drivers/spi/spi-orion.c

   1 /*
   2  * Marvell Orion SPI controller driver
   3  *
   4  * Author: Shadi Ammouri <shadi@marvell.com>
   5  * Copyright (C) 2007-2008 Marvell Ltd.
   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/interrupt.h>
  13 #include <linux/delay.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/err.h>
  16 #include <linux/io.h>
  17 #include <linux/spi/spi.h>
  18 #include <linux/module.h>
  19 #include <linux/of.h>
  20 #include <linux/clk.h>
  21 #include <linux/sizes.h>
  22 #include <asm/unaligned.h>
  23
  24 #define DRIVER_NAME                     "orion_spi"
  25
  26 #define ORION_NUM_CHIPSELECTS           1 /* only one slave is supported*/
  27 #define ORION_SPI_WAIT_RDY_MAX_LOOP     2000 /* in usec */
  28
  29 #define ORION_SPI_IF_CTRL_REG           0x00
  30 #define ORION_SPI_IF_CONFIG_REG         0x04
  31 #define ORION_SPI_DATA_OUT_REG          0x08
  32 #define ORION_SPI_DATA_IN_REG           0x0c
  33 #define ORION_SPI_INT_CAUSE_REG         0x10
  34
  35 #define ORION_SPI_MODE_CPOL             (1 << 11)
  36 #define ORION_SPI_MODE_CPHA             (1 << 12)
  37 #define ORION_SPI_IF_8_16_BIT_MODE      (1 << 5)
  38 #define ORION_SPI_CLK_PRESCALE_MASK     0x1F
  39 #define ORION_SPI_MODE_MASK             (ORION_SPI_MODE_CPOL | \
  40                                          ORION_SPI_MODE_CPHA)
  41
  42 struct orion_spi {
  43         struct spi_master       *master;
  44         void __iomem            *base;
  45         struct clk              *clk;
  46 };
  47
  48 static inline void __iomem *spi_reg(struct orion_spi *orion_spi, u32 reg)
  49 {
  50         return orion_spi->base + reg;
  51 }
  52
  53 static inline void
  54 orion_spi_setbits(struct orion_spi *orion_spi, u32 reg, u32 mask)
  55 {
  56         void __iomem *reg_addr = spi_reg(orion_spi, reg);
  57         u32 val;
  58
  59         val = readl(reg_addr);
  60         val |= mask;
  61         writel(val, reg_addr);
  62 }
  63
  64 static inline void
  65 orion_spi_clrbits(struct orion_spi *orion_spi, u32 reg, u32 mask)
  66 {
  67         void __iomem *reg_addr = spi_reg(orion_spi, reg);
  68         u32 val;
  69
  70         val = readl(reg_addr);
  71         val &= ~mask;
  72         writel(val, reg_addr);
  73 }
  74
  75 static int orion_spi_baudrate_set(struct spi_device *spi, unsigned int speed)
  76 {
  77         u32 tclk_hz;
  78         u32 rate;
  79         u32 prescale;
  80         u32 reg;
  81         struct orion_spi *orion_spi;
  82
  83         orion_spi = spi_master_get_devdata(spi->master);
  84
  85         tclk_hz = clk_get_rate(orion_spi->clk);
  86
  87         /*
  88          * the supported rates are: 4,6,8...30
  89          * round up as we look for equal or less speed
  90          */
  91         rate = DIV_ROUND_UP(tclk_hz, speed);
  92         rate = roundup(rate, 2);
  93
  94         /* check if requested speed is too small */
  95         if (rate > 30)
  96                 return -EINVAL;
  97
  98         if (rate < 4)
  99                 rate = 4;
 100
 101         /* Convert the rate to SPI clock divisor value. */
 102         prescale = 0x10 + rate/2;
 103
 104         reg = readl(spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
 105         reg = ((reg & ~ORION_SPI_CLK_PRESCALE_MASK) | prescale);
 106         writel(reg, spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
 107
 108         return 0;
 109 }
 110
 111 static void
 112 orion_spi_mode_set(struct spi_device *spi)
 113 {
 114         u32 reg;
 115         struct orion_spi *orion_spi;
 116
 117         orion_spi = spi_master_get_devdata(spi->master);
 118
 119         reg = readl(spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
 120         reg &= ~ORION_SPI_MODE_MASK;
 121         if (spi->mode & SPI_CPOL)
 122                 reg |= ORION_SPI_MODE_CPOL;
 123         if (spi->mode & SPI_CPHA)
 124                 reg |= ORION_SPI_MODE_CPHA;
 125         writel(reg, spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
 126 }
 127
 128 /*
 129  * called only when no transfer is active on the bus
 130  */
 131 static int
 132 orion_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
 133 {
 134         struct orion_spi *orion_spi;
 135         unsigned int speed = spi->max_speed_hz;
 136         unsigned int bits_per_word = spi->bits_per_word;
 137         int     rc;
 138
 139         orion_spi = spi_master_get_devdata(spi->master);
 140
 141         if ((t != NULL) && t->speed_hz)
 142                 speed = t->speed_hz;
 143
 144         if ((t != NULL) && t->bits_per_word)
 145                 bits_per_word = t->bits_per_word;
 146
 147         orion_spi_mode_set(spi);
 148
 149         rc = orion_spi_baudrate_set(spi, speed);
 150         if (rc)
 151                 return rc;
 152
 153         if (bits_per_word == 16)
 154                 orion_spi_setbits(orion_spi, ORION_SPI_IF_CONFIG_REG,
 155                                   ORION_SPI_IF_8_16_BIT_MODE);
 156         else
 157                 orion_spi_clrbits(orion_spi, ORION_SPI_IF_CONFIG_REG,
 158                                   ORION_SPI_IF_8_16_BIT_MODE);
 159
 160         return 0;
 161 }
 162
 163 static void orion_spi_set_cs(struct orion_spi *orion_spi, int enable)
 164 {
 165         if (enable)
 166                 orion_spi_setbits(orion_spi, ORION_SPI_IF_CTRL_REG, 0x1);
 167         else
 168                 orion_spi_clrbits(orion_spi, ORION_SPI_IF_CTRL_REG, 0x1);
 169 }
 170
 171 static inline int orion_spi_wait_till_ready(struct orion_spi *orion_spi)
 172 {
 173         int i;
 174
 175         for (i = 0; i < ORION_SPI_WAIT_RDY_MAX_LOOP; i++) {
 176                 if (readl(spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG)))
 177                         return 1;
 178                 else
 179                         udelay(1);
 180         }
 181
 182         return -1;
 183 }
 184
 185 static inline int
 186 orion_spi_write_read_8bit(struct spi_device *spi,
 187                           const u8 **tx_buf, u8 **rx_buf)
 188 {
 189         void __iomem *tx_reg, *rx_reg, *int_reg;
 190         struct orion_spi *orion_spi;
 191
 192         orion_spi = spi_master_get_devdata(spi->master);
 193         tx_reg = spi_reg(orion_spi, ORION_SPI_DATA_OUT_REG);
 194         rx_reg = spi_reg(orion_spi, ORION_SPI_DATA_IN_REG);
 195         int_reg = spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG);
 196
 197         /* clear the interrupt cause register */
 198         writel(0x0, int_reg);
 199
 200         if (tx_buf && *tx_buf)
 201                 writel(*(*tx_buf)++, tx_reg);
 202         else
 203                 writel(0, tx_reg);
 204
 205         if (orion_spi_wait_till_ready(orion_spi) < 0) {
 206                 dev_err(&spi->dev, "TXS timed out\n");
 207                 return -1;
 208         }
 209
 210         if (rx_buf && *rx_buf)
 211                 *(*rx_buf)++ = readl(rx_reg);
 212
 213         return 1;
 214 }
 215
 216 static inline int
 217 orion_spi_write_read_16bit(struct spi_device *spi,
 218                            const u16 **tx_buf, u16 **rx_buf)
 219 {
 220         void __iomem *tx_reg, *rx_reg, *int_reg;
 221         struct orion_spi *orion_spi;
 222
 223         orion_spi = spi_master_get_devdata(spi->master);
 224         tx_reg = spi_reg(orion_spi, ORION_SPI_DATA_OUT_REG);
 225         rx_reg = spi_reg(orion_spi, ORION_SPI_DATA_IN_REG);
 226         int_reg = spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG);
 227
 228         /* clear the interrupt cause register */
 229         writel(0x0, int_reg);
 230
 231         if (tx_buf && *tx_buf)
 232                 writel(__cpu_to_le16(get_unaligned((*tx_buf)++)), tx_reg);
 233         else
 234                 writel(0, tx_reg);
 235
 236         if (orion_spi_wait_till_ready(orion_spi) < 0) {
 237                 dev_err(&spi->dev, "TXS timed out\n");
 238                 return -1;
 239         }
 240
 241         if (rx_buf && *rx_buf)
 242                 put_unaligned(__le16_to_cpu(readl(rx_reg)), (*rx_buf)++);
 243
 244         return 1;
 245 }
 246
 247 static unsigned int
 248 orion_spi_write_read(struct spi_device *spi, struct spi_transfer *xfer)
 249 {
 250         unsigned int count;
 251         int word_len;
 252
 253         word_len = spi->bits_per_word;
 254         count = xfer->len;
 255
 256         if (word_len == 8) {
 257                 const u8 *tx = xfer->tx_buf;
 258                 u8 *rx = xfer->rx_buf;
 259
 260                 do {
 261                         if (orion_spi_write_read_8bit(spi, &tx, &rx) < 0)
 262                                 goto out;
 263                         count--;
 264                 } while (count);
 265         } else if (word_len == 16) {
 266                 const u16 *tx = xfer->tx_buf;
 267                 u16 *rx = xfer->rx_buf;
 268
 269                 do {
 270                         if (orion_spi_write_read_16bit(spi, &tx, &rx) < 0)
 271                                 goto out;
 272                         count -= 2;
 273                 } while (count);
 274         }
 275
 276 out:
 277         return xfer->len - count;
 278 }
 279
 280
 281 static int orion_spi_transfer_one_message(struct spi_master *master,
 282                                            struct spi_message *m)
 283 {
 284         struct orion_spi *orion_spi = spi_master_get_devdata(master);
 285         struct spi_device *spi = m->spi;
 286         struct spi_transfer *t = NULL;
 287         int par_override = 0;
 288         int status = 0;
 289         int cs_active = 0;
 290
 291         /* Load defaults */
 292         status = orion_spi_setup_transfer(spi, NULL);
 293
 294         if (status < 0)
 295                 goto msg_done;
 296
 297         list_for_each_entry(t, &m->transfers, transfer_list) {
 298                 if (par_override || t->speed_hz || t->bits_per_word) {
 299                         par_override = 1;
 300                         status = orion_spi_setup_transfer(spi, t);
 301                         if (status < 0)
 302                                 break;
 303                         if (!t->speed_hz && !t->bits_per_word)
 304                                 par_override = 0;
 305                 }
 306
 307                 if (!cs_active) {
 308                         orion_spi_set_cs(orion_spi, 1);
 309                         cs_active = 1;
 310                 }
 311
 312                 if (t->len)
 313                         m->actual_length += orion_spi_write_read(spi, t);
 314
 315                 if (t->delay_usecs)
 316                         udelay(t->delay_usecs);
 317
 318                 if (t->cs_change) {
 319                         orion_spi_set_cs(orion_spi, 0);
 320                         cs_active = 0;
 321                 }
 322         }
 323
 324 msg_done:
 325         if (cs_active)
 326                 orion_spi_set_cs(orion_spi, 0);
 327
 328         m->status = status;
 329         spi_finalize_current_message(master);
 330
 331         return 0;
 332 }
 333
 334 static int orion_spi_reset(struct orion_spi *orion_spi)
 335 {
 336         /* Verify that the CS is deasserted */
 337         orion_spi_set_cs(orion_spi, 0);
 338
 339         return 0;
 340 }
 341
 342 static int orion_spi_probe(struct platform_device *pdev)
 343 {
 344         struct spi_master *master;
 345         struct orion_spi *spi;
 346         struct resource *r;
 347         unsigned long tclk_hz;
 348         int status = 0;
 349
 350         master = spi_alloc_master(&pdev->dev, sizeof(*spi));
 351         if (master == NULL) {
 352                 dev_dbg(&pdev->dev, "master allocation failed\n");
 353                 return -ENOMEM;
 354         }
 355
 356         if (pdev->id != -1)
 357                 master->bus_num = pdev->id;
 358         if (pdev->dev.of_node) {
 359                 u32 cell_index;
 360                 if (!of_property_read_u32(pdev->dev.of_node, "cell-index",
 361                                           &cell_index))
 362                         master->bus_num = cell_index;
 363         }
 364
 365         /* we support only mode 0, and no options */
 366         master->mode_bits = SPI_CPHA | SPI_CPOL;
 367
 368         master->transfer_one_message = orion_spi_transfer_one_message;
 369         master->num_chipselect = ORION_NUM_CHIPSELECTS;
 370         master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
 371
 372         platform_set_drvdata(pdev, master);
 373
 374         spi = spi_master_get_devdata(master);
 375         spi->master = master;
 376
 377         spi->clk = devm_clk_get(&pdev->dev, NULL);
 378         if (IS_ERR(spi->clk)) {
 379                 status = PTR_ERR(spi->clk);
 380                 goto out;
 381         }
 382
 383         clk_prepare(spi->clk);
 384         clk_enable(spi->clk);
 385         tclk_hz = clk_get_rate(spi->clk);
 386         master->max_speed_hz = DIV_ROUND_UP(tclk_hz, 4);
 387         master->min_speed_hz = DIV_ROUND_UP(tclk_hz, 30);
 388
 389         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 390         spi->base = devm_ioremap_resource(&pdev->dev, r);
 391         if (IS_ERR(spi->base)) {
 392                 status = PTR_ERR(spi->base);
 393                 goto out_rel_clk;
 394         }
 395
 396         if (orion_spi_reset(spi) < 0)
 397                 goto out_rel_clk;
 398
 399         master->dev.of_node = pdev->dev.of_node;
 400         status = devm_spi_register_master(&pdev->dev, master);
 401         if (status < 0)
 402                 goto out_rel_clk;
 403
 404         return status;
 405
 406 out_rel_clk:
 407         clk_disable_unprepare(spi->clk);
 408 out:
 409         spi_master_put(master);
 410         return status;
 411 }
 412
 413
 414 static int orion_spi_remove(struct platform_device *pdev)
 415 {
 416         struct spi_master *master;
 417         struct orion_spi *spi;
 418
 419         master = platform_get_drvdata(pdev);
 420         spi = spi_master_get_devdata(master);
 421
 422         clk_disable_unprepare(spi->clk);
 423
 424         return 0;
 425 }
 426
 427 MODULE_ALIAS("platform:" DRIVER_NAME);
 428
 429 static const struct of_device_id orion_spi_of_match_table[] = {
 430         { .compatible = "marvell,orion-spi", },
 431         {}
 432 };
 433 MODULE_DEVICE_TABLE(of, orion_spi_of_match_table);
 434
 435 static struct platform_driver orion_spi_driver = {
 436         .driver = {
 437                 .name   = DRIVER_NAME,
 438                 .owner  = THIS_MODULE,
 439                 .of_match_table = of_match_ptr(orion_spi_of_match_table),
 440         },
 441         .probe          = orion_spi_probe,
 442         .remove         = orion_spi_remove,
 443 };
 444
 445 module_platform_driver(orion_spi_driver);
 446
 447 MODULE_DESCRIPTION("Orion SPI driver");
 448 MODULE_AUTHOR("Shadi Ammouri <shadi@marvell.com>");
 449 MODULE_LICENSE("GPL");