        u32 reg;
        u32 cpu = smp_processor_id();
        unsigned long flags;

        local_irq_save(flags);

        /* Prepare to enter idle */
        reg = readl(pmsu_mp_base + PMSU_STATUS_AND_MASK(cpu));
        reg |= PMSU_STATUS_AND_MASK_CPU_IDLE_WAIT |
               PMSU_STATUS_AND_MASK_IRQ_MASK     |
               PMSU_STATUS_AND_MASK_FIQ_MASK;
        writel(reg, pmsu_mp_base + PMSU_STATUS_AND_MASK(cpu));

        /* Request the DFS transition */
        reg = readl(pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(cpu));
        reg |= PMSU_CONTROL_AND_CONFIG_DFS_REQ;
        writel(reg, pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(cpu));

        /* The fact of entering idle will trigger the DFS transition */
        wfi();

        /*
         * We're back from idle, the DFS transition has completed,
         * clear the idle wait indication.
         */
        reg = readl(pmsu_mp_base + PMSU_STATUS_AND_MASK(cpu));
        reg &= ~PMSU_STATUS_AND_MASK_CPU_IDLE_WAIT;
        writel(reg, pmsu_mp_base + PMSU_STATUS_AND_MASK(cpu));

        local_irq_restore(flags);
}

int mvebu_pmsu_dfs_request(int cpu)
{
        unsigned long timeout;
        int hwcpu = cpu_logical_map(cpu);
        u32 reg;

        /* Clear any previous DFS DONE event */
        reg = readl(pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
        reg &= ~PMSU_EVENT_STATUS_AND_MASK_DFS_DONE;
        writel(reg, pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));

        /* Mask the DFS done interrupt, since we are going to poll */
        reg = readl(pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
        reg |= PMSU_EVENT_STATUS_AND_MASK_DFS_DONE_MASK;
        writel(reg, pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));

        /* Trigger the DFS on the appropriate CPU */
        smp_call_function_single(cpu, mvebu_pmsu_dfs_request_local,
                                 NULL, false);

        /* Poll until the DFS done event is generated */
        timeout = jiffies + HZ;
        while (time_before(jiffies, timeout)) {
                reg = readl(pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
                if (reg & PMSU_EVENT_STATUS_AND_MASK_DFS_DONE)
                        break;
                udelay(10);
        }

        if (time_after(jiffies, timeout))
                return -ETIME;

        /* Restore the DFS mask to its original state */
        reg = readl(pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
        reg &= ~PMSU_EVENT_STATUS_AND_MASK_DFS_DONE_MASK;
        writel(reg, pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));

        return 0;
}

struct cpufreq_dt_platform_data cpufreq_dt_pd = {
        .independent_clocks = true,
};

static int __init armada_xp_pmsu_cpufreq_init(void)
{
        struct device_node *np;
        struct resource res;
        int ret, cpu;

        if (!of_machine_is_compatible("marvell,armadaxp"))
                return 0;

        /*
         * In order to have proper cpufreq handling, we need to ensure
         * that the Device Tree description of the CPU clock includes
         * the definition of the PMU DFS registers. If not, we do not
         * register the clock notifier and the cpufreq driver. This
         * piece of code is only for compatibility with old Device
         * Trees.
         */
        np = of_find_compatible_node(NULL, NULL, "marvell,armada-xp-cpu-clock");
        if (!np)
                return 0;

        ret = of_address_to_resource(np, 1, &res);
        if (ret) {
                pr_warn(FW_WARN "not enabling cpufreq, deprecated armada-xp-cpu-clock binding\n");
                of_node_put(np);
                return 0;
        }

        of_node_put(np);

        /*
         * For each CPU, this loop registers the operating points
         * supported (which are the nominal CPU frequency and half of
         * it), and registers the clock notifier that will take care
         * of doing the PMSU part of a frequency transition.
         */
        for_each_possible_cpu(cpu) {
                struct device *cpu_dev;
                struct clk *clk;
                int ret;

                cpu_dev = get_cpu_device(cpu);
                if (!cpu_dev) {
                        pr_err("Cannot get CPU %d\n", cpu);
                        continue;
                }

                clk = clk_get(cpu_dev, 0);
                if (IS_ERR(clk)) {
                        pr_err("Cannot get clock for CPU %d\n", cpu);
                        return PTR_ERR(clk);
                }

                /*
                 * In case of a failure of dev_pm_opp_add(), we don't
                 * bother with cleaning up the registered OPP (there's
                 * no function to do so), and simply cancel the
                 * registration of the cpufreq device.
                 */
                ret = dev_pm_opp_add(cpu_dev, clk_get_rate(clk), 0);
                if (ret) {
                        clk_put(clk);
                        return ret;
                }

                ret = dev_pm_opp_add(cpu_dev, clk_get_rate(clk) / 2, 0);
                if (ret) {
                        clk_put(clk);
                        return ret;
                }
        }

        platform_device_register_data(NULL, "cpufreq-dt", -1,
                                      &cpufreq_dt_pd, sizeof(cpufreq_dt_pd));
        return 0;
}

device_initcall(armada_xp_pmsu_cpufreq_init);