/*
 * Generic on-chip SRAM allocation driver
 *
 * Copyright (C) 2012 Philipp Zabel, Pengutronix
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301, USA.
 */

#include <linux/clk.h>
#include <linux/genalloc.h>
#include <linux/io.h>
#include <linux/list_sort.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#define SRAM_GRANULARITY        32

struct sram_partition {
        void __iomem *base;

        struct gen_pool *pool;
        struct bin_attribute battr;
        struct mutex lock;
};

struct sram_dev {
        struct device *dev;
        void __iomem *virt_base;

        struct gen_pool *pool;
        struct clk *clk;

        struct sram_partition *partition;
        u32 partitions;
};

struct sram_reserve {
        struct list_head list;
        u32 start;
        u32 size;
        bool export;
        bool pool;
        const char *label;
};

static ssize_t sram_read(struct file *filp, struct kobject *kobj,
                         struct bin_attribute *attr,
                         char *buf, loff_t pos, size_t count)
{
        struct sram_partition *part;

        part = container_of(attr, struct sram_partition, battr);

        mutex_lock(&part->lock);
        memcpy_fromio(buf, part->base + pos, count);
        mutex_unlock(&part->lock);

        return count;
}

static ssize_t sram_write(struct file *filp, struct kobject *kobj,
                          struct bin_attribute *attr,
                          char *buf, loff_t pos, size_t count)
{
        struct sram_partition *part;

        part = container_of(attr, struct sram_partition, battr);

        mutex_lock(&part->lock);
        memcpy_toio(part->base + pos, buf, count);
        mutex_unlock(&part->lock);

        return count;
}

static int sram_add_pool(struct sram_dev *sram, struct sram_reserve *block,
                         phys_addr_t start, struct sram_partition *part)
{
        int ret;

        part->pool = devm_gen_pool_create(sram->dev, ilog2(SRAM_GRANULARITY),
                                          NUMA_NO_NODE, block->label);
        if (IS_ERR(part->pool))
                return PTR_ERR(part->pool);

        ret = gen_pool_add_virt(part->pool, (unsigned long)part->base, start,
                                block->size, NUMA_NO_NODE);
        if (ret < 0) {
                dev_err(sram->dev, "failed to register subpool: %d\n", ret);
                return ret;
        }

        return 0;
}

static int sram_add_export(struct sram_dev *sram, struct sram_reserve *block,
                           phys_addr_t start, struct sram_partition *part)
{
        sysfs_bin_attr_init(&part->battr);
        part->battr.attr.name = devm_kasprintf(sram->dev, GFP_KERNEL,
                                               "%llx.sram",
                                               (unsigned long long)start);
        if (!part->battr.attr.name)
                return -ENOMEM;

        part->battr.attr.mode = S_IRUSR | S_IWUSR;
        part->battr.read = sram_read;
        part->battr.write = sram_write;
        part->battr.size = block->size;

        return device_create_bin_file(sram->dev, &part->battr);
}

static int sram_add_partition(struct sram_dev *sram, struct sram_reserve *block,
                              phys_addr_t start)
{
        int ret;
        struct sram_partition *part = &sram->partition[sram->partitions];

        mutex_init(&part->lock);
        part->base = sram->virt_base + block->start;

        if (block->pool) {
                ret = sram_add_pool(sram, block, start, part);
                if (ret)
                        return ret;
        }
        if (block->export) {
                ret = sram_add_export(sram, block, start, part);
                if (ret)
                        return ret;
        }
        sram->partitions++;

        return 0;
}

static void sram_free_partitions(struct sram_dev *sram)
{
        struct sram_partition *part;

        if (!sram->partitions)
                return;

        part = &sram->partition[sram->partitions - 1];
        for (; sram->partitions; sram->partitions--, part--) {
                if (part->battr.size)
                        device_remove_bin_file(sram->dev, &part->battr);

                if (part->pool &&
                    gen_pool_avail(part->pool) < gen_pool_size(part->pool))
                        dev_err(sram->dev, "removed pool while SRAM allocated\n");
        }
}

static int sram_reserve_cmp(void *priv, struct list_head *a,
                                        struct list_head *b)
{
        struct sram_reserve *ra = list_entry(a, struct sram_reserve, list);
        struct sram_reserve *rb = list_entry(b, struct sram_reserve, list);

        return ra->start - rb->start;
}

static int sram_reserve_regions(struct sram_dev *sram, struct resource *res)
{
        struct device_node *np = sram->dev->of_node, *child;
        unsigned long size, cur_start, cur_size;
        struct sram_reserve *rblocks, *block;
        struct list_head reserve_list;
        unsigned int nblocks, exports = 0;
        const char *label;
        int ret = 0;

        INIT_LIST_HEAD(&reserve_list);

        size = resource_size(res);

        /*
         * We need an additional block to mark the end of the memory region
         * after the reserved blocks from the dt are processed.
         */
        nblocks = (np) ? of_get_available_child_count(np) + 1 : 1;
        rblocks = kzalloc((nblocks) * sizeof(*rblocks), GFP_KERNEL);
        if (!rblocks)
                return -ENOMEM;

        block = &rblocks[0];
        for_each_available_child_of_node(np, child) {
                struct resource child_res;

                ret = of_address_to_resource(child, 0, &child_res);
                if (ret < 0) {
                        dev_err(sram->dev,
                                "could not get address for node %s\n",
                                child->full_name);
                        goto err_chunks;
                }

                if (child_res.start < res->start || child_res.end > res->end) {
                        dev_err(sram->dev,
                                "reserved block %s outside the sram area\n",
                                child->full_name);
                        ret = -EINVAL;
                        goto err_chunks;
                }

                block->start = child_res.start - res->start;
                block->size = resource_size(&child_res);
                list_add_tail(&block->list, &reserve_list);

                if (of_find_property(child, "export", NULL))
                        block->export = true;

                if (of_find_property(child, "pool", NULL))
                        block->pool = true;

                if ((block->export || block->pool) && block->size) {
                        exports++;

                        label = NULL;
                        ret = of_property_read_string(child, "label", &label);
                        if (ret && ret != -EINVAL) {
                                dev_err(sram->dev,
                                        "%s has invalid label name\n",
                                        child->full_name);
                                goto err_chunks;
                        }
                        if (!label)
                                label = child->name;

                        block->label = devm_kstrdup(sram->dev,
                                                    label, GFP_KERNEL);
                        if (!block->label)
                                goto err_chunks;

                        dev_dbg(sram->dev, "found %sblock '%s' 0x%x-0x%x\n",
                                block->export ? "exported " : "", block->label,
                                block->start, block->start + block->size);
                } else {
                        dev_dbg(sram->dev, "found reserved block 0x%x-0x%x\n",
                                block->start, block->start + block->size);
                }

                block++;
        }
        child = NULL;

        /* the last chunk marks the end of the region */
        rblocks[nblocks - 1].start = size;
        rblocks[nblocks - 1].size = 0;
        list_add_tail(&rblocks[nblocks - 1].list, &reserve_list);

        list_sort(NULL, &reserve_list, sram_reserve_cmp);

        if (exports) {
                sram->partition = devm_kzalloc(sram->dev,
                                       exports * sizeof(*sram->partition),
                                       GFP_KERNEL);
                if (!sram->partition) {
                        ret = -ENOMEM;
                        goto err_chunks;
                }
        }

        cur_start = 0;
        list_for_each_entry(block, &reserve_list, list) {
                /* can only happen if sections overlap */
                if (block->start < cur_start) {
                        dev_err(sram->dev,
                                "block at 0x%x starts after current offset 0x%lx\n",
                                block->start, cur_start);
                        ret = -EINVAL;
                        sram_free_partitions(sram);
                        goto err_chunks;
                }

                if ((block->export || block->pool) && block->size) {
                        ret = sram_add_partition(sram, block,
                                                 res->start + block->start);
                        if (ret) {
                                sram_free_partitions(sram);
                                goto err_chunks;
                        }
                }

                /* current start is in a reserved block, so continue after it */
                if (block->start == cur_start) {
                        cur_start = block->start + block->size;
                        continue;
                }

                /*
                 * allocate the space between the current starting
                 * address and the following reserved block, or the
                 * end of the region.
                 */
                cur_size = block->start - cur_start;

                dev_dbg(sram->dev, "adding chunk 0x%lx-0x%lx\n",
                        cur_start, cur_start + cur_size);

                ret = gen_pool_add_virt(sram->pool,
                                (unsigned long)sram->virt_base + cur_start,
                                res->start + cur_start, cur_size, -1);
                if (ret < 0) {
                        sram_free_partitions(sram);
                        goto err_chunks;
                }

                /* next allocation after this reserved block */
                cur_start = block->start + block->size;
        }

 err_chunks:
        if (child)
                of_node_put(child);

        kfree(rblocks);

        return ret;
}

static int sram_probe(struct platform_device *pdev)
{
        struct sram_dev *sram;
        struct resource *res;
        size_t size;
        int ret;

        sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
        if (!sram)
                return -ENOMEM;

        sram->dev = &pdev->dev;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res) {
                dev_err(sram->dev, "found no memory resource\n");
                return -EINVAL;
        }

        size = resource_size(res);

        if (!devm_request_mem_region(sram->dev, res->start, size, pdev->name)) {
                dev_err(sram->dev, "could not request region for resource\n");
                return -EBUSY;
        }

        if (of_property_read_bool(pdev->dev.of_node, "no-memory-wc"))
                sram->virt_base = devm_ioremap(sram->dev, res->start, size);
        else
                sram->virt_base = devm_ioremap_wc(sram->dev, res->start, size);
        if (IS_ERR(sram->virt_base))
                return PTR_ERR(sram->virt_base);

        sram->pool = devm_gen_pool_create(sram->dev, ilog2(SRAM_GRANULARITY),
                                          NUMA_NO_NODE, NULL);
        if (IS_ERR(sram->pool))
                return PTR_ERR(sram->pool);

        ret = sram_reserve_regions(sram, res);
        if (ret)
                return ret;

        sram->clk = devm_clk_get(sram->dev, NULL);
        if (IS_ERR(sram->clk))
                sram->clk = NULL;
        else
                clk_prepare_enable(sram->clk);

        platform_set_drvdata(pdev, sram);

        dev_dbg(sram->dev, "SRAM pool: %zu KiB @ 0x%p\n",
                gen_pool_size(sram->pool) / 1024, sram->virt_base);

        return 0;
}

static int sram_remove(struct platform_device *pdev)
{
        struct sram_dev *sram = platform_get_drvdata(pdev);

        sram_free_partitions(sram);

        if (gen_pool_avail(sram->pool) < gen_pool_size(sram->pool))
                dev_err(sram->dev, "removed while SRAM allocated\n");

        if (sram->clk)
                clk_disable_unprepare(sram->clk);

        return 0;
}

#ifdef CONFIG_OF
static const struct of_device_id sram_dt_ids[] = {
        { .compatible = "mmio-sram" },
        {}
};
#endif

static struct platform_driver sram_driver = {
        .driver = {
                .name = "sram",
                .of_match_table = of_match_ptr(sram_dt_ids),
        },
        .probe = sram_probe,
        .remove = sram_remove,
};

static int __init sram_init(void)
{
        return platform_driver_register(&sram_driver);
}

postcore_initcall(sram_init);