xref: /openbmc/u-boot/drivers/i2c/rcar_i2c.c (revision 2e8092d9)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * drivers/i2c/rcar_i2c.c
4  *
5  * Copyright (C) 2018 Marek Vasut <marek.vasut@gmail.com>
6  *
7  * Clock configuration based on Linux i2c-rcar.c:
8  * Copyright (C) 2014-15 Wolfram Sang <wsa@sang-engineering.com>
9  * Copyright (C) 2011-2015 Renesas Electronics Corporation
10  * Copyright (C) 2012-14 Renesas Solutions Corp.
11  *   Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
12  */
13 
14 #include <common.h>
15 #include <clk.h>
16 #include <dm.h>
17 #include <i2c.h>
18 #include <asm/io.h>
19 #include <wait_bit.h>
20 
21 #define RCAR_I2C_ICSCR			0x00 /* slave ctrl */
22 #define RCAR_I2C_ICMCR			0x04 /* master ctrl */
23 #define RCAR_I2C_ICMCR_MDBS		BIT(7) /* non-fifo mode switch */
24 #define RCAR_I2C_ICMCR_FSCL		BIT(6) /* override SCL pin */
25 #define RCAR_I2C_ICMCR_FSDA		BIT(5) /* override SDA pin */
26 #define RCAR_I2C_ICMCR_OBPC		BIT(4) /* override pins */
27 #define RCAR_I2C_ICMCR_MIE		BIT(3) /* master if enable */
28 #define RCAR_I2C_ICMCR_TSBE		BIT(2)
29 #define RCAR_I2C_ICMCR_FSB		BIT(1) /* force stop bit */
30 #define RCAR_I2C_ICMCR_ESG		BIT(0) /* enable start bit gen */
31 #define RCAR_I2C_ICSSR			0x08 /* slave status */
32 #define RCAR_I2C_ICMSR			0x0c /* master status */
33 #define RCAR_I2C_ICMSR_MASK		0x7f
34 #define RCAR_I2C_ICMSR_MNR		BIT(6) /* Nack */
35 #define RCAR_I2C_ICMSR_MAL		BIT(5) /* Arbitration lost */
36 #define RCAR_I2C_ICMSR_MST		BIT(4) /* Stop */
37 #define RCAR_I2C_ICMSR_MDE		BIT(3)
38 #define RCAR_I2C_ICMSR_MDT		BIT(2)
39 #define RCAR_I2C_ICMSR_MDR		BIT(1)
40 #define RCAR_I2C_ICMSR_MAT		BIT(0)
41 #define RCAR_I2C_ICSIER			0x10 /* slave irq enable */
42 #define RCAR_I2C_ICMIER			0x14 /* master irq enable */
43 #define RCAR_I2C_ICCCR			0x18 /* clock dividers */
44 #define RCAR_I2C_ICCCR_SCGD_OFF		3
45 #define RCAR_I2C_ICSAR			0x1c /* slave address */
46 #define RCAR_I2C_ICMAR			0x20 /* master address */
47 #define RCAR_I2C_ICRXD_ICTXD		0x24 /* data port */
48 /*
49  * First Bit Setup Cycle (Gen3).
50  * Defines 1st bit delay between SDA and SCL.
51  */
52 #define RCAR_I2C_ICFBSCR		0x38
53 #define RCAR_I2C_ICFBSCR_TCYC17		0x0f /* 17*Tcyc */
54 
55 
56 enum rcar_i2c_type {
57 	RCAR_I2C_TYPE_GEN2,
58 	RCAR_I2C_TYPE_GEN3,
59 };
60 
61 struct rcar_i2c_priv {
62 	void __iomem		*base;
63 	struct clk		clk;
64 	u32			intdelay;
65 	u32			icccr;
66 	enum rcar_i2c_type	type;
67 };
68 
rcar_i2c_finish(struct udevice * dev)69 static int rcar_i2c_finish(struct udevice *dev)
70 {
71 	struct rcar_i2c_priv *priv = dev_get_priv(dev);
72 	int ret;
73 
74 	ret = wait_for_bit_le32(priv->base + RCAR_I2C_ICMSR, RCAR_I2C_ICMSR_MST,
75 				true, 10, true);
76 
77 	writel(0, priv->base + RCAR_I2C_ICSSR);
78 	writel(0, priv->base + RCAR_I2C_ICMSR);
79 	writel(0, priv->base + RCAR_I2C_ICMCR);
80 
81 	return ret;
82 }
83 
rcar_i2c_recover(struct udevice * dev)84 static int rcar_i2c_recover(struct udevice *dev)
85 {
86 	struct rcar_i2c_priv *priv = dev_get_priv(dev);
87 	u32 mcr = RCAR_I2C_ICMCR_MDBS | RCAR_I2C_ICMCR_OBPC;
88 	u32 mcra = mcr | RCAR_I2C_ICMCR_FSDA;
89 	int i;
90 	u32 mstat;
91 
92 	/* Send 9 SCL pulses */
93 	for (i = 0; i < 9; i++) {
94 		writel(mcra | RCAR_I2C_ICMCR_FSCL, priv->base + RCAR_I2C_ICMCR);
95 		udelay(5);
96 		writel(mcra, priv->base + RCAR_I2C_ICMCR);
97 		udelay(5);
98 	}
99 
100 	/* Send stop condition */
101 	udelay(5);
102 	writel(mcra, priv->base + RCAR_I2C_ICMCR);
103 	udelay(5);
104 	writel(mcr, priv->base + RCAR_I2C_ICMCR);
105 	udelay(5);
106 	writel(mcr | RCAR_I2C_ICMCR_FSCL, priv->base + RCAR_I2C_ICMCR);
107 	udelay(5);
108 	writel(mcra | RCAR_I2C_ICMCR_FSCL, priv->base + RCAR_I2C_ICMCR);
109 	udelay(5);
110 
111 	mstat = readl(priv->base + RCAR_I2C_ICMSR);
112 	return mstat & RCAR_I2C_ICMCR_FSDA ? -EBUSY : 0;
113 }
114 
rcar_i2c_set_addr(struct udevice * dev,u8 chip,u8 read)115 static int rcar_i2c_set_addr(struct udevice *dev, u8 chip, u8 read)
116 {
117 	struct rcar_i2c_priv *priv = dev_get_priv(dev);
118 	u32 mask = RCAR_I2C_ICMSR_MAT |
119 		   (read ? RCAR_I2C_ICMSR_MDR : RCAR_I2C_ICMSR_MDE);
120 	int ret;
121 
122 	writel(0, priv->base + RCAR_I2C_ICMIER);
123 	writel(RCAR_I2C_ICMCR_MDBS, priv->base + RCAR_I2C_ICMCR);
124 	writel(0, priv->base + RCAR_I2C_ICMSR);
125 	writel(priv->icccr, priv->base + RCAR_I2C_ICCCR);
126 
127 	/* Wait for the bus */
128 	ret = wait_for_bit_le32(priv->base + RCAR_I2C_ICMCR,
129 				RCAR_I2C_ICMCR_FSDA, false, 2, true);
130 	if (ret) {
131 		if (rcar_i2c_recover(dev)) {
132 			dev_err(dev, "Bus busy, aborting\n");
133 			return ret;
134 		}
135 	}
136 
137 	writel((chip << 1) | read, priv->base + RCAR_I2C_ICMAR);
138 	/* Reset */
139 	writel(RCAR_I2C_ICMCR_MDBS | RCAR_I2C_ICMCR_MIE | RCAR_I2C_ICMCR_ESG,
140 	       priv->base + RCAR_I2C_ICMCR);
141 	/* Clear Status */
142 	writel(0, priv->base + RCAR_I2C_ICMSR);
143 
144 	ret = wait_for_bit_le32(priv->base + RCAR_I2C_ICMSR, mask,
145 				true, 100, true);
146 	if (ret)
147 		return ret;
148 
149 	/* Check NAK */
150 	if (readl(priv->base + RCAR_I2C_ICMSR) & RCAR_I2C_ICMSR_MNR)
151 		return -EREMOTEIO;
152 
153 	return 0;
154 }
155 
rcar_i2c_read_common(struct udevice * dev,struct i2c_msg * msg)156 static int rcar_i2c_read_common(struct udevice *dev, struct i2c_msg *msg)
157 {
158 	struct rcar_i2c_priv *priv = dev_get_priv(dev);
159 	u32 icmcr = RCAR_I2C_ICMCR_MDBS | RCAR_I2C_ICMCR_MIE;
160 	int i, ret = -EREMOTEIO;
161 
162 	for (i = 0; i < msg->len; i++) {
163 		if (msg->len - 1 == i)
164 			icmcr |= RCAR_I2C_ICMCR_FSB;
165 
166 		writel(icmcr, priv->base + RCAR_I2C_ICMCR);
167 		writel((u32)~RCAR_I2C_ICMSR_MDR, priv->base + RCAR_I2C_ICMSR);
168 
169 		ret = wait_for_bit_le32(priv->base + RCAR_I2C_ICMSR,
170 					RCAR_I2C_ICMSR_MDR, true, 100, true);
171 		if (ret)
172 			return ret;
173 
174 		msg->buf[i] = readl(priv->base + RCAR_I2C_ICRXD_ICTXD) & 0xff;
175 	}
176 
177 	writel((u32)~RCAR_I2C_ICMSR_MDR, priv->base + RCAR_I2C_ICMSR);
178 
179 	return rcar_i2c_finish(dev);
180 }
181 
rcar_i2c_write_common(struct udevice * dev,struct i2c_msg * msg)182 static int rcar_i2c_write_common(struct udevice *dev, struct i2c_msg *msg)
183 {
184 	struct rcar_i2c_priv *priv = dev_get_priv(dev);
185 	u32 icmcr = RCAR_I2C_ICMCR_MDBS | RCAR_I2C_ICMCR_MIE;
186 	int i, ret = -EREMOTEIO;
187 
188 	for (i = 0; i < msg->len; i++) {
189 		writel(msg->buf[i], priv->base + RCAR_I2C_ICRXD_ICTXD);
190 		writel(icmcr, priv->base + RCAR_I2C_ICMCR);
191 		writel((u32)~RCAR_I2C_ICMSR_MDE, priv->base + RCAR_I2C_ICMSR);
192 
193 		ret = wait_for_bit_le32(priv->base + RCAR_I2C_ICMSR,
194 					RCAR_I2C_ICMSR_MDE, true, 100, true);
195 		if (ret)
196 			return ret;
197 	}
198 
199 	writel((u32)~RCAR_I2C_ICMSR_MDE, priv->base + RCAR_I2C_ICMSR);
200 	icmcr |= RCAR_I2C_ICMCR_FSB;
201 	writel(icmcr, priv->base + RCAR_I2C_ICMCR);
202 
203 	return rcar_i2c_finish(dev);
204 }
205 
rcar_i2c_xfer(struct udevice * dev,struct i2c_msg * msg,int nmsgs)206 static int rcar_i2c_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs)
207 {
208 	int ret;
209 
210 	for (; nmsgs > 0; nmsgs--, msg++) {
211 		ret = rcar_i2c_set_addr(dev, msg->addr, 1);
212 		if (ret)
213 			return ret;
214 
215 		if (msg->flags & I2C_M_RD)
216 			ret = rcar_i2c_read_common(dev, msg);
217 		else
218 			ret = rcar_i2c_write_common(dev, msg);
219 
220 		if (ret)
221 			return ret;
222 	}
223 
224 	return 0;
225 }
226 
rcar_i2c_probe_chip(struct udevice * dev,uint addr,uint flags)227 static int rcar_i2c_probe_chip(struct udevice *dev, uint addr, uint flags)
228 {
229 	struct rcar_i2c_priv *priv = dev_get_priv(dev);
230 	int ret;
231 
232 	/* Ignore address 0, slave address */
233 	if (addr == 0)
234 		return -EINVAL;
235 
236 	ret = rcar_i2c_set_addr(dev, addr, 1);
237 	writel(0, priv->base + RCAR_I2C_ICMSR);
238 	return ret;
239 }
240 
rcar_i2c_set_speed(struct udevice * dev,uint bus_freq_hz)241 static int rcar_i2c_set_speed(struct udevice *dev, uint bus_freq_hz)
242 {
243 	struct rcar_i2c_priv *priv = dev_get_priv(dev);
244 	u32 scgd, cdf, round, ick, sum, scl;
245 	unsigned long rate;
246 
247 	/*
248 	 * calculate SCL clock
249 	 * see
250 	 *	ICCCR
251 	 *
252 	 * ick	= clkp / (1 + CDF)
253 	 * SCL	= ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
254 	 *
255 	 * ick  : I2C internal clock < 20 MHz
256 	 * ticf : I2C SCL falling time
257 	 * tr   : I2C SCL rising  time
258 	 * intd : LSI internal delay
259 	 * clkp : peripheral_clk
260 	 * F[]  : integer up-valuation
261 	 */
262 	rate = clk_get_rate(&priv->clk);
263 	cdf = rate / 20000000;
264 	if (cdf >= 8) {
265 		dev_err(dev, "Input clock %lu too high\n", rate);
266 		return -EIO;
267 	}
268 	ick = rate / (cdf + 1);
269 
270 	/*
271 	 * it is impossible to calculate large scale
272 	 * number on u32. separate it
273 	 *
274 	 * F[(ticf + tr + intd) * ick] with sum = (ticf + tr + intd)
275 	 *  = F[sum * ick / 1000000000]
276 	 *  = F[(ick / 1000000) * sum / 1000]
277 	 */
278 	sum = 35 + 200 + priv->intdelay;
279 	round = (ick + 500000) / 1000000 * sum;
280 	round = (round + 500) / 1000;
281 
282 	/*
283 	 * SCL	= ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
284 	 *
285 	 * Calculation result (= SCL) should be less than
286 	 * bus_speed for hardware safety
287 	 *
288 	 * We could use something along the lines of
289 	 *	div = ick / (bus_speed + 1) + 1;
290 	 *	scgd = (div - 20 - round + 7) / 8;
291 	 *	scl = ick / (20 + (scgd * 8) + round);
292 	 * (not fully verified) but that would get pretty involved
293 	 */
294 	for (scgd = 0; scgd < 0x40; scgd++) {
295 		scl = ick / (20 + (scgd * 8) + round);
296 		if (scl <= bus_freq_hz)
297 			goto scgd_find;
298 	}
299 	dev_err(dev, "it is impossible to calculate best SCL\n");
300 	return -EIO;
301 
302 scgd_find:
303 	dev_dbg(dev, "clk %d/%d(%lu), round %u, CDF:0x%x, SCGD: 0x%x\n",
304 		scl, bus_freq_hz, clk_get_rate(&priv->clk), round, cdf, scgd);
305 
306 	priv->icccr = (scgd << RCAR_I2C_ICCCR_SCGD_OFF) | cdf;
307 	writel(priv->icccr, priv->base + RCAR_I2C_ICCCR);
308 
309 	if (priv->type == RCAR_I2C_TYPE_GEN3) {
310 		/* Set SCL/SDA delay */
311 		writel(RCAR_I2C_ICFBSCR_TCYC17, priv->base + RCAR_I2C_ICFBSCR);
312 	}
313 
314 	return 0;
315 }
316 
rcar_i2c_probe(struct udevice * dev)317 static int rcar_i2c_probe(struct udevice *dev)
318 {
319 	struct rcar_i2c_priv *priv = dev_get_priv(dev);
320 	int ret;
321 
322 	priv->base = dev_read_addr_ptr(dev);
323 	priv->intdelay = dev_read_u32_default(dev,
324 					      "i2c-scl-internal-delay-ns", 5);
325 	priv->type = dev_get_driver_data(dev);
326 
327 	ret = clk_get_by_index(dev, 0, &priv->clk);
328 	if (ret)
329 		return ret;
330 
331 	ret = clk_enable(&priv->clk);
332 	if (ret)
333 		return ret;
334 
335 	/* reset slave mode */
336 	writel(0, priv->base + RCAR_I2C_ICSIER);
337 	writel(0, priv->base + RCAR_I2C_ICSAR);
338 	writel(0, priv->base + RCAR_I2C_ICSCR);
339 	writel(0, priv->base + RCAR_I2C_ICSSR);
340 
341 	/* reset master mode */
342 	writel(0, priv->base + RCAR_I2C_ICMIER);
343 	writel(0, priv->base + RCAR_I2C_ICMCR);
344 	writel(0, priv->base + RCAR_I2C_ICMSR);
345 	writel(0, priv->base + RCAR_I2C_ICMAR);
346 
347 	ret = rcar_i2c_set_speed(dev, 100000);
348 	if (ret)
349 		clk_disable(&priv->clk);
350 
351 	return ret;
352 }
353 
354 static const struct dm_i2c_ops rcar_i2c_ops = {
355 	.xfer		= rcar_i2c_xfer,
356 	.probe_chip	= rcar_i2c_probe_chip,
357 	.set_bus_speed	= rcar_i2c_set_speed,
358 };
359 
360 static const struct udevice_id rcar_i2c_ids[] = {
361 	{ .compatible = "renesas,rcar-gen2-i2c", .data = RCAR_I2C_TYPE_GEN2 },
362 	{ .compatible = "renesas,rcar-gen3-i2c", .data = RCAR_I2C_TYPE_GEN3 },
363 	{ }
364 };
365 
366 U_BOOT_DRIVER(i2c_rcar) = {
367 	.name		= "i2c_rcar",
368 	.id		= UCLASS_I2C,
369 	.of_match	= rcar_i2c_ids,
370 	.probe		= rcar_i2c_probe,
371 	.priv_auto_alloc_size = sizeof(struct rcar_i2c_priv),
372 	.ops		= &rcar_i2c_ops,
373 };
374