root/drivers/pinctrl/pinctrl-digicolor.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Driver for Conexant Digicolor General Purpose Pin Mapping
 *
 * Author: Baruch Siach <baruch@tkos.co.il>
 *
 * Copyright (C) 2015 Paradox Innovation Ltd.
 *
 * TODO:
 * - GPIO interrupt support
 * - Pin pad configuration (pull up/down, strength)
 */

#include <linux/gpio/driver.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/mod_devicetable.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>

#include <linux/pinctrl/machine.h>
#include <linux/pinctrl/pinconf.h>
#include <linux/pinctrl/pinconf-generic.h>
#include <linux/pinctrl/pinctrl.h>
#include <linux/pinctrl/pinmux.h>

#include "pinctrl-utils.h"

#define DRIVER_NAME     "pinctrl-digicolor"

#define GP_CLIENTSEL(clct)      ((clct)*8 + 0x20)
#define GP_DRIVE0(clct)         (GP_CLIENTSEL(clct) + 2)
#define GP_OUTPUT0(clct)        (GP_CLIENTSEL(clct) + 3)
#define GP_INPUT(clct)          (GP_CLIENTSEL(clct) + 6)

#define PIN_COLLECTIONS         ('R' - 'A' + 1)
#define PINS_PER_COLLECTION     8
#define PINS_COUNT              (PIN_COLLECTIONS * PINS_PER_COLLECTION)

struct dc_pinmap {
        void __iomem            *regs;
        struct device           *dev;
        struct pinctrl_dev      *pctl;

        struct pinctrl_desc     *desc;
        const char              *pin_names[PINS_COUNT];

        struct gpio_chip        chip;
        spinlock_t              lock;
};

static int dc_get_groups_count(struct pinctrl_dev *pctldev)
{
        return PINS_COUNT;
}

static const char *dc_get_group_name(struct pinctrl_dev *pctldev,
                                     unsigned selector)
{
        struct dc_pinmap *pmap = pinctrl_dev_get_drvdata(pctldev);

        /* Exactly one group per pin */
        return pmap->desc->pins[selector].name;
}

static int dc_get_group_pins(struct pinctrl_dev *pctldev, unsigned selector,
                             const unsigned **pins,
                             unsigned *num_pins)
{
        struct dc_pinmap *pmap = pinctrl_dev_get_drvdata(pctldev);

        *pins = &pmap->desc->pins[selector].number;
        *num_pins = 1;

        return 0;
}

static const struct pinctrl_ops dc_pinctrl_ops = {
        .get_groups_count       = dc_get_groups_count,
        .get_group_name         = dc_get_group_name,
        .get_group_pins         = dc_get_group_pins,
        .dt_node_to_map         = pinconf_generic_dt_node_to_map_pin,
        .dt_free_map            = pinctrl_utils_free_map,
};

static const char *const dc_functions[] = {
        "gpio",
        "client_a",
        "client_b",
        "client_c",
};

static int dc_get_functions_count(struct pinctrl_dev *pctldev)
{
        return ARRAY_SIZE(dc_functions);
}

static const char *dc_get_fname(struct pinctrl_dev *pctldev, unsigned selector)
{
        return dc_functions[selector];
}

static int dc_get_groups(struct pinctrl_dev *pctldev, unsigned selector,
                         const char * const **groups,
                         unsigned * const num_groups)
{
        struct dc_pinmap *pmap = pinctrl_dev_get_drvdata(pctldev);

        *groups = pmap->pin_names;
        *num_groups = PINS_COUNT;

        return 0;
}

static void dc_client_sel(int pin_num, int *reg, int *bit)
{
        *bit = (pin_num % PINS_PER_COLLECTION) * 2;
        *reg = GP_CLIENTSEL(pin_num/PINS_PER_COLLECTION);

        if (*bit >= PINS_PER_COLLECTION) {
                *bit -= PINS_PER_COLLECTION;
                *reg += 1;
        }
}

static int dc_set_mux(struct pinctrl_dev *pctldev, unsigned selector,
                      unsigned group)
{
        struct dc_pinmap *pmap = pinctrl_dev_get_drvdata(pctldev);
        int bit_off, reg_off;
        u8 reg;

        dc_client_sel(group, &reg_off, &bit_off);

        reg = readb_relaxed(pmap->regs + reg_off);
        reg &= ~(3 << bit_off);
        reg |= (selector << bit_off);
        writeb_relaxed(reg, pmap->regs + reg_off);

        return 0;
}

static int dc_pmx_request_gpio(struct pinctrl_dev *pcdev,
                               struct pinctrl_gpio_range *range,
                               unsigned offset)
{
        struct dc_pinmap *pmap = pinctrl_dev_get_drvdata(pcdev);
        int bit_off, reg_off;
        u8 reg;

        dc_client_sel(offset, &reg_off, &bit_off);

        reg = readb_relaxed(pmap->regs + reg_off);
        if ((reg & (3 << bit_off)) != 0)
                return -EBUSY;

        return 0;
}

static const struct pinmux_ops dc_pmxops = {
        .get_functions_count    = dc_get_functions_count,
        .get_function_name      = dc_get_fname,
        .get_function_groups    = dc_get_groups,
        .set_mux                = dc_set_mux,
        .gpio_request_enable    = dc_pmx_request_gpio,
};

static int dc_gpio_direction_input(struct gpio_chip *chip, unsigned gpio)
{
        struct dc_pinmap *pmap = gpiochip_get_data(chip);
        int reg_off = GP_DRIVE0(gpio/PINS_PER_COLLECTION);
        int bit_off = gpio % PINS_PER_COLLECTION;
        u8 drive;
        unsigned long flags;

        spin_lock_irqsave(&pmap->lock, flags);
        drive = readb_relaxed(pmap->regs + reg_off);
        drive &= ~BIT(bit_off);
        writeb_relaxed(drive, pmap->regs + reg_off);
        spin_unlock_irqrestore(&pmap->lock, flags);

        return 0;
}

static int dc_gpio_set(struct gpio_chip *chip, unsigned int gpio, int value);

static int dc_gpio_direction_output(struct gpio_chip *chip, unsigned gpio,
                                    int value)
{
        struct dc_pinmap *pmap = gpiochip_get_data(chip);
        int reg_off = GP_DRIVE0(gpio/PINS_PER_COLLECTION);
        int bit_off = gpio % PINS_PER_COLLECTION;
        u8 drive;
        unsigned long flags;

        dc_gpio_set(chip, gpio, value);

        spin_lock_irqsave(&pmap->lock, flags);
        drive = readb_relaxed(pmap->regs + reg_off);
        drive |= BIT(bit_off);
        writeb_relaxed(drive, pmap->regs + reg_off);
        spin_unlock_irqrestore(&pmap->lock, flags);

        return 0;
}

static int dc_gpio_get(struct gpio_chip *chip, unsigned gpio)
{
        struct dc_pinmap *pmap = gpiochip_get_data(chip);
        int reg_off = GP_INPUT(gpio/PINS_PER_COLLECTION);
        int bit_off = gpio % PINS_PER_COLLECTION;
        u8 input;

        input = readb_relaxed(pmap->regs + reg_off);

        return !!(input & BIT(bit_off));
}

static int dc_gpio_set(struct gpio_chip *chip, unsigned int gpio, int value)
{
        struct dc_pinmap *pmap = gpiochip_get_data(chip);
        int reg_off = GP_OUTPUT0(gpio/PINS_PER_COLLECTION);
        int bit_off = gpio % PINS_PER_COLLECTION;
        u8 output;
        unsigned long flags;

        spin_lock_irqsave(&pmap->lock, flags);
        output = readb_relaxed(pmap->regs + reg_off);
        if (value)
                output |= BIT(bit_off);
        else
                output &= ~BIT(bit_off);
        writeb_relaxed(output, pmap->regs + reg_off);
        spin_unlock_irqrestore(&pmap->lock, flags);

        return 0;
}

static int dc_gpiochip_add(struct dc_pinmap *pmap)
{
        struct gpio_chip *chip = &pmap->chip;
        int ret;

        chip->label             = DRIVER_NAME;
        chip->parent            = pmap->dev;
        chip->request           = gpiochip_generic_request;
        chip->free              = gpiochip_generic_free;
        chip->direction_input   = dc_gpio_direction_input;
        chip->direction_output  = dc_gpio_direction_output;
        chip->get               = dc_gpio_get;
        chip->set               = dc_gpio_set;
        chip->base              = -1;
        chip->ngpio             = PINS_COUNT;

        spin_lock_init(&pmap->lock);

        ret = gpiochip_add_data(chip, pmap);
        if (ret < 0)
                return ret;

        ret = gpiochip_add_pin_range(chip, dev_name(pmap->dev), 0, 0,
                                     PINS_COUNT);
        if (ret < 0) {
                gpiochip_remove(chip);
                return ret;
        }

        return 0;
}

static int dc_pinctrl_probe(struct platform_device *pdev)
{
        struct dc_pinmap *pmap;
        struct pinctrl_pin_desc *pins;
        struct pinctrl_desc *pctl_desc;
        char *pin_names;
        int name_len = strlen("GP_xx") + 1;
        int i, j;

        pmap = devm_kzalloc(&pdev->dev, sizeof(*pmap), GFP_KERNEL);
        if (!pmap)
                return -ENOMEM;

        pmap->regs = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(pmap->regs))
                return PTR_ERR(pmap->regs);

        pins = devm_kcalloc(&pdev->dev, PINS_COUNT, sizeof(*pins),
                            GFP_KERNEL);
        if (!pins)
                return -ENOMEM;
        pin_names = devm_kcalloc(&pdev->dev, PINS_COUNT, name_len,
                                 GFP_KERNEL);
        if (!pin_names)
                return -ENOMEM;

        for (i = 0; i < PIN_COLLECTIONS; i++) {
                for (j = 0; j < PINS_PER_COLLECTION; j++) {
                        int pin_id = i*PINS_PER_COLLECTION + j;
                        char *name = &pin_names[pin_id * name_len];

                        snprintf(name, name_len, "GP_%c%c", 'A'+i, '0'+j);

                        pins[pin_id].number = pin_id;
                        pins[pin_id].name = name;
                        pmap->pin_names[pin_id] = name;
                }
        }

        pctl_desc = devm_kzalloc(&pdev->dev, sizeof(*pctl_desc), GFP_KERNEL);
        if (!pctl_desc)
                return -ENOMEM;

        pctl_desc->name = DRIVER_NAME,
        pctl_desc->owner = THIS_MODULE,
        pctl_desc->pctlops = &dc_pinctrl_ops,
        pctl_desc->pmxops = &dc_pmxops,
        pctl_desc->npins = PINS_COUNT;
        pctl_desc->pins = pins;
        pmap->desc = pctl_desc;

        pmap->dev = &pdev->dev;

        pmap->pctl = devm_pinctrl_register(&pdev->dev, pctl_desc, pmap);
        if (IS_ERR(pmap->pctl)) {
                dev_err(&pdev->dev, "pinctrl driver registration failed\n");
                return PTR_ERR(pmap->pctl);
        }

        return dc_gpiochip_add(pmap);
}

static const struct of_device_id dc_pinctrl_ids[] = {
        { .compatible = "cnxt,cx92755-pinctrl" },
        { /* sentinel */ }
};

static struct platform_driver dc_pinctrl_driver = {
        .driver = {
                .name = DRIVER_NAME,
                .of_match_table = dc_pinctrl_ids,
                .suppress_bind_attrs = true,
        },
        .probe = dc_pinctrl_probe,
};
builtin_platform_driver(dc_pinctrl_driver);