i2c-stm32.c

  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 != -ENODEV)
 30			dev_err_probe(dev, ret, "can't request DMA tx channel\n");
 31
 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			dev_err_probe(dev, ret, "can't request DMA rx channel\n");
 52
 53		goto fail_tx;
 54	}
 55
 56	memset(&dma_sconfig, 0, sizeof(dma_sconfig));
 57	dma_sconfig.src_addr = phy_addr + rxdr_offset;
 58	dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
 59	dma_sconfig.src_maxburst = 1;
 60	dma_sconfig.direction = DMA_DEV_TO_MEM;
 61	ret = dmaengine_slave_config(dma->chan_rx, &dma_sconfig);
 62	if (ret < 0) {
 63		dev_err(dev, "can't configure rx channel\n");
 64		goto fail_rx;
 65	}
 66
 67	init_completion(&dma->dma_complete);
 68
 69	dev_info(dev, "using %s (tx) and %s (rx) for DMA transfers\n",
 70		 dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));
 71
 72	return dma;
 73
 74fail_rx:
 75	dma_release_channel(dma->chan_rx);
 76fail_tx:
 77	dma_release_channel(dma->chan_tx);
 78fail_al:
 79	devm_kfree(dev, dma);
 80
 81	return ERR_PTR(ret);
 82}
 83
 84void stm32_i2c_dma_free(struct stm32_i2c_dma *dma)
 85{
 86	dma->dma_buf = 0;
 87	dma->dma_len = 0;
 88
 89	dma_release_channel(dma->chan_tx);
 90	dma->chan_tx = NULL;
 91
 92	dma_release_channel(dma->chan_rx);
 93	dma->chan_rx = NULL;
 94
 95	dma->chan_using = NULL;
 96}
 97
 98int stm32_i2c_prep_dma_xfer(struct device *dev, struct stm32_i2c_dma *dma,
 99			    bool rd_wr, u32 len, u8 *buf,
100			    dma_async_tx_callback callback,
101			    void *dma_async_param)
102{
103	struct dma_async_tx_descriptor *txdesc;
104	int ret;
105
106	if (rd_wr) {
107		dma->chan_using = dma->chan_rx;
108		dma->dma_transfer_dir = DMA_DEV_TO_MEM;
109		dma->dma_data_dir = DMA_FROM_DEVICE;
110	} else {
111		dma->chan_using = dma->chan_tx;
112		dma->dma_transfer_dir = DMA_MEM_TO_DEV;
113		dma->dma_data_dir = DMA_TO_DEVICE;
114	}
115
116	dma->dma_len = len;
117
118	dma->dma_buf = dma_map_single(dev, buf, dma->dma_len,
119				      dma->dma_data_dir);
120	if (dma_mapping_error(dev, dma->dma_buf)) {
121		dev_err(dev, "DMA mapping failed\n");
122		return -EINVAL;
123	}
124
125	txdesc = dmaengine_prep_slave_single(dma->chan_using, dma->dma_buf,
126					     dma->dma_len,
127					     dma->dma_transfer_dir,
128					     DMA_PREP_INTERRUPT);
129	if (!txdesc) {
130		dev_err(dev, "Not able to get desc for DMA xfer\n");
131		ret = -EINVAL;
132		goto err;
133	}
134
135	reinit_completion(&dma->dma_complete);
136
137	txdesc->callback = callback;
138	txdesc->callback_param = dma_async_param;
139	ret = dma_submit_error(dmaengine_submit(txdesc));
140	if (ret < 0) {
141		dev_err(dev, "DMA submit failed\n");
142		goto err;
143	}
144
145	dma_async_issue_pending(dma->chan_using);
146
147	return 0;
148
149err:
150	dma_unmap_single(dev, dma->dma_buf, dma->dma_len,
151			 dma->dma_data_dir);
152	return ret;
153}