drivers/i2c/busses/i2c-stm32.c

   1 /*
   2  * i2c-stm32.c
   3  *
   4  * Copyright (C) M'boumba Cedric Madianga 2017
   5  * Author: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
   6  *
   7  * License terms:  GNU General Public License (GPL), version 2
   8  */
   9
  10 #include "i2c-stm32.h"
  11
  12 /* Functions for DMA support */
  13 struct stm32_i2c_dma *stm32_i2c_dma_request(struct device *dev,
  14                                             dma_addr_t phy_addr,
  15                                             u32 txdr_offset,
  16                                             u32 rxdr_offset)
  17 {
  18         struct stm32_i2c_dma *dma;
  19         struct dma_slave_config dma_sconfig;
  20         int ret;
  21
  22         dma = devm_kzalloc(dev, sizeof(*dma), GFP_KERNEL);
  23         if (!dma)
  24                 return ERR_PTR(-ENOMEM);
  25
  26         /* Request and configure I2C TX dma channel */
  27         dma->chan_tx = dma_request_chan(dev, "tx");
  28         if (IS_ERR(dma->chan_tx)) {
  29                 dev_dbg(dev, "can't request DMA tx channel\n");
  30                 ret = PTR_ERR(dma->chan_tx);
  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                 dev_err(dev, "can't request DMA rx channel\n");
  49                 ret = PTR_ERR(dma->chan_rx);
  50                 goto fail_tx;
  51         }
  52
  53         memset(&dma_sconfig, 0, sizeof(dma_sconfig));
  54         dma_sconfig.src_addr = phy_addr + rxdr_offset;
  55         dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
  56         dma_sconfig.src_maxburst = 1;
  57         dma_sconfig.direction = DMA_DEV_TO_MEM;
  58         ret = dmaengine_slave_config(dma->chan_rx, &dma_sconfig);
  59         if (ret < 0) {
  60                 dev_err(dev, "can't configure rx channel\n");
  61                 goto fail_rx;
  62         }
  63
  64         init_completion(&dma->dma_complete);
  65
  66         dev_info(dev, "using %s (tx) and %s (rx) for DMA transfers\n",
  67                  dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));
  68
  69         return dma;
  70
  71 fail_rx:
  72         dma_release_channel(dma->chan_rx);
  73 fail_tx:
  74         dma_release_channel(dma->chan_tx);
  75 fail_al:
  76         devm_kfree(dev, dma);
  77         dev_info(dev, "can't use DMA\n");
  78
  79         return ERR_PTR(ret);
  80 }
  81
  82 void stm32_i2c_dma_free(struct stm32_i2c_dma *dma)
  83 {
  84         dma->dma_buf = 0;
  85         dma->dma_len = 0;
  86
  87         dma_release_channel(dma->chan_tx);
  88         dma->chan_tx = NULL;
  89
  90         dma_release_channel(dma->chan_rx);
  91         dma->chan_rx = NULL;
  92
  93         dma->chan_using = NULL;
  94 }
  95
  96 int stm32_i2c_prep_dma_xfer(struct device *dev, struct stm32_i2c_dma *dma,
  97                             bool rd_wr, u32 len, u8 *buf,
  98                             dma_async_tx_callback callback,
  99                             void *dma_async_param)
 100 {
 101         struct dma_async_tx_descriptor *txdesc;
 102         struct device *chan_dev;
 103         int ret;
 104
 105         if (rd_wr) {
 106                 dma->chan_using = dma->chan_rx;
 107                 dma->dma_transfer_dir = DMA_DEV_TO_MEM;
 108                 dma->dma_data_dir = DMA_FROM_DEVICE;
 109         } else {
 110                 dma->chan_using = dma->chan_tx;
 111                 dma->dma_transfer_dir = DMA_MEM_TO_DEV;
 112                 dma->dma_data_dir = DMA_TO_DEVICE;
 113         }
 114
 115         dma->dma_len = len;
 116         chan_dev = dma->chan_using->device->dev;
 117
 118         dma->dma_buf = dma_map_single(chan_dev, buf, dma->dma_len,
 119                                       dma->dma_data_dir);
 120         if (dma_mapping_error(chan_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
 149 err:
 150         dma_unmap_single(chan_dev, dma->dma_buf, dma->dma_len,
 151                          dma->dma_data_dir);
 152         return ret;
 153 }