// SPDX-License-Identifier: GPL-2.0+
/*
 * Driver for the external-charger IRQ pass-through function of the
 * Intel Bay Trail Crystal Cove PMIC.
 *
 * Note this is NOT a power_supply class driver, it just deals with IRQ
 * pass-through, this requires a separate driver because the PMIC's
 * level 2 interrupt for this must be explicitly acked.
 */

#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/mfd/intel_soc_pmic.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>

#define CHGRIRQ_REG                                     0x0a
#define MCHGRIRQ_REG                                    0x17

struct crystal_cove_charger_data {
        struct mutex buslock; /* irq_bus_lock */
        struct irq_chip irqchip;
        struct regmap *regmap;
        struct irq_domain *irq_domain;
        int irq;
        int charger_irq;
        u8 mask;
        u8 new_mask;
};

static irqreturn_t crystal_cove_charger_irq(int irq, void *data)
{
        struct crystal_cove_charger_data *charger = data;

        /* No need to read CHGRIRQ_REG as there is only 1 IRQ */
        handle_nested_irq(charger->charger_irq);

        /* Ack CHGRIRQ 0 */
        regmap_write(charger->regmap, CHGRIRQ_REG, BIT(0));

        return IRQ_HANDLED;
}

static void crystal_cove_charger_irq_bus_lock(struct irq_data *data)
{
        struct crystal_cove_charger_data *charger = irq_data_get_irq_chip_data(data);

        mutex_lock(&charger->buslock);
}

static void crystal_cove_charger_irq_bus_sync_unlock(struct irq_data *data)
{
        struct crystal_cove_charger_data *charger = irq_data_get_irq_chip_data(data);

        if (charger->mask != charger->new_mask) {
                regmap_write(charger->regmap, MCHGRIRQ_REG, charger->new_mask);
                charger->mask = charger->new_mask;
        }

        mutex_unlock(&charger->buslock);
}

static void crystal_cove_charger_irq_unmask(struct irq_data *data)
{
        struct crystal_cove_charger_data *charger = irq_data_get_irq_chip_data(data);

        charger->new_mask &= ~BIT(data->hwirq);
}

static void crystal_cove_charger_irq_mask(struct irq_data *data)
{
        struct crystal_cove_charger_data *charger = irq_data_get_irq_chip_data(data);

        charger->new_mask |= BIT(data->hwirq);
}

static void crystal_cove_charger_rm_irq_domain(void *data)
{
        struct crystal_cove_charger_data *charger = data;

        irq_domain_remove(charger->irq_domain);
}

static int crystal_cove_charger_probe(struct platform_device *pdev)
{
        struct intel_soc_pmic *pmic = dev_get_drvdata(pdev->dev.parent);
        struct crystal_cove_charger_data *charger;
        int ret;

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

        charger->regmap = pmic->regmap;
        mutex_init(&charger->buslock);

        charger->irq = platform_get_irq(pdev, 0);
        if (charger->irq < 0)
                return charger->irq;

        charger->irq_domain = irq_domain_create_linear(dev_fwnode(pdev->dev.parent), 1,
                                                       &irq_domain_simple_ops, NULL);
        if (!charger->irq_domain)
                return -ENOMEM;

        /* Distuingish IRQ domain from others sharing (MFD) the same fwnode */
        irq_domain_update_bus_token(charger->irq_domain, DOMAIN_BUS_WAKEUP);

        ret = devm_add_action_or_reset(&pdev->dev, crystal_cove_charger_rm_irq_domain, charger);
        if (ret)
                return ret;

        charger->charger_irq = irq_create_mapping(charger->irq_domain, 0);
        if (!charger->charger_irq)
                return -ENOMEM;

        charger->irqchip.name = KBUILD_MODNAME;
        charger->irqchip.irq_unmask = crystal_cove_charger_irq_unmask;
        charger->irqchip.irq_mask = crystal_cove_charger_irq_mask;
        charger->irqchip.irq_bus_lock = crystal_cove_charger_irq_bus_lock;
        charger->irqchip.irq_bus_sync_unlock = crystal_cove_charger_irq_bus_sync_unlock;

        irq_set_chip_data(charger->charger_irq, charger);
        irq_set_chip_and_handler(charger->charger_irq, &charger->irqchip, handle_simple_irq);
        irq_set_nested_thread(charger->charger_irq, true);
        irq_set_noprobe(charger->charger_irq);

        /* Mask the single 2nd level IRQ before enabling the 1st level IRQ */
        charger->mask = charger->new_mask = BIT(0);
        regmap_write(charger->regmap, MCHGRIRQ_REG, charger->mask);

        ret = devm_request_threaded_irq(&pdev->dev, charger->irq, NULL,
                                        crystal_cove_charger_irq,
                                        IRQF_ONESHOT, KBUILD_MODNAME, charger);
        if (ret)
                return dev_err_probe(&pdev->dev, ret, "requesting irq\n");

        return 0;
}

static struct platform_driver crystal_cove_charger_driver = {
        .probe = crystal_cove_charger_probe,
        .driver = {
                .name = "crystal_cove_charger",
        },
};
module_platform_driver(crystal_cove_charger_driver);

MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com");
MODULE_DESCRIPTION("Intel Bay Trail Crystal Cove external charger IRQ pass-through");
MODULE_LICENSE("GPL");