/*
 * Driver for the ICST307 VCO clock found in the ARM Reference designs.
 * We wrap the custom interface from <asm/hardware/icst.h> into the generic
 * clock framework.
 *
 * Copyright (C) 2012-2015 Linus Walleij
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * TODO: when all ARM reference designs are migrated to generic clocks, the
 * ICST clock code from the ARM tree should probably be merged into this
 * file.
 */
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/err.h>
#include <linux/clk-provider.h>
#include <linux/io.h>
#include <linux/regmap.h>
#include <linux/mfd/syscon.h>

#include "icst.h"
#include "clk-icst.h"

/* Magic unlocking token used on all Versatile boards */
#define VERSATILE_LOCK_VAL      0xA05F

#define VERSATILE_AUX_OSC_BITS 0x7FFFF
#define INTEGRATOR_AP_CM_BITS 0xFF
#define INTEGRATOR_AP_SYS_BITS 0xFF
#define INTEGRATOR_CP_CM_CORE_BITS 0x7FF
#define INTEGRATOR_CP_CM_MEM_BITS 0x7FF000

#define INTEGRATOR_AP_PCI_25_33_MHZ BIT(8)

/**
 * enum icst_control_type - the type of ICST control register
 */
enum icst_control_type {
        ICST_VERSATILE, /* The standard type, all control bits available */
        ICST_INTEGRATOR_AP_CM, /* Only 8 bits of VDW available */
        ICST_INTEGRATOR_AP_SYS, /* Only 8 bits of VDW available */
        ICST_INTEGRATOR_AP_PCI, /* Odd bit pattern storage */
        ICST_INTEGRATOR_CP_CM_CORE, /* Only 8 bits of VDW and 3 bits of OD */
        ICST_INTEGRATOR_CP_CM_MEM, /* Only 8 bits of VDW and 3 bits of OD */
};

/**
 * struct clk_icst - ICST VCO clock wrapper
 * @hw: corresponding clock hardware entry
 * @vcoreg: VCO register address
 * @lockreg: VCO lock register address
 * @params: parameters for this ICST instance
 * @rate: current rate
 * @ctype: the type of control register for the ICST
 */
struct clk_icst {
        struct clk_hw hw;
        struct regmap *map;
        u32 vcoreg_off;
        u32 lockreg_off;
        struct icst_params *params;
        unsigned long rate;
        enum icst_control_type ctype;
};

#define to_icst(_hw) container_of(_hw, struct clk_icst, hw)

/**
 * vco_get() - get ICST VCO settings from a certain ICST
 * @icst: the ICST clock to get
 * @vco: the VCO struct to return the value in
 */
static int vco_get(struct clk_icst *icst, struct icst_vco *vco)
{
        u32 val;
        int ret;

        ret = regmap_read(icst->map, icst->vcoreg_off, &val);
        if (ret)
                return ret;

        /*
         * The Integrator/AP core clock can only access the low eight
         * bits of the v PLL divider. Bit 8 is tied low and always zero,
         * r is hardwired to 22 and output divider s is hardwired to 1
         * (divide by 2) according to the document
         * "Integrator CM926EJ-S, CM946E-S, CM966E-S, CM1026EJ-S and
         * CM1136JF-S User Guide" ARM DUI 0138E, page 3-13 thru 3-14.
         */
        if (icst->ctype == ICST_INTEGRATOR_AP_CM) {
                vco->v = val & INTEGRATOR_AP_CM_BITS;
                vco->r = 22;
                vco->s = 1;
                return 0;
        }

        /*
         * The Integrator/AP system clock on the base board can only
         * access the low eight bits of the v PLL divider. Bit 8 is tied low
         * and always zero, r is hardwired to 46, and the output divider is
         * hardwired to 3 (divide by 4) according to the document
         * "Integrator AP ASIC Development Motherboard" ARM DUI 0098B,
         * page 3-16.
         */
        if (icst->ctype == ICST_INTEGRATOR_AP_SYS) {
                vco->v = val & INTEGRATOR_AP_SYS_BITS;
                vco->r = 46;
                vco->s = 3;
                return 0;
        }

        /*
         * The Integrator/AP PCI clock is using an odd pattern to create
         * the child clock, basically a single bit called DIVX/Y is used
         * to select between two different hardwired values: setting the
         * bit to 0 yields v = 17, r = 22 and OD = 1, whereas setting the
         * bit to 1 yields v = 14, r = 14 and OD = 1 giving the frequencies
         * 33 or 25 MHz respectively.
         */
        if (icst->ctype == ICST_INTEGRATOR_AP_PCI) {
                bool divxy = !!(val & INTEGRATOR_AP_PCI_25_33_MHZ);

                vco->v = divxy ? 17 : 14;
                vco->r = divxy ? 22 : 14;
                vco->s = 1;
                return 0;
        }

        /*
         * The Integrator/CP core clock can access the low eight bits
         * of the v PLL divider. Bit 8 is tied low and always zero,
         * r is hardwired to 22 and the output divider s is accessible
         * in bits 8 thru 10 according to the document
         * "Integrator/CM940T, CM920T, CM740T, and CM720T User Guide"
         * ARM DUI 0157A, page 3-20 thru 3-23 and 4-10.
         */
        if (icst->ctype == ICST_INTEGRATOR_CP_CM_CORE) {
                vco->v = val & 0xFF;
                vco->r = 22;
                vco->s = (val >> 8) & 7;
                return 0;
        }

        if (icst->ctype == ICST_INTEGRATOR_CP_CM_MEM) {
                vco->v = (val >> 12) & 0xFF;
                vco->r = 22;
                vco->s = (val >> 20) & 7;
                return 0;
        }

        vco->v = val & 0x1ff;
        vco->r = (val >> 9) & 0x7f;
        vco->s = (val >> 16) & 03;
        return 0;
}

/**
 * vco_set() - commit changes to an ICST VCO
 * @icst: the ICST clock to set
 * @vco: the VCO struct to set the changes from
 */
static int vco_set(struct clk_icst *icst, struct icst_vco vco)
{
        u32 mask;
        u32 val;
        int ret;

        /* Mask the bits used by the VCO */
        switch (icst->ctype) {
        case ICST_INTEGRATOR_AP_CM:
                mask = INTEGRATOR_AP_CM_BITS;
                val = vco.v & 0xFF;
                if (vco.v & 0x100)
                        pr_err("ICST error: tried to set bit 8 of VDW\n");
                if (vco.s != 1)
                        pr_err("ICST error: tried to use VOD != 1\n");
                if (vco.r != 22)
                        pr_err("ICST error: tried to use RDW != 22\n");
                break;
        case ICST_INTEGRATOR_AP_SYS:
                mask = INTEGRATOR_AP_SYS_BITS;
                val = vco.v & 0xFF;
                if (vco.v & 0x100)
                        pr_err("ICST error: tried to set bit 8 of VDW\n");
                if (vco.s != 3)
                        pr_err("ICST error: tried to use VOD != 1\n");
                if (vco.r != 46)
                        pr_err("ICST error: tried to use RDW != 22\n");
                break;
        case ICST_INTEGRATOR_CP_CM_CORE:
                mask = INTEGRATOR_CP_CM_CORE_BITS; /* Uses 12 bits */
                val = (vco.v & 0xFF) | vco.s << 8;
                if (vco.v & 0x100)
                        pr_err("ICST error: tried to set bit 8 of VDW\n");
                if (vco.r != 22)
                        pr_err("ICST error: tried to use RDW != 22\n");
                break;
        case ICST_INTEGRATOR_CP_CM_MEM:
                mask = INTEGRATOR_CP_CM_MEM_BITS; /* Uses 12 bits */
                val = ((vco.v & 0xFF) << 12) | (vco.s << 20);
                if (vco.v & 0x100)
                        pr_err("ICST error: tried to set bit 8 of VDW\n");
                if (vco.r != 22)
                        pr_err("ICST error: tried to use RDW != 22\n");
                break;
        default:
                /* Regular auxilary oscillator */
                mask = VERSATILE_AUX_OSC_BITS;
                val = vco.v | (vco.r << 9) | (vco.s << 16);
                break;
        }

        pr_debug("ICST: new val = 0x%08x\n", val);

        /* This magic unlocks the VCO so it can be controlled */
        ret = regmap_write(icst->map, icst->lockreg_off, VERSATILE_LOCK_VAL);
        if (ret)
                return ret;
        ret = regmap_update_bits(icst->map, icst->vcoreg_off, mask, val);
        if (ret)
                return ret;
        /* This locks the VCO again */
        ret = regmap_write(icst->map, icst->lockreg_off, 0);
        if (ret)
                return ret;
        return 0;
}

static unsigned long icst_recalc_rate(struct clk_hw *hw,
                                      unsigned long parent_rate)
{
        struct clk_icst *icst = to_icst(hw);
        struct icst_vco vco;
        int ret;

        if (parent_rate)
                icst->params->ref = parent_rate;
        ret = vco_get(icst, &vco);
        if (ret) {
                pr_err("ICST: could not get VCO setting\n");
                return 0;
        }
        icst->rate = icst_hz(icst->params, vco);
        return icst->rate;
}

static long icst_round_rate(struct clk_hw *hw, unsigned long rate,
                            unsigned long *prate)
{
        struct clk_icst *icst = to_icst(hw);
        struct icst_vco vco;

        if (icst->ctype == ICST_INTEGRATOR_AP_CM ||
            icst->ctype == ICST_INTEGRATOR_CP_CM_CORE) {
                if (rate <= 12000000)
                        return 12000000;
                if (rate >= 160000000)
                        return 160000000;
                /* Slam to closest megahertz */
                return DIV_ROUND_CLOSEST(rate, 1000000) * 1000000;
        }

        if (icst->ctype == ICST_INTEGRATOR_CP_CM_MEM) {
                if (rate <= 6000000)
                        return 6000000;
                if (rate >= 66000000)
                        return 66000000;
                /* Slam to closest 0.5 megahertz */
                return DIV_ROUND_CLOSEST(rate, 500000) * 500000;
        }

        if (icst->ctype == ICST_INTEGRATOR_AP_SYS) {
                /* Divides between 3 and 50 MHz in steps of 0.25 MHz */
                if (rate <= 3000000)
                        return 3000000;
                if (rate >= 50000000)
                        return 5000000;
                /* Slam to closest 0.25 MHz */
                return DIV_ROUND_CLOSEST(rate, 250000) * 250000;
        }

        if (icst->ctype == ICST_INTEGRATOR_AP_PCI) {
                /*
                 * If we're below or less than halfway from 25 to 33 MHz
                 * select 25 MHz
                 */
                if (rate <= 25000000 || rate < 29000000)
                        return 25000000;
                /* Else just return the default frequency */
                return 33000000;
        }

        vco = icst_hz_to_vco(icst->params, rate);
        return icst_hz(icst->params, vco);
}

static int icst_set_rate(struct clk_hw *hw, unsigned long rate,
                         unsigned long parent_rate)
{
        struct clk_icst *icst = to_icst(hw);
        struct icst_vco vco;

        if (icst->ctype == ICST_INTEGRATOR_AP_PCI) {
                /* This clock is especially primitive */
                unsigned int val;
                int ret;

                if (rate == 25000000) {
                        val = 0;
                } else if (rate == 33000000) {
                        val = INTEGRATOR_AP_PCI_25_33_MHZ;
                } else {
                        pr_err("ICST: cannot set PCI frequency %lu\n",
                               rate);
                        return -EINVAL;
                }
                ret = regmap_write(icst->map, icst->lockreg_off,
                                   VERSATILE_LOCK_VAL);
                if (ret)
                        return ret;
                ret = regmap_update_bits(icst->map, icst->vcoreg_off,
                                         INTEGRATOR_AP_PCI_25_33_MHZ,
                                         val);
                if (ret)
                        return ret;
                /* This locks the VCO again */
                ret = regmap_write(icst->map, icst->lockreg_off, 0);
                if (ret)
                        return ret;
                return 0;
        }

        if (parent_rate)
                icst->params->ref = parent_rate;
        vco = icst_hz_to_vco(icst->params, rate);
        icst->rate = icst_hz(icst->params, vco);
        return vco_set(icst, vco);
}

static const struct clk_ops icst_ops = {
        .recalc_rate = icst_recalc_rate,
        .round_rate = icst_round_rate,
        .set_rate = icst_set_rate,
};

static struct clk *icst_clk_setup(struct device *dev,
                                  const struct clk_icst_desc *desc,
                                  const char *name,
                                  const char *parent_name,
                                  struct regmap *map,
                                  enum icst_control_type ctype)
{
        struct clk *clk;
        struct clk_icst *icst;
        struct clk_init_data init;
        struct icst_params *pclone;

        icst = kzalloc(sizeof(*icst), GFP_KERNEL);
        if (!icst)
                return ERR_PTR(-ENOMEM);

        pclone = kmemdup(desc->params, sizeof(*pclone), GFP_KERNEL);
        if (!pclone) {
                kfree(icst);
                return ERR_PTR(-ENOMEM);
        }

        init.name = name;
        init.ops = &icst_ops;
        init.flags = 0;
        init.parent_names = (parent_name ? &parent_name : NULL);
        init.num_parents = (parent_name ? 1 : 0);
        icst->map = map;
        icst->hw.init = &init;
        icst->params = pclone;
        icst->vcoreg_off = desc->vco_offset;
        icst->lockreg_off = desc->lock_offset;
        icst->ctype = ctype;

        clk = clk_register(dev, &icst->hw);
        if (IS_ERR(clk)) {
                kfree(pclone);
                kfree(icst);
        }

        return clk;
}

struct clk *icst_clk_register(struct device *dev,
                        const struct clk_icst_desc *desc,
                        const char *name,
                        const char *parent_name,
                        void __iomem *base)
{
        struct regmap_config icst_regmap_conf = {
                .reg_bits = 32,
                .val_bits = 32,
                .reg_stride = 4,
        };
        struct regmap *map;

        map = regmap_init_mmio(dev, base, &icst_regmap_conf);
        if (IS_ERR(map)) {
                pr_err("could not initialize ICST regmap\n");
                return ERR_CAST(map);
        }
        return icst_clk_setup(dev, desc, name, parent_name, map,
                              ICST_VERSATILE);
}
EXPORT_SYMBOL_GPL(icst_clk_register);

#ifdef CONFIG_OF
/*
 * In a device tree, an memory-mapped ICST clock appear as a child
 * of a syscon node. Assume this and probe it only as a child of a
 * syscon.
 */

static const struct icst_params icst525_params = {
        .vco_max        = ICST525_VCO_MAX_5V,
        .vco_min        = ICST525_VCO_MIN,
        .vd_min         = 8,
        .vd_max         = 263,
        .rd_min         = 3,
        .rd_max         = 65,
        .s2div          = icst525_s2div,
        .idx2s          = icst525_idx2s,
};

static const struct icst_params icst307_params = {
        .vco_max        = ICST307_VCO_MAX,
        .vco_min        = ICST307_VCO_MIN,
        .vd_min         = 4 + 8,
        .vd_max         = 511 + 8,
        .rd_min         = 1 + 2,
        .rd_max         = 127 + 2,
        .s2div          = icst307_s2div,
        .idx2s          = icst307_idx2s,
};

/**
 * The core modules on the Integrator/AP and Integrator/CP have
 * especially crippled ICST525 control.
 */
static const struct icst_params icst525_apcp_cm_params = {
        .vco_max        = ICST525_VCO_MAX_5V,
        .vco_min        = ICST525_VCO_MIN,
        /* Minimum 12 MHz, VDW = 4 */
        .vd_min         = 12,
        /*
         * Maximum 160 MHz, VDW = 152 for all core modules, but
         * CM926EJ-S, CM1026EJ-S and CM1136JF-S can actually
         * go to 200 MHz (max VDW = 192).
         */
        .vd_max         = 192,
        /* r is hardcoded to 22 and this is the actual divisor, +2 */
        .rd_min         = 24,
        .rd_max         = 24,
        .s2div          = icst525_s2div,
        .idx2s          = icst525_idx2s,
};

static const struct icst_params icst525_ap_sys_params = {
        .vco_max        = ICST525_VCO_MAX_5V,
        .vco_min        = ICST525_VCO_MIN,
        /* Minimum 3 MHz, VDW = 4 */
        .vd_min         = 3,
        /* Maximum 50 MHz, VDW = 192 */
        .vd_max         = 50,
        /* r is hardcoded to 46 and this is the actual divisor, +2 */
        .rd_min         = 48,
        .rd_max         = 48,
        .s2div          = icst525_s2div,
        .idx2s          = icst525_idx2s,
};

static const struct icst_params icst525_ap_pci_params = {
        .vco_max        = ICST525_VCO_MAX_5V,
        .vco_min        = ICST525_VCO_MIN,
        /* Minimum 25 MHz */
        .vd_min         = 25,
        /* Maximum 33 MHz */
        .vd_max         = 33,
        /* r is hardcoded to 14 or 22 and this is the actual divisors +2 */
        .rd_min         = 16,
        .rd_max         = 24,
        .s2div          = icst525_s2div,
        .idx2s          = icst525_idx2s,
};

static void __init of_syscon_icst_setup(struct device_node *np)
{
        struct device_node *parent;
        struct regmap *map;
        struct clk_icst_desc icst_desc;
        const char *name = np->name;
        const char *parent_name;
        struct clk *regclk;
        enum icst_control_type ctype;

        /* We do not release this reference, we are using it perpetually */
        parent = of_get_parent(np);
        if (!parent) {
                pr_err("no parent node for syscon ICST clock\n");
                return;
        }
        map = syscon_node_to_regmap(parent);
        if (IS_ERR(map)) {
                pr_err("no regmap for syscon ICST clock parent\n");
                return;
        }

        if (of_property_read_u32(np, "vco-offset", &icst_desc.vco_offset)) {
                pr_err("no VCO register offset for ICST clock\n");
                return;
        }
        if (of_property_read_u32(np, "lock-offset", &icst_desc.lock_offset)) {
                pr_err("no lock register offset for ICST clock\n");
                return;
        }

        if (of_device_is_compatible(np, "arm,syscon-icst525")) {
                icst_desc.params = &icst525_params;
                ctype = ICST_VERSATILE;
        } else if (of_device_is_compatible(np, "arm,syscon-icst307")) {
                icst_desc.params = &icst307_params;
                ctype = ICST_VERSATILE;
        } else if (of_device_is_compatible(np, "arm,syscon-icst525-integratorap-cm")) {
                icst_desc.params = &icst525_apcp_cm_params;
                ctype = ICST_INTEGRATOR_AP_CM;
        } else if (of_device_is_compatible(np, "arm,syscon-icst525-integratorap-sys")) {
                icst_desc.params = &icst525_ap_sys_params;
                ctype = ICST_INTEGRATOR_AP_SYS;
        } else if (of_device_is_compatible(np, "arm,syscon-icst525-integratorap-pci")) {
                icst_desc.params = &icst525_ap_pci_params;
                ctype = ICST_INTEGRATOR_AP_PCI;
        } else if (of_device_is_compatible(np, "arm,syscon-icst525-integratorcp-cm-core")) {
                icst_desc.params = &icst525_apcp_cm_params;
                ctype = ICST_INTEGRATOR_CP_CM_CORE;
        } else if (of_device_is_compatible(np, "arm,syscon-icst525-integratorcp-cm-mem")) {
                icst_desc.params = &icst525_apcp_cm_params;
                ctype = ICST_INTEGRATOR_CP_CM_MEM;
        } else {
                pr_err("unknown ICST clock %s\n", name);
                return;
        }

        /* Parent clock name is not the same as node parent */
        parent_name = of_clk_get_parent_name(np, 0);

        regclk = icst_clk_setup(NULL, &icst_desc, name, parent_name, map, ctype);
        if (IS_ERR(regclk)) {
                pr_err("error setting up syscon ICST clock %s\n", name);
                return;
        }
        of_clk_add_provider(np, of_clk_src_simple_get, regclk);
        pr_debug("registered syscon ICST clock %s\n", name);
}

CLK_OF_DECLARE(arm_syscon_icst525_clk,
               "arm,syscon-icst525", of_syscon_icst_setup);
CLK_OF_DECLARE(arm_syscon_icst307_clk,
               "arm,syscon-icst307", of_syscon_icst_setup);
CLK_OF_DECLARE(arm_syscon_integratorap_cm_clk,
               "arm,syscon-icst525-integratorap-cm", of_syscon_icst_setup);
CLK_OF_DECLARE(arm_syscon_integratorap_sys_clk,
               "arm,syscon-icst525-integratorap-sys", of_syscon_icst_setup);
CLK_OF_DECLARE(arm_syscon_integratorap_pci_clk,
               "arm,syscon-icst525-integratorap-pci", of_syscon_icst_setup);
CLK_OF_DECLARE(arm_syscon_integratorcp_cm_core_clk,
               "arm,syscon-icst525-integratorcp-cm-core", of_syscon_icst_setup);
CLK_OF_DECLARE(arm_syscon_integratorcp_cm_mem_clk,
               "arm,syscon-icst525-integratorcp-cm-mem", of_syscon_icst_setup);
#endif