drivers/i2c/busses/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 */
  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 != -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
  73 fail_rx:
  74         dma_release_channel(dma->chan_rx);
  75 fail_tx:
  76         dma_release_channel(dma->chan_tx);
  77 fail_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
  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
  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 }