drivers/spi/ti-ssp-spi.c

   1 /*
   2  * Sequencer Serial Port (SSP) based SPI master driver
   3  *
   4  * Copyright (C) 2010 Texas Instruments Inc
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/err.h>
  23 #include <linux/completion.h>
  24 #include <linux/delay.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/spi/spi.h>
  27 #include <linux/mfd/ti_ssp.h>
  28
  29 #define MODE_BITS       (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH)
  30
  31 struct ti_ssp_spi {
  32         struct spi_master               *master;
  33         struct device                   *dev;
  34         spinlock_t                      lock;
  35         struct list_head                msg_queue;
  36         struct completion               complete;
  37         bool                            shutdown;
  38         struct workqueue_struct         *workqueue;
  39         struct work_struct              work;
  40         u8                              mode, bpw;
  41         int                             cs_active;
  42         u32                             pc_en, pc_dis, pc_wr, pc_rd;
  43         void                            (*select)(int cs);
  44 };
  45
  46 static u32 ti_ssp_spi_rx(struct ti_ssp_spi *hw)
  47 {
  48         u32 ret;
  49
  50         ti_ssp_run(hw->dev, hw->pc_rd, 0, &ret);
  51         return ret;
  52 }
  53
  54 static void ti_ssp_spi_tx(struct ti_ssp_spi *hw, u32 data)
  55 {
  56         ti_ssp_run(hw->dev, hw->pc_wr, data << (32 - hw->bpw), NULL);
  57 }
  58
  59 static int ti_ssp_spi_txrx(struct ti_ssp_spi *hw, struct spi_message *msg,
  60                        struct spi_transfer *t)
  61 {
  62         int count;
  63
  64         if (hw->bpw <= 8) {
  65                 u8              *rx = t->rx_buf;
  66                 const u8        *tx = t->tx_buf;
  67
  68                 for (count = 0; count < t->len; count += 1) {
  69                         if (t->tx_buf)
  70                                 ti_ssp_spi_tx(hw, *tx++);
  71                         if (t->rx_buf)
  72                                 *rx++ = ti_ssp_spi_rx(hw);
  73                 }
  74         } else if (hw->bpw <= 16) {
  75                 u16             *rx = t->rx_buf;
  76                 const u16       *tx = t->tx_buf;
  77
  78                 for (count = 0; count < t->len; count += 2) {
  79                         if (t->tx_buf)
  80                                 ti_ssp_spi_tx(hw, *tx++);
  81                         if (t->rx_buf)
  82                                 *rx++ = ti_ssp_spi_rx(hw);
  83                 }
  84         } else {
  85                 u32             *rx = t->rx_buf;
  86                 const u32       *tx = t->tx_buf;
  87
  88                 for (count = 0; count < t->len; count += 4) {
  89                         if (t->tx_buf)
  90                                 ti_ssp_spi_tx(hw, *tx++);
  91                         if (t->rx_buf)
  92                                 *rx++ = ti_ssp_spi_rx(hw);
  93                 }
  94         }
  95
  96         msg->actual_length += count; /* bytes transferred */
  97
  98         dev_dbg(&msg->spi->dev, "xfer %s%s, %d bytes, %d bpw, count %d%s\n",
  99                 t->tx_buf ? "tx" : "", t->rx_buf ? "rx" : "", t->len,
 100                 hw->bpw, count, (count < t->len) ? " (under)" : "");
 101
 102         return (count < t->len) ? -EIO : 0; /* left over data */
 103 }
 104
 105 static void ti_ssp_spi_chip_select(struct ti_ssp_spi *hw, int cs_active)
 106 {
 107         cs_active = !!cs_active;
 108         if (cs_active == hw->cs_active)
 109                 return;
 110         ti_ssp_run(hw->dev, cs_active ? hw->pc_en : hw->pc_dis, 0, NULL);
 111         hw->cs_active = cs_active;
 112 }
 113
 114 #define __SHIFT_OUT(bits)       (SSP_OPCODE_SHIFT | SSP_OUT_MODE | \
 115                                  cs_en | clk | SSP_COUNT((bits) * 2 - 1))
 116 #define __SHIFT_IN(bits)        (SSP_OPCODE_SHIFT | SSP_IN_MODE  | \
 117                                  cs_en | clk | SSP_COUNT((bits) * 2 - 1))
 118
 119 static int ti_ssp_spi_setup_transfer(struct ti_ssp_spi *hw, u8 bpw, u8 mode)
 120 {
 121         int error, idx = 0;
 122         u32 seqram[16];
 123         u32 cs_en, cs_dis, clk;
 124         u32 topbits, botbits;
 125
 126         mode &= MODE_BITS;
 127         if (mode == hw->mode && bpw == hw->bpw)
 128                 return 0;
 129
 130         cs_en  = (mode & SPI_CS_HIGH) ? SSP_CS_HIGH : SSP_CS_LOW;
 131         cs_dis = (mode & SPI_CS_HIGH) ? SSP_CS_LOW  : SSP_CS_HIGH;
 132         clk    = (mode & SPI_CPOL)    ? SSP_CLK_HIGH : SSP_CLK_LOW;
 133
 134         /* Construct instructions */
 135
 136         /* Disable Chip Select */
 137         hw->pc_dis = idx;
 138         seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_dis | clk;
 139         seqram[idx++] = SSP_OPCODE_STOP   | SSP_OUT_MODE | cs_dis | clk;
 140
 141         /* Enable Chip Select */
 142         hw->pc_en = idx;
 143         seqram[idx++] = SSP_OPCODE_DIRECT | SSP_OUT_MODE | cs_en | clk;
 144         seqram[idx++] = SSP_OPCODE_STOP   | SSP_OUT_MODE | cs_en | clk;
 145
 146         /* Reads and writes need to be split for bpw > 16 */
 147         topbits = (bpw > 16) ? 16 : bpw;
 148         botbits = bpw - topbits;
 149
 150         /* Write */
 151         hw->pc_wr = idx;
 152         seqram[idx++] = __SHIFT_OUT(topbits) | SSP_ADDR_REG;
 153         if (botbits)
 154                 seqram[idx++] = __SHIFT_OUT(botbits)  | SSP_DATA_REG;
 155         seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
 156
 157         /* Read */
 158         hw->pc_rd = idx;
 159         if (botbits)
 160                 seqram[idx++] = __SHIFT_IN(botbits) | SSP_ADDR_REG;
 161         seqram[idx++] = __SHIFT_IN(topbits) | SSP_DATA_REG;
 162         seqram[idx++] = SSP_OPCODE_STOP | SSP_OUT_MODE | cs_en | clk;
 163
 164         error = ti_ssp_load(hw->dev, 0, seqram, idx);
 165         if (error < 0)
 166                 return error;
 167
 168         error = ti_ssp_set_mode(hw->dev, ((mode & SPI_CPHA) ?
 169                                           0 : SSP_EARLY_DIN));
 170         if (error < 0)
 171                 return error;
 172
 173         hw->bpw = bpw;
 174         hw->mode = mode;
 175
 176         return error;
 177 }
 178
 179 static void ti_ssp_spi_work(struct work_struct *work)
 180 {
 181         struct ti_ssp_spi *hw = container_of(work, struct ti_ssp_spi, work);
 182
 183         spin_lock(&hw->lock);
 184
 185          while (!list_empty(&hw->msg_queue)) {
 186                 struct spi_message      *m;
 187                 struct spi_device       *spi;
 188                 struct spi_transfer     *t = NULL;
 189                 int                     status = 0;
 190
 191                 m = container_of(hw->msg_queue.next, struct spi_message,
 192                                  queue);
 193
 194                 list_del_init(&m->queue);
 195
 196                 spin_unlock(&hw->lock);
 197
 198                 spi = m->spi;
 199
 200                 if (hw->select)
 201                         hw->select(spi->chip_select);
 202
 203                 list_for_each_entry(t, &m->transfers, transfer_list) {
 204                         int bpw = spi->bits_per_word;
 205                         int xfer_status;
 206
 207                         if (t->bits_per_word)
 208                                 bpw = t->bits_per_word;
 209
 210                         if (ti_ssp_spi_setup_transfer(hw, bpw, spi->mode) < 0)
 211                                 break;
 212
 213                         ti_ssp_spi_chip_select(hw, 1);
 214
 215                         xfer_status = ti_ssp_spi_txrx(hw, m, t);
 216                         if (xfer_status < 0)
 217                                 status = xfer_status;
 218
 219                         if (t->delay_usecs)
 220                                 udelay(t->delay_usecs);
 221
 222                         if (t->cs_change)
 223                                 ti_ssp_spi_chip_select(hw, 0);
 224                 }
 225
 226                 ti_ssp_spi_chip_select(hw, 0);
 227                 m->status = status;
 228                 m->complete(m->context);
 229
 230                 spin_lock(&hw->lock);
 231         }
 232
 233         if (hw->shutdown)
 234                 complete(&hw->complete);
 235
 236         spin_unlock(&hw->lock);
 237 }
 238
 239 static int ti_ssp_spi_setup(struct spi_device *spi)
 240 {
 241         if (spi->bits_per_word > 32)
 242                 return -EINVAL;
 243
 244         return 0;
 245 }
 246
 247 static int ti_ssp_spi_transfer(struct spi_device *spi, struct spi_message *m)
 248 {
 249         struct ti_ssp_spi       *hw;
 250         struct spi_transfer     *t;
 251         int                     error = 0;
 252
 253         m->actual_length = 0;
 254         m->status = -EINPROGRESS;
 255
 256         hw = spi_master_get_devdata(spi->master);
 257
 258         if (list_empty(&m->transfers) || !m->complete)
 259                 return -EINVAL;
 260
 261         list_for_each_entry(t, &m->transfers, transfer_list) {
 262                 if (t->len && !(t->rx_buf || t->tx_buf)) {
 263                         dev_err(&spi->dev, "invalid xfer, no buffer\n");
 264                         return -EINVAL;
 265                 }
 266
 267                 if (t->len && t->rx_buf && t->tx_buf) {
 268                         dev_err(&spi->dev, "invalid xfer, full duplex\n");
 269                         return -EINVAL;
 270                 }
 271
 272                 if (t->bits_per_word > 32) {
 273                         dev_err(&spi->dev, "invalid xfer width %d\n",
 274                                 t->bits_per_word);
 275                         return -EINVAL;
 276                 }
 277         }
 278
 279         spin_lock(&hw->lock);
 280         if (hw->shutdown) {
 281                 error = -ESHUTDOWN;
 282                 goto error_unlock;
 283         }
 284         list_add_tail(&m->queue, &hw->msg_queue);
 285         queue_work(hw->workqueue, &hw->work);
 286 error_unlock:
 287         spin_unlock(&hw->lock);
 288         return error;
 289 }
 290
 291 static int __devinit ti_ssp_spi_probe(struct platform_device *pdev)
 292 {
 293         const struct ti_ssp_spi_data *pdata;
 294         struct ti_ssp_spi *hw;
 295         struct spi_master *master;
 296         struct device *dev = &pdev->dev;
 297         int error = 0;
 298
 299         pdata = dev->platform_data;
 300         if (!pdata) {
 301                 dev_err(dev, "platform data not found\n");
 302                 return -EINVAL;
 303         }
 304
 305         master = spi_alloc_master(dev, sizeof(struct ti_ssp_spi));
 306         if (!master) {
 307                 dev_err(dev, "cannot allocate SPI master\n");
 308                 return -ENOMEM;
 309         }
 310
 311         hw = spi_master_get_devdata(master);
 312         platform_set_drvdata(pdev, hw);
 313
 314         hw->master = master;
 315         hw->dev = dev;
 316         hw->select = pdata->select;
 317
 318         spin_lock_init(&hw->lock);
 319         init_completion(&hw->complete);
 320         INIT_LIST_HEAD(&hw->msg_queue);
 321         INIT_WORK(&hw->work, ti_ssp_spi_work);
 322
 323         hw->workqueue = create_singlethread_workqueue(dev_name(dev));
 324         if (!hw->workqueue) {
 325                 error = -ENOMEM;
 326                 dev_err(dev, "work queue creation failed\n");
 327                 goto error_wq;
 328         }
 329
 330         error = ti_ssp_set_iosel(hw->dev, pdata->iosel);
 331         if (error < 0) {
 332                 dev_err(dev, "io setup failed\n");
 333                 goto error_iosel;
 334         }
 335
 336         master->bus_num         = pdev->id;
 337         master->num_chipselect  = pdata->num_cs;
 338         master->mode_bits       = MODE_BITS;
 339         master->flags           = SPI_MASTER_HALF_DUPLEX;
 340         master->setup           = ti_ssp_spi_setup;
 341         master->transfer        = ti_ssp_spi_transfer;
 342
 343         error = spi_register_master(master);
 344         if (error) {
 345                 dev_err(dev, "master registration failed\n");
 346                 goto error_reg;
 347         }
 348
 349         return 0;
 350
 351 error_reg:
 352 error_iosel:
 353         destroy_workqueue(hw->workqueue);
 354 error_wq:
 355         spi_master_put(master);
 356         return error;
 357 }
 358
 359 static int __devexit ti_ssp_spi_remove(struct platform_device *pdev)
 360 {
 361         struct ti_ssp_spi *hw = platform_get_drvdata(pdev);
 362         int error;
 363
 364         hw->shutdown = 1;
 365         while (!list_empty(&hw->msg_queue)) {
 366                 error = wait_for_completion_interruptible(&hw->complete);
 367                 if (error < 0) {
 368                         hw->shutdown = 0;
 369                         return error;
 370                 }
 371         }
 372         destroy_workqueue(hw->workqueue);
 373         spi_unregister_master(hw->master);
 374
 375         return 0;
 376 }
 377
 378 static struct platform_driver ti_ssp_spi_driver = {
 379         .probe          = ti_ssp_spi_probe,
 380         .remove         = __devexit_p(ti_ssp_spi_remove),
 381         .driver         = {
 382                 .name   = "ti-ssp-spi",
 383                 .owner  = THIS_MODULE,
 384         },
 385 };
 386
 387 static int __init ti_ssp_spi_init(void)
 388 {
 389         return platform_driver_register(&ti_ssp_spi_driver);
 390 }
 391 module_init(ti_ssp_spi_init);
 392
 393 static void __exit ti_ssp_spi_exit(void)
 394 {
 395         platform_driver_unregister(&ti_ssp_spi_driver);
 396 }
 397 module_exit(ti_ssp_spi_exit);
 398
 399 MODULE_DESCRIPTION("SSP SPI Master");
 400 MODULE_AUTHOR("Cyril Chemparathy");
 401 MODULE_LICENSE("GPL");
 402 MODULE_ALIAS("platform:ti-ssp-spi");