/*
 * ARM Specific GTDT table Support
 *
 * Copyright (C) 2016, Linaro Ltd.
 * Author: Daniel Lezcano <daniel.lezcano@linaro.org>
 *         Fu Wei <fu.wei@linaro.org>
 *         Hanjun Guo <hanjun.guo@linaro.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/acpi.h>
#include <linux/init.h>
#include <linux/irqdomain.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>

#include <clocksource/arm_arch_timer.h>

#undef pr_fmt
#define pr_fmt(fmt) "ACPI GTDT: " fmt

/**
 * struct acpi_gtdt_descriptor - Store the key info of GTDT for all functions
 * @gtdt:       The pointer to the struct acpi_table_gtdt of GTDT table.
 * @gtdt_end:   The pointer to the end of GTDT table.
 * @platform_timer:     The pointer to the start of Platform Timer Structure
 *
 * The struct store the key info of GTDT table, it should be initialized by
 * acpi_gtdt_init.
 */
struct acpi_gtdt_descriptor {
        struct acpi_table_gtdt *gtdt;
        void *gtdt_end;
        void *platform_timer;
};

static struct acpi_gtdt_descriptor acpi_gtdt_desc __initdata;

static inline void *next_platform_timer(void *platform_timer)
{
        struct acpi_gtdt_header *gh = platform_timer;

        platform_timer += gh->length;
        if (platform_timer < acpi_gtdt_desc.gtdt_end)
                return platform_timer;

        return NULL;
}

#define for_each_platform_timer(_g)                             \
        for (_g = acpi_gtdt_desc.platform_timer; _g;    \
             _g = next_platform_timer(_g))

static inline bool is_timer_block(void *platform_timer)
{
        struct acpi_gtdt_header *gh = platform_timer;

        return gh->type == ACPI_GTDT_TYPE_TIMER_BLOCK;
}

static inline bool is_non_secure_watchdog(void *platform_timer)
{
        struct acpi_gtdt_header *gh = platform_timer;
        struct acpi_gtdt_watchdog *wd = platform_timer;

        if (gh->type != ACPI_GTDT_TYPE_WATCHDOG)
                return false;

        return !(wd->timer_flags & ACPI_GTDT_WATCHDOG_SECURE);
}

static int __init map_gt_gsi(u32 interrupt, u32 flags)
{
        int trigger, polarity;

        trigger = (flags & ACPI_GTDT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE
                        : ACPI_LEVEL_SENSITIVE;

        polarity = (flags & ACPI_GTDT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW
                        : ACPI_ACTIVE_HIGH;

        return acpi_register_gsi(NULL, interrupt, trigger, polarity);
}

/**
 * acpi_gtdt_map_ppi() - Map the PPIs of per-cpu arch_timer.
 * @type:       the type of PPI.
 *
 * Note: Secure state is not managed by the kernel on ARM64 systems.
 * So we only handle the non-secure timer PPIs,
 * ARCH_TIMER_PHYS_SECURE_PPI is treated as invalid type.
 *
 * Return: the mapped PPI value, 0 if error.
 */
int __init acpi_gtdt_map_ppi(int type)
{
        struct acpi_table_gtdt *gtdt = acpi_gtdt_desc.gtdt;

        switch (type) {
        case ARCH_TIMER_PHYS_NONSECURE_PPI:
                return map_gt_gsi(gtdt->non_secure_el1_interrupt,
                                  gtdt->non_secure_el1_flags);
        case ARCH_TIMER_VIRT_PPI:
                return map_gt_gsi(gtdt->virtual_timer_interrupt,
                                  gtdt->virtual_timer_flags);

        case ARCH_TIMER_HYP_PPI:
                return map_gt_gsi(gtdt->non_secure_el2_interrupt,
                                  gtdt->non_secure_el2_flags);
        default:
                pr_err("Failed to map timer interrupt: invalid type.\n");
        }

        return 0;
}

/**
 * acpi_gtdt_c3stop() - Got c3stop info from GTDT according to the type of PPI.
 * @type:       the type of PPI.
 *
 * Return: true if the timer HW state is lost when a CPU enters an idle state,
 * false otherwise
 */
bool __init acpi_gtdt_c3stop(int type)
{
        struct acpi_table_gtdt *gtdt = acpi_gtdt_desc.gtdt;

        switch (type) {
        case ARCH_TIMER_PHYS_NONSECURE_PPI:
                return !(gtdt->non_secure_el1_flags & ACPI_GTDT_ALWAYS_ON);

        case ARCH_TIMER_VIRT_PPI:
                return !(gtdt->virtual_timer_flags & ACPI_GTDT_ALWAYS_ON);

        case ARCH_TIMER_HYP_PPI:
                return !(gtdt->non_secure_el2_flags & ACPI_GTDT_ALWAYS_ON);

        default:
                pr_err("Failed to get c3stop info: invalid type.\n");
        }

        return false;
}

/**
 * acpi_gtdt_init() - Get the info of GTDT table to prepare for further init.
 * @table:                      The pointer to GTDT table.
 * @platform_timer_count:       It points to a integer variable which is used
 *                              for storing the number of platform timers.
 *                              This pointer could be NULL, if the caller
 *                              doesn't need this info.
 *
 * Return: 0 if success, -EINVAL if error.
 */
int __init acpi_gtdt_init(struct acpi_table_header *table,
                          int *platform_timer_count)
{
        void *platform_timer;
        struct acpi_table_gtdt *gtdt;

        gtdt = container_of(table, struct acpi_table_gtdt, header);
        acpi_gtdt_desc.gtdt = gtdt;
        acpi_gtdt_desc.gtdt_end = (void *)table + table->length;
        acpi_gtdt_desc.platform_timer = NULL;
        if (platform_timer_count)
                *platform_timer_count = 0;

        if (table->revision < 2) {
                pr_warn("Revision:%d doesn't support Platform Timers.\n",
                        table->revision);
                return 0;
        }

        if (!gtdt->platform_timer_count) {
                pr_debug("No Platform Timer.\n");
                return 0;
        }

        platform_timer = (void *)gtdt + gtdt->platform_timer_offset;
        if (platform_timer < (void *)table + sizeof(struct acpi_table_gtdt)) {
                pr_err(FW_BUG "invalid timer data.\n");
                return -EINVAL;
        }
        acpi_gtdt_desc.platform_timer = platform_timer;
        if (platform_timer_count)
                *platform_timer_count = gtdt->platform_timer_count;

        return 0;
}

static int __init gtdt_parse_timer_block(struct acpi_gtdt_timer_block *block,
                                         struct arch_timer_mem *timer_mem)
{
        int i;
        struct arch_timer_mem_frame *frame;
        struct acpi_gtdt_timer_entry *gtdt_frame;

        if (!block->timer_count) {
                pr_err(FW_BUG "GT block present, but frame count is zero.\n");
                return -ENODEV;
        }

        if (block->timer_count > ARCH_TIMER_MEM_MAX_FRAMES) {
                pr_err(FW_BUG "GT block lists %d frames, ACPI spec only allows 8\n",
                       block->timer_count);
                return -EINVAL;
        }

        timer_mem->cntctlbase = (phys_addr_t)block->block_address;
        /*
         * The CNTCTLBase frame is 4KB (register offsets 0x000 - 0xFFC).
         * See ARM DDI 0487A.k_iss10775, page I1-5129, Table I1-3
         * "CNTCTLBase memory map".
         */
        timer_mem->size = SZ_4K;

        gtdt_frame = (void *)block + block->timer_offset;
        if (gtdt_frame + block->timer_count != (void *)block + block->header.length)
                return -EINVAL;

        /*
         * Get the GT timer Frame data for every GT Block Timer
         */
        for (i = 0; i < block->timer_count; i++, gtdt_frame++) {
                if (gtdt_frame->common_flags & ACPI_GTDT_GT_IS_SECURE_TIMER)
                        continue;
                if (gtdt_frame->frame_number >= ARCH_TIMER_MEM_MAX_FRAMES ||
                    !gtdt_frame->base_address || !gtdt_frame->timer_interrupt)
                        goto error;

                frame = &timer_mem->frame[gtdt_frame->frame_number];

                /* duplicate frame */
                if (frame->valid)
                        goto error;

                frame->phys_irq = map_gt_gsi(gtdt_frame->timer_interrupt,
                                             gtdt_frame->timer_flags);
                if (frame->phys_irq <= 0) {
                        pr_warn("failed to map physical timer irq in frame %d.\n",
                                gtdt_frame->frame_number);
                        goto error;
                }

                if (gtdt_frame->virtual_timer_interrupt) {
                        frame->virt_irq =
                                map_gt_gsi(gtdt_frame->virtual_timer_interrupt,
                                           gtdt_frame->virtual_timer_flags);
                        if (frame->virt_irq <= 0) {
                                pr_warn("failed to map virtual timer irq in frame %d.\n",
                                        gtdt_frame->frame_number);
                                goto error;
                        }
                } else {
                        pr_debug("virtual timer in frame %d not implemented.\n",
                                 gtdt_frame->frame_number);
                }

                frame->cntbase = gtdt_frame->base_address;
                /*
                 * The CNTBaseN frame is 4KB (register offsets 0x000 - 0xFFC).
                 * See ARM DDI 0487A.k_iss10775, page I1-5130, Table I1-4
                 * "CNTBaseN memory map".
                 */
                frame->size = SZ_4K;
                frame->valid = true;
        }

        return 0;

error:
        do {
                if (gtdt_frame->common_flags & ACPI_GTDT_GT_IS_SECURE_TIMER ||
                    gtdt_frame->frame_number >= ARCH_TIMER_MEM_MAX_FRAMES)
                        continue;

                frame = &timer_mem->frame[gtdt_frame->frame_number];

                if (frame->phys_irq > 0)
                        acpi_unregister_gsi(gtdt_frame->timer_interrupt);
                frame->phys_irq = 0;

                if (frame->virt_irq > 0)
                        acpi_unregister_gsi(gtdt_frame->virtual_timer_interrupt);
                frame->virt_irq = 0;
        } while (i-- >= 0 && gtdt_frame--);

        return -EINVAL;
}

/**
 * acpi_arch_timer_mem_init() - Get the info of all GT blocks in GTDT table.
 * @timer_mem:  The pointer to the array of struct arch_timer_mem for returning
 *              the result of parsing. The element number of this array should
 *              be platform_timer_count(the total number of platform timers).
 * @timer_count: It points to a integer variable which is used for storing the
 *              number of GT blocks we have parsed.
 *
 * Return: 0 if success, -EINVAL/-ENODEV if error.
 */
int __init acpi_arch_timer_mem_init(struct arch_timer_mem *timer_mem,
                                    int *timer_count)
{
        int ret;
        void *platform_timer;

        *timer_count = 0;
        for_each_platform_timer(platform_timer) {
                if (is_timer_block(platform_timer)) {
                        ret = gtdt_parse_timer_block(platform_timer, timer_mem);
                        if (ret)
                                return ret;
                        timer_mem++;
                        (*timer_count)++;
                }
        }

        if (*timer_count)
                pr_info("found %d memory-mapped timer block(s).\n",
                        *timer_count);

        return 0;
}

/*
 * Initialize a SBSA generic Watchdog platform device info from GTDT
 */
static int __init gtdt_import_sbsa_gwdt(struct acpi_gtdt_watchdog *wd,
                                        int index)
{
        struct platform_device *pdev;
        int irq = map_gt_gsi(wd->timer_interrupt, wd->timer_flags);

        /*
         * According to SBSA specification the size of refresh and control
         * frames of SBSA Generic Watchdog is SZ_4K(Offset 0x000 – 0xFFF).
         */
        struct resource res[] = {
                DEFINE_RES_MEM(wd->control_frame_address, SZ_4K),
                DEFINE_RES_MEM(wd->refresh_frame_address, SZ_4K),
                DEFINE_RES_IRQ(irq),
        };
        int nr_res = ARRAY_SIZE(res);

        pr_debug("found a Watchdog (0x%llx/0x%llx gsi:%u flags:0x%x).\n",
                 wd->refresh_frame_address, wd->control_frame_address,
                 wd->timer_interrupt, wd->timer_flags);

        if (!(wd->refresh_frame_address && wd->control_frame_address)) {
                pr_err(FW_BUG "failed to get the Watchdog base address.\n");
                acpi_unregister_gsi(wd->timer_interrupt);
                return -EINVAL;
        }

        if (irq <= 0) {
                pr_warn("failed to map the Watchdog interrupt.\n");
                nr_res--;
        }

        /*
         * Add a platform device named "sbsa-gwdt" to match the platform driver.
         * "sbsa-gwdt": SBSA(Server Base System Architecture) Generic Watchdog
         * The platform driver can get device info below by matching this name.
         */
        pdev = platform_device_register_simple("sbsa-gwdt", index, res, nr_res);
        if (IS_ERR(pdev)) {
                acpi_unregister_gsi(wd->timer_interrupt);
                return PTR_ERR(pdev);
        }

        return 0;
}

static int __init gtdt_sbsa_gwdt_init(void)
{
        void *platform_timer;
        struct acpi_table_header *table;
        int ret, timer_count, gwdt_count = 0;

        if (acpi_disabled)
                return 0;

        if (ACPI_FAILURE(acpi_get_table(ACPI_SIG_GTDT, 0, &table)))
                return -EINVAL;

        /*
         * Note: Even though the global variable acpi_gtdt_desc has been
         * initialized by acpi_gtdt_init() while initializing the arch timers,
         * when we call this function to get SBSA watchdogs info from GTDT, the
         * pointers stashed in it are stale (since they are early temporary
         * mappings carried out before acpi_permanent_mmap is set) and we need
         * to re-initialize them with permanent mapped pointer values to let the
         * GTDT parsing possible.
         */
        ret = acpi_gtdt_init(table, &timer_count);
        if (ret || !timer_count)
                return ret;

        for_each_platform_timer(platform_timer) {
                if (is_non_secure_watchdog(platform_timer)) {
                        ret = gtdt_import_sbsa_gwdt(platform_timer, gwdt_count);
                        if (ret)
                                break;
                        gwdt_count++;
                }
        }

        if (gwdt_count)
                pr_info("found %d SBSA generic Watchdog(s).\n", gwdt_count);

        return ret;
}

device_initcall(gtdt_sbsa_gwdt_init);