// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2016 IBM Corp.
 */

#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"

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

        return pdata->pinmux.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->pinmux.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->pinmux.groups[group].pins[0];
        *npins = pdata->pinmux.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->pinmux.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->pinmux.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->pinmux.functions[function].groups;
        *num_groups = pdata->pinmux.functions[function].ngroups;

        return 0;
}

static int aspeed_sig_expr_enable(struct aspeed_pinmux_data *ctx,
                                  const struct aspeed_sig_expr *expr)
{
        int ret;

        pr_debug("Enabling signal %s for %s\n", expr->signal,
                 expr->function);

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

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

        return 0;
}

static int aspeed_sig_expr_disable(struct aspeed_pinmux_data *ctx,
                                   const struct aspeed_sig_expr *expr)
{
        int ret;

        pr_debug("Disabling signal %s for %s\n", expr->signal,
                 expr->function);

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

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

        return 0;
}

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

        if (!exprs)
                return true;

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

        return ret;
}

/**
 * aspeed_find_expr_by_name - 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;
        struct aspeed_pinctrl_data *pdata = pinctrl_dev_get_drvdata(pctldev);
        const struct aspeed_pin_group *pgroup = &pdata->pinmux.groups[group];
        const struct aspeed_pin_function *pfunc =
                &pdata->pinmux.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 %s for %s\n", pdesc->name, 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(&pdata->pinmux, funcs);
                        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(&pdata->pinmux, expr);
                if (ret)
                        return ret;

                pr_debug("Muxed pin %s as %s for %s\n", pdesc->name, expr->signal,
                         expr->function);
        }

        return 0;
}

static bool aspeed_expr_is_gpio(const struct aspeed_sig_expr *expr)
{
        /*
         * We need to differentiate between GPIO and non-GPIO signals to
         * implement the gpio_request_enable() interface. For better or worse
         * the ASPEED pinctrl driver uses the expression names to determine
         * whether an expression will mux a pin for GPIO.
         *
         * Generally we have the following - A GPIO such as B1 has:
         *
         *    - expr->signal set to "GPIOB1"
         *    - expr->function set to "GPIOB1"
         *
         * Using this fact we can determine whether the provided expression is
         * a GPIO expression by testing the signal name for the string prefix
         * "GPIO".
         *
         * However, some GPIOs are input-only, and the ASPEED datasheets name
         * them differently. An input-only GPIO such as T0 has:
         *
         *    - expr->signal set to "GPIT0"
         *    - expr->function set to "GPIT0"
         *
         * It's tempting to generalise the prefix test from "GPIO" to "GPI" to
         * account for both GPIOs and GPIs, but in doing so we run aground on
         * another feature:
         *
         * Some pins in the ASPEED BMC SoCs have a "pass-through" GPIO
         * function where the input state of one pin is replicated as the
         * output state of another (as if they were shorted together - a mux
         * configuration that is typically enabled by hardware strapping).
         * This feature allows the BMC to pass e.g. power button state through
         * to the host while the BMC is yet to boot, but take control of the
         * button state once the BMC has booted by muxing each pin as a
         * separate, pin-specific GPIO.
         *
         * Conceptually this pass-through mode is a form of GPIO and is named
         * as such in the datasheets, e.g. "GPID0". This naming similarity
         * trips us up with the simple GPI-prefixed-signal-name scheme
         * discussed above, as the pass-through configuration is not what we
         * want when muxing a pin as GPIO for the GPIO subsystem.
         *
         * On e.g. the AST2400, a pass-through function "GPID0" is grouped on
         * balls A18 and D16, where we have:
         *
         *    For ball A18:
         *    - expr->signal set to "GPID0IN"
         *    - expr->function set to "GPID0"
         *
         *    For ball D16:
         *    - expr->signal set to "GPID0OUT"
         *    - expr->function set to "GPID0"
         *
         * By contrast, the pin-specific GPIO expressions for the same pins are
         * as follows:
         *
         *    For ball A18:
         *    - expr->signal looks like "GPIOD0"
         *    - expr->function looks like "GPIOD0"
         *
         *    For ball D16:
         *    - expr->signal looks like "GPIOD1"
         *    - expr->function looks like "GPIOD1"
         *
         * Testing both the signal _and_ function names gives us the means
         * differentiate the pass-through GPIO pinmux configuration from the
         * pin-specific configuration that the GPIO subsystem is after: An
         * expression is a pin-specific (non-pass-through) GPIO configuration
         * if the signal prefix is "GPI" and the signal name matches the
         * function name.
         */
        return !strncmp(expr->signal, "GPI", 3) &&
                        !strcmp(expr->signal, expr->function);
}

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;
        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;

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

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

                ret = aspeed_disable_sig(&pdata->pinmux, funcs);
                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) {
                pr_debug("Muxed pin %s as GPIO\n", pdesc->name);
                return 0;
        }

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

        pr_debug("Muxed pin %s as %s\n", pdesc->name, expr->signal);

        return 0;
}

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

        pdata->pinmux.maps[ASPEED_IP_SCU] = pdata->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;
}

enum aspeed_pin_config_map_type { MAP_TYPE_ARG, MAP_TYPE_VAL };

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

        for (i = 0; i < pdata->nconfmaps; i++) {
                const struct aspeed_pin_config_map *elem;
                bool match;

                elem = &pdata->confmaps[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->scu, pconf->reg, &val);
        if (rc < 0)
                return rc;

        pmap = find_pinconf_map(pdata, param, MAP_TYPE_VAL,
                        (val & pconf->mask) >> __ffs(pconf->mask));

        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(pdata, param, MAP_TYPE_ARG, arg);

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

                val = pmap->val << __ffs(pconf->mask);

                rc = regmap_update_bits(pdata->scu, pconf->reg,
                                        pconf->mask, val);

                if (rc < 0)
                        return rc;

                pr_debug("%s: Set SCU%02X[0x%08X]=0x%X for param %d(=%d) on pin %d\n",
                                __func__, pconf->reg, pconf->mask,
                                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;
}