/*
 * Copyright (C) 2016 IBM Corp.
 *
 * 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/mfd/syscon.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/string.h>
#include "../core.h"
#include "pinctrl-aspeed.h"

static const char *const aspeed_pinmux_ips[] = {
        [ASPEED_IP_SCU] = "SCU",
        [ASPEED_IP_GFX] = "GFX",
        [ASPEED_IP_LPC] = "LPC",
};

int aspeed_pinctrl_get_groups_count(struct pinctrl_dev *pctldev)
{
        struct aspeed_pinctrl_data *pdata = pinctrl_dev_get_drvdata(pctldev);

        return pdata->ngroups;
}

const char *aspeed_pinctrl_get_group_name(struct pinctrl_dev *pctldev,
                unsigned int group)
{
        struct aspeed_pinctrl_data *pdata = pinctrl_dev_get_drvdata(pctldev);

        return pdata->groups[group].name;
}

int aspeed_pinctrl_get_group_pins(struct pinctrl_dev *pctldev,
                                  unsigned int group, const unsigned int **pins,
                                  unsigned int *npins)
{
        struct aspeed_pinctrl_data *pdata = pinctrl_dev_get_drvdata(pctldev);

        *pins = &pdata->groups[group].pins[0];
        *npins = pdata->groups[group].npins;

        return 0;
}

void aspeed_pinctrl_pin_dbg_show(struct pinctrl_dev *pctldev,
                                 struct seq_file *s, unsigned int offset)
{
        seq_printf(s, " %s", dev_name(pctldev->dev));
}

int aspeed_pinmux_get_fn_count(struct pinctrl_dev *pctldev)
{
        struct aspeed_pinctrl_data *pdata = pinctrl_dev_get_drvdata(pctldev);

        return pdata->nfunctions;
}

const char *aspeed_pinmux_get_fn_name(struct pinctrl_dev *pctldev,
                                      unsigned int function)
{
        struct aspeed_pinctrl_data *pdata = pinctrl_dev_get_drvdata(pctldev);

        return pdata->functions[function].name;
}

int aspeed_pinmux_get_fn_groups(struct pinctrl_dev *pctldev,
                                unsigned int function,
                                const char * const **groups,
                                unsigned int * const num_groups)
{
        struct aspeed_pinctrl_data *pdata = pinctrl_dev_get_drvdata(pctldev);

        *groups = pdata->functions[function].groups;
        *num_groups = pdata->functions[function].ngroups;

        return 0;
}

static inline void aspeed_sig_desc_print_val(
                const struct aspeed_sig_desc *desc, bool enable, u32 rv)
{
        pr_debug("Want %s%X[0x%08X]=0x%X, got 0x%X from 0x%08X\n",
                        aspeed_pinmux_ips[desc->ip], desc->reg,
                        desc->mask, enable ? desc->enable : desc->disable,
                        (rv & desc->mask) >> __ffs(desc->mask), rv);
}

/**
 * Query the enabled or disabled state of a signal descriptor
 *
 * @desc: The signal descriptor of interest
 * @enabled: True to query the enabled state, false to query disabled state
 * @regmap: The IP block's regmap instance
 *
 * Return: 1 if the descriptor's bitfield is configured to the state
 * selected by @enabled, 0 if not, and less than zero if an unrecoverable
 * failure occurred
 *
 * Evaluation of descriptor state is non-trivial in that it is not a binary
 * outcome: The bitfields can be greater than one bit in size and thus can take
 * a value that is neither the enabled nor disabled state recorded in the
 * descriptor (typically this means a different function to the one of interest
 * is enabled). Thus we must explicitly test for either condition as required.
 */
static int aspeed_sig_desc_eval(const struct aspeed_sig_desc *desc,
                                 bool enabled, struct regmap *map)
{
        int ret;
        unsigned int raw;
        u32 want;

        if (!map)
                return -ENODEV;

        ret = regmap_read(map, desc->reg, &raw);
        if (ret)
                return ret;

        aspeed_sig_desc_print_val(desc, enabled, raw);
        want = enabled ? desc->enable : desc->disable;

        return ((raw & desc->mask) >> __ffs(desc->mask)) == want;
}

/**
 * Query the enabled or disabled state for a mux function's signal on a pin
 *
 * @expr: An expression controlling the signal for a mux function on a pin
 * @enabled: True to query the enabled state, false to query disabled state
 * @maps: The list of regmap instances
 *
 * Return: 1 if the expression composed by @enabled evaluates true, 0 if not,
 * and less than zero if an unrecoverable failure occurred.
 *
 * A mux function is enabled or disabled if the function's signal expression
 * for each pin in the function's pin group evaluates true for the desired
 * state. An signal expression evaluates true if all of its associated signal
 * descriptors evaluate true for the desired state.
 *
 * If an expression's state is described by more than one bit, either through
 * multi-bit bitfields in a single signal descriptor or through multiple signal
 * descriptors of a single bit then it is possible for the expression to be in
 * neither the enabled nor disabled state. Thus we must explicitly test for
 * either condition as required.
 */
static int aspeed_sig_expr_eval(const struct aspeed_sig_expr *expr,
                                 bool enabled, struct regmap * const *maps)
{
        int i;
        int ret;

        for (i = 0; i < expr->ndescs; i++) {
                const struct aspeed_sig_desc *desc = &expr->descs[i];

                ret = aspeed_sig_desc_eval(desc, enabled, maps[desc->ip]);
                if (ret <= 0)
                        return ret;
        }

        return 1;
}

/**
 * Configure a pin's signal by applying an expression's descriptor state for
 * all descriptors in the expression.
 *
 * @expr: The expression associated with the function whose signal is to be
 *        configured
 * @enable: true to enable an function's signal through a pin's signal
 *          expression, false to disable the function's signal
 * @maps: The list of regmap instances for pinmux register access.
 *
 * Return: 0 if the expression is configured as requested and a negative error
 * code otherwise
 */
static int aspeed_sig_expr_set(const struct aspeed_sig_expr *expr,
                                bool enable, struct regmap * const *maps)
{
        int ret;
        int i;

        for (i = 0; i < expr->ndescs; i++) {
                const struct aspeed_sig_desc *desc = &expr->descs[i];
                u32 pattern = enable ? desc->enable : desc->disable;
                u32 val = (pattern << __ffs(desc->mask));

                if (!maps[desc->ip])
                        return -ENODEV;

                /*
                 * Strap registers are configured in hardware or by early-boot
                 * firmware. Treat them as read-only despite that we can write
                 * them. This may mean that certain functions cannot be
                 * deconfigured and is the reason we re-evaluate after writing
                 * all descriptor bits.
                 *
                 * Port D and port E GPIO loopback modes are the only exception
                 * as those are commonly used with front-panel buttons to allow
                 * normal operation of the host when the BMC is powered off or
                 * fails to boot. Once the BMC has booted, the loopback mode
                 * must be disabled for the BMC to control host power-on and
                 * reset.
                 */
                if (desc->ip == ASPEED_IP_SCU && desc->reg == HW_STRAP1 &&
                    !(desc->mask & (BIT(21) | BIT(22))))
                        continue;

                if (desc->ip == ASPEED_IP_SCU && desc->reg == HW_STRAP2)
                        continue;

                /* On AST2500, Set bits in SCU7C are cleared from SCU70 */
                if (desc->ip == ASPEED_IP_SCU && desc->reg == HW_STRAP1) {
                        unsigned int rev_id;

                        ret = regmap_read(maps[ASPEED_IP_SCU],
                                HW_REVISION_ID, &rev_id);
                        if (ret < 0)
                                return ret;

                        if (0x04 == (rev_id >> 24)) {
                                u32 value = ~val & desc->mask;

                                if (value) {
                                        ret = regmap_write(maps[desc->ip],
                                                HW_REVISION_ID, value);
                                        if (ret < 0)
                                                return ret;
                                }
                        }
                }

                ret = regmap_update_bits(maps[desc->ip], desc->reg,
                                         desc->mask, val);

                if (ret)
                        return ret;
        }

        ret = aspeed_sig_expr_eval(expr, enable, maps);
        if (ret < 0)
                return ret;

        if (!ret)
                return -EPERM;

        return 0;
}

static int aspeed_sig_expr_enable(const struct aspeed_sig_expr *expr,
                                   struct regmap * const *maps)
{
        int ret;

        ret = aspeed_sig_expr_eval(expr, true, maps);
        if (ret < 0)
                return ret;

        if (!ret)
                return aspeed_sig_expr_set(expr, true, maps);

        return 0;
}

static int aspeed_sig_expr_disable(const struct aspeed_sig_expr *expr,
                                    struct regmap * const *maps)
{
        int ret;

        ret = aspeed_sig_expr_eval(expr, true, maps);
        if (ret < 0)
                return ret;

        if (ret)
                return aspeed_sig_expr_set(expr, false, maps);

        return 0;
}

/**
 * Disable a signal on a pin by disabling all provided signal expressions.
 *
 * @exprs: The list of signal expressions (from a priority level on a pin)
 * @maps: The list of regmap instances for pinmux register access.
 *
 * Return: 0 if all expressions are disabled, otherwise a negative error code
 */
static int aspeed_disable_sig(const struct aspeed_sig_expr **exprs,
                               struct regmap * const *maps)
{
        int ret = 0;

        if (!exprs)
                return true;

        while (*exprs && !ret) {
                ret = aspeed_sig_expr_disable(*exprs, maps);
                exprs++;
        }

        return ret;
}

/**
 * Search for the signal expression needed to enable the pin's signal for the
 * requested function.
 *
 * @exprs: List of signal expressions (haystack)
 * @name: The name of the requested function (needle)
 *
 * Return: A pointer to the signal expression whose function tag matches the
 * provided name, otherwise NULL.
 *
 */
static const struct aspeed_sig_expr *aspeed_find_expr_by_name(
                const struct aspeed_sig_expr **exprs, const char *name)
{
        while (*exprs) {
                if (strcmp((*exprs)->function, name) == 0)
                        return *exprs;
                exprs++;
        }

        return NULL;
}

static char *get_defined_attribute(const struct aspeed_pin_desc *pdesc,
                                   const char *(*get)(
                                           const struct aspeed_sig_expr *))
{
        char *found = NULL;
        size_t len = 0;
        const struct aspeed_sig_expr ***prios, **funcs, *expr;

        prios = pdesc->prios;

        while ((funcs = *prios)) {
                while ((expr = *funcs)) {
                        const char *str = get(expr);
                        size_t delta = strlen(str) + 2;
                        char *expanded;

                        expanded = krealloc(found, len + delta + 1, GFP_KERNEL);
                        if (!expanded) {
                                kfree(found);
                                return expanded;
                        }

                        found = expanded;
                        found[len] = '\0';
                        len += delta;

                        strcat(found, str);
                        strcat(found, ", ");

                        funcs++;
                }
                prios++;
        }

        if (len < 2) {
                kfree(found);
                return NULL;
        }

        found[len - 2] = '\0';

        return found;
}

static const char *aspeed_sig_expr_function(const struct aspeed_sig_expr *expr)
{
        return expr->function;
}

static char *get_defined_functions(const struct aspeed_pin_desc *pdesc)
{
        return get_defined_attribute(pdesc, aspeed_sig_expr_function);
}

static const char *aspeed_sig_expr_signal(const struct aspeed_sig_expr *expr)
{
        return expr->signal;
}

static char *get_defined_signals(const struct aspeed_pin_desc *pdesc)
{
        return get_defined_attribute(pdesc, aspeed_sig_expr_signal);
}

int aspeed_pinmux_set_mux(struct pinctrl_dev *pctldev, unsigned int function,
                          unsigned int group)
{
        int i;
        int ret;
        const struct aspeed_pinctrl_data *pdata =
                pinctrl_dev_get_drvdata(pctldev);
        const struct aspeed_pin_group *pgroup = &pdata->groups[group];
        const struct aspeed_pin_function *pfunc =
                &pdata->functions[function];

        for (i = 0; i < pgroup->npins; i++) {
                int pin = pgroup->pins[i];
                const struct aspeed_pin_desc *pdesc = pdata->pins[pin].drv_data;
                const struct aspeed_sig_expr *expr = NULL;
                const struct aspeed_sig_expr **funcs;
                const struct aspeed_sig_expr ***prios;

                pr_debug("Muxing pin %d for %s\n", pin, pfunc->name);

                if (!pdesc)
                        return -EINVAL;

                prios = pdesc->prios;

                if (!prios)
                        continue;

                /* Disable functions at a higher priority than that requested */
                while ((funcs = *prios)) {
                        expr = aspeed_find_expr_by_name(funcs, pfunc->name);

                        if (expr)
                                break;

                        ret = aspeed_disable_sig(funcs, pdata->maps);
                        if (ret)
                                return ret;

                        prios++;
                }

                if (!expr) {
                        char *functions = get_defined_functions(pdesc);
                        char *signals = get_defined_signals(pdesc);

                        pr_warn("No function %s found on pin %s (%d). Found signal(s) %s for function(s) %s\n",
                                pfunc->name, pdesc->name, pin, signals,
                                functions);
                        kfree(signals);
                        kfree(functions);

                        return -ENXIO;
                }

                ret = aspeed_sig_expr_enable(expr, pdata->maps);
                if (ret)
                        return ret;
        }

        return 0;
}

static bool aspeed_expr_is_gpio(const struct aspeed_sig_expr *expr)
{
        /*
         * The signal type is GPIO if the signal name has "GPIO" as a prefix.
         * strncmp (rather than strcmp) is used to implement the prefix
         * requirement.
         *
         * expr->signal might look like "GPIOT3" in the GPIO case.
         */
        return strncmp(expr->signal, "GPIO", 4) == 0;
}

static bool aspeed_gpio_in_exprs(const struct aspeed_sig_expr **exprs)
{
        if (!exprs)
                return false;

        while (*exprs) {
                if (aspeed_expr_is_gpio(*exprs))
                        return true;
                exprs++;
        }

        return false;
}

int aspeed_gpio_request_enable(struct pinctrl_dev *pctldev,
                               struct pinctrl_gpio_range *range,
                               unsigned int offset)
{
        int ret;
        const struct aspeed_pinctrl_data *pdata =
                pinctrl_dev_get_drvdata(pctldev);
        const struct aspeed_pin_desc *pdesc = pdata->pins[offset].drv_data;
        const struct aspeed_sig_expr ***prios, **funcs, *expr;

        if (!pdesc)
                return -EINVAL;

        prios = pdesc->prios;

        if (!prios)
                return -ENXIO;

        /* Disable any functions of higher priority than GPIO */
        while ((funcs = *prios)) {
                if (aspeed_gpio_in_exprs(funcs))
                        break;

                ret = aspeed_disable_sig(funcs, pdata->maps);
                if (ret)
                        return ret;

                prios++;
        }

        if (!funcs) {
                char *signals = get_defined_signals(pdesc);

                pr_warn("No GPIO signal type found on pin %s (%d). Found: %s\n",
                        pdesc->name, offset, signals);
                kfree(signals);

                return -ENXIO;
        }

        expr = *funcs;

        /*
         * Disabling all higher-priority expressions is enough to enable the
         * lowest-priority signal type. As such it has no associated
         * expression.
         */
        if (!expr)
                return 0;

        /*
         * If GPIO is not the lowest priority signal type, assume there is only
         * one expression defined to enable the GPIO function
         */
        return aspeed_sig_expr_enable(expr, pdata->maps);
}

int aspeed_pinctrl_probe(struct platform_device *pdev,
                         struct pinctrl_desc *pdesc,
                         struct aspeed_pinctrl_data *pdata)
{
        struct device *parent;
        struct pinctrl_dev *pctl;

        parent = pdev->dev.parent;
        if (!parent) {
                dev_err(&pdev->dev, "No parent for syscon pincontroller\n");
                return -ENODEV;
        }

        pdata->maps[ASPEED_IP_SCU] = syscon_node_to_regmap(parent->of_node);
        if (IS_ERR(pdata->maps[ASPEED_IP_SCU])) {
                dev_err(&pdev->dev, "No regmap for syscon pincontroller parent\n");
                return PTR_ERR(pdata->maps[ASPEED_IP_SCU]);
        }

        pctl = pinctrl_register(pdesc, &pdev->dev, pdata);

        if (IS_ERR(pctl)) {
                dev_err(&pdev->dev, "Failed to register pinctrl\n");
                return PTR_ERR(pctl);
        }

        platform_set_drvdata(pdev, pdata);

        return 0;
}

static inline bool pin_in_config_range(unsigned int offset,
                const struct aspeed_pin_config *config)
{
        return offset >= config->pins[0] && offset <= config->pins[1];
}

static inline const struct aspeed_pin_config *find_pinconf_config(
                const struct aspeed_pinctrl_data *pdata,
                unsigned int offset,
                enum pin_config_param param)
{
        unsigned int i;

        for (i = 0; i < pdata->nconfigs; i++) {
                if (param == pdata->configs[i].param &&
                                pin_in_config_range(offset, &pdata->configs[i]))
                        return &pdata->configs[i];
        }

        return NULL;
}

/**
 * @param: pinconf configuration parameter
 * @arg: The supported argument for @param, or -1 if any value is supported
 * @value: The register value to write to configure @arg for @param
 *
 * The map is to be used in conjunction with the configuration array supplied
 * by the driver implementation.
 */
struct aspeed_pin_config_map {
        enum pin_config_param param;
        s32 arg;
        u32 val;
};

enum aspeed_pin_config_map_type { MAP_TYPE_ARG, MAP_TYPE_VAL };

/* Aspeed consistently both:
 *
 * 1. Defines "disable bits" for internal pull-downs
 * 2. Uses 8mA or 16mA drive strengths
 */
static const struct aspeed_pin_config_map pin_config_map[] = {
        { PIN_CONFIG_BIAS_PULL_DOWN,  0, 1 },
        { PIN_CONFIG_BIAS_PULL_DOWN, -1, 0 },
        { PIN_CONFIG_BIAS_DISABLE,   -1, 1 },
        { PIN_CONFIG_DRIVE_STRENGTH,  8, 0 },
        { PIN_CONFIG_DRIVE_STRENGTH, 16, 1 },
};

static const struct aspeed_pin_config_map *find_pinconf_map(
                enum pin_config_param param,
                enum aspeed_pin_config_map_type type,
                s64 value)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(pin_config_map); i++) {
                const struct aspeed_pin_config_map *elem;
                bool match;

                elem = &pin_config_map[i];

                switch (type) {
                case MAP_TYPE_ARG:
                        match = (elem->arg == -1 || elem->arg == value);
                        break;
                case MAP_TYPE_VAL:
                        match = (elem->val == value);
                        break;
                }

                if (param == elem->param && match)
                        return elem;
        }

        return NULL;
}

int aspeed_pin_config_get(struct pinctrl_dev *pctldev, unsigned int offset,
                unsigned long *config)
{
        const enum pin_config_param param = pinconf_to_config_param(*config);
        const struct aspeed_pin_config_map *pmap;
        const struct aspeed_pinctrl_data *pdata;
        const struct aspeed_pin_config *pconf;
        unsigned int val;
        int rc = 0;
        u32 arg;

        pdata = pinctrl_dev_get_drvdata(pctldev);
        pconf = find_pinconf_config(pdata, offset, param);
        if (!pconf)
                return -ENOTSUPP;

        rc = regmap_read(pdata->maps[ASPEED_IP_SCU], pconf->reg, &val);
        if (rc < 0)
                return rc;

        pmap = find_pinconf_map(param, MAP_TYPE_VAL,
                        (val & BIT(pconf->bit)) >> pconf->bit);

        if (!pmap)
                return -EINVAL;

        if (param == PIN_CONFIG_DRIVE_STRENGTH)
                arg = (u32) pmap->arg;
        else if (param == PIN_CONFIG_BIAS_PULL_DOWN)
                arg = !!pmap->arg;
        else
                arg = 1;

        if (!arg)
                return -EINVAL;

        *config = pinconf_to_config_packed(param, arg);

        return 0;
}

int aspeed_pin_config_set(struct pinctrl_dev *pctldev, unsigned int offset,
                unsigned long *configs, unsigned int num_configs)
{
        const struct aspeed_pinctrl_data *pdata;
        unsigned int i;
        int rc = 0;

        pdata = pinctrl_dev_get_drvdata(pctldev);

        for (i = 0; i < num_configs; i++) {
                const struct aspeed_pin_config_map *pmap;
                const struct aspeed_pin_config *pconf;
                enum pin_config_param param;
                unsigned int val;
                u32 arg;

                param = pinconf_to_config_param(configs[i]);
                arg = pinconf_to_config_argument(configs[i]);

                pconf = find_pinconf_config(pdata, offset, param);
                if (!pconf)
                        return -ENOTSUPP;

                pmap = find_pinconf_map(param, MAP_TYPE_ARG, arg);

                if (unlikely(WARN_ON(!pmap)))
                        return -EINVAL;

                val = pmap->val << pconf->bit;

                rc = regmap_update_bits(pdata->maps[ASPEED_IP_SCU], pconf->reg,
                                BIT(pconf->bit), val);

                if (rc < 0)
                        return rc;

                pr_debug("%s: Set SCU%02X[%d]=%d for param %d(=%d) on pin %d\n",
                                __func__, pconf->reg, pconf->bit, pmap->val,
                                param, arg, offset);
        }

        return 0;
}

int aspeed_pin_config_group_get(struct pinctrl_dev *pctldev,
                unsigned int selector,
                unsigned long *config)
{
        const unsigned int *pins;
        unsigned int npins;
        int rc;

        rc = aspeed_pinctrl_get_group_pins(pctldev, selector, &pins, &npins);
        if (rc < 0)
                return rc;

        if (!npins)
                return -ENODEV;

        rc = aspeed_pin_config_get(pctldev, pins[0], config);

        return rc;
}

int aspeed_pin_config_group_set(struct pinctrl_dev *pctldev,
                unsigned int selector,
                unsigned long *configs,
                unsigned int num_configs)
{
        const unsigned int *pins;
        unsigned int npins;
        int rc;
        int i;

        pr_debug("%s: Fetching pins for group selector %d\n",
                        __func__, selector);
        rc = aspeed_pinctrl_get_group_pins(pctldev, selector, &pins, &npins);
        if (rc < 0)
                return rc;

        for (i = 0; i < npins; i++) {
                rc = aspeed_pin_config_set(pctldev, pins[i], configs,
                                num_configs);
                if (rc < 0)
                        return rc;
        }

        return 0;
}