1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2006-2007 PA Semi, Inc
4  *
5  * SMBus host driver for PA Semi PWRficient
6  */
7 
8 #include <linux/module.h>
9 #include <linux/pci.h>
10 #include <linux/kernel.h>
11 #include <linux/stddef.h>
12 #include <linux/sched.h>
13 #include <linux/i2c.h>
14 #include <linux/delay.h>
15 #include <linux/slab.h>
16 #include <linux/io.h>
17 
18 #include "i2c-pasemi-core.h"
19 
20 /* Register offsets */
21 #define REG_MTXFIFO	0x00
22 #define REG_MRXFIFO	0x04
23 #define REG_SMSTA	0x14
24 #define REG_IMASK	0x18
25 #define REG_CTL		0x1c
26 #define REG_REV		0x28
27 
28 /* Register defs */
29 #define MTXFIFO_READ	0x00000400
30 #define MTXFIFO_STOP	0x00000200
31 #define MTXFIFO_START	0x00000100
32 #define MTXFIFO_DATA_M	0x000000ff
33 
34 #define MRXFIFO_EMPTY	0x00000100
35 #define MRXFIFO_DATA_M	0x000000ff
36 
37 #define SMSTA_XEN	0x08000000
38 #define SMSTA_MTN	0x00200000
39 
40 #define CTL_MRR		0x00000400
41 #define CTL_MTR		0x00000200
42 #define CTL_EN		0x00000800
43 #define CTL_CLK_M	0x000000ff
44 
45 static inline void reg_write(struct pasemi_smbus *smbus, int reg, int val)
46 {
47 	dev_dbg(smbus->dev, "smbus write reg %x val %08x\n", reg, val);
48 	iowrite32(val, smbus->ioaddr + reg);
49 }
50 
51 static inline int reg_read(struct pasemi_smbus *smbus, int reg)
52 {
53 	int ret;
54 	ret = ioread32(smbus->ioaddr + reg);
55 	dev_dbg(smbus->dev, "smbus read reg %x val %08x\n", reg, ret);
56 	return ret;
57 }
58 
59 #define TXFIFO_WR(smbus, reg)	reg_write((smbus), REG_MTXFIFO, (reg))
60 #define RXFIFO_RD(smbus)	reg_read((smbus), REG_MRXFIFO)
61 
62 static void pasemi_reset(struct pasemi_smbus *smbus)
63 {
64 	u32 val = (CTL_MTR | CTL_MRR | (smbus->clk_div & CTL_CLK_M));
65 
66 	if (smbus->hw_rev >= 6)
67 		val |= CTL_EN;
68 
69 	reg_write(smbus, REG_CTL, val);
70 	reinit_completion(&smbus->irq_completion);
71 }
72 
73 static void pasemi_smb_clear(struct pasemi_smbus *smbus)
74 {
75 	unsigned int status;
76 
77 	status = reg_read(smbus, REG_SMSTA);
78 	reg_write(smbus, REG_SMSTA, status);
79 }
80 
81 static int pasemi_smb_waitready(struct pasemi_smbus *smbus)
82 {
83 	int timeout = 100;
84 	unsigned int status;
85 
86 	if (smbus->use_irq) {
87 		reinit_completion(&smbus->irq_completion);
88 		reg_write(smbus, REG_IMASK, SMSTA_XEN | SMSTA_MTN);
89 		wait_for_completion_timeout(&smbus->irq_completion, msecs_to_jiffies(100));
90 		reg_write(smbus, REG_IMASK, 0);
91 		status = reg_read(smbus, REG_SMSTA);
92 	} else {
93 		status = reg_read(smbus, REG_SMSTA);
94 		while (!(status & SMSTA_XEN) && timeout--) {
95 			msleep(1);
96 			status = reg_read(smbus, REG_SMSTA);
97 		}
98 	}
99 
100 	/* Got NACK? */
101 	if (status & SMSTA_MTN)
102 		return -ENXIO;
103 
104 	if (timeout < 0) {
105 		dev_warn(smbus->dev, "Timeout, status 0x%08x\n", status);
106 		reg_write(smbus, REG_SMSTA, status);
107 		return -ETIME;
108 	}
109 
110 	/* Clear XEN */
111 	reg_write(smbus, REG_SMSTA, SMSTA_XEN);
112 
113 	return 0;
114 }
115 
116 static int pasemi_i2c_xfer_msg(struct i2c_adapter *adapter,
117 			       struct i2c_msg *msg, int stop)
118 {
119 	struct pasemi_smbus *smbus = adapter->algo_data;
120 	int read, i, err;
121 	u32 rd;
122 
123 	read = msg->flags & I2C_M_RD ? 1 : 0;
124 
125 	TXFIFO_WR(smbus, MTXFIFO_START | i2c_8bit_addr_from_msg(msg));
126 
127 	if (read) {
128 		TXFIFO_WR(smbus, msg->len | MTXFIFO_READ |
129 				 (stop ? MTXFIFO_STOP : 0));
130 
131 		err = pasemi_smb_waitready(smbus);
132 		if (err)
133 			goto reset_out;
134 
135 		for (i = 0; i < msg->len; i++) {
136 			rd = RXFIFO_RD(smbus);
137 			if (rd & MRXFIFO_EMPTY) {
138 				err = -ENODATA;
139 				goto reset_out;
140 			}
141 			msg->buf[i] = rd & MRXFIFO_DATA_M;
142 		}
143 	} else {
144 		for (i = 0; i < msg->len - 1; i++)
145 			TXFIFO_WR(smbus, msg->buf[i]);
146 
147 		TXFIFO_WR(smbus, msg->buf[msg->len-1] |
148 			  (stop ? MTXFIFO_STOP : 0));
149 
150 		if (stop) {
151 			err = pasemi_smb_waitready(smbus);
152 			if (err)
153 				goto reset_out;
154 		}
155 	}
156 
157 	return 0;
158 
159  reset_out:
160 	pasemi_reset(smbus);
161 	return err;
162 }
163 
164 static int pasemi_i2c_xfer(struct i2c_adapter *adapter,
165 			   struct i2c_msg *msgs, int num)
166 {
167 	struct pasemi_smbus *smbus = adapter->algo_data;
168 	int ret, i;
169 
170 	pasemi_smb_clear(smbus);
171 
172 	ret = 0;
173 
174 	for (i = 0; i < num && !ret; i++)
175 		ret = pasemi_i2c_xfer_msg(adapter, &msgs[i], (i == (num - 1)));
176 
177 	return ret ? ret : num;
178 }
179 
180 static int pasemi_smb_xfer(struct i2c_adapter *adapter,
181 		u16 addr, unsigned short flags, char read_write, u8 command,
182 		int size, union i2c_smbus_data *data)
183 {
184 	struct pasemi_smbus *smbus = adapter->algo_data;
185 	unsigned int rd;
186 	int read_flag, err;
187 	int len = 0, i;
188 
189 	/* All our ops take 8-bit shifted addresses */
190 	addr <<= 1;
191 	read_flag = read_write == I2C_SMBUS_READ;
192 
193 	pasemi_smb_clear(smbus);
194 
195 	switch (size) {
196 	case I2C_SMBUS_QUICK:
197 		TXFIFO_WR(smbus, addr | read_flag | MTXFIFO_START |
198 			  MTXFIFO_STOP);
199 		break;
200 	case I2C_SMBUS_BYTE:
201 		TXFIFO_WR(smbus, addr | read_flag | MTXFIFO_START);
202 		if (read_write)
203 			TXFIFO_WR(smbus, 1 | MTXFIFO_STOP | MTXFIFO_READ);
204 		else
205 			TXFIFO_WR(smbus, MTXFIFO_STOP | command);
206 		break;
207 	case I2C_SMBUS_BYTE_DATA:
208 		TXFIFO_WR(smbus, addr | MTXFIFO_START);
209 		TXFIFO_WR(smbus, command);
210 		if (read_write) {
211 			TXFIFO_WR(smbus, addr | I2C_SMBUS_READ | MTXFIFO_START);
212 			TXFIFO_WR(smbus, 1 | MTXFIFO_READ | MTXFIFO_STOP);
213 		} else {
214 			TXFIFO_WR(smbus, MTXFIFO_STOP | data->byte);
215 		}
216 		break;
217 	case I2C_SMBUS_WORD_DATA:
218 		TXFIFO_WR(smbus, addr | MTXFIFO_START);
219 		TXFIFO_WR(smbus, command);
220 		if (read_write) {
221 			TXFIFO_WR(smbus, addr | I2C_SMBUS_READ | MTXFIFO_START);
222 			TXFIFO_WR(smbus, 2 | MTXFIFO_READ | MTXFIFO_STOP);
223 		} else {
224 			TXFIFO_WR(smbus, data->word & MTXFIFO_DATA_M);
225 			TXFIFO_WR(smbus, MTXFIFO_STOP | (data->word >> 8));
226 		}
227 		break;
228 	case I2C_SMBUS_BLOCK_DATA:
229 		TXFIFO_WR(smbus, addr | MTXFIFO_START);
230 		TXFIFO_WR(smbus, command);
231 		if (read_write) {
232 			TXFIFO_WR(smbus, addr | I2C_SMBUS_READ | MTXFIFO_START);
233 			TXFIFO_WR(smbus, 1 | MTXFIFO_READ);
234 			rd = RXFIFO_RD(smbus);
235 			len = min_t(u8, (rd & MRXFIFO_DATA_M),
236 				    I2C_SMBUS_BLOCK_MAX);
237 			TXFIFO_WR(smbus, len | MTXFIFO_READ |
238 					 MTXFIFO_STOP);
239 		} else {
240 			len = min_t(u8, data->block[0], I2C_SMBUS_BLOCK_MAX);
241 			TXFIFO_WR(smbus, len);
242 			for (i = 1; i < len; i++)
243 				TXFIFO_WR(smbus, data->block[i]);
244 			TXFIFO_WR(smbus, data->block[len] | MTXFIFO_STOP);
245 		}
246 		break;
247 	case I2C_SMBUS_PROC_CALL:
248 		read_write = I2C_SMBUS_READ;
249 		TXFIFO_WR(smbus, addr | MTXFIFO_START);
250 		TXFIFO_WR(smbus, command);
251 		TXFIFO_WR(smbus, data->word & MTXFIFO_DATA_M);
252 		TXFIFO_WR(smbus, (data->word >> 8) & MTXFIFO_DATA_M);
253 		TXFIFO_WR(smbus, addr | I2C_SMBUS_READ | MTXFIFO_START);
254 		TXFIFO_WR(smbus, 2 | MTXFIFO_STOP | MTXFIFO_READ);
255 		break;
256 	case I2C_SMBUS_BLOCK_PROC_CALL:
257 		len = min_t(u8, data->block[0], I2C_SMBUS_BLOCK_MAX - 1);
258 		read_write = I2C_SMBUS_READ;
259 		TXFIFO_WR(smbus, addr | MTXFIFO_START);
260 		TXFIFO_WR(smbus, command);
261 		TXFIFO_WR(smbus, len);
262 		for (i = 1; i <= len; i++)
263 			TXFIFO_WR(smbus, data->block[i]);
264 		TXFIFO_WR(smbus, addr | I2C_SMBUS_READ);
265 		TXFIFO_WR(smbus, MTXFIFO_READ | 1);
266 		rd = RXFIFO_RD(smbus);
267 		len = min_t(u8, (rd & MRXFIFO_DATA_M),
268 			    I2C_SMBUS_BLOCK_MAX - len);
269 		TXFIFO_WR(smbus, len | MTXFIFO_READ | MTXFIFO_STOP);
270 		break;
271 
272 	default:
273 		dev_warn(&adapter->dev, "Unsupported transaction %d\n", size);
274 		return -EINVAL;
275 	}
276 
277 	err = pasemi_smb_waitready(smbus);
278 	if (err)
279 		goto reset_out;
280 
281 	if (read_write == I2C_SMBUS_WRITE)
282 		return 0;
283 
284 	switch (size) {
285 	case I2C_SMBUS_BYTE:
286 	case I2C_SMBUS_BYTE_DATA:
287 		rd = RXFIFO_RD(smbus);
288 		if (rd & MRXFIFO_EMPTY) {
289 			err = -ENODATA;
290 			goto reset_out;
291 		}
292 		data->byte = rd & MRXFIFO_DATA_M;
293 		break;
294 	case I2C_SMBUS_WORD_DATA:
295 	case I2C_SMBUS_PROC_CALL:
296 		rd = RXFIFO_RD(smbus);
297 		if (rd & MRXFIFO_EMPTY) {
298 			err = -ENODATA;
299 			goto reset_out;
300 		}
301 		data->word = rd & MRXFIFO_DATA_M;
302 		rd = RXFIFO_RD(smbus);
303 		if (rd & MRXFIFO_EMPTY) {
304 			err = -ENODATA;
305 			goto reset_out;
306 		}
307 		data->word |= (rd & MRXFIFO_DATA_M) << 8;
308 		break;
309 	case I2C_SMBUS_BLOCK_DATA:
310 	case I2C_SMBUS_BLOCK_PROC_CALL:
311 		data->block[0] = len;
312 		for (i = 1; i <= len; i ++) {
313 			rd = RXFIFO_RD(smbus);
314 			if (rd & MRXFIFO_EMPTY) {
315 				err = -ENODATA;
316 				goto reset_out;
317 			}
318 			data->block[i] = rd & MRXFIFO_DATA_M;
319 		}
320 		break;
321 	}
322 
323 	return 0;
324 
325  reset_out:
326 	pasemi_reset(smbus);
327 	return err;
328 }
329 
330 static u32 pasemi_smb_func(struct i2c_adapter *adapter)
331 {
332 	return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
333 	       I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
334 	       I2C_FUNC_SMBUS_BLOCK_DATA | I2C_FUNC_SMBUS_PROC_CALL |
335 	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL | I2C_FUNC_I2C;
336 }
337 
338 static const struct i2c_algorithm smbus_algorithm = {
339 	.master_xfer	= pasemi_i2c_xfer,
340 	.smbus_xfer	= pasemi_smb_xfer,
341 	.functionality	= pasemi_smb_func,
342 };
343 
344 int pasemi_i2c_common_probe(struct pasemi_smbus *smbus)
345 {
346 	int error;
347 
348 	smbus->adapter.owner = THIS_MODULE;
349 	snprintf(smbus->adapter.name, sizeof(smbus->adapter.name),
350 		 "PA Semi SMBus adapter (%s)", dev_name(smbus->dev));
351 	smbus->adapter.algo = &smbus_algorithm;
352 	smbus->adapter.algo_data = smbus;
353 
354 	/* set up the sysfs linkage to our parent device */
355 	smbus->adapter.dev.parent = smbus->dev;
356 	smbus->use_irq = 0;
357 	init_completion(&smbus->irq_completion);
358 
359 	if (smbus->hw_rev != PASEMI_HW_REV_PCI)
360 		smbus->hw_rev = reg_read(smbus, REG_REV);
361 
362 	reg_write(smbus, REG_IMASK, 0);
363 
364 	pasemi_reset(smbus);
365 
366 	error = devm_i2c_add_adapter(smbus->dev, &smbus->adapter);
367 	if (error)
368 		return error;
369 
370 	return 0;
371 }
372 
373 irqreturn_t pasemi_irq_handler(int irq, void *dev_id)
374 {
375 	struct pasemi_smbus *smbus = dev_id;
376 
377 	reg_write(smbus, REG_IMASK, 0);
378 	complete(&smbus->irq_completion);
379 	return IRQ_HANDLED;
380 }
381