treewide: remove redundant IS_ERR() before error code check

[linux/fpc-iii.git] / drivers / acpi / acpi_lpss.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * ACPI support for Intel Lynxpoint LPSS.
 *
 * Copyright (C) 2013, Intel Corporation
 * Authors: Mika Westerberg <mika.westerberg@linux.intel.com>
 *          Rafael J. Wysocki <rafael.j.wysocki@intel.com>
 */

#include <linux/acpi.h>
#include <linux/clkdev.h>
#include <linux/clk-provider.h>
#include <linux/dmi.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/platform_device.h>
#include <linux/platform_data/x86/clk-lpss.h>
#include <linux/platform_data/x86/pmc_atom.h>
#include <linux/pm_domain.h>
#include <linux/pm_runtime.h>
#include <linux/pwm.h>
#include <linux/suspend.h>
#include <linux/delay.h>

#include "internal.h"

ACPI_MODULE_NAME("acpi_lpss");

#ifdef CONFIG_X86_INTEL_LPSS

#include <asm/cpu_device_id.h>
#include <asm/intel-family.h>
#include <asm/iosf_mbi.h>

#define LPSS_ADDR(desc) ((unsigned long)&desc)

#define LPSS_CLK_SIZE   0x04
#define LPSS_LTR_SIZE   0x18

/* Offsets relative to LPSS_PRIVATE_OFFSET */
#define LPSS_CLK_DIVIDER_DEF_MASK       (BIT(1) | BIT(16))
#define LPSS_RESETS                     0x04
#define LPSS_RESETS_RESET_FUNC          BIT(0)
#define LPSS_RESETS_RESET_APB           BIT(1)
#define LPSS_GENERAL                    0x08
#define LPSS_GENERAL_LTR_MODE_SW        BIT(2)
#define LPSS_GENERAL_UART_RTS_OVRD      BIT(3)
#define LPSS_SW_LTR                     0x10
#define LPSS_AUTO_LTR                   0x14
#define LPSS_LTR_SNOOP_REQ              BIT(15)
#define LPSS_LTR_SNOOP_MASK             0x0000FFFF
#define LPSS_LTR_SNOOP_LAT_1US          0x800
#define LPSS_LTR_SNOOP_LAT_32US         0xC00
#define LPSS_LTR_SNOOP_LAT_SHIFT        5
#define LPSS_LTR_SNOOP_LAT_CUTOFF       3000
#define LPSS_LTR_MAX_VAL                0x3FF
#define LPSS_TX_INT                     0x20
#define LPSS_TX_INT_MASK                BIT(1)

#define LPSS_PRV_REG_COUNT              9

/* LPSS Flags */
#define LPSS_CLK                        BIT(0)
#define LPSS_CLK_GATE                   BIT(1)
#define LPSS_CLK_DIVIDER                BIT(2)
#define LPSS_LTR                        BIT(3)
#define LPSS_SAVE_CTX                   BIT(4)
#define LPSS_NO_D3_DELAY                BIT(5)

struct lpss_private_data;

struct lpss_device_desc {
        unsigned int flags;
        const char *clk_con_id;
        unsigned int prv_offset;
        size_t prv_size_override;
        struct property_entry *properties;
        void (*setup)(struct lpss_private_data *pdata);
        bool resume_from_noirq;
};

static const struct lpss_device_desc lpss_dma_desc = {
        .flags = LPSS_CLK,
};

struct lpss_private_data {
        struct acpi_device *adev;
        void __iomem *mmio_base;
        resource_size_t mmio_size;
        unsigned int fixed_clk_rate;
        struct clk *clk;
        const struct lpss_device_desc *dev_desc;
        u32 prv_reg_ctx[LPSS_PRV_REG_COUNT];
};

/* Devices which need to be in D3 before lpss_iosf_enter_d3_state() proceeds */
static u32 pmc_atom_d3_mask = 0xfe000ffe;

/* LPSS run time quirks */
static unsigned int lpss_quirks;

/*
 * LPSS_QUIRK_ALWAYS_POWER_ON: override power state for LPSS DMA device.
 *
 * The LPSS DMA controller has neither _PS0 nor _PS3 method. Moreover
 * it can be powered off automatically whenever the last LPSS device goes down.
 * In case of no power any access to the DMA controller will hang the system.
 * The behaviour is reproduced on some HP laptops based on Intel BayTrail as
 * well as on ASuS T100TA transformer.
 *
 * This quirk overrides power state of entire LPSS island to keep DMA powered
 * on whenever we have at least one other device in use.
 */
#define LPSS_QUIRK_ALWAYS_POWER_ON      BIT(0)

/* UART Component Parameter Register */
#define LPSS_UART_CPR                   0xF4
#define LPSS_UART_CPR_AFCE              BIT(4)

static void lpss_uart_setup(struct lpss_private_data *pdata)
{
        unsigned int offset;
        u32 val;

        offset = pdata->dev_desc->prv_offset + LPSS_TX_INT;
        val = readl(pdata->mmio_base + offset);
        writel(val | LPSS_TX_INT_MASK, pdata->mmio_base + offset);

        val = readl(pdata->mmio_base + LPSS_UART_CPR);
        if (!(val & LPSS_UART_CPR_AFCE)) {
                offset = pdata->dev_desc->prv_offset + LPSS_GENERAL;
                val = readl(pdata->mmio_base + offset);
                val |= LPSS_GENERAL_UART_RTS_OVRD;
                writel(val, pdata->mmio_base + offset);
        }
}

static void lpss_deassert_reset(struct lpss_private_data *pdata)
{
        unsigned int offset;
        u32 val;

        offset = pdata->dev_desc->prv_offset + LPSS_RESETS;
        val = readl(pdata->mmio_base + offset);
        val |= LPSS_RESETS_RESET_APB | LPSS_RESETS_RESET_FUNC;
        writel(val, pdata->mmio_base + offset);
}

/*
 * BYT PWM used for backlight control by the i915 driver on systems without
 * the Crystal Cove PMIC.
 */
static struct pwm_lookup byt_pwm_lookup[] = {
        PWM_LOOKUP_WITH_MODULE("80860F09:00", 0, "0000:00:02.0",
                               "pwm_soc_backlight", 0, PWM_POLARITY_NORMAL,
                               "pwm-lpss-platform"),
};

static void byt_pwm_setup(struct lpss_private_data *pdata)
{
        struct acpi_device *adev = pdata->adev;

        /* Only call pwm_add_table for the first PWM controller */
        if (!adev->pnp.unique_id || strcmp(adev->pnp.unique_id, "1"))
                return;

        pwm_add_table(byt_pwm_lookup, ARRAY_SIZE(byt_pwm_lookup));
}

#define LPSS_I2C_ENABLE                 0x6c

static void byt_i2c_setup(struct lpss_private_data *pdata)
{
        const char *uid_str = acpi_device_uid(pdata->adev);
        acpi_handle handle = pdata->adev->handle;
        unsigned long long shared_host = 0;
        acpi_status status;
        long uid = 0;

        /* Expected to always be true, but better safe then sorry */
        if (uid_str)
                uid = simple_strtol(uid_str, NULL, 10);

        /* Detect I2C bus shared with PUNIT and ignore its d3 status */
        status = acpi_evaluate_integer(handle, "_SEM", NULL, &shared_host);
        if (ACPI_SUCCESS(status) && shared_host && uid)
                pmc_atom_d3_mask &= ~(BIT_LPSS2_F1_I2C1 << (uid - 1));

        lpss_deassert_reset(pdata);

        if (readl(pdata->mmio_base + pdata->dev_desc->prv_offset))
                pdata->fixed_clk_rate = 133000000;

        writel(0, pdata->mmio_base + LPSS_I2C_ENABLE);
}

/* BSW PWM used for backlight control by the i915 driver */
static struct pwm_lookup bsw_pwm_lookup[] = {
        PWM_LOOKUP_WITH_MODULE("80862288:00", 0, "0000:00:02.0",
                               "pwm_soc_backlight", 0, PWM_POLARITY_NORMAL,
                               "pwm-lpss-platform"),
};

static void bsw_pwm_setup(struct lpss_private_data *pdata)
{
        struct acpi_device *adev = pdata->adev;

        /* Only call pwm_add_table for the first PWM controller */
        if (!adev->pnp.unique_id || strcmp(adev->pnp.unique_id, "1"))
                return;

        pwm_add_table(bsw_pwm_lookup, ARRAY_SIZE(bsw_pwm_lookup));
}

static const struct lpss_device_desc lpt_dev_desc = {
        .flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_LTR
                        | LPSS_SAVE_CTX,
        .prv_offset = 0x800,
};

static const struct lpss_device_desc lpt_i2c_dev_desc = {
        .flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_LTR | LPSS_SAVE_CTX,
        .prv_offset = 0x800,
};

static struct property_entry uart_properties[] = {
        PROPERTY_ENTRY_U32("reg-io-width", 4),
        PROPERTY_ENTRY_U32("reg-shift", 2),
        PROPERTY_ENTRY_BOOL("snps,uart-16550-compatible"),
        { },
};

static const struct lpss_device_desc lpt_uart_dev_desc = {
        .flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_LTR
                        | LPSS_SAVE_CTX,
        .clk_con_id = "baudclk",
        .prv_offset = 0x800,
        .setup = lpss_uart_setup,
        .properties = uart_properties,
};

static const struct lpss_device_desc lpt_sdio_dev_desc = {
        .flags = LPSS_LTR,
        .prv_offset = 0x1000,
        .prv_size_override = 0x1018,
};

static const struct lpss_device_desc byt_pwm_dev_desc = {
        .flags = LPSS_SAVE_CTX,
        .prv_offset = 0x800,
        .setup = byt_pwm_setup,
};

static const struct lpss_device_desc bsw_pwm_dev_desc = {
        .flags = LPSS_SAVE_CTX | LPSS_NO_D3_DELAY,
        .prv_offset = 0x800,
        .setup = bsw_pwm_setup,
};

static const struct lpss_device_desc byt_uart_dev_desc = {
        .flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_SAVE_CTX,
        .clk_con_id = "baudclk",
        .prv_offset = 0x800,
        .setup = lpss_uart_setup,
        .properties = uart_properties,
};

static const struct lpss_device_desc bsw_uart_dev_desc = {
        .flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_SAVE_CTX
                        | LPSS_NO_D3_DELAY,
        .clk_con_id = "baudclk",
        .prv_offset = 0x800,
        .setup = lpss_uart_setup,
        .properties = uart_properties,
};

static const struct lpss_device_desc byt_spi_dev_desc = {
        .flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_SAVE_CTX,
        .prv_offset = 0x400,
};

static const struct lpss_device_desc byt_sdio_dev_desc = {
        .flags = LPSS_CLK,
};

static const struct lpss_device_desc byt_i2c_dev_desc = {
        .flags = LPSS_CLK | LPSS_SAVE_CTX,
        .prv_offset = 0x800,
        .setup = byt_i2c_setup,
        .resume_from_noirq = true,
};

static const struct lpss_device_desc bsw_i2c_dev_desc = {
        .flags = LPSS_CLK | LPSS_SAVE_CTX | LPSS_NO_D3_DELAY,
        .prv_offset = 0x800,
        .setup = byt_i2c_setup,
        .resume_from_noirq = true,
};

static const struct lpss_device_desc bsw_spi_dev_desc = {
        .flags = LPSS_CLK | LPSS_CLK_GATE | LPSS_CLK_DIVIDER | LPSS_SAVE_CTX
                        | LPSS_NO_D3_DELAY,
        .prv_offset = 0x400,
        .setup = lpss_deassert_reset,
};

#define ICPU(model)     { X86_VENDOR_INTEL, 6, model, X86_FEATURE_ANY, }

static const struct x86_cpu_id lpss_cpu_ids[] = {
        ICPU(INTEL_FAM6_ATOM_SILVERMONT),       /* Valleyview, Bay Trail */
        ICPU(INTEL_FAM6_ATOM_AIRMONT),  /* Braswell, Cherry Trail */
        {}
};

#else

#define LPSS_ADDR(desc) (0UL)

#endif /* CONFIG_X86_INTEL_LPSS */

static const struct acpi_device_id acpi_lpss_device_ids[] = {
        /* Generic LPSS devices */
        { "INTL9C60", LPSS_ADDR(lpss_dma_desc) },

        /* Lynxpoint LPSS devices */
        { "INT33C0", LPSS_ADDR(lpt_dev_desc) },
        { "INT33C1", LPSS_ADDR(lpt_dev_desc) },
        { "INT33C2", LPSS_ADDR(lpt_i2c_dev_desc) },
        { "INT33C3", LPSS_ADDR(lpt_i2c_dev_desc) },
        { "INT33C4", LPSS_ADDR(lpt_uart_dev_desc) },
        { "INT33C5", LPSS_ADDR(lpt_uart_dev_desc) },
        { "INT33C6", LPSS_ADDR(lpt_sdio_dev_desc) },
        { "INT33C7", },

        /* BayTrail LPSS devices */
        { "80860F09", LPSS_ADDR(byt_pwm_dev_desc) },
        { "80860F0A", LPSS_ADDR(byt_uart_dev_desc) },
        { "80860F0E", LPSS_ADDR(byt_spi_dev_desc) },
        { "80860F14", LPSS_ADDR(byt_sdio_dev_desc) },
        { "80860F41", LPSS_ADDR(byt_i2c_dev_desc) },
        { "INT33B2", },
        { "INT33FC", },

        /* Braswell LPSS devices */
        { "80862286", LPSS_ADDR(lpss_dma_desc) },
        { "80862288", LPSS_ADDR(bsw_pwm_dev_desc) },
        { "8086228A", LPSS_ADDR(bsw_uart_dev_desc) },
        { "8086228E", LPSS_ADDR(bsw_spi_dev_desc) },
        { "808622C0", LPSS_ADDR(lpss_dma_desc) },
        { "808622C1", LPSS_ADDR(bsw_i2c_dev_desc) },

        /* Broadwell LPSS devices */
        { "INT3430", LPSS_ADDR(lpt_dev_desc) },
        { "INT3431", LPSS_ADDR(lpt_dev_desc) },
        { "INT3432", LPSS_ADDR(lpt_i2c_dev_desc) },
        { "INT3433", LPSS_ADDR(lpt_i2c_dev_desc) },
        { "INT3434", LPSS_ADDR(lpt_uart_dev_desc) },
        { "INT3435", LPSS_ADDR(lpt_uart_dev_desc) },
        { "INT3436", LPSS_ADDR(lpt_sdio_dev_desc) },
        { "INT3437", },

        /* Wildcat Point LPSS devices */
        { "INT3438", LPSS_ADDR(lpt_dev_desc) },

        { }
};

#ifdef CONFIG_X86_INTEL_LPSS

static int is_memory(struct acpi_resource *res, void *not_used)
{
        struct resource r;
        return !acpi_dev_resource_memory(res, &r);
}

/* LPSS main clock device. */
static struct platform_device *lpss_clk_dev;

static inline void lpt_register_clock_device(void)
{
        lpss_clk_dev = platform_device_register_simple("clk-lpt", -1, NULL, 0);
}

static int register_device_clock(struct acpi_device *adev,
                                 struct lpss_private_data *pdata)
{
        const struct lpss_device_desc *dev_desc = pdata->dev_desc;
        const char *devname = dev_name(&adev->dev);
        struct clk *clk;
        struct lpss_clk_data *clk_data;
        const char *parent, *clk_name;
        void __iomem *prv_base;

        if (!lpss_clk_dev)
                lpt_register_clock_device();

        clk_data = platform_get_drvdata(lpss_clk_dev);
        if (!clk_data)
                return -ENODEV;
        clk = clk_data->clk;

        if (!pdata->mmio_base
            || pdata->mmio_size < dev_desc->prv_offset + LPSS_CLK_SIZE)
                return -ENODATA;

        parent = clk_data->name;
        prv_base = pdata->mmio_base + dev_desc->prv_offset;

        if (pdata->fixed_clk_rate) {
                clk = clk_register_fixed_rate(NULL, devname, parent, 0,
                                              pdata->fixed_clk_rate);
                goto out;
        }

        if (dev_desc->flags & LPSS_CLK_GATE) {
                clk = clk_register_gate(NULL, devname, parent, 0,
                                        prv_base, 0, 0, NULL);
                parent = devname;
        }

        if (dev_desc->flags & LPSS_CLK_DIVIDER) {
                /* Prevent division by zero */
                if (!readl(prv_base))
                        writel(LPSS_CLK_DIVIDER_DEF_MASK, prv_base);

                clk_name = kasprintf(GFP_KERNEL, "%s-div", devname);
                if (!clk_name)
                        return -ENOMEM;
                clk = clk_register_fractional_divider(NULL, clk_name, parent,
                                                      0, prv_base,
                                                      1, 15, 16, 15, 0, NULL);
                parent = clk_name;

                clk_name = kasprintf(GFP_KERNEL, "%s-update", devname);
                if (!clk_name) {
                        kfree(parent);
                        return -ENOMEM;
                }
                clk = clk_register_gate(NULL, clk_name, parent,
                                        CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE,
                                        prv_base, 31, 0, NULL);
                kfree(parent);
                kfree(clk_name);
        }
out:
        if (IS_ERR(clk))
                return PTR_ERR(clk);

        pdata->clk = clk;
        clk_register_clkdev(clk, dev_desc->clk_con_id, devname);
        return 0;
}

struct lpss_device_links {
        const char *supplier_hid;
        const char *supplier_uid;
        const char *consumer_hid;
        const char *consumer_uid;
        u32 flags;
        const struct dmi_system_id *dep_missing_ids;
};

/* Please keep this list sorted alphabetically by vendor and model */
static const struct dmi_system_id i2c1_dep_missing_dmi_ids[] = {
        {
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "T200TA"),
                },
        },
        {}
};

/*
 * The _DEP method is used to identify dependencies but instead of creating
 * device links for every handle in _DEP, only links in the following list are
 * created. That is necessary because, in the general case, _DEP can refer to
 * devices that might not have drivers, or that are on different buses, or where
 * the supplier is not enumerated until after the consumer is probed.
 */
static const struct lpss_device_links lpss_device_links[] = {
        /* CHT External sdcard slot controller depends on PMIC I2C ctrl */
        {"808622C1", "7", "80860F14", "3", DL_FLAG_PM_RUNTIME},
        /* CHT iGPU depends on PMIC I2C controller */
        {"808622C1", "7", "LNXVIDEO", NULL, DL_FLAG_PM_RUNTIME},
        /* BYT iGPU depends on the Embedded Controller I2C controller (UID 1) */
        {"80860F41", "1", "LNXVIDEO", NULL, DL_FLAG_PM_RUNTIME,
         i2c1_dep_missing_dmi_ids},
        /* BYT CR iGPU depends on PMIC I2C controller (UID 5 on CR) */
        {"80860F41", "5", "LNXVIDEO", NULL, DL_FLAG_PM_RUNTIME},
        /* BYT iGPU depends on PMIC I2C controller (UID 7 on non CR) */
        {"80860F41", "7", "LNXVIDEO", NULL, DL_FLAG_PM_RUNTIME},
};

static bool acpi_lpss_is_supplier(struct acpi_device *adev,
                                  const struct lpss_device_links *link)
{
        return acpi_dev_hid_uid_match(adev, link->supplier_hid, link->supplier_uid);
}

static bool acpi_lpss_is_consumer(struct acpi_device *adev,
                                  const struct lpss_device_links *link)
{
        return acpi_dev_hid_uid_match(adev, link->consumer_hid, link->consumer_uid);
}

struct hid_uid {
        const char *hid;
        const char *uid;
};

static int match_hid_uid(struct device *dev, const void *data)
{
        struct acpi_device *adev = ACPI_COMPANION(dev);
        const struct hid_uid *id = data;

        if (!adev)
                return 0;

        return acpi_dev_hid_uid_match(adev, id->hid, id->uid);
}

static struct device *acpi_lpss_find_device(const char *hid, const char *uid)
{
        struct device *dev;

        struct hid_uid data = {
                .hid = hid,
                .uid = uid,
        };

        dev = bus_find_device(&platform_bus_type, NULL, &data, match_hid_uid);
        if (dev)
                return dev;

        return bus_find_device(&pci_bus_type, NULL, &data, match_hid_uid);
}

static bool acpi_lpss_dep(struct acpi_device *adev, acpi_handle handle)
{
        struct acpi_handle_list dep_devices;
        acpi_status status;
        int i;

        if (!acpi_has_method(adev->handle, "_DEP"))
                return false;

        status = acpi_evaluate_reference(adev->handle, "_DEP", NULL,
                                         &dep_devices);
        if (ACPI_FAILURE(status)) {
                dev_dbg(&adev->dev, "Failed to evaluate _DEP.\n");
                return false;
        }

        for (i = 0; i < dep_devices.count; i++) {
                if (dep_devices.handles[i] == handle)
                        return true;
        }

        return false;
}

static void acpi_lpss_link_consumer(struct device *dev1,
                                    const struct lpss_device_links *link)
{
        struct device *dev2;

        dev2 = acpi_lpss_find_device(link->consumer_hid, link->consumer_uid);
        if (!dev2)
                return;

        if ((link->dep_missing_ids && dmi_check_system(link->dep_missing_ids))
            || acpi_lpss_dep(ACPI_COMPANION(dev2), ACPI_HANDLE(dev1)))
                device_link_add(dev2, dev1, link->flags);

        put_device(dev2);
}

static void acpi_lpss_link_supplier(struct device *dev1,
                                    const struct lpss_device_links *link)
{
        struct device *dev2;

        dev2 = acpi_lpss_find_device(link->supplier_hid, link->supplier_uid);
        if (!dev2)
                return;

        if ((link->dep_missing_ids && dmi_check_system(link->dep_missing_ids))
            || acpi_lpss_dep(ACPI_COMPANION(dev1), ACPI_HANDLE(dev2)))
                device_link_add(dev1, dev2, link->flags);

        put_device(dev2);
}

static void acpi_lpss_create_device_links(struct acpi_device *adev,
                                          struct platform_device *pdev)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(lpss_device_links); i++) {
                const struct lpss_device_links *link = &lpss_device_links[i];

                if (acpi_lpss_is_supplier(adev, link))
                        acpi_lpss_link_consumer(&pdev->dev, link);

                if (acpi_lpss_is_consumer(adev, link))
                        acpi_lpss_link_supplier(&pdev->dev, link);
        }
}

static int acpi_lpss_create_device(struct acpi_device *adev,
                                   const struct acpi_device_id *id)
{
        const struct lpss_device_desc *dev_desc;
        struct lpss_private_data *pdata;
        struct resource_entry *rentry;
        struct list_head resource_list;
        struct platform_device *pdev;
        int ret;

        dev_desc = (const struct lpss_device_desc *)id->driver_data;
        if (!dev_desc) {
                pdev = acpi_create_platform_device(adev, NULL);
                return IS_ERR_OR_NULL(pdev) ? PTR_ERR(pdev) : 1;
        }
        pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
        if (!pdata)
                return -ENOMEM;

        INIT_LIST_HEAD(&resource_list);
        ret = acpi_dev_get_resources(adev, &resource_list, is_memory, NULL);
        if (ret < 0)
                goto err_out;

        list_for_each_entry(rentry, &resource_list, node)
                if (resource_type(rentry->res) == IORESOURCE_MEM) {
                        if (dev_desc->prv_size_override)
                                pdata->mmio_size = dev_desc->prv_size_override;
                        else
                                pdata->mmio_size = resource_size(rentry->res);
                        pdata->mmio_base = ioremap(rentry->res->start,
                                                   pdata->mmio_size);
                        break;
                }

        acpi_dev_free_resource_list(&resource_list);

        if (!pdata->mmio_base) {
                /* Avoid acpi_bus_attach() instantiating a pdev for this dev. */
                adev->pnp.type.platform_id = 0;
                /* Skip the device, but continue the namespace scan. */
                ret = 0;
                goto err_out;
        }

        pdata->adev = adev;
        pdata->dev_desc = dev_desc;

        if (dev_desc->setup)
                dev_desc->setup(pdata);

        if (dev_desc->flags & LPSS_CLK) {
                ret = register_device_clock(adev, pdata);
                if (ret) {
                        /* Skip the device, but continue the namespace scan. */
                        ret = 0;
                        goto err_out;
                }
        }

        /*
         * This works around a known issue in ACPI tables where LPSS devices
         * have _PS0 and _PS3 without _PSC (and no power resources), so
         * acpi_bus_init_power() will assume that the BIOS has put them into D0.
         */
        acpi_device_fix_up_power(adev);

        adev->driver_data = pdata;
        pdev = acpi_create_platform_device(adev, dev_desc->properties);
        if (!IS_ERR_OR_NULL(pdev)) {
                acpi_lpss_create_device_links(adev, pdev);
                return 1;
        }

        ret = PTR_ERR(pdev);
        adev->driver_data = NULL;

 err_out:
        kfree(pdata);
        return ret;
}

static u32 __lpss_reg_read(struct lpss_private_data *pdata, unsigned int reg)
{
        return readl(pdata->mmio_base + pdata->dev_desc->prv_offset + reg);
}

static void __lpss_reg_write(u32 val, struct lpss_private_data *pdata,
                             unsigned int reg)
{
        writel(val, pdata->mmio_base + pdata->dev_desc->prv_offset + reg);
}

static int lpss_reg_read(struct device *dev, unsigned int reg, u32 *val)
{
        struct acpi_device *adev;
        struct lpss_private_data *pdata;
        unsigned long flags;
        int ret;

        ret = acpi_bus_get_device(ACPI_HANDLE(dev), &adev);
        if (WARN_ON(ret))
                return ret;

        spin_lock_irqsave(&dev->power.lock, flags);
        if (pm_runtime_suspended(dev)) {
                ret = -EAGAIN;
                goto out;
        }
        pdata = acpi_driver_data(adev);
        if (WARN_ON(!pdata || !pdata->mmio_base)) {
                ret = -ENODEV;
                goto out;
        }
        *val = __lpss_reg_read(pdata, reg);

 out:
        spin_unlock_irqrestore(&dev->power.lock, flags);
        return ret;
}

static ssize_t lpss_ltr_show(struct device *dev, struct device_attribute *attr,
                             char *buf)
{
        u32 ltr_value = 0;
        unsigned int reg;
        int ret;

        reg = strcmp(attr->attr.name, "auto_ltr") ? LPSS_SW_LTR : LPSS_AUTO_LTR;
        ret = lpss_reg_read(dev, reg, &ltr_value);
        if (ret)
                return ret;

        return snprintf(buf, PAGE_SIZE, "%08x\n", ltr_value);
}

static ssize_t lpss_ltr_mode_show(struct device *dev,
                                  struct device_attribute *attr, char *buf)
{
        u32 ltr_mode = 0;
        char *outstr;
        int ret;

        ret = lpss_reg_read(dev, LPSS_GENERAL, &ltr_mode);
        if (ret)
                return ret;

        outstr = (ltr_mode & LPSS_GENERAL_LTR_MODE_SW) ? "sw" : "auto";
        return sprintf(buf, "%s\n", outstr);
}

static DEVICE_ATTR(auto_ltr, S_IRUSR, lpss_ltr_show, NULL);
static DEVICE_ATTR(sw_ltr, S_IRUSR, lpss_ltr_show, NULL);
static DEVICE_ATTR(ltr_mode, S_IRUSR, lpss_ltr_mode_show, NULL);

static struct attribute *lpss_attrs[] = {
        &dev_attr_auto_ltr.attr,
        &dev_attr_sw_ltr.attr,
        &dev_attr_ltr_mode.attr,
        NULL,
};

static const struct attribute_group lpss_attr_group = {
        .attrs = lpss_attrs,
        .name = "lpss_ltr",
};

static void acpi_lpss_set_ltr(struct device *dev, s32 val)
{
        struct lpss_private_data *pdata = acpi_driver_data(ACPI_COMPANION(dev));
        u32 ltr_mode, ltr_val;

        ltr_mode = __lpss_reg_read(pdata, LPSS_GENERAL);
        if (val < 0) {
                if (ltr_mode & LPSS_GENERAL_LTR_MODE_SW) {
                        ltr_mode &= ~LPSS_GENERAL_LTR_MODE_SW;
                        __lpss_reg_write(ltr_mode, pdata, LPSS_GENERAL);
                }
                return;
        }
        ltr_val = __lpss_reg_read(pdata, LPSS_SW_LTR) & ~LPSS_LTR_SNOOP_MASK;
        if (val >= LPSS_LTR_SNOOP_LAT_CUTOFF) {
                ltr_val |= LPSS_LTR_SNOOP_LAT_32US;
                val = LPSS_LTR_MAX_VAL;
        } else if (val > LPSS_LTR_MAX_VAL) {
                ltr_val |= LPSS_LTR_SNOOP_LAT_32US | LPSS_LTR_SNOOP_REQ;
                val >>= LPSS_LTR_SNOOP_LAT_SHIFT;
        } else {
                ltr_val |= LPSS_LTR_SNOOP_LAT_1US | LPSS_LTR_SNOOP_REQ;
        }
        ltr_val |= val;
        __lpss_reg_write(ltr_val, pdata, LPSS_SW_LTR);
        if (!(ltr_mode & LPSS_GENERAL_LTR_MODE_SW)) {
                ltr_mode |= LPSS_GENERAL_LTR_MODE_SW;
                __lpss_reg_write(ltr_mode, pdata, LPSS_GENERAL);
        }
}

#ifdef CONFIG_PM
/**
 * acpi_lpss_save_ctx() - Save the private registers of LPSS device
 * @dev: LPSS device
 * @pdata: pointer to the private data of the LPSS device
 *
 * Most LPSS devices have private registers which may loose their context when
 * the device is powered down. acpi_lpss_save_ctx() saves those registers into
 * prv_reg_ctx array.
 */
static void acpi_lpss_save_ctx(struct device *dev,
                               struct lpss_private_data *pdata)
{
        unsigned int i;

        for (i = 0; i < LPSS_PRV_REG_COUNT; i++) {
                unsigned long offset = i * sizeof(u32);

                pdata->prv_reg_ctx[i] = __lpss_reg_read(pdata, offset);
                dev_dbg(dev, "saving 0x%08x from LPSS reg at offset 0x%02lx\n",
                        pdata->prv_reg_ctx[i], offset);
        }
}

/**
 * acpi_lpss_restore_ctx() - Restore the private registers of LPSS device
 * @dev: LPSS device
 * @pdata: pointer to the private data of the LPSS device
 *
 * Restores the registers that were previously stored with acpi_lpss_save_ctx().
 */
static void acpi_lpss_restore_ctx(struct device *dev,
                                  struct lpss_private_data *pdata)
{
        unsigned int i;

        for (i = 0; i < LPSS_PRV_REG_COUNT; i++) {
                unsigned long offset = i * sizeof(u32);

                __lpss_reg_write(pdata->prv_reg_ctx[i], pdata, offset);
                dev_dbg(dev, "restoring 0x%08x to LPSS reg at offset 0x%02lx\n",
                        pdata->prv_reg_ctx[i], offset);
        }
}

static void acpi_lpss_d3_to_d0_delay(struct lpss_private_data *pdata)
{
        /*
         * The following delay is needed or the subsequent write operations may
         * fail. The LPSS devices are actually PCI devices and the PCI spec
         * expects 10ms delay before the device can be accessed after D3 to D0
         * transition. However some platforms like BSW does not need this delay.
         */
        unsigned int delay = 10;        /* default 10ms delay */

        if (pdata->dev_desc->flags & LPSS_NO_D3_DELAY)
                delay = 0;

        msleep(delay);
}

static int acpi_lpss_activate(struct device *dev)
{
        struct lpss_private_data *pdata = acpi_driver_data(ACPI_COMPANION(dev));
        int ret;

        ret = acpi_dev_resume(dev);
        if (ret)
                return ret;

        acpi_lpss_d3_to_d0_delay(pdata);

        /*
         * This is called only on ->probe() stage where a device is either in
         * known state defined by BIOS or most likely powered off. Due to this
         * we have to deassert reset line to be sure that ->probe() will
         * recognize the device.
         */
        if (pdata->dev_desc->flags & LPSS_SAVE_CTX)
                lpss_deassert_reset(pdata);

        return 0;
}

static void acpi_lpss_dismiss(struct device *dev)
{
        acpi_dev_suspend(dev, false);
}

/* IOSF SB for LPSS island */
#define LPSS_IOSF_UNIT_LPIOEP           0xA0
#define LPSS_IOSF_UNIT_LPIO1            0xAB
#define LPSS_IOSF_UNIT_LPIO2            0xAC

#define LPSS_IOSF_PMCSR                 0x84
#define LPSS_PMCSR_D0                   0
#define LPSS_PMCSR_D3hot                3
#define LPSS_PMCSR_Dx_MASK              GENMASK(1, 0)

#define LPSS_IOSF_GPIODEF0              0x154
#define LPSS_GPIODEF0_DMA1_D3           BIT(2)
#define LPSS_GPIODEF0_DMA2_D3           BIT(3)
#define LPSS_GPIODEF0_DMA_D3_MASK       GENMASK(3, 2)
#define LPSS_GPIODEF0_DMA_LLP           BIT(13)

static DEFINE_MUTEX(lpss_iosf_mutex);
static bool lpss_iosf_d3_entered = true;

static void lpss_iosf_enter_d3_state(void)
{
        u32 value1 = 0;
        u32 mask1 = LPSS_GPIODEF0_DMA_D3_MASK | LPSS_GPIODEF0_DMA_LLP;
        u32 value2 = LPSS_PMCSR_D3hot;
        u32 mask2 = LPSS_PMCSR_Dx_MASK;
        /*
         * PMC provides an information about actual status of the LPSS devices.
         * Here we read the values related to LPSS power island, i.e. LPSS
         * devices, excluding both LPSS DMA controllers, along with SCC domain.
         */
        u32 func_dis, d3_sts_0, pmc_status;
        int ret;

        ret = pmc_atom_read(PMC_FUNC_DIS, &func_dis);
        if (ret)
                return;

        mutex_lock(&lpss_iosf_mutex);

        ret = pmc_atom_read(PMC_D3_STS_0, &d3_sts_0);
        if (ret)
                goto exit;

        /*
         * Get the status of entire LPSS power island per device basis.
         * Shutdown both LPSS DMA controllers if and only if all other devices
         * are already in D3hot.
         */
        pmc_status = (~(d3_sts_0 | func_dis)) & pmc_atom_d3_mask;
        if (pmc_status)
                goto exit;

        iosf_mbi_modify(LPSS_IOSF_UNIT_LPIO1, MBI_CFG_WRITE,
                        LPSS_IOSF_PMCSR, value2, mask2);

        iosf_mbi_modify(LPSS_IOSF_UNIT_LPIO2, MBI_CFG_WRITE,
                        LPSS_IOSF_PMCSR, value2, mask2);

        iosf_mbi_modify(LPSS_IOSF_UNIT_LPIOEP, MBI_CR_WRITE,
                        LPSS_IOSF_GPIODEF0, value1, mask1);

        lpss_iosf_d3_entered = true;

exit:
        mutex_unlock(&lpss_iosf_mutex);
}

static void lpss_iosf_exit_d3_state(void)
{
        u32 value1 = LPSS_GPIODEF0_DMA1_D3 | LPSS_GPIODEF0_DMA2_D3 |
                     LPSS_GPIODEF0_DMA_LLP;
        u32 mask1 = LPSS_GPIODEF0_DMA_D3_MASK | LPSS_GPIODEF0_DMA_LLP;
        u32 value2 = LPSS_PMCSR_D0;
        u32 mask2 = LPSS_PMCSR_Dx_MASK;

        mutex_lock(&lpss_iosf_mutex);

        if (!lpss_iosf_d3_entered)
                goto exit;

        lpss_iosf_d3_entered = false;

        iosf_mbi_modify(LPSS_IOSF_UNIT_LPIOEP, MBI_CR_WRITE,
                        LPSS_IOSF_GPIODEF0, value1, mask1);

        iosf_mbi_modify(LPSS_IOSF_UNIT_LPIO2, MBI_CFG_WRITE,
                        LPSS_IOSF_PMCSR, value2, mask2);

        iosf_mbi_modify(LPSS_IOSF_UNIT_LPIO1, MBI_CFG_WRITE,
                        LPSS_IOSF_PMCSR, value2, mask2);

exit:
        mutex_unlock(&lpss_iosf_mutex);
}

static int acpi_lpss_suspend(struct device *dev, bool wakeup)
{
        struct lpss_private_data *pdata = acpi_driver_data(ACPI_COMPANION(dev));
        int ret;

        if (pdata->dev_desc->flags & LPSS_SAVE_CTX)
                acpi_lpss_save_ctx(dev, pdata);

        ret = acpi_dev_suspend(dev, wakeup);

        /*
         * This call must be last in the sequence, otherwise PMC will return
         * wrong status for devices being about to be powered off. See
         * lpss_iosf_enter_d3_state() for further information.
         */
        if (acpi_target_system_state() == ACPI_STATE_S0 &&
            lpss_quirks & LPSS_QUIRK_ALWAYS_POWER_ON && iosf_mbi_available())
                lpss_iosf_enter_d3_state();

        return ret;
}

static int acpi_lpss_resume(struct device *dev)
{
        struct lpss_private_data *pdata = acpi_driver_data(ACPI_COMPANION(dev));
        int ret;

        /*
         * This call is kept first to be in symmetry with
         * acpi_lpss_runtime_suspend() one.
         */
        if (lpss_quirks & LPSS_QUIRK_ALWAYS_POWER_ON && iosf_mbi_available())
                lpss_iosf_exit_d3_state();

        ret = acpi_dev_resume(dev);
        if (ret)
                return ret;

        acpi_lpss_d3_to_d0_delay(pdata);

        if (pdata->dev_desc->flags & LPSS_SAVE_CTX)
                acpi_lpss_restore_ctx(dev, pdata);

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int acpi_lpss_do_suspend_late(struct device *dev)
{
        int ret;

        if (dev_pm_smart_suspend_and_suspended(dev))
                return 0;

        ret = pm_generic_suspend_late(dev);
        return ret ? ret : acpi_lpss_suspend(dev, device_may_wakeup(dev));
}

static int acpi_lpss_suspend_late(struct device *dev)
{
        struct lpss_private_data *pdata = acpi_driver_data(ACPI_COMPANION(dev));

        if (pdata->dev_desc->resume_from_noirq)
                return 0;

        return acpi_lpss_do_suspend_late(dev);
}

static int acpi_lpss_suspend_noirq(struct device *dev)
{
        struct lpss_private_data *pdata = acpi_driver_data(ACPI_COMPANION(dev));
        int ret;

        if (pdata->dev_desc->resume_from_noirq) {
                /*
                 * The driver's ->suspend_late callback will be invoked by
                 * acpi_lpss_do_suspend_late(), with the assumption that the
                 * driver really wanted to run that code in ->suspend_noirq, but
                 * it could not run after acpi_dev_suspend() and the driver
                 * expected the latter to be called in the "late" phase.
                 */
                ret = acpi_lpss_do_suspend_late(dev);
                if (ret)
                        return ret;
        }

        return acpi_subsys_suspend_noirq(dev);
}

static int acpi_lpss_do_resume_early(struct device *dev)
{
        int ret = acpi_lpss_resume(dev);

        return ret ? ret : pm_generic_resume_early(dev);
}

static int acpi_lpss_resume_early(struct device *dev)
{
        struct lpss_private_data *pdata = acpi_driver_data(ACPI_COMPANION(dev));

        if (pdata->dev_desc->resume_from_noirq)
                return 0;

        return acpi_lpss_do_resume_early(dev);
}

static int acpi_lpss_resume_noirq(struct device *dev)
{
        struct lpss_private_data *pdata = acpi_driver_data(ACPI_COMPANION(dev));
        int ret;

        /* Follow acpi_subsys_resume_noirq(). */
        if (dev_pm_may_skip_resume(dev))
                return 0;

        if (dev_pm_smart_suspend_and_suspended(dev))
                pm_runtime_set_active(dev);

        ret = pm_generic_resume_noirq(dev);
        if (ret)
                return ret;

        if (!pdata->dev_desc->resume_from_noirq)
                return 0;

        /*
         * The driver's ->resume_early callback will be invoked by
         * acpi_lpss_do_resume_early(), with the assumption that the driver
         * really wanted to run that code in ->resume_noirq, but it could not
         * run before acpi_dev_resume() and the driver expected the latter to be
         * called in the "early" phase.
         */
        return acpi_lpss_do_resume_early(dev);
}

static int acpi_lpss_do_restore_early(struct device *dev)
{
        int ret = acpi_lpss_resume(dev);

        return ret ? ret : pm_generic_restore_early(dev);
}

static int acpi_lpss_restore_early(struct device *dev)
{
        struct lpss_private_data *pdata = acpi_driver_data(ACPI_COMPANION(dev));

        if (pdata->dev_desc->resume_from_noirq)
                return 0;

        return acpi_lpss_do_restore_early(dev);
}

static int acpi_lpss_restore_noirq(struct device *dev)
{
        struct lpss_private_data *pdata = acpi_driver_data(ACPI_COMPANION(dev));
        int ret;

        ret = pm_generic_restore_noirq(dev);
        if (ret)
                return ret;

        if (!pdata->dev_desc->resume_from_noirq)
                return 0;

        /* This is analogous to what happens in acpi_lpss_resume_noirq(). */
        return acpi_lpss_do_restore_early(dev);
}

static int acpi_lpss_do_poweroff_late(struct device *dev)
{
        int ret = pm_generic_poweroff_late(dev);

        return ret ? ret : acpi_lpss_suspend(dev, device_may_wakeup(dev));
}

static int acpi_lpss_poweroff_late(struct device *dev)
{
        struct lpss_private_data *pdata = acpi_driver_data(ACPI_COMPANION(dev));

        if (dev_pm_smart_suspend_and_suspended(dev))
                return 0;

        if (pdata->dev_desc->resume_from_noirq)
                return 0;

        return acpi_lpss_do_poweroff_late(dev);
}

static int acpi_lpss_poweroff_noirq(struct device *dev)
{
        struct lpss_private_data *pdata = acpi_driver_data(ACPI_COMPANION(dev));

        if (dev_pm_smart_suspend_and_suspended(dev))
                return 0;

        if (pdata->dev_desc->resume_from_noirq) {
                /* This is analogous to the acpi_lpss_suspend_noirq() case. */
                int ret = acpi_lpss_do_poweroff_late(dev);
                if (ret)
                        return ret;
        }

        return pm_generic_poweroff_noirq(dev);
}
#endif /* CONFIG_PM_SLEEP */

static int acpi_lpss_runtime_suspend(struct device *dev)
{
        int ret = pm_generic_runtime_suspend(dev);

        return ret ? ret : acpi_lpss_suspend(dev, true);
}

static int acpi_lpss_runtime_resume(struct device *dev)
{
        int ret = acpi_lpss_resume(dev);

        return ret ? ret : pm_generic_runtime_resume(dev);
}
#endif /* CONFIG_PM */

static struct dev_pm_domain acpi_lpss_pm_domain = {
#ifdef CONFIG_PM
        .activate = acpi_lpss_activate,
        .dismiss = acpi_lpss_dismiss,
#endif
        .ops = {
#ifdef CONFIG_PM
#ifdef CONFIG_PM_SLEEP
                .prepare = acpi_subsys_prepare,
                .complete = acpi_subsys_complete,
                .suspend = acpi_subsys_suspend,
                .suspend_late = acpi_lpss_suspend_late,
                .suspend_noirq = acpi_lpss_suspend_noirq,
                .resume_noirq = acpi_lpss_resume_noirq,
                .resume_early = acpi_lpss_resume_early,
                .freeze = acpi_subsys_freeze,
                .poweroff = acpi_subsys_poweroff,
                .poweroff_late = acpi_lpss_poweroff_late,
                .poweroff_noirq = acpi_lpss_poweroff_noirq,
                .restore_noirq = acpi_lpss_restore_noirq,
                .restore_early = acpi_lpss_restore_early,
#endif
                .runtime_suspend = acpi_lpss_runtime_suspend,
                .runtime_resume = acpi_lpss_runtime_resume,
#endif
        },
};

static int acpi_lpss_platform_notify(struct notifier_block *nb,
                                     unsigned long action, void *data)
{
        struct platform_device *pdev = to_platform_device(data);
        struct lpss_private_data *pdata;
        struct acpi_device *adev;
        const struct acpi_device_id *id;

        id = acpi_match_device(acpi_lpss_device_ids, &pdev->dev);
        if (!id || !id->driver_data)
                return 0;

        if (acpi_bus_get_device(ACPI_HANDLE(&pdev->dev), &adev))
                return 0;

        pdata = acpi_driver_data(adev);
        if (!pdata)
                return 0;

        if (pdata->mmio_base &&
            pdata->mmio_size < pdata->dev_desc->prv_offset + LPSS_LTR_SIZE) {
                dev_err(&pdev->dev, "MMIO size insufficient to access LTR\n");
                return 0;
        }

        switch (action) {
        case BUS_NOTIFY_BIND_DRIVER:
                dev_pm_domain_set(&pdev->dev, &acpi_lpss_pm_domain);
                break;
        case BUS_NOTIFY_DRIVER_NOT_BOUND:
        case BUS_NOTIFY_UNBOUND_DRIVER:
                dev_pm_domain_set(&pdev->dev, NULL);
                break;
        case BUS_NOTIFY_ADD_DEVICE:
                dev_pm_domain_set(&pdev->dev, &acpi_lpss_pm_domain);
                if (pdata->dev_desc->flags & LPSS_LTR)
                        return sysfs_create_group(&pdev->dev.kobj,
                                                  &lpss_attr_group);
                break;
        case BUS_NOTIFY_DEL_DEVICE:
                if (pdata->dev_desc->flags & LPSS_LTR)
                        sysfs_remove_group(&pdev->dev.kobj, &lpss_attr_group);
                dev_pm_domain_set(&pdev->dev, NULL);
                break;
        default:
                break;
        }

        return 0;
}

static struct notifier_block acpi_lpss_nb = {
        .notifier_call = acpi_lpss_platform_notify,
};

static void acpi_lpss_bind(struct device *dev)
{
        struct lpss_private_data *pdata = acpi_driver_data(ACPI_COMPANION(dev));

        if (!pdata || !pdata->mmio_base || !(pdata->dev_desc->flags & LPSS_LTR))
                return;

        if (pdata->mmio_size >= pdata->dev_desc->prv_offset + LPSS_LTR_SIZE)
                dev->power.set_latency_tolerance = acpi_lpss_set_ltr;
        else
                dev_err(dev, "MMIO size insufficient to access LTR\n");
}

static void acpi_lpss_unbind(struct device *dev)
{
        dev->power.set_latency_tolerance = NULL;
}

static struct acpi_scan_handler lpss_handler = {
        .ids = acpi_lpss_device_ids,
        .attach = acpi_lpss_create_device,
        .bind = acpi_lpss_bind,
        .unbind = acpi_lpss_unbind,
};

void __init acpi_lpss_init(void)
{
        const struct x86_cpu_id *id;
        int ret;

        ret = lpt_clk_init();
        if (ret)
                return;

        id = x86_match_cpu(lpss_cpu_ids);
        if (id)
                lpss_quirks |= LPSS_QUIRK_ALWAYS_POWER_ON;

        bus_register_notifier(&platform_bus_type, &acpi_lpss_nb);
        acpi_scan_add_handler(&lpss_handler);
}

#else

static struct acpi_scan_handler lpss_handler = {
        .ids = acpi_lpss_device_ids,
};

void __init acpi_lpss_init(void)
{
        acpi_scan_add_handler(&lpss_handler);
}

#endif /* CONFIG_X86_INTEL_LPSS */