1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Loongson-2K/Loongson LS7A I2C controller mode driver
4 *
5 * Copyright (C) 2013 Loongson Technology Corporation Limited.
6 * Copyright (C) 2014-2017 Lemote, Inc.
7 * Copyright (C) 2018-2022 Loongson Technology Corporation Limited.
8 *
9 * Originally written by liushaozong
10 * Rewritten for mainline by Binbin Zhou <zhoubinbin@loongson.cn>
11 */
12
13 #include <linux/bits.h>
14 #include <linux/completion.h>
15 #include <linux/device.h>
16 #include <linux/iopoll.h>
17 #include <linux/i2c.h>
18 #include <linux/init.h>
19 #include <linux/interrupt.h>
20 #include <linux/io.h>
21 #include <linux/kernel.h>
22 #include <linux/module.h>
23 #include <linux/pm_runtime.h>
24 #include <linux/platform_device.h>
25 #include <linux/property.h>
26 #include <linux/units.h>
27
28 /* I2C Registers */
29 #define I2C_LS2X_PRER 0x0 /* Freq Division Register(16 bits) */
30 #define I2C_LS2X_CTR 0x2 /* Control Register */
31 #define I2C_LS2X_TXR 0x3 /* Transport Data Register */
32 #define I2C_LS2X_RXR 0x3 /* Receive Data Register */
33 #define I2C_LS2X_CR 0x4 /* Command Control Register */
34 #define I2C_LS2X_SR 0x4 /* State Register */
35
36 /* Command Control Register Bit */
37 #define LS2X_CR_START BIT(7) /* Start signal */
38 #define LS2X_CR_STOP BIT(6) /* Stop signal */
39 #define LS2X_CR_READ BIT(5) /* Read signal */
40 #define LS2X_CR_WRITE BIT(4) /* Write signal */
41 #define LS2X_CR_ACK BIT(3) /* Response signal */
42 #define LS2X_CR_IACK BIT(0) /* Interrupt response signal */
43
44 /* State Register Bit */
45 #define LS2X_SR_NOACK BIT(7) /* Receive NACK */
46 #define LS2X_SR_BUSY BIT(6) /* Bus busy state */
47 #define LS2X_SR_AL BIT(5) /* Arbitration lost */
48 #define LS2X_SR_TIP BIT(1) /* Transmission state */
49 #define LS2X_SR_IF BIT(0) /* Interrupt flag */
50
51 /* Control Register Bit */
52 #define LS2X_CTR_EN BIT(7) /* 0: I2c frequency setting 1: Normal */
53 #define LS2X_CTR_IEN BIT(6) /* Enable i2c interrupt */
54 #define LS2X_CTR_MST BIT(5) /* 0: Target mode 1: Controller mode */
55 #define CTR_FREQ_MASK GENMASK(7, 6)
56 #define CTR_READY_MASK GENMASK(7, 5)
57
58 /* The PCLK frequency from LPB */
59 #define LS2X_I2C_PCLK_FREQ (50 * HZ_PER_MHZ)
60
61 /* The default bus frequency, which is an empirical value */
62 #define LS2X_I2C_FREQ_STD (33 * HZ_PER_KHZ)
63
64 struct ls2x_i2c_priv {
65 struct i2c_adapter adapter;
66 void __iomem *base;
67 struct i2c_timings i2c_t;
68 struct completion cmd_complete;
69 };
70
71 /*
72 * Interrupt service routine.
73 * This gets called whenever an I2C interrupt occurs.
74 */
ls2x_i2c_isr(int this_irq,void * dev_id)75 static irqreturn_t ls2x_i2c_isr(int this_irq, void *dev_id)
76 {
77 struct ls2x_i2c_priv *priv = dev_id;
78
79 if (!(readb(priv->base + I2C_LS2X_SR) & LS2X_SR_IF))
80 return IRQ_NONE;
81
82 writeb(LS2X_CR_IACK, priv->base + I2C_LS2X_CR);
83 complete(&priv->cmd_complete);
84 return IRQ_HANDLED;
85 }
86
87 /*
88 * The ls2x i2c controller supports standard mode and fast mode, so the
89 * maximum bus frequency is '400kHz'.
90 * The bus frequency is set to the empirical value of '33KHz' by default,
91 * but it can also be taken from ACPI or FDT for compatibility with more
92 * devices.
93 */
ls2x_i2c_adjust_bus_speed(struct ls2x_i2c_priv * priv)94 static void ls2x_i2c_adjust_bus_speed(struct ls2x_i2c_priv *priv)
95 {
96 struct i2c_timings *t = &priv->i2c_t;
97 struct device *dev = priv->adapter.dev.parent;
98 u32 acpi_speed = i2c_acpi_find_bus_speed(dev);
99
100 i2c_parse_fw_timings(dev, t, false);
101
102 if (acpi_speed || t->bus_freq_hz)
103 t->bus_freq_hz = max(t->bus_freq_hz, acpi_speed);
104 else
105 t->bus_freq_hz = LS2X_I2C_FREQ_STD;
106
107 /* Calculate and set i2c frequency. */
108 writew(LS2X_I2C_PCLK_FREQ / (5 * t->bus_freq_hz) - 1,
109 priv->base + I2C_LS2X_PRER);
110 }
111
ls2x_i2c_init(struct ls2x_i2c_priv * priv)112 static void ls2x_i2c_init(struct ls2x_i2c_priv *priv)
113 {
114 /* Set i2c frequency setting mode and disable interrupts. */
115 writeb(readb(priv->base + I2C_LS2X_CTR) & ~CTR_FREQ_MASK,
116 priv->base + I2C_LS2X_CTR);
117
118 ls2x_i2c_adjust_bus_speed(priv);
119
120 /* Set i2c normal operating mode and enable interrupts. */
121 writeb(readb(priv->base + I2C_LS2X_CTR) | CTR_READY_MASK,
122 priv->base + I2C_LS2X_CTR);
123 }
124
ls2x_i2c_xfer_byte(struct ls2x_i2c_priv * priv,u8 txdata,u8 * rxdatap)125 static int ls2x_i2c_xfer_byte(struct ls2x_i2c_priv *priv, u8 txdata, u8 *rxdatap)
126 {
127 u8 rxdata;
128 unsigned long time_left;
129
130 writeb(txdata, priv->base + I2C_LS2X_CR);
131
132 time_left = wait_for_completion_timeout(&priv->cmd_complete,
133 priv->adapter.timeout);
134 if (!time_left)
135 return -ETIMEDOUT;
136
137 rxdata = readb(priv->base + I2C_LS2X_SR);
138 if (rxdatap)
139 *rxdatap = rxdata;
140
141 return 0;
142 }
143
ls2x_i2c_send_byte(struct ls2x_i2c_priv * priv,u8 txdata)144 static int ls2x_i2c_send_byte(struct ls2x_i2c_priv *priv, u8 txdata)
145 {
146 int ret;
147 u8 rxdata;
148
149 ret = ls2x_i2c_xfer_byte(priv, txdata, &rxdata);
150 if (ret)
151 return ret;
152
153 if (rxdata & LS2X_SR_AL)
154 return -EAGAIN;
155
156 if (rxdata & LS2X_SR_NOACK)
157 return -ENXIO;
158
159 return 0;
160 }
161
ls2x_i2c_stop(struct ls2x_i2c_priv * priv)162 static int ls2x_i2c_stop(struct ls2x_i2c_priv *priv)
163 {
164 u8 value;
165
166 writeb(LS2X_CR_STOP, priv->base + I2C_LS2X_CR);
167 return readb_poll_timeout(priv->base + I2C_LS2X_SR, value,
168 !(value & LS2X_SR_BUSY), 100,
169 jiffies_to_usecs(priv->adapter.timeout));
170 }
171
ls2x_i2c_start(struct ls2x_i2c_priv * priv,struct i2c_msg * msgs)172 static int ls2x_i2c_start(struct ls2x_i2c_priv *priv, struct i2c_msg *msgs)
173 {
174 reinit_completion(&priv->cmd_complete);
175
176 writeb(i2c_8bit_addr_from_msg(msgs), priv->base + I2C_LS2X_TXR);
177 return ls2x_i2c_send_byte(priv, LS2X_CR_START | LS2X_CR_WRITE);
178 }
179
ls2x_i2c_rx(struct ls2x_i2c_priv * priv,struct i2c_msg * msg)180 static int ls2x_i2c_rx(struct ls2x_i2c_priv *priv, struct i2c_msg *msg)
181 {
182 int ret;
183 u8 rxdata, *buf = msg->buf;
184 u16 len = msg->len;
185
186 /* Contains steps to send start condition and address. */
187 ret = ls2x_i2c_start(priv, msg);
188 if (ret)
189 return ret;
190
191 while (len--) {
192 ret = ls2x_i2c_xfer_byte(priv,
193 LS2X_CR_READ | (len ? 0 : LS2X_CR_ACK),
194 &rxdata);
195 if (ret)
196 return ret;
197
198 *buf++ = readb(priv->base + I2C_LS2X_RXR);
199 }
200
201 return 0;
202 }
203
ls2x_i2c_tx(struct ls2x_i2c_priv * priv,struct i2c_msg * msg)204 static int ls2x_i2c_tx(struct ls2x_i2c_priv *priv, struct i2c_msg *msg)
205 {
206 int ret;
207 u8 *buf = msg->buf;
208 u16 len = msg->len;
209
210 /* Contains steps to send start condition and address. */
211 ret = ls2x_i2c_start(priv, msg);
212 if (ret)
213 return ret;
214
215 while (len--) {
216 writeb(*buf++, priv->base + I2C_LS2X_TXR);
217
218 ret = ls2x_i2c_send_byte(priv, LS2X_CR_WRITE);
219 if (ret)
220 return ret;
221 }
222
223 return 0;
224 }
225
ls2x_i2c_xfer_one(struct ls2x_i2c_priv * priv,struct i2c_msg * msg,bool stop)226 static int ls2x_i2c_xfer_one(struct ls2x_i2c_priv *priv,
227 struct i2c_msg *msg, bool stop)
228 {
229 int ret;
230
231 if (msg->flags & I2C_M_RD)
232 ret = ls2x_i2c_rx(priv, msg);
233 else
234 ret = ls2x_i2c_tx(priv, msg);
235
236 if (ret < 0) {
237 /* Fatel error. Needs reinit. */
238 if (ret == -ETIMEDOUT)
239 ls2x_i2c_init(priv);
240
241 return ret;
242 }
243
244 if (stop) {
245 /* Failed to issue STOP. Needs reinit. */
246 ret = ls2x_i2c_stop(priv);
247 if (ret)
248 ls2x_i2c_init(priv);
249 }
250
251 return ret;
252 }
253
ls2x_i2c_xfer(struct i2c_adapter * adap,struct i2c_msg * msgs,int num)254 static int ls2x_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
255 {
256 int ret;
257 struct i2c_msg *msg, *emsg = msgs + num;
258 struct ls2x_i2c_priv *priv = i2c_get_adapdata(adap);
259
260 for (msg = msgs; msg < emsg; msg++) {
261 ret = ls2x_i2c_xfer_one(priv, msg, msg == emsg - 1);
262 if (ret)
263 return ret;
264 }
265
266 return num;
267 }
268
ls2x_i2c_func(struct i2c_adapter * adap)269 static unsigned int ls2x_i2c_func(struct i2c_adapter *adap)
270 {
271 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
272 }
273
274 static const struct i2c_algorithm ls2x_i2c_algo = {
275 .xfer = ls2x_i2c_xfer,
276 .functionality = ls2x_i2c_func,
277 };
278
ls2x_i2c_probe(struct platform_device * pdev)279 static int ls2x_i2c_probe(struct platform_device *pdev)
280 {
281 int ret, irq;
282 struct i2c_adapter *adap;
283 struct ls2x_i2c_priv *priv;
284 struct device *dev = &pdev->dev;
285
286 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
287 if (!priv)
288 return -ENOMEM;
289
290 /* Map hardware registers */
291 priv->base = devm_platform_ioremap_resource(pdev, 0);
292 if (IS_ERR(priv->base))
293 return PTR_ERR(priv->base);
294
295 irq = platform_get_irq(pdev, 0);
296 if (irq < 0)
297 return irq;
298
299 /* Add the i2c adapter */
300 adap = &priv->adapter;
301 adap->retries = 5;
302 adap->nr = pdev->id;
303 adap->dev.parent = dev;
304 adap->owner = THIS_MODULE;
305 adap->algo = &ls2x_i2c_algo;
306 adap->timeout = msecs_to_jiffies(100);
307 device_set_node(&adap->dev, dev_fwnode(dev));
308 i2c_set_adapdata(adap, priv);
309 strscpy(adap->name, pdev->name, sizeof(adap->name));
310 init_completion(&priv->cmd_complete);
311 platform_set_drvdata(pdev, priv);
312
313 ls2x_i2c_init(priv);
314
315 ret = devm_request_irq(dev, irq, ls2x_i2c_isr, IRQF_SHARED, "ls2x-i2c",
316 priv);
317 if (ret < 0)
318 return dev_err_probe(dev, ret, "Unable to request irq %d\n", irq);
319
320 return devm_i2c_add_adapter(dev, adap);
321 }
322
ls2x_i2c_suspend(struct device * dev)323 static int ls2x_i2c_suspend(struct device *dev)
324 {
325 struct ls2x_i2c_priv *priv = dev_get_drvdata(dev);
326
327 /* Disable interrupts */
328 writeb(readb(priv->base + I2C_LS2X_CTR) & ~LS2X_CTR_IEN,
329 priv->base + I2C_LS2X_CTR);
330
331 return 0;
332 }
333
ls2x_i2c_resume(struct device * dev)334 static int ls2x_i2c_resume(struct device *dev)
335 {
336 ls2x_i2c_init(dev_get_drvdata(dev));
337 return 0;
338 }
339
340 static DEFINE_RUNTIME_DEV_PM_OPS(ls2x_i2c_pm_ops,
341 ls2x_i2c_suspend, ls2x_i2c_resume, NULL);
342
343 static const struct of_device_id ls2x_i2c_id_table[] = {
344 { .compatible = "loongson,ls2k-i2c" },
345 { .compatible = "loongson,ls7a-i2c" },
346 { /* sentinel */ }
347 };
348 MODULE_DEVICE_TABLE(of, ls2x_i2c_id_table);
349
350 static const struct acpi_device_id ls2x_i2c_acpi_match[] = {
351 { "LOON0004" }, /* Loongson LS7A */
352 { }
353 };
354 MODULE_DEVICE_TABLE(acpi, ls2x_i2c_acpi_match);
355
356 static struct platform_driver ls2x_i2c_driver = {
357 .probe = ls2x_i2c_probe,
358 .driver = {
359 .name = "ls2x-i2c",
360 .pm = pm_sleep_ptr(&ls2x_i2c_pm_ops),
361 .of_match_table = ls2x_i2c_id_table,
362 .acpi_match_table = ls2x_i2c_acpi_match,
363 },
364 };
365 module_platform_driver(ls2x_i2c_driver);
366
367 MODULE_DESCRIPTION("Loongson LS2X I2C Bus driver");
368 MODULE_AUTHOR("Loongson Technology Corporation Limited");
369 MODULE_LICENSE("GPL");
370