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