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Linux/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);
405 

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