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
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
|
From 9d449a908099a6dc0779bb1a9e87f5e224909a24 Mon Sep 17 00:00:00 2001
From: Martin Sperl <kernel@martin.sperl.org>
Date: Wed, 16 Mar 2016 12:25:01 -0700
Subject: [PATCH] dmaengine: bcm2835: add slave_sg support to bcm2835-dma
Add slave_sg support to bcm2835-dma using shared allocation
code for bcm2835_desc and DMA-control blocks already used by
dma_cyclic.
Note that bcm2835_dma_callback had to get modified to support
both modes of operation (cyclic and non-cyclic).
Tested using:
* Hifiberry I2S card (using cyclic DMA)
* fb_st7735r SPI-framebuffer (using slave_sg DMA via spi-bcm2835)
playing BigBuckBunny for audio and video.
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
---
drivers/dma/bcm2835-dma.c | 113 ++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 108 insertions(+), 5 deletions(-)
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -260,6 +260,23 @@ static void bcm2835_dma_create_cb_set_le
control_block->info |= finalextrainfo;
}
+static inline size_t bcm2835_dma_count_frames_for_sg(
+ struct bcm2835_chan *c,
+ struct scatterlist *sgl,
+ unsigned int sg_len)
+{
+ size_t frames = 0;
+ struct scatterlist *sgent;
+ unsigned int i;
+ size_t plength = bcm2835_dma_max_frame_length(c);
+
+ for_each_sg(sgl, sgent, sg_len, i)
+ frames += bcm2835_dma_frames_for_length(
+ sg_dma_len(sgent), plength);
+
+ return frames;
+}
+
/**
* bcm2835_dma_create_cb_chain - create a control block and fills data in
*
@@ -361,6 +378,32 @@ error_cb:
return NULL;
}
+static void bcm2835_dma_fill_cb_chain_with_sg(
+ struct dma_chan *chan,
+ enum dma_transfer_direction direction,
+ struct bcm2835_cb_entry *cb,
+ struct scatterlist *sgl,
+ unsigned int sg_len)
+{
+ struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
+ size_t max_len = bcm2835_dma_max_frame_length(c);
+ unsigned int i, len;
+ dma_addr_t addr;
+ struct scatterlist *sgent;
+
+ for_each_sg(sgl, sgent, sg_len, i) {
+ for (addr = sg_dma_address(sgent), len = sg_dma_len(sgent);
+ len > 0;
+ addr += cb->cb->length, len -= cb->cb->length, cb++) {
+ if (direction == DMA_DEV_TO_MEM)
+ cb->cb->dst = addr;
+ else
+ cb->cb->src = addr;
+ cb->cb->length = min(len, max_len);
+ }
+ }
+}
+
static int bcm2835_dma_abort(void __iomem *chan_base)
{
unsigned long cs;
@@ -428,13 +471,19 @@ static irqreturn_t bcm2835_dma_callback(
d = c->desc;
if (d) {
- /* TODO Only works for cyclic DMA */
- vchan_cyclic_callback(&d->vd);
+ if (d->cyclic) {
+ /* call the cyclic callback */
+ vchan_cyclic_callback(&d->vd);
+
+ /* Keep the DMA engine running */
+ writel(BCM2835_DMA_ACTIVE,
+ c->chan_base + BCM2835_DMA_CS);
+ } else {
+ vchan_cookie_complete(&c->desc->vd);
+ bcm2835_dma_start_desc(c);
+ }
}
- /* Keep the DMA engine running */
- writel(BCM2835_DMA_ACTIVE, c->chan_base + BCM2835_DMA_CS);
-
spin_unlock_irqrestore(&c->vc.lock, flags);
return IRQ_HANDLED;
@@ -548,6 +597,58 @@ static void bcm2835_dma_issue_pending(st
spin_unlock_irqrestore(&c->vc.lock, flags);
}
+static struct dma_async_tx_descriptor *bcm2835_dma_prep_slave_sg(
+ struct dma_chan *chan,
+ struct scatterlist *sgl, unsigned int sg_len,
+ enum dma_transfer_direction direction,
+ unsigned long flags, void *context)
+{
+ struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
+ struct bcm2835_desc *d;
+ dma_addr_t src = 0, dst = 0;
+ u32 info = BCM2835_DMA_WAIT_RESP;
+ u32 extra = BCM2835_DMA_INT_EN;
+ size_t frames;
+
+ if (!is_slave_direction(direction)) {
+ dev_err(chan->device->dev,
+ "%s: bad direction?\n", __func__);
+ return NULL;
+ }
+
+ if (c->dreq != 0)
+ info |= BCM2835_DMA_PER_MAP(c->dreq);
+
+ if (direction == DMA_DEV_TO_MEM) {
+ if (c->cfg.src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
+ return NULL;
+ src = c->cfg.src_addr;
+ info |= BCM2835_DMA_S_DREQ | BCM2835_DMA_D_INC;
+ } else {
+ if (c->cfg.dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
+ return NULL;
+ dst = c->cfg.dst_addr;
+ info |= BCM2835_DMA_D_DREQ | BCM2835_DMA_S_INC;
+ }
+
+ /* count frames in sg list */
+ frames = bcm2835_dma_count_frames_for_sg(c, sgl, sg_len);
+
+ /* allocate the CB chain */
+ d = bcm2835_dma_create_cb_chain(chan, direction, false,
+ info, extra,
+ frames, src, dst, 0, 0,
+ GFP_KERNEL);
+ if (!d)
+ return NULL;
+
+ /* fill in frames with scatterlist pointers */
+ bcm2835_dma_fill_cb_chain_with_sg(chan, direction, d->cb_list,
+ sgl, sg_len);
+
+ return vchan_tx_prep(&c->vc, &d->vd, flags);
+}
+
static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
size_t period_len, enum dma_transfer_direction direction,
@@ -778,11 +879,13 @@ static int bcm2835_dma_probe(struct plat
dma_cap_set(DMA_SLAVE, od->ddev.cap_mask);
dma_cap_set(DMA_PRIVATE, od->ddev.cap_mask);
dma_cap_set(DMA_CYCLIC, od->ddev.cap_mask);
+ dma_cap_set(DMA_SLAVE, od->ddev.cap_mask);
od->ddev.device_alloc_chan_resources = bcm2835_dma_alloc_chan_resources;
od->ddev.device_free_chan_resources = bcm2835_dma_free_chan_resources;
od->ddev.device_tx_status = bcm2835_dma_tx_status;
od->ddev.device_issue_pending = bcm2835_dma_issue_pending;
od->ddev.device_prep_dma_cyclic = bcm2835_dma_prep_dma_cyclic;
+ od->ddev.device_prep_slave_sg = bcm2835_dma_prep_slave_sg;
od->ddev.device_config = bcm2835_dma_slave_config;
od->ddev.device_terminate_all = bcm2835_dma_terminate_all;
od->ddev.src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
|
