// SPDX-License-Identifier: GPL-2.0
/*
 * Dummy driver for Intel's Image Signal Processor found on Bay 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_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
	unsigned long timeout;
	u32 val;

	pci_write_config_dword(dev, 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(dev, PCI_CSI_CONTROL, &val);
	val |= PCI_CSI_CONTROL_PORTS_OFF_MASK;
	pci_write_config_dword(dev, PCI_CSI_CONTROL, val);

	/* Write 0x3 to ISPSSPM0 bit[1:0] to power off the IUNIT */
	iosf_mbi_modify(BT_MBI_UNIT_PMC, MBI_REG_READ, ISPSSPM0,
			ISPSSPM0_IUNIT_POWER_OFF, 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.
	 */
	timeout = jiffies + msecs_to_jiffies(50);
	while (1) {
		/* Wait until ISPSSPM0 bit[25:24] shows 0x3 */
		iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, ISPSSPM0, &val);
		val = (val & ISPSSPM0_ISPSSS_MASK) >> ISPSSPM0_ISPSSS_OFFSET;
		if (val == ISPSSPM0_IUNIT_POWER_OFF)
			break;

		if (time_after(jiffies, timeout)) {
			dev_err(&dev->dev, "IUNIT power-off timeout.\n");
			return -EBUSY;
		}
		usleep_range(1000, 2000);
	}

	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)
{
	return 0;
}

static int isp_pci_resume(struct device *dev)
{
	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, 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");