// SPDX-License-Identifier: GPL-2.0
/*
 * DMA memory management for framework level HCD code (hc_driver)
 *
 * This implementation plugs in through generic "usb_bus" level methods,
 * and should work with all USB controllers, regardless of bus type.
 *
 * Released under the GPLv2 only.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/mm.h>
#include <linux/io.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/genalloc.h>
#include <linux/usb.h>
#include <linux/usb/hcd.h>


/*
 * DMA-Coherent Buffers
 */

/* FIXME tune these based on pool statistics ... */
static size_t pool_max[HCD_BUFFER_POOLS] = {
        32, 128, 512, 2048,
};

void __init usb_init_pool_max(void)
{
        /*
         * The pool_max values must never be smaller than
         * ARCH_DMA_MINALIGN.
         */
        if (ARCH_DMA_MINALIGN <= 32)
                ;                       /* Original value is okay */
        else if (ARCH_DMA_MINALIGN <= 64)
                pool_max[0] = 64;
        else if (ARCH_DMA_MINALIGN <= 128)
                pool_max[0] = 0;        /* Don't use this pool */
        else
                BUILD_BUG();            /* We don't allow this */
}

/* SETUP primitives */

/**
 * hcd_buffer_create - initialize buffer pools
 * @hcd: the bus whose buffer pools are to be initialized
 *
 * Context: task context, might sleep
 *
 * Call this as part of initializing a host controller that uses the dma
 * memory allocators.  It initializes some pools of dma-coherent memory that
 * will be shared by all drivers using that controller.
 *
 * Call hcd_buffer_destroy() to clean up after using those pools.
 *
 * Return: 0 if successful. A negative errno value otherwise.
 */
int hcd_buffer_create(struct usb_hcd *hcd)
{
        char            name[16];
        int             i, size;

        if (hcd->localmem_pool || !hcd_uses_dma(hcd))
                return 0;

        for (i = 0; i < HCD_BUFFER_POOLS; i++) {
                size = pool_max[i];
                if (!size)
                        continue;
                snprintf(name, sizeof(name), "buffer-%d", size);
                hcd->pool[i] = dma_pool_create(name, hcd->self.sysdev,
                                size, size, 0);
                if (!hcd->pool[i]) {
                        hcd_buffer_destroy(hcd);
                        return -ENOMEM;
                }
        }
        return 0;
}


/**
 * hcd_buffer_destroy - deallocate buffer pools
 * @hcd: the bus whose buffer pools are to be destroyed
 *
 * Context: task context, might sleep
 *
 * This frees the buffer pools created by hcd_buffer_create().
 */
void hcd_buffer_destroy(struct usb_hcd *hcd)
{
        int i;

        if (!IS_ENABLED(CONFIG_HAS_DMA))
                return;

        for (i = 0; i < HCD_BUFFER_POOLS; i++) {
                dma_pool_destroy(hcd->pool[i]);
                hcd->pool[i] = NULL;
        }
}


/* sometimes alloc/free could use kmalloc with GFP_DMA, for
 * better sharing and to leverage mm/slab.c intelligence.
 */

void *hcd_buffer_alloc(
        struct usb_bus          *bus,
        size_t                  size,
        gfp_t                   mem_flags,
        dma_addr_t              *dma
)
{
        struct usb_hcd          *hcd = bus_to_hcd(bus);
        int                     i;

        if (size == 0)
                return NULL;

        if (hcd->localmem_pool)
                return gen_pool_dma_alloc(hcd->localmem_pool, size, dma);

        /* some USB hosts just use PIO */
        if (!hcd_uses_dma(hcd)) {
                *dma = ~(dma_addr_t) 0;
                return kmalloc(size, mem_flags);
        }

        for (i = 0; i < HCD_BUFFER_POOLS; i++) {
                if (size <= pool_max[i])
                        return dma_pool_alloc(hcd->pool[i], mem_flags, dma);
        }
        return dma_alloc_coherent(hcd->self.sysdev, size, dma, mem_flags);
}

void hcd_buffer_free(
        struct usb_bus          *bus,
        size_t                  size,
        void                    *addr,
        dma_addr_t              dma
)
{
        struct usb_hcd          *hcd = bus_to_hcd(bus);
        int                     i;

        if (!addr)
                return;

        if (hcd->localmem_pool) {
                gen_pool_free(hcd->localmem_pool, (unsigned long)addr, size);
                return;
        }

        if (!hcd_uses_dma(hcd)) {
                kfree(addr);
                return;
        }

        for (i = 0; i < HCD_BUFFER_POOLS; i++) {
                if (size <= pool_max[i]) {
                        dma_pool_free(hcd->pool[i], addr, dma);
                        return;
                }
        }
        dma_free_coherent(hcd->self.sysdev, size, addr, dma);
}

void *hcd_buffer_alloc_pages(struct usb_hcd *hcd,
                size_t size, gfp_t mem_flags, dma_addr_t *dma)
{
        if (size == 0)
                return NULL;

        if (hcd->localmem_pool)
                return gen_pool_dma_alloc_align(hcd->localmem_pool,
                                size, dma, PAGE_SIZE);

        /* some USB hosts just use PIO */
        if (!hcd_uses_dma(hcd)) {
                *dma = DMA_MAPPING_ERROR;
                return (void *)__get_free_pages(mem_flags,
                                get_order(size));
        }

        return dma_alloc_coherent(hcd->self.sysdev,
                        size, dma, mem_flags);
}

void hcd_buffer_free_pages(struct usb_hcd *hcd,
                size_t size, void *addr, dma_addr_t dma)
{
        if (!addr)
                return;

        if (hcd->localmem_pool) {
                gen_pool_free(hcd->localmem_pool,
                                (unsigned long)addr, size);
                return;
        }

        if (!hcd_uses_dma(hcd)) {
                free_pages((unsigned long)addr, get_order(size));
                return;
        }

        dma_free_coherent(hcd->self.sysdev, size, addr, dma);
}