root/drivers/usb/misc/brcmstb-usb-pinmap.c
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2020, Broadcom */

#include <linux/init.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/device.h>
#include <linux/of.h>
#include <linux/kernel.h>
#include <linux/kdebug.h>
#include <linux/gpio/consumer.h>

struct out_pin {
        u32 enable_mask;
        u32 value_mask;
        u32 changed_mask;
        u32 clr_changed_mask;
        struct gpio_desc *gpiod;
        const char *name;
};

struct in_pin {
        u32 enable_mask;
        u32 value_mask;
        struct gpio_desc *gpiod;
        const char *name;
        struct brcmstb_usb_pinmap_data *pdata;
};

struct brcmstb_usb_pinmap_data {
        void __iomem *regs;
        int in_count;
        struct in_pin *in_pins;
        int out_count;
        struct out_pin *out_pins;
};


static void pinmap_set(void __iomem *reg, u32 mask)
{
        u32 val;

        val = readl(reg);
        val |= mask;
        writel(val, reg);
}

static void pinmap_unset(void __iomem *reg, u32 mask)
{
        u32 val;

        val = readl(reg);
        val &= ~mask;
        writel(val, reg);
}

static void sync_in_pin(struct in_pin *pin)
{
        u32 val;

        val = gpiod_get_value(pin->gpiod);
        if (val)
                pinmap_set(pin->pdata->regs, pin->value_mask);
        else
                pinmap_unset(pin->pdata->regs, pin->value_mask);
}

/*
 * Interrupt from override register, propagate from override bit
 * to GPIO.
 */
static irqreturn_t brcmstb_usb_pinmap_ovr_isr(int irq, void *dev_id)
{
        struct brcmstb_usb_pinmap_data *pdata = dev_id;
        struct out_pin *pout;
        u32 val;
        u32 bit;
        int x;

        pr_debug("%s: reg: 0x%x\n", __func__, readl(pdata->regs));
        pout = pdata->out_pins;
        for (x = 0; x < pdata->out_count; x++) {
                val = readl(pdata->regs);
                if (val & pout->changed_mask) {
                        pinmap_set(pdata->regs, pout->clr_changed_mask);
                        pinmap_unset(pdata->regs, pout->clr_changed_mask);
                        bit = val & pout->value_mask;
                        gpiod_set_value(pout->gpiod, bit ? 1 : 0);
                        pr_debug("%s: %s bit changed state to %d\n",
                                 __func__, pout->name, bit ? 1 : 0);
                }
        }
        return IRQ_HANDLED;
}

/*
 * Interrupt from GPIO, propagate from GPIO to override bit.
 */
static irqreturn_t brcmstb_usb_pinmap_gpio_isr(int irq, void *dev_id)
{
        struct in_pin *pin = dev_id;

        pr_debug("%s: %s pin changed state\n", __func__, pin->name);
        sync_in_pin(pin);
        return IRQ_HANDLED;
}


static void get_pin_counts(struct device_node *dn, int *in_count,
                           int *out_count)
{
        int in;
        int out;

        *in_count = 0;
        *out_count = 0;
        in = of_property_count_strings(dn, "brcm,in-functions");
        if (in < 0)
                return;
        out = of_property_count_strings(dn, "brcm,out-functions");
        if (out < 0)
                return;
        *in_count = in;
        *out_count = out;
}

static int parse_pins(struct device *dev, struct device_node *dn,
                      struct brcmstb_usb_pinmap_data *pdata)
{
        struct out_pin *pout;
        struct in_pin *pin;
        int index;
        int res;
        int x;

        pin = pdata->in_pins;
        for (x = 0, index = 0; x < pdata->in_count; x++) {
                pin->gpiod = devm_gpiod_get_index(dev, "in", x, GPIOD_IN);
                if (IS_ERR(pin->gpiod)) {
                        dev_err(dev, "Error getting gpio %s\n", pin->name);
                        return PTR_ERR(pin->gpiod);

                }
                res = of_property_read_string_index(dn, "brcm,in-functions", x,
                                                    &pin->name);
                if (res < 0) {
                        dev_err(dev, "Error getting brcm,in-functions for %s\n",
                                pin->name);
                        return res;
                }
                res = of_property_read_u32_index(dn, "brcm,in-masks", index++,
                                                 &pin->enable_mask);
                if (res < 0) {
                        dev_err(dev, "Error getting 1st brcm,in-masks for %s\n",
                                pin->name);
                        return res;
                }
                res = of_property_read_u32_index(dn, "brcm,in-masks", index++,
                                                 &pin->value_mask);
                if (res < 0) {
                        dev_err(dev, "Error getting 2nd brcm,in-masks for %s\n",
                                pin->name);
                        return res;
                }
                pin->pdata = pdata;
                pin++;
        }
        pout = pdata->out_pins;
        for (x = 0, index = 0; x < pdata->out_count; x++) {
                pout->gpiod = devm_gpiod_get_index(dev, "out", x,
                                                   GPIOD_OUT_HIGH);
                if (IS_ERR(pout->gpiod)) {
                        dev_err(dev, "Error getting gpio %s\n", pin->name);
                        return PTR_ERR(pout->gpiod);
                }
                res = of_property_read_string_index(dn, "brcm,out-functions", x,
                                                    &pout->name);
                if (res < 0) {
                        dev_err(dev, "Error getting brcm,out-functions for %s\n",
                                pout->name);
                        return res;
                }
                res = of_property_read_u32_index(dn, "brcm,out-masks", index++,
                                                 &pout->enable_mask);
                if (res < 0) {
                        dev_err(dev, "Error getting 1st brcm,out-masks for %s\n",
                                pout->name);
                        return res;
                }
                res = of_property_read_u32_index(dn, "brcm,out-masks", index++,
                                                 &pout->value_mask);
                if (res < 0) {
                        dev_err(dev, "Error getting 2nd brcm,out-masks for %s\n",
                                pout->name);
                        return res;
                }
                res = of_property_read_u32_index(dn, "brcm,out-masks", index++,
                                                 &pout->changed_mask);
                if (res < 0) {
                        dev_err(dev, "Error getting 3rd brcm,out-masks for %s\n",
                                pout->name);
                        return res;
                }
                res = of_property_read_u32_index(dn, "brcm,out-masks", index++,
                                                 &pout->clr_changed_mask);
                if (res < 0) {
                        dev_err(dev, "Error getting 4th out-masks for %s\n",
                                pout->name);
                        return res;
                }
                pout++;
        }
        return 0;
}

static void sync_all_pins(struct brcmstb_usb_pinmap_data *pdata)
{
        struct out_pin *pout;
        struct in_pin *pin;
        int val;
        int x;

        /*
         * Enable the override, clear any changed condition and
         * propagate the state to the GPIO for all out pins.
         */
        pout = pdata->out_pins;
        for (x = 0; x < pdata->out_count; x++) {
                pinmap_set(pdata->regs, pout->enable_mask);
                pinmap_set(pdata->regs, pout->clr_changed_mask);
                pinmap_unset(pdata->regs, pout->clr_changed_mask);
                val = readl(pdata->regs) & pout->value_mask;
                gpiod_set_value(pout->gpiod, val ? 1 : 0);
                pout++;
        }

        /* sync and enable all in pins. */
        pin = pdata->in_pins;
        for (x = 0; x < pdata->in_count; x++) {
                sync_in_pin(pin);
                pinmap_set(pdata->regs, pin->enable_mask);
                pin++;
        }
}

static int __init brcmstb_usb_pinmap_probe(struct platform_device *pdev)
{
        struct device_node *dn = pdev->dev.of_node;
        struct brcmstb_usb_pinmap_data *pdata;
        struct in_pin *pin;
        struct resource *r;
        int out_count;
        int in_count;
        int err;
        int irq;
        int x;

        get_pin_counts(dn, &in_count, &out_count);
        if ((in_count + out_count) == 0)
                return -EINVAL;

        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!r)
                return -EINVAL;

        pdata = devm_kzalloc(&pdev->dev,
                             sizeof(*pdata) +
                             (sizeof(struct in_pin) * in_count) +
                             (sizeof(struct out_pin) * out_count), GFP_KERNEL);
        if (!pdata)
                return -ENOMEM;

        pdata->in_count = in_count;
        pdata->out_count = out_count;
        pdata->in_pins = (struct in_pin *)(pdata + 1);
        pdata->out_pins = (struct out_pin *)(pdata->in_pins + in_count);

        pdata->regs = devm_ioremap(&pdev->dev, r->start, resource_size(r));
        if (!pdata->regs)
                return -ENOMEM;
        platform_set_drvdata(pdev, pdata);

        err = parse_pins(&pdev->dev, dn, pdata);
        if (err)
                return err;

        sync_all_pins(pdata);

        if (out_count) {

                /* Enable interrupt for out pins */
                irq = platform_get_irq(pdev, 0);
                if (irq < 0)
                        return irq;
                err = devm_request_irq(&pdev->dev, irq,
                                       brcmstb_usb_pinmap_ovr_isr,
                                       IRQF_TRIGGER_RISING,
                                       pdev->name, pdata);
                if (err < 0) {
                        dev_err(&pdev->dev, "Error requesting IRQ\n");
                        return err;
                }
        }

        for (x = 0, pin = pdata->in_pins; x < pdata->in_count; x++, pin++) {
                irq = gpiod_to_irq(pin->gpiod);
                if (irq < 0) {
                        dev_err(&pdev->dev, "Error getting IRQ for %s pin\n",
                                pin->name);
                        return irq;
                }
                err = devm_request_irq(&pdev->dev, irq,
                                       brcmstb_usb_pinmap_gpio_isr,
                                       IRQF_SHARED | IRQF_TRIGGER_RISING |
                                       IRQF_TRIGGER_FALLING,
                                       pdev->name, pin);
                if (err < 0) {
                        dev_err(&pdev->dev, "Error requesting IRQ for %s pin\n",
                                pin->name);
                        return err;
                }
        }

        dev_dbg(&pdev->dev, "Driver probe succeeded\n");
        dev_dbg(&pdev->dev, "In pin count: %d, out pin count: %d\n",
                pdata->in_count, pdata->out_count);
        return 0;
}


static const struct of_device_id brcmstb_usb_pinmap_of_match[] = {
        { .compatible = "brcm,usb-pinmap" },
        { },
};
MODULE_DEVICE_TABLE(of, brcmstb_usb_pinmap_of_match);

static struct platform_driver brcmstb_usb_pinmap_driver = {
        .driver = {
                .name   = "brcm-usb-pinmap",
                .of_match_table = brcmstb_usb_pinmap_of_match,
        },
};

static int __init brcmstb_usb_pinmap_init(void)
{
        return platform_driver_probe(&brcmstb_usb_pinmap_driver,
                                     brcmstb_usb_pinmap_probe);
}

module_init(brcmstb_usb_pinmap_init);
MODULE_AUTHOR("Al Cooper <alcooperx@gmail.com>");
MODULE_DESCRIPTION("Broadcom USB Pinmap Driver");
MODULE_LICENSE("GPL");