1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Microchip CoreI2C I2C controller driver
4  *
5  * Copyright (c) 2018-2022 Microchip Corporation. All rights reserved.
6  *
7  * Author: Daire McNamara <daire.mcnamara@microchip.com>
8  * Author: Conor Dooley <conor.dooley@microchip.com>
9  */
10 #include <linux/clk.h>
11 #include <linux/clkdev.h>
12 #include <linux/err.h>
13 #include <linux/i2c.h>
14 #include <linux/interrupt.h>
15 #include <linux/io.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/platform_device.h>
19 
20 #define CORE_I2C_CTRL	(0x00)
21 #define  CTRL_CR0	BIT(0)
22 #define  CTRL_CR1	BIT(1)
23 #define  CTRL_AA	BIT(2)
24 #define  CTRL_SI	BIT(3)
25 #define  CTRL_STO	BIT(4)
26 #define  CTRL_STA	BIT(5)
27 #define  CTRL_ENS1	BIT(6)
28 #define  CTRL_CR2	BIT(7)
29 
30 #define STATUS_BUS_ERROR			(0x00)
31 #define STATUS_M_START_SENT			(0x08)
32 #define STATUS_M_REPEATED_START_SENT		(0x10)
33 #define STATUS_M_SLAW_ACK			(0x18)
34 #define STATUS_M_SLAW_NACK			(0x20)
35 #define STATUS_M_TX_DATA_ACK			(0x28)
36 #define STATUS_M_TX_DATA_NACK			(0x30)
37 #define STATUS_M_ARB_LOST			(0x38)
38 #define STATUS_M_SLAR_ACK			(0x40)
39 #define STATUS_M_SLAR_NACK			(0x48)
40 #define STATUS_M_RX_DATA_ACKED			(0x50)
41 #define STATUS_M_RX_DATA_NACKED			(0x58)
42 #define STATUS_S_SLAW_ACKED			(0x60)
43 #define STATUS_S_ARB_LOST_SLAW_ACKED		(0x68)
44 #define STATUS_S_GENERAL_CALL_ACKED		(0x70)
45 #define STATUS_S_ARB_LOST_GENERAL_CALL_ACKED	(0x78)
46 #define STATUS_S_RX_DATA_ACKED			(0x80)
47 #define STATUS_S_RX_DATA_NACKED			(0x88)
48 #define STATUS_S_GENERAL_CALL_RX_DATA_ACKED	(0x90)
49 #define STATUS_S_GENERAL_CALL_RX_DATA_NACKED	(0x98)
50 #define STATUS_S_RX_STOP			(0xA0)
51 #define STATUS_S_SLAR_ACKED			(0xA8)
52 #define STATUS_S_ARB_LOST_SLAR_ACKED		(0xB0)
53 #define STATUS_S_TX_DATA_ACK			(0xB8)
54 #define STATUS_S_TX_DATA_NACK			(0xC0)
55 #define STATUS_LAST_DATA_ACK			(0xC8)
56 #define STATUS_M_SMB_MASTER_RESET		(0xD0)
57 #define STATUS_S_SCL_LOW_TIMEOUT		(0xD8) /* 25 ms */
58 #define STATUS_NO_STATE_INFO			(0xF8)
59 
60 #define CORE_I2C_STATUS		(0x04)
61 #define CORE_I2C_DATA		(0x08)
62 #define WRITE_BIT		(0x0)
63 #define READ_BIT		(0x1)
64 #define SLAVE_ADDR_SHIFT	(1)
65 #define CORE_I2C_SLAVE0_ADDR	(0x0c)
66 #define GENERAL_CALL_BIT	(0x0)
67 #define CORE_I2C_SMBUS		(0x10)
68 #define SMBALERT_INT_ENB	(0x0)
69 #define SMBSUS_INT_ENB		(0x1)
70 #define SMBUS_ENB		(0x2)
71 #define SMBALERT_NI_STATUS	(0x3)
72 #define SMBALERT_NO_CTRL	(0x4)
73 #define SMBSUS_NI_STATUS	(0x5)
74 #define SMBSUS_NO_CTRL		(0x6)
75 #define SMBUS_RESET		(0x7)
76 #define CORE_I2C_FREQ		(0x14)
77 #define CORE_I2C_GLITCHREG	(0x18)
78 #define CORE_I2C_SLAVE1_ADDR	(0x1c)
79 
80 #define PCLK_DIV_960	(CTRL_CR2)
81 #define PCLK_DIV_256	(0)
82 #define PCLK_DIV_224	(CTRL_CR0)
83 #define PCLK_DIV_192	(CTRL_CR1)
84 #define PCLK_DIV_160	(CTRL_CR0 | CTRL_CR1)
85 #define PCLK_DIV_120	(CTRL_CR0 | CTRL_CR2)
86 #define PCLK_DIV_60	(CTRL_CR1 | CTRL_CR2)
87 #define BCLK_DIV_8	(CTRL_CR0 | CTRL_CR1 | CTRL_CR2)
88 #define CLK_MASK	(CTRL_CR0 | CTRL_CR1 | CTRL_CR2)
89 
90 /**
91  * struct mchp_corei2c_dev - Microchip CoreI2C device private data
92  *
93  * @base:		pointer to register struct
94  * @dev:		device reference
95  * @i2c_clk:		clock reference for i2c input clock
96  * @buf:		pointer to msg buffer for easier use
97  * @msg_complete:	xfer completion object
98  * @adapter:		core i2c abstraction
99  * @msg_err:		error code for completed message
100  * @bus_clk_rate:	current i2c bus clock rate
101  * @isr_status:		cached copy of local ISR status
102  * @msg_len:		number of bytes transferred in msg
103  * @addr:		address of the current slave
104  */
105 struct mchp_corei2c_dev {
106 	void __iomem *base;
107 	struct device *dev;
108 	struct clk *i2c_clk;
109 	u8 *buf;
110 	struct completion msg_complete;
111 	struct i2c_adapter adapter;
112 	int msg_err;
113 	u32 bus_clk_rate;
114 	u32 isr_status;
115 	u16 msg_len;
116 	u8 addr;
117 };
118 
119 static void mchp_corei2c_core_disable(struct mchp_corei2c_dev *idev)
120 {
121 	u8 ctrl = readb(idev->base + CORE_I2C_CTRL);
122 
123 	ctrl &= ~CTRL_ENS1;
124 	writeb(ctrl, idev->base + CORE_I2C_CTRL);
125 }
126 
127 static void mchp_corei2c_core_enable(struct mchp_corei2c_dev *idev)
128 {
129 	u8 ctrl = readb(idev->base + CORE_I2C_CTRL);
130 
131 	ctrl |= CTRL_ENS1;
132 	writeb(ctrl, idev->base + CORE_I2C_CTRL);
133 }
134 
135 static void mchp_corei2c_reset(struct mchp_corei2c_dev *idev)
136 {
137 	mchp_corei2c_core_disable(idev);
138 	mchp_corei2c_core_enable(idev);
139 }
140 
141 static inline void mchp_corei2c_stop(struct mchp_corei2c_dev *idev)
142 {
143 	u8 ctrl = readb(idev->base + CORE_I2C_CTRL);
144 
145 	ctrl |= CTRL_STO;
146 	writeb(ctrl, idev->base + CORE_I2C_CTRL);
147 }
148 
149 static inline int mchp_corei2c_set_divisor(u32 rate,
150 					   struct mchp_corei2c_dev *idev)
151 {
152 	u8 clkval, ctrl;
153 
154 	if (rate >= 960)
155 		clkval = PCLK_DIV_960;
156 	else if (rate >= 256)
157 		clkval = PCLK_DIV_256;
158 	else if (rate >= 224)
159 		clkval = PCLK_DIV_224;
160 	else if (rate >= 192)
161 		clkval = PCLK_DIV_192;
162 	else if (rate >= 160)
163 		clkval = PCLK_DIV_160;
164 	else if (rate >= 120)
165 		clkval = PCLK_DIV_120;
166 	else if (rate >= 60)
167 		clkval = PCLK_DIV_60;
168 	else if (rate >= 8)
169 		clkval = BCLK_DIV_8;
170 	else
171 		return -EINVAL;
172 
173 	ctrl = readb(idev->base + CORE_I2C_CTRL);
174 	ctrl &= ~CLK_MASK;
175 	ctrl |= clkval;
176 	writeb(ctrl, idev->base + CORE_I2C_CTRL);
177 
178 	ctrl = readb(idev->base + CORE_I2C_CTRL);
179 	if ((ctrl & CLK_MASK) != clkval)
180 		return -EIO;
181 
182 	return 0;
183 }
184 
185 static int mchp_corei2c_init(struct mchp_corei2c_dev *idev)
186 {
187 	u32 clk_rate = clk_get_rate(idev->i2c_clk);
188 	u32 divisor = clk_rate / idev->bus_clk_rate;
189 	int ret;
190 
191 	ret = mchp_corei2c_set_divisor(divisor, idev);
192 	if (ret)
193 		return ret;
194 
195 	mchp_corei2c_reset(idev);
196 
197 	return 0;
198 }
199 
200 static void mchp_corei2c_empty_rx(struct mchp_corei2c_dev *idev)
201 {
202 	u8 ctrl;
203 
204 	if (idev->msg_len > 0) {
205 		*idev->buf++ = readb(idev->base + CORE_I2C_DATA);
206 		idev->msg_len--;
207 	}
208 
209 	if (idev->msg_len <= 1) {
210 		ctrl = readb(idev->base + CORE_I2C_CTRL);
211 		ctrl &= ~CTRL_AA;
212 		writeb(ctrl, idev->base + CORE_I2C_CTRL);
213 	}
214 }
215 
216 static int mchp_corei2c_fill_tx(struct mchp_corei2c_dev *idev)
217 {
218 	if (idev->msg_len > 0)
219 		writeb(*idev->buf++, idev->base + CORE_I2C_DATA);
220 	idev->msg_len--;
221 
222 	return 0;
223 }
224 
225 static irqreturn_t mchp_corei2c_handle_isr(struct mchp_corei2c_dev *idev)
226 {
227 	u32 status = idev->isr_status;
228 	u8 ctrl;
229 	bool last_byte = false, finished = false;
230 
231 	if (!idev->buf)
232 		return IRQ_NONE;
233 
234 	switch (status) {
235 	case STATUS_M_START_SENT:
236 	case STATUS_M_REPEATED_START_SENT:
237 		ctrl = readb(idev->base + CORE_I2C_CTRL);
238 		ctrl &= ~CTRL_STA;
239 		writeb(idev->addr, idev->base + CORE_I2C_DATA);
240 		writeb(ctrl, idev->base + CORE_I2C_CTRL);
241 		if (idev->msg_len == 0)
242 			finished = true;
243 		break;
244 	case STATUS_M_ARB_LOST:
245 		idev->msg_err = -EAGAIN;
246 		finished = true;
247 		break;
248 	case STATUS_M_SLAW_ACK:
249 	case STATUS_M_TX_DATA_ACK:
250 		if (idev->msg_len > 0)
251 			mchp_corei2c_fill_tx(idev);
252 		else
253 			last_byte = true;
254 		break;
255 	case STATUS_M_TX_DATA_NACK:
256 	case STATUS_M_SLAR_NACK:
257 	case STATUS_M_SLAW_NACK:
258 		idev->msg_err = -ENXIO;
259 		last_byte = true;
260 		break;
261 	case STATUS_M_SLAR_ACK:
262 		ctrl = readb(idev->base + CORE_I2C_CTRL);
263 		if (idev->msg_len == 1u) {
264 			ctrl &= ~CTRL_AA;
265 			writeb(ctrl, idev->base + CORE_I2C_CTRL);
266 		} else {
267 			ctrl |= CTRL_AA;
268 			writeb(ctrl, idev->base + CORE_I2C_CTRL);
269 		}
270 		if (idev->msg_len < 1u)
271 			last_byte = true;
272 		break;
273 	case STATUS_M_RX_DATA_ACKED:
274 		mchp_corei2c_empty_rx(idev);
275 		break;
276 	case STATUS_M_RX_DATA_NACKED:
277 		mchp_corei2c_empty_rx(idev);
278 		if (idev->msg_len == 0)
279 			last_byte = true;
280 		break;
281 	default:
282 		break;
283 	}
284 
285 	/* On the last byte to be transmitted, send STOP */
286 	if (last_byte)
287 		mchp_corei2c_stop(idev);
288 
289 	if (last_byte || finished)
290 		complete(&idev->msg_complete);
291 
292 	return IRQ_HANDLED;
293 }
294 
295 static irqreturn_t mchp_corei2c_isr(int irq, void *_dev)
296 {
297 	struct mchp_corei2c_dev *idev = _dev;
298 	irqreturn_t ret = IRQ_NONE;
299 	u8 ctrl;
300 
301 	ctrl = readb(idev->base + CORE_I2C_CTRL);
302 	if (ctrl & CTRL_SI) {
303 		idev->isr_status = readb(idev->base + CORE_I2C_STATUS);
304 		ret = mchp_corei2c_handle_isr(idev);
305 	}
306 
307 	ctrl = readb(idev->base + CORE_I2C_CTRL);
308 	ctrl &= ~CTRL_SI;
309 	writeb(ctrl, idev->base + CORE_I2C_CTRL);
310 
311 	return ret;
312 }
313 
314 static int mchp_corei2c_xfer_msg(struct mchp_corei2c_dev *idev,
315 				 struct i2c_msg *msg)
316 {
317 	u8 ctrl;
318 	unsigned long time_left;
319 
320 	idev->addr = i2c_8bit_addr_from_msg(msg);
321 	idev->msg_len = msg->len;
322 	idev->buf = msg->buf;
323 	idev->msg_err = 0;
324 
325 	reinit_completion(&idev->msg_complete);
326 
327 	mchp_corei2c_core_enable(idev);
328 
329 	ctrl = readb(idev->base + CORE_I2C_CTRL);
330 	ctrl |= CTRL_STA;
331 	writeb(ctrl, idev->base + CORE_I2C_CTRL);
332 
333 	time_left = wait_for_completion_timeout(&idev->msg_complete,
334 						idev->adapter.timeout);
335 	if (!time_left)
336 		return -ETIMEDOUT;
337 
338 	return idev->msg_err;
339 }
340 
341 static int mchp_corei2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
342 			     int num)
343 {
344 	struct mchp_corei2c_dev *idev = i2c_get_adapdata(adap);
345 	int i, ret;
346 
347 	for (i = 0; i < num; i++) {
348 		ret = mchp_corei2c_xfer_msg(idev, msgs++);
349 		if (ret)
350 			return ret;
351 	}
352 
353 	return num;
354 }
355 
356 static u32 mchp_corei2c_func(struct i2c_adapter *adap)
357 {
358 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
359 }
360 
361 static const struct i2c_algorithm mchp_corei2c_algo = {
362 	.master_xfer = mchp_corei2c_xfer,
363 	.functionality = mchp_corei2c_func,
364 };
365 
366 static int mchp_corei2c_probe(struct platform_device *pdev)
367 {
368 	struct mchp_corei2c_dev *idev;
369 	struct resource *res;
370 	int irq, ret;
371 
372 	idev = devm_kzalloc(&pdev->dev, sizeof(*idev), GFP_KERNEL);
373 	if (!idev)
374 		return -ENOMEM;
375 
376 	idev->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
377 	if (IS_ERR(idev->base))
378 		return PTR_ERR(idev->base);
379 
380 	irq = platform_get_irq(pdev, 0);
381 	if (irq <= 0)
382 		return dev_err_probe(&pdev->dev, -ENXIO,
383 				     "invalid IRQ %d for I2C controller\n", irq);
384 
385 	idev->i2c_clk = devm_clk_get(&pdev->dev, NULL);
386 	if (IS_ERR(idev->i2c_clk))
387 		return dev_err_probe(&pdev->dev, PTR_ERR(idev->i2c_clk),
388 				     "missing clock\n");
389 
390 	idev->dev = &pdev->dev;
391 	init_completion(&idev->msg_complete);
392 
393 	ret = device_property_read_u32(idev->dev, "clock-frequency",
394 				       &idev->bus_clk_rate);
395 	if (ret || !idev->bus_clk_rate) {
396 		dev_info(&pdev->dev, "default to 100kHz\n");
397 		idev->bus_clk_rate = 100000;
398 	}
399 
400 	if (idev->bus_clk_rate > 400000)
401 		return dev_err_probe(&pdev->dev, -EINVAL,
402 				     "clock-frequency too high: %d\n",
403 				     idev->bus_clk_rate);
404 
405 	/*
406 	 * This driver supports both the hard peripherals & soft FPGA cores.
407 	 * The hard peripherals do not have shared IRQs, but we don't have
408 	 * control over what way the interrupts are wired for the soft cores.
409 	 */
410 	ret = devm_request_irq(&pdev->dev, irq, mchp_corei2c_isr, IRQF_SHARED,
411 			       pdev->name, idev);
412 	if (ret)
413 		return dev_err_probe(&pdev->dev, ret,
414 				     "failed to claim irq %d\n", irq);
415 
416 	ret = clk_prepare_enable(idev->i2c_clk);
417 	if (ret)
418 		return dev_err_probe(&pdev->dev, ret,
419 				     "failed to enable clock\n");
420 
421 	ret = mchp_corei2c_init(idev);
422 	if (ret) {
423 		clk_disable_unprepare(idev->i2c_clk);
424 		return dev_err_probe(&pdev->dev, ret, "failed to program clock divider\n");
425 	}
426 
427 	i2c_set_adapdata(&idev->adapter, idev);
428 	snprintf(idev->adapter.name, sizeof(idev->adapter.name),
429 		 "Microchip I2C hw bus at %08lx", (unsigned long)res->start);
430 	idev->adapter.owner = THIS_MODULE;
431 	idev->adapter.algo = &mchp_corei2c_algo;
432 	idev->adapter.dev.parent = &pdev->dev;
433 	idev->adapter.dev.of_node = pdev->dev.of_node;
434 	idev->adapter.timeout = HZ;
435 
436 	platform_set_drvdata(pdev, idev);
437 
438 	ret = i2c_add_adapter(&idev->adapter);
439 	if (ret) {
440 		clk_disable_unprepare(idev->i2c_clk);
441 		return ret;
442 	}
443 
444 	dev_info(&pdev->dev, "registered CoreI2C bus driver\n");
445 
446 	return 0;
447 }
448 
449 static void mchp_corei2c_remove(struct platform_device *pdev)
450 {
451 	struct mchp_corei2c_dev *idev = platform_get_drvdata(pdev);
452 
453 	clk_disable_unprepare(idev->i2c_clk);
454 	i2c_del_adapter(&idev->adapter);
455 }
456 
457 static const struct of_device_id mchp_corei2c_of_match[] = {
458 	{ .compatible = "microchip,mpfs-i2c" },
459 	{ .compatible = "microchip,corei2c-rtl-v7" },
460 	{},
461 };
462 MODULE_DEVICE_TABLE(of, mchp_corei2c_of_match);
463 
464 static struct platform_driver mchp_corei2c_driver = {
465 	.probe = mchp_corei2c_probe,
466 	.remove_new = mchp_corei2c_remove,
467 	.driver = {
468 		.name = "microchip-corei2c",
469 		.of_match_table = mchp_corei2c_of_match,
470 	},
471 };
472 
473 module_platform_driver(mchp_corei2c_driver);
474 
475 MODULE_DESCRIPTION("Microchip CoreI2C bus driver");
476 MODULE_AUTHOR("Daire McNamara <daire.mcnamara@microchip.com>");
477 MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>");
478 MODULE_LICENSE("GPL");
479