/* 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 <asm/cio.h>
#include <linux/uaccess.h>

#define IDA_SIZE_LOG 12 /* 11 for 2k , 12 for 4k */
#define IDA_BLOCK_SIZE (1L<<IDA_SIZE_LOG)

/*
 * Test if an address/length pair needs an idal list.
 */
static inline int
idal_is_needed(void *vaddr, unsigned int length)
{
        return ((__pa(vaddr) + 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)
{
        return ((__pa(vaddr) & (IDA_BLOCK_SIZE-1)) + length +
                (IDA_BLOCK_SIZE-1)) >> IDA_SIZE_LOG;
}

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

        paddr = __pa(vaddr);
        cidaw = ((paddr & (IDA_BLOCK_SIZE-1)) + length + 
                 (IDA_BLOCK_SIZE-1)) >> IDA_SIZE_LOG;
        *idaws++ = paddr;
        paddr &= -IDA_BLOCK_SIZE;
        while (--cidaw > 0) {
                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;
        unsigned long *idal;

        if (ccw->flags & CCW_FLAG_IDA)
                return -EINVAL;
        nridaws = idal_nr_words(vaddr, ccw->count);
        if (nridaws > 0) {
                idal = kmalloc(nridaws * sizeof(unsigned long),
                               GFP_ATOMIC | GFP_DMA );
                if (idal == NULL)
                        return -ENOMEM;
                idal_create_words(idal, vaddr, ccw->count);
                ccw->flags |= CCW_FLAG_IDA;
                vaddr = idal;
        }
        ccw->cda = (__u32)(unsigned long) 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((void *)(unsigned long) ccw->cda);
                ccw->flags &= ~CCW_FLAG_IDA;
        }
        ccw->cda = 0;
}

/*
 * Idal buffer extension
 */
struct idal_buffer {
        size_t size;
        size_t page_order;
        void *data[0];
};

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

        nr_ptrs = (size + IDA_BLOCK_SIZE - 1) >> IDA_SIZE_LOG;
        nr_chunks = (4096 << page_order) >> IDA_SIZE_LOG;
        ib = kmalloc(struct_size(ib, data, nr_ptrs), GFP_DMA | GFP_KERNEL);
        if (ib == NULL)
                return ERR_PTR(-ENOMEM);
        ib->size = size;
        ib->page_order = page_order;
        for (i = 0; i < nr_ptrs; i++) {
                if ((i & (nr_chunks - 1)) != 0) {
                        ib->data[i] = ib->data[i-1] + IDA_BLOCK_SIZE;
                        continue;
                }
                ib->data[i] = (void *)
                        __get_free_pages(GFP_KERNEL, page_order);
                if (ib->data[i] != NULL)
                        continue;
                // Not enough memory
                while (i >= nr_chunks) {
                        i -= nr_chunks;
                        free_pages((unsigned long) ib->data[i],
                                   ib->page_order);
                }
                kfree(ib);
                return ERR_PTR(-ENOMEM);
        }
        return ib;
}

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

        nr_ptrs = (ib->size + IDA_BLOCK_SIZE - 1) >> IDA_SIZE_LOG;
        nr_chunks = (4096 << ib->page_order) >> IDA_SIZE_LOG;
        for (i = 0; i < nr_ptrs; i += nr_chunks)
                free_pages((unsigned long) ib->data[i], ib->page_order);
        kfree(ib);
}

/*
 * Test if a idal list is really needed.
 */
static inline int
__idal_buffer_is_needed(struct idal_buffer *ib)
{
        return ib->size > (4096ul << ib->page_order) ||
                idal_is_needed(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)
{
        if (__idal_buffer_is_needed(ib)) {
                // setup idals;
                ccw->cda = (u32)(addr_t) ib->data;
                ccw->flags |= CCW_FLAG_IDA;
        } else
                // we do not need idals - use direct addressing
                ccw->cda = (u32)(addr_t) ib->data[0];
        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;
        int i;

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

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

#endif