1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * i2c-stm32.c
4 *
5 * Copyright (C) M'boumba Cedric Madianga 2017
6 * Author: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
7 */
8
9#include "i2c-stm32.h"
10
11/* Functions for DMA support */
12struct stm32_i2c_dma *stm32_i2c_dma_request(struct device *dev,
13 dma_addr_t phy_addr,
14 u32 txdr_offset,
15 u32 rxdr_offset)
16{
17 struct stm32_i2c_dma *dma;
18 struct dma_slave_config dma_sconfig;
19 int ret;
20
21 dma = devm_kzalloc(dev, size: sizeof(*dma), GFP_KERNEL);
22 if (!dma)
23 return ERR_PTR(error: -ENOMEM);
24
25 /* Request and configure I2C TX dma channel */
26 dma->chan_tx = dma_request_chan(dev, name: "tx");
27 if (IS_ERR(ptr: dma->chan_tx)) {
28 ret = PTR_ERR(ptr: dma->chan_tx);
29 if (ret != -ENODEV)
30 ret = dev_err_probe(dev, err: ret,
31 fmt: "can't request DMA tx channel\n");
32 goto fail_al;
33 }
34
35 memset(&dma_sconfig, 0, sizeof(dma_sconfig));
36 dma_sconfig.dst_addr = phy_addr + txdr_offset;
37 dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
38 dma_sconfig.dst_maxburst = 1;
39 dma_sconfig.direction = DMA_MEM_TO_DEV;
40 ret = dmaengine_slave_config(chan: dma->chan_tx, config: &dma_sconfig);
41 if (ret < 0) {
42 dev_err(dev, "can't configure tx channel\n");
43 goto fail_tx;
44 }
45
46 /* Request and configure I2C RX dma channel */
47 dma->chan_rx = dma_request_chan(dev, name: "rx");
48 if (IS_ERR(ptr: dma->chan_rx)) {
49 ret = PTR_ERR(ptr: dma->chan_rx);
50 if (ret != -ENODEV)
51 ret = dev_err_probe(dev, err: ret,
52 fmt: "can't request DMA rx channel\n");
53
54 goto fail_tx;
55 }
56
57 memset(&dma_sconfig, 0, sizeof(dma_sconfig));
58 dma_sconfig.src_addr = phy_addr + rxdr_offset;
59 dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
60 dma_sconfig.src_maxburst = 1;
61 dma_sconfig.direction = DMA_DEV_TO_MEM;
62 ret = dmaengine_slave_config(chan: dma->chan_rx, config: &dma_sconfig);
63 if (ret < 0) {
64 dev_err(dev, "can't configure rx channel\n");
65 goto fail_rx;
66 }
67
68 init_completion(x: &dma->dma_complete);
69
70 dev_info(dev, "using %s (tx) and %s (rx) for DMA transfers\n",
71 dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));
72
73 return dma;
74
75fail_rx:
76 dma_release_channel(chan: dma->chan_rx);
77fail_tx:
78 dma_release_channel(chan: dma->chan_tx);
79fail_al:
80 devm_kfree(dev, p: dma);
81
82 return ERR_PTR(error: ret);
83}
84
85void stm32_i2c_dma_free(struct stm32_i2c_dma *dma)
86{
87 dma->dma_buf = 0;
88 dma->dma_len = 0;
89
90 dma_release_channel(chan: dma->chan_tx);
91 dma->chan_tx = NULL;
92
93 dma_release_channel(chan: dma->chan_rx);
94 dma->chan_rx = NULL;
95
96 dma->chan_using = NULL;
97}
98
99int stm32_i2c_prep_dma_xfer(struct device *dev, struct stm32_i2c_dma *dma,
100 bool rd_wr, u32 len, u8 *buf,
101 dma_async_tx_callback callback,
102 void *dma_async_param)
103{
104 struct dma_async_tx_descriptor *txdesc;
105 struct device *chan_dev;
106 int ret;
107
108 if (rd_wr) {
109 dma->chan_using = dma->chan_rx;
110 dma->dma_transfer_dir = DMA_DEV_TO_MEM;
111 dma->dma_data_dir = DMA_FROM_DEVICE;
112 } else {
113 dma->chan_using = dma->chan_tx;
114 dma->dma_transfer_dir = DMA_MEM_TO_DEV;
115 dma->dma_data_dir = DMA_TO_DEVICE;
116 }
117
118 dma->dma_len = len;
119 chan_dev = dma->chan_using->device->dev;
120
121 dma->dma_buf = dma_map_single(chan_dev, buf, dma->dma_len,
122 dma->dma_data_dir);
123 if (dma_mapping_error(dev: chan_dev, dma_addr: dma->dma_buf)) {
124 dev_err(dev, "DMA mapping failed\n");
125 return -EINVAL;
126 }
127
128 txdesc = dmaengine_prep_slave_single(chan: dma->chan_using, buf: dma->dma_buf,
129 len: dma->dma_len,
130 dir: dma->dma_transfer_dir,
131 flags: DMA_PREP_INTERRUPT);
132 if (!txdesc) {
133 dev_err(dev, "Not able to get desc for DMA xfer\n");
134 ret = -EINVAL;
135 goto err;
136 }
137
138 reinit_completion(x: &dma->dma_complete);
139
140 txdesc->callback = callback;
141 txdesc->callback_param = dma_async_param;
142 ret = dma_submit_error(cookie: dmaengine_submit(desc: txdesc));
143 if (ret < 0) {
144 dev_err(dev, "DMA submit failed\n");
145 goto err;
146 }
147
148 dma_async_issue_pending(chan: dma->chan_using);
149
150 return 0;
151
152err:
153 dma_unmap_single(chan_dev, dma->dma_buf, dma->dma_len,
154 dma->dma_data_dir);
155 return ret;
156}
157

source code of linux/drivers/i2c/busses/i2c-stm32.c