// SPDX-License-Identifier: GPL-2.0
/*
 * Dummy driver for Intel's Image Signal Processor found on Bay Trail
 * and Cherry Trail devices. The sole purpose of this driver is to allow
 * the ISP to be put in D3.
 *
 * Copyright (C) 2018 Hans de Goede <hdegoede@redhat.com>
 *
 * Based on various non upstream patches for ISP support:
 * Copyright (C) 2010-2017 Intel Corporation. All rights reserved.
 * Copyright (c) 2010 Silicon Hive www.siliconhive.com.
 */

#include <linux/delay.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/pci.h>
#include <linux/pm_runtime.h>
#include <asm/iosf_mbi.h>

/* PCI configuration regs */
#define PCI_INTERRUPT_CTRL              0x9c

#define PCI_CSI_CONTROL                 0xe8
#define PCI_CSI_CONTROL_PORTS_OFF_MASK  0x7

/* IOSF BT_MBI_UNIT_PMC regs */
#define ISPSSPM0                        0x39
#define ISPSSPM0_ISPSSC_OFFSET          0
#define ISPSSPM0_ISPSSC_MASK            0x00000003
#define ISPSSPM0_ISPSSS_OFFSET          24
#define ISPSSPM0_ISPSSS_MASK            0x03000000
#define ISPSSPM0_IUNIT_POWER_ON         0x0
#define ISPSSPM0_IUNIT_POWER_OFF        0x3

static int isp_set_power(struct pci_dev *dev, bool enable)
{
        unsigned long timeout;
        u32 val = enable ? ISPSSPM0_IUNIT_POWER_ON : ISPSSPM0_IUNIT_POWER_OFF;

        /* Write to ISPSSPM0 bit[1:0] to power on/off the IUNIT */
        iosf_mbi_modify(BT_MBI_UNIT_PMC, MBI_REG_READ, ISPSSPM0,
                        val, ISPSSPM0_ISPSSC_MASK);

        /*
         * There should be no IUNIT access while power-down is
         * in progress. HW sighting: 4567865.
         * Wait up to 50 ms for the IUNIT to shut down.
         * And we do the same for power on.
         */
        timeout = jiffies + msecs_to_jiffies(50);
        do {
                u32 tmp;

                /* Wait until ISPSSPM0 bit[25:24] shows the right value */
                iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, ISPSSPM0, &tmp);
                tmp = (tmp & ISPSSPM0_ISPSSS_MASK) >> ISPSSPM0_ISPSSS_OFFSET;
                if (tmp == val)
                        return 0;

                usleep_range(1000, 2000);
        } while (time_before(jiffies, timeout));

        dev_err(&dev->dev, "IUNIT power-%s timeout.\n", enable ? "on" : "off");
        return -EBUSY;
}

static int isp_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
        pm_runtime_allow(&dev->dev);
        pm_runtime_put_sync_suspend(&dev->dev);

        return 0;
}

static void isp_remove(struct pci_dev *dev)
{
        pm_runtime_get_sync(&dev->dev);
        pm_runtime_forbid(&dev->dev);
}

static int isp_pci_suspend(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        u32 val;

        pci_write_config_dword(pdev, PCI_INTERRUPT_CTRL, 0);

        /*
         * MRFLD IUNIT DPHY is located in an always-power-on island
         * MRFLD HW design need all CSI ports are disabled before
         * powering down the IUNIT.
         */
        pci_read_config_dword(pdev, PCI_CSI_CONTROL, &val);
        val |= PCI_CSI_CONTROL_PORTS_OFF_MASK;
        pci_write_config_dword(pdev, PCI_CSI_CONTROL, val);

        /*
         * We lose config space access when punit power gates
         * the ISP. Can't use pci_set_power_state() because
         * pmcsr won't actually change when we write to it.
         */
        pci_save_state(pdev);
        pdev->current_state = PCI_D3cold;
        isp_set_power(pdev, false);

        return 0;
}

static int isp_pci_resume(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);

        isp_set_power(pdev, true);
        pdev->current_state = PCI_D0;
        pci_restore_state(pdev);

        return 0;
}

static UNIVERSAL_DEV_PM_OPS(isp_pm_ops, isp_pci_suspend,
                            isp_pci_resume, NULL);

static const struct pci_device_id isp_id_table[] = {
        { PCI_VDEVICE(INTEL, 0x0f38), },
        { PCI_VDEVICE(INTEL, 0x22b8), },
        { 0, }
};
MODULE_DEVICE_TABLE(pci, isp_id_table);

static struct pci_driver isp_pci_driver = {
        .name = "intel_atomisp2_pm",
        .id_table = isp_id_table,
        .probe = isp_probe,
        .remove = isp_remove,
        .driver.pm = &isp_pm_ops,
};

module_pci_driver(isp_pci_driver);

MODULE_DESCRIPTION("Intel AtomISP2 dummy / power-management drv (for suspend)");
MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
MODULE_LICENSE("GPL v2");