/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Author(s)......: Holger Smolinski <Holger.Smolinski@de.ibm.com>
 *                  Martin Schwidefsky <schwidefsky@de.ibm.com>
 * Bugreports.to..: <Linux390@de.ibm.com>
 * Copyright IBM Corp. 2000
 *
 * History of changes
 * 07/24/00 new file
 * 05/04/02 code restructuring.
 */

#ifndef _S390_IDALS_H
#define _S390_IDALS_H

#include <linux/errno.h>
#include <linux/err.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <asm/dma-types.h>
#include <asm/cio.h>

#define IDA_SIZE_SHIFT          12
#define IDA_BLOCK_SIZE          (1UL << IDA_SIZE_SHIFT)

#define IDA_2K_SIZE_SHIFT       11
#define IDA_2K_BLOCK_SIZE       (1UL << IDA_2K_SIZE_SHIFT)

/*
 * Test if an address/length pair needs an idal list.
 */
static inline bool idal_is_needed(void *vaddr, unsigned int length)
{
        dma64_t paddr = virt_to_dma64(vaddr);

        return (((__force unsigned long)(paddr) + length - 1) >> 31) != 0;
}

/*
 * Return the number of idal words needed for an address/length pair.
 */
static inline unsigned int idal_nr_words(void *vaddr, unsigned int length)
{
        unsigned int cidaw;

        cidaw = (unsigned long)vaddr & (IDA_BLOCK_SIZE - 1);
        cidaw += length + IDA_BLOCK_SIZE - 1;
        cidaw >>= IDA_SIZE_SHIFT;
        return cidaw;
}

/*
 * Return the number of 2K IDA words needed for an address/length pair.
 */
static inline unsigned int idal_2k_nr_words(void *vaddr, unsigned int length)
{
        unsigned int cidaw;

        cidaw = (unsigned long)vaddr & (IDA_2K_BLOCK_SIZE - 1);
        cidaw += length + IDA_2K_BLOCK_SIZE - 1;
        cidaw >>= IDA_2K_SIZE_SHIFT;
        return cidaw;
}

/*
 * Create the list of idal words for an address/length pair.
 */
static inline dma64_t *idal_create_words(dma64_t *idaws, void *vaddr, unsigned int length)
{
        dma64_t paddr = virt_to_dma64(vaddr);
        unsigned int cidaw;

        *idaws++ = paddr;
        cidaw = idal_nr_words(vaddr, length);
        paddr = dma64_and(paddr, -IDA_BLOCK_SIZE);
        while (--cidaw > 0) {
                paddr = dma64_add(paddr, IDA_BLOCK_SIZE);
                *idaws++ = paddr;
        }
        return idaws;
}

/*
 * Sets the address of the data in CCW.
 * If necessary it allocates an IDAL and sets the appropriate flags.
 */
static inline int set_normalized_cda(struct ccw1 *ccw, void *vaddr)
{
        unsigned int nridaws;
        dma64_t *idal;

        if (ccw->flags & CCW_FLAG_IDA)
                return -EINVAL;
        nridaws = idal_nr_words(vaddr, ccw->count);
        if (nridaws > 0) {
                idal = kzalloc_objs(*idal, nridaws, GFP_ATOMIC | GFP_DMA);
                if (!idal)
                        return -ENOMEM;
                idal_create_words(idal, vaddr, ccw->count);
                ccw->flags |= CCW_FLAG_IDA;
                vaddr = idal;
        }
        ccw->cda = virt_to_dma32(vaddr);
        return 0;
}

/*
 * Releases any allocated IDAL related to the CCW.
 */
static inline void clear_normalized_cda(struct ccw1 *ccw)
{
        if (ccw->flags & CCW_FLAG_IDA) {
                kfree(dma32_to_virt(ccw->cda));
                ccw->flags &= ~CCW_FLAG_IDA;
        }
        ccw->cda = 0;
}

/*
 * Idal buffer extension
 */
struct idal_buffer {
        size_t size;
        size_t page_order;
        dma64_t data[];
};

/*
 * Allocate an idal buffer
 */
static inline struct idal_buffer *idal_buffer_alloc(size_t size, int page_order)
{
        int nr_chunks, nr_ptrs, i;
        struct idal_buffer *ib;
        void *vaddr;

        nr_ptrs = (size + IDA_BLOCK_SIZE - 1) >> IDA_SIZE_SHIFT;
        nr_chunks = (PAGE_SIZE << page_order) >> IDA_SIZE_SHIFT;
        ib = kmalloc_flex(*ib, data, nr_ptrs, GFP_DMA | GFP_KERNEL);
        if (!ib)
                return ERR_PTR(-ENOMEM);
        ib->size = size;
        ib->page_order = page_order;
        for (i = 0; i < nr_ptrs; i++) {
                if (i & (nr_chunks - 1)) {
                        ib->data[i] = dma64_add(ib->data[i - 1], IDA_BLOCK_SIZE);
                        continue;
                }
                vaddr = (void *)__get_free_pages(GFP_KERNEL, page_order);
                if (!vaddr)
                        goto error;
                ib->data[i] = virt_to_dma64(vaddr);
        }
        return ib;
error:
        while (i >= nr_chunks) {
                i -= nr_chunks;
                vaddr = dma64_to_virt(ib->data[i]);
                free_pages((unsigned long)vaddr, ib->page_order);
        }
        kfree(ib);
        return ERR_PTR(-ENOMEM);
}

/*
 * Free an idal buffer.
 */
static inline void idal_buffer_free(struct idal_buffer *ib)
{
        int nr_chunks, nr_ptrs, i;
        void *vaddr;

        nr_ptrs = (ib->size + IDA_BLOCK_SIZE - 1) >> IDA_SIZE_SHIFT;
        nr_chunks = (PAGE_SIZE << ib->page_order) >> IDA_SIZE_SHIFT;
        for (i = 0; i < nr_ptrs; i += nr_chunks) {
                vaddr = dma64_to_virt(ib->data[i]);
                free_pages((unsigned long)vaddr, ib->page_order);
        }
        kfree(ib);
}

/*
 * Allocate an array of IDAL buffers to cover a total data size of @size. The
 * resulting array is null-terminated.
 *
 * The amount of individual IDAL buffers is determined based on @size.
 * Each IDAL buffer can have a maximum size of @CCW_MAX_BYTE_COUNT.
 */
static inline struct idal_buffer **idal_buffer_array_alloc(size_t size, int page_order)
{
        struct idal_buffer **ibs;
        size_t ib_size; /* Size of a single idal buffer */
        int count; /* Amount of individual idal buffers */
        int i;

        count = (size + CCW_MAX_BYTE_COUNT - 1) / CCW_MAX_BYTE_COUNT;
        ibs = kmalloc_objs(*ibs, count + 1);
        for (i = 0; i < count; i++) {
                /* Determine size for the current idal buffer */
                ib_size = min(size, CCW_MAX_BYTE_COUNT);
                size -= ib_size;
                ibs[i] = idal_buffer_alloc(ib_size, page_order);
                if (IS_ERR(ibs[i])) {
                        while (i--)
                                idal_buffer_free(ibs[i]);
                        kfree(ibs);
                        ibs = NULL;
                        return ERR_PTR(-ENOMEM);
                }
        }
        ibs[i] = NULL;
        return ibs;
}

/*
 * Free array of IDAL buffers
 */
static inline void idal_buffer_array_free(struct idal_buffer ***ibs)
{
        struct idal_buffer **p;

        if (!ibs || !*ibs)
                return;
        for (p = *ibs; *p; p++)
                idal_buffer_free(*p);
        kfree(*ibs);
        *ibs = NULL;
}

/*
 * Determine size of IDAL buffer array
 */
static inline int idal_buffer_array_size(struct idal_buffer **ibs)
{
        int size = 0;

        while (ibs && *ibs) {
                size++;
                ibs++;
        }
        return size;
}

/*
 * Determine total data size covered by IDAL buffer array
 */
static inline size_t idal_buffer_array_datasize(struct idal_buffer **ibs)
{
        size_t size = 0;

        while (ibs && *ibs) {
                size += (*ibs)->size;
                ibs++;
        }
        return size;
}

/*
 * Test if a idal list is really needed.
 */
static inline bool __idal_buffer_is_needed(struct idal_buffer *ib)
{
        if (ib->size > (PAGE_SIZE << ib->page_order))
                return true;
        return idal_is_needed(dma64_to_virt(ib->data[0]), ib->size);
}

/*
 * Set channel data address to idal buffer.
 */
static inline void idal_buffer_set_cda(struct idal_buffer *ib, struct ccw1 *ccw)
{
        void *vaddr;

        if (__idal_buffer_is_needed(ib)) {
                /* Setup idals */
                ccw->cda = virt_to_dma32(ib->data);
                ccw->flags |= CCW_FLAG_IDA;
        } else {
                /*
                 * No idals needed - use direct addressing. Convert from
                 * dma64_t to virt and then to dma32_t only because of type
                 * checking. The physical address is known to be below 2GB.
                 */
                vaddr = dma64_to_virt(ib->data[0]);
                ccw->cda = virt_to_dma32(vaddr);
        }
        ccw->count = ib->size;
}

/*
 * Copy count bytes from an idal buffer to user memory
 */
static inline size_t idal_buffer_to_user(struct idal_buffer *ib, void __user *to, size_t count)
{
        size_t left;
        void *vaddr;
        int i;

        BUG_ON(count > ib->size);
        for (i = 0; count > IDA_BLOCK_SIZE; i++) {
                vaddr = dma64_to_virt(ib->data[i]);
                left = copy_to_user(to, vaddr, IDA_BLOCK_SIZE);
                if (left)
                        return left + count - IDA_BLOCK_SIZE;
                to = (void __user *)to + IDA_BLOCK_SIZE;
                count -= IDA_BLOCK_SIZE;
        }
        vaddr = dma64_to_virt(ib->data[i]);
        return copy_to_user(to, vaddr, count);
}

/*
 * Copy count bytes from user memory to an idal buffer
 */
static inline size_t idal_buffer_from_user(struct idal_buffer *ib, const void __user *from, size_t count)
{
        size_t left;
        void *vaddr;
        int i;

        BUG_ON(count > ib->size);
        for (i = 0; count > IDA_BLOCK_SIZE; i++) {
                vaddr = dma64_to_virt(ib->data[i]);
                left = copy_from_user(vaddr, from, IDA_BLOCK_SIZE);
                if (left)
                        return left + count - IDA_BLOCK_SIZE;
                from = (void __user *)from + IDA_BLOCK_SIZE;
                count -= IDA_BLOCK_SIZE;
        }
        vaddr = dma64_to_virt(ib->data[i]);
        return copy_from_user(vaddr, from, count);
}

#endif