// SPDX-License-Identifier: GPL-2.0-only
/*
 * Intel MID Power Management Unit (PWRMU) device driver
 *
 * Copyright (C) 2016, Intel Corporation
 *
 * Author: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
 *
 * Intel MID Power Management Unit device driver handles the South Complex PCI
 * devices such as GPDMA, SPI, I2C, PWM, and so on. By default PCI core
 * modifies bits in PMCSR register in the PCI configuration space. This is not
 * enough on some SoCs like Intel Tangier. In such case PCI core sets a new
 * power state of the device in question through a PM hook registered in struct
 * pci_platform_pm_ops (see drivers/pci/pci-mid.c).
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/mutex.h>
#include <linux/pci.h>

#include <asm/intel-mid.h>

/* Registers */
#define PM_STS                  0x00
#define PM_CMD                  0x04
#define PM_ICS                  0x08
#define PM_WKC(x)               (0x10 + (x) * 4)
#define PM_WKS(x)               (0x18 + (x) * 4)
#define PM_SSC(x)               (0x20 + (x) * 4)
#define PM_SSS(x)               (0x30 + (x) * 4)

/* Bits in PM_STS */
#define PM_STS_BUSY             (1 << 8)

/* Bits in PM_CMD */
#define PM_CMD_CMD(x)           ((x) << 0)
#define PM_CMD_IOC              (1 << 8)
#define PM_CMD_CM_NOP           (0 << 9)
#define PM_CMD_CM_IMMEDIATE     (1 << 9)
#define PM_CMD_CM_DELAY         (2 << 9)
#define PM_CMD_CM_TRIGGER       (3 << 9)

/* System states */
#define PM_CMD_SYS_STATE_S5     (5 << 16)

/* Trigger variants */
#define PM_CMD_CFG_TRIGGER_NC   (3 << 19)

/* Message to wait for TRIGGER_NC case */
#define TRIGGER_NC_MSG_2        (2 << 22)

/* List of commands */
#define CMD_SET_CFG             0x01

/* Bits in PM_ICS */
#define PM_ICS_INT_STATUS(x)    ((x) & 0xff)
#define PM_ICS_IE               (1 << 8)
#define PM_ICS_IP               (1 << 9)
#define PM_ICS_SW_INT_STS       (1 << 10)

/* List of interrupts */
#define INT_INVALID             0
#define INT_CMD_COMPLETE        1
#define INT_CMD_ERR             2
#define INT_WAKE_EVENT          3
#define INT_LSS_POWER_ERR       4
#define INT_S0iX_MSG_ERR        5
#define INT_NO_C6               6
#define INT_TRIGGER_ERR         7
#define INT_INACTIVITY          8

/* South Complex devices */
#define LSS_MAX_SHARED_DEVS     4
#define LSS_MAX_DEVS            64

#define LSS_WS_BITS             1       /* wake state width */
#define LSS_PWS_BITS            2       /* power state width */

/* Supported device IDs */
#define PCI_DEVICE_ID_PENWELL   0x0828
#define PCI_DEVICE_ID_TANGIER   0x11a1

struct mid_pwr_dev {
        struct pci_dev *pdev;
        pci_power_t state;
};

struct mid_pwr {
        struct device *dev;
        void __iomem *regs;
        int irq;
        bool available;

        struct mutex lock;
        struct mid_pwr_dev lss[LSS_MAX_DEVS][LSS_MAX_SHARED_DEVS];
};

static struct mid_pwr *midpwr;

static u32 mid_pwr_get_state(struct mid_pwr *pwr, int reg)
{
        return readl(pwr->regs + PM_SSS(reg));
}

static void mid_pwr_set_state(struct mid_pwr *pwr, int reg, u32 value)
{
        writel(value, pwr->regs + PM_SSC(reg));
}

static void mid_pwr_set_wake(struct mid_pwr *pwr, int reg, u32 value)
{
        writel(value, pwr->regs + PM_WKC(reg));
}

static void mid_pwr_interrupt_disable(struct mid_pwr *pwr)
{
        writel(~PM_ICS_IE, pwr->regs + PM_ICS);
}

static bool mid_pwr_is_busy(struct mid_pwr *pwr)
{
        return !!(readl(pwr->regs + PM_STS) & PM_STS_BUSY);
}

/* Wait 500ms that the latest PWRMU command finished */
static int mid_pwr_wait(struct mid_pwr *pwr)
{
        unsigned int count = 500000;
        bool busy;

        do {
                busy = mid_pwr_is_busy(pwr);
                if (!busy)
                        return 0;
                udelay(1);
        } while (--count);

        return -EBUSY;
}

static int mid_pwr_wait_for_cmd(struct mid_pwr *pwr, u8 cmd)
{
        writel(PM_CMD_CMD(cmd) | PM_CMD_CM_IMMEDIATE, pwr->regs + PM_CMD);
        return mid_pwr_wait(pwr);
}

static int __update_power_state(struct mid_pwr *pwr, int reg, int bit, int new)
{
        int curstate;
        u32 power;
        int ret;

        /* Check if the device is already in desired state */
        power = mid_pwr_get_state(pwr, reg);
        curstate = (power >> bit) & 3;
        if (curstate == new)
                return 0;

        /* Update the power state */
        mid_pwr_set_state(pwr, reg, (power & ~(3 << bit)) | (new << bit));

        /* Send command to SCU */
        ret = mid_pwr_wait_for_cmd(pwr, CMD_SET_CFG);
        if (ret)
                return ret;

        /* Check if the device is already in desired state */
        power = mid_pwr_get_state(pwr, reg);
        curstate = (power >> bit) & 3;
        if (curstate != new)
                return -EAGAIN;

        return 0;
}

static pci_power_t __find_weakest_power_state(struct mid_pwr_dev *lss,
                                              struct pci_dev *pdev,
                                              pci_power_t state)
{
        pci_power_t weakest = PCI_D3hot;
        unsigned int j;

        /* Find device in cache or first free cell */
        for (j = 0; j < LSS_MAX_SHARED_DEVS; j++) {
                if (lss[j].pdev == pdev || !lss[j].pdev)
                        break;
        }

        /* Store the desired state in cache */
        if (j < LSS_MAX_SHARED_DEVS) {
                lss[j].pdev = pdev;
                lss[j].state = state;
        } else {
                dev_WARN(&pdev->dev, "No room for device in PWRMU LSS cache\n");
                weakest = state;
        }

        /* Find the power state we may use */
        for (j = 0; j < LSS_MAX_SHARED_DEVS; j++) {
                if (lss[j].state < weakest)
                        weakest = lss[j].state;
        }

        return weakest;
}

static int __set_power_state(struct mid_pwr *pwr, struct pci_dev *pdev,
                             pci_power_t state, int id, int reg, int bit)
{
        const char *name;
        int ret;

        state = __find_weakest_power_state(pwr->lss[id], pdev, state);
        name = pci_power_name(state);

        ret = __update_power_state(pwr, reg, bit, (__force int)state);
        if (ret) {
                dev_warn(&pdev->dev, "Can't set power state %s: %d\n", name, ret);
                return ret;
        }

        dev_vdbg(&pdev->dev, "Set power state %s\n", name);
        return 0;
}

static int mid_pwr_set_power_state(struct mid_pwr *pwr, struct pci_dev *pdev,
                                   pci_power_t state)
{
        int id, reg, bit;
        int ret;

        id = intel_mid_pwr_get_lss_id(pdev);
        if (id < 0)
                return id;

        reg = (id * LSS_PWS_BITS) / 32;
        bit = (id * LSS_PWS_BITS) % 32;

        /* We support states between PCI_D0 and PCI_D3hot */
        if (state < PCI_D0)
                state = PCI_D0;
        if (state > PCI_D3hot)
                state = PCI_D3hot;

        mutex_lock(&pwr->lock);
        ret = __set_power_state(pwr, pdev, state, id, reg, bit);
        mutex_unlock(&pwr->lock);
        return ret;
}

int intel_mid_pci_set_power_state(struct pci_dev *pdev, pci_power_t state)
{
        struct mid_pwr *pwr = midpwr;
        int ret = 0;

        might_sleep();

        if (pwr && pwr->available)
                ret = mid_pwr_set_power_state(pwr, pdev, state);
        dev_vdbg(&pdev->dev, "set_power_state() returns %d\n", ret);

        return 0;
}

pci_power_t intel_mid_pci_get_power_state(struct pci_dev *pdev)
{
        struct mid_pwr *pwr = midpwr;
        int id, reg, bit;
        u32 power;

        if (!pwr || !pwr->available)
                return PCI_UNKNOWN;

        id = intel_mid_pwr_get_lss_id(pdev);
        if (id < 0)
                return PCI_UNKNOWN;

        reg = (id * LSS_PWS_BITS) / 32;
        bit = (id * LSS_PWS_BITS) % 32;
        power = mid_pwr_get_state(pwr, reg);
        return (__force pci_power_t)((power >> bit) & 3);
}

void intel_mid_pwr_power_off(void)
{
        struct mid_pwr *pwr = midpwr;
        u32 cmd = PM_CMD_SYS_STATE_S5 |
                  PM_CMD_CMD(CMD_SET_CFG) |
                  PM_CMD_CM_TRIGGER |
                  PM_CMD_CFG_TRIGGER_NC |
                  TRIGGER_NC_MSG_2;

        /* Send command to SCU */
        writel(cmd, pwr->regs + PM_CMD);
        mid_pwr_wait(pwr);
}

int intel_mid_pwr_get_lss_id(struct pci_dev *pdev)
{
        int vndr;
        u8 id;

        /*
         * Mapping to PWRMU index is kept in the Logical SubSystem ID byte of
         * Vendor capability.
         */
        vndr = pci_find_capability(pdev, PCI_CAP_ID_VNDR);
        if (!vndr)
                return -EINVAL;

        /* Read the Logical SubSystem ID byte */
        pci_read_config_byte(pdev, vndr + INTEL_MID_PWR_LSS_OFFSET, &id);
        if (!(id & INTEL_MID_PWR_LSS_TYPE))
                return -ENODEV;

        id &= ~INTEL_MID_PWR_LSS_TYPE;
        if (id >= LSS_MAX_DEVS)
                return -ERANGE;

        return id;
}

static irqreturn_t mid_pwr_irq_handler(int irq, void *dev_id)
{
        struct mid_pwr *pwr = dev_id;
        u32 ics;

        ics = readl(pwr->regs + PM_ICS);
        if (!(ics & PM_ICS_IP))
                return IRQ_NONE;

        writel(ics | PM_ICS_IP, pwr->regs + PM_ICS);

        dev_warn(pwr->dev, "Unexpected IRQ: %#x\n", PM_ICS_INT_STATUS(ics));
        return IRQ_HANDLED;
}

struct mid_pwr_device_info {
        int (*set_initial_state)(struct mid_pwr *pwr);
};

static int mid_pwr_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
        struct mid_pwr_device_info *info = (void *)id->driver_data;
        struct device *dev = &pdev->dev;
        struct mid_pwr *pwr;
        int ret;

        ret = pcim_enable_device(pdev);
        if (ret < 0) {
                dev_err(&pdev->dev, "error: could not enable device\n");
                return ret;
        }

        ret = pcim_iomap_regions(pdev, 1 << 0, pci_name(pdev));
        if (ret) {
                dev_err(&pdev->dev, "I/O memory remapping failed\n");
                return ret;
        }

        pwr = devm_kzalloc(dev, sizeof(*pwr), GFP_KERNEL);
        if (!pwr)
                return -ENOMEM;

        pwr->dev = dev;
        pwr->regs = pcim_iomap_table(pdev)[0];
        pwr->irq = pdev->irq;

        mutex_init(&pwr->lock);

        /* Disable interrupts */
        mid_pwr_interrupt_disable(pwr);

        if (info && info->set_initial_state) {
                ret = info->set_initial_state(pwr);
                if (ret)
                        dev_warn(dev, "Can't set initial state: %d\n", ret);
        }

        ret = devm_request_irq(dev, pdev->irq, mid_pwr_irq_handler,
                               IRQF_NO_SUSPEND, pci_name(pdev), pwr);
        if (ret)
                return ret;

        pwr->available = true;
        midpwr = pwr;

        pci_set_drvdata(pdev, pwr);
        return 0;
}

static int mid_set_initial_state(struct mid_pwr *pwr, const u32 *states)
{
        unsigned int i, j;
        int ret;

        /*
         * Enable wake events.
         *
         * PWRMU supports up to 32 sources for wake up the system. Ungate them
         * all here.
         */
        mid_pwr_set_wake(pwr, 0, 0xffffffff);
        mid_pwr_set_wake(pwr, 1, 0xffffffff);

        /*
         * Power off South Complex devices.
         *
         * There is a map (see a note below) of 64 devices with 2 bits per each
         * on 32-bit HW registers. The following calls set all devices to one
         * known initial state, i.e. PCI_D3hot. This is done in conjunction
         * with PMCSR setting in arch/x86/pci/intel_mid_pci.c.
         *
         * NOTE: The actual device mapping is provided by a platform at run
         * time using vendor capability of PCI configuration space.
         */
        mid_pwr_set_state(pwr, 0, states[0]);
        mid_pwr_set_state(pwr, 1, states[1]);
        mid_pwr_set_state(pwr, 2, states[2]);
        mid_pwr_set_state(pwr, 3, states[3]);

        /* Send command to SCU */
        ret = mid_pwr_wait_for_cmd(pwr, CMD_SET_CFG);
        if (ret)
                return ret;

        for (i = 0; i < LSS_MAX_DEVS; i++) {
                for (j = 0; j < LSS_MAX_SHARED_DEVS; j++)
                        pwr->lss[i][j].state = PCI_D3hot;
        }

        return 0;
}

static int pnw_set_initial_state(struct mid_pwr *pwr)
{
        /* On Penwell SRAM must stay powered on */
        static const u32 states[] = {
                0xf00fffff,             /* PM_SSC(0) */
                0xffffffff,             /* PM_SSC(1) */
                0xffffffff,             /* PM_SSC(2) */
                0xffffffff,             /* PM_SSC(3) */
        };
        return mid_set_initial_state(pwr, states);
}

static int tng_set_initial_state(struct mid_pwr *pwr)
{
        static const u32 states[] = {
                0xffffffff,             /* PM_SSC(0) */
                0xffffffff,             /* PM_SSC(1) */
                0xffffffff,             /* PM_SSC(2) */
                0xffffffff,             /* PM_SSC(3) */
        };
        return mid_set_initial_state(pwr, states);
}

static const struct mid_pwr_device_info pnw_info = {
        .set_initial_state = pnw_set_initial_state,
};

static const struct mid_pwr_device_info tng_info = {
        .set_initial_state = tng_set_initial_state,
};

/* This table should be in sync with the one in drivers/pci/pci-mid.c */
static const struct pci_device_id mid_pwr_pci_ids[] = {
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_PENWELL), (kernel_ulong_t)&pnw_info },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_TANGIER), (kernel_ulong_t)&tng_info },
        {}
};

static struct pci_driver mid_pwr_pci_driver = {
        .name           = "intel_mid_pwr",
        .probe          = mid_pwr_probe,
        .id_table       = mid_pwr_pci_ids,
};

builtin_pci_driver(mid_pwr_pci_driver);