linux/drivers/i2c/busses/i2c-s6000.c
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   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
  47struct 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
  65static inline u16 i2c_rd16(struct s6i2c_if *iface, unsigned n)
  66{
  67        return readw(iface->reg + (n));
  68}
  69
  70static inline void i2c_wr16(struct s6i2c_if *iface, unsigned n, u16 v)
  71{
  72        writew(v, iface->reg + (n));
  73}
  74
  75static inline u32 i2c_rd32(struct s6i2c_if *iface, unsigned n)
  76{
  77        return readl(iface->reg + (n));
  78}
  79
  80static inline void i2c_wr32(struct s6i2c_if *iface, unsigned n, u32 v)
  81{
  82        writel(v, iface->reg + (n));
  83}
  84
  85static struct s6i2c_if s6i2c_if;
  86
  87static 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
 145static 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
 169static 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
 186static 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
 241static u32 s6i2c_functionality(struct i2c_adapter *adap)
 242{
 243        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 244}
 245
 246static struct i2c_algorithm s6i2c_algorithm = {
 247        .master_xfer   = s6i2c_master_xfer,
 248        .functionality = s6i2c_functionality,
 249};
 250
 251static 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
 259static 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->dev.platform_data) {
 294                struct s6_i2c_platform_data *pdata = dev->dev.platform_data;
 295                bus_num = pdata->bus_num;
 296                clock = pdata->clock;
 297        }
 298        iface->clk = clk_get(&dev->dev, clock);
 299        if (IS_ERR(iface->clk)) {
 300                rc = PTR_ERR(iface->clk);
 301                goto err_map;
 302        }
 303        rc = clk_enable(iface->clk);
 304        if (rc < 0)
 305                goto err_clk_put;
 306        init_timer(&iface->timeout_timer);
 307        iface->timeout_timer.function = s6i2c_timeout;
 308        iface->timeout_timer.data = (unsigned long)iface;
 309
 310        p_adap = &iface->adap;
 311        strlcpy(p_adap->name, dev->name, sizeof(p_adap->name));
 312        p_adap->algo = &s6i2c_algorithm;
 313        p_adap->algo_data = iface;
 314        p_adap->nr = bus_num;
 315        p_adap->class = 0;
 316        p_adap->dev.parent = &dev->dev;
 317        i2c_wr16(iface, S6_I2C_INTRMASK, 0);
 318        rc = request_irq(iface->irq, s6i2c_interrupt_entry,
 319                         IRQF_SHARED, dev->name, iface);
 320        if (rc) {
 321                dev_err(&p_adap->dev, "s6i2c: can't get IRQ %d\n", iface->irq);
 322                goto err_clk_dis;
 323        }
 324
 325        i2c_wr16(iface, S6_I2C_ENABLE, 0);
 326        udelay(1);
 327        i2c_wr32(iface, S6_I2C_SRESET, 1 << S6_I2C_SRESET_IC_SRST);
 328        i2c_wr16(iface, S6_I2C_CLRTXABRT, 1);
 329        i2c_wr16(iface, S6_I2C_CON,
 330                        (1 << S6_I2C_CON_MASTER) |
 331                        (S6_I2C_CON_SPEED_NORMAL << S6_I2C_CON_SPEED) |
 332                        (0 << S6_I2C_CON_10BITSLAVE) |
 333                        (0 << S6_I2C_CON_10BITMASTER) |
 334                        (1 << S6_I2C_CON_RESTARTENA) |
 335                        (1 << S6_I2C_CON_SLAVEDISABLE));
 336        i2c_wr16(iface, S6_I2C_SSHCNT, nanoseconds_on_clk(iface, 4000));
 337        i2c_wr16(iface, S6_I2C_SSLCNT, nanoseconds_on_clk(iface, 4700));
 338        i2c_wr16(iface, S6_I2C_FSHCNT, nanoseconds_on_clk(iface, 600));
 339        i2c_wr16(iface, S6_I2C_FSLCNT, nanoseconds_on_clk(iface, 1300));
 340        i2c_wr16(iface, S6_I2C_RXTL, 0);
 341        i2c_wr16(iface, S6_I2C_TXTL, 0);
 342
 343        platform_set_drvdata(dev, iface);
 344        rc = i2c_add_numbered_adapter(p_adap);
 345        if (rc)
 346                goto err_irq_free;
 347        return 0;
 348
 349err_irq_free:
 350        free_irq(iface->irq, iface);
 351err_clk_dis:
 352        clk_disable(iface->clk);
 353err_clk_put:
 354        clk_put(iface->clk);
 355err_map:
 356        iounmap(iface->reg);
 357err_reg:
 358        release_mem_region(iface->res->start,
 359                           resource_size(iface->res));
 360err_out:
 361        return rc;
 362}
 363
 364static int s6i2c_remove(struct platform_device *pdev)
 365{
 366        struct s6i2c_if *iface = platform_get_drvdata(pdev);
 367        i2c_wr16(iface, S6_I2C_ENABLE, 0);
 368        i2c_del_adapter(&iface->adap);
 369        free_irq(iface->irq, iface);
 370        clk_disable(iface->clk);
 371        clk_put(iface->clk);
 372        iounmap(iface->reg);
 373        release_mem_region(iface->res->start,
 374                           resource_size(iface->res));
 375        return 0;
 376}
 377
 378static struct platform_driver s6i2c_driver = {
 379        .probe          = s6i2c_probe,
 380        .remove         = s6i2c_remove,
 381        .driver         = {
 382                .name   = DRV_NAME,
 383                .owner  = THIS_MODULE,
 384        },
 385};
 386
 387static int __init s6i2c_init(void)
 388{
 389        pr_info("I2C: S6000 I2C driver\n");
 390        return platform_driver_register(&s6i2c_driver);
 391}
 392
 393static void __exit s6i2c_exit(void)
 394{
 395        platform_driver_unregister(&s6i2c_driver);
 396}
 397
 398MODULE_DESCRIPTION("I2C-Bus adapter routines for S6000 I2C");
 399MODULE_LICENSE("GPL");
 400MODULE_ALIAS("platform:" DRV_NAME);
 401
 402subsys_initcall(s6i2c_init);
 403module_exit(s6i2c_exit);
 404