aboutsummaryrefslogtreecommitdiff
path: root/drivers/usb/core/buffer.c
blob: b0585e623ba9ac38a161405b7f1c346ea063f044 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
/*
 * DMA memory management for framework level HCD code (hc_driver)
 *
 * This implementation plugs in through generic "usb_bus" level methods,
 * and should work with all USB controllers, regardles of bus type.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/mm.h>
#include <linux/io.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/usb.h>
#include <linux/usb/hcd.h>


/*
 * DMA-Coherent Buffers
 */

/* FIXME tune these based on pool statistics ... */
static const size_t	pool_max[HCD_BUFFER_POOLS] = {
	/* platforms without dma-friendly caches might need to
	 * prevent cacheline sharing...
	 */
	32,
	128,
	512,
	PAGE_SIZE / 2
	/* bigger --> allocate pages */
};


/* SETUP primitives */

/**
 * hcd_buffer_create - initialize buffer pools
 * @hcd: the bus whose buffer pools are to be initialized
 * Context: !in_interrupt()
 *
 * Call this as part of initializing a host controller that uses the dma
 * memory allocators.  It initializes some pools of dma-coherent memory that
 * will be shared by all drivers using that controller, or returns a negative
 * errno value on error.
 *
 * Call hcd_buffer_destroy() to clean up after using those pools.
 */
int hcd_buffer_create(struct usb_hcd *hcd)
{
	char		name[16];
	int		i, size;

	if (!hcd->self.controller->dma_mask &&
	    !(hcd->driver->flags & HCD_LOCAL_MEM))
		return 0;

	for (i = 0; i < HCD_BUFFER_POOLS; i++) {
		size = pool_max[i];
		if (!size)
			continue;
		snprintf(name, sizeof name, "buffer-%d", size);
		hcd->pool[i] = dma_pool_create(name, hcd->self.controller,
				size, size, 0);
		if (!hcd->pool[i]) {
			hcd_buffer_destroy(hcd);
			return -ENOMEM;
		}
	}
	return 0;
}


/**
 * hcd_buffer_destroy - deallocate buffer pools
 * @hcd: the bus whose buffer pools are to be destroyed
 * Context: !in_interrupt()
 *
 * This frees the buffer pools created by hcd_buffer_create().
 */
void hcd_buffer_destroy(struct usb_hcd *hcd)
{
	int i;

	for (i = 0; i < HCD_BUFFER_POOLS; i++) {
		struct dma_pool *pool = hcd->pool[i];
		if (pool) {
			dma_pool_destroy(pool);
			hcd->pool[i] = NULL;
		}
	}
}


/* sometimes alloc/free could use kmalloc with GFP_DMA, for
 * better sharing and to leverage mm/slab.c intelligence.
 */

void *hcd_buffer_alloc(
	struct usb_bus		*bus,
	size_t			size,
	gfp_t			mem_flags,
	dma_addr_t		*dma
)
{
	struct usb_hcd		*hcd = bus_to_hcd(bus);
	int			i;

	/* some USB hosts just use PIO */
	if (!bus->controller->dma_mask &&
	    !(hcd->driver->flags & HCD_LOCAL_MEM)) {
		*dma = ~(dma_addr_t) 0;
		return kmalloc(size, mem_flags);
	}

	for (i = 0; i < HCD_BUFFER_POOLS; i++) {
		if (size <= pool_max[i])
			return dma_pool_alloc(hcd->pool[i], mem_flags, dma);
	}
	return dma_alloc_coherent(hcd->self.controller, size, dma, mem_flags);
}

void hcd_buffer_free(
	struct usb_bus		*bus,
	size_t			size,
	void			*addr,
	dma_addr_t		dma
)
{
	struct usb_hcd		*hcd = bus_to_hcd(bus);
	int			i;

	if (!addr)
		return;

	if (!bus->controller->dma_mask &&
	    !(hcd->driver->flags & HCD_LOCAL_MEM)) {
		kfree(addr);
		return;
	}

	for (i = 0; i < HCD_BUFFER_POOLS; i++) {
		if (size <= pool_max[i]) {
			dma_pool_free(hcd->pool[i], addr, dma);
			return;
		}
	}
	dma_free_coherent(hcd->self.controller, size, addr, dma);
}