1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * DMA memory management for framework level HCD code (hc_driver)
4  *
5  * This implementation plugs in through generic "usb_bus" level methods,
6  * and should work with all USB controllers, regardless of bus type.
7  *
8  * Released under the GPLv2 only.
9  */
10 
11 #include <linux/module.h>
12 #include <linux/kernel.h>
13 #include <linux/slab.h>
14 #include <linux/device.h>
15 #include <linux/mm.h>
16 #include <linux/io.h>
17 #include <linux/dma-mapping.h>
18 #include <linux/dmapool.h>
19 #include <linux/genalloc.h>
20 #include <linux/usb.h>
21 #include <linux/usb/hcd.h>
22 
23 
24 /*
25  * DMA-Coherent Buffers
26  */
27 
28 /* FIXME tune these based on pool statistics ... */
29 static size_t pool_max[HCD_BUFFER_POOLS] = {
30 	32, 128, 512, 2048,
31 };
32 
usb_init_pool_max(void)33 void __init usb_init_pool_max(void)
34 {
35 	/*
36 	 * The pool_max values must never be smaller than
37 	 * ARCH_KMALLOC_MINALIGN.
38 	 */
39 	if (ARCH_KMALLOC_MINALIGN <= 32)
40 		;			/* Original value is okay */
41 	else if (ARCH_KMALLOC_MINALIGN <= 64)
42 		pool_max[0] = 64;
43 	else if (ARCH_KMALLOC_MINALIGN <= 128)
44 		pool_max[0] = 0;	/* Don't use this pool */
45 	else
46 		BUILD_BUG();		/* We don't allow this */
47 }
48 
49 /* SETUP primitives */
50 
51 /**
52  * hcd_buffer_create - initialize buffer pools
53  * @hcd: the bus whose buffer pools are to be initialized
54  *
55  * Context: task context, might sleep
56  *
57  * Call this as part of initializing a host controller that uses the dma
58  * memory allocators.  It initializes some pools of dma-coherent memory that
59  * will be shared by all drivers using that controller.
60  *
61  * Call hcd_buffer_destroy() to clean up after using those pools.
62  *
63  * Return: 0 if successful. A negative errno value otherwise.
64  */
hcd_buffer_create(struct usb_hcd * hcd)65 int hcd_buffer_create(struct usb_hcd *hcd)
66 {
67 	char		name[16];
68 	int		i, size;
69 
70 	if (hcd->localmem_pool || !hcd_uses_dma(hcd))
71 		return 0;
72 
73 	for (i = 0; i < HCD_BUFFER_POOLS; i++) {
74 		size = pool_max[i];
75 		if (!size)
76 			continue;
77 		snprintf(name, sizeof(name), "buffer-%d", size);
78 		hcd->pool[i] = dma_pool_create(name, hcd->self.sysdev,
79 				size, size, 0);
80 		if (!hcd->pool[i]) {
81 			hcd_buffer_destroy(hcd);
82 			return -ENOMEM;
83 		}
84 	}
85 	return 0;
86 }
87 
88 
89 /**
90  * hcd_buffer_destroy - deallocate buffer pools
91  * @hcd: the bus whose buffer pools are to be destroyed
92  *
93  * Context: task context, might sleep
94  *
95  * This frees the buffer pools created by hcd_buffer_create().
96  */
hcd_buffer_destroy(struct usb_hcd * hcd)97 void hcd_buffer_destroy(struct usb_hcd *hcd)
98 {
99 	int i;
100 
101 	if (!IS_ENABLED(CONFIG_HAS_DMA))
102 		return;
103 
104 	for (i = 0; i < HCD_BUFFER_POOLS; i++) {
105 		dma_pool_destroy(hcd->pool[i]);
106 		hcd->pool[i] = NULL;
107 	}
108 }
109 
110 
111 /* sometimes alloc/free could use kmalloc with GFP_DMA, for
112  * better sharing and to leverage mm/slab.c intelligence.
113  */
114 
hcd_buffer_alloc(struct usb_bus * bus,size_t size,gfp_t mem_flags,dma_addr_t * dma)115 void *hcd_buffer_alloc(
116 	struct usb_bus		*bus,
117 	size_t			size,
118 	gfp_t			mem_flags,
119 	dma_addr_t		*dma
120 )
121 {
122 	struct usb_hcd		*hcd = bus_to_hcd(bus);
123 	int			i;
124 
125 	if (size == 0)
126 		return NULL;
127 
128 	if (hcd->localmem_pool)
129 		return gen_pool_dma_alloc(hcd->localmem_pool, size, dma);
130 
131 	/* some USB hosts just use PIO */
132 	if (!hcd_uses_dma(hcd)) {
133 		*dma = ~(dma_addr_t) 0;
134 		return kmalloc(size, mem_flags);
135 	}
136 
137 	for (i = 0; i < HCD_BUFFER_POOLS; i++) {
138 		if (size <= pool_max[i])
139 			return dma_pool_alloc(hcd->pool[i], mem_flags, dma);
140 	}
141 	return dma_alloc_coherent(hcd->self.sysdev, size, dma, mem_flags);
142 }
143 
hcd_buffer_free(struct usb_bus * bus,size_t size,void * addr,dma_addr_t dma)144 void hcd_buffer_free(
145 	struct usb_bus		*bus,
146 	size_t			size,
147 	void			*addr,
148 	dma_addr_t		dma
149 )
150 {
151 	struct usb_hcd		*hcd = bus_to_hcd(bus);
152 	int			i;
153 
154 	if (!addr)
155 		return;
156 
157 	if (hcd->localmem_pool) {
158 		gen_pool_free(hcd->localmem_pool, (unsigned long)addr, size);
159 		return;
160 	}
161 
162 	if (!hcd_uses_dma(hcd)) {
163 		kfree(addr);
164 		return;
165 	}
166 
167 	for (i = 0; i < HCD_BUFFER_POOLS; i++) {
168 		if (size <= pool_max[i]) {
169 			dma_pool_free(hcd->pool[i], addr, dma);
170 			return;
171 		}
172 	}
173 	dma_free_coherent(hcd->self.sysdev, size, addr, dma);
174 }
175