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 */
stm32_i2c_dma_request(struct device * dev,dma_addr_t phy_addr,u32 txdr_offset,u32 rxdr_offset)12 struct 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, sizeof(*dma), GFP_KERNEL);
22 	if (!dma)
23 		return ERR_PTR(-ENOMEM);
24 
25 	/* Request and configure I2C TX dma channel */
26 	dma->chan_tx = dma_request_chan(dev, "tx");
27 	if (IS_ERR(dma->chan_tx)) {
28 		ret = PTR_ERR(dma->chan_tx);
29 		if (ret != -ENODEV)
30 			ret = dev_err_probe(dev, ret,
31 					    "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(dma->chan_tx, &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, "rx");
48 	if (IS_ERR(dma->chan_rx)) {
49 		ret = PTR_ERR(dma->chan_rx);
50 		if (ret != -ENODEV)
51 			ret = dev_err_probe(dev, ret,
52 					    "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(dma->chan_rx, &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(&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 
75 fail_rx:
76 	dma_release_channel(dma->chan_rx);
77 fail_tx:
78 	dma_release_channel(dma->chan_tx);
79 fail_al:
80 	devm_kfree(dev, dma);
81 
82 	return ERR_PTR(ret);
83 }
84 
stm32_i2c_dma_free(struct stm32_i2c_dma * dma)85 void 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(dma->chan_tx);
91 	dma->chan_tx = NULL;
92 
93 	dma_release_channel(dma->chan_rx);
94 	dma->chan_rx = NULL;
95 
96 	dma->chan_using = NULL;
97 }
98 
stm32_i2c_prep_dma_xfer(struct device * dev,struct stm32_i2c_dma * dma,bool rd_wr,u32 len,u8 * buf,dma_async_tx_callback callback,void * dma_async_param)99 int 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(chan_dev, dma->dma_buf)) {
124 		dev_err(dev, "DMA mapping failed\n");
125 		return -EINVAL;
126 	}
127 
128 	txdesc = dmaengine_prep_slave_single(dma->chan_using, dma->dma_buf,
129 					     dma->dma_len,
130 					     dma->dma_transfer_dir,
131 					     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(&dma->dma_complete);
139 
140 	txdesc->callback = callback;
141 	txdesc->callback_param = dma_async_param;
142 	ret = dma_submit_error(dmaengine_submit(txdesc));
143 	if (ret < 0) {
144 		dev_err(dev, "DMA submit failed\n");
145 		goto err;
146 	}
147 
148 	dma_async_issue_pending(dma->chan_using);
149 
150 	return 0;
151 
152 err:
153 	dma_unmap_single(chan_dev, dma->dma_buf, dma->dma_len,
154 			 dma->dma_data_dir);
155 	return ret;
156 }
157