/*
 *  cma_driver.c - Broadcom STB platform CMA driver
 *
 *  Copyright (C) 2009 - 2013 Broadcom Corporation
 *
 *  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, 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; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#define pr_fmt(fmt) "cma_driver: " fmt

#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_fdt.h>
#include <linux/cdev.h>
#include <linux/dma-mapping.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/brcmstb/cma_driver.h>
#include <linux/mmzone.h>
#include <linux/vmalloc.h>
#include <linux/memblock.h>
#include <linux/device.h>
#include <linux/bitmap.h>
#include <linux/highmem.h>
#include <linux/dma-contiguous.h>
#include <linux/sizes.h>
#include <linux/vme.h>
#include <asm/div64.h>
#include <asm/setup.h>

struct cma_devs_list {
	struct list_head list;
	struct cma_dev *cma_dev;
};

struct cma_root_dev {
	u32 mmap_type;
	struct cdev cdev;
	struct device *dev;
	struct cma_devs_list cma_devs;
};

struct cma_pdev_data {
	phys_addr_t start;
	phys_addr_t size;
	int do_prealloc;
	struct cma *cma_area;
};

struct cma_region_rsv_data {
	int nr_regions_valid;
	struct cma_pdev_data regions[NR_BANKS];
	long long unsigned prm_kern_rsv_mb;
	long long unsigned prm_low_lim_mb;
	int prm_low_kern_rsv_pct;
};

/* CMA region reservation */

static struct cma_region_rsv_data cma_data __initdata = {
	.prm_kern_rsv_mb = 256 << 20,
	.prm_low_lim_mb = 32 << 20,
	.prm_low_kern_rsv_pct = 20,
};

enum scan_bitmap_op {
	GET_NUM_REGIONS = 0,
	GET_REGION_INFO,
};

/*
 * The default kernel reservation on systems with low and high-memory. The
 * size of the memblock minus this variable will be given to CMA
 */
static int __init cma_kern_rsv_set(char *p)
{
	cma_data.prm_kern_rsv_mb = memparse(p, NULL);
	return !cma_data.prm_kern_rsv_mb ? -EINVAL : 0;
}
early_param("brcm_cma_kern_rsv", cma_kern_rsv_set);

/*
 * The lowest low-memory memblock size needed in order to reserve a cma region
 * on systems with no high-memory.
 */
static int __init cma_mb_low_lim_set(char *p)
{
	cma_data.prm_low_lim_mb = memparse(p, NULL);
	return !cma_data.prm_low_lim_mb ? -EINVAL : 0;
}
early_param("brcm_cma_mb_low_lim", cma_mb_low_lim_set);

/*
 * The percentage of memory reserved for the kernel on systems with no
 * high-memory.
 */
static int __init cma_low_kern_rsv_pct_set(char *p)
{
	return (get_option(&p, &cma_data.prm_low_kern_rsv_pct) == 0) ?
		-EINVAL : 0;
}
early_param("brcm_cma_low_kern_rsv_pct", cma_low_kern_rsv_pct_set);

/*
 * Determine how many bytes of memory have been reserved in the DT
 * reserve map (/memreserve/).
 *
 * Note: It is expected that the only user of /memreserve/ is the bolt
 * 'splashmem' implementation. All other users that require contiguous memory
 * should use the standard CMA interfaces.
 */
static u32 __init parse_static_rsv_entries(const u64 range_start,
						const u64 range_size)
{
	u64 *rsv_map;
	u32 bytes_reserved = 0;
	const u64 range_end = range_start + range_size;

	if (!initial_boot_params) {
		pr_err("no fdt found\n");
		return 0;
	}

	rsv_map = ((void *)initial_boot_params) +
			be32_to_cpu(initial_boot_params->off_mem_rsvmap);
	for (;;) {
		const u64 base = be64_to_cpup(rsv_map++);
		const u64 size = be64_to_cpup(rsv_map++);
		const u64 end = base + size;

		if (!size)
			break;

		/* 'splashmem' is expected to only carve memory out at the end
		 * of the MEMC. All other reservations should modify the
		 * DT 'memory' node so that the automatic CMA reservation
		 * code doesn't fail.
		 */
		if (base >= range_start && base < range_end) {
			if (end >= range_start) {
				if (end < range_end)
					bytes_reserved += size;
				else
					bytes_reserved += range_end - base;
			}
		}
	}

	return bytes_reserved;
}

static int __init cma_calc_rsv_range(int bank_nr, phys_addr_t *size)
{
	/* This is the alignment used in dma_contiguous_reserve_area() */
	const phys_addr_t alignment =
			PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
	u64 total = 0;
	u32 bytes_reserved;
	struct membank *bank = &meminfo.bank[bank_nr];

	/*
	 * In DT, the 'reg' property in the 'memory' node is typically
	 * arranged as follows:
	 *
	 *	<base0 size0 base1 size1 [...] baseN sizeN>
	 *
	 * where N = the number of logical partitions in the memory map.
	 *
	 * The 'logical partitions' are typically memory controllers.
	 *
	 * According to ARM DEN 0001C, systems typically populate DRAM at high
	 * PAs in the physical address space. However, system limitations
	 * require placement of DRAM at low PAs. To that end, there is a need
	 * to provide contiguous memory in low-memory regions, to support the
	 * needs of system peripherals.
	 *
	 * Further, the current ARM kernel exploits large linear mappings in
	 * low-memory, to reduce TLB pressure and increase overall system
	 * performance. In a 3G/1G user/kernel memory split, the 1G portion of
	 * kernel address space is further broken down into a low and high
	 * memory region. The high-memory region is defined by the kernel
	 * to be used for vmalloc (see arch/arm/mm/mmu.c).
	 *
	 * The code below will workaround the aforementioned demands on
	 * low-memory (which resides in bank_nr = 0), and any special
	 * kernel-specific boundaries.
	 *
	 */
	if (bank_nr == 0) {
		if ((meminfo.nr_banks == 1) && !bank->highmem) {
			u32 rem;
			u64 tmp;

			if (bank->size < cma_data.prm_low_lim_mb) {
				/* don't bother */
				pr_err("low memory block too small\n");
				return -EINVAL;
			}

			/* kernel reserves X percent, cma gets the rest */
			tmp = ((u64)bank->size) *
					(100 - cma_data.prm_low_kern_rsv_pct);
			rem = do_div(tmp, 100);
			total = tmp + rem;
		} else {
			if (bank->size >= cma_data.prm_kern_rsv_mb) {
				total = bank->size - cma_data.prm_kern_rsv_mb;
			} else {
				pr_debug("bank start=0x%pa size=0x%pa is smaller than cma_data.prm_kern_rsv_mb=0x%llx - skipping\n",
					&bank->start,
					&bank->size,
					cma_data.prm_kern_rsv_mb);
				return -EINVAL;
			}
		}
	} else if (bank->start >= VME_A32_MAX && bank->size > SZ_64M) {
		/*
		 * Nexus can't use the address extension range yet, just reserve
		 * 64 MiB in these areas until we have a firmer specification.
		 */
		total = SZ_64M;
	} else {
		total = bank->size;
	}

	/* Subtract the size of any DT-based (/memreserve/) memblock
	 * reservations that overlap with the current range from the total.
	 */
	bytes_reserved = parse_static_rsv_entries(bank->start, total);
	if (total >= bytes_reserved)
		total -= bytes_reserved;

	*size = round_down(total, alignment);

	return 0;
}

/*
 * Create maximum-sized CMA regions for each memblock.
 *
 * This function MUST be called by the platform 'reserve' function.
 *
 * Notes:
 * - Memblocks are initially generated based on the ranges specified in the
 *   DT memory node.
 *
 * - After initialization by the DT memory node, a memblock may be split,
 *   depending on whether it spans a special memory region (such as the
 *   arm_lowmem_limit).
 *
 * - The kernel lives in valuable low-memory. Therefore, it is not possible to
 *   create a CMA region which spans the entire low-memory memblock. Thus a
 *   "fudge" constant, param_cma_kern_rsv, is used to adjust the low-memory
 *   CMA region.
 */
void __init cma_reserve(void)
{
	int rc;
	int iter;

	for_each_bank(iter, &meminfo) {
		struct cma *tmp_cma_area;
		struct membank *bank = &meminfo.bank[iter];
		phys_addr_t size = 0;
		phys_addr_t bank_end = bank->start + bank->size;

		if (cma_data.nr_regions_valid == NR_BANKS)
			pr_err("cma_data.regions overflow\n");

		if (cma_calc_rsv_range(iter, &size))
			continue;

		pr_debug("try to reserve 0x%pa in 0x%pa-0x%pa\n", &size,
				&bank->start, &bank_end);
		rc = dma_contiguous_reserve_area(size, bank->start,
				bank_end, &tmp_cma_area);
		if (rc) {
			pr_err("reservation failed (bank=0x%pa-0x%pa,size=0x%pa,rc=%d)\n",
				&bank->start, &bank_end, &size, rc);
			/*
			 * This will help us see if a stray memory reservation
			 * is fragmenting the memblock.
			 */
			memblock_debug = 1;
			memblock_dump_all();
			memblock_debug = 0;
		} else {
			cma_data.regions[cma_data.nr_regions_valid].start =
				PFN_PHYS(tmp_cma_area->base_pfn);
			cma_data.regions[cma_data.nr_regions_valid].size = size;

			/* Pre-allocate all regions */
			cma_data.regions[cma_data.nr_regions_valid].do_prealloc
				= 1;
			cma_data.regions[cma_data.nr_regions_valid].cma_area =
				tmp_cma_area;
			cma_data.nr_regions_valid++;
		}
	}
}

static struct platform_device * __init cma_register_dev_one(int id,
	int region_idx)
{
	struct platform_device *pdev;

	pdev = platform_device_register_data(NULL, "brcm-cma", id,
		&cma_data.regions[region_idx], sizeof(struct cma_pdev_data));
	if (!pdev) {
		pr_err("couldn't register pdev for %d,0x%pa,0x%pa\n", id,
			&cma_data.regions[region_idx].start,
			&cma_data.regions[region_idx].size);
	}

	return pdev;
}

/*
 * Registers platform devices for the regions that were reserved in earlyboot.
 *
 * This function should be called from machine initialization.
 */
void __init cma_register(void)
{
	int i;
	int id = 0;
	struct platform_device *pdev;

	for (i = 0; i < cma_data.nr_regions_valid; i++) {
		pdev = cma_register_dev_one(id, i);
		if (!pdev) {
			pr_err("couldn't register device");
			continue;
		}

		id++;
	}
}

/* CMA driver implementation */

/* Mutex for serializing accesses to private variables */
static DEFINE_SPINLOCK(cma_dev_lock);
static dev_t cma_dev_devno;
static struct class *cma_dev_class;
static struct cma_root_dev *cma_root_dev;

static int cma_dev_open(struct inode *inode, struct file *filp)
{
	dev_dbg(cma_root_dev->dev, "opened cma root device\n");
	return 0;
}

static int cma_dev_release(struct inode *inode, struct file *filp)
{
	return 0;
}

static void cma_dev_vma_open(struct vm_area_struct *vma)
{
	dev_dbg(cma_root_dev->dev, "%s: VA=0x%lx PA=0x%lx\n", __func__,
		vma->vm_start, vma->vm_pgoff << PAGE_SHIFT);
}

static void cma_dev_vma_close(struct vm_area_struct *vma)
{
	dev_dbg(cma_root_dev->dev, "%s: VA=0x%lx PA=0x%lx\n", __func__,
		vma->vm_start, vma->vm_pgoff << PAGE_SHIFT);
}

static struct vm_operations_struct cma_dev_vm_ops = {
	.open  = cma_dev_vma_open,
	.close = cma_dev_vma_close,
};

static int cma_dev_mmap(struct file *filp, struct vm_area_struct *vma)
{
	switch (cma_root_dev->mmap_type) {
	case MMAP_TYPE_NORMAL:
		break;
	case MMAP_TYPE_UNCACHED:
		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
		break;
	case MMAP_TYPE_WC:
#if defined(__arm__)
		/*
		 * ARM has an explicit setting for WC. Use default for other
		 * architectures.
		 */
		vma->vm_page_prot = __pgprot_modify(vma->vm_page_prot,
				    L_PTE_MT_MASK, L_PTE_MT_DEV_WC);
#endif
		break;
	default:
		return -EINVAL;
	}

	if (remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
			    vma->vm_end - vma->vm_start,
			    vma->vm_page_prot)) {
		return -EAGAIN;
	} else {
		vma->vm_ops = &cma_dev_vm_ops;
		cma_dev_vma_open(vma);
	}

	return 0;
}

#define NUM_BUS_RANGES 10
#define BUS_RANGE_ULIMIT_SHIFT 4
#define BUS_RANGE_LLIMIT_SHIFT 4
#define BUS_RANGE_PA_SHIFT 12

enum {
	BUSNUM_MCP0 = 0x4,
	BUSNUM_MCP1 = 0x5,
	BUSNUM_MCP2 = 0x6,
};

/*
 * If the DT nodes are handy, determine which MEMC holds the specified
 * physical address.
 */
static int phys_addr_to_memc(phys_addr_t pa)
{
	int memc = -1;
	int i;
	struct device_node *np;
	void __iomem *cpubiuctrl = NULL;
	void __iomem *curr;

	np = of_find_compatible_node(NULL, NULL, "brcm,brcmstb-cpu-biu-ctrl");
	if (!np)
		goto cleanup;

	cpubiuctrl = of_iomap(np, 0);
	if (!cpubiuctrl)
		goto cleanup;

	for (i = 0, curr = cpubiuctrl; i < NUM_BUS_RANGES; i++, curr += 8) {
		const u64 ulimit_raw = readl(curr);
		const u64 llimit_raw = readl(curr + 4);
		const u64 ulimit =
			((ulimit_raw >> BUS_RANGE_ULIMIT_SHIFT)
			 << BUS_RANGE_PA_SHIFT) | 0xfff;
		const u64 llimit = (llimit_raw >> BUS_RANGE_LLIMIT_SHIFT)
				   << BUS_RANGE_PA_SHIFT;
		const u32 busnum = (u32)(ulimit_raw & 0xf);

		if (pa >= llimit && pa <= ulimit) {
			if (busnum >= BUSNUM_MCP0 && busnum <= BUSNUM_MCP2) {
				memc = busnum - BUSNUM_MCP0;
				break;
			}
		}
	}

cleanup:
	if (cpubiuctrl)
		iounmap(cpubiuctrl);

	of_node_put(np);

	return memc;
}

/**
 * cma_dev_get_cma_dev() - Get a cma_dev * by memc index
 *
 * @memc: The MEMC index
 *
 * Return: a pointer to the associated CMA device, or NULL if no such
 * device.
 */
struct cma_dev *cma_dev_get_cma_dev(int memc)
{
	struct list_head *pos;
	struct cma_dev *cma_dev = NULL;
	unsigned long flags;

	if (!cma_root_dev)
		return NULL;

	spin_lock_irqsave(&cma_dev_lock, flags);

	list_for_each(pos, &cma_root_dev->cma_devs.list) {
		struct cma_dev *curr_cma_dev;
		curr_cma_dev = list_entry(pos, struct cma_dev, list);
		BUG_ON(curr_cma_dev == NULL);
		if (curr_cma_dev->cma_dev_index == memc) {
			cma_dev = curr_cma_dev;
			break;
		}
	}

	spin_unlock_irqrestore(&cma_dev_lock, flags);

	dev_dbg(cma_root_dev->dev, "cma_dev index %d not in list\n", memc);
	return cma_dev;
}
EXPORT_SYMBOL(cma_dev_get_cma_dev);

/**
 * cma_dev_get_mem() - Carve out physical memory
 *
 * @cma_dev: The CMA device
 * @addr: Out pointer which will be populated with the start
 * physical address of the contiguous region that was carved out
 * @len: Number of bytes to allocate
 * @align: Byte alignment
 *
 * Return: 0 on success, negative on failure.
 */
int cma_dev_get_mem(struct cma_dev *cma_dev, u64 *addr, u32 len,
			u32 align)
{
	int status = 0;
	struct page *page;
	struct device *dev = cma_dev->dev;

	if ((len & ~PAGE_MASK) || (len == 0)) {
		dev_dbg(dev, "bad length (0x%x)\n", len);
		status = -EINVAL;
		goto done;
	}

	if (align & ~PAGE_MASK) {
		dev_dbg(dev, "bad alignment (0x%x)\n", align);
		status = -EINVAL;
		goto done;
	}

	if (align <= PAGE_SIZE)
		page = dma_alloc_from_contiguous(dev, len >> PAGE_SHIFT, 0);
	else
		page = dma_alloc_from_contiguous(dev, len >> PAGE_SHIFT,
				get_order(align));

	if (page == NULL) {
		status = -ENOMEM;
		goto done;
	}

	*addr = page_to_phys(page);

done:
	return status;
}
EXPORT_SYMBOL(cma_dev_get_mem);

/**
 * cma_dev_put_mem() - Return carved out physical memory
 *
 * @cma_dev: The CMA device
 * @addr: Start physical address of allocated region
 * @len: Number of bytes that were allocated (this must match with get_mem
 * call!)
 *
 * Return: 0 on success, negative on failure.
 */
int cma_dev_put_mem(struct cma_dev *cma_dev, u64 addr, u32 len)
{
	struct page *page = phys_to_page(addr);
	struct device *dev = cma_dev->dev;

	if (page == NULL) {
		dev_dbg(cma_root_dev->dev, "bad addr (0x%llx)\n", addr);
		return -EINVAL;
	}

	if (len % PAGE_SIZE) {
		dev_dbg(cma_root_dev->dev, "bad length (0x%x)\n", len);
		return -EINVAL;
	}

	if (!dma_release_from_contiguous(dev, page, len / PAGE_SIZE))
		return -EIO;

	return 0;
}
EXPORT_SYMBOL(cma_dev_put_mem);

static int scan_alloc_bitmap(struct cma_dev *cma_dev, int op, int *region_count,
			     int region_num, s32 *memc, u64 *addr,
			     u32 *num_bytes)
{
	/* Get information about n-th contiguous chunk */
	unsigned long i = 0, pos_head = 0, pos_tail;
	int count = 0, head_found = 0;
	struct cma *cma = dev_get_cma_area(cma_dev->dev);

	if (!cma)
		return -EFAULT;

	/* Count the number of contiguous chunks */
	do {
		if (head_found) {
			pos_tail = find_next_zero_bit(cma->bitmap, cma->count,
						      i);

			if (op == GET_NUM_REGIONS)
				count++;
			else if (op == GET_REGION_INFO) {
				if (count == region_num) {
					*memc = (s32)cma_dev->memc;
					*addr = cma_dev->range.base +
						(pos_head * PAGE_SIZE);
					*num_bytes = (pos_tail - pos_head) *
						PAGE_SIZE;
					return 0;
				} else
					count++;
			}

			head_found = 0;
			i = pos_tail + 1;

		} else {
			pos_head = find_next_bit(cma->bitmap, cma->count, i);
			i = pos_head + 1;
			head_found = 1;
		}
	} while (i < cma->count);

	if (op == GET_NUM_REGIONS) {
		*region_count = count;
		return 0;
	} else
		return -EINVAL;
}

/**
 * cma_dev_get_num_regions() - Get number of allocated regions
 *
 * @cma_dev: The CMA device
 *
 * Return: 0 on success, negative on failure
 */
int cma_dev_get_num_regions(struct cma_dev *cma_dev)
{
	int count;
	int rc = scan_alloc_bitmap(cma_dev, GET_NUM_REGIONS, &count, 0, NULL,
				   NULL, NULL);
	return rc ? rc : count;
}
EXPORT_SYMBOL(cma_dev_get_num_regions);

/**
 * cma_dev_get_region_info() - Get information about allocate region
 *
 * @cma_dev: The CMA device
 * @region_num: Region index
 * @memc: MEMC index associated with the region
 * @addr: Physical address of region
 * @num_bytes: Size of region in bytes
 *
 * Return: 0 on success, negative on failure.
 */
int cma_dev_get_region_info(struct cma_dev *cma_dev, int region_num,
			    s32 *memc, u64 *addr, u32 *num_bytes)
{
	int rc = scan_alloc_bitmap(cma_dev, GET_REGION_INFO, NULL, region_num,
				   memc, addr, num_bytes);
	return rc;
}
EXPORT_SYMBOL(cma_dev_get_region_info);

static int pte_callback(pte_t *pte, unsigned long x, unsigned long y,
			struct mm_walk *walk)
{
	const pgprot_t pte_prot = __pgprot(*pte);
	const pgprot_t req_prot = *((pgprot_t *)walk->private);
	const pgprot_t prot_msk = L_PTE_MT_MASK | L_PTE_VALID;
	return (((pte_prot ^ req_prot) & prot_msk) == 0) ? 0 : -1;
}

static void *page_to_virt_contig(const struct page *page, unsigned int pg_cnt,
					pgprot_t pgprot)
{
	int rc;
	struct mm_walk walk;
	unsigned long pfn;
	unsigned long pfn_start;
	unsigned long pfn_end;
	unsigned long va_start;
	unsigned long va_end;

	if ((page == NULL) || !pg_cnt)
		return ERR_PTR(-EINVAL);

	pfn_start = page_to_pfn(page);
	pfn_end = pfn_start + pg_cnt;
	for (pfn = pfn_start; pfn < pfn_end; pfn++) {
		const struct page *cur_pg = pfn_to_page(pfn);
		phys_addr_t pa;

		/* Verify range is in low memory only */
		if (PageHighMem(cur_pg))
			return NULL;

		/* Must be mapped */
		pa = page_to_phys(cur_pg);
		if (page_address(cur_pg) == NULL)
			return NULL;
	}

	/*
	 * Aliased mappings with different cacheability attributes on ARM can
	 * lead to trouble!
	 */
	memset(&walk, 0, sizeof(walk));
	walk.pte_entry = &pte_callback;
	walk.private = (void *)&pgprot;
	walk.mm = current->mm;
	va_start = (unsigned long)page_address(page);
	va_end = (unsigned long)(page_address(page) + (pg_cnt << PAGE_SHIFT));
	rc = walk_page_range(va_start,
			     va_end,
			     &walk);
	if (rc)
		pr_debug("cacheability mismatch\n");

	return rc ? NULL : page_address(page);
}

static int cma_dev_ioctl_check_cmd(unsigned int cmd, unsigned long arg)
{
	int ret = 0;

	if (_IOC_TYPE(cmd) != CMA_DEV_MAGIC)
		return -ENOTTY;

	if (_IOC_NR(cmd) > CMA_DEV_IOC_MAXNR)
		return -ENOTTY;

	if (_IOC_DIR(cmd) & _IOC_READ)
		ret = !access_ok(VERIFY_WRITE, (void __user *)arg,
				 _IOC_SIZE(cmd));
	else if (_IOC_DIR(cmd) & _IOC_WRITE)
		ret = !access_ok(VERIFY_READ, (void __user *)arg,
				 _IOC_SIZE(cmd));

	if (ret)
		return -EFAULT;

	return 0;
}

static struct page **get_pages(struct page *page, int num_pages)
{
	struct page **pages;
	long pfn;
	int i;

	if (num_pages == 0) {
		pr_err("bad count\n");
		return NULL;
	}

	if (page == NULL) {
		pr_err("bad page\n");
		return NULL;
	}

	pages = kmalloc(sizeof(struct page *) * num_pages, GFP_KERNEL);
	if (pages == NULL)
		return NULL;

	pfn = page_to_pfn(page);
	for (i = 0; i < num_pages; i++) {
		/*
		 * pfn_to_page() should resolve to simple arithmetic for the
		 * FLATMEM memory model.
		 */
		pages[i] = pfn_to_page(pfn++);
	}

	return pages;
}

/**
 * cma_dev_kva_map() - Map page(s) to a kernel virtual address
 *
 * @page: A struct page * that points to the beginning of a chunk of physical
 * contiguous memory.
 * @num_pages: Number of pages
 * @pgprot: Page protection bits
 *
 * Return: pointer to mapping, or NULL on failure
 */
void *cma_dev_kva_map(struct page *page, int num_pages, pgprot_t pgprot)
{
	void *va;

	/* get the virtual address for this range if it exists */
	va = page_to_virt_contig(page, num_pages, pgprot);
	if (IS_ERR(va)) {
		pr_debug("page_to_virt_contig() failed (%ld)\n", PTR_ERR(va));
		return NULL;
	} else if (va == NULL || is_vmalloc_addr(va)) {
		struct page **pages;

		pages = get_pages(page, num_pages);
		if (pages == NULL) {
			pr_err("couldn't get pages\n");
			return NULL;
		}

		va = vmap(pages, num_pages, 0, pgprot);

		kfree(pages);

		if (va == NULL) {
			pr_err("vmap failed (num_pgs=%d)\n", num_pages);
			return NULL;
		}
	}

	return va;
}
EXPORT_SYMBOL(cma_dev_kva_map);

/**
 * cma_dev_kva_unmap() - Unmap a kernel virtual address associated
 * to physical pages mapped by cma_dev_kva_map()
 *
 * @kva: Kernel virtual address previously mapped by cma_dev_kva_map()
 *
 * Return: 0 on success, negative on failure.
 */
int cma_dev_kva_unmap(const void *kva)
{
	if (kva == NULL)
		return -EINVAL;

	if (!is_vmalloc_addr(kva)) {
		/* unmapping not necessary for low memory VAs */
		return 0;
	}

	vunmap(kva);

	return 0;
}
EXPORT_SYMBOL(cma_dev_kva_unmap);

static long cma_dev_ioctl(struct file *filp, unsigned int cmd,
			  unsigned long arg)
{
	int ret = 0;
	struct device *dev = cma_root_dev->dev;
	struct cma_dev *cma_dev;
	struct ioc_params p;

	ret = cma_dev_ioctl_check_cmd(cmd, arg);
	if (ret)
		return ret;

	if (cmd < CMA_DEV_IOC_GET_PG_PROT) {
		if (copy_from_user(&p, (void __user *)(arg), sizeof(p)))
			return -EFAULT;
	}

	switch (cmd) {
	case CMA_DEV_IOC_GETMEM: {
		ret = -EINVAL;

		cma_dev = cma_dev_get_cma_dev(p.cma_dev_index);
		if (cma_dev == NULL)
			break;

		p.status = cma_dev_get_mem(cma_dev, &p.addr, p.num_bytes,
						p.align_bytes);

		ret = 0;

		break;
	}
	case CMA_DEV_IOC_PUTMEM: {
		ret = -EINVAL;

		cma_dev = cma_dev_get_cma_dev(p.cma_dev_index);
		if (cma_dev == NULL)
			break;

		p.status = cma_dev_put_mem(cma_dev, p.addr, p.num_bytes);

		ret = 0;

		break;
	}
	case CMA_DEV_IOC_GETPHYSINFO: {
		ret = -EINVAL;

		cma_dev = cma_dev_get_cma_dev(p.cma_dev_index);
		if (cma_dev == NULL)
			break;

		p.addr = cma_dev->range.base;
		p.num_bytes = cma_dev->range.size;
		p.memc = (s32)cma_dev->memc;
		p.status = 0;

		ret = 0;

		break;
	}
	case CMA_DEV_IOC_GETNUMREGS: {
		ret = -EINVAL;

		cma_dev = cma_dev_get_cma_dev(p.cma_dev_index);
		if (cma_dev == NULL)
			break;

		p.num_regions = cma_dev_get_num_regions(cma_dev);

		ret = 0;

		break;
	}
	case CMA_DEV_IOC_GETREGINFO: {
		ret = -EINVAL;

		cma_dev = cma_dev_get_cma_dev(p.cma_dev_index);
		if (cma_dev == NULL)
			break;

		p.status = cma_dev_get_region_info(cma_dev, p.region, &p.memc,
							&p.addr, &p.num_bytes);

		ret = 0;

		break;
	}
	case CMA_DEV_IOC_GET_PG_PROT: {
		__put_user(cma_root_dev->mmap_type, (u32 __user *)arg);
		break;
	}
	case CMA_DEV_IOC_SET_PG_PROT: {
		int mmap_type;

		__get_user(mmap_type, (u32 __user *)arg);

		if (mmap_type > MMAP_TYPE_WC) {
			dev_err(dev, "bad mmap_type (%d)\n", mmap_type);
			ret = -EINVAL;
		} else
			cma_root_dev->mmap_type = mmap_type;

		break;
	}
	case CMA_DEV_IOC_VERSION: {
		__put_user(CMA_DRIVER_VERSION, (__u32 __user *)arg);
		break;
	}
	default: {
		return -ENOTTY;
	}
	}

	if (cmd < CMA_DEV_IOC_GET_PG_PROT) {
		if (copy_to_user((void __user *)(arg), &p, sizeof(p)))
			return -EFAULT;
	}

	return ret;
}

static const struct file_operations cma_dev_fops = {
	.owner          = THIS_MODULE,
	.open           = cma_dev_open,
	.release        = cma_dev_release,
	.mmap           = cma_dev_mmap,
	.unlocked_ioctl = cma_dev_ioctl,
};

static int cma_drvr_alloc_devno(struct device *dev)
{
	int ret = 0;

	if (MAJOR(cma_dev_devno) == 0) {
		ret = alloc_chrdev_region(&cma_dev_devno, 0, CMA_DEV_MAX,
					  CMA_DEV_NAME);
	}

	if (ret) {
		dev_err(dev, "couldn't alloc major devno\n");
		return ret;
	}

	dev_dbg(dev, "maj=%d min=%d\n", MAJOR(cma_dev_devno),
	MINOR(cma_dev_devno));

	return ret;
}

static int cma_drvr_test_cma_dev(struct device *dev)
{
	struct page *page;

	/* Do a dummy alloc to ensure the CMA device is truly ready */
	page = dma_alloc_from_contiguous(dev, 1, 0);
	if (page == NULL)
		return -EINVAL;

	if (!dma_release_from_contiguous(dev, page, 1)) {
		dev_err(dev, "test dma release failed!\n");
		return -EINVAL;
	}

	return 0;
}

static int __init cma_drvr_config_platdev(struct platform_device *pdev,
					struct cma_dev *cma_dev)
{
	struct device *dev = &pdev->dev;
	struct cma_pdev_data *data =
		(struct cma_pdev_data *)dev->platform_data;

	if (!data) {
		dev_err(dev, "platform data not initialized\n");
		return -EINVAL;
	}

	cma_dev->range.base = data->start;
	cma_dev->range.size = data->size;
	cma_dev->cma_dev_index = pdev->id;
	cma_dev->memc = phys_addr_to_memc(data->start);

	if (!data->cma_area) {
		pr_err("null cma area\n");
		return -EINVAL;
	}
	dev_set_cma_area(dev, data->cma_area);

	if (cma_drvr_test_cma_dev(dev)) {
		dev_err(dev, "CMA testing failed!\n");
		return -EINVAL;
	}

	return 0;
}

static int cma_drvr_init_root_dev(struct device *dev)
{
	int ret;
	struct device *dev2;
	struct cma_root_dev *my_cma_root_dev;
	struct cdev *cdev;
	int minor = 0;

	my_cma_root_dev = devm_kzalloc(dev, sizeof(*my_cma_root_dev),
					GFP_KERNEL);
	if (my_cma_root_dev == NULL)
		return -ENOMEM;

	/* Initialize list of CMA devices referenced by the root CMA device */
	INIT_LIST_HEAD(&my_cma_root_dev->cma_devs.list);

	/* Setup character device */
	cdev = &my_cma_root_dev->cdev;
	cdev_init(cdev, &cma_dev_fops);
	cdev->owner = THIS_MODULE;
	ret = cdev_add(cdev, cma_dev_devno + minor, 1);
	if (ret) {
		dev_err(dev, "cdev_add() failed (%d)\n", ret);
		goto free_cma_root_dev;
	}

	if (cma_dev_class == NULL)
		cma_dev_class = class_create(THIS_MODULE, CMA_CLASS_NAME);

	/* Setup device */
	dev2 = device_create(cma_dev_class, dev, cma_dev_devno + minor, NULL,
			     CMA_DEV_NAME"%d", minor);
	if (IS_ERR(dev2)) {
		dev_err(dev, "error creating device (%d)\n", ret);
		ret = PTR_ERR(dev2);
		goto del_cdev;
	}

	my_cma_root_dev->dev = dev2;
	cma_root_dev = my_cma_root_dev;

	dev_info(dev, "Initialized Broadcom CMA root device\n");

	goto done;

del_cdev:
	cdev_del(cdev);

free_cma_root_dev:
	devm_kfree(dev, cma_root_dev);

done:
	return ret;
}

static int __init cma_drvr_do_prealloc(struct device *dev,
	struct cma_dev *cma_dev)
{
	int ret;
	u64 addr;
	u32 size;

	size = cma_dev->range.size;
#ifdef CONFIG_BRCMSTB_USE_MEGA_BARRIER
	/* Every CMA device needs to accomodate the mega-barrier page if a
	 * pre-allocation is needed.
	 */
	if (size > PAGE_SIZE)
		size -= PAGE_SIZE;
#endif

	ret = cma_dev_get_mem(cma_dev, &addr, size, 0);
	if (ret)
		dev_err(dev, "Unable to pre-allocate 0x%x bytes (%d)", size,
			ret);
	else
		dev_info(dev, "Pre-allocated 0x%x bytes @ 0x%llx", size, addr);

	return ret;
}

static int __init cma_drvr_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct cma_dev *cma_dev = NULL;
	int ret = 0;
	struct cma_pdev_data *data =
		(struct cma_pdev_data *)dev->platform_data;

	/* Prepare a major number for the devices if not already done */
	ret = cma_drvr_alloc_devno(dev);
	if (ret)
		goto free_cma_dev;

	/* Initialize the root device only once */
	if (cma_root_dev == NULL)
		ret = cma_drvr_init_root_dev(dev);

	if (ret)
		goto done;

	cma_dev = devm_kzalloc(dev, sizeof(*cma_dev), GFP_KERNEL);
	if (cma_dev == NULL) {
		dev_err(dev, "can't alloc cma_dev\n");
		ret = -ENOMEM;
		goto done;
	}

	ret = cma_drvr_config_platdev(pdev, cma_dev);
	if (ret)
		goto free_cma_dev;

	cma_dev->dev = dev;

	/*
	 * Keep a pointer to all of the devs so we don't have to search for it
	 * elsewhere.
	 */
	INIT_LIST_HEAD(&cma_dev->list);
	list_add(&cma_dev->list, &cma_root_dev->cma_devs.list);
	dev_info(dev, "Added CMA device @ PA=0x%llx LEN=0x%x\n",
		 cma_dev->range.base, cma_dev->range.size);

	if (data->do_prealloc) {
		/*
		 * Pre-allocation failure isn't truly a probe error because the
		 * device has been initialized at this point. An error will be
		 * logged if there is a failure.
		 */
		cma_drvr_do_prealloc(dev, cma_dev);
	}

	goto done;

free_cma_dev:
	devm_kfree(dev, cma_dev);

done:
	return ret;
}

int cma_drvr_is_ready(void)
{
	return cma_root_dev != NULL;
}

static struct platform_driver cma_driver = {
	.driver = {
		.name = "brcm-cma",
		.owner = THIS_MODULE,
	},
};

static int __init cma_drvr_init(void)
{
	return platform_driver_probe(&cma_driver, cma_drvr_probe);
}
module_init(cma_drvr_init);

static void __exit cma_drvr_exit(void)
{
	platform_driver_unregister(&cma_driver);
}
module_exit(cma_drvr_exit);