1 /* 2 * PXA2xx SPI DMA engine support. 3 * 4 * Copyright (C) 2013, Intel Corporation 5 * Author: Mika Westerberg <mika.westerberg@linux.intel.com> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 */ 11 12 #include <linux/device.h> 13 #include <linux/dma-mapping.h> 14 #include <linux/dmaengine.h> 15 #include <linux/pxa2xx_ssp.h> 16 #include <linux/scatterlist.h> 17 #include <linux/sizes.h> 18 #include <linux/spi/spi.h> 19 #include <linux/spi/pxa2xx_spi.h> 20 21 #include "spi-pxa2xx.h" 22 23 static int pxa2xx_spi_map_dma_buffer(struct driver_data *drv_data, 24 enum dma_data_direction dir) 25 { 26 int i, nents, len = drv_data->len; 27 struct scatterlist *sg; 28 struct device *dmadev; 29 struct sg_table *sgt; 30 void *buf, *pbuf; 31 32 if (dir == DMA_TO_DEVICE) { 33 dmadev = drv_data->tx_chan->device->dev; 34 sgt = &drv_data->tx_sgt; 35 buf = drv_data->tx; 36 drv_data->tx_map_len = len; 37 } else { 38 dmadev = drv_data->rx_chan->device->dev; 39 sgt = &drv_data->rx_sgt; 40 buf = drv_data->rx; 41 drv_data->rx_map_len = len; 42 } 43 44 nents = DIV_ROUND_UP(len, SZ_2K); 45 if (nents != sgt->nents) { 46 int ret; 47 48 sg_free_table(sgt); 49 ret = sg_alloc_table(sgt, nents, GFP_ATOMIC); 50 if (ret) 51 return ret; 52 } 53 54 pbuf = buf; 55 for_each_sg(sgt->sgl, sg, sgt->nents, i) { 56 size_t bytes = min_t(size_t, len, SZ_2K); 57 58 if (buf) 59 sg_set_buf(sg, pbuf, bytes); 60 else 61 sg_set_buf(sg, drv_data->dummy, bytes); 62 63 pbuf += bytes; 64 len -= bytes; 65 } 66 67 nents = dma_map_sg(dmadev, sgt->sgl, sgt->nents, dir); 68 if (!nents) 69 return -ENOMEM; 70 71 return nents; 72 } 73 74 static void pxa2xx_spi_unmap_dma_buffer(struct driver_data *drv_data, 75 enum dma_data_direction dir) 76 { 77 struct device *dmadev; 78 struct sg_table *sgt; 79 80 if (dir == DMA_TO_DEVICE) { 81 dmadev = drv_data->tx_chan->device->dev; 82 sgt = &drv_data->tx_sgt; 83 } else { 84 dmadev = drv_data->rx_chan->device->dev; 85 sgt = &drv_data->rx_sgt; 86 } 87 88 dma_unmap_sg(dmadev, sgt->sgl, sgt->nents, dir); 89 } 90 91 static void pxa2xx_spi_unmap_dma_buffers(struct driver_data *drv_data) 92 { 93 if (!drv_data->dma_mapped) 94 return; 95 96 pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_FROM_DEVICE); 97 pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_TO_DEVICE); 98 99 drv_data->dma_mapped = 0; 100 } 101 102 static void pxa2xx_spi_dma_transfer_complete(struct driver_data *drv_data, 103 bool error) 104 { 105 struct spi_message *msg = drv_data->cur_msg; 106 107 /* 108 * It is possible that one CPU is handling ROR interrupt and other 109 * just gets DMA completion. Calling pump_transfers() twice for the 110 * same transfer leads to problems thus we prevent concurrent calls 111 * by using ->dma_running. 112 */ 113 if (atomic_dec_and_test(&drv_data->dma_running)) { 114 /* 115 * If the other CPU is still handling the ROR interrupt we 116 * might not know about the error yet. So we re-check the 117 * ROR bit here before we clear the status register. 118 */ 119 if (!error) { 120 u32 status = pxa2xx_spi_read(drv_data, SSSR) 121 & drv_data->mask_sr; 122 error = status & SSSR_ROR; 123 } 124 125 /* Clear status & disable interrupts */ 126 pxa2xx_spi_write(drv_data, SSCR1, 127 pxa2xx_spi_read(drv_data, SSCR1) 128 & ~drv_data->dma_cr1); 129 write_SSSR_CS(drv_data, drv_data->clear_sr); 130 if (!pxa25x_ssp_comp(drv_data)) 131 pxa2xx_spi_write(drv_data, SSTO, 0); 132 133 if (!error) { 134 pxa2xx_spi_unmap_dma_buffers(drv_data); 135 136 drv_data->tx += drv_data->tx_map_len; 137 drv_data->rx += drv_data->rx_map_len; 138 139 msg->actual_length += drv_data->len; 140 msg->state = pxa2xx_spi_next_transfer(drv_data); 141 } else { 142 /* In case we got an error we disable the SSP now */ 143 pxa2xx_spi_write(drv_data, SSCR0, 144 pxa2xx_spi_read(drv_data, SSCR0) 145 & ~SSCR0_SSE); 146 147 msg->state = ERROR_STATE; 148 } 149 150 tasklet_schedule(&drv_data->pump_transfers); 151 } 152 } 153 154 static void pxa2xx_spi_dma_callback(void *data) 155 { 156 pxa2xx_spi_dma_transfer_complete(data, false); 157 } 158 159 static struct dma_async_tx_descriptor * 160 pxa2xx_spi_dma_prepare_one(struct driver_data *drv_data, 161 enum dma_transfer_direction dir) 162 { 163 struct chip_data *chip = drv_data->cur_chip; 164 enum dma_slave_buswidth width; 165 struct dma_slave_config cfg; 166 struct dma_chan *chan; 167 struct sg_table *sgt; 168 int nents, ret; 169 170 switch (drv_data->n_bytes) { 171 case 1: 172 width = DMA_SLAVE_BUSWIDTH_1_BYTE; 173 break; 174 case 2: 175 width = DMA_SLAVE_BUSWIDTH_2_BYTES; 176 break; 177 default: 178 width = DMA_SLAVE_BUSWIDTH_4_BYTES; 179 break; 180 } 181 182 memset(&cfg, 0, sizeof(cfg)); 183 cfg.direction = dir; 184 185 if (dir == DMA_MEM_TO_DEV) { 186 cfg.dst_addr = drv_data->ssdr_physical; 187 cfg.dst_addr_width = width; 188 cfg.dst_maxburst = chip->dma_burst_size; 189 190 sgt = &drv_data->tx_sgt; 191 nents = drv_data->tx_nents; 192 chan = drv_data->tx_chan; 193 } else { 194 cfg.src_addr = drv_data->ssdr_physical; 195 cfg.src_addr_width = width; 196 cfg.src_maxburst = chip->dma_burst_size; 197 198 sgt = &drv_data->rx_sgt; 199 nents = drv_data->rx_nents; 200 chan = drv_data->rx_chan; 201 } 202 203 ret = dmaengine_slave_config(chan, &cfg); 204 if (ret) { 205 dev_warn(&drv_data->pdev->dev, "DMA slave config failed\n"); 206 return NULL; 207 } 208 209 return dmaengine_prep_slave_sg(chan, sgt->sgl, nents, dir, 210 DMA_PREP_INTERRUPT | DMA_CTRL_ACK); 211 } 212 213 bool pxa2xx_spi_dma_is_possible(size_t len) 214 { 215 return len <= MAX_DMA_LEN; 216 } 217 218 int pxa2xx_spi_map_dma_buffers(struct driver_data *drv_data) 219 { 220 const struct chip_data *chip = drv_data->cur_chip; 221 int ret; 222 223 if (!chip->enable_dma) 224 return 0; 225 226 /* Don't bother with DMA if we can't do even a single burst */ 227 if (drv_data->len < chip->dma_burst_size) 228 return 0; 229 230 ret = pxa2xx_spi_map_dma_buffer(drv_data, DMA_TO_DEVICE); 231 if (ret <= 0) { 232 dev_warn(&drv_data->pdev->dev, "failed to DMA map TX\n"); 233 return 0; 234 } 235 236 drv_data->tx_nents = ret; 237 238 ret = pxa2xx_spi_map_dma_buffer(drv_data, DMA_FROM_DEVICE); 239 if (ret <= 0) { 240 pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_TO_DEVICE); 241 dev_warn(&drv_data->pdev->dev, "failed to DMA map RX\n"); 242 return 0; 243 } 244 245 drv_data->rx_nents = ret; 246 return 1; 247 } 248 249 irqreturn_t pxa2xx_spi_dma_transfer(struct driver_data *drv_data) 250 { 251 u32 status; 252 253 status = pxa2xx_spi_read(drv_data, SSSR) & drv_data->mask_sr; 254 if (status & SSSR_ROR) { 255 dev_err(&drv_data->pdev->dev, "FIFO overrun\n"); 256 257 dmaengine_terminate_all(drv_data->rx_chan); 258 dmaengine_terminate_all(drv_data->tx_chan); 259 260 pxa2xx_spi_dma_transfer_complete(drv_data, true); 261 return IRQ_HANDLED; 262 } 263 264 return IRQ_NONE; 265 } 266 267 int pxa2xx_spi_dma_prepare(struct driver_data *drv_data, u32 dma_burst) 268 { 269 struct dma_async_tx_descriptor *tx_desc, *rx_desc; 270 271 tx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_MEM_TO_DEV); 272 if (!tx_desc) { 273 dev_err(&drv_data->pdev->dev, 274 "failed to get DMA TX descriptor\n"); 275 return -EBUSY; 276 } 277 278 rx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_DEV_TO_MEM); 279 if (!rx_desc) { 280 dev_err(&drv_data->pdev->dev, 281 "failed to get DMA RX descriptor\n"); 282 return -EBUSY; 283 } 284 285 /* We are ready when RX completes */ 286 rx_desc->callback = pxa2xx_spi_dma_callback; 287 rx_desc->callback_param = drv_data; 288 289 dmaengine_submit(rx_desc); 290 dmaengine_submit(tx_desc); 291 return 0; 292 } 293 294 void pxa2xx_spi_dma_start(struct driver_data *drv_data) 295 { 296 dma_async_issue_pending(drv_data->rx_chan); 297 dma_async_issue_pending(drv_data->tx_chan); 298 299 atomic_set(&drv_data->dma_running, 1); 300 } 301 302 int pxa2xx_spi_dma_setup(struct driver_data *drv_data) 303 { 304 struct pxa2xx_spi_master *pdata = drv_data->master_info; 305 struct device *dev = &drv_data->pdev->dev; 306 dma_cap_mask_t mask; 307 308 dma_cap_zero(mask); 309 dma_cap_set(DMA_SLAVE, mask); 310 311 drv_data->dummy = devm_kzalloc(dev, SZ_2K, GFP_KERNEL); 312 if (!drv_data->dummy) 313 return -ENOMEM; 314 315 drv_data->tx_chan = dma_request_slave_channel_compat(mask, 316 pdata->dma_filter, pdata->tx_param, dev, "tx"); 317 if (!drv_data->tx_chan) 318 return -ENODEV; 319 320 drv_data->rx_chan = dma_request_slave_channel_compat(mask, 321 pdata->dma_filter, pdata->rx_param, dev, "rx"); 322 if (!drv_data->rx_chan) { 323 dma_release_channel(drv_data->tx_chan); 324 drv_data->tx_chan = NULL; 325 return -ENODEV; 326 } 327 328 return 0; 329 } 330 331 void pxa2xx_spi_dma_release(struct driver_data *drv_data) 332 { 333 if (drv_data->rx_chan) { 334 dmaengine_terminate_all(drv_data->rx_chan); 335 dma_release_channel(drv_data->rx_chan); 336 sg_free_table(&drv_data->rx_sgt); 337 drv_data->rx_chan = NULL; 338 } 339 if (drv_data->tx_chan) { 340 dmaengine_terminate_all(drv_data->tx_chan); 341 dma_release_channel(drv_data->tx_chan); 342 sg_free_table(&drv_data->tx_sgt); 343 drv_data->tx_chan = NULL; 344 } 345 } 346 347 int pxa2xx_spi_set_dma_burst_and_threshold(struct chip_data *chip, 348 struct spi_device *spi, 349 u8 bits_per_word, u32 *burst_code, 350 u32 *threshold) 351 { 352 struct pxa2xx_spi_chip *chip_info = spi->controller_data; 353 354 /* 355 * If the DMA burst size is given in chip_info we use that, 356 * otherwise we use the default. Also we use the default FIFO 357 * thresholds for now. 358 */ 359 *burst_code = chip_info ? chip_info->dma_burst_size : 1; 360 *threshold = SSCR1_RxTresh(RX_THRESH_DFLT) 361 | SSCR1_TxTresh(TX_THRESH_DFLT); 362 363 return 0; 364 } 365