// SPDX-License-Identifier: GPL-2.0
/*
 * PCIe Enclosure management driver created for LED interfaces based on
 * indications. It says *what indications* blink but does not specify *how*
 * they blink - it is hardware defined.
 *
 * The driver name refers to Native PCIe Enclosure Management. It is
 * first indication oriented standard with specification.
 *
 * Native PCIe Enclosure Management (NPEM)
 *      PCIe Base Specification r6.1 sec 6.28, 7.9.19
 *
 * _DSM Definitions for PCIe SSD Status LED
 *       PCI Firmware Specification, r3.3 sec 4.7
 *
 * Two backends are supported to manipulate indications: Direct NPEM register
 * access (npem_ops) and indirect access through the ACPI _DSM (dsm_ops).
 * _DSM is used if supported, else NPEM.
 *
 * Copyright (c) 2021-2022 Dell Inc.
 * Copyright (c) 2023-2024 Intel Corporation
 *      Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>
 */

#include <linux/acpi.h>
#include <linux/bitops.h>
#include <linux/errno.h>
#include <linux/iopoll.h>
#include <linux/leds.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/pci_regs.h>
#include <linux/types.h>
#include <linux/uleds.h>

#include "pci.h"

struct indication {
        u32 bit;
        const char *name;
};

static const struct indication npem_indications[] = {
        {PCI_NPEM_IND_OK,       "enclosure:ok"},
        {PCI_NPEM_IND_LOCATE,   "enclosure:locate"},
        {PCI_NPEM_IND_FAIL,     "enclosure:fail"},
        {PCI_NPEM_IND_REBUILD,  "enclosure:rebuild"},
        {PCI_NPEM_IND_PFA,      "enclosure:pfa"},
        {PCI_NPEM_IND_HOTSPARE, "enclosure:hotspare"},
        {PCI_NPEM_IND_ICA,      "enclosure:ica"},
        {PCI_NPEM_IND_IFA,      "enclosure:ifa"},
        {PCI_NPEM_IND_IDT,      "enclosure:idt"},
        {PCI_NPEM_IND_DISABLED, "enclosure:disabled"},
        {PCI_NPEM_IND_SPEC_0,   "enclosure:specific_0"},
        {PCI_NPEM_IND_SPEC_1,   "enclosure:specific_1"},
        {PCI_NPEM_IND_SPEC_2,   "enclosure:specific_2"},
        {PCI_NPEM_IND_SPEC_3,   "enclosure:specific_3"},
        {PCI_NPEM_IND_SPEC_4,   "enclosure:specific_4"},
        {PCI_NPEM_IND_SPEC_5,   "enclosure:specific_5"},
        {PCI_NPEM_IND_SPEC_6,   "enclosure:specific_6"},
        {PCI_NPEM_IND_SPEC_7,   "enclosure:specific_7"},
        {0,                     NULL}
};

/* _DSM PCIe SSD LED States correspond to NPEM register values */
static const struct indication dsm_indications[] = {
        {PCI_NPEM_IND_OK,       "enclosure:ok"},
        {PCI_NPEM_IND_LOCATE,   "enclosure:locate"},
        {PCI_NPEM_IND_FAIL,     "enclosure:fail"},
        {PCI_NPEM_IND_REBUILD,  "enclosure:rebuild"},
        {PCI_NPEM_IND_PFA,      "enclosure:pfa"},
        {PCI_NPEM_IND_HOTSPARE, "enclosure:hotspare"},
        {PCI_NPEM_IND_ICA,      "enclosure:ica"},
        {PCI_NPEM_IND_IFA,      "enclosure:ifa"},
        {PCI_NPEM_IND_IDT,      "enclosure:idt"},
        {PCI_NPEM_IND_DISABLED, "enclosure:disabled"},
        {0,                     NULL}
};

#define for_each_indication(ind, inds) \
        for (ind = inds; ind->bit; ind++)

/*
 * The driver has internal list of supported indications. Ideally, the driver
 * should not touch bits that are not defined and for which LED devices are
 * not exposed but in reality, it needs to turn them off.
 *
 * Otherwise, there will be no possibility to turn off indications turned on by
 * other utilities or turned on by default and it leads to bad user experience.
 *
 * Additionally, it excludes NPEM commands like RESET or ENABLE.
 */
static u32 reg_to_indications(u32 caps, const struct indication *inds)
{
        const struct indication *ind;
        u32 supported_indications = 0;

        for_each_indication(ind, inds)
                supported_indications |= ind->bit;

        return caps & supported_indications;
}

/**
 * struct npem_led - LED details
 * @indication: indication details
 * @npem: NPEM device
 * @name: LED name
 * @led: LED device
 */
struct npem_led {
        const struct indication *indication;
        struct npem *npem;
        char name[LED_MAX_NAME_SIZE];
        struct led_classdev led;
};

/**
 * struct npem_ops - backend specific callbacks
 * @get_active_indications: get active indications
 *      npem: NPEM device
 *      inds: response buffer
 * @set_active_indications: set new indications
 *      npem: npem device
 *      inds: bit mask to set
 * @inds: supported indications array, set of indications is backend specific
 * @name: backend name
 */
struct npem_ops {
        int (*get_active_indications)(struct npem *npem, u32 *inds);
        int (*set_active_indications)(struct npem *npem, u32 inds);
        const struct indication *inds;
        const char *name;
};

/**
 * struct npem - NPEM device properties
 * @dev: PCI device this driver is attached to
 * @ops: backend specific callbacks
 * @lock: serializes concurrent access to NPEM device by multiple LED devices
 * @pos: cached offset of NPEM Capability Register in Configuration Space;
 *      only used if NPEM registers are accessed directly and not through _DSM
 * @supported_indications: cached bit mask of supported indications;
 *      non-indication and reserved bits in the NPEM Capability Register are
 *      cleared in this bit mask
 * @active_indications: cached bit mask of active indications;
 *      non-indication and reserved bits in the NPEM Control Register are
 *      cleared in this bit mask
 * @active_inds_initialized: whether @active_indications has been initialized;
 *      On Dell platforms, it is required that IPMI drivers are loaded before
 *      the GET_STATE_DSM method is invoked: They use an IPMI OpRegion to
 *      get/set the active LEDs. By initializing @active_indications lazily
 *      (on first access to an LED), IPMI drivers are given a chance to load.
 *      If they are not loaded in time, users will see various errors on LED
 *      access in dmesg. Once they are loaded, the errors go away and LED
 *      access becomes possible.
 * @led_cnt: size of @leds array
 * @leds: array containing LED class devices of all supported LEDs
 */
struct npem {
        struct pci_dev *dev;
        const struct npem_ops *ops;
        struct mutex lock;
        u16 pos;
        u32 supported_indications;
        u32 active_indications;
        unsigned int active_inds_initialized:1;
        int led_cnt;
        struct npem_led leds[];
};

static int npem_read_reg(struct npem *npem, u16 reg, u32 *val)
{
        int ret = pci_read_config_dword(npem->dev, npem->pos + reg, val);

        return pcibios_err_to_errno(ret);
}

static int npem_write_ctrl(struct npem *npem, u32 reg)
{
        int pos = npem->pos + PCI_NPEM_CTRL;
        int ret = pci_write_config_dword(npem->dev, pos, reg);

        return pcibios_err_to_errno(ret);
}

static int npem_get_active_indications(struct npem *npem, u32 *inds)
{
        u32 ctrl;
        int ret;

        ret = npem_read_reg(npem, PCI_NPEM_CTRL, &ctrl);
        if (ret)
                return ret;

        /* If PCI_NPEM_CTRL_ENABLE is not set then no indication should blink */
        if (!(ctrl & PCI_NPEM_CTRL_ENABLE)) {
                *inds = 0;
                return 0;
        }

        *inds = ctrl & npem->supported_indications;

        return 0;
}

static int npem_set_active_indications(struct npem *npem, u32 inds)
{
        int ctrl, ret, ret_val;
        u32 cc_status;

        lockdep_assert_held(&npem->lock);

        /* This bit is always required */
        ctrl = inds | PCI_NPEM_CTRL_ENABLE;

        ret = npem_write_ctrl(npem, ctrl);
        if (ret)
                return ret;

        /*
         * For the case where a NPEM command has not completed immediately,
         * it is recommended that software not continuously "spin" on polling
         * the status register, but rather poll under interrupt at a reduced
         * rate; for example at 10 ms intervals.
         *
         * PCIe r6.1 sec 6.28 "Implementation Note: Software Polling of NPEM
         * Command Completed"
         */
        ret = read_poll_timeout(npem_read_reg, ret_val,
                                ret_val || (cc_status & PCI_NPEM_STATUS_CC),
                                10 * USEC_PER_MSEC, USEC_PER_SEC, false, npem,
                                PCI_NPEM_STATUS, &cc_status);
        if (ret)
                return ret;
        if (ret_val)
                return ret_val;

        /*
         * All writes to control register, including writes that do not change
         * the register value, are NPEM commands and should eventually result
         * in a command completion indication in the NPEM Status Register.
         *
         * PCIe Base Specification r6.1 sec 7.9.19.3
         *
         * Register may not be updated, or other conflicting bits may be
         * cleared. Spec is not strict here. Read NPEM Control register after
         * write to keep cache in-sync.
         */
        return npem_get_active_indications(npem, &npem->active_indications);
}

static const struct npem_ops npem_ops = {
        .get_active_indications = npem_get_active_indications,
        .set_active_indications = npem_set_active_indications,
        .name = "Native PCIe Enclosure Management",
        .inds = npem_indications,
};

#define DSM_GUID GUID_INIT(0x5d524d9d, 0xfff9, 0x4d4b, 0x8c, 0xb7, 0x74, 0x7e,\
                           0xd5, 0x1e, 0x19, 0x4d)
#define GET_SUPPORTED_STATES_DSM        1
#define GET_STATE_DSM                   2
#define SET_STATE_DSM                   3

static const guid_t dsm_guid = DSM_GUID;

static bool npem_has_dsm(struct pci_dev *pdev)
{
        acpi_handle handle;

        handle = ACPI_HANDLE(&pdev->dev);
        if (!handle)
                return false;

        return acpi_check_dsm(handle, &dsm_guid, 0x1,
                              BIT(GET_SUPPORTED_STATES_DSM) |
                              BIT(GET_STATE_DSM) | BIT(SET_STATE_DSM));
}

struct dsm_output {
        u16 status;
        u8 function_specific_err;
        u8 vendor_specific_err;
        u32 state;
};

/**
 * dsm_evaluate() - send DSM PCIe SSD Status LED command
 * @pdev: PCI device
 * @dsm_func: DSM LED Function
 * @output: buffer to copy DSM Response
 * @value_to_set: value for SET_STATE_DSM function
 *
 * To not bother caller with ACPI context, the returned _DSM Output Buffer is
 * copied.
 */
static int dsm_evaluate(struct pci_dev *pdev, u64 dsm_func,
                        struct dsm_output *output, u32 value_to_set)
{
        acpi_handle handle = ACPI_HANDLE(&pdev->dev);
        union acpi_object *out_obj, arg3[2];
        union acpi_object *arg3_p = NULL;

        if (dsm_func == SET_STATE_DSM) {
                arg3[0].type = ACPI_TYPE_PACKAGE;
                arg3[0].package.count = 1;
                arg3[0].package.elements = &arg3[1];

                arg3[1].type = ACPI_TYPE_BUFFER;
                arg3[1].buffer.length = 4;
                arg3[1].buffer.pointer = (u8 *)&value_to_set;

                arg3_p = arg3;
        }

        out_obj = acpi_evaluate_dsm_typed(handle, &dsm_guid, 0x1, dsm_func,
                                          arg3_p, ACPI_TYPE_BUFFER);
        if (!out_obj)
                return -EIO;

        if (out_obj->buffer.length < sizeof(struct dsm_output)) {
                ACPI_FREE(out_obj);
                return -EIO;
        }

        memcpy(output, out_obj->buffer.pointer, sizeof(struct dsm_output));

        ACPI_FREE(out_obj);
        return 0;
}

static int dsm_get(struct pci_dev *pdev, u64 dsm_func, u32 *buf)
{
        struct dsm_output output;
        int ret = dsm_evaluate(pdev, dsm_func, &output, 0);

        if (ret)
                return ret;

        if (output.status != 0)
                return -EIO;

        *buf = output.state;
        return 0;
}

static int dsm_get_active_indications(struct npem *npem, u32 *buf)
{
        int ret = dsm_get(npem->dev, GET_STATE_DSM, buf);

        /* Filter out not supported indications in response */
        *buf &= npem->supported_indications;
        return ret;
}

static int dsm_set_active_indications(struct npem *npem, u32 value)
{
        struct dsm_output output;
        int ret = dsm_evaluate(npem->dev, SET_STATE_DSM, &output, value);

        if (ret)
                return ret;

        switch (output.status) {
        case 4:
                /*
                 * Not all bits are set. If this bit is set, the platform
                 * disregarded some or all of the request state changes. OSPM
                 * should check the resulting PCIe SSD Status LED States to see
                 * what, if anything, has changed.
                 *
                 * PCI Firmware Specification, r3.3 Table 4-19.
                 */
                if (output.function_specific_err != 1)
                        return -EIO;
                fallthrough;
        case 0:
                break;
        default:
                return -EIO;
        }

        npem->active_indications = output.state;

        return 0;
}

static const struct npem_ops dsm_ops = {
        .get_active_indications = dsm_get_active_indications,
        .set_active_indications = dsm_set_active_indications,
        .name = "_DSM PCIe SSD Status LED Management",
        .inds = dsm_indications,
};

static int npem_initialize_active_indications(struct npem *npem)
{
        int ret;

        lockdep_assert_held(&npem->lock);

        if (npem->active_inds_initialized)
                return 0;

        ret = npem->ops->get_active_indications(npem,
                                                &npem->active_indications);
        if (ret)
                return ret;

        npem->active_inds_initialized = true;
        return 0;
}

/*
 * The status of each indicator is cached on first brightness_ get/set time
 * and updated at write time.  brightness_get() is only responsible for
 * reflecting the last written/cached value.
 */
static enum led_brightness brightness_get(struct led_classdev *led)
{
        struct npem_led *nled = container_of(led, struct npem_led, led);
        struct npem *npem = nled->npem;
        int ret, val = 0;

        ret = mutex_lock_interruptible(&npem->lock);
        if (ret)
                return ret;

        ret = npem_initialize_active_indications(npem);
        if (ret)
                goto out;

        if (npem->active_indications & nled->indication->bit)
                val = 1;

out:
        mutex_unlock(&npem->lock);
        return val;
}

static int brightness_set(struct led_classdev *led,
                          enum led_brightness brightness)
{
        struct npem_led *nled = container_of(led, struct npem_led, led);
        struct npem *npem = nled->npem;
        u32 indications;
        int ret;

        ret = mutex_lock_interruptible(&npem->lock);
        if (ret)
                return ret;

        ret = npem_initialize_active_indications(npem);
        if (ret)
                goto out;

        if (brightness == 0)
                indications = npem->active_indications & ~(nled->indication->bit);
        else
                indications = npem->active_indications | nled->indication->bit;

        ret = npem->ops->set_active_indications(npem, indications);

out:
        mutex_unlock(&npem->lock);
        return ret;
}

static void npem_free(struct npem *npem)
{
        struct npem_led *nled;
        int cnt;

        if (!npem)
                return;

        for (cnt = 0; cnt < npem->led_cnt; cnt++) {
                nled = &npem->leds[cnt];

                if (nled->name[0])
                        led_classdev_unregister(&nled->led);
        }

        mutex_destroy(&npem->lock);
        kfree(npem);
}

static int pci_npem_set_led_classdev(struct npem *npem, struct npem_led *nled)
{
        struct led_classdev *led = &nled->led;
        struct led_init_data init_data = {};
        char *name = nled->name;
        int ret;

        init_data.devicename = pci_name(npem->dev);
        init_data.default_label = nled->indication->name;

        ret = led_compose_name(&npem->dev->dev, &init_data, name);
        if (ret)
                return ret;

        led->name = name;
        led->brightness_set_blocking = brightness_set;
        led->brightness_get = brightness_get;
        led->max_brightness = 1;
        led->default_trigger = "none";
        led->flags = 0;

        ret = led_classdev_register(&npem->dev->dev, led);
        if (ret)
                /* Clear the name to indicate that it is not registered. */
                name[0] = 0;
        return ret;
}

static int pci_npem_init(struct pci_dev *dev, const struct npem_ops *ops,
                         int pos, u32 caps)
{
        u32 supported = reg_to_indications(caps, ops->inds);
        int supported_cnt = hweight32(supported);
        const struct indication *indication;
        struct npem_led *nled;
        struct npem *npem;
        int led_idx = 0;
        int ret;

        npem = kzalloc_flex(*npem, leds, supported_cnt);
        if (!npem)
                return -ENOMEM;

        npem->supported_indications = supported;
        npem->led_cnt = supported_cnt;
        npem->pos = pos;
        npem->dev = dev;
        npem->ops = ops;

        mutex_init(&npem->lock);

        for_each_indication(indication, npem_indications) {
                if (!(npem->supported_indications & indication->bit))
                        continue;

                nled = &npem->leds[led_idx++];
                nled->indication = indication;
                nled->npem = npem;

                ret = pci_npem_set_led_classdev(npem, nled);
                if (ret) {
                        npem_free(npem);
                        return ret;
                }
        }

        dev->npem = npem;
        return 0;
}

void pci_npem_remove(struct pci_dev *dev)
{
        npem_free(dev->npem);
}

void pci_npem_create(struct pci_dev *dev)
{
        const struct npem_ops *ops = &npem_ops;
        int pos = 0, ret;
        u32 cap;

        if (npem_has_dsm(dev)) {
                /*
                 * OS should use the DSM for LED control if it is available
                 * PCI Firmware Spec r3.3 sec 4.7.
                 */
                ret = dsm_get(dev, GET_SUPPORTED_STATES_DSM, &cap);
                if (ret)
                        return;

                ops = &dsm_ops;
        } else {
                pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_NPEM);
                if (pos == 0)
                        return;

                if (pci_read_config_dword(dev, pos + PCI_NPEM_CAP, &cap) != 0 ||
                    (cap & PCI_NPEM_CAP_CAPABLE) == 0)
                        return;
        }

        pci_info(dev, "Configuring %s\n", ops->name);

        ret = pci_npem_init(dev, ops, pos, cap);
        if (ret)
                pci_err(dev, "Failed to register %s, err: %d\n", ops->name,
                        ret);
}