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6#include <linux/clk.h>
7#include <linux/i2c.h>
8#include <linux/interrupt.h>
9#include <linux/io.h>
10#include <linux/module.h>
11#include <linux/platform_device.h>
12
13#define UNIPHIER_I2C_DTRM 0x00
14#define UNIPHIER_I2C_DTRM_IRQEN BIT(11)
15#define UNIPHIER_I2C_DTRM_STA BIT(10)
16#define UNIPHIER_I2C_DTRM_STO BIT(9)
17#define UNIPHIER_I2C_DTRM_NACK BIT(8)
18#define UNIPHIER_I2C_DTRM_RD BIT(0)
19#define UNIPHIER_I2C_DREC 0x04
20#define UNIPHIER_I2C_DREC_MST BIT(14)
21#define UNIPHIER_I2C_DREC_TX BIT(13)
22#define UNIPHIER_I2C_DREC_STS BIT(12)
23#define UNIPHIER_I2C_DREC_LRB BIT(11)
24#define UNIPHIER_I2C_DREC_LAB BIT(9)
25#define UNIPHIER_I2C_DREC_BBN BIT(8)
26#define UNIPHIER_I2C_MYAD 0x08
27#define UNIPHIER_I2C_CLK 0x0c
28#define UNIPHIER_I2C_BRST 0x10
29#define UNIPHIER_I2C_BRST_FOEN BIT(1)
30#define UNIPHIER_I2C_BRST_RSCL BIT(0)
31#define UNIPHIER_I2C_HOLD 0x14
32#define UNIPHIER_I2C_BSTS 0x18
33#define UNIPHIER_I2C_BSTS_SDA BIT(1)
34#define UNIPHIER_I2C_BSTS_SCL BIT(0)
35#define UNIPHIER_I2C_NOISE 0x1c
36#define UNIPHIER_I2C_SETUP 0x20
37
38#define UNIPHIER_I2C_DEFAULT_SPEED 100000
39#define UNIPHIER_I2C_MAX_SPEED 400000
40
41struct uniphier_i2c_priv {
42 struct completion comp;
43 struct i2c_adapter adap;
44 void __iomem *membase;
45 struct clk *clk;
46 unsigned int busy_cnt;
47 unsigned int clk_cycle;
48};
49
50static irqreturn_t uniphier_i2c_interrupt(int irq, void *dev_id)
51{
52 struct uniphier_i2c_priv *priv = dev_id;
53
54
55
56
57
58
59 complete(&priv->comp);
60
61 return IRQ_HANDLED;
62}
63
64static int uniphier_i2c_xfer_byte(struct i2c_adapter *adap, u32 txdata,
65 u32 *rxdatap)
66{
67 struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
68 unsigned long time_left;
69 u32 rxdata;
70
71 reinit_completion(&priv->comp);
72
73 txdata |= UNIPHIER_I2C_DTRM_IRQEN;
74 writel(txdata, priv->membase + UNIPHIER_I2C_DTRM);
75
76 time_left = wait_for_completion_timeout(&priv->comp, adap->timeout);
77 if (unlikely(!time_left)) {
78 dev_err(&adap->dev, "transaction timeout\n");
79 return -ETIMEDOUT;
80 }
81
82 rxdata = readl(priv->membase + UNIPHIER_I2C_DREC);
83 if (rxdatap)
84 *rxdatap = rxdata;
85
86 return 0;
87}
88
89static int uniphier_i2c_send_byte(struct i2c_adapter *adap, u32 txdata)
90{
91 u32 rxdata;
92 int ret;
93
94 ret = uniphier_i2c_xfer_byte(adap, txdata, &rxdata);
95 if (ret)
96 return ret;
97
98 if (unlikely(rxdata & UNIPHIER_I2C_DREC_LAB))
99 return -EAGAIN;
100
101 if (unlikely(rxdata & UNIPHIER_I2C_DREC_LRB))
102 return -ENXIO;
103
104 return 0;
105}
106
107static int uniphier_i2c_tx(struct i2c_adapter *adap, u16 addr, u16 len,
108 const u8 *buf)
109{
110 int ret;
111
112 ret = uniphier_i2c_send_byte(adap, addr << 1 |
113 UNIPHIER_I2C_DTRM_STA |
114 UNIPHIER_I2C_DTRM_NACK);
115 if (ret)
116 return ret;
117
118 while (len--) {
119 ret = uniphier_i2c_send_byte(adap,
120 UNIPHIER_I2C_DTRM_NACK | *buf++);
121 if (ret)
122 return ret;
123 }
124
125 return 0;
126}
127
128static int uniphier_i2c_rx(struct i2c_adapter *adap, u16 addr, u16 len,
129 u8 *buf)
130{
131 int ret;
132
133 ret = uniphier_i2c_send_byte(adap, addr << 1 |
134 UNIPHIER_I2C_DTRM_STA |
135 UNIPHIER_I2C_DTRM_NACK |
136 UNIPHIER_I2C_DTRM_RD);
137 if (ret)
138 return ret;
139
140 while (len--) {
141 u32 rxdata;
142
143 ret = uniphier_i2c_xfer_byte(adap,
144 len ? 0 : UNIPHIER_I2C_DTRM_NACK,
145 &rxdata);
146 if (ret)
147 return ret;
148 *buf++ = rxdata;
149 }
150
151 return 0;
152}
153
154static int uniphier_i2c_stop(struct i2c_adapter *adap)
155{
156 return uniphier_i2c_send_byte(adap, UNIPHIER_I2C_DTRM_STO |
157 UNIPHIER_I2C_DTRM_NACK);
158}
159
160static int uniphier_i2c_master_xfer_one(struct i2c_adapter *adap,
161 struct i2c_msg *msg, bool stop)
162{
163 bool is_read = msg->flags & I2C_M_RD;
164 bool recovery = false;
165 int ret;
166
167 if (is_read)
168 ret = uniphier_i2c_rx(adap, msg->addr, msg->len, msg->buf);
169 else
170 ret = uniphier_i2c_tx(adap, msg->addr, msg->len, msg->buf);
171
172 if (ret == -EAGAIN)
173 return ret;
174
175 if (ret == -ETIMEDOUT) {
176
177 stop = false;
178 recovery = true;
179 }
180
181 if (stop) {
182 int ret2 = uniphier_i2c_stop(adap);
183
184 if (ret2) {
185
186 recovery = true;
187 ret = ret ?: ret2;
188 }
189 }
190
191 if (recovery)
192 i2c_recover_bus(adap);
193
194 return ret;
195}
196
197static int uniphier_i2c_check_bus_busy(struct i2c_adapter *adap)
198{
199 struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
200
201 if (!(readl(priv->membase + UNIPHIER_I2C_DREC) &
202 UNIPHIER_I2C_DREC_BBN)) {
203 if (priv->busy_cnt++ > 3) {
204
205
206
207
208 i2c_recover_bus(adap);
209 priv->busy_cnt = 0;
210 }
211
212 return -EAGAIN;
213 }
214
215 priv->busy_cnt = 0;
216 return 0;
217}
218
219static int uniphier_i2c_master_xfer(struct i2c_adapter *adap,
220 struct i2c_msg *msgs, int num)
221{
222 struct i2c_msg *msg, *emsg = msgs + num;
223 int ret;
224
225 ret = uniphier_i2c_check_bus_busy(adap);
226 if (ret)
227 return ret;
228
229 for (msg = msgs; msg < emsg; msg++) {
230
231 bool stop = (msg + 1 == emsg) || (msg->flags & I2C_M_STOP);
232
233 ret = uniphier_i2c_master_xfer_one(adap, msg, stop);
234 if (ret)
235 return ret;
236 }
237
238 return num;
239}
240
241static u32 uniphier_i2c_functionality(struct i2c_adapter *adap)
242{
243 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
244}
245
246static const struct i2c_algorithm uniphier_i2c_algo = {
247 .master_xfer = uniphier_i2c_master_xfer,
248 .functionality = uniphier_i2c_functionality,
249};
250
251static void uniphier_i2c_reset(struct uniphier_i2c_priv *priv, bool reset_on)
252{
253 u32 val = UNIPHIER_I2C_BRST_RSCL;
254
255 val |= reset_on ? 0 : UNIPHIER_I2C_BRST_FOEN;
256 writel(val, priv->membase + UNIPHIER_I2C_BRST);
257}
258
259static int uniphier_i2c_get_scl(struct i2c_adapter *adap)
260{
261 struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
262
263 return !!(readl(priv->membase + UNIPHIER_I2C_BSTS) &
264 UNIPHIER_I2C_BSTS_SCL);
265}
266
267static void uniphier_i2c_set_scl(struct i2c_adapter *adap, int val)
268{
269 struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
270
271 writel(val ? UNIPHIER_I2C_BRST_RSCL : 0,
272 priv->membase + UNIPHIER_I2C_BRST);
273}
274
275static int uniphier_i2c_get_sda(struct i2c_adapter *adap)
276{
277 struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
278
279 return !!(readl(priv->membase + UNIPHIER_I2C_BSTS) &
280 UNIPHIER_I2C_BSTS_SDA);
281}
282
283static void uniphier_i2c_unprepare_recovery(struct i2c_adapter *adap)
284{
285 uniphier_i2c_reset(i2c_get_adapdata(adap), false);
286}
287
288static struct i2c_bus_recovery_info uniphier_i2c_bus_recovery_info = {
289 .recover_bus = i2c_generic_scl_recovery,
290 .get_scl = uniphier_i2c_get_scl,
291 .set_scl = uniphier_i2c_set_scl,
292 .get_sda = uniphier_i2c_get_sda,
293 .unprepare_recovery = uniphier_i2c_unprepare_recovery,
294};
295
296static void uniphier_i2c_hw_init(struct uniphier_i2c_priv *priv)
297{
298 unsigned int cyc = priv->clk_cycle;
299
300 uniphier_i2c_reset(priv, true);
301
302
303
304
305
306
307
308 writel((cyc * 5 / 9 << 16) | cyc, priv->membase + UNIPHIER_I2C_CLK);
309
310 uniphier_i2c_reset(priv, false);
311}
312
313static int uniphier_i2c_probe(struct platform_device *pdev)
314{
315 struct device *dev = &pdev->dev;
316 struct uniphier_i2c_priv *priv;
317 u32 bus_speed;
318 unsigned long clk_rate;
319 int irq, ret;
320
321 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
322 if (!priv)
323 return -ENOMEM;
324
325 priv->membase = devm_platform_ioremap_resource(pdev, 0);
326 if (IS_ERR(priv->membase))
327 return PTR_ERR(priv->membase);
328
329 irq = platform_get_irq(pdev, 0);
330 if (irq < 0) {
331 dev_err(dev, "failed to get IRQ number\n");
332 return irq;
333 }
334
335 if (of_property_read_u32(dev->of_node, "clock-frequency", &bus_speed))
336 bus_speed = UNIPHIER_I2C_DEFAULT_SPEED;
337
338 if (!bus_speed || bus_speed > UNIPHIER_I2C_MAX_SPEED) {
339 dev_err(dev, "invalid clock-frequency %d\n", bus_speed);
340 return -EINVAL;
341 }
342
343 priv->clk = devm_clk_get(dev, NULL);
344 if (IS_ERR(priv->clk)) {
345 dev_err(dev, "failed to get clock\n");
346 return PTR_ERR(priv->clk);
347 }
348
349 ret = clk_prepare_enable(priv->clk);
350 if (ret)
351 return ret;
352
353 clk_rate = clk_get_rate(priv->clk);
354 if (!clk_rate) {
355 dev_err(dev, "input clock rate should not be zero\n");
356 ret = -EINVAL;
357 goto disable_clk;
358 }
359
360 priv->clk_cycle = clk_rate / bus_speed;
361 init_completion(&priv->comp);
362 priv->adap.owner = THIS_MODULE;
363 priv->adap.algo = &uniphier_i2c_algo;
364 priv->adap.dev.parent = dev;
365 priv->adap.dev.of_node = dev->of_node;
366 strlcpy(priv->adap.name, "UniPhier I2C", sizeof(priv->adap.name));
367 priv->adap.bus_recovery_info = &uniphier_i2c_bus_recovery_info;
368 i2c_set_adapdata(&priv->adap, priv);
369 platform_set_drvdata(pdev, priv);
370
371 uniphier_i2c_hw_init(priv);
372
373 ret = devm_request_irq(dev, irq, uniphier_i2c_interrupt, 0, pdev->name,
374 priv);
375 if (ret) {
376 dev_err(dev, "failed to request irq %d\n", irq);
377 goto disable_clk;
378 }
379
380 ret = i2c_add_adapter(&priv->adap);
381disable_clk:
382 if (ret)
383 clk_disable_unprepare(priv->clk);
384
385 return ret;
386}
387
388static int uniphier_i2c_remove(struct platform_device *pdev)
389{
390 struct uniphier_i2c_priv *priv = platform_get_drvdata(pdev);
391
392 i2c_del_adapter(&priv->adap);
393 clk_disable_unprepare(priv->clk);
394
395 return 0;
396}
397
398static int __maybe_unused uniphier_i2c_suspend(struct device *dev)
399{
400 struct uniphier_i2c_priv *priv = dev_get_drvdata(dev);
401
402 clk_disable_unprepare(priv->clk);
403
404 return 0;
405}
406
407static int __maybe_unused uniphier_i2c_resume(struct device *dev)
408{
409 struct uniphier_i2c_priv *priv = dev_get_drvdata(dev);
410 int ret;
411
412 ret = clk_prepare_enable(priv->clk);
413 if (ret)
414 return ret;
415
416 uniphier_i2c_hw_init(priv);
417
418 return 0;
419}
420
421static const struct dev_pm_ops uniphier_i2c_pm_ops = {
422 SET_SYSTEM_SLEEP_PM_OPS(uniphier_i2c_suspend, uniphier_i2c_resume)
423};
424
425static const struct of_device_id uniphier_i2c_match[] = {
426 { .compatible = "socionext,uniphier-i2c" },
427 { }
428};
429MODULE_DEVICE_TABLE(of, uniphier_i2c_match);
430
431static struct platform_driver uniphier_i2c_drv = {
432 .probe = uniphier_i2c_probe,
433 .remove = uniphier_i2c_remove,
434 .driver = {
435 .name = "uniphier-i2c",
436 .of_match_table = uniphier_i2c_match,
437 .pm = &uniphier_i2c_pm_ops,
438 },
439};
440module_platform_driver(uniphier_i2c_drv);
441
442MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
443MODULE_DESCRIPTION("UniPhier I2C bus driver");
444MODULE_LICENSE("GPL");
445
