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Subject[PATCH v2 2/2] drivers: dma-coherent: show per-device DMA region utilization via procfs
Date
From: "George G. Davis" <george_davis@mentor.com>

Add hooks to allow displaying per-device DMA region utilization via
/proc/dmainfo similar to how free blocks are displayed in
/proc/pagetypeinfo.

This also adds /proc/dmainfo reporting for regions defined via
dma_declare_coherent_memory().

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: George G. Davis <george_davis@mentor.com>
Signed-off-by: Mark Craske <Mark_Craske@mentor.com>
Signed-off-by: Vitaly Kuzmichev <vitaly_kuzmichev@mentor.com>
---
drivers/base/dma-coherent.c | 224 ++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 215 insertions(+), 9 deletions(-)

diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
index acfe140..2692e6d 100644
--- a/drivers/base/dma-coherent.c
+++ b/drivers/base/dma-coherent.c
@@ -8,6 +8,12 @@
#include <linux/module.h>
#include <linux/dma-mapping.h>

+#ifdef CONFIG_PROC_FS
+#include <linux/fs.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#endif
+
struct dma_coherent_mem {
void *virt_base;
dma_addr_t device_base;
@@ -17,8 +23,57 @@ struct dma_coherent_mem {
unsigned long *bitmap;
spinlock_t spinlock;
bool use_dev_dma_pfn_offset;
+ int used;
+ int highwatermark;
+ int errs;
};

+#ifdef CONFIG_PROC_FS
+struct dmacoherent_region {
+ struct list_head list;
+ struct device *dev;
+};
+
+static LIST_HEAD(dmacoherent_region_list);
+static DEFINE_MUTEX(dmacoherent_region_list_lock);
+
+static int dmacoherent_region_add(struct device *dev)
+{
+ struct dmacoherent_region *rp;
+
+ rp = kzalloc(sizeof(*rp), GFP_KERNEL);
+ if (!rp)
+ return -ENOMEM;
+
+ rp->dev = dev;
+
+ mutex_lock(&dmacoherent_region_list_lock);
+ list_add(&rp->list, &dmacoherent_region_list);
+ mutex_unlock(&dmacoherent_region_list_lock);
+ dev_info(dev, "Registered DMA-coherent pool with /proc/dmainfo accounting\n");
+
+ return 0;
+}
+
+static void dmacoherent_region_del(struct device *dev)
+{
+ struct dmacoherent_region *rp;
+
+ mutex_lock(&dmacoherent_region_list_lock);
+ list_for_each_entry(rp, &dmacoherent_region_list, list) {
+ if (rp->dev == dev) {
+ list_del(&rp->list);
+ kfree(rp);
+ break;
+ }
+ }
+ mutex_unlock(&dmacoherent_region_list_lock);
+}
+#else
+static int dmacoherent_region_add(struct device *dev) { return 0; }
+static void dmacoherent_region_del(struct device *dev) { return; }
+#endif
+
static struct dma_coherent_mem *dma_coherent_default_memory __ro_after_init;

static inline struct dma_coherent_mem *dev_get_coherent_memory(struct device *dev)
@@ -122,14 +177,22 @@ int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
dma_addr_t device_addr, size_t size, int flags)
{
struct dma_coherent_mem *mem;
+ int ret;

if (!dma_init_coherent_memory(phys_addr, device_addr, size, flags,
&mem))
return 0;

- if (dma_assign_coherent_memory(dev, mem) == 0)
- return flags & DMA_MEMORY_MAP ? DMA_MEMORY_MAP : DMA_MEMORY_IO;
+ if (dma_assign_coherent_memory(dev, mem) != 0)
+ goto errout;
+
+ ret = (flags & DMA_MEMORY_MAP ? DMA_MEMORY_MAP : DMA_MEMORY_IO);

+ if (dmacoherent_region_add(dev) == 0)
+ return ret;
+
+ dev->dma_mem = NULL;
+errout:
dma_release_coherent_memory(mem);
return 0;
}
@@ -141,6 +204,8 @@ void dma_release_declared_memory(struct device *dev)

if (!mem)
return;
+
+ dmacoherent_region_del(dev);
dma_release_coherent_memory(mem);
dev->dma_mem = NULL;
}
@@ -152,19 +217,25 @@ void *dma_mark_declared_memory_occupied(struct device *dev,
struct dma_coherent_mem *mem = dev->dma_mem;
unsigned long flags;
int pos, err;
-
- size += device_addr & ~PAGE_MASK;
+ int order;

if (!mem)
return ERR_PTR(-EINVAL);

- spin_lock_irqsave(&mem->spinlock, flags);
+ size += device_addr & ~PAGE_MASK;
+ order = get_order(size);
pos = PFN_DOWN(device_addr - dma_get_device_base(dev, mem));
- err = bitmap_allocate_region(mem->bitmap, pos, get_order(size));
- spin_unlock_irqrestore(&mem->spinlock, flags);

- if (err != 0)
+ spin_lock_irqsave(&mem->spinlock, flags);
+ err = bitmap_allocate_region(mem->bitmap, pos, order);
+ if (err != 0) {
+ spin_unlock_irqrestore(&mem->spinlock, flags);
return ERR_PTR(err);
+ }
+ mem->used += 1 << order;
+ if (mem->highwatermark < mem->used)
+ mem->highwatermark = mem->used;
+ spin_unlock_irqrestore(&mem->spinlock, flags);
return mem->virt_base + (pos << PAGE_SHIFT);
}
EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
@@ -206,6 +277,10 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size,
if (unlikely(pageno < 0))
goto err;

+ mem->used += 1 << order;
+ if (mem->highwatermark < mem->used)
+ mem->highwatermark = mem->used;
+
/*
* Memory was found in the per-device area.
*/
@@ -221,6 +296,7 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size,
return 1;

err:
+ mem->errs++;
spin_unlock_irqrestore(&mem->spinlock, flags);
/*
* In the case where the allocation can not be satisfied from the
@@ -255,6 +331,7 @@ int dma_release_from_coherent(struct device *dev, int order, void *vaddr)

spin_lock_irqsave(&mem->spinlock, flags);
bitmap_release_region(mem->bitmap, page, order);
+ mem->used -= 1 << order;
spin_unlock_irqrestore(&mem->spinlock, flags);
return 1;
}
@@ -326,6 +403,10 @@ static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
}
mem->use_dev_dma_pfn_offset = true;
rmem->priv = mem;
+
+ if (dmacoherent_region_add(dev))
+ return -ENOMEM;
+
dma_assign_coherent_memory(dev, mem);
return 0;
}
@@ -333,8 +414,10 @@ static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
static void rmem_dma_device_release(struct reserved_mem *rmem,
struct device *dev)
{
- if (dev)
+ if (dev) {
+ dmacoherent_region_del(dev);
dev->dma_mem = NULL;
+ }
}

static const struct reserved_mem_ops rmem_dma_ops = {
@@ -396,3 +479,126 @@ static int __init dma_init_reserved_memory(void)

RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup);
#endif
+
+#ifdef CONFIG_PROC_FS
+
+static int dmainfo_proc_show_dma_mem(struct seq_file *m, void *v,
+ struct device *dev)
+{
+ struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
+ int offset;
+ int start;
+ int end;
+ int pages;
+ int order;
+ int free = 0;
+ int blocks[MAX_ORDER];
+
+ memset(blocks, 0, sizeof(blocks));
+
+ spin_lock(&mem->spinlock);
+
+ for (offset = 0; offset < mem->size; offset = end) {
+ start = find_next_zero_bit(mem->bitmap, mem->size, offset);
+ if (start >= mem->size)
+ break;
+ end = find_next_bit(mem->bitmap, mem->size, start + 1);
+ pages = end - start;
+
+ /* Align start: */
+ for (order = 0; order < MAX_ORDER; order += 1) {
+ if (start >= end)
+ break;
+ if (pages < (1 << order))
+ break;
+ if (start & (1 << order)) {
+ blocks[order] += 1;
+ start += 1 << order;
+ pages -= 1 << order;
+ free += 1 << order;
+ }
+ }
+
+ if (start >= end)
+ continue;
+
+ /* Align middle and end: */
+ order = MAX_ORDER - 1;
+ while (order >= 0) {
+ if (start >= end)
+ break;
+ if (pages >= (1 << order)) {
+ blocks[order] += 1;
+ start += 1 << order;
+ pages -= 1 << order;
+ free += 1 << order;
+ } else {
+ order -= 1;
+ }
+ }
+ }
+
+ seq_printf(m, "%-30s", dev_name(dev));
+
+ for (order = 0; order < MAX_ORDER; order += 1)
+ seq_printf(m, " %6d", blocks[order]);
+
+ seq_printf(m, " %6d %6d %6d %6d %6d\n",
+ mem->size,
+ mem->used,
+ free,
+ mem->highwatermark,
+ mem->errs);
+
+ spin_unlock(&mem->spinlock);
+
+ return 0;
+}
+
+static int dmainfo_proc_show(struct seq_file *m, void *v)
+{
+ struct dmacoherent_region *rp;
+ int order;
+
+ seq_puts(m, "DMA-coherent region information:\n");
+ seq_printf(m, "%-30s", "Free block count at order");
+
+ for (order = 0; order < MAX_ORDER; ++order)
+ seq_printf(m, " %6d", order);
+
+ seq_printf(m, " %6s %6s %6s %6s %6s\n",
+ "Size",
+ "Used",
+ "Free",
+ "High",
+ "Errs");
+
+ mutex_lock(&dmacoherent_region_list_lock);
+ list_for_each_entry(rp, &dmacoherent_region_list, list) {
+ dmainfo_proc_show_dma_mem(m, v, rp->dev);
+ }
+ mutex_unlock(&dmacoherent_region_list_lock);
+
+ return 0;
+}
+
+static int dmainfo_proc_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, dmainfo_proc_show, NULL);
+}
+
+static const struct file_operations dmainfo_proc_fops = {
+ .open = dmainfo_proc_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int __init proc_dmainfo_init(void)
+{
+ proc_create("dmainfo", 0, NULL, &dmainfo_proc_fops);
+ return 0;
+}
+module_init(proc_dmainfo_init);
+
+#endif
--
1.9.1
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