/*
 * Broadcom BCM63138 PMB initialization for secondary CPU(s)
 *
 * Copyright (C) 2015 Broadcom Corporation
 * Author: Florian Fainelli <f.fainelli@gmail.com>
 *
 * 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; either version 2 of the License, or
 * (at your option) any later version.
 */
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/spinlock.h>
#include <linux/reset/bcm63xx_pmb.h>
#include <linux/of.h>
#include <linux/of_address.h>

#include "bcm63xx_smp.h"

/* ARM Control register definitions */
#define CORE_PWR_CTRL_SHIFT     0
#define CORE_PWR_CTRL_MASK      0x3
#define PLL_PWR_ON              BIT(8)
#define PLL_LDO_PWR_ON          BIT(9)
#define PLL_CLAMP_ON            BIT(10)
#define CPU_RESET_N(x)          BIT(13 + (x))
#define NEON_RESET_N            BIT(15)
#define PWR_CTRL_STATUS_SHIFT   28
#define PWR_CTRL_STATUS_MASK    0x3
#define PWR_DOWN_SHIFT          30
#define PWR_DOWN_MASK           0x3

/* CPU Power control register definitions */
#define MEM_PWR_OK              BIT(0)
#define MEM_PWR_ON              BIT(1)
#define MEM_CLAMP_ON            BIT(2)
#define MEM_PWR_OK_STATUS       BIT(4)
#define MEM_PWR_ON_STATUS       BIT(5)
#define MEM_PDA_SHIFT           8
#define MEM_PDA_MASK            0xf
#define  MEM_PDA_CPU_MASK       0x1
#define  MEM_PDA_NEON_MASK      0xf
#define CLAMP_ON                BIT(15)
#define PWR_OK_SHIFT            16
#define PWR_OK_MASK             0xf
#define PWR_ON_SHIFT            20
#define  PWR_CPU_MASK           0x03
#define  PWR_NEON_MASK          0x01
#define PWR_ON_MASK             0xf
#define PWR_OK_STATUS_SHIFT     24
#define PWR_OK_STATUS_MASK      0xf
#define PWR_ON_STATUS_SHIFT     28
#define PWR_ON_STATUS_MASK      0xf

#define ARM_CONTROL             0x30
#define ARM_PWR_CONTROL_BASE    0x34
#define ARM_PWR_CONTROL(x)      (ARM_PWR_CONTROL_BASE + (x) * 0x4)
#define ARM_NEON_L2             0x3c

/* Perform a value write, then spin until the value shifted by
 * shift is seen, masked with mask and is different from cond.
 */
static int bpcm_wr_rd_mask(void __iomem *master,
                           unsigned int addr, u32 off, u32 *val,
                           u32 shift, u32 mask, u32 cond)
{
        int ret;

        ret = bpcm_wr(master, addr, off, *val);
        if (ret)
                return ret;

        do {
                ret = bpcm_rd(master, addr, off, val);
                if (ret)
                        return ret;

                cpu_relax();
        } while (((*val >> shift) & mask) != cond);

        return ret;
}

/* Global lock to serialize accesses to the PMB registers while we
 * are bringing up the secondary CPU
 */
static DEFINE_SPINLOCK(pmb_lock);

static int bcm63xx_pmb_get_resources(struct device_node *dn,
                                     void __iomem **base,
                                     unsigned int *cpu,
                                     unsigned int *addr)
{
        struct of_phandle_args args;
        int ret;

        ret = of_property_read_u32(dn, "reg", cpu);
        if (ret) {
                pr_err("CPU is missing a reg node\n");
                return ret;
        }

        ret = of_parse_phandle_with_args(dn, "resets", "#reset-cells",
                                         0, &args);
        if (ret) {
                pr_err("CPU is missing a resets phandle\n");
                return ret;
        }

        if (args.args_count != 2) {
                pr_err("reset-controller does not conform to reset-cells\n");
                return -EINVAL;
        }

        *base = of_iomap(args.np, 0);
        if (!*base) {
                pr_err("failed remapping PMB register\n");
                return -ENOMEM;
        }

        /* We do not need the number of zones */
        *addr = args.args[0];

        return 0;
}

int bcm63xx_pmb_power_on_cpu(struct device_node *dn)
{
        void __iomem *base;
        unsigned int cpu, addr;
        unsigned long flags;
        u32 val, ctrl;
        int ret;

        ret = bcm63xx_pmb_get_resources(dn, &base, &cpu, &addr);
        if (ret)
                return ret;

        /* We would not know how to enable a third and greater CPU */
        WARN_ON(cpu > 1);

        spin_lock_irqsave(&pmb_lock, flags);

        /* Check if the CPU is already on and save the ARM_CONTROL register
         * value since we will use it later for CPU de-assert once done with
         * the CPU-specific power sequence
         */
        ret = bpcm_rd(base, addr, ARM_CONTROL, &ctrl);
        if (ret)
                goto out;

        if (ctrl & CPU_RESET_N(cpu)) {
                pr_info("PMB: CPU%d is already powered on\n", cpu);
                ret = 0;
                goto out;
        }

        /* Power on PLL */
        ret = bpcm_rd(base, addr, ARM_PWR_CONTROL(cpu), &val);
        if (ret)
                goto out;

        val |= (PWR_CPU_MASK << PWR_ON_SHIFT);

        ret = bpcm_wr_rd_mask(base, addr, ARM_PWR_CONTROL(cpu), &val,
                        PWR_ON_STATUS_SHIFT, PWR_CPU_MASK, PWR_CPU_MASK);
        if (ret)
                goto out;

        val |= (PWR_CPU_MASK << PWR_OK_SHIFT);

        ret = bpcm_wr_rd_mask(base, addr, ARM_PWR_CONTROL(cpu), &val,
                        PWR_OK_STATUS_SHIFT, PWR_CPU_MASK, PWR_CPU_MASK);
        if (ret)
                goto out;

        val &= ~CLAMP_ON;

        ret = bpcm_wr(base, addr, ARM_PWR_CONTROL(cpu), val);
        if (ret)
                goto out;

        /* Power on CPU<N> RAM */
        val &= ~(MEM_PDA_MASK << MEM_PDA_SHIFT);

        ret = bpcm_wr(base, addr, ARM_PWR_CONTROL(cpu), val);
        if (ret)
                goto out;

        val |= MEM_PWR_ON;

        ret = bpcm_wr_rd_mask(base, addr, ARM_PWR_CONTROL(cpu), &val,
                        0, MEM_PWR_ON_STATUS, MEM_PWR_ON_STATUS);
        if (ret)
                goto out;

        val |= MEM_PWR_OK;

        ret = bpcm_wr_rd_mask(base, addr, ARM_PWR_CONTROL(cpu), &val,
                        0, MEM_PWR_OK_STATUS, MEM_PWR_OK_STATUS);
        if (ret)
                goto out;

        val &= ~MEM_CLAMP_ON;

        ret = bpcm_wr(base, addr, ARM_PWR_CONTROL(cpu), val);
        if (ret)
                goto out;

        /* De-assert CPU reset */
        ctrl |= CPU_RESET_N(cpu);

        ret = bpcm_wr(base, addr, ARM_CONTROL, ctrl);
out:
        spin_unlock_irqrestore(&pmb_lock, flags);
        iounmap(base);
        return ret;
}