/*
 * intel_scu_ipc.c: Driver for the Intel SCU IPC mechanism
 *
 * (C) Copyright 2008-2010 Intel Corporation
 * Author: Sreedhara DS (sreedhara.ds@intel.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; version 2
 * of the License.
 *
 * SCU running in ARC processor communicates with other entity running in IA
 * core through IPC mechanism which in turn messaging between IA core ad SCU.
 * SCU has two IPC mechanism IPC-1 and IPC-2. IPC-1 is used between IA32 and
 * SCU where IPC-2 is used between P-Unit and SCU. This driver delas with
 * IPC-1 Driver provides an API for power control unit registers (e.g. MSIC)
 * along with other APIs.
 */
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/pm.h>
#include <linux/pci.h>
#include <linux/interrupt.h>
#include <linux/sfi.h>
#include <linux/module.h>
#include <asm/mrst.h>
#include <asm/intel_scu_ipc.h>

/* IPC defines the following message types */
#define IPCMSG_WATCHDOG_TIMER 0xF8 /* Set Kernel Watchdog Threshold */
#define IPCMSG_BATTERY        0xEF /* Coulomb Counter Accumulator */
#define IPCMSG_FW_UPDATE      0xFE /* Firmware update */
#define IPCMSG_PCNTRL         0xFF /* Power controller unit read/write */
#define IPCMSG_FW_REVISION    0xF4 /* Get firmware revision */

/* Command id associated with message IPCMSG_PCNTRL */
#define IPC_CMD_PCNTRL_W      0 /* Register write */
#define IPC_CMD_PCNTRL_R      1 /* Register read */
#define IPC_CMD_PCNTRL_M      2 /* Register read-modify-write */

/*
 * IPC register summary
 *
 * IPC register blocks are memory mapped at fixed address of 0xFF11C000
 * To read or write information to the SCU, driver writes to IPC-1 memory
 * mapped registers (base address 0xFF11C000). The following is the IPC
 * mechanism
 *
 * 1. IA core cDMI interface claims this transaction and converts it to a
 *    Transaction Layer Packet (TLP) message which is sent across the cDMI.
 *
 * 2. South Complex cDMI block receives this message and writes it to
 *    the IPC-1 register block, causing an interrupt to the SCU
 *
 * 3. SCU firmware decodes this interrupt and IPC message and the appropriate
 *    message handler is called within firmware.
 */

#define IPC_BASE_ADDR     0xFF11C000    /* IPC1 base register address */
#define IPC_MAX_ADDR      0x100         /* Maximum IPC regisers */
#define IPC_WWBUF_SIZE    20            /* IPC Write buffer Size */
#define IPC_RWBUF_SIZE    20            /* IPC Read buffer Size */
#define IPC_I2C_BASE      0xFF12B000    /* I2C control register base address */
#define IPC_I2C_MAX_ADDR  0x10          /* Maximum I2C regisers */

static int ipc_probe(struct pci_dev *dev, const struct pci_device_id *id);
static void ipc_remove(struct pci_dev *pdev);

struct intel_scu_ipc_dev {
        struct pci_dev *pdev;
        void __iomem *ipc_base;
        void __iomem *i2c_base;
};

static struct intel_scu_ipc_dev  ipcdev; /* Only one for now */

static int platform;            /* Platform type */

/*
 * IPC Read Buffer (Read Only):
 * 16 byte buffer for receiving data from SCU, if IPC command
 * processing results in response data
 */
#define IPC_READ_BUFFER         0x90

#define IPC_I2C_CNTRL_ADDR      0
#define I2C_DATA_ADDR           0x04

static DEFINE_MUTEX(ipclock); /* lock used to prevent multiple call to SCU */

/*
 * Command Register (Write Only):
 * A write to this register results in an interrupt to the SCU core processor
 * Format:
 * |rfu2(8) | size(8) | command id(4) | rfu1(3) | ioc(1) | command(8)|
 */
static inline void ipc_command(u32 cmd) /* Send ipc command */
{
        writel(cmd, ipcdev.ipc_base);
}

/*
 * IPC Write Buffer (Write Only):
 * 16-byte buffer for sending data associated with IPC command to
 * SCU. Size of the data is specified in the IPC_COMMAND_REG register
 */
static inline void ipc_data_writel(u32 data, u32 offset) /* Write ipc data */
{
        writel(data, ipcdev.ipc_base + 0x80 + offset);
}

/*
 * Status Register (Read Only):
 * Driver will read this register to get the ready/busy status of the IPC
 * block and error status of the IPC command that was just processed by SCU
 * Format:
 * |rfu3(8)|error code(8)|initiator id(8)|cmd id(4)|rfu1(2)|error(1)|busy(1)|
 */

static inline u8 ipc_read_status(void)
{
        return __raw_readl(ipcdev.ipc_base + 0x04);
}

static inline u8 ipc_data_readb(u32 offset) /* Read ipc byte data */
{
        return readb(ipcdev.ipc_base + IPC_READ_BUFFER + offset);
}

static inline u32 ipc_data_readl(u32 offset) /* Read ipc u32 data */
{
        return readl(ipcdev.ipc_base + IPC_READ_BUFFER + offset);
}

static inline int busy_loop(void) /* Wait till scu status is busy */
{
        u32 status = 0;
        u32 loop_count = 0;

        status = ipc_read_status();
        while (status & 1) {
                udelay(1); /* scu processing time is in few u secods */
                status = ipc_read_status();
                loop_count++;
                /* break if scu doesn't reset busy bit after huge retry */
                if (loop_count > 100000) {
                        dev_err(&ipcdev.pdev->dev, "IPC timed out");
                        return -ETIMEDOUT;
                }
        }
        if ((status >> 1) & 1)
                return -EIO;

        return 0;
}

/* Read/Write power control(PMIC in Langwell, MSIC in PenWell) registers */
static int pwr_reg_rdwr(u16 *addr, u8 *data, u32 count, u32 op, u32 id)
{
        int nc;
        u32 offset = 0;
        int err;
        u8 cbuf[IPC_WWBUF_SIZE] = { };
        u32 *wbuf = (u32 *)&cbuf;

        mutex_lock(&ipclock);

        memset(cbuf, 0, sizeof(cbuf));

        if (ipcdev.pdev == NULL) {
                mutex_unlock(&ipclock);
                return -ENODEV;
        }

        for (nc = 0; nc < count; nc++, offset += 2) {
                cbuf[offset] = addr[nc];
                cbuf[offset + 1] = addr[nc] >> 8;
        }

        if (id == IPC_CMD_PCNTRL_R) {
                for (nc = 0, offset = 0; nc < count; nc++, offset += 4)
                        ipc_data_writel(wbuf[nc], offset);
                ipc_command((count*2) << 16 |  id << 12 | 0 << 8 | op);
        } else if (id == IPC_CMD_PCNTRL_W) {
                for (nc = 0; nc < count; nc++, offset += 1)
                        cbuf[offset] = data[nc];
                for (nc = 0, offset = 0; nc < count; nc++, offset += 4)
                        ipc_data_writel(wbuf[nc], offset);
                ipc_command((count*3) << 16 |  id << 12 | 0 << 8 | op);
        } else if (id == IPC_CMD_PCNTRL_M) {
                cbuf[offset] = data[0];
                cbuf[offset + 1] = data[1];
                ipc_data_writel(wbuf[0], 0); /* Write wbuff */
                ipc_command(4 << 16 |  id << 12 | 0 << 8 | op);
        }

        err = busy_loop();
        if (id == IPC_CMD_PCNTRL_R) { /* Read rbuf */
                /* Workaround: values are read as 0 without memcpy_fromio */
                memcpy_fromio(cbuf, ipcdev.ipc_base + 0x90, 16);
                for (nc = 0; nc < count; nc++)
                        data[nc] = ipc_data_readb(nc);
        }
        mutex_unlock(&ipclock);
        return err;
}

/**
 *      intel_scu_ipc_ioread8           -       read a word via the SCU
 *      @addr: register on SCU
 *      @data: return pointer for read byte
 *
 *      Read a single register. Returns 0 on success or an error code. All
 *      locking between SCU accesses is handled for the caller.
 *
 *      This function may sleep.
 */
int intel_scu_ipc_ioread8(u16 addr, u8 *data)
{
        return pwr_reg_rdwr(&addr, data, 1, IPCMSG_PCNTRL, IPC_CMD_PCNTRL_R);
}
EXPORT_SYMBOL(intel_scu_ipc_ioread8);

/**
 *      intel_scu_ipc_ioread16          -       read a word via the SCU
 *      @addr: register on SCU
 *      @data: return pointer for read word
 *
 *      Read a register pair. Returns 0 on success or an error code. All
 *      locking between SCU accesses is handled for the caller.
 *
 *      This function may sleep.
 */
int intel_scu_ipc_ioread16(u16 addr, u16 *data)
{
        u16 x[2] = {addr, addr + 1 };
        return pwr_reg_rdwr(x, (u8 *)data, 2, IPCMSG_PCNTRL, IPC_CMD_PCNTRL_R);
}
EXPORT_SYMBOL(intel_scu_ipc_ioread16);

/**
 *      intel_scu_ipc_ioread32          -       read a dword via the SCU
 *      @addr: register on SCU
 *      @data: return pointer for read dword
 *
 *      Read four registers. Returns 0 on success or an error code. All
 *      locking between SCU accesses is handled for the caller.
 *
 *      This function may sleep.
 */
int intel_scu_ipc_ioread32(u16 addr, u32 *data)
{
        u16 x[4] = {addr, addr + 1, addr + 2, addr + 3};
        return pwr_reg_rdwr(x, (u8 *)data, 4, IPCMSG_PCNTRL, IPC_CMD_PCNTRL_R);
}
EXPORT_SYMBOL(intel_scu_ipc_ioread32);

/**
 *      intel_scu_ipc_iowrite8          -       write a byte via the SCU
 *      @addr: register on SCU
 *      @data: byte to write
 *
 *      Write a single register. Returns 0 on success or an error code. All
 *      locking between SCU accesses is handled for the caller.
 *
 *      This function may sleep.
 */
int intel_scu_ipc_iowrite8(u16 addr, u8 data)
{
        return pwr_reg_rdwr(&addr, &data, 1, IPCMSG_PCNTRL, IPC_CMD_PCNTRL_W);
}
EXPORT_SYMBOL(intel_scu_ipc_iowrite8);

/**
 *      intel_scu_ipc_iowrite16         -       write a word via the SCU
 *      @addr: register on SCU
 *      @data: word to write
 *
 *      Write two registers. Returns 0 on success or an error code. All
 *      locking between SCU accesses is handled for the caller.
 *
 *      This function may sleep.
 */
int intel_scu_ipc_iowrite16(u16 addr, u16 data)
{
        u16 x[2] = {addr, addr + 1 };
        return pwr_reg_rdwr(x, (u8 *)&data, 2, IPCMSG_PCNTRL, IPC_CMD_PCNTRL_W);
}
EXPORT_SYMBOL(intel_scu_ipc_iowrite16);

/**
 *      intel_scu_ipc_iowrite32         -       write a dword via the SCU
 *      @addr: register on SCU
 *      @data: dword to write
 *
 *      Write four registers. Returns 0 on success or an error code. All
 *      locking between SCU accesses is handled for the caller.
 *
 *      This function may sleep.
 */
int intel_scu_ipc_iowrite32(u16 addr, u32 data)
{
        u16 x[4] = {addr, addr + 1, addr + 2, addr + 3};
        return pwr_reg_rdwr(x, (u8 *)&data, 4, IPCMSG_PCNTRL, IPC_CMD_PCNTRL_W);
}
EXPORT_SYMBOL(intel_scu_ipc_iowrite32);

/**
 *      intel_scu_ipc_readvv            -       read a set of registers
 *      @addr: register list
 *      @data: bytes to return
 *      @len: length of array
 *
 *      Read registers. Returns 0 on success or an error code. All
 *      locking between SCU accesses is handled for the caller.
 *
 *      The largest array length permitted by the hardware is 5 items.
 *
 *      This function may sleep.
 */
int intel_scu_ipc_readv(u16 *addr, u8 *data, int len)
{
        return pwr_reg_rdwr(addr, data, len, IPCMSG_PCNTRL, IPC_CMD_PCNTRL_R);
}
EXPORT_SYMBOL(intel_scu_ipc_readv);

/**
 *      intel_scu_ipc_writev            -       write a set of registers
 *      @addr: register list
 *      @data: bytes to write
 *      @len: length of array
 *
 *      Write registers. Returns 0 on success or an error code. All
 *      locking between SCU accesses is handled for the caller.
 *
 *      The largest array length permitted by the hardware is 5 items.
 *
 *      This function may sleep.
 *
 */
int intel_scu_ipc_writev(u16 *addr, u8 *data, int len)
{
        return pwr_reg_rdwr(addr, data, len, IPCMSG_PCNTRL, IPC_CMD_PCNTRL_W);
}
EXPORT_SYMBOL(intel_scu_ipc_writev);


/**
 *      intel_scu_ipc_update_register   -       r/m/w a register
 *      @addr: register address
 *      @bits: bits to update
 *      @mask: mask of bits to update
 *
 *      Read-modify-write power control unit register. The first data argument
 *      must be register value and second is mask value
 *      mask is a bitmap that indicates which bits to update.
 *      0 = masked. Don't modify this bit, 1 = modify this bit.
 *      returns 0 on success or an error code.
 *
 *      This function may sleep. Locking between SCU accesses is handled
 *      for the caller.
 */
int intel_scu_ipc_update_register(u16 addr, u8 bits, u8 mask)
{
        u8 data[2] = { bits, mask };
        return pwr_reg_rdwr(&addr, data, 1, IPCMSG_PCNTRL, IPC_CMD_PCNTRL_M);
}
EXPORT_SYMBOL(intel_scu_ipc_update_register);

/**
 *      intel_scu_ipc_simple_command    -       send a simple command
 *      @cmd: command
 *      @sub: sub type
 *
 *      Issue a simple command to the SCU. Do not use this interface if
 *      you must then access data as any data values may be overwritten
 *      by another SCU access by the time this function returns.
 *
 *      This function may sleep. Locking for SCU accesses is handled for
 *      the caller.
 */
int intel_scu_ipc_simple_command(int cmd, int sub)
{
        int err;

        mutex_lock(&ipclock);
        if (ipcdev.pdev == NULL) {
                mutex_unlock(&ipclock);
                return -ENODEV;
        }
        ipc_command(sub << 12 | cmd);
        err = busy_loop();
        mutex_unlock(&ipclock);
        return err;
}
EXPORT_SYMBOL(intel_scu_ipc_simple_command);

/**
 *      intel_scu_ipc_command   -       command with data
 *      @cmd: command
 *      @sub: sub type
 *      @in: input data
 *      @inlen: input length in dwords
 *      @out: output data
 *      @outlein: output length in dwords
 *
 *      Issue a command to the SCU which involves data transfers. Do the
 *      data copies under the lock but leave it for the caller to interpret
 */

int intel_scu_ipc_command(int cmd, int sub, u32 *in, int inlen,
                                                        u32 *out, int outlen)
{
        int i, err;

        mutex_lock(&ipclock);
        if (ipcdev.pdev == NULL) {
                mutex_unlock(&ipclock);
                return -ENODEV;
        }

        for (i = 0; i < inlen; i++)
                ipc_data_writel(*in++, 4 * i);

        ipc_command((inlen << 16) | (sub << 12) | cmd);
        err = busy_loop();

        for (i = 0; i < outlen; i++)
                *out++ = ipc_data_readl(4 * i);

        mutex_unlock(&ipclock);
        return err;
}
EXPORT_SYMBOL(intel_scu_ipc_command);

/*I2C commands */
#define IPC_I2C_WRITE 1 /* I2C Write command */
#define IPC_I2C_READ  2 /* I2C Read command */

/**
 *      intel_scu_ipc_i2c_cntrl         -       I2C read/write operations
 *      @addr: I2C address + command bits
 *      @data: data to read/write
 *
 *      Perform an an I2C read/write operation via the SCU. All locking is
 *      handled for the caller. This function may sleep.
 *
 *      Returns an error code or 0 on success.
 *
 *      This has to be in the IPC driver for the locking.
 */
int intel_scu_ipc_i2c_cntrl(u32 addr, u32 *data)
{
        u32 cmd = 0;

        mutex_lock(&ipclock);
        if (ipcdev.pdev == NULL) {
                mutex_unlock(&ipclock);
                return -ENODEV;
        }
        cmd = (addr >> 24) & 0xFF;
        if (cmd == IPC_I2C_READ) {
                writel(addr, ipcdev.i2c_base + IPC_I2C_CNTRL_ADDR);
                /* Write not getting updated without delay */
                mdelay(1);
                *data = readl(ipcdev.i2c_base + I2C_DATA_ADDR);
        } else if (cmd == IPC_I2C_WRITE) {
                writel(*data, ipcdev.i2c_base + I2C_DATA_ADDR);
                mdelay(1);
                writel(addr, ipcdev.i2c_base + IPC_I2C_CNTRL_ADDR);
        } else {
                dev_err(&ipcdev.pdev->dev,
                        "intel_scu_ipc: I2C INVALID_CMD = 0x%x\n", cmd);

                mutex_unlock(&ipclock);
                return -EIO;
        }
        mutex_unlock(&ipclock);
        return 0;
}
EXPORT_SYMBOL(intel_scu_ipc_i2c_cntrl);

/*
 * Interrupt handler gets called when ioc bit of IPC_COMMAND_REG set to 1
 * When ioc bit is set to 1, caller api must wait for interrupt handler called
 * which in turn unlocks the caller api. Currently this is not used
 *
 * This is edge triggered so we need take no action to clear anything
 */
static irqreturn_t ioc(int irq, void *dev_id)
{
        return IRQ_HANDLED;
}

/**
 *      ipc_probe       -       probe an Intel SCU IPC
 *      @dev: the PCI device matching
 *      @id: entry in the match table
 *
 *      Enable and install an intel SCU IPC. This appears in the PCI space
 *      but uses some hard coded addresses as well.
 */
static int ipc_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
        int err;
        resource_size_t pci_resource;

        if (ipcdev.pdev)                /* We support only one SCU */
                return -EBUSY;

        ipcdev.pdev = pci_dev_get(dev);

        err = pci_enable_device(dev);
        if (err)
                return err;

        err = pci_request_regions(dev, "intel_scu_ipc");
        if (err)
                return err;

        pci_resource = pci_resource_start(dev, 0);
        if (!pci_resource)
                return -ENOMEM;

        if (request_irq(dev->irq, ioc, 0, "intel_scu_ipc", &ipcdev))
                return -EBUSY;

        ipcdev.ipc_base = ioremap_nocache(IPC_BASE_ADDR, IPC_MAX_ADDR);
        if (!ipcdev.ipc_base)
                return -ENOMEM;

        ipcdev.i2c_base = ioremap_nocache(IPC_I2C_BASE, IPC_I2C_MAX_ADDR);
        if (!ipcdev.i2c_base) {
                iounmap(ipcdev.ipc_base);
                return -ENOMEM;
        }

        intel_scu_devices_create();

        return 0;
}

/**
 *      ipc_remove      -       remove a bound IPC device
 *      @pdev: PCI device
 *
 *      In practice the SCU is not removable but this function is also
 *      called for each device on a module unload or cleanup which is the
 *      path that will get used.
 *
 *      Free up the mappings and release the PCI resources
 */
static void ipc_remove(struct pci_dev *pdev)
{
        free_irq(pdev->irq, &ipcdev);
        pci_release_regions(pdev);
        pci_dev_put(ipcdev.pdev);
        iounmap(ipcdev.ipc_base);
        iounmap(ipcdev.i2c_base);
        ipcdev.pdev = NULL;
        intel_scu_devices_destroy();
}

static DEFINE_PCI_DEVICE_TABLE(pci_ids) = {
        {PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x082a)},
        { 0,}
};
MODULE_DEVICE_TABLE(pci, pci_ids);

static struct pci_driver ipc_driver = {
        .name = "intel_scu_ipc",
        .id_table = pci_ids,
        .probe = ipc_probe,
        .remove = ipc_remove,
};


static int __init intel_scu_ipc_init(void)
{
        platform = mrst_identify_cpu();
        if (platform == 0)
                return -ENODEV;
        return  pci_register_driver(&ipc_driver);
}

static void __exit intel_scu_ipc_exit(void)
{
        pci_unregister_driver(&ipc_driver);
}

MODULE_AUTHOR("Sreedhara DS <sreedhara.ds@intel.com>");
MODULE_DESCRIPTION("Intel SCU IPC driver");
MODULE_LICENSE("GPL");

module_init(intel_scu_ipc_init);
module_exit(intel_scu_ipc_exit);