[PATCH] i2c-ocores: Minor cleanups
[linux-2.6.git] / drivers / i2c / busses / i2c-ocores.c
1 /*
2  * i2c-ocores.c: I2C bus driver for OpenCores I2C controller
3  * (http://www.opencores.org/projects.cgi/web/i2c/overview).
4  *
5  * Peter Korsgaard <jacmet@sunsite.dk>
6  *
7  * This file is licensed under the terms of the GNU General Public License
8  * version 2.  This program is licensed "as is" without any warranty of any
9  * kind, whether express or implied.
10  */
11
12 #include <linux/config.h>
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/sched.h>
16 #include <linux/init.h>
17 #include <linux/errno.h>
18 #include <linux/platform_device.h>
19 #include <linux/i2c.h>
20 #include <linux/interrupt.h>
21 #include <linux/wait.h>
22 #include <linux/i2c-ocores.h>
23 #include <asm/io.h>
24
25 struct ocores_i2c {
26         void __iomem *base;
27         int regstep;
28         wait_queue_head_t wait;
29         struct i2c_adapter adap;
30         struct i2c_msg *msg;
31         int pos;
32         int nmsgs;
33         int state; /* see STATE_ */
34 };
35
36 /* registers */
37 #define OCI2C_PRELOW            0
38 #define OCI2C_PREHIGH           1
39 #define OCI2C_CONTROL           2
40 #define OCI2C_DATA              3
41 #define OCI2C_CMD               4 /* write only */
42 #define OCI2C_STATUS            4 /* read only, same address as OCI2C_CMD */
43
44 #define OCI2C_CTRL_IEN          0x40
45 #define OCI2C_CTRL_EN           0x80
46
47 #define OCI2C_CMD_START         0x91
48 #define OCI2C_CMD_STOP          0x41
49 #define OCI2C_CMD_READ          0x21
50 #define OCI2C_CMD_WRITE         0x11
51 #define OCI2C_CMD_READ_ACK      0x21
52 #define OCI2C_CMD_READ_NACK     0x29
53 #define OCI2C_CMD_IACK          0x01
54
55 #define OCI2C_STAT_IF           0x01
56 #define OCI2C_STAT_TIP          0x02
57 #define OCI2C_STAT_ARBLOST      0x20
58 #define OCI2C_STAT_BUSY         0x40
59 #define OCI2C_STAT_NACK         0x80
60
61 #define STATE_DONE              0
62 #define STATE_START             1
63 #define STATE_WRITE             2
64 #define STATE_READ              3
65 #define STATE_ERROR             4
66
67 static inline void oc_setreg(struct ocores_i2c *i2c, int reg, u8 value)
68 {
69         iowrite8(value, i2c->base + reg * i2c->regstep);
70 }
71
72 static inline u8 oc_getreg(struct ocores_i2c *i2c, int reg)
73 {
74         return ioread8(i2c->base + reg * i2c->regstep);
75 }
76
77 static void ocores_process(struct ocores_i2c *i2c)
78 {
79         struct i2c_msg *msg = i2c->msg;
80         u8 stat = oc_getreg(i2c, OCI2C_STATUS);
81
82         if ((i2c->state == STATE_DONE) || (i2c->state == STATE_ERROR)) {
83                 /* stop has been sent */
84                 oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK);
85                 wake_up(&i2c->wait);
86                 return;
87         }
88
89         /* error? */
90         if (stat & OCI2C_STAT_ARBLOST) {
91                 i2c->state = STATE_ERROR;
92                 oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
93                 return;
94         }
95
96         if ((i2c->state == STATE_START) || (i2c->state == STATE_WRITE)) {
97                 i2c->state =
98                         (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
99
100                 if (stat & OCI2C_STAT_NACK) {
101                         i2c->state = STATE_ERROR;
102                         oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
103                         return;
104                 }
105         } else
106                 msg->buf[i2c->pos++] = oc_getreg(i2c, OCI2C_DATA);
107
108         /* end of msg? */
109         if (i2c->pos == msg->len) {
110                 i2c->nmsgs--;
111                 i2c->msg++;
112                 i2c->pos = 0;
113                 msg = i2c->msg;
114
115                 if (i2c->nmsgs) {       /* end? */
116                         /* send start? */
117                         if (!(msg->flags & I2C_M_NOSTART)) {
118                                 u8 addr = (msg->addr << 1);
119
120                                 if (msg->flags & I2C_M_RD)
121                                         addr |= 1;
122
123                                 i2c->state = STATE_START;
124
125                                 oc_setreg(i2c, OCI2C_DATA, addr);
126                                 oc_setreg(i2c, OCI2C_CMD,  OCI2C_CMD_START);
127                                 return;
128                         } else
129                                 i2c->state = (msg->flags & I2C_M_RD)
130                                         ? STATE_READ : STATE_WRITE;
131                 } else {
132                         i2c->state = STATE_DONE;
133                         oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
134                         return;
135                 }
136         }
137
138         if (i2c->state == STATE_READ) {
139                 oc_setreg(i2c, OCI2C_CMD, i2c->pos == (msg->len-1) ?
140                           OCI2C_CMD_READ_NACK : OCI2C_CMD_READ_ACK);
141         } else {
142                 oc_setreg(i2c, OCI2C_DATA, msg->buf[i2c->pos++]);
143                 oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_WRITE);
144         }
145 }
146
147 static irqreturn_t ocores_isr(int irq, void *dev_id, struct pt_regs *regs)
148 {
149         struct ocores_i2c *i2c = dev_id;
150
151         ocores_process(i2c);
152
153         return IRQ_HANDLED;
154 }
155
156 static int ocores_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
157 {
158         struct ocores_i2c *i2c = i2c_get_adapdata(adap);
159
160         i2c->msg = msgs;
161         i2c->pos = 0;
162         i2c->nmsgs = num;
163         i2c->state = STATE_START;
164
165         oc_setreg(i2c, OCI2C_DATA,
166                         (i2c->msg->addr << 1) |
167                         ((i2c->msg->flags & I2C_M_RD) ? 1:0));
168
169         oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START);
170
171         if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) ||
172                                (i2c->state == STATE_DONE), HZ))
173                 return (i2c->state == STATE_DONE) ? num : -EIO;
174         else
175                 return -ETIMEDOUT;
176 }
177
178 static void ocores_init(struct ocores_i2c *i2c,
179                         struct ocores_i2c_platform_data *pdata)
180 {
181         int prescale;
182         u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL);
183
184         /* make sure the device is disabled */
185         oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
186
187         prescale = (pdata->clock_khz / (5*100)) - 1;
188         oc_setreg(i2c, OCI2C_PRELOW, prescale & 0xff);
189         oc_setreg(i2c, OCI2C_PREHIGH, prescale >> 8);
190
191         /* Init the device */
192         oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK);
193         oc_setreg(i2c, OCI2C_CONTROL, ctrl | OCI2C_CTRL_IEN | OCI2C_CTRL_EN);
194 }
195
196
197 static u32 ocores_func(struct i2c_adapter *adap)
198 {
199         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
200 }
201
202 static struct i2c_algorithm ocores_algorithm = {
203         .master_xfer    = ocores_xfer,
204         .functionality  = ocores_func,
205 };
206
207 static struct i2c_adapter ocores_adapter = {
208         .owner          = THIS_MODULE,
209         .name           = "i2c-ocores",
210         .class          = I2C_CLASS_HWMON,
211         .algo           = &ocores_algorithm,
212 };
213
214
215 static int __devinit ocores_i2c_probe(struct platform_device *pdev)
216 {
217         struct ocores_i2c *i2c;
218         struct ocores_i2c_platform_data *pdata;
219         struct resource *res, *res2;
220         int ret;
221
222         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
223         if (!res)
224                 return -ENODEV;
225
226         res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
227         if (!res2)
228                 return -ENODEV;
229
230         pdata = (struct ocores_i2c_platform_data*) pdev->dev.platform_data;
231         if (!pdata)
232                 return -ENODEV;
233
234         i2c = kzalloc(sizeof(*i2c), GFP_KERNEL);
235         if (!i2c)
236                 return -ENOMEM;
237
238         if (!request_mem_region(res->start, res->end - res->start + 1,
239                                 pdev->name)) {
240                 dev_err(&pdev->dev, "Memory region busy\n");
241                 ret = -EBUSY;
242                 goto request_mem_failed;
243         }
244
245         i2c->base = ioremap(res->start, res->end - res->start + 1);
246         if (!i2c->base) {
247                 dev_err(&pdev->dev, "Unable to map registers\n");
248                 ret = -EIO;
249                 goto map_failed;
250         }
251
252         i2c->regstep = pdata->regstep;
253         ocores_init(i2c, pdata);
254
255         init_waitqueue_head(&i2c->wait);
256         ret = request_irq(res2->start, ocores_isr, 0, pdev->name, i2c);
257         if (ret) {
258                 dev_err(&pdev->dev, "Cannot claim IRQ\n");
259                 goto request_irq_failed;
260         }
261
262         /* hook up driver to tree */
263         platform_set_drvdata(pdev, i2c);
264         i2c->adap = ocores_adapter;
265         i2c_set_adapdata(&i2c->adap, i2c);
266         i2c->adap.dev.parent = &pdev->dev;
267
268         /* add i2c adapter to i2c tree */
269         ret = i2c_add_adapter(&i2c->adap);
270         if (ret) {
271                 dev_err(&pdev->dev, "Failed to add adapter\n");
272                 goto add_adapter_failed;
273         }
274
275         return 0;
276
277 add_adapter_failed:
278         free_irq(res2->start, i2c);
279 request_irq_failed:
280         iounmap(i2c->base);
281 map_failed:
282         release_mem_region(res->start, res->end - res->start + 1);
283 request_mem_failed:
284         kfree(i2c);
285
286         return ret;
287 }
288
289 static int __devexit ocores_i2c_remove(struct platform_device* pdev)
290 {
291         struct ocores_i2c *i2c = platform_get_drvdata(pdev);
292         struct resource *res;
293
294         /* disable i2c logic */
295         oc_setreg(i2c, OCI2C_CONTROL, oc_getreg(i2c, OCI2C_CONTROL)
296                   & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
297
298         /* remove adapter & data */
299         i2c_del_adapter(&i2c->adap);
300         platform_set_drvdata(pdev, NULL);
301
302         res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
303         if (res)
304                 free_irq(res->start, i2c);
305
306         iounmap(i2c->base);
307
308         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
309         if (res)
310                 release_mem_region(res->start, res->end - res->start + 1);
311
312         kfree(i2c);
313
314         return 0;
315 }
316
317 static struct platform_driver ocores_i2c_driver = {
318         .probe  = ocores_i2c_probe,
319         .remove = __devexit_p(ocores_i2c_remove),
320         .driver = {
321                 .owner = THIS_MODULE,
322                 .name = "ocores-i2c",
323         },
324 };
325
326 static int __init ocores_i2c_init(void)
327 {
328         return platform_driver_register(&ocores_i2c_driver);
329 }
330
331 static void __exit ocores_i2c_exit(void)
332 {
333         platform_driver_unregister(&ocores_i2c_driver);
334 }
335
336 module_init(ocores_i2c_init);
337 module_exit(ocores_i2c_exit);
338
339 MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
340 MODULE_DESCRIPTION("OpenCores I2C bus driver");
341 MODULE_LICENSE("GPL");