1 /*
2 * Copyright (C) 2014 Uwe Kleine-Koenig for Pengutronix
3 *
4 * This program is free software; you can redistribute it and/or modify it under
5 * the terms of the GNU General Public License version 2 as published by the
6 * Free Software Foundation.
7 */
8 #include <linux/module.h>
9 #include <linux/platform_device.h>
10 #include <linux/i2c.h>
11 #include <linux/io.h>
12 #include <linux/interrupt.h>
13 #include <linux/err.h>
14 #include <linux/clk.h>
15
16 #define DRIVER_NAME "efm32-i2c"
17
18 #define MASK_VAL(mask, val) ((val << __ffs(mask)) & mask)
19
20 #define REG_CTRL 0x00
21 #define REG_CTRL_EN 0x00001
22 #define REG_CTRL_SLAVE 0x00002
23 #define REG_CTRL_AUTOACK 0x00004
24 #define REG_CTRL_AUTOSE 0x00008
25 #define REG_CTRL_AUTOSN 0x00010
26 #define REG_CTRL_ARBDIS 0x00020
27 #define REG_CTRL_GCAMEN 0x00040
28 #define REG_CTRL_CLHR__MASK 0x00300
29 #define REG_CTRL_BITO__MASK 0x03000
30 #define REG_CTRL_BITO_OFF 0x00000
31 #define REG_CTRL_BITO_40PCC 0x01000
32 #define REG_CTRL_BITO_80PCC 0x02000
33 #define REG_CTRL_BITO_160PCC 0x03000
34 #define REG_CTRL_GIBITO 0x08000
35 #define REG_CTRL_CLTO__MASK 0x70000
36 #define REG_CTRL_CLTO_OFF 0x00000
37
38 #define REG_CMD 0x04
39 #define REG_CMD_START 0x00001
40 #define REG_CMD_STOP 0x00002
41 #define REG_CMD_ACK 0x00004
42 #define REG_CMD_NACK 0x00008
43 #define REG_CMD_CONT 0x00010
44 #define REG_CMD_ABORT 0x00020
45 #define REG_CMD_CLEARTX 0x00040
46 #define REG_CMD_CLEARPC 0x00080
47
48 #define REG_STATE 0x08
49 #define REG_STATE_BUSY 0x00001
50 #define REG_STATE_MASTER 0x00002
51 #define REG_STATE_TRANSMITTER 0x00004
52 #define REG_STATE_NACKED 0x00008
53 #define REG_STATE_BUSHOLD 0x00010
54 #define REG_STATE_STATE__MASK 0x000e0
55 #define REG_STATE_STATE_IDLE 0x00000
56 #define REG_STATE_STATE_WAIT 0x00020
57 #define REG_STATE_STATE_START 0x00040
58 #define REG_STATE_STATE_ADDR 0x00060
59 #define REG_STATE_STATE_ADDRACK 0x00080
60 #define REG_STATE_STATE_DATA 0x000a0
61 #define REG_STATE_STATE_DATAACK 0x000c0
62
63 #define REG_STATUS 0x0c
64 #define REG_STATUS_PSTART 0x00001
65 #define REG_STATUS_PSTOP 0x00002
66 #define REG_STATUS_PACK 0x00004
67 #define REG_STATUS_PNACK 0x00008
68 #define REG_STATUS_PCONT 0x00010
69 #define REG_STATUS_PABORT 0x00020
70 #define REG_STATUS_TXC 0x00040
71 #define REG_STATUS_TXBL 0x00080
72 #define REG_STATUS_RXDATAV 0x00100
73
74 #define REG_CLKDIV 0x10
75 #define REG_CLKDIV_DIV__MASK 0x001ff
76 #define REG_CLKDIV_DIV(div) MASK_VAL(REG_CLKDIV_DIV__MASK, (div))
77
78 #define REG_SADDR 0x14
79 #define REG_SADDRMASK 0x18
80 #define REG_RXDATA 0x1c
81 #define REG_RXDATAP 0x20
82 #define REG_TXDATA 0x24
83 #define REG_IF 0x28
84 #define REG_IF_START 0x00001
85 #define REG_IF_RSTART 0x00002
86 #define REG_IF_ADDR 0x00004
87 #define REG_IF_TXC 0x00008
88 #define REG_IF_TXBL 0x00010
89 #define REG_IF_RXDATAV 0x00020
90 #define REG_IF_ACK 0x00040
91 #define REG_IF_NACK 0x00080
92 #define REG_IF_MSTOP 0x00100
93 #define REG_IF_ARBLOST 0x00200
94 #define REG_IF_BUSERR 0x00400
95 #define REG_IF_BUSHOLD 0x00800
96 #define REG_IF_TXOF 0x01000
97 #define REG_IF_RXUF 0x02000
98 #define REG_IF_BITO 0x04000
99 #define REG_IF_CLTO 0x08000
100 #define REG_IF_SSTOP 0x10000
101
102 #define REG_IFS 0x2c
103 #define REG_IFC 0x30
104 #define REG_IFC__MASK 0x1ffcf
105
106 #define REG_IEN 0x34
107
108 #define REG_ROUTE 0x38
109 #define REG_ROUTE_SDAPEN 0x00001
110 #define REG_ROUTE_SCLPEN 0x00002
111 #define REG_ROUTE_LOCATION__MASK 0x00700
112 #define REG_ROUTE_LOCATION(n) MASK_VAL(REG_ROUTE_LOCATION__MASK, (n))
113
114 struct efm32_i2c_ddata {
115 struct i2c_adapter adapter;
116
117 struct clk *clk;
118 void __iomem *base;
119 unsigned int irq;
120 u8 location;
121 unsigned long frequency;
122
123 /* transfer data */
124 struct completion done;
125 struct i2c_msg *msgs;
126 size_t num_msgs;
127 size_t current_word, current_msg;
128 int retval;
129 };
130
efm32_i2c_read32(struct efm32_i2c_ddata * ddata,unsigned offset)131 static u32 efm32_i2c_read32(struct efm32_i2c_ddata *ddata, unsigned offset)
132 {
133 return readl(ddata->base + offset);
134 }
135
efm32_i2c_write32(struct efm32_i2c_ddata * ddata,unsigned offset,u32 value)136 static void efm32_i2c_write32(struct efm32_i2c_ddata *ddata,
137 unsigned offset, u32 value)
138 {
139 writel(value, ddata->base + offset);
140 }
141
efm32_i2c_send_next_msg(struct efm32_i2c_ddata * ddata)142 static void efm32_i2c_send_next_msg(struct efm32_i2c_ddata *ddata)
143 {
144 struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
145
146 efm32_i2c_write32(ddata, REG_CMD, REG_CMD_START);
147 efm32_i2c_write32(ddata, REG_TXDATA, cur_msg->addr << 1 |
148 (cur_msg->flags & I2C_M_RD ? 1 : 0));
149 }
150
efm32_i2c_send_next_byte(struct efm32_i2c_ddata * ddata)151 static void efm32_i2c_send_next_byte(struct efm32_i2c_ddata *ddata)
152 {
153 struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
154
155 if (ddata->current_word >= cur_msg->len) {
156 /* cur_msg completely transferred */
157 ddata->current_word = 0;
158 ddata->current_msg += 1;
159
160 if (ddata->current_msg >= ddata->num_msgs) {
161 efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
162 complete(&ddata->done);
163 } else {
164 efm32_i2c_send_next_msg(ddata);
165 }
166 } else {
167 efm32_i2c_write32(ddata, REG_TXDATA,
168 cur_msg->buf[ddata->current_word++]);
169 }
170 }
171
efm32_i2c_recv_next_byte(struct efm32_i2c_ddata * ddata)172 static void efm32_i2c_recv_next_byte(struct efm32_i2c_ddata *ddata)
173 {
174 struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
175
176 cur_msg->buf[ddata->current_word] = efm32_i2c_read32(ddata, REG_RXDATA);
177 ddata->current_word += 1;
178 if (ddata->current_word >= cur_msg->len) {
179 /* cur_msg completely transferred */
180 ddata->current_word = 0;
181 ddata->current_msg += 1;
182
183 efm32_i2c_write32(ddata, REG_CMD, REG_CMD_NACK);
184
185 if (ddata->current_msg >= ddata->num_msgs) {
186 efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
187 complete(&ddata->done);
188 } else {
189 efm32_i2c_send_next_msg(ddata);
190 }
191 } else {
192 efm32_i2c_write32(ddata, REG_CMD, REG_CMD_ACK);
193 }
194 }
195
efm32_i2c_irq(int irq,void * dev_id)196 static irqreturn_t efm32_i2c_irq(int irq, void *dev_id)
197 {
198 struct efm32_i2c_ddata *ddata = dev_id;
199 struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
200 u32 irqflag = efm32_i2c_read32(ddata, REG_IF);
201 u32 state = efm32_i2c_read32(ddata, REG_STATE);
202
203 efm32_i2c_write32(ddata, REG_IFC, irqflag & REG_IFC__MASK);
204
205 switch (state & REG_STATE_STATE__MASK) {
206 case REG_STATE_STATE_IDLE:
207 /* arbitration lost? */
208 ddata->retval = -EAGAIN;
209 complete(&ddata->done);
210 break;
211 case REG_STATE_STATE_WAIT:
212 /*
213 * huh, this shouldn't happen.
214 * Reset hardware state and get out
215 */
216 ddata->retval = -EIO;
217 efm32_i2c_write32(ddata, REG_CMD,
218 REG_CMD_STOP | REG_CMD_ABORT |
219 REG_CMD_CLEARTX | REG_CMD_CLEARPC);
220 complete(&ddata->done);
221 break;
222 case REG_STATE_STATE_START:
223 /* "caller" is expected to send an address */
224 break;
225 case REG_STATE_STATE_ADDR:
226 /* wait for Ack or NAck of slave */
227 break;
228 case REG_STATE_STATE_ADDRACK:
229 if (state & REG_STATE_NACKED) {
230 efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
231 ddata->retval = -ENXIO;
232 complete(&ddata->done);
233 } else if (cur_msg->flags & I2C_M_RD) {
234 /* wait for slave to send first data byte */
235 } else {
236 efm32_i2c_send_next_byte(ddata);
237 }
238 break;
239 case REG_STATE_STATE_DATA:
240 if (cur_msg->flags & I2C_M_RD) {
241 efm32_i2c_recv_next_byte(ddata);
242 } else {
243 /* wait for Ack or Nack of slave */
244 }
245 break;
246 case REG_STATE_STATE_DATAACK:
247 if (state & REG_STATE_NACKED) {
248 efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
249 complete(&ddata->done);
250 } else {
251 efm32_i2c_send_next_byte(ddata);
252 }
253 }
254
255 return IRQ_HANDLED;
256 }
257
efm32_i2c_master_xfer(struct i2c_adapter * adap,struct i2c_msg * msgs,int num)258 static int efm32_i2c_master_xfer(struct i2c_adapter *adap,
259 struct i2c_msg *msgs, int num)
260 {
261 struct efm32_i2c_ddata *ddata = i2c_get_adapdata(adap);
262 int ret;
263
264 if (ddata->msgs)
265 return -EBUSY;
266
267 ddata->msgs = msgs;
268 ddata->num_msgs = num;
269 ddata->current_word = 0;
270 ddata->current_msg = 0;
271 ddata->retval = -EIO;
272
273 reinit_completion(&ddata->done);
274
275 dev_dbg(&ddata->adapter.dev, "state: %08x, status: %08x\n",
276 efm32_i2c_read32(ddata, REG_STATE),
277 efm32_i2c_read32(ddata, REG_STATUS));
278
279 efm32_i2c_send_next_msg(ddata);
280
281 wait_for_completion(&ddata->done);
282
283 if (ddata->current_msg >= ddata->num_msgs)
284 ret = ddata->num_msgs;
285 else
286 ret = ddata->retval;
287
288 return ret;
289 }
290
efm32_i2c_functionality(struct i2c_adapter * adap)291 static u32 efm32_i2c_functionality(struct i2c_adapter *adap)
292 {
293 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
294 }
295
296 static const struct i2c_algorithm efm32_i2c_algo = {
297 .master_xfer = efm32_i2c_master_xfer,
298 .functionality = efm32_i2c_functionality,
299 };
300
efm32_i2c_get_configured_location(struct efm32_i2c_ddata * ddata)301 static u32 efm32_i2c_get_configured_location(struct efm32_i2c_ddata *ddata)
302 {
303 u32 reg = efm32_i2c_read32(ddata, REG_ROUTE);
304
305 return (reg & REG_ROUTE_LOCATION__MASK) >>
306 __ffs(REG_ROUTE_LOCATION__MASK);
307 }
308
efm32_i2c_probe(struct platform_device * pdev)309 static int efm32_i2c_probe(struct platform_device *pdev)
310 {
311 struct efm32_i2c_ddata *ddata;
312 struct resource *res;
313 unsigned long rate;
314 struct device_node *np = pdev->dev.of_node;
315 u32 location, frequency;
316 int ret;
317 u32 clkdiv;
318
319 if (!np)
320 return -EINVAL;
321
322 ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
323 if (!ddata)
324 return -ENOMEM;
325 platform_set_drvdata(pdev, ddata);
326
327 init_completion(&ddata->done);
328 strlcpy(ddata->adapter.name, pdev->name, sizeof(ddata->adapter.name));
329 ddata->adapter.owner = THIS_MODULE;
330 ddata->adapter.algo = &efm32_i2c_algo;
331 ddata->adapter.dev.parent = &pdev->dev;
332 ddata->adapter.dev.of_node = pdev->dev.of_node;
333 i2c_set_adapdata(&ddata->adapter, ddata);
334
335 ddata->clk = devm_clk_get(&pdev->dev, NULL);
336 if (IS_ERR(ddata->clk)) {
337 ret = PTR_ERR(ddata->clk);
338 dev_err(&pdev->dev, "failed to get clock: %d\n", ret);
339 return ret;
340 }
341
342 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
343 if (!res) {
344 dev_err(&pdev->dev, "failed to determine base address\n");
345 return -ENODEV;
346 }
347
348 if (resource_size(res) < 0x42) {
349 dev_err(&pdev->dev, "memory resource too small\n");
350 return -EINVAL;
351 }
352
353 ddata->base = devm_ioremap_resource(&pdev->dev, res);
354 if (IS_ERR(ddata->base))
355 return PTR_ERR(ddata->base);
356
357 ret = platform_get_irq(pdev, 0);
358 if (ret <= 0) {
359 dev_err(&pdev->dev, "failed to get irq (%d)\n", ret);
360 if (!ret)
361 ret = -EINVAL;
362 return ret;
363 }
364
365 ddata->irq = ret;
366
367 ret = clk_prepare_enable(ddata->clk);
368 if (ret < 0) {
369 dev_err(&pdev->dev, "failed to enable clock (%d)\n", ret);
370 return ret;
371 }
372
373
374 ret = of_property_read_u32(np, "energymicro,location", &location);
375
376 if (ret)
377 /* fall back to wrongly namespaced property */
378 ret = of_property_read_u32(np, "efm32,location", &location);
379
380 if (!ret) {
381 dev_dbg(&pdev->dev, "using location %u\n", location);
382 } else {
383 /* default to location configured in hardware */
384 location = efm32_i2c_get_configured_location(ddata);
385
386 dev_info(&pdev->dev, "fall back to location %u\n", location);
387 }
388
389 ddata->location = location;
390
391 ret = of_property_read_u32(np, "clock-frequency", &frequency);
392 if (!ret) {
393 dev_dbg(&pdev->dev, "using frequency %u\n", frequency);
394 } else {
395 frequency = 100000;
396 dev_info(&pdev->dev, "defaulting to 100 kHz\n");
397 }
398 ddata->frequency = frequency;
399
400 rate = clk_get_rate(ddata->clk);
401 if (!rate) {
402 dev_err(&pdev->dev, "there is no input clock available\n");
403 ret = -EINVAL;
404 goto err_disable_clk;
405 }
406 clkdiv = DIV_ROUND_UP(rate, 8 * ddata->frequency) - 1;
407 if (clkdiv >= 0x200) {
408 dev_err(&pdev->dev,
409 "input clock too fast (%lu) to divide down to bus freq (%lu)",
410 rate, ddata->frequency);
411 ret = -EINVAL;
412 goto err_disable_clk;
413 }
414
415 dev_dbg(&pdev->dev, "input clock = %lu, bus freq = %lu, clkdiv = %lu\n",
416 rate, ddata->frequency, (unsigned long)clkdiv);
417 efm32_i2c_write32(ddata, REG_CLKDIV, REG_CLKDIV_DIV(clkdiv));
418
419 efm32_i2c_write32(ddata, REG_ROUTE, REG_ROUTE_SDAPEN |
420 REG_ROUTE_SCLPEN |
421 REG_ROUTE_LOCATION(ddata->location));
422
423 efm32_i2c_write32(ddata, REG_CTRL, REG_CTRL_EN |
424 REG_CTRL_BITO_160PCC | 0 * REG_CTRL_GIBITO);
425
426 efm32_i2c_write32(ddata, REG_IFC, REG_IFC__MASK);
427 efm32_i2c_write32(ddata, REG_IEN, REG_IF_TXC | REG_IF_ACK | REG_IF_NACK
428 | REG_IF_ARBLOST | REG_IF_BUSERR | REG_IF_RXDATAV);
429
430 /* to make bus idle */
431 efm32_i2c_write32(ddata, REG_CMD, REG_CMD_ABORT);
432
433 ret = request_irq(ddata->irq, efm32_i2c_irq, 0, DRIVER_NAME, ddata);
434 if (ret < 0) {
435 dev_err(&pdev->dev, "failed to request irq (%d)\n", ret);
436 return ret;
437 }
438
439 ret = i2c_add_adapter(&ddata->adapter);
440 if (ret) {
441 dev_err(&pdev->dev, "failed to add i2c adapter (%d)\n", ret);
442 free_irq(ddata->irq, ddata);
443
444 err_disable_clk:
445 clk_disable_unprepare(ddata->clk);
446 }
447 return ret;
448 }
449
efm32_i2c_remove(struct platform_device * pdev)450 static int efm32_i2c_remove(struct platform_device *pdev)
451 {
452 struct efm32_i2c_ddata *ddata = platform_get_drvdata(pdev);
453
454 i2c_del_adapter(&ddata->adapter);
455 free_irq(ddata->irq, ddata);
456 clk_disable_unprepare(ddata->clk);
457
458 return 0;
459 }
460
461 static const struct of_device_id efm32_i2c_dt_ids[] = {
462 {
463 .compatible = "energymicro,efm32-i2c",
464 }, {
465 /* sentinel */
466 }
467 };
468 MODULE_DEVICE_TABLE(of, efm32_i2c_dt_ids);
469
470 static struct platform_driver efm32_i2c_driver = {
471 .probe = efm32_i2c_probe,
472 .remove = efm32_i2c_remove,
473
474 .driver = {
475 .name = DRIVER_NAME,
476 .owner = THIS_MODULE,
477 .of_match_table = efm32_i2c_dt_ids,
478 },
479 };
480 module_platform_driver(efm32_i2c_driver);
481
482 MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>");
483 MODULE_DESCRIPTION("EFM32 i2c driver");
484 MODULE_LICENSE("GPL v2");
485 MODULE_ALIAS("platform:" DRIVER_NAME);
486