treewide: remove redundant IS_ERR() before error code check

[linux/fpc-iii.git] / drivers / soundwire / bus.c

// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
// Copyright(c) 2015-17 Intel Corporation.

#include <linux/acpi.h>
#include <linux/mod_devicetable.h>
#include <linux/pm_runtime.h>
#include <linux/soundwire/sdw_registers.h>
#include <linux/soundwire/sdw.h>
#include "bus.h"

/**
 * sdw_add_bus_master() - add a bus Master instance
 * @bus: bus instance
 *
 * Initializes the bus instance, read properties and create child
 * devices.
 */
int sdw_add_bus_master(struct sdw_bus *bus)
{
        struct sdw_master_prop *prop = NULL;
        int ret;

        if (!bus->dev) {
                pr_err("SoundWire bus has no device\n");
                return -ENODEV;
        }

        if (!bus->ops) {
                dev_err(bus->dev, "SoundWire Bus ops are not set\n");
                return -EINVAL;
        }

        mutex_init(&bus->msg_lock);
        mutex_init(&bus->bus_lock);
        INIT_LIST_HEAD(&bus->slaves);
        INIT_LIST_HEAD(&bus->m_rt_list);

        /*
         * Initialize multi_link flag
         * TODO: populate this flag by reading property from FW node
         */
        bus->multi_link = false;
        if (bus->ops->read_prop) {
                ret = bus->ops->read_prop(bus);
                if (ret < 0) {
                        dev_err(bus->dev,
                                "Bus read properties failed:%d\n", ret);
                        return ret;
                }
        }

        sdw_bus_debugfs_init(bus);

        /*
         * Device numbers in SoundWire are 0 through 15. Enumeration device
         * number (0), Broadcast device number (15), Group numbers (12 and
         * 13) and Master device number (14) are not used for assignment so
         * mask these and other higher bits.
         */

        /* Set higher order bits */
        *bus->assigned = ~GENMASK(SDW_BROADCAST_DEV_NUM, SDW_ENUM_DEV_NUM);

        /* Set enumuration device number and broadcast device number */
        set_bit(SDW_ENUM_DEV_NUM, bus->assigned);
        set_bit(SDW_BROADCAST_DEV_NUM, bus->assigned);

        /* Set group device numbers and master device number */
        set_bit(SDW_GROUP12_DEV_NUM, bus->assigned);
        set_bit(SDW_GROUP13_DEV_NUM, bus->assigned);
        set_bit(SDW_MASTER_DEV_NUM, bus->assigned);

        /*
         * SDW is an enumerable bus, but devices can be powered off. So,
         * they won't be able to report as present.
         *
         * Create Slave devices based on Slaves described in
         * the respective firmware (ACPI/DT)
         */
        if (IS_ENABLED(CONFIG_ACPI) && ACPI_HANDLE(bus->dev))
                ret = sdw_acpi_find_slaves(bus);
        else if (IS_ENABLED(CONFIG_OF) && bus->dev->of_node)
                ret = sdw_of_find_slaves(bus);
        else
                ret = -ENOTSUPP; /* No ACPI/DT so error out */

        if (ret) {
                dev_err(bus->dev, "Finding slaves failed:%d\n", ret);
                return ret;
        }

        /*
         * Initialize clock values based on Master properties. The max
         * frequency is read from max_clk_freq property. Current assumption
         * is that the bus will start at highest clock frequency when
         * powered on.
         *
         * Default active bank will be 0 as out of reset the Slaves have
         * to start with bank 0 (Table 40 of Spec)
         */
        prop = &bus->prop;
        bus->params.max_dr_freq = prop->max_clk_freq * SDW_DOUBLE_RATE_FACTOR;
        bus->params.curr_dr_freq = bus->params.max_dr_freq;
        bus->params.curr_bank = SDW_BANK0;
        bus->params.next_bank = SDW_BANK1;

        return 0;
}
EXPORT_SYMBOL(sdw_add_bus_master);

static int sdw_delete_slave(struct device *dev, void *data)
{
        struct sdw_slave *slave = dev_to_sdw_dev(dev);
        struct sdw_bus *bus = slave->bus;

        sdw_slave_debugfs_exit(slave);

        mutex_lock(&bus->bus_lock);

        if (slave->dev_num) /* clear dev_num if assigned */
                clear_bit(slave->dev_num, bus->assigned);

        list_del_init(&slave->node);
        mutex_unlock(&bus->bus_lock);

        device_unregister(dev);
        return 0;
}

/**
 * sdw_delete_bus_master() - delete the bus master instance
 * @bus: bus to be deleted
 *
 * Remove the instance, delete the child devices.
 */
void sdw_delete_bus_master(struct sdw_bus *bus)
{
        device_for_each_child(bus->dev, NULL, sdw_delete_slave);

        sdw_bus_debugfs_exit(bus);
}
EXPORT_SYMBOL(sdw_delete_bus_master);

/*
 * SDW IO Calls
 */

static inline int find_response_code(enum sdw_command_response resp)
{
        switch (resp) {
        case SDW_CMD_OK:
                return 0;

        case SDW_CMD_IGNORED:
                return -ENODATA;

        case SDW_CMD_TIMEOUT:
                return -ETIMEDOUT;

        default:
                return -EIO;
        }
}

static inline int do_transfer(struct sdw_bus *bus, struct sdw_msg *msg)
{
        int retry = bus->prop.err_threshold;
        enum sdw_command_response resp;
        int ret = 0, i;

        for (i = 0; i <= retry; i++) {
                resp = bus->ops->xfer_msg(bus, msg);
                ret = find_response_code(resp);

                /* if cmd is ok or ignored return */
                if (ret == 0 || ret == -ENODATA)
                        return ret;
        }

        return ret;
}

static inline int do_transfer_defer(struct sdw_bus *bus,
                                    struct sdw_msg *msg,
                                    struct sdw_defer *defer)
{
        int retry = bus->prop.err_threshold;
        enum sdw_command_response resp;
        int ret = 0, i;

        defer->msg = msg;
        defer->length = msg->len;
        init_completion(&defer->complete);

        for (i = 0; i <= retry; i++) {
                resp = bus->ops->xfer_msg_defer(bus, msg, defer);
                ret = find_response_code(resp);
                /* if cmd is ok or ignored return */
                if (ret == 0 || ret == -ENODATA)
                        return ret;
        }

        return ret;
}

static int sdw_reset_page(struct sdw_bus *bus, u16 dev_num)
{
        int retry = bus->prop.err_threshold;
        enum sdw_command_response resp;
        int ret = 0, i;

        for (i = 0; i <= retry; i++) {
                resp = bus->ops->reset_page_addr(bus, dev_num);
                ret = find_response_code(resp);
                /* if cmd is ok or ignored return */
                if (ret == 0 || ret == -ENODATA)
                        return ret;
        }

        return ret;
}

/**
 * sdw_transfer() - Synchronous transfer message to a SDW Slave device
 * @bus: SDW bus
 * @msg: SDW message to be xfered
 */
int sdw_transfer(struct sdw_bus *bus, struct sdw_msg *msg)
{
        int ret;

        mutex_lock(&bus->msg_lock);

        ret = do_transfer(bus, msg);
        if (ret != 0 && ret != -ENODATA)
                dev_err(bus->dev, "trf on Slave %d failed:%d\n",
                        msg->dev_num, ret);

        if (msg->page)
                sdw_reset_page(bus, msg->dev_num);

        mutex_unlock(&bus->msg_lock);

        return ret;
}

/**
 * sdw_transfer_defer() - Asynchronously transfer message to a SDW Slave device
 * @bus: SDW bus
 * @msg: SDW message to be xfered
 * @defer: Defer block for signal completion
 *
 * Caller needs to hold the msg_lock lock while calling this
 */
int sdw_transfer_defer(struct sdw_bus *bus, struct sdw_msg *msg,
                       struct sdw_defer *defer)
{
        int ret;

        if (!bus->ops->xfer_msg_defer)
                return -ENOTSUPP;

        ret = do_transfer_defer(bus, msg, defer);
        if (ret != 0 && ret != -ENODATA)
                dev_err(bus->dev, "Defer trf on Slave %d failed:%d\n",
                        msg->dev_num, ret);

        if (msg->page)
                sdw_reset_page(bus, msg->dev_num);

        return ret;
}

int sdw_fill_msg(struct sdw_msg *msg, struct sdw_slave *slave,
                 u32 addr, size_t count, u16 dev_num, u8 flags, u8 *buf)
{
        memset(msg, 0, sizeof(*msg));
        msg->addr = addr; /* addr is 16 bit and truncated here */
        msg->len = count;
        msg->dev_num = dev_num;
        msg->flags = flags;
        msg->buf = buf;

        if (addr < SDW_REG_NO_PAGE) { /* no paging area */
                return 0;
        } else if (addr >= SDW_REG_MAX) { /* illegal addr */
                pr_err("SDW: Invalid address %x passed\n", addr);
                return -EINVAL;
        }

        if (addr < SDW_REG_OPTIONAL_PAGE) { /* 32k but no page */
                if (slave && !slave->prop.paging_support)
                        return 0;
                /* no need for else as that will fall-through to paging */
        }

        /* paging mandatory */
        if (dev_num == SDW_ENUM_DEV_NUM || dev_num == SDW_BROADCAST_DEV_NUM) {
                pr_err("SDW: Invalid device for paging :%d\n", dev_num);
                return -EINVAL;
        }

        if (!slave) {
                pr_err("SDW: No slave for paging addr\n");
                return -EINVAL;
        } else if (!slave->prop.paging_support) {
                dev_err(&slave->dev,
                        "address %x needs paging but no support\n", addr);
                return -EINVAL;
        }

        msg->addr_page1 = (addr >> SDW_REG_SHIFT(SDW_SCP_ADDRPAGE1_MASK));
        msg->addr_page2 = (addr >> SDW_REG_SHIFT(SDW_SCP_ADDRPAGE2_MASK));
        msg->addr |= BIT(15);
        msg->page = true;

        return 0;
}

/**
 * sdw_nread() - Read "n" contiguous SDW Slave registers
 * @slave: SDW Slave
 * @addr: Register address
 * @count: length
 * @val: Buffer for values to be read
 */
int sdw_nread(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
{
        struct sdw_msg msg;
        int ret;

        ret = sdw_fill_msg(&msg, slave, addr, count,
                           slave->dev_num, SDW_MSG_FLAG_READ, val);
        if (ret < 0)
                return ret;

        ret = pm_runtime_get_sync(slave->bus->dev);
        if (ret < 0)
                return ret;

        ret = sdw_transfer(slave->bus, &msg);
        pm_runtime_put(slave->bus->dev);

        return ret;
}
EXPORT_SYMBOL(sdw_nread);

/**
 * sdw_nwrite() - Write "n" contiguous SDW Slave registers
 * @slave: SDW Slave
 * @addr: Register address
 * @count: length
 * @val: Buffer for values to be read
 */
int sdw_nwrite(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
{
        struct sdw_msg msg;
        int ret;

        ret = sdw_fill_msg(&msg, slave, addr, count,
                           slave->dev_num, SDW_MSG_FLAG_WRITE, val);
        if (ret < 0)
                return ret;

        ret = pm_runtime_get_sync(slave->bus->dev);
        if (ret < 0)
                return ret;

        ret = sdw_transfer(slave->bus, &msg);
        pm_runtime_put(slave->bus->dev);

        return ret;
}
EXPORT_SYMBOL(sdw_nwrite);

/**
 * sdw_read() - Read a SDW Slave register
 * @slave: SDW Slave
 * @addr: Register address
 */
int sdw_read(struct sdw_slave *slave, u32 addr)
{
        u8 buf;
        int ret;

        ret = sdw_nread(slave, addr, 1, &buf);
        if (ret < 0)
                return ret;
        else
                return buf;
}
EXPORT_SYMBOL(sdw_read);

/**
 * sdw_write() - Write a SDW Slave register
 * @slave: SDW Slave
 * @addr: Register address
 * @value: Register value
 */
int sdw_write(struct sdw_slave *slave, u32 addr, u8 value)
{
        return sdw_nwrite(slave, addr, 1, &value);
}
EXPORT_SYMBOL(sdw_write);

/*
 * SDW alert handling
 */

/* called with bus_lock held */
static struct sdw_slave *sdw_get_slave(struct sdw_bus *bus, int i)
{
        struct sdw_slave *slave = NULL;

        list_for_each_entry(slave, &bus->slaves, node) {
                if (slave->dev_num == i)
                        return slave;
        }

        return NULL;
}

static int sdw_compare_devid(struct sdw_slave *slave, struct sdw_slave_id id)
{
        if (slave->id.mfg_id != id.mfg_id ||
            slave->id.part_id != id.part_id ||
            slave->id.class_id != id.class_id ||
            (slave->id.unique_id != SDW_IGNORED_UNIQUE_ID &&
             slave->id.unique_id != id.unique_id))
                return -ENODEV;

        return 0;
}

/* called with bus_lock held */
static int sdw_get_device_num(struct sdw_slave *slave)
{
        int bit;

        bit = find_first_zero_bit(slave->bus->assigned, SDW_MAX_DEVICES);
        if (bit == SDW_MAX_DEVICES) {
                bit = -ENODEV;
                goto err;
        }

        /*
         * Do not update dev_num in Slave data structure here,
         * Update once program dev_num is successful
         */
        set_bit(bit, slave->bus->assigned);

err:
        return bit;
}

static int sdw_assign_device_num(struct sdw_slave *slave)
{
        int ret, dev_num;
        bool new_device = false;

        /* check first if device number is assigned, if so reuse that */
        if (!slave->dev_num) {
                if (!slave->dev_num_sticky) {
                        mutex_lock(&slave->bus->bus_lock);
                        dev_num = sdw_get_device_num(slave);
                        mutex_unlock(&slave->bus->bus_lock);
                        if (dev_num < 0) {
                                dev_err(slave->bus->dev, "Get dev_num failed: %d\n",
                                        dev_num);
                                return dev_num;
                        }
                        slave->dev_num = dev_num;
                        slave->dev_num_sticky = dev_num;
                        new_device = true;
                } else {
                        slave->dev_num = slave->dev_num_sticky;
                }
        }

        if (!new_device)
                dev_info(slave->bus->dev,
                         "Slave already registered, reusing dev_num:%d\n",
                         slave->dev_num);

        /* Clear the slave->dev_num to transfer message on device 0 */
        dev_num = slave->dev_num;
        slave->dev_num = 0;

        ret = sdw_write(slave, SDW_SCP_DEVNUMBER, dev_num);
        if (ret < 0) {
                dev_err(&slave->dev, "Program device_num %d failed: %d\n",
                        dev_num, ret);
                return ret;
        }

        /* After xfer of msg, restore dev_num */
        slave->dev_num = slave->dev_num_sticky;

        return 0;
}

void sdw_extract_slave_id(struct sdw_bus *bus,
                          u64 addr, struct sdw_slave_id *id)
{
        dev_dbg(bus->dev, "SDW Slave Addr: %llx\n", addr);

        /*
         * Spec definition
         *   Register           Bit     Contents
         *   DevId_0 [7:4]      47:44   sdw_version
         *   DevId_0 [3:0]      43:40   unique_id
         *   DevId_1            39:32   mfg_id [15:8]
         *   DevId_2            31:24   mfg_id [7:0]
         *   DevId_3            23:16   part_id [15:8]
         *   DevId_4            15:08   part_id [7:0]
         *   DevId_5            07:00   class_id
         */
        id->sdw_version = (addr >> 44) & GENMASK(3, 0);
        id->unique_id = (addr >> 40) & GENMASK(3, 0);
        id->mfg_id = (addr >> 24) & GENMASK(15, 0);
        id->part_id = (addr >> 8) & GENMASK(15, 0);
        id->class_id = addr & GENMASK(7, 0);

        dev_dbg(bus->dev,
                "SDW Slave class_id %x, part_id %x, mfg_id %x, unique_id %x, version %x\n",
                                id->class_id, id->part_id, id->mfg_id,
                                id->unique_id, id->sdw_version);
}

static int sdw_program_device_num(struct sdw_bus *bus)
{
        u8 buf[SDW_NUM_DEV_ID_REGISTERS] = {0};
        struct sdw_slave *slave, *_s;
        struct sdw_slave_id id;
        struct sdw_msg msg;
        bool found = false;
        int count = 0, ret;
        u64 addr;

        /* No Slave, so use raw xfer api */
        ret = sdw_fill_msg(&msg, NULL, SDW_SCP_DEVID_0,
                           SDW_NUM_DEV_ID_REGISTERS, 0, SDW_MSG_FLAG_READ, buf);
        if (ret < 0)
                return ret;

        do {
                ret = sdw_transfer(bus, &msg);
                if (ret == -ENODATA) { /* end of device id reads */
                        dev_dbg(bus->dev, "No more devices to enumerate\n");
                        ret = 0;
                        break;
                }
                if (ret < 0) {
                        dev_err(bus->dev, "DEVID read fail:%d\n", ret);
                        break;
                }

                /*
                 * Construct the addr and extract. Cast the higher shift
                 * bits to avoid truncation due to size limit.
                 */
                addr = buf[5] | (buf[4] << 8) | (buf[3] << 16) |
                        ((u64)buf[2] << 24) | ((u64)buf[1] << 32) |
                        ((u64)buf[0] << 40);

                sdw_extract_slave_id(bus, addr, &id);

                /* Now compare with entries */
                list_for_each_entry_safe(slave, _s, &bus->slaves, node) {
                        if (sdw_compare_devid(slave, id) == 0) {
                                found = true;

                                /*
                                 * Assign a new dev_num to this Slave and
                                 * not mark it present. It will be marked
                                 * present after it reports ATTACHED on new
                                 * dev_num
                                 */
                                ret = sdw_assign_device_num(slave);
                                if (ret) {
                                        dev_err(slave->bus->dev,
                                                "Assign dev_num failed:%d\n",
                                                ret);
                                        return ret;
                                }

                                break;
                        }
                }

                if (!found) {
                        /* TODO: Park this device in Group 13 */
                        dev_err(bus->dev, "Slave Entry not found\n");
                }

                count++;

                /*
                 * Check till error out or retry (count) exhausts.
                 * Device can drop off and rejoin during enumeration
                 * so count till twice the bound.
                 */

        } while (ret == 0 && count < (SDW_MAX_DEVICES * 2));

        return ret;
}

static void sdw_modify_slave_status(struct sdw_slave *slave,
                                    enum sdw_slave_status status)
{
        mutex_lock(&slave->bus->bus_lock);
        slave->status = status;
        mutex_unlock(&slave->bus->bus_lock);
}

int sdw_configure_dpn_intr(struct sdw_slave *slave,
                           int port, bool enable, int mask)
{
        u32 addr;
        int ret;
        u8 val = 0;

        addr = SDW_DPN_INTMASK(port);

        /* Set/Clear port ready interrupt mask */
        if (enable) {
                val |= mask;
                val |= SDW_DPN_INT_PORT_READY;
        } else {
                val &= ~(mask);
                val &= ~SDW_DPN_INT_PORT_READY;
        }

        ret = sdw_update(slave, addr, (mask | SDW_DPN_INT_PORT_READY), val);
        if (ret < 0)
                dev_err(slave->bus->dev,
                        "SDW_DPN_INTMASK write failed:%d\n", val);

        return ret;
}

static int sdw_initialize_slave(struct sdw_slave *slave)
{
        struct sdw_slave_prop *prop = &slave->prop;
        int ret;
        u8 val;

        /*
         * Set bus clash, parity and SCP implementation
         * defined interrupt mask
         * TODO: Read implementation defined interrupt mask
         * from Slave property
         */
        val = SDW_SCP_INT1_IMPL_DEF | SDW_SCP_INT1_BUS_CLASH |
                                        SDW_SCP_INT1_PARITY;

        /* Enable SCP interrupts */
        ret = sdw_update(slave, SDW_SCP_INTMASK1, val, val);
        if (ret < 0) {
                dev_err(slave->bus->dev,
                        "SDW_SCP_INTMASK1 write failed:%d\n", ret);
                return ret;
        }

        /* No need to continue if DP0 is not present */
        if (!slave->prop.dp0_prop)
                return 0;

        /* Enable DP0 interrupts */
        val = prop->dp0_prop->imp_def_interrupts;
        val |= SDW_DP0_INT_PORT_READY | SDW_DP0_INT_BRA_FAILURE;

        ret = sdw_update(slave, SDW_DP0_INTMASK, val, val);
        if (ret < 0) {
                dev_err(slave->bus->dev,
                        "SDW_DP0_INTMASK read failed:%d\n", ret);
                return val;
        }

        return 0;
}

static int sdw_handle_dp0_interrupt(struct sdw_slave *slave, u8 *slave_status)
{
        u8 clear = 0, impl_int_mask;
        int status, status2, ret, count = 0;

        status = sdw_read(slave, SDW_DP0_INT);
        if (status < 0) {
                dev_err(slave->bus->dev,
                        "SDW_DP0_INT read failed:%d\n", status);
                return status;
        }

        do {
                if (status & SDW_DP0_INT_TEST_FAIL) {
                        dev_err(&slave->dev, "Test fail for port 0\n");
                        clear |= SDW_DP0_INT_TEST_FAIL;
                }

                /*
                 * Assumption: PORT_READY interrupt will be received only for
                 * ports implementing Channel Prepare state machine (CP_SM)
                 */

                if (status & SDW_DP0_INT_PORT_READY) {
                        complete(&slave->port_ready[0]);
                        clear |= SDW_DP0_INT_PORT_READY;
                }

                if (status & SDW_DP0_INT_BRA_FAILURE) {
                        dev_err(&slave->dev, "BRA failed\n");
                        clear |= SDW_DP0_INT_BRA_FAILURE;
                }

                impl_int_mask = SDW_DP0_INT_IMPDEF1 |
                        SDW_DP0_INT_IMPDEF2 | SDW_DP0_INT_IMPDEF3;

                if (status & impl_int_mask) {
                        clear |= impl_int_mask;
                        *slave_status = clear;
                }

                /* clear the interrupt */
                ret = sdw_write(slave, SDW_DP0_INT, clear);
                if (ret < 0) {
                        dev_err(slave->bus->dev,
                                "SDW_DP0_INT write failed:%d\n", ret);
                        return ret;
                }

                /* Read DP0 interrupt again */
                status2 = sdw_read(slave, SDW_DP0_INT);
                if (status2 < 0) {
                        dev_err(slave->bus->dev,
                                "SDW_DP0_INT read failed:%d\n", status2);
                        return status2;
                }
                status &= status2;

                count++;

                /* we can get alerts while processing so keep retrying */
        } while (status != 0 && count < SDW_READ_INTR_CLEAR_RETRY);

        if (count == SDW_READ_INTR_CLEAR_RETRY)
                dev_warn(slave->bus->dev, "Reached MAX_RETRY on DP0 read\n");

        return ret;
}

static int sdw_handle_port_interrupt(struct sdw_slave *slave,
                                     int port, u8 *slave_status)
{
        u8 clear = 0, impl_int_mask;
        int status, status2, ret, count = 0;
        u32 addr;

        if (port == 0)
                return sdw_handle_dp0_interrupt(slave, slave_status);

        addr = SDW_DPN_INT(port);
        status = sdw_read(slave, addr);
        if (status < 0) {
                dev_err(slave->bus->dev,
                        "SDW_DPN_INT read failed:%d\n", status);

                return status;
        }

        do {
                if (status & SDW_DPN_INT_TEST_FAIL) {
                        dev_err(&slave->dev, "Test fail for port:%d\n", port);
                        clear |= SDW_DPN_INT_TEST_FAIL;
                }

                /*
                 * Assumption: PORT_READY interrupt will be received only
                 * for ports implementing CP_SM.
                 */
                if (status & SDW_DPN_INT_PORT_READY) {
                        complete(&slave->port_ready[port]);
                        clear |= SDW_DPN_INT_PORT_READY;
                }

                impl_int_mask = SDW_DPN_INT_IMPDEF1 |
                        SDW_DPN_INT_IMPDEF2 | SDW_DPN_INT_IMPDEF3;

                if (status & impl_int_mask) {
                        clear |= impl_int_mask;
                        *slave_status = clear;
                }

                /* clear the interrupt */
                ret = sdw_write(slave, addr, clear);
                if (ret < 0) {
                        dev_err(slave->bus->dev,
                                "SDW_DPN_INT write failed:%d\n", ret);
                        return ret;
                }

                /* Read DPN interrupt again */
                status2 = sdw_read(slave, addr);
                if (status2 < 0) {
                        dev_err(slave->bus->dev,
                                "SDW_DPN_INT read failed:%d\n", status2);
                        return status2;
                }
                status &= status2;

                count++;

                /* we can get alerts while processing so keep retrying */
        } while (status != 0 && count < SDW_READ_INTR_CLEAR_RETRY);

        if (count == SDW_READ_INTR_CLEAR_RETRY)
                dev_warn(slave->bus->dev, "Reached MAX_RETRY on port read");

        return ret;
}

static int sdw_handle_slave_alerts(struct sdw_slave *slave)
{
        struct sdw_slave_intr_status slave_intr;
        u8 clear = 0, bit, port_status[15] = {0};
        int port_num, stat, ret, count = 0;
        unsigned long port;
        bool slave_notify = false;
        u8 buf, buf2[2], _buf, _buf2[2];

        sdw_modify_slave_status(slave, SDW_SLAVE_ALERT);

        /* Read Instat 1, Instat 2 and Instat 3 registers */
        ret = sdw_read(slave, SDW_SCP_INT1);
        if (ret < 0) {
                dev_err(slave->bus->dev,
                        "SDW_SCP_INT1 read failed:%d\n", ret);
                return ret;
        }
        buf = ret;

        ret = sdw_nread(slave, SDW_SCP_INTSTAT2, 2, buf2);
        if (ret < 0) {
                dev_err(slave->bus->dev,
                        "SDW_SCP_INT2/3 read failed:%d\n", ret);
                return ret;
        }

        do {
                /*
                 * Check parity, bus clash and Slave (impl defined)
                 * interrupt
                 */
                if (buf & SDW_SCP_INT1_PARITY) {
                        dev_err(&slave->dev, "Parity error detected\n");
                        clear |= SDW_SCP_INT1_PARITY;
                }

                if (buf & SDW_SCP_INT1_BUS_CLASH) {
                        dev_err(&slave->dev, "Bus clash error detected\n");
                        clear |= SDW_SCP_INT1_BUS_CLASH;
                }

                /*
                 * When bus clash or parity errors are detected, such errors
                 * are unlikely to be recoverable errors.
                 * TODO: In such scenario, reset bus. Make this configurable
                 * via sysfs property with bus reset being the default.
                 */

                if (buf & SDW_SCP_INT1_IMPL_DEF) {
                        dev_dbg(&slave->dev, "Slave impl defined interrupt\n");
                        clear |= SDW_SCP_INT1_IMPL_DEF;
                        slave_notify = true;
                }

                /* Check port 0 - 3 interrupts */
                port = buf & SDW_SCP_INT1_PORT0_3;

                /* To get port number corresponding to bits, shift it */
                port = port >> SDW_REG_SHIFT(SDW_SCP_INT1_PORT0_3);
                for_each_set_bit(bit, &port, 8) {
                        sdw_handle_port_interrupt(slave, bit,
                                                  &port_status[bit]);
                }

                /* Check if cascade 2 interrupt is present */
                if (buf & SDW_SCP_INT1_SCP2_CASCADE) {
                        port = buf2[0] & SDW_SCP_INTSTAT2_PORT4_10;
                        for_each_set_bit(bit, &port, 8) {
                                /* scp2 ports start from 4 */
                                port_num = bit + 3;
                                sdw_handle_port_interrupt(slave,
                                                port_num,
                                                &port_status[port_num]);
                        }
                }

                /* now check last cascade */
                if (buf2[0] & SDW_SCP_INTSTAT2_SCP3_CASCADE) {
                        port = buf2[1] & SDW_SCP_INTSTAT3_PORT11_14;
                        for_each_set_bit(bit, &port, 8) {
                                /* scp3 ports start from 11 */
                                port_num = bit + 10;
                                sdw_handle_port_interrupt(slave,
                                                port_num,
                                                &port_status[port_num]);
                        }
                }

                /* Update the Slave driver */
                if (slave_notify && slave->ops &&
                    slave->ops->interrupt_callback) {
                        slave_intr.control_port = clear;
                        memcpy(slave_intr.port, &port_status,
                               sizeof(slave_intr.port));

                        slave->ops->interrupt_callback(slave, &slave_intr);
                }

                /* Ack interrupt */
                ret = sdw_write(slave, SDW_SCP_INT1, clear);
                if (ret < 0) {
                        dev_err(slave->bus->dev,
                                "SDW_SCP_INT1 write failed:%d\n", ret);
                        return ret;
                }

                /*
                 * Read status again to ensure no new interrupts arrived
                 * while servicing interrupts.
                 */
                ret = sdw_read(slave, SDW_SCP_INT1);
                if (ret < 0) {
                        dev_err(slave->bus->dev,
                                "SDW_SCP_INT1 read failed:%d\n", ret);
                        return ret;
                }
                _buf = ret;

                ret = sdw_nread(slave, SDW_SCP_INTSTAT2, 2, _buf2);
                if (ret < 0) {
                        dev_err(slave->bus->dev,
                                "SDW_SCP_INT2/3 read failed:%d\n", ret);
                        return ret;
                }

                /* Make sure no interrupts are pending */
                buf &= _buf;
                buf2[0] &= _buf2[0];
                buf2[1] &= _buf2[1];
                stat = buf || buf2[0] || buf2[1];

                /*
                 * Exit loop if Slave is continuously in ALERT state even
                 * after servicing the interrupt multiple times.
                 */
                count++;

                /* we can get alerts while processing so keep retrying */
        } while (stat != 0 && count < SDW_READ_INTR_CLEAR_RETRY);

        if (count == SDW_READ_INTR_CLEAR_RETRY)
                dev_warn(slave->bus->dev, "Reached MAX_RETRY on alert read\n");

        return ret;
}

static int sdw_update_slave_status(struct sdw_slave *slave,
                                   enum sdw_slave_status status)
{
        if (slave->ops && slave->ops->update_status)
                return slave->ops->update_status(slave, status);

        return 0;
}

/**
 * sdw_handle_slave_status() - Handle Slave status
 * @bus: SDW bus instance
 * @status: Status for all Slave(s)
 */
int sdw_handle_slave_status(struct sdw_bus *bus,
                            enum sdw_slave_status status[])
{
        enum sdw_slave_status prev_status;
        struct sdw_slave *slave;
        int i, ret = 0;

        /* first check if any Slaves fell off the bus */
        for (i = 1; i <= SDW_MAX_DEVICES; i++) {
                mutex_lock(&bus->bus_lock);
                if (test_bit(i, bus->assigned) == false) {
                        mutex_unlock(&bus->bus_lock);
                        continue;
                }
                mutex_unlock(&bus->bus_lock);

                slave = sdw_get_slave(bus, i);
                if (!slave)
                        continue;

                if (status[i] == SDW_SLAVE_UNATTACHED &&
                    slave->status != SDW_SLAVE_UNATTACHED)
                        sdw_modify_slave_status(slave, SDW_SLAVE_UNATTACHED);
        }

        if (status[0] == SDW_SLAVE_ATTACHED) {
                dev_dbg(bus->dev, "Slave attached, programming device number\n");
                ret = sdw_program_device_num(bus);
                if (ret)
                        dev_err(bus->dev, "Slave attach failed: %d\n", ret);
                /*
                 * programming a device number will have side effects,
                 * so we deal with other devices at a later time
                 */
                return ret;
        }

        /* Continue to check other slave statuses */
        for (i = 1; i <= SDW_MAX_DEVICES; i++) {
                mutex_lock(&bus->bus_lock);
                if (test_bit(i, bus->assigned) == false) {
                        mutex_unlock(&bus->bus_lock);
                        continue;
                }
                mutex_unlock(&bus->bus_lock);

                slave = sdw_get_slave(bus, i);
                if (!slave)
                        continue;

                switch (status[i]) {
                case SDW_SLAVE_UNATTACHED:
                        if (slave->status == SDW_SLAVE_UNATTACHED)
                                break;

                        sdw_modify_slave_status(slave, SDW_SLAVE_UNATTACHED);
                        break;

                case SDW_SLAVE_ALERT:
                        ret = sdw_handle_slave_alerts(slave);
                        if (ret)
                                dev_err(bus->dev,
                                        "Slave %d alert handling failed: %d\n",
                                        i, ret);
                        break;

                case SDW_SLAVE_ATTACHED:
                        if (slave->status == SDW_SLAVE_ATTACHED)
                                break;

                        prev_status = slave->status;
                        sdw_modify_slave_status(slave, SDW_SLAVE_ATTACHED);

                        if (prev_status == SDW_SLAVE_ALERT)
                                break;

                        ret = sdw_initialize_slave(slave);
                        if (ret)
                                dev_err(bus->dev,
                                        "Slave %d initialization failed: %d\n",
                                        i, ret);

                        break;

                default:
                        dev_err(bus->dev, "Invalid slave %d status:%d\n",
                                i, status[i]);
                        break;
                }

                ret = sdw_update_slave_status(slave, status[i]);
                if (ret)
                        dev_err(slave->bus->dev,
                                "Update Slave status failed:%d\n", ret);
        }

        return ret;
}
EXPORT_SYMBOL(sdw_handle_slave_status);