xref: /linux/drivers/i2c/busses/i2c-axxia.c (revision c79c3c34f75d72a066e292b10aa50fc758c97c89)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * This driver implements I2C master functionality using the LSI API2C
4  * controller.
5  *
6  * NOTE: The controller has a limitation in that it can only do transfers of
7  * maximum 255 bytes at a time. If a larger transfer is attempted, error code
8  * (-EINVAL) is returned.
9  */
10 #include <linux/clk.h>
11 #include <linux/clkdev.h>
12 #include <linux/delay.h>
13 #include <linux/err.h>
14 #include <linux/i2c.h>
15 #include <linux/init.h>
16 #include <linux/interrupt.h>
17 #include <linux/module.h>
18 #include <linux/io.h>
19 #include <linux/kernel.h>
20 #include <linux/platform_device.h>
21 
22 #define SCL_WAIT_TIMEOUT_NS 25000000
23 #define I2C_XFER_TIMEOUT    (msecs_to_jiffies(250))
24 #define I2C_STOP_TIMEOUT    (msecs_to_jiffies(100))
25 #define FIFO_SIZE           8
26 #define SEQ_LEN             2
27 
28 #define GLOBAL_CONTROL		0x00
29 #define   GLOBAL_MST_EN         BIT(0)
30 #define   GLOBAL_SLV_EN         BIT(1)
31 #define   GLOBAL_IBML_EN        BIT(2)
32 #define INTERRUPT_STATUS	0x04
33 #define INTERRUPT_ENABLE	0x08
34 #define   INT_SLV               BIT(1)
35 #define   INT_MST               BIT(0)
36 #define WAIT_TIMER_CONTROL	0x0c
37 #define   WT_EN			BIT(15)
38 #define   WT_VALUE(_x)		((_x) & 0x7fff)
39 #define IBML_TIMEOUT		0x10
40 #define IBML_LOW_MEXT		0x14
41 #define IBML_LOW_SEXT		0x18
42 #define TIMER_CLOCK_DIV		0x1c
43 #define I2C_BUS_MONITOR		0x20
44 #define   BM_SDAC		BIT(3)
45 #define   BM_SCLC		BIT(2)
46 #define   BM_SDAS		BIT(1)
47 #define   BM_SCLS		BIT(0)
48 #define SOFT_RESET		0x24
49 #define MST_COMMAND		0x28
50 #define   CMD_BUSY		(1<<3)
51 #define   CMD_MANUAL		(0x00 | CMD_BUSY)
52 #define   CMD_AUTO		(0x01 | CMD_BUSY)
53 #define   CMD_SEQUENCE		(0x02 | CMD_BUSY)
54 #define MST_RX_XFER		0x2c
55 #define MST_TX_XFER		0x30
56 #define MST_ADDR_1		0x34
57 #define MST_ADDR_2		0x38
58 #define MST_DATA		0x3c
59 #define MST_TX_FIFO		0x40
60 #define MST_RX_FIFO		0x44
61 #define MST_INT_ENABLE		0x48
62 #define MST_INT_STATUS		0x4c
63 #define   MST_STATUS_RFL	(1 << 13) /* RX FIFO serivce */
64 #define   MST_STATUS_TFL	(1 << 12) /* TX FIFO service */
65 #define   MST_STATUS_SNS	(1 << 11) /* Manual mode done */
66 #define   MST_STATUS_SS		(1 << 10) /* Automatic mode done */
67 #define   MST_STATUS_SCC	(1 << 9)  /* Stop complete */
68 #define   MST_STATUS_IP		(1 << 8)  /* Invalid parameter */
69 #define   MST_STATUS_TSS	(1 << 7)  /* Timeout */
70 #define   MST_STATUS_AL		(1 << 6)  /* Arbitration lost */
71 #define   MST_STATUS_ND		(1 << 5)  /* NAK on data phase */
72 #define   MST_STATUS_NA		(1 << 4)  /* NAK on address phase */
73 #define   MST_STATUS_NAK	(MST_STATUS_NA | \
74 				 MST_STATUS_ND)
75 #define   MST_STATUS_ERR	(MST_STATUS_NAK | \
76 				 MST_STATUS_AL  | \
77 				 MST_STATUS_IP)
78 #define MST_TX_BYTES_XFRD	0x50
79 #define MST_RX_BYTES_XFRD	0x54
80 #define SLV_ADDR_DEC_CTL	0x58
81 #define   SLV_ADDR_DEC_GCE	BIT(0)  /* ACK to General Call Address from own master (loopback) */
82 #define   SLV_ADDR_DEC_OGCE	BIT(1)  /* ACK to General Call Address from external masters */
83 #define   SLV_ADDR_DEC_SA1E	BIT(2)  /* ACK to addr_1 enabled */
84 #define   SLV_ADDR_DEC_SA1M	BIT(3)  /* 10-bit addressing for addr_1 enabled */
85 #define   SLV_ADDR_DEC_SA2E	BIT(4)  /* ACK to addr_2 enabled */
86 #define   SLV_ADDR_DEC_SA2M	BIT(5)  /* 10-bit addressing for addr_2 enabled */
87 #define SLV_ADDR_1		0x5c
88 #define SLV_ADDR_2		0x60
89 #define SLV_RX_CTL		0x64
90 #define   SLV_RX_ACSA1		BIT(0)  /* Generate ACK for writes to addr_1 */
91 #define   SLV_RX_ACSA2		BIT(1)  /* Generate ACK for writes to addr_2 */
92 #define   SLV_RX_ACGCA		BIT(2)  /* ACK data phase transfers to General Call Address */
93 #define SLV_DATA		0x68
94 #define SLV_RX_FIFO		0x6c
95 #define   SLV_FIFO_DV1		BIT(0)  /* Data Valid for addr_1 */
96 #define   SLV_FIFO_DV2		BIT(1)  /* Data Valid for addr_2 */
97 #define   SLV_FIFO_AS		BIT(2)  /* (N)ACK Sent */
98 #define   SLV_FIFO_TNAK		BIT(3)  /* Timeout NACK */
99 #define   SLV_FIFO_STRC		BIT(4)  /* First byte after start condition received */
100 #define   SLV_FIFO_RSC		BIT(5)  /* Repeated Start Condition */
101 #define   SLV_FIFO_STPC		BIT(6)  /* Stop Condition */
102 #define   SLV_FIFO_DV		(SLV_FIFO_DV1 | SLV_FIFO_DV2)
103 #define SLV_INT_ENABLE		0x70
104 #define SLV_INT_STATUS		0x74
105 #define   SLV_STATUS_RFH	BIT(0)  /* FIFO service */
106 #define   SLV_STATUS_WTC	BIT(1)  /* Write transfer complete */
107 #define   SLV_STATUS_SRS1	BIT(2)  /* Slave read from addr 1 */
108 #define   SLV_STATUS_SRRS1	BIT(3)  /* Repeated start from addr 1 */
109 #define   SLV_STATUS_SRND1	BIT(4)  /* Read request not following start condition */
110 #define   SLV_STATUS_SRC1	BIT(5)  /* Read canceled */
111 #define   SLV_STATUS_SRAT1	BIT(6)  /* Slave Read timed out */
112 #define   SLV_STATUS_SRDRE1	BIT(7)  /* Data written after timed out */
113 #define SLV_READ_DUMMY		0x78
114 #define SCL_HIGH_PERIOD		0x80
115 #define SCL_LOW_PERIOD		0x84
116 #define SPIKE_FLTR_LEN		0x88
117 #define SDA_SETUP_TIME		0x8c
118 #define SDA_HOLD_TIME		0x90
119 
120 /**
121  * axxia_i2c_dev - I2C device context
122  * @base: pointer to register struct
123  * @msg: pointer to current message
124  * @msg_r: pointer to current read message (sequence transfer)
125  * @msg_xfrd: number of bytes transferred in tx_fifo
126  * @msg_xfrd_r: number of bytes transferred in rx_fifo
127  * @msg_err: error code for completed message
128  * @msg_complete: xfer completion object
129  * @dev: device reference
130  * @adapter: core i2c abstraction
131  * @i2c_clk: clock reference for i2c input clock
132  * @bus_clk_rate: current i2c bus clock rate
133  * @last: a flag indicating is this is last message in transfer
134  */
135 struct axxia_i2c_dev {
136 	void __iomem *base;
137 	struct i2c_msg *msg;
138 	struct i2c_msg *msg_r;
139 	size_t msg_xfrd;
140 	size_t msg_xfrd_r;
141 	int msg_err;
142 	struct completion msg_complete;
143 	struct device *dev;
144 	struct i2c_adapter adapter;
145 	struct clk *i2c_clk;
146 	u32 bus_clk_rate;
147 	bool last;
148 	struct i2c_client *slave;
149 	int irq;
150 };
151 
152 static void i2c_int_disable(struct axxia_i2c_dev *idev, u32 mask)
153 {
154 	u32 int_en;
155 
156 	int_en = readl(idev->base + MST_INT_ENABLE);
157 	writel(int_en & ~mask, idev->base + MST_INT_ENABLE);
158 }
159 
160 static void i2c_int_enable(struct axxia_i2c_dev *idev, u32 mask)
161 {
162 	u32 int_en;
163 
164 	int_en = readl(idev->base + MST_INT_ENABLE);
165 	writel(int_en | mask, idev->base + MST_INT_ENABLE);
166 }
167 
168 /**
169  * ns_to_clk - Convert time (ns) to clock cycles for the given clock frequency.
170  */
171 static u32 ns_to_clk(u64 ns, u32 clk_mhz)
172 {
173 	return div_u64(ns * clk_mhz, 1000);
174 }
175 
176 static int axxia_i2c_init(struct axxia_i2c_dev *idev)
177 {
178 	u32 divisor = clk_get_rate(idev->i2c_clk) / idev->bus_clk_rate;
179 	u32 clk_mhz = clk_get_rate(idev->i2c_clk) / 1000000;
180 	u32 t_setup;
181 	u32 t_high, t_low;
182 	u32 tmo_clk;
183 	u32 prescale;
184 	unsigned long timeout;
185 
186 	dev_dbg(idev->dev, "rate=%uHz per_clk=%uMHz -> ratio=1:%u\n",
187 		idev->bus_clk_rate, clk_mhz, divisor);
188 
189 	/* Reset controller */
190 	writel(0x01, idev->base + SOFT_RESET);
191 	timeout = jiffies + msecs_to_jiffies(100);
192 	while (readl(idev->base + SOFT_RESET) & 1) {
193 		if (time_after(jiffies, timeout)) {
194 			dev_warn(idev->dev, "Soft reset failed\n");
195 			break;
196 		}
197 	}
198 
199 	/* Enable Master Mode */
200 	writel(0x1, idev->base + GLOBAL_CONTROL);
201 
202 	if (idev->bus_clk_rate <= I2C_MAX_STANDARD_MODE_FREQ) {
203 		/* Standard mode SCL 50/50, tSU:DAT = 250 ns */
204 		t_high = divisor * 1 / 2;
205 		t_low = divisor * 1 / 2;
206 		t_setup = ns_to_clk(250, clk_mhz);
207 	} else {
208 		/* Fast mode SCL 33/66, tSU:DAT = 100 ns */
209 		t_high = divisor * 1 / 3;
210 		t_low = divisor * 2 / 3;
211 		t_setup = ns_to_clk(100, clk_mhz);
212 	}
213 
214 	/* SCL High Time */
215 	writel(t_high, idev->base + SCL_HIGH_PERIOD);
216 	/* SCL Low Time */
217 	writel(t_low, idev->base + SCL_LOW_PERIOD);
218 	/* SDA Setup Time */
219 	writel(t_setup, idev->base + SDA_SETUP_TIME);
220 	/* SDA Hold Time, 300ns */
221 	writel(ns_to_clk(300, clk_mhz), idev->base + SDA_HOLD_TIME);
222 	/* Filter <50ns spikes */
223 	writel(ns_to_clk(50, clk_mhz), idev->base + SPIKE_FLTR_LEN);
224 
225 	/* Configure Time-Out Registers */
226 	tmo_clk = ns_to_clk(SCL_WAIT_TIMEOUT_NS, clk_mhz);
227 
228 	/* Find prescaler value that makes tmo_clk fit in 15-bits counter. */
229 	for (prescale = 0; prescale < 15; ++prescale) {
230 		if (tmo_clk <= 0x7fff)
231 			break;
232 		tmo_clk >>= 1;
233 	}
234 	if (tmo_clk > 0x7fff)
235 		tmo_clk = 0x7fff;
236 
237 	/* Prescale divider (log2) */
238 	writel(prescale, idev->base + TIMER_CLOCK_DIV);
239 	/* Timeout in divided clocks */
240 	writel(WT_EN | WT_VALUE(tmo_clk), idev->base + WAIT_TIMER_CONTROL);
241 
242 	/* Mask all master interrupt bits */
243 	i2c_int_disable(idev, ~0);
244 
245 	/* Interrupt enable */
246 	writel(0x01, idev->base + INTERRUPT_ENABLE);
247 
248 	return 0;
249 }
250 
251 static int i2c_m_rd(const struct i2c_msg *msg)
252 {
253 	return (msg->flags & I2C_M_RD) != 0;
254 }
255 
256 static int i2c_m_ten(const struct i2c_msg *msg)
257 {
258 	return (msg->flags & I2C_M_TEN) != 0;
259 }
260 
261 static int i2c_m_recv_len(const struct i2c_msg *msg)
262 {
263 	return (msg->flags & I2C_M_RECV_LEN) != 0;
264 }
265 
266 /**
267  * axxia_i2c_empty_rx_fifo - Fetch data from RX FIFO and update SMBus block
268  * transfer length if this is the first byte of such a transfer.
269  */
270 static int axxia_i2c_empty_rx_fifo(struct axxia_i2c_dev *idev)
271 {
272 	struct i2c_msg *msg = idev->msg_r;
273 	size_t rx_fifo_avail = readl(idev->base + MST_RX_FIFO);
274 	int bytes_to_transfer = min(rx_fifo_avail, msg->len - idev->msg_xfrd_r);
275 
276 	while (bytes_to_transfer-- > 0) {
277 		int c = readl(idev->base + MST_DATA);
278 
279 		if (idev->msg_xfrd_r == 0 && i2c_m_recv_len(msg)) {
280 			/*
281 			 * Check length byte for SMBus block read
282 			 */
283 			if (c <= 0 || c > I2C_SMBUS_BLOCK_MAX) {
284 				idev->msg_err = -EPROTO;
285 				i2c_int_disable(idev, ~MST_STATUS_TSS);
286 				complete(&idev->msg_complete);
287 				break;
288 			}
289 			msg->len = 1 + c;
290 			writel(msg->len, idev->base + MST_RX_XFER);
291 		}
292 		msg->buf[idev->msg_xfrd_r++] = c;
293 	}
294 
295 	return 0;
296 }
297 
298 /**
299  * axxia_i2c_fill_tx_fifo - Fill TX FIFO from current message buffer.
300  * @return: Number of bytes left to transfer.
301  */
302 static int axxia_i2c_fill_tx_fifo(struct axxia_i2c_dev *idev)
303 {
304 	struct i2c_msg *msg = idev->msg;
305 	size_t tx_fifo_avail = FIFO_SIZE - readl(idev->base + MST_TX_FIFO);
306 	int bytes_to_transfer = min(tx_fifo_avail, msg->len - idev->msg_xfrd);
307 	int ret = msg->len - idev->msg_xfrd - bytes_to_transfer;
308 
309 	while (bytes_to_transfer-- > 0)
310 		writel(msg->buf[idev->msg_xfrd++], idev->base + MST_DATA);
311 
312 	return ret;
313 }
314 
315 static void axxia_i2c_slv_fifo_event(struct axxia_i2c_dev *idev)
316 {
317 	u32 fifo_status = readl(idev->base + SLV_RX_FIFO);
318 	u8 val;
319 
320 	dev_dbg(idev->dev, "slave irq fifo_status=0x%x\n", fifo_status);
321 
322 	if (fifo_status & SLV_FIFO_DV1) {
323 		if (fifo_status & SLV_FIFO_STRC)
324 			i2c_slave_event(idev->slave,
325 					I2C_SLAVE_WRITE_REQUESTED, &val);
326 
327 		val = readl(idev->base + SLV_DATA);
328 		i2c_slave_event(idev->slave, I2C_SLAVE_WRITE_RECEIVED, &val);
329 	}
330 	if (fifo_status & SLV_FIFO_STPC) {
331 		readl(idev->base + SLV_DATA); /* dummy read */
332 		i2c_slave_event(idev->slave, I2C_SLAVE_STOP, &val);
333 	}
334 	if (fifo_status & SLV_FIFO_RSC)
335 		readl(idev->base + SLV_DATA); /* dummy read */
336 }
337 
338 static irqreturn_t axxia_i2c_slv_isr(struct axxia_i2c_dev *idev)
339 {
340 	u32 status = readl(idev->base + SLV_INT_STATUS);
341 	u8 val;
342 
343 	dev_dbg(idev->dev, "slave irq status=0x%x\n", status);
344 
345 	if (status & SLV_STATUS_RFH)
346 		axxia_i2c_slv_fifo_event(idev);
347 	if (status & SLV_STATUS_SRS1) {
348 		i2c_slave_event(idev->slave, I2C_SLAVE_READ_REQUESTED, &val);
349 		writel(val, idev->base + SLV_DATA);
350 	}
351 	if (status & SLV_STATUS_SRND1) {
352 		i2c_slave_event(idev->slave, I2C_SLAVE_READ_PROCESSED, &val);
353 		writel(val, idev->base + SLV_DATA);
354 	}
355 	if (status & SLV_STATUS_SRC1)
356 		i2c_slave_event(idev->slave, I2C_SLAVE_STOP, &val);
357 
358 	writel(INT_SLV, idev->base + INTERRUPT_STATUS);
359 	return IRQ_HANDLED;
360 }
361 
362 static irqreturn_t axxia_i2c_isr(int irq, void *_dev)
363 {
364 	struct axxia_i2c_dev *idev = _dev;
365 	irqreturn_t ret = IRQ_NONE;
366 	u32 status;
367 
368 	status = readl(idev->base + INTERRUPT_STATUS);
369 
370 	if (status & INT_SLV)
371 		ret = axxia_i2c_slv_isr(idev);
372 	if (!(status & INT_MST))
373 		return ret;
374 
375 	/* Read interrupt status bits */
376 	status = readl(idev->base + MST_INT_STATUS);
377 
378 	if (!idev->msg) {
379 		dev_warn(idev->dev, "unexpected interrupt\n");
380 		goto out;
381 	}
382 
383 	/* RX FIFO needs service? */
384 	if (i2c_m_rd(idev->msg_r) && (status & MST_STATUS_RFL))
385 		axxia_i2c_empty_rx_fifo(idev);
386 
387 	/* TX FIFO needs service? */
388 	if (!i2c_m_rd(idev->msg) && (status & MST_STATUS_TFL)) {
389 		if (axxia_i2c_fill_tx_fifo(idev) == 0)
390 			i2c_int_disable(idev, MST_STATUS_TFL);
391 	}
392 
393 	if (unlikely(status & MST_STATUS_ERR)) {
394 		/* Transfer error */
395 		i2c_int_disable(idev, ~0);
396 		if (status & MST_STATUS_AL)
397 			idev->msg_err = -EAGAIN;
398 		else if (status & MST_STATUS_NAK)
399 			idev->msg_err = -ENXIO;
400 		else
401 			idev->msg_err = -EIO;
402 		dev_dbg(idev->dev, "error %#x, addr=%#x rx=%u/%u tx=%u/%u\n",
403 			status,
404 			idev->msg->addr,
405 			readl(idev->base + MST_RX_BYTES_XFRD),
406 			readl(idev->base + MST_RX_XFER),
407 			readl(idev->base + MST_TX_BYTES_XFRD),
408 			readl(idev->base + MST_TX_XFER));
409 		complete(&idev->msg_complete);
410 	} else if (status & MST_STATUS_SCC) {
411 		/* Stop completed */
412 		i2c_int_disable(idev, ~MST_STATUS_TSS);
413 		complete(&idev->msg_complete);
414 	} else if (status & (MST_STATUS_SNS | MST_STATUS_SS)) {
415 		/* Transfer done */
416 		int mask = idev->last ? ~0 : ~MST_STATUS_TSS;
417 
418 		i2c_int_disable(idev, mask);
419 		if (i2c_m_rd(idev->msg_r) && idev->msg_xfrd_r < idev->msg_r->len)
420 			axxia_i2c_empty_rx_fifo(idev);
421 		complete(&idev->msg_complete);
422 	} else if (status & MST_STATUS_TSS) {
423 		/* Transfer timeout */
424 		idev->msg_err = -ETIMEDOUT;
425 		i2c_int_disable(idev, ~MST_STATUS_TSS);
426 		complete(&idev->msg_complete);
427 	}
428 
429 out:
430 	/* Clear interrupt */
431 	writel(INT_MST, idev->base + INTERRUPT_STATUS);
432 
433 	return IRQ_HANDLED;
434 }
435 
436 static void axxia_i2c_set_addr(struct axxia_i2c_dev *idev, struct i2c_msg *msg)
437 {
438 	u32 addr_1, addr_2;
439 
440 	if (i2c_m_ten(msg)) {
441 		/* 10-bit address
442 		 *   addr_1: 5'b11110 | addr[9:8] | (R/nW)
443 		 *   addr_2: addr[7:0]
444 		 */
445 		addr_1 = 0xF0 | ((msg->addr >> 7) & 0x06);
446 		if (i2c_m_rd(msg))
447 			addr_1 |= 1;	/* Set the R/nW bit of the address */
448 		addr_2 = msg->addr & 0xFF;
449 	} else {
450 		/* 7-bit address
451 		 *   addr_1: addr[6:0] | (R/nW)
452 		 *   addr_2: dont care
453 		 */
454 		addr_1 = i2c_8bit_addr_from_msg(msg);
455 		addr_2 = 0;
456 	}
457 
458 	writel(addr_1, idev->base + MST_ADDR_1);
459 	writel(addr_2, idev->base + MST_ADDR_2);
460 }
461 
462 /* The NAK interrupt will be sent _before_ issuing STOP command
463  * so the controller might still be busy processing it. No
464  * interrupt will be sent at the end so we have to poll for it
465  */
466 static int axxia_i2c_handle_seq_nak(struct axxia_i2c_dev *idev)
467 {
468 	unsigned long timeout = jiffies + I2C_XFER_TIMEOUT;
469 
470 	do {
471 		if ((readl(idev->base + MST_COMMAND) & CMD_BUSY) == 0)
472 			return 0;
473 		usleep_range(1, 100);
474 	} while (time_before(jiffies, timeout));
475 
476 	return -ETIMEDOUT;
477 }
478 
479 static int axxia_i2c_xfer_seq(struct axxia_i2c_dev *idev, struct i2c_msg msgs[])
480 {
481 	u32 int_mask = MST_STATUS_ERR | MST_STATUS_SS | MST_STATUS_RFL;
482 	u32 rlen = i2c_m_recv_len(&msgs[1]) ? I2C_SMBUS_BLOCK_MAX : msgs[1].len;
483 	unsigned long time_left;
484 
485 	axxia_i2c_set_addr(idev, &msgs[0]);
486 
487 	writel(msgs[0].len, idev->base + MST_TX_XFER);
488 	writel(rlen, idev->base + MST_RX_XFER);
489 
490 	idev->msg = &msgs[0];
491 	idev->msg_r = &msgs[1];
492 	idev->msg_xfrd = 0;
493 	idev->msg_xfrd_r = 0;
494 	idev->last = true;
495 	axxia_i2c_fill_tx_fifo(idev);
496 
497 	writel(CMD_SEQUENCE, idev->base + MST_COMMAND);
498 
499 	reinit_completion(&idev->msg_complete);
500 	i2c_int_enable(idev, int_mask);
501 
502 	time_left = wait_for_completion_timeout(&idev->msg_complete,
503 						I2C_XFER_TIMEOUT);
504 
505 	if (idev->msg_err == -ENXIO) {
506 		if (axxia_i2c_handle_seq_nak(idev))
507 			axxia_i2c_init(idev);
508 	} else if (readl(idev->base + MST_COMMAND) & CMD_BUSY) {
509 		dev_warn(idev->dev, "busy after xfer\n");
510 	}
511 
512 	if (time_left == 0) {
513 		idev->msg_err = -ETIMEDOUT;
514 		i2c_recover_bus(&idev->adapter);
515 		axxia_i2c_init(idev);
516 	}
517 
518 	if (unlikely(idev->msg_err) && idev->msg_err != -ENXIO)
519 		axxia_i2c_init(idev);
520 
521 	return idev->msg_err;
522 }
523 
524 static int axxia_i2c_xfer_msg(struct axxia_i2c_dev *idev, struct i2c_msg *msg,
525 			      bool last)
526 {
527 	u32 int_mask = MST_STATUS_ERR;
528 	u32 rx_xfer, tx_xfer;
529 	unsigned long time_left;
530 	unsigned int wt_value;
531 
532 	idev->msg = msg;
533 	idev->msg_r = msg;
534 	idev->msg_xfrd = 0;
535 	idev->msg_xfrd_r = 0;
536 	idev->last = last;
537 	reinit_completion(&idev->msg_complete);
538 
539 	axxia_i2c_set_addr(idev, msg);
540 
541 	if (i2c_m_rd(msg)) {
542 		/* I2C read transfer */
543 		rx_xfer = i2c_m_recv_len(msg) ? I2C_SMBUS_BLOCK_MAX : msg->len;
544 		tx_xfer = 0;
545 	} else {
546 		/* I2C write transfer */
547 		rx_xfer = 0;
548 		tx_xfer = msg->len;
549 	}
550 
551 	writel(rx_xfer, idev->base + MST_RX_XFER);
552 	writel(tx_xfer, idev->base + MST_TX_XFER);
553 
554 	if (i2c_m_rd(msg))
555 		int_mask |= MST_STATUS_RFL;
556 	else if (axxia_i2c_fill_tx_fifo(idev) != 0)
557 		int_mask |= MST_STATUS_TFL;
558 
559 	wt_value = WT_VALUE(readl(idev->base + WAIT_TIMER_CONTROL));
560 	/* Disable wait timer temporarly */
561 	writel(wt_value, idev->base + WAIT_TIMER_CONTROL);
562 	/* Check if timeout error happened */
563 	if (idev->msg_err)
564 		goto out;
565 
566 	if (!last) {
567 		writel(CMD_MANUAL, idev->base + MST_COMMAND);
568 		int_mask |= MST_STATUS_SNS;
569 	} else {
570 		writel(CMD_AUTO, idev->base + MST_COMMAND);
571 		int_mask |= MST_STATUS_SS;
572 	}
573 
574 	writel(WT_EN | wt_value, idev->base + WAIT_TIMER_CONTROL);
575 
576 	i2c_int_enable(idev, int_mask);
577 
578 	time_left = wait_for_completion_timeout(&idev->msg_complete,
579 					      I2C_XFER_TIMEOUT);
580 
581 	i2c_int_disable(idev, int_mask);
582 
583 	if (readl(idev->base + MST_COMMAND) & CMD_BUSY)
584 		dev_warn(idev->dev, "busy after xfer\n");
585 
586 	if (time_left == 0) {
587 		idev->msg_err = -ETIMEDOUT;
588 		i2c_recover_bus(&idev->adapter);
589 		axxia_i2c_init(idev);
590 	}
591 
592 out:
593 	if (unlikely(idev->msg_err) && idev->msg_err != -ENXIO &&
594 			idev->msg_err != -ETIMEDOUT)
595 		axxia_i2c_init(idev);
596 
597 	return idev->msg_err;
598 }
599 
600 /* This function checks if the msgs[] array contains messages compatible with
601  * Sequence mode of operation. This mode assumes there will be exactly one
602  * write of non-zero length followed by exactly one read of non-zero length,
603  * both targeted at the same client device.
604  */
605 static bool axxia_i2c_sequence_ok(struct i2c_msg msgs[], int num)
606 {
607 	return num == SEQ_LEN && !i2c_m_rd(&msgs[0]) && i2c_m_rd(&msgs[1]) &&
608 	       msgs[0].len > 0 && msgs[0].len <= FIFO_SIZE &&
609 	       msgs[1].len > 0 && msgs[0].addr == msgs[1].addr;
610 }
611 
612 static int
613 axxia_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
614 {
615 	struct axxia_i2c_dev *idev = i2c_get_adapdata(adap);
616 	int i;
617 	int ret = 0;
618 
619 	idev->msg_err = 0;
620 
621 	if (axxia_i2c_sequence_ok(msgs, num)) {
622 		ret = axxia_i2c_xfer_seq(idev, msgs);
623 		return ret ? : SEQ_LEN;
624 	}
625 
626 	i2c_int_enable(idev, MST_STATUS_TSS);
627 
628 	for (i = 0; ret == 0 && i < num; ++i)
629 		ret = axxia_i2c_xfer_msg(idev, &msgs[i], i == (num - 1));
630 
631 	return ret ? : i;
632 }
633 
634 static int axxia_i2c_get_scl(struct i2c_adapter *adap)
635 {
636 	struct axxia_i2c_dev *idev = i2c_get_adapdata(adap);
637 
638 	return !!(readl(idev->base + I2C_BUS_MONITOR) & BM_SCLS);
639 }
640 
641 static void axxia_i2c_set_scl(struct i2c_adapter *adap, int val)
642 {
643 	struct axxia_i2c_dev *idev = i2c_get_adapdata(adap);
644 	u32 tmp;
645 
646 	/* Preserve SDA Control */
647 	tmp = readl(idev->base + I2C_BUS_MONITOR) & BM_SDAC;
648 	if (!val)
649 		tmp |= BM_SCLC;
650 	writel(tmp, idev->base + I2C_BUS_MONITOR);
651 }
652 
653 static int axxia_i2c_get_sda(struct i2c_adapter *adap)
654 {
655 	struct axxia_i2c_dev *idev = i2c_get_adapdata(adap);
656 
657 	return !!(readl(idev->base + I2C_BUS_MONITOR) & BM_SDAS);
658 }
659 
660 static struct i2c_bus_recovery_info axxia_i2c_recovery_info = {
661 	.recover_bus = i2c_generic_scl_recovery,
662 	.get_scl = axxia_i2c_get_scl,
663 	.set_scl = axxia_i2c_set_scl,
664 	.get_sda = axxia_i2c_get_sda,
665 };
666 
667 static u32 axxia_i2c_func(struct i2c_adapter *adap)
668 {
669 	u32 caps = (I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR |
670 		    I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA);
671 	return caps;
672 }
673 
674 static int axxia_i2c_reg_slave(struct i2c_client *slave)
675 {
676 	struct axxia_i2c_dev *idev = i2c_get_adapdata(slave->adapter);
677 	u32 slv_int_mask = SLV_STATUS_RFH;
678 	u32 dec_ctl;
679 
680 	if (idev->slave)
681 		return -EBUSY;
682 
683 	idev->slave = slave;
684 
685 	/* Enable slave mode as well */
686 	writel(GLOBAL_MST_EN | GLOBAL_SLV_EN, idev->base + GLOBAL_CONTROL);
687 	writel(INT_MST | INT_SLV, idev->base + INTERRUPT_ENABLE);
688 
689 	/* Set slave address */
690 	dec_ctl = SLV_ADDR_DEC_SA1E;
691 	if (slave->flags & I2C_CLIENT_TEN)
692 		dec_ctl |= SLV_ADDR_DEC_SA1M;
693 
694 	writel(SLV_RX_ACSA1, idev->base + SLV_RX_CTL);
695 	writel(dec_ctl, idev->base + SLV_ADDR_DEC_CTL);
696 	writel(slave->addr, idev->base + SLV_ADDR_1);
697 
698 	/* Enable interrupts */
699 	slv_int_mask |= SLV_STATUS_SRS1 | SLV_STATUS_SRRS1 | SLV_STATUS_SRND1;
700 	slv_int_mask |= SLV_STATUS_SRC1;
701 	writel(slv_int_mask, idev->base + SLV_INT_ENABLE);
702 
703 	return 0;
704 }
705 
706 static int axxia_i2c_unreg_slave(struct i2c_client *slave)
707 {
708 	struct axxia_i2c_dev *idev = i2c_get_adapdata(slave->adapter);
709 
710 	/* Disable slave mode */
711 	writel(GLOBAL_MST_EN, idev->base + GLOBAL_CONTROL);
712 	writel(INT_MST, idev->base + INTERRUPT_ENABLE);
713 
714 	synchronize_irq(idev->irq);
715 
716 	idev->slave = NULL;
717 
718 	return 0;
719 }
720 
721 static const struct i2c_algorithm axxia_i2c_algo = {
722 	.master_xfer = axxia_i2c_xfer,
723 	.functionality = axxia_i2c_func,
724 	.reg_slave = axxia_i2c_reg_slave,
725 	.unreg_slave = axxia_i2c_unreg_slave,
726 };
727 
728 static const struct i2c_adapter_quirks axxia_i2c_quirks = {
729 	.max_read_len = 255,
730 	.max_write_len = 255,
731 };
732 
733 static int axxia_i2c_probe(struct platform_device *pdev)
734 {
735 	struct device_node *np = pdev->dev.of_node;
736 	struct axxia_i2c_dev *idev = NULL;
737 	void __iomem *base;
738 	int ret = 0;
739 
740 	idev = devm_kzalloc(&pdev->dev, sizeof(*idev), GFP_KERNEL);
741 	if (!idev)
742 		return -ENOMEM;
743 
744 	base = devm_platform_ioremap_resource(pdev, 0);
745 	if (IS_ERR(base))
746 		return PTR_ERR(base);
747 
748 	idev->irq = platform_get_irq(pdev, 0);
749 	if (idev->irq < 0)
750 		return idev->irq;
751 
752 	idev->i2c_clk = devm_clk_get(&pdev->dev, "i2c");
753 	if (IS_ERR(idev->i2c_clk)) {
754 		dev_err(&pdev->dev, "missing clock\n");
755 		return PTR_ERR(idev->i2c_clk);
756 	}
757 
758 	idev->base = base;
759 	idev->dev = &pdev->dev;
760 	init_completion(&idev->msg_complete);
761 
762 	of_property_read_u32(np, "clock-frequency", &idev->bus_clk_rate);
763 	if (idev->bus_clk_rate == 0)
764 		idev->bus_clk_rate = I2C_MAX_STANDARD_MODE_FREQ;	/* default clock rate */
765 
766 	ret = clk_prepare_enable(idev->i2c_clk);
767 	if (ret) {
768 		dev_err(&pdev->dev, "failed to enable clock\n");
769 		return ret;
770 	}
771 
772 	ret = axxia_i2c_init(idev);
773 	if (ret) {
774 		dev_err(&pdev->dev, "failed to initialize\n");
775 		goto error_disable_clk;
776 	}
777 
778 	ret = devm_request_irq(&pdev->dev, idev->irq, axxia_i2c_isr, 0,
779 			       pdev->name, idev);
780 	if (ret) {
781 		dev_err(&pdev->dev, "failed to claim IRQ%d\n", idev->irq);
782 		goto error_disable_clk;
783 	}
784 
785 	i2c_set_adapdata(&idev->adapter, idev);
786 	strlcpy(idev->adapter.name, pdev->name, sizeof(idev->adapter.name));
787 	idev->adapter.owner = THIS_MODULE;
788 	idev->adapter.algo = &axxia_i2c_algo;
789 	idev->adapter.bus_recovery_info = &axxia_i2c_recovery_info;
790 	idev->adapter.quirks = &axxia_i2c_quirks;
791 	idev->adapter.dev.parent = &pdev->dev;
792 	idev->adapter.dev.of_node = pdev->dev.of_node;
793 
794 	platform_set_drvdata(pdev, idev);
795 
796 	ret = i2c_add_adapter(&idev->adapter);
797 	if (ret)
798 		goto error_disable_clk;
799 
800 	return 0;
801 
802 error_disable_clk:
803 	clk_disable_unprepare(idev->i2c_clk);
804 	return ret;
805 }
806 
807 static int axxia_i2c_remove(struct platform_device *pdev)
808 {
809 	struct axxia_i2c_dev *idev = platform_get_drvdata(pdev);
810 
811 	clk_disable_unprepare(idev->i2c_clk);
812 	i2c_del_adapter(&idev->adapter);
813 
814 	return 0;
815 }
816 
817 /* Match table for of_platform binding */
818 static const struct of_device_id axxia_i2c_of_match[] = {
819 	{ .compatible = "lsi,api2c", },
820 	{},
821 };
822 
823 MODULE_DEVICE_TABLE(of, axxia_i2c_of_match);
824 
825 static struct platform_driver axxia_i2c_driver = {
826 	.probe = axxia_i2c_probe,
827 	.remove = axxia_i2c_remove,
828 	.driver = {
829 		.name = "axxia-i2c",
830 		.of_match_table = axxia_i2c_of_match,
831 	},
832 };
833 
834 module_platform_driver(axxia_i2c_driver);
835 
836 MODULE_DESCRIPTION("Axxia I2C Bus driver");
837 MODULE_AUTHOR("Anders Berg <anders.berg@lsi.com>");
838 MODULE_LICENSE("GPL v2");
839