drivers/i2c/busses/i2c-s6000.c

   1 /*
   2  * drivers/i2c/busses/i2c-s6000.c
   3  *
   4  * Description: Driver for S6000 Family I2C Interface
   5  * Copyright (c) 2008 emlix GmbH
   6  * Author:      Oskar Schirmer <oskar@scara.com>
   7  *
   8  * Partially based on i2c-bfin-twi.c driver by <sonic.zhang@analog.com>
   9  * Copyright (c) 2005-2007 Analog Devices, Inc.
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA
  24  */
  25
  26 #include <linux/clk.h>
  27 #include <linux/err.h>
  28 #include <linux/module.h>
  29 #include <linux/kernel.h>
  30 #include <linux/init.h>
  31 #include <linux/delay.h>
  32 #include <linux/i2c.h>
  33 #include <linux/i2c/s6000.h>
  34 #include <linux/timer.h>
  35 #include <linux/spinlock.h>
  36 #include <linux/completion.h>
  37 #include <linux/interrupt.h>
  38 #include <linux/platform_device.h>
  39 #include <linux/io.h>
  40
  41 #include "i2c-s6000.h"
  42
  43 #define DRV_NAME "i2c-s6000"
  44
  45 #define POLL_TIMEOUT    (2 * HZ)
  46
  47 struct s6i2c_if {
  48         u8 __iomem              *reg; /* memory mapped registers */
  49         int                     irq;
  50         spinlock_t              lock;
  51         struct i2c_msg          *msgs; /* messages currently handled */
  52         int                     msgs_num; /* nb of msgs to do */
  53         int                     msgs_push; /* nb of msgs read/written */
  54         int                     msgs_done; /* nb of msgs finally handled */
  55         unsigned                push; /* nb of bytes read/written in msg */
  56         unsigned                done; /* nb of bytes finally handled */
  57         int                     timeout_count; /* timeout retries left */
  58         struct timer_list       timeout_timer;
  59         struct i2c_adapter      adap;
  60         struct completion       complete;
  61         struct clk              *clk;
  62         struct resource         *res;
  63 };
  64
  65 static inline u16 i2c_rd16(struct s6i2c_if *iface, unsigned n)
  66 {
  67         return readw(iface->reg + (n));
  68 }
  69
  70 static inline void i2c_wr16(struct s6i2c_if *iface, unsigned n, u16 v)
  71 {
  72         writew(v, iface->reg + (n));
  73 }
  74
  75 static inline u32 i2c_rd32(struct s6i2c_if *iface, unsigned n)
  76 {
  77         return readl(iface->reg + (n));
  78 }
  79
  80 static inline void i2c_wr32(struct s6i2c_if *iface, unsigned n, u32 v)
  81 {
  82         writel(v, iface->reg + (n));
  83 }
  84
  85 static struct s6i2c_if s6i2c_if;
  86
  87 static void s6i2c_handle_interrupt(struct s6i2c_if *iface)
  88 {
  89         if (i2c_rd16(iface, S6_I2C_INTRSTAT) & (1 << S6_I2C_INTR_TXABRT)) {
  90                 i2c_rd16(iface, S6_I2C_CLRTXABRT);
  91                 i2c_wr16(iface, S6_I2C_INTRMASK, 0);
  92                 complete(&iface->complete);
  93                 return;
  94         }
  95         if (iface->msgs_done >= iface->msgs_num) {
  96                 dev_err(&iface->adap.dev, "s6i2c: spurious I2C irq: %04x\n",
  97                         i2c_rd16(iface, S6_I2C_INTRSTAT));
  98                 i2c_wr16(iface, S6_I2C_INTRMASK, 0);
  99                 return;
 100         }
 101         while ((iface->msgs_push < iface->msgs_num)
 102             && (i2c_rd16(iface, S6_I2C_STATUS) & (1 << S6_I2C_STATUS_TFNF))) {
 103                 struct i2c_msg *m = &iface->msgs[iface->msgs_push];
 104                 if (!(m->flags & I2C_M_RD))
 105                         i2c_wr16(iface, S6_I2C_DATACMD, m->buf[iface->push]);
 106                 else
 107                         i2c_wr16(iface, S6_I2C_DATACMD,
 108                                  1 << S6_I2C_DATACMD_READ);
 109                 if (++iface->push >= m->len) {
 110                         iface->push = 0;
 111                         iface->msgs_push += 1;
 112                 }
 113         }
 114         do {
 115                 struct i2c_msg *m = &iface->msgs[iface->msgs_done];
 116                 if (!(m->flags & I2C_M_RD)) {
 117                         if (iface->msgs_done < iface->msgs_push)
 118                                 iface->msgs_done += 1;
 119                         else
 120                                 break;
 121                 } else if (i2c_rd16(iface, S6_I2C_STATUS)
 122                                 & (1 << S6_I2C_STATUS_RFNE)) {
 123                         m->buf[iface->done] = i2c_rd16(iface, S6_I2C_DATACMD);
 124                         if (++iface->done >= m->len) {
 125                                 iface->done = 0;
 126                                 iface->msgs_done += 1;
 127                         }
 128                 } else{
 129                         break;
 130                 }
 131         } while (iface->msgs_done < iface->msgs_num);
 132         if (iface->msgs_done >= iface->msgs_num) {
 133                 i2c_wr16(iface, S6_I2C_INTRMASK, 1 << S6_I2C_INTR_TXABRT);
 134                 complete(&iface->complete);
 135         } else if (iface->msgs_push >= iface->msgs_num) {
 136                 i2c_wr16(iface, S6_I2C_INTRMASK, (1 << S6_I2C_INTR_TXABRT) |
 137                                                  (1 << S6_I2C_INTR_RXFULL));
 138         } else {
 139                 i2c_wr16(iface, S6_I2C_INTRMASK, (1 << S6_I2C_INTR_TXABRT) |
 140                                                  (1 << S6_I2C_INTR_TXEMPTY) |
 141                                                  (1 << S6_I2C_INTR_RXFULL));
 142         }
 143 }
 144
 145 static irqreturn_t s6i2c_interrupt_entry(int irq, void *dev_id)
 146 {
 147         struct s6i2c_if *iface = dev_id;
 148         if (!(i2c_rd16(iface, S6_I2C_STATUS) & ((1 << S6_I2C_INTR_RXUNDER)
 149                                               | (1 << S6_I2C_INTR_RXOVER)
 150                                               | (1 << S6_I2C_INTR_RXFULL)
 151                                               | (1 << S6_I2C_INTR_TXOVER)
 152                                               | (1 << S6_I2C_INTR_TXEMPTY)
 153                                               | (1 << S6_I2C_INTR_RDREQ)
 154                                               | (1 << S6_I2C_INTR_TXABRT)
 155                                               | (1 << S6_I2C_INTR_RXDONE)
 156                                               | (1 << S6_I2C_INTR_ACTIVITY)
 157                                               | (1 << S6_I2C_INTR_STOPDET)
 158                                               | (1 << S6_I2C_INTR_STARTDET)
 159                                               | (1 << S6_I2C_INTR_GENCALL))))
 160                 return IRQ_NONE;
 161
 162         spin_lock(&iface->lock);
 163         del_timer(&iface->timeout_timer);
 164         s6i2c_handle_interrupt(iface);
 165         spin_unlock(&iface->lock);
 166         return IRQ_HANDLED;
 167 }
 168
 169 static void s6i2c_timeout(unsigned long data)
 170 {
 171         struct s6i2c_if *iface = (struct s6i2c_if *)data;
 172         unsigned long flags;
 173
 174         spin_lock_irqsave(&iface->lock, flags);
 175         s6i2c_handle_interrupt(iface);
 176         if (--iface->timeout_count > 0) {
 177                 iface->timeout_timer.expires = jiffies + POLL_TIMEOUT;
 178                 add_timer(&iface->timeout_timer);
 179         } else {
 180                 complete(&iface->complete);
 181                 i2c_wr16(iface, S6_I2C_INTRMASK, 0);
 182         }
 183         spin_unlock_irqrestore(&iface->lock, flags);
 184 }
 185
 186 static int s6i2c_master_xfer(struct i2c_adapter *adap,
 187                                 struct i2c_msg *msgs, int num)
 188 {
 189         struct s6i2c_if *iface = adap->algo_data;
 190         int i;
 191         if (num == 0)
 192                 return 0;
 193         if (i2c_rd16(iface, S6_I2C_STATUS) & (1 << S6_I2C_STATUS_ACTIVITY))
 194                 yield();
 195         i2c_wr16(iface, S6_I2C_INTRMASK, 0);
 196         i2c_rd16(iface, S6_I2C_CLRINTR);
 197         for (i = 0; i < num; i++) {
 198                 if (msgs[i].flags & I2C_M_TEN) {
 199                         dev_err(&adap->dev,
 200                                 "s6i2c: 10 bits addr not supported\n");
 201                         return -EINVAL;
 202                 }
 203                 if (msgs[i].len == 0) {
 204                         dev_err(&adap->dev,
 205                                 "s6i2c: zero length message not supported\n");
 206                         return -EINVAL;
 207                 }
 208                 if (msgs[i].addr != msgs[0].addr) {
 209                         dev_err(&adap->dev,
 210                                 "s6i2c: multiple xfer cannot change target\n");
 211                         return -EINVAL;
 212                 }
 213         }
 214
 215         iface->msgs = msgs;
 216         iface->msgs_num = num;
 217         iface->msgs_push = 0;
 218         iface->msgs_done = 0;
 219         iface->push = 0;
 220         iface->done = 0;
 221         iface->timeout_count = 10;
 222         i2c_wr16(iface, S6_I2C_TAR, msgs[0].addr);
 223         i2c_wr16(iface, S6_I2C_ENABLE, 1);
 224         i2c_wr16(iface, S6_I2C_INTRMASK, (1 << S6_I2C_INTR_TXEMPTY) |
 225                                          (1 << S6_I2C_INTR_TXABRT));
 226
 227         iface->timeout_timer.expires = jiffies + POLL_TIMEOUT;
 228         add_timer(&iface->timeout_timer);
 229         wait_for_completion(&iface->complete);
 230         del_timer_sync(&iface->timeout_timer);
 231         while (i2c_rd32(iface, S6_I2C_TXFLR) > 0)
 232                 schedule();
 233         while (i2c_rd16(iface, S6_I2C_STATUS) & (1 << S6_I2C_STATUS_ACTIVITY))
 234                 schedule();
 235
 236         i2c_wr16(iface, S6_I2C_INTRMASK, 0);
 237         i2c_wr16(iface, S6_I2C_ENABLE, 0);
 238         return iface->msgs_done;
 239 }
 240
 241 static u32 s6i2c_functionality(struct i2c_adapter *adap)
 242 {
 243         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 244 }
 245
 246 static struct i2c_algorithm s6i2c_algorithm = {
 247         .master_xfer   = s6i2c_master_xfer,
 248         .functionality = s6i2c_functionality,
 249 };
 250
 251 static u16 nanoseconds_on_clk(struct s6i2c_if *iface, u32 ns)
 252 {
 253         u32 dividend = ((clk_get_rate(iface->clk) / 1000) * ns) / 1000000;
 254         if (dividend > 0xffff)
 255                 return 0xffff;
 256         return dividend;
 257 }
 258
 259 static int s6i2c_probe(struct platform_device *dev)
 260 {
 261         struct s6i2c_if *iface = &s6i2c_if;
 262         struct i2c_adapter *p_adap;
 263         const char *clock;
 264         int bus_num, rc;
 265         spin_lock_init(&iface->lock);
 266         init_completion(&iface->complete);
 267         iface->irq = platform_get_irq(dev, 0);
 268         if (iface->irq < 0) {
 269                 rc = iface->irq;
 270                 goto err_out;
 271         }
 272         iface->res = platform_get_resource(dev, IORESOURCE_MEM, 0);
 273         if (!iface->res) {
 274                 rc = -ENXIO;
 275                 goto err_out;
 276         }
 277         iface->res = request_mem_region(iface->res->start,
 278                                         resource_size(iface->res),
 279                                         dev->dev.bus_id);
 280         if (!iface->res) {
 281                 rc = -EBUSY;
 282                 goto err_out;
 283         }
 284         iface->reg = ioremap_nocache(iface->res->start,
 285                                      resource_size(iface->res));
 286         if (!iface->reg) {
 287                 rc = -ENOMEM;
 288                 goto err_reg;
 289         }
 290
 291         clock = 0;
 292         bus_num = -1;
 293         if (dev_get_platdata(&dev->dev)) {
 294                 struct s6_i2c_platform_data *pdata =
 295                         dev_get_platdata(&dev->dev);
 296                 bus_num = pdata->bus_num;
 297                 clock = pdata->clock;
 298         }
 299         iface->clk = clk_get(&dev->dev, clock);
 300         if (IS_ERR(iface->clk)) {
 301                 rc = PTR_ERR(iface->clk);
 302                 goto err_map;
 303         }
 304         rc = clk_enable(iface->clk);
 305         if (rc < 0)
 306                 goto err_clk_put;
 307         init_timer(&iface->timeout_timer);
 308         iface->timeout_timer.function = s6i2c_timeout;
 309         iface->timeout_timer.data = (unsigned long)iface;
 310
 311         p_adap = &iface->adap;
 312         strlcpy(p_adap->name, dev->name, sizeof(p_adap->name));
 313         p_adap->algo = &s6i2c_algorithm;
 314         p_adap->algo_data = iface;
 315         p_adap->nr = bus_num;
 316         p_adap->class = 0;
 317         p_adap->dev.parent = &dev->dev;
 318         i2c_wr16(iface, S6_I2C_INTRMASK, 0);
 319         rc = request_irq(iface->irq, s6i2c_interrupt_entry,
 320                          IRQF_SHARED, dev->name, iface);
 321         if (rc) {
 322                 dev_err(&p_adap->dev, "s6i2c: can't get IRQ %d\n", iface->irq);
 323                 goto err_clk_dis;
 324         }
 325
 326         i2c_wr16(iface, S6_I2C_ENABLE, 0);
 327         udelay(1);
 328         i2c_wr32(iface, S6_I2C_SRESET, 1 << S6_I2C_SRESET_IC_SRST);
 329         i2c_wr16(iface, S6_I2C_CLRTXABRT, 1);
 330         i2c_wr16(iface, S6_I2C_CON,
 331                         (1 << S6_I2C_CON_MASTER) |
 332                         (S6_I2C_CON_SPEED_NORMAL << S6_I2C_CON_SPEED) |
 333                         (0 << S6_I2C_CON_10BITSLAVE) |
 334                         (0 << S6_I2C_CON_10BITMASTER) |
 335                         (1 << S6_I2C_CON_RESTARTENA) |
 336                         (1 << S6_I2C_CON_SLAVEDISABLE));
 337         i2c_wr16(iface, S6_I2C_SSHCNT, nanoseconds_on_clk(iface, 4000));
 338         i2c_wr16(iface, S6_I2C_SSLCNT, nanoseconds_on_clk(iface, 4700));
 339         i2c_wr16(iface, S6_I2C_FSHCNT, nanoseconds_on_clk(iface, 600));
 340         i2c_wr16(iface, S6_I2C_FSLCNT, nanoseconds_on_clk(iface, 1300));
 341         i2c_wr16(iface, S6_I2C_RXTL, 0);
 342         i2c_wr16(iface, S6_I2C_TXTL, 0);
 343
 344         platform_set_drvdata(dev, iface);
 345         rc = i2c_add_numbered_adapter(p_adap);
 346         if (rc)
 347                 goto err_irq_free;
 348         return 0;
 349
 350 err_irq_free:
 351         free_irq(iface->irq, iface);
 352 err_clk_dis:
 353         clk_disable(iface->clk);
 354 err_clk_put:
 355         clk_put(iface->clk);
 356 err_map:
 357         iounmap(iface->reg);
 358 err_reg:
 359         release_mem_region(iface->res->start,
 360                            resource_size(iface->res));
 361 err_out:
 362         return rc;
 363 }
 364
 365 static int s6i2c_remove(struct platform_device *pdev)
 366 {
 367         struct s6i2c_if *iface = platform_get_drvdata(pdev);
 368         i2c_wr16(iface, S6_I2C_ENABLE, 0);
 369         i2c_del_adapter(&iface->adap);
 370         free_irq(iface->irq, iface);
 371         clk_disable(iface->clk);
 372         clk_put(iface->clk);
 373         iounmap(iface->reg);
 374         release_mem_region(iface->res->start,
 375                            resource_size(iface->res));
 376         return 0;
 377 }
 378
 379 static struct platform_driver s6i2c_driver = {
 380         .probe          = s6i2c_probe,
 381         .remove         = s6i2c_remove,
 382         .driver         = {
 383                 .name   = DRV_NAME,
 384                 .owner  = THIS_MODULE,
 385         },
 386 };
 387
 388 static int __init s6i2c_init(void)
 389 {
 390         pr_info("I2C: S6000 I2C driver\n");
 391         return platform_driver_register(&s6i2c_driver);
 392 }
 393
 394 static void __exit s6i2c_exit(void)
 395 {
 396         platform_driver_unregister(&s6i2c_driver);
 397 }
 398
 399 MODULE_DESCRIPTION("I2C-Bus adapter routines for S6000 I2C");
 400 MODULE_LICENSE("GPL");
 401 MODULE_ALIAS("platform:" DRV_NAME);
 402
 403 subsys_initcall(s6i2c_init);
 404 module_exit(s6i2c_exit);