// SPDX-License-Identifier: GPL-2.0
/*
 * PCI Express Precision Time Measurement
 * Copyright (c) 2016, Intel Corporation.
 */

#include <linux/bitfield.h>
#include <linux/debugfs.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/pci.h>
#include "../pci.h"

/*
 * If the next upstream device supports PTM, return it; otherwise return
 * NULL.  PTM Messages are local, so both link partners must support it.
 */
static struct pci_dev *pci_upstream_ptm(struct pci_dev *dev)
{
        struct pci_dev *ups = pci_upstream_bridge(dev);

        /*
         * Switch Downstream Ports are not permitted to have a PTM
         * capability; their PTM behavior is controlled by the Upstream
         * Port (PCIe r5.0, sec 7.9.16), so if the upstream bridge is a
         * Switch Downstream Port, look up one more level.
         */
        if (ups && pci_pcie_type(ups) == PCI_EXP_TYPE_DOWNSTREAM)
                ups = pci_upstream_bridge(ups);

        if (ups && ups->ptm_cap)
                return ups;

        return NULL;
}

/*
 * Find the PTM Capability (if present) and extract the information we need
 * to use it.
 */
void pci_ptm_init(struct pci_dev *dev)
{
        u16 ptm;
        u32 cap;
        struct pci_dev *ups;

        if (!pci_is_pcie(dev))
                return;

        ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM);
        if (!ptm)
                return;

        dev->ptm_cap = ptm;
        pci_add_ext_cap_save_buffer(dev, PCI_EXT_CAP_ID_PTM, sizeof(u32));

        pci_read_config_dword(dev, ptm + PCI_PTM_CAP, &cap);
        dev->ptm_granularity = FIELD_GET(PCI_PTM_GRANULARITY_MASK, cap);

        /*
         * Per the spec recommendation (PCIe r6.0, sec 7.9.15.3), select the
         * furthest upstream Time Source as the PTM Root.  For Endpoints,
         * "the Effective Granularity is the maximum Local Clock Granularity
         * reported by the PTM Root and all intervening PTM Time Sources."
         */
        ups = pci_upstream_ptm(dev);
        if (ups) {
                if (ups->ptm_granularity == 0)
                        dev->ptm_granularity = 0;
                else if (ups->ptm_granularity > dev->ptm_granularity)
                        dev->ptm_granularity = ups->ptm_granularity;
        } else if (cap & PCI_PTM_CAP_ROOT) {
                dev->ptm_root = 1;
        } else if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) {

                /*
                 * Per sec 7.9.15.3, this should be the Local Clock
                 * Granularity of the associated Time Source.  But it
                 * doesn't say how to find that Time Source.
                 */
                dev->ptm_granularity = 0;
        }

        if (cap & PCI_PTM_CAP_RES)
                dev->ptm_responder = 1;
        if (cap & PCI_PTM_CAP_REQ)
                dev->ptm_requester = 1;

        if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT ||
            pci_pcie_type(dev) == PCI_EXP_TYPE_UPSTREAM)
                pci_enable_ptm(dev, NULL);
}

void pci_save_ptm_state(struct pci_dev *dev)
{
        u16 ptm = dev->ptm_cap;
        struct pci_cap_saved_state *save_state;
        u32 *cap;

        if (!ptm)
                return;

        save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_PTM);
        if (!save_state)
                return;

        cap = (u32 *)&save_state->cap.data[0];
        pci_read_config_dword(dev, ptm + PCI_PTM_CTRL, cap);
}

void pci_restore_ptm_state(struct pci_dev *dev)
{
        u16 ptm = dev->ptm_cap;
        struct pci_cap_saved_state *save_state;
        u32 *cap;

        if (!ptm)
                return;

        save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_PTM);
        if (!save_state)
                return;

        cap = (u32 *)&save_state->cap.data[0];
        pci_write_config_dword(dev, ptm + PCI_PTM_CTRL, *cap);
}

/* Enable PTM in the Control register if possible */
static int __pci_enable_ptm(struct pci_dev *dev)
{
        u16 ptm = dev->ptm_cap;
        struct pci_dev *ups;
        u32 ctrl;

        if (!ptm)
                return -EINVAL;

        /*
         * A device uses local PTM Messages to request time information
         * from a PTM Root that's farther upstream.  Every device along the
         * path must support PTM and have it enabled so it can handle the
         * messages.  Therefore, if this device is not a PTM Root, the
         * upstream link partner must have PTM enabled before we can enable
         * PTM.
         */
        if (!dev->ptm_root) {
                ups = pci_upstream_ptm(dev);
                if (!ups || !ups->ptm_enabled)
                        return -EINVAL;
        }

        switch (pci_pcie_type(dev)) {
        case PCI_EXP_TYPE_ROOT_PORT:
                if (!dev->ptm_root)
                        return -EINVAL;
                break;
        case PCI_EXP_TYPE_UPSTREAM:
                if (!dev->ptm_responder)
                        return -EINVAL;
                break;
        case PCI_EXP_TYPE_ENDPOINT:
        case PCI_EXP_TYPE_LEG_END:
                if (!dev->ptm_requester)
                        return -EINVAL;
                break;
        default:
                return -EINVAL;
        }

        pci_read_config_dword(dev, ptm + PCI_PTM_CTRL, &ctrl);

        ctrl |= PCI_PTM_CTRL_ENABLE;
        ctrl &= ~PCI_PTM_GRANULARITY_MASK;
        ctrl |= FIELD_PREP(PCI_PTM_GRANULARITY_MASK, dev->ptm_granularity);
        if (dev->ptm_root)
                ctrl |= PCI_PTM_CTRL_ROOT;

        pci_write_config_dword(dev, ptm + PCI_PTM_CTRL, ctrl);
        return 0;
}

/**
 * pci_enable_ptm() - Enable Precision Time Measurement
 * @dev: PCI device
 * @granularity: pointer to return granularity
 *
 * Enable Precision Time Measurement for @dev.  If successful and
 * @granularity is non-NULL, return the Effective Granularity.
 *
 * Return: zero if successful, or -EINVAL if @dev lacks a PTM Capability or
 * is not a PTM Root and lacks an upstream path of PTM-enabled devices.
 */
int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
{
        int rc;
        char clock_desc[8];

        rc = __pci_enable_ptm(dev);
        if (rc)
                return rc;

        dev->ptm_enabled = 1;

        if (granularity)
                *granularity = dev->ptm_granularity;

        switch (dev->ptm_granularity) {
        case 0:
                snprintf(clock_desc, sizeof(clock_desc), "unknown");
                break;
        case 255:
                snprintf(clock_desc, sizeof(clock_desc), ">254ns");
                break;
        default:
                snprintf(clock_desc, sizeof(clock_desc), "%uns",
                         dev->ptm_granularity);
                break;
        }
        pci_info(dev, "PTM enabled%s, %s granularity\n",
                 dev->ptm_root ? " (root)" : "", clock_desc);

        return 0;
}
EXPORT_SYMBOL(pci_enable_ptm);

static void __pci_disable_ptm(struct pci_dev *dev)
{
        u16 ptm = dev->ptm_cap;
        u32 ctrl;

        if (!ptm)
                return;

        pci_read_config_dword(dev, ptm + PCI_PTM_CTRL, &ctrl);
        ctrl &= ~(PCI_PTM_CTRL_ENABLE | PCI_PTM_CTRL_ROOT);
        pci_write_config_dword(dev, ptm + PCI_PTM_CTRL, ctrl);
}

/**
 * pci_disable_ptm() - Disable Precision Time Measurement
 * @dev: PCI device
 *
 * Disable Precision Time Measurement for @dev.
 */
void pci_disable_ptm(struct pci_dev *dev)
{
        if (dev->ptm_enabled) {
                __pci_disable_ptm(dev);
                dev->ptm_enabled = 0;
        }
}
EXPORT_SYMBOL(pci_disable_ptm);

/*
 * Disable PTM, but preserve dev->ptm_enabled so we silently re-enable it on
 * resume if necessary.
 */
void pci_suspend_ptm(struct pci_dev *dev)
{
        if (dev->ptm_enabled)
                __pci_disable_ptm(dev);
}

/* If PTM was enabled before suspend, re-enable it when resuming */
void pci_resume_ptm(struct pci_dev *dev)
{
        if (dev->ptm_enabled)
                __pci_enable_ptm(dev);
}

bool pcie_ptm_enabled(struct pci_dev *dev)
{
        if (!dev)
                return false;

        return dev->ptm_enabled;
}
EXPORT_SYMBOL(pcie_ptm_enabled);

#if IS_ENABLED(CONFIG_DEBUG_FS)
static ssize_t context_update_write(struct file *file, const char __user *ubuf,
                             size_t count, loff_t *ppos)
{
        struct pci_ptm_debugfs *ptm_debugfs = file->private_data;
        char buf[7];
        int ret;
        u8 mode;

        if (!ptm_debugfs->ops->context_update_write)
                return -EOPNOTSUPP;

        if (count < 1 || count >= sizeof(buf))
                return -EINVAL;

        ret = copy_from_user(buf, ubuf, count);
        if (ret)
                return -EFAULT;

        buf[count] = '\0';

        if (sysfs_streq(buf, "auto"))
                mode = PCIE_PTM_CONTEXT_UPDATE_AUTO;
        else if (sysfs_streq(buf, "manual"))
                mode = PCIE_PTM_CONTEXT_UPDATE_MANUAL;
        else
                return -EINVAL;

        mutex_lock(&ptm_debugfs->lock);
        ret = ptm_debugfs->ops->context_update_write(ptm_debugfs->pdata, mode);
        mutex_unlock(&ptm_debugfs->lock);
        if (ret)
                return ret;

        return count;
}

static ssize_t context_update_read(struct file *file, char __user *ubuf,
                             size_t count, loff_t *ppos)
{
        struct pci_ptm_debugfs *ptm_debugfs = file->private_data;
        char buf[8]; /* Extra space for NULL termination at the end */
        ssize_t pos;
        u8 mode;

        if (!ptm_debugfs->ops->context_update_read)
                return -EOPNOTSUPP;

        mutex_lock(&ptm_debugfs->lock);
        ptm_debugfs->ops->context_update_read(ptm_debugfs->pdata, &mode);
        mutex_unlock(&ptm_debugfs->lock);

        if (mode == PCIE_PTM_CONTEXT_UPDATE_AUTO)
                pos = scnprintf(buf, sizeof(buf), "auto\n");
        else
                pos = scnprintf(buf, sizeof(buf), "manual\n");

        return simple_read_from_buffer(ubuf, count, ppos, buf, pos);
}

static const struct file_operations context_update_fops = {
        .open = simple_open,
        .read = context_update_read,
        .write = context_update_write,
};

static int context_valid_get(void *data, u64 *val)
{
        struct pci_ptm_debugfs *ptm_debugfs = data;
        bool valid;
        int ret;

        if (!ptm_debugfs->ops->context_valid_read)
                return -EOPNOTSUPP;

        mutex_lock(&ptm_debugfs->lock);
        ret = ptm_debugfs->ops->context_valid_read(ptm_debugfs->pdata, &valid);
        mutex_unlock(&ptm_debugfs->lock);
        if (ret)
                return ret;

        *val = valid;

        return 0;
}

static int context_valid_set(void *data, u64 val)
{
        struct pci_ptm_debugfs *ptm_debugfs = data;
        int ret;

        if (!ptm_debugfs->ops->context_valid_write)
                return -EOPNOTSUPP;

        mutex_lock(&ptm_debugfs->lock);
        ret = ptm_debugfs->ops->context_valid_write(ptm_debugfs->pdata, !!val);
        mutex_unlock(&ptm_debugfs->lock);

        return ret;
}

DEFINE_DEBUGFS_ATTRIBUTE(context_valid_fops, context_valid_get,
                         context_valid_set, "%llu\n");

static int local_clock_get(void *data, u64 *val)
{
        struct pci_ptm_debugfs *ptm_debugfs = data;
        u64 clock;
        int ret;

        if (!ptm_debugfs->ops->local_clock_read)
                return -EOPNOTSUPP;

        ret = ptm_debugfs->ops->local_clock_read(ptm_debugfs->pdata, &clock);
        if (ret)
                return ret;

        *val = clock;

        return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(local_clock_fops, local_clock_get, NULL, "%llu\n");

static int master_clock_get(void *data, u64 *val)
{
        struct pci_ptm_debugfs *ptm_debugfs = data;
        u64 clock;
        int ret;

        if (!ptm_debugfs->ops->master_clock_read)
                return -EOPNOTSUPP;

        ret = ptm_debugfs->ops->master_clock_read(ptm_debugfs->pdata, &clock);
        if (ret)
                return ret;

        *val = clock;

        return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(master_clock_fops, master_clock_get, NULL, "%llu\n");

static int t1_get(void *data, u64 *val)
{
        struct pci_ptm_debugfs *ptm_debugfs = data;
        u64 clock;
        int ret;

        if (!ptm_debugfs->ops->t1_read)
                return -EOPNOTSUPP;

        ret = ptm_debugfs->ops->t1_read(ptm_debugfs->pdata, &clock);
        if (ret)
                return ret;

        *val = clock;

        return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(t1_fops, t1_get, NULL, "%llu\n");

static int t2_get(void *data, u64 *val)
{
        struct pci_ptm_debugfs *ptm_debugfs = data;
        u64 clock;
        int ret;

        if (!ptm_debugfs->ops->t2_read)
                return -EOPNOTSUPP;

        ret = ptm_debugfs->ops->t2_read(ptm_debugfs->pdata, &clock);
        if (ret)
                return ret;

        *val = clock;

        return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(t2_fops, t2_get, NULL, "%llu\n");

static int t3_get(void *data, u64 *val)
{
        struct pci_ptm_debugfs *ptm_debugfs = data;
        u64 clock;
        int ret;

        if (!ptm_debugfs->ops->t3_read)
                return -EOPNOTSUPP;

        ret = ptm_debugfs->ops->t3_read(ptm_debugfs->pdata, &clock);
        if (ret)
                return ret;

        *val = clock;

        return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(t3_fops, t3_get, NULL, "%llu\n");

static int t4_get(void *data, u64 *val)
{
        struct pci_ptm_debugfs *ptm_debugfs = data;
        u64 clock;
        int ret;

        if (!ptm_debugfs->ops->t4_read)
                return -EOPNOTSUPP;

        ret = ptm_debugfs->ops->t4_read(ptm_debugfs->pdata, &clock);
        if (ret)
                return ret;

        *val = clock;

        return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(t4_fops, t4_get, NULL, "%llu\n");

#define pcie_ptm_create_debugfs_file(pdata, mode, attr)                 \
        do {                                                            \
                if (ops->attr##_visible && ops->attr##_visible(pdata))  \
                        debugfs_create_file(#attr, mode, ptm_debugfs->debugfs, \
                                            ptm_debugfs, &attr##_fops); \
        } while (0)

/*
 * pcie_ptm_create_debugfs() - Create debugfs entries for the PTM context
 * @dev: PTM capable component device
 * @pdata: Private data of the PTM capable component device
 * @ops: PTM callback structure
 *
 * Create debugfs entries for exposing the PTM context of the PTM capable
 * components such as Root Complex and Endpoint controllers.
 *
 * Return: Pointer to 'struct pci_ptm_debugfs' if success, NULL otherwise.
 */
struct pci_ptm_debugfs *pcie_ptm_create_debugfs(struct device *dev, void *pdata,
                          const struct pcie_ptm_ops *ops)
{
        struct pci_ptm_debugfs *ptm_debugfs;
        char *dirname;
        int ret;

        /* Caller must provide check_capability() callback */
        if (!ops->check_capability)
                return NULL;

        /* Check for PTM capability before creating debugfs attributes */
        ret = ops->check_capability(pdata);
        if (!ret) {
                dev_dbg(dev, "PTM capability not present\n");
                return NULL;
        }

        ptm_debugfs = kzalloc_obj(*ptm_debugfs);
        if (!ptm_debugfs)
                return NULL;

        dirname = devm_kasprintf(dev, GFP_KERNEL, "pcie_ptm_%s", dev_name(dev));
        if (!dirname) {
                kfree(ptm_debugfs);
                return NULL;
        }

        ptm_debugfs->debugfs = debugfs_create_dir(dirname, NULL);
        ptm_debugfs->pdata = pdata;
        ptm_debugfs->ops = ops;
        mutex_init(&ptm_debugfs->lock);

        pcie_ptm_create_debugfs_file(pdata, 0644, context_update);
        pcie_ptm_create_debugfs_file(pdata, 0644, context_valid);
        pcie_ptm_create_debugfs_file(pdata, 0444, local_clock);
        pcie_ptm_create_debugfs_file(pdata, 0444, master_clock);
        pcie_ptm_create_debugfs_file(pdata, 0444, t1);
        pcie_ptm_create_debugfs_file(pdata, 0444, t2);
        pcie_ptm_create_debugfs_file(pdata, 0444, t3);
        pcie_ptm_create_debugfs_file(pdata, 0444, t4);

        return ptm_debugfs;
}
EXPORT_SYMBOL_GPL(pcie_ptm_create_debugfs);

/*
 * pcie_ptm_destroy_debugfs() - Destroy debugfs entries for the PTM context
 * @ptm_debugfs: Pointer to the PTM debugfs struct
 */
void pcie_ptm_destroy_debugfs(struct pci_ptm_debugfs *ptm_debugfs)
{
        if (!ptm_debugfs)
                return;

        mutex_destroy(&ptm_debugfs->lock);
        debugfs_remove_recursive(ptm_debugfs->debugfs);
        kfree(ptm_debugfs);
}
EXPORT_SYMBOL_GPL(pcie_ptm_destroy_debugfs);
#endif