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, 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 != -EPROBE_DEFER)
 30			dev_err(dev, "can't request DMA tx channel\n");
 31		goto fail_al;
 32	}
 33
 34	memset(&dma_sconfig, 0, sizeof(dma_sconfig));
 35	dma_sconfig.dst_addr = phy_addr + txdr_offset;
 36	dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
 37	dma_sconfig.dst_maxburst = 1;
 38	dma_sconfig.direction = DMA_MEM_TO_DEV;
 39	ret = dmaengine_slave_config(dma->chan_tx, &dma_sconfig);
 40	if (ret < 0) {
 41		dev_err(dev, "can't configure tx channel\n");
 42		goto fail_tx;
 43	}
 44
 45	/* Request and configure I2C RX dma channel */
 46	dma->chan_rx = dma_request_chan(dev, "rx");
 47	if (IS_ERR(dma->chan_rx)) {
 48		ret = PTR_ERR(dma->chan_rx);
 49		if (ret != -EPROBE_DEFER)
 50			dev_err(dev, "can't request DMA rx channel\n");
 51
 52		goto fail_tx;
 53	}
 54
 55	memset(&dma_sconfig, 0, sizeof(dma_sconfig));
 56	dma_sconfig.src_addr = phy_addr + rxdr_offset;
 57	dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
 58	dma_sconfig.src_maxburst = 1;
 59	dma_sconfig.direction = DMA_DEV_TO_MEM;
 60	ret = dmaengine_slave_config(dma->chan_rx, &dma_sconfig);
 61	if (ret < 0) {
 62		dev_err(dev, "can't configure rx channel\n");
 63		goto fail_rx;
 64	}
 65
 66	init_completion(&dma->dma_complete);
 67
 68	dev_info(dev, "using %s (tx) and %s (rx) for DMA transfers\n",
 69		 dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));
 70
 71	return dma;
 72
 73fail_rx:
 74	dma_release_channel(dma->chan_rx);
 75fail_tx:
 76	dma_release_channel(dma->chan_tx);
 77fail_al:
 78	devm_kfree(dev, dma);
 79	if (ret != -EPROBE_DEFER)
 80		dev_info(dev, "can't use DMA\n");
 81
 82	return ERR_PTR(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(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
 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(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
152err:
153	dma_unmap_single(chan_dev, dma->dma_buf, dma->dma_len,
154			 dma->dma_data_dir);
155	return ret;
156}