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Masahiro Yamadadd6fd4a2015-10-23 19:51:59 +09001/*
2 * Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 */
14
15#include <linux/clk.h>
16#include <linux/i2c.h>
17#include <linux/interrupt.h>
18#include <linux/io.h>
19#include <linux/module.h>
20#include <linux/platform_device.h>
21
22#define UNIPHIER_I2C_DTRM 0x00 /* TX register */
23#define UNIPHIER_I2C_DTRM_IRQEN BIT(11) /* enable interrupt */
24#define UNIPHIER_I2C_DTRM_STA BIT(10) /* start condition */
25#define UNIPHIER_I2C_DTRM_STO BIT(9) /* stop condition */
26#define UNIPHIER_I2C_DTRM_NACK BIT(8) /* do not return ACK */
27#define UNIPHIER_I2C_DTRM_RD BIT(0) /* read transaction */
28#define UNIPHIER_I2C_DREC 0x04 /* RX register */
29#define UNIPHIER_I2C_DREC_MST BIT(14) /* 1 = master, 0 = slave */
30#define UNIPHIER_I2C_DREC_TX BIT(13) /* 1 = transmit, 0 = receive */
31#define UNIPHIER_I2C_DREC_STS BIT(12) /* stop condition detected */
32#define UNIPHIER_I2C_DREC_LRB BIT(11) /* no ACK */
33#define UNIPHIER_I2C_DREC_LAB BIT(9) /* arbitration lost */
34#define UNIPHIER_I2C_DREC_BBN BIT(8) /* bus not busy */
35#define UNIPHIER_I2C_MYAD 0x08 /* slave address */
36#define UNIPHIER_I2C_CLK 0x0c /* clock frequency control */
37#define UNIPHIER_I2C_BRST 0x10 /* bus reset */
38#define UNIPHIER_I2C_BRST_FOEN BIT(1) /* normal operation */
39#define UNIPHIER_I2C_BRST_RSCL BIT(0) /* release SCL */
40#define UNIPHIER_I2C_HOLD 0x14 /* hold time control */
41#define UNIPHIER_I2C_BSTS 0x18 /* bus status monitor */
42#define UNIPHIER_I2C_BSTS_SDA BIT(1) /* readback of SDA line */
43#define UNIPHIER_I2C_BSTS_SCL BIT(0) /* readback of SCL line */
44#define UNIPHIER_I2C_NOISE 0x1c /* noise filter control */
45#define UNIPHIER_I2C_SETUP 0x20 /* setup time control */
46
47#define UNIPHIER_I2C_DEFAULT_SPEED 100000
48#define UNIPHIER_I2C_MAX_SPEED 400000
49
50struct uniphier_i2c_priv {
51 struct completion comp;
52 struct i2c_adapter adap;
53 void __iomem *membase;
54 struct clk *clk;
55 unsigned int busy_cnt;
56};
57
58static irqreturn_t uniphier_i2c_interrupt(int irq, void *dev_id)
59{
60 struct uniphier_i2c_priv *priv = dev_id;
61
62 /*
63 * This hardware uses edge triggered interrupt. Do not touch the
64 * hardware registers in this handler to make sure to catch the next
65 * interrupt edge. Just send a complete signal and return.
66 */
67 complete(&priv->comp);
68
69 return IRQ_HANDLED;
70}
71
72static int uniphier_i2c_xfer_byte(struct i2c_adapter *adap, u32 txdata,
73 u32 *rxdatap)
74{
75 struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
76 unsigned long time_left;
77 u32 rxdata;
78
79 reinit_completion(&priv->comp);
80
81 txdata |= UNIPHIER_I2C_DTRM_IRQEN;
82 dev_dbg(&adap->dev, "write data: 0x%04x\n", txdata);
83 writel(txdata, priv->membase + UNIPHIER_I2C_DTRM);
84
85 time_left = wait_for_completion_timeout(&priv->comp, adap->timeout);
86 if (unlikely(!time_left)) {
87 dev_err(&adap->dev, "transaction timeout\n");
88 return -ETIMEDOUT;
89 }
90
91 rxdata = readl(priv->membase + UNIPHIER_I2C_DREC);
92 dev_dbg(&adap->dev, "read data: 0x%04x\n", rxdata);
93
94 if (rxdatap)
95 *rxdatap = rxdata;
96
97 return 0;
98}
99
100static int uniphier_i2c_send_byte(struct i2c_adapter *adap, u32 txdata)
101{
102 u32 rxdata;
103 int ret;
104
105 ret = uniphier_i2c_xfer_byte(adap, txdata, &rxdata);
106 if (ret)
107 return ret;
108
109 if (unlikely(rxdata & UNIPHIER_I2C_DREC_LAB)) {
110 dev_dbg(&adap->dev, "arbitration lost\n");
111 return -EAGAIN;
112 }
113 if (unlikely(rxdata & UNIPHIER_I2C_DREC_LRB)) {
114 dev_dbg(&adap->dev, "could not get ACK\n");
115 return -ENXIO;
116 }
117
118 return 0;
119}
120
121static int uniphier_i2c_tx(struct i2c_adapter *adap, u16 addr, u16 len,
122 const u8 *buf)
123{
124 int ret;
125
126 dev_dbg(&adap->dev, "start condition\n");
127 ret = uniphier_i2c_send_byte(adap, addr << 1 |
128 UNIPHIER_I2C_DTRM_STA |
129 UNIPHIER_I2C_DTRM_NACK);
130 if (ret)
131 return ret;
132
133 while (len--) {
134 ret = uniphier_i2c_send_byte(adap,
135 UNIPHIER_I2C_DTRM_NACK | *buf++);
136 if (ret)
137 return ret;
138 }
139
140 return 0;
141}
142
143static int uniphier_i2c_rx(struct i2c_adapter *adap, u16 addr, u16 len,
144 u8 *buf)
145{
146 int ret;
147
148 dev_dbg(&adap->dev, "start condition\n");
149 ret = uniphier_i2c_send_byte(adap, addr << 1 |
150 UNIPHIER_I2C_DTRM_STA |
151 UNIPHIER_I2C_DTRM_NACK |
152 UNIPHIER_I2C_DTRM_RD);
153 if (ret)
154 return ret;
155
156 while (len--) {
157 u32 rxdata;
158
159 ret = uniphier_i2c_xfer_byte(adap,
160 len ? 0 : UNIPHIER_I2C_DTRM_NACK,
161 &rxdata);
162 if (ret)
163 return ret;
164 *buf++ = rxdata;
165 }
166
167 return 0;
168}
169
170static int uniphier_i2c_stop(struct i2c_adapter *adap)
171{
172 dev_dbg(&adap->dev, "stop condition\n");
173 return uniphier_i2c_send_byte(adap, UNIPHIER_I2C_DTRM_STO |
174 UNIPHIER_I2C_DTRM_NACK);
175}
176
177static int uniphier_i2c_master_xfer_one(struct i2c_adapter *adap,
178 struct i2c_msg *msg, bool stop)
179{
180 bool is_read = msg->flags & I2C_M_RD;
181 bool recovery = false;
182 int ret;
183
184 dev_dbg(&adap->dev, "%s: addr=0x%02x, len=%d, stop=%d\n",
185 is_read ? "receive" : "transmit", msg->addr, msg->len, stop);
186
187 if (is_read)
188 ret = uniphier_i2c_rx(adap, msg->addr, msg->len, msg->buf);
189 else
190 ret = uniphier_i2c_tx(adap, msg->addr, msg->len, msg->buf);
191
192 if (ret == -EAGAIN) /* could not acquire bus. bail out without STOP */
193 return ret;
194
195 if (ret == -ETIMEDOUT) {
196 /* This error is fatal. Needs recovery. */
197 stop = false;
198 recovery = true;
199 }
200
201 if (stop) {
202 int ret2 = uniphier_i2c_stop(adap);
203
204 if (ret2) {
205 /* Failed to issue STOP. The bus needs recovery. */
206 recovery = true;
207 ret = ret ?: ret2;
208 }
209 }
210
211 if (recovery)
212 i2c_recover_bus(adap);
213
214 return ret;
215}
216
217static int uniphier_i2c_check_bus_busy(struct i2c_adapter *adap)
218{
219 struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
220
221 if (!(readl(priv->membase + UNIPHIER_I2C_DREC) &
222 UNIPHIER_I2C_DREC_BBN)) {
223 if (priv->busy_cnt++ > 3) {
224 /*
225 * If bus busy continues too long, it is probably
226 * in a wrong state. Try bus recovery.
227 */
228 i2c_recover_bus(adap);
229 priv->busy_cnt = 0;
230 }
231
232 return -EAGAIN;
233 }
234
235 priv->busy_cnt = 0;
236 return 0;
237}
238
239static int uniphier_i2c_master_xfer(struct i2c_adapter *adap,
240 struct i2c_msg *msgs, int num)
241{
242 struct i2c_msg *msg, *emsg = msgs + num;
243 int ret;
244
245 ret = uniphier_i2c_check_bus_busy(adap);
246 if (ret)
247 return ret;
248
249 for (msg = msgs; msg < emsg; msg++) {
250 /* If next message is read, skip the stop condition */
251 bool stop = !(msg + 1 < emsg && msg[1].flags & I2C_M_RD);
252 /* but, force it if I2C_M_STOP is set */
253 if (msg->flags & I2C_M_STOP)
254 stop = true;
255
256 ret = uniphier_i2c_master_xfer_one(adap, msg, stop);
257 if (ret)
258 return ret;
259 }
260
261 return num;
262}
263
264static u32 uniphier_i2c_functionality(struct i2c_adapter *adap)
265{
266 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
267}
268
269static const struct i2c_algorithm uniphier_i2c_algo = {
270 .master_xfer = uniphier_i2c_master_xfer,
271 .functionality = uniphier_i2c_functionality,
272};
273
274static void uniphier_i2c_reset(struct uniphier_i2c_priv *priv, bool reset_on)
275{
276 u32 val = UNIPHIER_I2C_BRST_RSCL;
277
278 val |= reset_on ? 0 : UNIPHIER_I2C_BRST_FOEN;
279 writel(val, priv->membase + UNIPHIER_I2C_BRST);
280}
281
282static int uniphier_i2c_get_scl(struct i2c_adapter *adap)
283{
284 struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
285
286 return !!(readl(priv->membase + UNIPHIER_I2C_BSTS) &
287 UNIPHIER_I2C_BSTS_SCL);
288}
289
290static void uniphier_i2c_set_scl(struct i2c_adapter *adap, int val)
291{
292 struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
293
294 writel(val ? UNIPHIER_I2C_BRST_RSCL : 0,
295 priv->membase + UNIPHIER_I2C_BRST);
296}
297
298static int uniphier_i2c_get_sda(struct i2c_adapter *adap)
299{
300 struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
301
302 return !!(readl(priv->membase + UNIPHIER_I2C_BSTS) &
303 UNIPHIER_I2C_BSTS_SDA);
304}
305
306static void uniphier_i2c_unprepare_recovery(struct i2c_adapter *adap)
307{
308 uniphier_i2c_reset(i2c_get_adapdata(adap), false);
309}
310
311static struct i2c_bus_recovery_info uniphier_i2c_bus_recovery_info = {
312 .recover_bus = i2c_generic_scl_recovery,
313 .get_scl = uniphier_i2c_get_scl,
314 .set_scl = uniphier_i2c_set_scl,
315 .get_sda = uniphier_i2c_get_sda,
316 .unprepare_recovery = uniphier_i2c_unprepare_recovery,
317};
318
319static int uniphier_i2c_clk_init(struct device *dev,
320 struct uniphier_i2c_priv *priv)
321{
322 struct device_node *np = dev->of_node;
323 unsigned long clk_rate;
324 u32 bus_speed;
325 int ret;
326
327 if (of_property_read_u32(np, "clock-frequency", &bus_speed))
328 bus_speed = UNIPHIER_I2C_DEFAULT_SPEED;
329
Masahiro Yamada2d5d23b2015-11-30 18:53:34 +0900330 if (!bus_speed) {
Masahiro Yamadabca71ba2016-01-26 18:09:21 +0900331 dev_err(dev, "clock-frequency should not be zero\n");
Masahiro Yamada2d5d23b2015-11-30 18:53:34 +0900332 return -EINVAL;
333 }
334
Masahiro Yamadadd6fd4a2015-10-23 19:51:59 +0900335 if (bus_speed > UNIPHIER_I2C_MAX_SPEED)
336 bus_speed = UNIPHIER_I2C_MAX_SPEED;
337
338 /* Get input clk rate through clk driver */
339 priv->clk = devm_clk_get(dev, NULL);
340 if (IS_ERR(priv->clk)) {
341 dev_err(dev, "failed to get clock\n");
342 return PTR_ERR(priv->clk);
343 }
344
345 ret = clk_prepare_enable(priv->clk);
346 if (ret)
347 return ret;
348
349 clk_rate = clk_get_rate(priv->clk);
Masahiro Yamada1ff49b32015-11-30 18:53:33 +0900350 if (!clk_rate) {
351 dev_err(dev, "input clock rate should not be zero\n");
352 return -EINVAL;
353 }
Masahiro Yamadadd6fd4a2015-10-23 19:51:59 +0900354
355 uniphier_i2c_reset(priv, true);
356
357 writel((clk_rate / bus_speed / 2 << 16) | (clk_rate / bus_speed),
358 priv->membase + UNIPHIER_I2C_CLK);
359
360 uniphier_i2c_reset(priv, false);
361
362 return 0;
363}
364
365static int uniphier_i2c_probe(struct platform_device *pdev)
366{
367 struct device *dev = &pdev->dev;
368 struct uniphier_i2c_priv *priv;
369 struct resource *regs;
370 int irq;
371 int ret;
372
373 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
374 if (!priv)
375 return -ENOMEM;
376
377 regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
378 priv->membase = devm_ioremap_resource(dev, regs);
379 if (IS_ERR(priv->membase))
380 return PTR_ERR(priv->membase);
381
382 irq = platform_get_irq(pdev, 0);
383 if (irq < 0) {
Masahiro Yamada8a350182016-04-21 15:12:44 +0900384 dev_err(dev, "failed to get IRQ number\n");
Masahiro Yamadadd6fd4a2015-10-23 19:51:59 +0900385 return irq;
386 }
387
388 init_completion(&priv->comp);
389 priv->adap.owner = THIS_MODULE;
390 priv->adap.algo = &uniphier_i2c_algo;
391 priv->adap.dev.parent = dev;
392 priv->adap.dev.of_node = dev->of_node;
393 strlcpy(priv->adap.name, "UniPhier I2C", sizeof(priv->adap.name));
394 priv->adap.bus_recovery_info = &uniphier_i2c_bus_recovery_info;
395 i2c_set_adapdata(&priv->adap, priv);
396 platform_set_drvdata(pdev, priv);
397
398 ret = uniphier_i2c_clk_init(dev, priv);
399 if (ret)
Masahiro Yamada1ff49b32015-11-30 18:53:33 +0900400 goto err;
Masahiro Yamadadd6fd4a2015-10-23 19:51:59 +0900401
402 ret = devm_request_irq(dev, irq, uniphier_i2c_interrupt, 0, pdev->name,
403 priv);
404 if (ret) {
405 dev_err(dev, "failed to request irq %d\n", irq);
406 goto err;
407 }
408
409 ret = i2c_add_adapter(&priv->adap);
410 if (ret) {
411 dev_err(dev, "failed to add I2C adapter\n");
412 goto err;
413 }
414
415err:
416 if (ret)
417 clk_disable_unprepare(priv->clk);
418
419 return ret;
420}
421
422static int uniphier_i2c_remove(struct platform_device *pdev)
423{
424 struct uniphier_i2c_priv *priv = platform_get_drvdata(pdev);
425
426 i2c_del_adapter(&priv->adap);
427 clk_disable_unprepare(priv->clk);
428
429 return 0;
430}
431
432static const struct of_device_id uniphier_i2c_match[] = {
433 { .compatible = "socionext,uniphier-i2c" },
434 { /* sentinel */ }
435};
436MODULE_DEVICE_TABLE(of, uniphier_i2c_match);
437
438static struct platform_driver uniphier_i2c_drv = {
439 .probe = uniphier_i2c_probe,
440 .remove = uniphier_i2c_remove,
441 .driver = {
442 .name = "uniphier-i2c",
443 .of_match_table = uniphier_i2c_match,
444 },
445};
446module_platform_driver(uniphier_i2c_drv);
447
448MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
449MODULE_DESCRIPTION("UniPhier I2C bus driver");
450MODULE_LICENSE("GPL");