1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * I2C bus driver for the Cadence I2C controller.
   4 *
   5 * Copyright (C) 2009 - 2014 Xilinx, Inc.
   6 */
   7
   8#include <linux/clk.h>
   9#include <linux/delay.h>
  10#include <linux/i2c.h>
  11#include <linux/interrupt.h>
  12#include <linux/io.h>
  13#include <linux/iopoll.h>
  14#include <linux/module.h>
  15#include <linux/platform_device.h>
  16#include <linux/of.h>
  17#include <linux/pm_runtime.h>
  18#include <linux/pinctrl/consumer.h>
  19#include <linux/reset.h>
  20
  21/* Register offsets for the I2C device. */
  22#define CDNS_I2C_CR_OFFSET		0x00 /* Control Register, RW */
  23#define CDNS_I2C_SR_OFFSET		0x04 /* Status Register, RO */
  24#define CDNS_I2C_ADDR_OFFSET		0x08 /* I2C Address Register, RW */
  25#define CDNS_I2C_DATA_OFFSET		0x0C /* I2C Data Register, RW */
  26#define CDNS_I2C_ISR_OFFSET		0x10 /* IRQ Status Register, RW */
  27#define CDNS_I2C_XFER_SIZE_OFFSET	0x14 /* Transfer Size Register, RW */
  28#define CDNS_I2C_TIME_OUT_OFFSET	0x1C /* Time Out Register, RW */
  29#define CDNS_I2C_IMR_OFFSET		0x20 /* IRQ Mask Register, RO */
  30#define CDNS_I2C_IER_OFFSET		0x24 /* IRQ Enable Register, WO */
  31#define CDNS_I2C_IDR_OFFSET		0x28 /* IRQ Disable Register, WO */
  32
  33/* Control Register Bit mask definitions */
  34#define CDNS_I2C_CR_HOLD		BIT(4) /* Hold Bus bit */
  35#define CDNS_I2C_CR_ACK_EN		BIT(3)
  36#define CDNS_I2C_CR_NEA			BIT(2)
  37#define CDNS_I2C_CR_MS			BIT(1)
  38/* Read or Write Master transfer 0 = Transmitter, 1 = Receiver */
  39#define CDNS_I2C_CR_RW			BIT(0)
  40/* 1 = Auto init FIFO to zeroes */
  41#define CDNS_I2C_CR_CLR_FIFO		BIT(6)
  42#define CDNS_I2C_CR_DIVA_SHIFT		14
  43#define CDNS_I2C_CR_DIVA_MASK		(3 << CDNS_I2C_CR_DIVA_SHIFT)
  44#define CDNS_I2C_CR_DIVB_SHIFT		8
  45#define CDNS_I2C_CR_DIVB_MASK		(0x3f << CDNS_I2C_CR_DIVB_SHIFT)
  46
  47#define CDNS_I2C_CR_MASTER_EN_MASK	(CDNS_I2C_CR_NEA | \
  48					 CDNS_I2C_CR_ACK_EN | \
  49					 CDNS_I2C_CR_MS)
  50
  51#define CDNS_I2C_CR_SLAVE_EN_MASK	~CDNS_I2C_CR_MASTER_EN_MASK
  52
  53/* Status Register Bit mask definitions */
  54#define CDNS_I2C_SR_BA		BIT(8)
  55#define CDNS_I2C_SR_TXDV	BIT(6)
  56#define CDNS_I2C_SR_RXDV	BIT(5)
  57#define CDNS_I2C_SR_RXRW	BIT(3)
  58
  59/*
  60 * I2C Address Register Bit mask definitions
  61 * Normal addressing mode uses [6:0] bits. Extended addressing mode uses [9:0]
  62 * bits. A write access to this register always initiates a transfer if the I2C
  63 * is in master mode.
  64 */
  65#define CDNS_I2C_ADDR_MASK	0x000003FF /* I2C Address Mask */
  66
  67/*
  68 * I2C Interrupt Registers Bit mask definitions
  69 * All the four interrupt registers (Status/Mask/Enable/Disable) have the same
  70 * bit definitions.
  71 */
  72#define CDNS_I2C_IXR_ARB_LOST		BIT(9)
  73#define CDNS_I2C_IXR_RX_UNF		BIT(7)
  74#define CDNS_I2C_IXR_TX_OVF		BIT(6)
  75#define CDNS_I2C_IXR_RX_OVF		BIT(5)
  76#define CDNS_I2C_IXR_SLV_RDY		BIT(4)
  77#define CDNS_I2C_IXR_TO			BIT(3)
  78#define CDNS_I2C_IXR_NACK		BIT(2)
  79#define CDNS_I2C_IXR_DATA		BIT(1)
  80#define CDNS_I2C_IXR_COMP		BIT(0)
  81
  82#define CDNS_I2C_IXR_ALL_INTR_MASK	(CDNS_I2C_IXR_ARB_LOST | \
  83					 CDNS_I2C_IXR_RX_UNF | \
  84					 CDNS_I2C_IXR_TX_OVF | \
  85					 CDNS_I2C_IXR_RX_OVF | \
  86					 CDNS_I2C_IXR_SLV_RDY | \
  87					 CDNS_I2C_IXR_TO | \
  88					 CDNS_I2C_IXR_NACK | \
  89					 CDNS_I2C_IXR_DATA | \
  90					 CDNS_I2C_IXR_COMP)
  91
  92#define CDNS_I2C_IXR_ERR_INTR_MASK	(CDNS_I2C_IXR_ARB_LOST | \
  93					 CDNS_I2C_IXR_RX_UNF | \
  94					 CDNS_I2C_IXR_TX_OVF | \
  95					 CDNS_I2C_IXR_RX_OVF | \
  96					 CDNS_I2C_IXR_NACK)
  97
  98#define CDNS_I2C_ENABLED_INTR_MASK	(CDNS_I2C_IXR_ARB_LOST | \
  99					 CDNS_I2C_IXR_RX_UNF | \
 100					 CDNS_I2C_IXR_TX_OVF | \
 101					 CDNS_I2C_IXR_RX_OVF | \
 102					 CDNS_I2C_IXR_NACK | \
 103					 CDNS_I2C_IXR_DATA | \
 104					 CDNS_I2C_IXR_COMP)
 105
 106#define CDNS_I2C_IXR_SLAVE_INTR_MASK	(CDNS_I2C_IXR_RX_UNF | \
 107					 CDNS_I2C_IXR_TX_OVF | \
 108					 CDNS_I2C_IXR_RX_OVF | \
 109					 CDNS_I2C_IXR_TO | \
 110					 CDNS_I2C_IXR_NACK | \
 111					 CDNS_I2C_IXR_DATA | \
 112					 CDNS_I2C_IXR_COMP)
 113
 114#define CDNS_I2C_TIMEOUT		msecs_to_jiffies(1000)
 115/* timeout for pm runtime autosuspend */
 116#define CNDS_I2C_PM_TIMEOUT		1000	/* ms */
 117
 118#define CDNS_I2C_FIFO_DEPTH_DEFAULT	16
 119#define CDNS_I2C_MAX_TRANSFER_SIZE	255
 120/* Transfer size in multiples of data interrupt depth */
 121#define CDNS_I2C_TRANSFER_SIZE(max)	((max) - 3)
 122
 123#define DRIVER_NAME		"cdns-i2c"
 124
 125#define CDNS_I2C_DIVA_MAX	4
 126#define CDNS_I2C_DIVB_MAX	64
 127
 128#define CDNS_I2C_TIMEOUT_MAX	0xFF
 129
 130#define CDNS_I2C_BROKEN_HOLD_BIT	BIT(0)
 131#define CDNS_I2C_POLL_US	100000
 132#define CDNS_I2C_POLL_US_ATOMIC	10
 133#define CDNS_I2C_TIMEOUT_US	500000
 134
 135#define cdns_i2c_readreg(offset)       readl_relaxed(id->membase + offset)
 136#define cdns_i2c_writereg(val, offset) writel_relaxed(val, id->membase + offset)
 137
 138#if IS_ENABLED(CONFIG_I2C_SLAVE)
 139/**
 140 * enum cdns_i2c_mode - I2C Controller current operating mode
 141 *
 142 * @CDNS_I2C_MODE_SLAVE:       I2C controller operating in slave mode
 143 * @CDNS_I2C_MODE_MASTER:      I2C Controller operating in master mode
 144 */
 145enum cdns_i2c_mode {
 146	CDNS_I2C_MODE_SLAVE,
 147	CDNS_I2C_MODE_MASTER,
 148};
 149
 150/**
 151 * enum cdns_i2c_slave_state - Slave state when I2C is operating in slave mode
 152 *
 153 * @CDNS_I2C_SLAVE_STATE_IDLE: I2C slave idle
 154 * @CDNS_I2C_SLAVE_STATE_SEND: I2C slave sending data to master
 155 * @CDNS_I2C_SLAVE_STATE_RECV: I2C slave receiving data from master
 156 */
 157enum cdns_i2c_slave_state {
 158	CDNS_I2C_SLAVE_STATE_IDLE,
 159	CDNS_I2C_SLAVE_STATE_SEND,
 160	CDNS_I2C_SLAVE_STATE_RECV,
 161};
 162#endif
 163
 164/**
 165 * struct cdns_i2c - I2C device private data structure
 166 *
 167 * @dev:		Pointer to device structure
 168 * @membase:		Base address of the I2C device
 169 * @adap:		I2C adapter instance
 170 * @p_msg:		Message pointer
 171 * @err_status:		Error status in Interrupt Status Register
 172 * @xfer_done:		Transfer complete status
 173 * @p_send_buf:		Pointer to transmit buffer
 174 * @p_recv_buf:		Pointer to receive buffer
 175 * @send_count:		Number of bytes still expected to send
 176 * @recv_count:		Number of bytes still expected to receive
 177 * @curr_recv_count:	Number of bytes to be received in current transfer
 178 * @input_clk:		Input clock to I2C controller
 179 * @i2c_clk:		Maximum I2C clock speed
 180 * @bus_hold_flag:	Flag used in repeated start for clearing HOLD bit
 181 * @clk:		Pointer to struct clk
 182 * @clk_rate_change_nb:	Notifier block for clock rate changes
 183 * @reset:		Reset control for the device
 184 * @quirks:		flag for broken hold bit usage in r1p10
 185 * @ctrl_reg:		Cached value of the control register.
 186 * @rinfo:		I2C GPIO recovery information
 187 * @ctrl_reg_diva_divb: value of fields DIV_A and DIV_B from CR register
 188 * @slave:		Registered slave instance.
 189 * @dev_mode:		I2C operating role(master/slave).
 190 * @slave_state:	I2C Slave state(idle/read/write).
 191 * @fifo_depth:		The depth of the transfer FIFO
 192 * @transfer_size:	The maximum number of bytes in one transfer
 193 * @atomic:		Mode of transfer
 194 * @err_status_atomic:	Error status in atomic mode
 195 */
 196struct cdns_i2c {
 197	struct device		*dev;
 198	void __iomem *membase;
 199	struct i2c_adapter adap;
 200	struct i2c_msg *p_msg;
 201	int err_status;
 202	struct completion xfer_done;
 203	unsigned char *p_send_buf;
 204	unsigned char *p_recv_buf;
 205	unsigned int send_count;
 206	unsigned int recv_count;
 207	unsigned int curr_recv_count;
 208	unsigned long input_clk;
 209	unsigned int i2c_clk;
 210	unsigned int bus_hold_flag;
 211	struct clk *clk;
 212	struct notifier_block clk_rate_change_nb;
 213	struct reset_control *reset;
 214	u32 quirks;
 215	u32 ctrl_reg;
 216	struct i2c_bus_recovery_info rinfo;
 217#if IS_ENABLED(CONFIG_I2C_SLAVE)
 218	u16 ctrl_reg_diva_divb;
 219	struct i2c_client *slave;
 220	enum cdns_i2c_mode dev_mode;
 221	enum cdns_i2c_slave_state slave_state;
 222#endif
 223	u32 fifo_depth;
 224	unsigned int transfer_size;
 225	bool atomic;
 226	int err_status_atomic;
 227};
 228
 229struct cdns_platform_data {
 230	u32 quirks;
 231};
 232
 233#define to_cdns_i2c(_nb)	container_of(_nb, struct cdns_i2c, \
 234					     clk_rate_change_nb)
 235
 236/**
 237 * cdns_i2c_init -  Controller initialisation
 238 * @id:		Device private data structure
 239 *
 240 * Initialise the i2c controller.
 241 *
 242 */
 243static void cdns_i2c_init(struct cdns_i2c *id)
 244{
 245	cdns_i2c_writereg(id->ctrl_reg, CDNS_I2C_CR_OFFSET);
 246	/*
 247	 * Cadence I2C controller has a bug wherein it generates
 248	 * invalid read transaction after HW timeout in master receiver mode.
 249	 * HW timeout is not used by this driver and the interrupt is disabled.
 250	 * But the feature itself cannot be disabled. Hence maximum value
 251	 * is written to this register to reduce the chances of error.
 252	 */
 253	cdns_i2c_writereg(CDNS_I2C_TIMEOUT_MAX, CDNS_I2C_TIME_OUT_OFFSET);
 254}
 255
 256/**
 257 * cdns_i2c_runtime_suspend -  Runtime suspend method for the driver
 258 * @dev:	Address of the platform_device structure
 259 *
 260 * Put the driver into low power mode.
 261 *
 262 * Return: 0 always
 263 */
 264static int cdns_i2c_runtime_suspend(struct device *dev)
 265{
 266	struct cdns_i2c *xi2c = dev_get_drvdata(dev);
 267
 268	clk_disable(xi2c->clk);
 269
 270	return 0;
 271}
 272
 273/**
 274 * cdns_i2c_runtime_resume - Runtime resume
 275 * @dev:	Address of the platform_device structure
 276 *
 277 * Runtime resume callback.
 278 *
 279 * Return: 0 on success and error value on error
 280 */
 281static int cdns_i2c_runtime_resume(struct device *dev)
 282{
 283	struct cdns_i2c *xi2c = dev_get_drvdata(dev);
 284	int ret;
 285
 286	ret = clk_enable(xi2c->clk);
 287	if (ret) {
 288		dev_err(dev, "Cannot enable clock.\n");
 289		return ret;
 290	}
 291	cdns_i2c_init(xi2c);
 292
 293	return 0;
 294}
 295
 296/**
 297 * cdns_i2c_clear_bus_hold - Clear bus hold bit
 298 * @id:	Pointer to driver data struct
 299 *
 300 * Helper to clear the controller's bus hold bit.
 301 */
 302static void cdns_i2c_clear_bus_hold(struct cdns_i2c *id)
 303{
 304	u32 reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
 305	if (reg & CDNS_I2C_CR_HOLD)
 306		cdns_i2c_writereg(reg & ~CDNS_I2C_CR_HOLD, CDNS_I2C_CR_OFFSET);
 307}
 308
 309static inline bool cdns_is_holdquirk(struct cdns_i2c *id, bool hold_wrkaround)
 310{
 311	return (hold_wrkaround &&
 312		(id->curr_recv_count == id->fifo_depth + 1));
 313}
 314
 315#if IS_ENABLED(CONFIG_I2C_SLAVE)
 316static void cdns_i2c_set_mode(enum cdns_i2c_mode mode, struct cdns_i2c *id)
 317{
 318	/* Disable all interrupts */
 319	cdns_i2c_writereg(CDNS_I2C_IXR_ALL_INTR_MASK, CDNS_I2C_IDR_OFFSET);
 320
 321	/* Clear FIFO and transfer size */
 322	cdns_i2c_writereg(CDNS_I2C_CR_CLR_FIFO, CDNS_I2C_CR_OFFSET);
 323
 324	/* Update device mode and state */
 325	id->dev_mode = mode;
 326	id->slave_state = CDNS_I2C_SLAVE_STATE_IDLE;
 327
 328	switch (mode) {
 329	case CDNS_I2C_MODE_MASTER:
 330		/* Enable i2c master */
 331		cdns_i2c_writereg(id->ctrl_reg_diva_divb |
 332				  CDNS_I2C_CR_MASTER_EN_MASK,
 333				  CDNS_I2C_CR_OFFSET);
 334		/*
 335		 * This delay is needed to give the IP some time to switch to
 336		 * the master mode. With lower values(like 110 us) i2cdetect
 337		 * will not detect any slave and without this delay, the IP will
 338		 * trigger a timeout interrupt.
 339		 */
 340		usleep_range(115, 125);
 341		break;
 342	case CDNS_I2C_MODE_SLAVE:
 343		/* Enable i2c slave */
 344		cdns_i2c_writereg(id->ctrl_reg_diva_divb &
 345				  CDNS_I2C_CR_SLAVE_EN_MASK,
 346				  CDNS_I2C_CR_OFFSET);
 347
 348		/* Setting slave address */
 349		cdns_i2c_writereg(id->slave->addr & CDNS_I2C_ADDR_MASK,
 350				  CDNS_I2C_ADDR_OFFSET);
 351
 352		/* Enable slave send/receive interrupts */
 353		cdns_i2c_writereg(CDNS_I2C_IXR_SLAVE_INTR_MASK,
 354				  CDNS_I2C_IER_OFFSET);
 355		break;
 356	}
 357}
 358
 359static void cdns_i2c_slave_rcv_data(struct cdns_i2c *id)
 360{
 361	u8 bytes;
 362	unsigned char data;
 363
 364	/* Prepare backend for data reception */
 365	if (id->slave_state == CDNS_I2C_SLAVE_STATE_IDLE) {
 366		id->slave_state = CDNS_I2C_SLAVE_STATE_RECV;
 367		i2c_slave_event(id->slave, I2C_SLAVE_WRITE_REQUESTED, NULL);
 368	}
 369
 370	/* Fetch number of bytes to receive */
 371	bytes = cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET);
 372
 373	/* Read data and send to backend */
 374	while (bytes--) {
 375		data = cdns_i2c_readreg(CDNS_I2C_DATA_OFFSET);
 376		i2c_slave_event(id->slave, I2C_SLAVE_WRITE_RECEIVED, &data);
 377	}
 378}
 379
 380static void cdns_i2c_slave_send_data(struct cdns_i2c *id)
 381{
 382	u8 data;
 383
 384	/* Prepare backend for data transmission */
 385	if (id->slave_state == CDNS_I2C_SLAVE_STATE_IDLE) {
 386		id->slave_state = CDNS_I2C_SLAVE_STATE_SEND;
 387		i2c_slave_event(id->slave, I2C_SLAVE_READ_REQUESTED, &data);
 388	} else {
 389		i2c_slave_event(id->slave, I2C_SLAVE_READ_PROCESSED, &data);
 390	}
 391
 392	/* Send data over bus */
 393	cdns_i2c_writereg(data, CDNS_I2C_DATA_OFFSET);
 394}
 395
 396/**
 397 * cdns_i2c_slave_isr - Interrupt handler for the I2C device in slave role
 398 * @ptr:       Pointer to I2C device private data
 399 *
 400 * This function handles the data interrupt and transfer complete interrupt of
 401 * the I2C device in slave role.
 402 *
 403 * Return: IRQ_HANDLED always
 404 */
 405static irqreturn_t cdns_i2c_slave_isr(void *ptr)
 406{
 407	struct cdns_i2c *id = ptr;
 408	unsigned int isr_status, i2c_status;
 409
 410	/* Fetch the interrupt status */
 411	isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET);
 412	cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET);
 413
 414	/* Ignore masked interrupts */
 415	isr_status &= ~cdns_i2c_readreg(CDNS_I2C_IMR_OFFSET);
 416
 417	/* Fetch transfer mode (send/receive) */
 418	i2c_status = cdns_i2c_readreg(CDNS_I2C_SR_OFFSET);
 419
 420	/* Handle data send/receive */
 421	if (i2c_status & CDNS_I2C_SR_RXRW) {
 422		/* Send data to master */
 423		if (isr_status & CDNS_I2C_IXR_DATA)
 424			cdns_i2c_slave_send_data(id);
 425
 426		if (isr_status & CDNS_I2C_IXR_COMP) {
 427			id->slave_state = CDNS_I2C_SLAVE_STATE_IDLE;
 428			i2c_slave_event(id->slave, I2C_SLAVE_STOP, NULL);
 429		}
 430	} else {
 431		/* Receive data from master */
 432		if (isr_status & CDNS_I2C_IXR_DATA)
 433			cdns_i2c_slave_rcv_data(id);
 434
 435		if (isr_status & CDNS_I2C_IXR_COMP) {
 436			cdns_i2c_slave_rcv_data(id);
 437			id->slave_state = CDNS_I2C_SLAVE_STATE_IDLE;
 438			i2c_slave_event(id->slave, I2C_SLAVE_STOP, NULL);
 439		}
 440	}
 441
 442	/* Master indicated xfer stop or fifo underflow/overflow */
 443	if (isr_status & (CDNS_I2C_IXR_NACK | CDNS_I2C_IXR_RX_OVF |
 444			  CDNS_I2C_IXR_RX_UNF | CDNS_I2C_IXR_TX_OVF)) {
 445		id->slave_state = CDNS_I2C_SLAVE_STATE_IDLE;
 446		i2c_slave_event(id->slave, I2C_SLAVE_STOP, NULL);
 447		cdns_i2c_writereg(CDNS_I2C_CR_CLR_FIFO, CDNS_I2C_CR_OFFSET);
 448	}
 449
 450	return IRQ_HANDLED;
 451}
 452#endif
 453
 454/**
 455 * cdns_i2c_master_isr - Interrupt handler for the I2C device in master role
 456 * @ptr:       Pointer to I2C device private data
 457 *
 458 * This function handles the data interrupt, transfer complete interrupt and
 459 * the error interrupts of the I2C device in master role.
 460 *
 461 * Return: IRQ_HANDLED always
 462 */
 463static irqreturn_t cdns_i2c_master_isr(void *ptr)
 464{
 465	unsigned int isr_status, avail_bytes;
 466	unsigned int bytes_to_send;
 467	bool updatetx;
 468	struct cdns_i2c *id = ptr;
 469	/* Signal completion only after everything is updated */
 470	int done_flag = 0;
 471	irqreturn_t status = IRQ_NONE;
 472
 473	isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET);
 474	cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET);
 475	id->err_status = 0;
 476
 477	/* Handling nack and arbitration lost interrupt */
 478	if (isr_status & (CDNS_I2C_IXR_NACK | CDNS_I2C_IXR_ARB_LOST)) {
 479		done_flag = 1;
 480		status = IRQ_HANDLED;
 481	}
 482
 483	/*
 484	 * Check if transfer size register needs to be updated again for a
 485	 * large data receive operation.
 486	 */
 487	updatetx = id->recv_count > id->curr_recv_count;
 488
 489	/* When receiving, handle data interrupt and completion interrupt */
 490	if (id->p_recv_buf &&
 491	    ((isr_status & CDNS_I2C_IXR_COMP) ||
 492	     (isr_status & CDNS_I2C_IXR_DATA))) {
 493		/* Read data if receive data valid is set */
 494		while (cdns_i2c_readreg(CDNS_I2C_SR_OFFSET) &
 495		       CDNS_I2C_SR_RXDV) {
 496			if (id->recv_count > 0) {
 497				*(id->p_recv_buf)++ =
 498					cdns_i2c_readreg(CDNS_I2C_DATA_OFFSET);
 499				id->recv_count--;
 500				id->curr_recv_count--;
 501
 502				/*
 503				 * Clear hold bit that was set for FIFO control
 504				 * if RX data left is less than or equal to
 505				 * FIFO DEPTH unless repeated start is selected
 506				 */
 507				if (id->recv_count <= id->fifo_depth &&
 508				    !id->bus_hold_flag)
 509					cdns_i2c_clear_bus_hold(id);
 510
 511			} else {
 512				dev_err(id->adap.dev.parent,
 513					"xfer_size reg rollover. xfer aborted!\n");
 514				id->err_status |= CDNS_I2C_IXR_TO;
 515				break;
 516			}
 517
 518			if (cdns_is_holdquirk(id, updatetx))
 519				break;
 520		}
 521
 522		/*
 523		 * The controller sends NACK to the slave when transfer size
 524		 * register reaches zero without considering the HOLD bit.
 525		 * This workaround is implemented for large data transfers to
 526		 * maintain transfer size non-zero while performing a large
 527		 * receive operation.
 528		 */
 529		if (cdns_is_holdquirk(id, updatetx)) {
 530			/* wait while fifo is full */
 531			while (cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET) !=
 532			       (id->curr_recv_count - id->fifo_depth))
 533				;
 534
 535			/*
 536			 * Check number of bytes to be received against maximum
 537			 * transfer size and update register accordingly.
 538			 */
 539			if (((int)(id->recv_count) - id->fifo_depth) >
 540			    id->transfer_size) {
 541				cdns_i2c_writereg(id->transfer_size,
 542						  CDNS_I2C_XFER_SIZE_OFFSET);
 543				id->curr_recv_count = id->transfer_size +
 544						      id->fifo_depth;
 545			} else {
 546				cdns_i2c_writereg(id->recv_count -
 547						  id->fifo_depth,
 548						  CDNS_I2C_XFER_SIZE_OFFSET);
 549				id->curr_recv_count = id->recv_count;
 550			}
 551		}
 552
 553		/* Clear hold (if not repeated start) and signal completion */
 554		if ((isr_status & CDNS_I2C_IXR_COMP) && !id->recv_count) {
 555			if (!id->bus_hold_flag)
 556				cdns_i2c_clear_bus_hold(id);
 557			done_flag = 1;
 558		}
 559
 560		status = IRQ_HANDLED;
 561	}
 562
 563	/* When sending, handle transfer complete interrupt */
 564	if ((isr_status & CDNS_I2C_IXR_COMP) && !id->p_recv_buf) {
 565		/*
 566		 * If there is more data to be sent, calculate the
 567		 * space available in FIFO and fill with that many bytes.
 568		 */
 569		if (id->send_count) {
 570			avail_bytes = id->fifo_depth -
 571			    cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET);
 572			if (id->send_count > avail_bytes)
 573				bytes_to_send = avail_bytes;
 574			else
 575				bytes_to_send = id->send_count;
 576
 577			while (bytes_to_send--) {
 578				cdns_i2c_writereg(
 579					(*(id->p_send_buf)++),
 580					 CDNS_I2C_DATA_OFFSET);
 581				id->send_count--;
 582			}
 583		} else {
 584			/*
 585			 * Signal the completion of transaction and
 586			 * clear the hold bus bit if there are no
 587			 * further messages to be processed.
 588			 */
 589			done_flag = 1;
 590		}
 591		if (!id->send_count && !id->bus_hold_flag)
 592			cdns_i2c_clear_bus_hold(id);
 593
 594		status = IRQ_HANDLED;
 595	}
 596
 597	/* Update the status for errors */
 598	id->err_status |= isr_status & CDNS_I2C_IXR_ERR_INTR_MASK;
 599	if (id->err_status)
 600		status = IRQ_HANDLED;
 601
 602	if (done_flag)
 603		complete(&id->xfer_done);
 604
 605	return status;
 606}
 607
 608/**
 609 * cdns_i2c_isr - Interrupt handler for the I2C device
 610 * @irq:	irq number for the I2C device
 611 * @ptr:	void pointer to cdns_i2c structure
 612 *
 613 * This function passes the control to slave/master based on current role of
 614 * i2c controller.
 615 *
 616 * Return: IRQ_HANDLED always
 617 */
 618static irqreturn_t cdns_i2c_isr(int irq, void *ptr)
 619{
 620#if IS_ENABLED(CONFIG_I2C_SLAVE)
 621	struct cdns_i2c *id = ptr;
 622
 623	if (id->dev_mode == CDNS_I2C_MODE_SLAVE)
 624		return cdns_i2c_slave_isr(ptr);
 625#endif
 626	return cdns_i2c_master_isr(ptr);
 627}
 628
 629static bool cdns_i2c_error_check(struct cdns_i2c *id)
 630{
 631	unsigned int isr_status;
 632
 633	id->err_status = 0;
 634
 635	isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET);
 636	cdns_i2c_writereg(isr_status & CDNS_I2C_IXR_ERR_INTR_MASK, CDNS_I2C_ISR_OFFSET);
 637
 638	id->err_status = isr_status & CDNS_I2C_IXR_ERR_INTR_MASK;
 639
 640	return !!id->err_status;
 641}
 642
 643static void cdns_i2c_mrecv_atomic(struct cdns_i2c *id)
 644{
 645	while (id->recv_count > 0) {
 646		bool updatetx;
 647
 648		/*
 649		 * Check if transfer size register needs to be updated again for a
 650		 * large data receive operation.
 651		 */
 652		updatetx = id->recv_count > id->curr_recv_count;
 653
 654		while (id->curr_recv_count > 0) {
 655			if (cdns_i2c_readreg(CDNS_I2C_SR_OFFSET) & CDNS_I2C_SR_RXDV) {
 656				*id->p_recv_buf = cdns_i2c_readreg(CDNS_I2C_DATA_OFFSET);
 657				id->p_recv_buf++;
 658				id->recv_count--;
 659				id->curr_recv_count--;
 660
 661				/*
 662				 * Clear the hold bit that was set for FIFO control,
 663				 * if the remaining RX data is less than or equal to
 664				 * the FIFO depth, unless a repeated start is selected.
 665				 */
 666				if (id->recv_count <= id->fifo_depth && !id->bus_hold_flag)
 667					cdns_i2c_clear_bus_hold(id);
 668			}
 669			if (cdns_i2c_error_check(id))
 670				return;
 671			if (cdns_is_holdquirk(id, updatetx))
 672				break;
 673		}
 674
 675		/*
 676		 * The controller sends NACK to the slave/target when transfer size
 677		 * register reaches zero without considering the HOLD bit.
 678		 * This workaround is implemented for large data transfers to
 679		 * maintain transfer size non-zero while performing a large
 680		 * receive operation.
 681		 */
 682		if (cdns_is_holdquirk(id, updatetx)) {
 683			/* wait while fifo is full */
 684			while (cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET) !=
 685			       (id->curr_recv_count - id->fifo_depth))
 686				;
 687
 688			/*
 689			 * Check number of bytes to be received against maximum
 690			 * transfer size and update register accordingly.
 691			 */
 692			if ((id->recv_count - id->fifo_depth) >
 693			    id->transfer_size) {
 694				cdns_i2c_writereg(id->transfer_size,
 695						  CDNS_I2C_XFER_SIZE_OFFSET);
 696				id->curr_recv_count = id->transfer_size +
 697						      id->fifo_depth;
 698			} else {
 699				cdns_i2c_writereg(id->recv_count -
 700						  id->fifo_depth,
 701						  CDNS_I2C_XFER_SIZE_OFFSET);
 702				id->curr_recv_count = id->recv_count;
 703			}
 704		}
 705	}
 706
 707	/* Clear hold (if not repeated start) */
 708	if (!id->recv_count && !id->bus_hold_flag)
 709		cdns_i2c_clear_bus_hold(id);
 710}
 711
 712/**
 713 * cdns_i2c_mrecv - Prepare and start a master receive operation
 714 * @id:		pointer to the i2c device structure
 715 */
 716static void cdns_i2c_mrecv(struct cdns_i2c *id)
 717{
 718	unsigned int ctrl_reg;
 719	unsigned int isr_status;
 720	unsigned long flags;
 721	bool hold_clear = false;
 722	bool irq_save = false;
 723
 724	u32 addr;
 725
 726	id->p_recv_buf = id->p_msg->buf;
 727	id->recv_count = id->p_msg->len;
 728
 729	/* Put the controller in master receive mode and clear the FIFO */
 730	ctrl_reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
 731	ctrl_reg |= CDNS_I2C_CR_RW | CDNS_I2C_CR_CLR_FIFO;
 732
 733	/*
 734	 * Receive up to I2C_SMBUS_BLOCK_MAX data bytes, plus one message length
 735	 * byte, plus one checksum byte if PEC is enabled. p_msg->len will be 2 if
 736	 * PEC is enabled, otherwise 1.
 737	 */
 738	if (id->p_msg->flags & I2C_M_RECV_LEN)
 739		id->recv_count = I2C_SMBUS_BLOCK_MAX + id->p_msg->len;
 740
 741	id->curr_recv_count = id->recv_count;
 742
 743	/*
 744	 * Check for the message size against FIFO depth and set the
 745	 * 'hold bus' bit if it is greater than FIFO depth.
 746	 */
 747	if (id->recv_count > id->fifo_depth)
 748		ctrl_reg |= CDNS_I2C_CR_HOLD;
 749
 750	cdns_i2c_writereg(ctrl_reg, CDNS_I2C_CR_OFFSET);
 751
 752	/* Clear the interrupts in interrupt status register */
 753	isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET);
 754	cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET);
 755
 756	/*
 757	 * The no. of bytes to receive is checked against the limit of
 758	 * max transfer size. Set transfer size register with no of bytes
 759	 * receive if it is less than transfer size and transfer size if
 760	 * it is more. Enable the interrupts.
 761	 */
 762	if (id->recv_count > id->transfer_size) {
 763		cdns_i2c_writereg(id->transfer_size,
 764				  CDNS_I2C_XFER_SIZE_OFFSET);
 765		id->curr_recv_count = id->transfer_size;
 766	} else {
 767		cdns_i2c_writereg(id->recv_count, CDNS_I2C_XFER_SIZE_OFFSET);
 768	}
 769
 770	/* Determine hold_clear based on number of bytes to receive and hold flag */
 771	if (!id->bus_hold_flag && id->recv_count <= id->fifo_depth) {
 772		if (ctrl_reg & CDNS_I2C_CR_HOLD) {
 773			hold_clear = true;
 774			if (id->quirks & CDNS_I2C_BROKEN_HOLD_BIT)
 775				irq_save = true;
 776		}
 777	}
 778
 779	addr = id->p_msg->addr;
 780	addr &= CDNS_I2C_ADDR_MASK;
 781
 782	if (hold_clear) {
 783		ctrl_reg &= ~CDNS_I2C_CR_HOLD;
 784		ctrl_reg &= ~CDNS_I2C_CR_CLR_FIFO;
 785		/*
 786		 * In case of Xilinx Zynq SOC, clear the HOLD bit before transfer size
 787		 * register reaches '0'. This is an IP bug which causes transfer size
 788		 * register overflow to 0xFF. To satisfy this timing requirement,
 789		 * disable the interrupts on current processor core between register
 790		 * writes to slave address register and control register.
 791		 */
 792		if (irq_save)
 793			local_irq_save(flags);
 794
 795		cdns_i2c_writereg(addr, CDNS_I2C_ADDR_OFFSET);
 796		cdns_i2c_writereg(ctrl_reg, CDNS_I2C_CR_OFFSET);
 797		/* Read it back to avoid bufferring and make sure write happens */
 798		cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
 799
 800		if (irq_save)
 801			local_irq_restore(flags);
 802	} else {
 803		cdns_i2c_writereg(addr, CDNS_I2C_ADDR_OFFSET);
 804	}
 805
 806	if (!id->atomic)
 807		cdns_i2c_writereg(CDNS_I2C_ENABLED_INTR_MASK, CDNS_I2C_IER_OFFSET);
 808	else
 809		cdns_i2c_mrecv_atomic(id);
 810}
 811
 812static void cdns_i2c_msend_rem_atomic(struct cdns_i2c *id)
 813{
 814	while (id->send_count) {
 815		unsigned int avail_bytes;
 816		unsigned int bytes_to_send;
 817
 818		avail_bytes = id->fifo_depth - cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET);
 819		if (id->send_count > avail_bytes)
 820			bytes_to_send = avail_bytes;
 821		else
 822			bytes_to_send = id->send_count;
 823
 824		while (bytes_to_send--) {
 825			cdns_i2c_writereg((*id->p_send_buf++), CDNS_I2C_DATA_OFFSET);
 826			id->send_count--;
 827		}
 828		if (cdns_i2c_error_check(id))
 829			return;
 830	}
 831
 832	if (!id->send_count && !id->bus_hold_flag)
 833		cdns_i2c_clear_bus_hold(id);
 834}
 835
 836/**
 837 * cdns_i2c_msend - Prepare and start a master send operation
 838 * @id:		pointer to the i2c device
 839 */
 840static void cdns_i2c_msend(struct cdns_i2c *id)
 841{
 842	unsigned int avail_bytes;
 843	unsigned int bytes_to_send;
 844	unsigned int ctrl_reg;
 845	unsigned int isr_status;
 846
 847	id->p_recv_buf = NULL;
 848	id->p_send_buf = id->p_msg->buf;
 849	id->send_count = id->p_msg->len;
 850
 851	/* Set the controller in Master transmit mode and clear the FIFO. */
 852	ctrl_reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
 853	ctrl_reg &= ~CDNS_I2C_CR_RW;
 854	ctrl_reg |= CDNS_I2C_CR_CLR_FIFO;
 855
 856	/*
 857	 * Check for the message size against FIFO depth and set the
 858	 * 'hold bus' bit if it is greater than FIFO depth.
 859	 */
 860	if (id->send_count > id->fifo_depth)
 861		ctrl_reg |= CDNS_I2C_CR_HOLD;
 862	cdns_i2c_writereg(ctrl_reg, CDNS_I2C_CR_OFFSET);
 863
 864	/* Clear the interrupts in interrupt status register. */
 865	isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET);
 866	cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET);
 867
 868	/*
 869	 * Calculate the space available in FIFO. Check the message length
 870	 * against the space available, and fill the FIFO accordingly.
 871	 * Enable the interrupts.
 872	 */
 873	avail_bytes = id->fifo_depth -
 874				cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET);
 875
 876	if (id->send_count > avail_bytes)
 877		bytes_to_send = avail_bytes;
 878	else
 879		bytes_to_send = id->send_count;
 880
 881	while (bytes_to_send--) {
 882		cdns_i2c_writereg((*(id->p_send_buf)++), CDNS_I2C_DATA_OFFSET);
 883		id->send_count--;
 884	}
 885
 886	/*
 887	 * Clear the bus hold flag if there is no more data
 888	 * and if it is the last message.
 889	 */
 890	if (!id->bus_hold_flag && !id->send_count)
 891		cdns_i2c_clear_bus_hold(id);
 892	/* Set the slave address in address register - triggers operation. */
 893	cdns_i2c_writereg(id->p_msg->addr & CDNS_I2C_ADDR_MASK,
 894						CDNS_I2C_ADDR_OFFSET);
 895
 896	if (!id->atomic)
 897		cdns_i2c_writereg(CDNS_I2C_ENABLED_INTR_MASK, CDNS_I2C_IER_OFFSET);
 898	else if (id->send_count > 0)
 899		cdns_i2c_msend_rem_atomic(id);
 900}
 901
 902/**
 903 * cdns_i2c_master_reset - Reset the interface
 904 * @adap:	pointer to the i2c adapter driver instance
 905 *
 906 * This function cleanup the fifos, clear the hold bit and status
 907 * and disable the interrupts.
 908 */
 909static void cdns_i2c_master_reset(struct i2c_adapter *adap)
 910{
 911	struct cdns_i2c *id = adap->algo_data;
 912	u32 regval;
 913
 914	/* Disable the interrupts */
 915	cdns_i2c_writereg(CDNS_I2C_IXR_ALL_INTR_MASK, CDNS_I2C_IDR_OFFSET);
 916	/* Clear the hold bit and fifos */
 917	regval = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
 918	regval &= ~CDNS_I2C_CR_HOLD;
 919	regval |= CDNS_I2C_CR_CLR_FIFO;
 920	cdns_i2c_writereg(regval, CDNS_I2C_CR_OFFSET);
 921	/* Update the transfercount register to zero */
 922	cdns_i2c_writereg(0, CDNS_I2C_XFER_SIZE_OFFSET);
 923	/* Clear the interrupt status register */
 924	regval = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET);
 925	cdns_i2c_writereg(regval, CDNS_I2C_ISR_OFFSET);
 926	/* Clear the status register */
 927	regval = cdns_i2c_readreg(CDNS_I2C_SR_OFFSET);
 928	cdns_i2c_writereg(regval, CDNS_I2C_SR_OFFSET);
 929}
 930
 931static int cdns_i2c_process_msg(struct cdns_i2c *id, struct i2c_msg *msg,
 932		struct i2c_adapter *adap)
 933{
 934	unsigned long time_left, msg_timeout;
 935	u32 reg;
 936
 937	id->p_msg = msg;
 938	id->err_status = 0;
 939	if (!id->atomic)
 940		reinit_completion(&id->xfer_done);
 941
 942	/* Check for the TEN Bit mode on each msg */
 943	reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
 944	if (msg->flags & I2C_M_TEN) {
 945		if (reg & CDNS_I2C_CR_NEA)
 946			cdns_i2c_writereg(reg & ~CDNS_I2C_CR_NEA,
 947					CDNS_I2C_CR_OFFSET);
 948	} else {
 949		if (!(reg & CDNS_I2C_CR_NEA))
 950			cdns_i2c_writereg(reg | CDNS_I2C_CR_NEA,
 951					CDNS_I2C_CR_OFFSET);
 952	}
 953
 954	/* Check for the R/W flag on each msg */
 955	if (msg->flags & I2C_M_RD)
 956		cdns_i2c_mrecv(id);
 957	else
 958		cdns_i2c_msend(id);
 959
 960	/* Minimal time to execute this message */
 961	msg_timeout = msecs_to_jiffies((1000 * msg->len * BITS_PER_BYTE) / id->i2c_clk);
 962
 963	/*
 964	 * Plus some wiggle room.
 965	 * For non-atomic contexts, 500 ms is added to the timeout.
 966	 * For atomic contexts, 2000 ms is added because transfers happen in polled
 967	 * mode, requiring more time to account for the polling overhead.
 968	 */
 969	if (!id->atomic)
 970		msg_timeout += msecs_to_jiffies(500);
 971	else
 972		msg_timeout += msecs_to_jiffies(2000);
 973
 974	if (msg_timeout < adap->timeout)
 975		msg_timeout = adap->timeout;
 976
 977	if (!id->atomic) {
 978		/* Wait for the signal of completion */
 979		time_left = wait_for_completion_timeout(&id->xfer_done, msg_timeout);
 980	} else {
 981		/* 0 is success, -ETIMEDOUT is error */
 982		time_left = !readl_poll_timeout_atomic(id->membase + CDNS_I2C_ISR_OFFSET,
 983						       reg, (reg & CDNS_I2C_IXR_COMP),
 984						       CDNS_I2C_POLL_US_ATOMIC, msg_timeout);
 985	}
 986
 987	if (time_left == 0) {
 988		cdns_i2c_master_reset(adap);
 
 
 989		return -ETIMEDOUT;
 990	}
 991
 992	cdns_i2c_writereg(CDNS_I2C_IXR_ALL_INTR_MASK,
 993			  CDNS_I2C_IDR_OFFSET);
 994
 995	/* If it is bus arbitration error, try again */
 996	if (id->err_status & CDNS_I2C_IXR_ARB_LOST)
 997		return -EAGAIN;
 998
 999	if (msg->flags & I2C_M_RECV_LEN)
1000		msg->len += min_t(unsigned int, msg->buf[0], I2C_SMBUS_BLOCK_MAX);
1001
1002	return 0;
1003}
1004
1005static int cdns_i2c_master_common_xfer(struct i2c_adapter *adap,
1006				       struct i2c_msg *msgs,
1007				       int num)
 
 
 
 
 
 
 
 
 
1008{
1009	int ret, count;
1010	u32 reg;
1011	struct cdns_i2c *id = adap->algo_data;
1012	bool hold_quirk;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1013
1014	/* Check if the bus is free */
1015	if (!id->atomic)
1016		ret = readl_relaxed_poll_timeout(id->membase + CDNS_I2C_SR_OFFSET,
1017						 reg,
1018						 !(reg & CDNS_I2C_SR_BA),
1019						 CDNS_I2C_POLL_US, CDNS_I2C_TIMEOUT_US);
1020	else
1021		ret = readl_poll_timeout_atomic(id->membase + CDNS_I2C_SR_OFFSET,
1022						reg,
1023						!(reg & CDNS_I2C_SR_BA),
1024						CDNS_I2C_POLL_US_ATOMIC, CDNS_I2C_TIMEOUT_US);
1025	if (ret) {
1026		ret = -EAGAIN;
1027		if (id->adap.bus_recovery_info)
1028			i2c_recover_bus(adap);
1029		return ret;
1030	}
1031
1032	hold_quirk = !!(id->quirks & CDNS_I2C_BROKEN_HOLD_BIT);
1033	/*
1034	 * Set the flag to one when multiple messages are to be
1035	 * processed with a repeated start.
1036	 */
1037	if (num > 1) {
1038		/*
1039		 * This controller does not give completion interrupt after a
1040		 * master receive message if HOLD bit is set (repeated start),
1041		 * resulting in SW timeout. Hence, if a receive message is
1042		 * followed by any other message, an error is returned
1043		 * indicating that this sequence is not supported.
1044		 */
1045		for (count = 0; (count < num - 1 && hold_quirk); count++) {
1046			if (msgs[count].flags & I2C_M_RD) {
1047				dev_warn(adap->dev.parent,
1048					 "Can't do repeated start after a receive message\n");
1049				return -EOPNOTSUPP;
 
1050			}
1051		}
1052		id->bus_hold_flag = 1;
1053		reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
1054		reg |= CDNS_I2C_CR_HOLD;
1055		cdns_i2c_writereg(reg, CDNS_I2C_CR_OFFSET);
1056	} else {
1057		id->bus_hold_flag = 0;
1058	}
1059
1060	/* Process the msg one by one */
1061	for (count = 0; count < num; count++, msgs++) {
1062		if (count == (num - 1))
1063			id->bus_hold_flag = 0;
1064
1065		ret = cdns_i2c_process_msg(id, msgs, adap);
1066		if (ret)
1067			return ret;
1068
1069		/* Report the other error interrupts to application */
1070		if (id->err_status || id->err_status_atomic) {
1071			cdns_i2c_master_reset(adap);
1072
1073			if (id->err_status & CDNS_I2C_IXR_NACK)
1074				return -ENXIO;
1075
1076			return -EIO;
1077		}
1078	}
1079	return 0;
1080}
1081
1082/**
1083 * cdns_i2c_master_xfer - The main i2c transfer function
1084 * @adap:	pointer to the i2c adapter driver instance
1085 * @msgs:	pointer to the i2c message structure
1086 * @num:	the number of messages to transfer
1087 *
1088 * Initiates the send/recv activity based on the transfer message received.
1089 *
1090 * Return: number of msgs processed on success, negative error otherwise
1091 */
1092static int cdns_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
1093				int num)
1094{
1095	int ret;
1096	struct cdns_i2c *id = adap->algo_data;
1097#if IS_ENABLED(CONFIG_I2C_SLAVE)
1098	bool change_role = false;
1099#endif
1100
1101	ret = pm_runtime_resume_and_get(id->dev);
1102	if (ret < 0)
1103		return ret;
1104
1105#if IS_ENABLED(CONFIG_I2C_SLAVE)
1106	/* Check i2c operating mode and switch if possible */
1107	if (id->dev_mode == CDNS_I2C_MODE_SLAVE) {
1108		if (id->slave_state != CDNS_I2C_SLAVE_STATE_IDLE) {
1109			ret = -EAGAIN;
1110			goto out;
1111		}
 
1112
1113		/* Set mode to master */
1114		cdns_i2c_set_mode(CDNS_I2C_MODE_MASTER, id);
1115
1116		/* Mark flag to change role once xfer is completed */
1117		change_role = true;
1118	}
1119#endif
1120
1121	ret = cdns_i2c_master_common_xfer(adap, msgs, num);
1122	if (!ret)
1123		ret = num;
1124#if IS_ENABLED(CONFIG_I2C_SLAVE)
1125out:
1126	/* Switch i2c mode to slave */
1127	if (change_role)
1128		cdns_i2c_set_mode(CDNS_I2C_MODE_SLAVE, id);
1129#endif
1130
1131	pm_runtime_mark_last_busy(id->dev);
1132	pm_runtime_put_autosuspend(id->dev);
1133	return ret;
1134}
1135
1136/**
1137 * cdns_i2c_master_xfer_atomic - The i2c transfer function in atomic mode
1138 * @adap:	pointer to the i2c adapter driver instance
1139 * @msgs:	pointer to the i2c message structure
1140 * @num:	the number of messages to transfer
1141 *
1142 * Return: number of msgs processed on success, negative error otherwise
1143 */
1144static int cdns_i2c_master_xfer_atomic(struct i2c_adapter *adap, struct i2c_msg *msgs,
1145				       int num)
1146{
1147	int ret;
1148	struct cdns_i2c *id = adap->algo_data;
1149
1150	ret = cdns_i2c_runtime_resume(id->dev);
1151	if (ret)
1152		return ret;
1153
1154	if (id->quirks & CDNS_I2C_BROKEN_HOLD_BIT) {
1155		dev_warn(id->adap.dev.parent,
1156			 "Atomic xfer not supported for version 1.0\n");
1157		return 0;
1158	}
1159
1160	id->atomic = true;
1161	ret = cdns_i2c_master_common_xfer(adap, msgs, num);
1162	if (!ret)
1163		ret = num;
1164
1165	id->atomic = false;
1166	cdns_i2c_runtime_suspend(id->dev);
1167
1168	return ret;
1169}
1170
1171/**
1172 * cdns_i2c_func - Returns the supported features of the I2C driver
1173 * @adap:	pointer to the i2c adapter structure
1174 *
1175 * Return: 32 bit value, each bit corresponding to a feature
1176 */
1177static u32 cdns_i2c_func(struct i2c_adapter *adap)
1178{
1179	u32 func = I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR |
1180			(I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK) |
1181			I2C_FUNC_SMBUS_BLOCK_DATA;
1182
1183#if IS_ENABLED(CONFIG_I2C_SLAVE)
1184	func |= I2C_FUNC_SLAVE;
1185#endif
1186
1187	return func;
1188}
1189
1190#if IS_ENABLED(CONFIG_I2C_SLAVE)
1191static int cdns_reg_slave(struct i2c_client *slave)
1192{
1193	int ret;
1194	struct cdns_i2c *id = container_of(slave->adapter, struct cdns_i2c,
1195									adap);
1196
1197	if (id->slave)
1198		return -EBUSY;
1199
1200	if (slave->flags & I2C_CLIENT_TEN)
1201		return -EAFNOSUPPORT;
1202
1203	ret = pm_runtime_resume_and_get(id->dev);
1204	if (ret < 0)
1205		return ret;
1206
1207	/* Store slave information */
1208	id->slave = slave;
1209
1210	/* Enable I2C slave */
1211	cdns_i2c_set_mode(CDNS_I2C_MODE_SLAVE, id);
1212
1213	return 0;
1214}
1215
1216static int cdns_unreg_slave(struct i2c_client *slave)
1217{
1218	struct cdns_i2c *id = container_of(slave->adapter, struct cdns_i2c,
1219									adap);
1220
1221	pm_runtime_put(id->dev);
1222
1223	/* Remove slave information */
1224	id->slave = NULL;
1225
1226	/* Enable I2C master */
1227	cdns_i2c_set_mode(CDNS_I2C_MODE_MASTER, id);
1228
1229	return 0;
1230}
1231#endif
1232
1233static const struct i2c_algorithm cdns_i2c_algo = {
1234	.master_xfer	= cdns_i2c_master_xfer,
1235	.master_xfer_atomic = cdns_i2c_master_xfer_atomic,
1236	.functionality	= cdns_i2c_func,
1237#if IS_ENABLED(CONFIG_I2C_SLAVE)
1238	.reg_slave	= cdns_reg_slave,
1239	.unreg_slave	= cdns_unreg_slave,
1240#endif
1241};
1242
1243/**
1244 * cdns_i2c_calc_divs - Calculate clock dividers
1245 * @f:		I2C clock frequency
1246 * @input_clk:	Input clock frequency
1247 * @a:		First divider (return value)
1248 * @b:		Second divider (return value)
1249 *
1250 * f is used as input and output variable. As input it is used as target I2C
1251 * frequency. On function exit f holds the actually resulting I2C frequency.
1252 *
1253 * Return: 0 on success, negative errno otherwise.
1254 */
1255static int cdns_i2c_calc_divs(unsigned long *f, unsigned long input_clk,
1256		unsigned int *a, unsigned int *b)
1257{
1258	unsigned long fscl = *f, best_fscl = *f, actual_fscl, temp;
1259	unsigned int div_a, div_b, calc_div_a = 0, calc_div_b = 0;
1260	unsigned int last_error, current_error;
1261
1262	/* calculate (divisor_a+1) x (divisor_b+1) */
1263	temp = input_clk / (22 * fscl);
1264
1265	/*
1266	 * If the calculated value is negative or 0, the fscl input is out of
1267	 * range. Return error.
1268	 */
1269	if (!temp || (temp > (CDNS_I2C_DIVA_MAX * CDNS_I2C_DIVB_MAX)))
1270		return -EINVAL;
1271
1272	last_error = -1;
1273	for (div_a = 0; div_a < CDNS_I2C_DIVA_MAX; div_a++) {
1274		div_b = DIV_ROUND_UP(input_clk, 22 * fscl * (div_a + 1));
1275
1276		if ((div_b < 1) || (div_b > CDNS_I2C_DIVB_MAX))
1277			continue;
1278		div_b--;
1279
1280		actual_fscl = input_clk / (22 * (div_a + 1) * (div_b + 1));
1281
1282		if (actual_fscl > fscl)
1283			continue;
1284
1285		current_error = fscl - actual_fscl;
1286
1287		if (last_error > current_error) {
1288			calc_div_a = div_a;
1289			calc_div_b = div_b;
1290			best_fscl = actual_fscl;
1291			last_error = current_error;
1292		}
1293	}
1294
1295	*a = calc_div_a;
1296	*b = calc_div_b;
1297	*f = best_fscl;
1298
1299	return 0;
1300}
1301
1302/**
1303 * cdns_i2c_setclk - This function sets the serial clock rate for the I2C device
1304 * @clk_in:	I2C clock input frequency in Hz
1305 * @id:		Pointer to the I2C device structure
1306 *
1307 * The device must be idle rather than busy transferring data before setting
1308 * these device options.
1309 * The data rate is set by values in the control register.
1310 * The formula for determining the correct register values is
1311 *	Fscl = Fpclk/(22 x (divisor_a+1) x (divisor_b+1))
1312 * See the hardware data sheet for a full explanation of setting the serial
1313 * clock rate. The clock can not be faster than the input clock divide by 22.
1314 * The two most common clock rates are 100KHz and 400KHz.
1315 *
1316 * Return: 0 on success, negative error otherwise
1317 */
1318static int cdns_i2c_setclk(unsigned long clk_in, struct cdns_i2c *id)
1319{
1320	unsigned int div_a, div_b;
1321	unsigned int ctrl_reg;
1322	int ret = 0;
1323	unsigned long fscl = id->i2c_clk;
1324
1325	ret = cdns_i2c_calc_divs(&fscl, clk_in, &div_a, &div_b);
1326	if (ret)
1327		return ret;
1328
1329	ctrl_reg = id->ctrl_reg;
1330	ctrl_reg &= ~(CDNS_I2C_CR_DIVA_MASK | CDNS_I2C_CR_DIVB_MASK);
1331	ctrl_reg |= ((div_a << CDNS_I2C_CR_DIVA_SHIFT) |
1332			(div_b << CDNS_I2C_CR_DIVB_SHIFT));
1333	id->ctrl_reg = ctrl_reg;
1334	cdns_i2c_writereg(ctrl_reg, CDNS_I2C_CR_OFFSET);
1335#if IS_ENABLED(CONFIG_I2C_SLAVE)
1336	id->ctrl_reg_diva_divb = ctrl_reg & (CDNS_I2C_CR_DIVA_MASK |
1337				 CDNS_I2C_CR_DIVB_MASK);
1338#endif
1339	return 0;
1340}
1341
1342/**
1343 * cdns_i2c_clk_notifier_cb - Clock rate change callback
1344 * @nb:		Pointer to notifier block
1345 * @event:	Notification reason
1346 * @data:	Pointer to notification data object
1347 *
1348 * This function is called when the cdns_i2c input clock frequency changes.
1349 * The callback checks whether a valid bus frequency can be generated after the
1350 * change. If so, the change is acknowledged, otherwise the change is aborted.
1351 * New dividers are written to the HW in the pre- or post change notification
1352 * depending on the scaling direction.
1353 *
1354 * Return:	NOTIFY_STOP if the rate change should be aborted, NOTIFY_OK
1355 *		to acknowledge the change, NOTIFY_DONE if the notification is
1356 *		considered irrelevant.
1357 */
1358static int cdns_i2c_clk_notifier_cb(struct notifier_block *nb, unsigned long
1359		event, void *data)
1360{
1361	struct clk_notifier_data *ndata = data;
1362	struct cdns_i2c *id = to_cdns_i2c(nb);
1363
1364	if (pm_runtime_suspended(id->dev))
1365		return NOTIFY_OK;
1366
1367	switch (event) {
1368	case PRE_RATE_CHANGE:
1369	{
1370		unsigned long input_clk = ndata->new_rate;
1371		unsigned long fscl = id->i2c_clk;
1372		unsigned int div_a, div_b;
1373		int ret;
1374
1375		ret = cdns_i2c_calc_divs(&fscl, input_clk, &div_a, &div_b);
1376		if (ret) {
1377			dev_warn(id->adap.dev.parent,
1378					"clock rate change rejected\n");
1379			return NOTIFY_STOP;
1380		}
1381
1382		/* scale up */
1383		if (ndata->new_rate > ndata->old_rate)
1384			cdns_i2c_setclk(ndata->new_rate, id);
1385
1386		return NOTIFY_OK;
1387	}
1388	case POST_RATE_CHANGE:
1389		id->input_clk = ndata->new_rate;
1390		/* scale down */
1391		if (ndata->new_rate < ndata->old_rate)
1392			cdns_i2c_setclk(ndata->new_rate, id);
1393		return NOTIFY_OK;
1394	case ABORT_RATE_CHANGE:
1395		/* scale up */
1396		if (ndata->new_rate > ndata->old_rate)
1397			cdns_i2c_setclk(ndata->old_rate, id);
1398		return NOTIFY_OK;
1399	default:
1400		return NOTIFY_DONE;
1401	}
1402}
1403
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1404static int __maybe_unused cdns_i2c_suspend(struct device *dev)
1405{
1406	struct cdns_i2c *xi2c = dev_get_drvdata(dev);
1407
1408	i2c_mark_adapter_suspended(&xi2c->adap);
1409
1410	if (!pm_runtime_status_suspended(dev))
1411		return cdns_i2c_runtime_suspend(dev);
1412
1413	return 0;
1414}
1415
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1416static int __maybe_unused cdns_i2c_resume(struct device *dev)
1417{
1418	struct cdns_i2c *xi2c = dev_get_drvdata(dev);
1419	int err;
1420
1421	err = cdns_i2c_runtime_resume(dev);
1422	if (err)
1423		return err;
1424
1425	if (pm_runtime_status_suspended(dev)) {
1426		err = cdns_i2c_runtime_suspend(dev);
1427		if (err)
1428			return err;
1429	}
1430
1431	i2c_mark_adapter_resumed(&xi2c->adap);
1432
1433	return 0;
1434}
1435
1436static const struct dev_pm_ops cdns_i2c_dev_pm_ops = {
1437	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(cdns_i2c_suspend, cdns_i2c_resume)
1438	SET_RUNTIME_PM_OPS(cdns_i2c_runtime_suspend,
1439			   cdns_i2c_runtime_resume, NULL)
1440};
1441
1442static const struct cdns_platform_data r1p10_i2c_def = {
1443	.quirks = CDNS_I2C_BROKEN_HOLD_BIT,
1444};
1445
1446static const struct of_device_id cdns_i2c_of_match[] = {
1447	{ .compatible = "cdns,i2c-r1p10", .data = &r1p10_i2c_def },
1448	{ .compatible = "cdns,i2c-r1p14",},
1449	{ /* end of table */ }
1450};
1451MODULE_DEVICE_TABLE(of, cdns_i2c_of_match);
1452
1453/**
1454 * cdns_i2c_detect_transfer_size - Detect the maximum transfer size supported
1455 * @id: Device private data structure
1456 *
1457 * Detect the maximum transfer size that is supported by this instance of the
1458 * Cadence I2C controller.
1459 */
1460static void cdns_i2c_detect_transfer_size(struct cdns_i2c *id)
1461{
1462	u32 val;
1463
1464	/*
1465	 * Writing to the transfer size register is only possible if these two bits
1466	 * are set in the control register.
1467	 */
1468	cdns_i2c_writereg(CDNS_I2C_CR_MS | CDNS_I2C_CR_RW, CDNS_I2C_CR_OFFSET);
1469
1470	/*
1471	 * The number of writable bits of the transfer size register can be between
1472	 * 4 and 8. This is a controlled through a synthesis parameter of the IP
1473	 * core and can vary from instance to instance. The unused MSBs always read
1474	 * back as 0. Writing 0xff and then reading the value back will report the
1475	 * maximum supported transfer size.
1476	 */
1477	cdns_i2c_writereg(CDNS_I2C_MAX_TRANSFER_SIZE, CDNS_I2C_XFER_SIZE_OFFSET);
1478	val = cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET);
1479	id->transfer_size = CDNS_I2C_TRANSFER_SIZE(val);
1480	cdns_i2c_writereg(0, CDNS_I2C_XFER_SIZE_OFFSET);
1481	cdns_i2c_writereg(0, CDNS_I2C_CR_OFFSET);
1482}
1483
1484/**
1485 * cdns_i2c_probe - Platform registration call
1486 * @pdev:	Handle to the platform device structure
1487 *
1488 * This function does all the memory allocation and registration for the i2c
1489 * device. User can modify the address mode to 10 bit address mode using the
1490 * ioctl call with option I2C_TENBIT.
1491 *
1492 * Return: 0 on success, negative error otherwise
1493 */
1494static int cdns_i2c_probe(struct platform_device *pdev)
1495{
1496	struct resource *r_mem;
1497	struct cdns_i2c *id;
1498	int ret, irq;
1499	const struct of_device_id *match;
1500
1501	id = devm_kzalloc(&pdev->dev, sizeof(*id), GFP_KERNEL);
1502	if (!id)
1503		return -ENOMEM;
1504
1505	id->dev = &pdev->dev;
1506	platform_set_drvdata(pdev, id);
1507
1508	match = of_match_node(cdns_i2c_of_match, pdev->dev.of_node);
1509	if (match && match->data) {
1510		const struct cdns_platform_data *data = match->data;
1511		id->quirks = data->quirks;
1512	}
1513
1514	id->rinfo.pinctrl = devm_pinctrl_get(&pdev->dev);
1515	if (IS_ERR(id->rinfo.pinctrl)) {
1516		int err = PTR_ERR(id->rinfo.pinctrl);
1517
1518		dev_info(&pdev->dev, "can't get pinctrl, bus recovery not supported\n");
1519		if (err != -ENODEV)
1520			return err;
1521	} else {
1522		id->adap.bus_recovery_info = &id->rinfo;
1523	}
1524
1525	id->membase = devm_platform_get_and_ioremap_resource(pdev, 0, &r_mem);
1526	if (IS_ERR(id->membase))
1527		return PTR_ERR(id->membase);
1528
1529	irq = platform_get_irq(pdev, 0);
1530	if (irq < 0)
1531		return irq;
1532
1533	id->adap.owner = THIS_MODULE;
1534	id->adap.dev.of_node = pdev->dev.of_node;
1535	id->adap.algo = &cdns_i2c_algo;
1536	id->adap.timeout = CDNS_I2C_TIMEOUT;
1537	id->adap.retries = 3;		/* Default retry value. */
1538	id->adap.algo_data = id;
1539	id->adap.dev.parent = &pdev->dev;
1540	init_completion(&id->xfer_done);
1541	snprintf(id->adap.name, sizeof(id->adap.name),
1542		 "Cadence I2C at %08lx", (unsigned long)r_mem->start);
1543
1544	id->clk = devm_clk_get(&pdev->dev, NULL);
1545	if (IS_ERR(id->clk))
1546		return dev_err_probe(&pdev->dev, PTR_ERR(id->clk),
1547				     "input clock not found.\n");
1548
1549	id->reset = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
1550	if (IS_ERR(id->reset))
1551		return dev_err_probe(&pdev->dev, PTR_ERR(id->reset),
1552				     "Failed to request reset.\n");
1553
1554	ret = clk_prepare_enable(id->clk);
1555	if (ret)
1556		dev_err(&pdev->dev, "Unable to enable clock.\n");
1557
1558	ret = reset_control_deassert(id->reset);
1559	if (ret) {
1560		dev_err_probe(&pdev->dev, ret,
1561			      "Failed to de-assert reset.\n");
1562		goto err_clk_dis;
1563	}
1564
1565	pm_runtime_set_autosuspend_delay(id->dev, CNDS_I2C_PM_TIMEOUT);
1566	pm_runtime_use_autosuspend(id->dev);
1567	pm_runtime_set_active(id->dev);
1568	pm_runtime_enable(id->dev);
1569
1570	id->clk_rate_change_nb.notifier_call = cdns_i2c_clk_notifier_cb;
1571	if (clk_notifier_register(id->clk, &id->clk_rate_change_nb))
1572		dev_warn(&pdev->dev, "Unable to register clock notifier.\n");
1573	id->input_clk = clk_get_rate(id->clk);
1574
1575	ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
1576			&id->i2c_clk);
1577	if (ret || (id->i2c_clk > I2C_MAX_FAST_MODE_FREQ))
1578		id->i2c_clk = I2C_MAX_STANDARD_MODE_FREQ;
1579
1580#if IS_ENABLED(CONFIG_I2C_SLAVE)
1581	/* Set initial mode to master */
1582	id->dev_mode = CDNS_I2C_MODE_MASTER;
1583	id->slave_state = CDNS_I2C_SLAVE_STATE_IDLE;
1584#endif
1585	id->ctrl_reg = CDNS_I2C_CR_ACK_EN | CDNS_I2C_CR_NEA | CDNS_I2C_CR_MS;
1586
1587	id->fifo_depth = CDNS_I2C_FIFO_DEPTH_DEFAULT;
1588	of_property_read_u32(pdev->dev.of_node, "fifo-depth", &id->fifo_depth);
1589
1590	cdns_i2c_detect_transfer_size(id);
1591
1592	ret = cdns_i2c_setclk(id->input_clk, id);
1593	if (ret) {
1594		dev_err(&pdev->dev, "invalid SCL clock: %u Hz\n", id->i2c_clk);
1595		ret = -EINVAL;
1596		goto err_clk_notifier_unregister;
1597	}
1598
1599	ret = devm_request_irq(&pdev->dev, irq, cdns_i2c_isr, 0,
1600				 DRIVER_NAME, id);
1601	if (ret) {
1602		dev_err(&pdev->dev, "cannot get irq %d\n", irq);
1603		goto err_clk_notifier_unregister;
1604	}
1605	cdns_i2c_init(id);
1606
1607	ret = i2c_add_adapter(&id->adap);
1608	if (ret < 0)
1609		goto err_clk_notifier_unregister;
1610
1611	dev_info(&pdev->dev, "%u kHz mmio %08lx irq %d\n",
1612		 id->i2c_clk / 1000, (unsigned long)r_mem->start, irq);
1613
1614	return 0;
1615
1616err_clk_notifier_unregister:
1617	clk_notifier_unregister(id->clk, &id->clk_rate_change_nb);
1618	reset_control_assert(id->reset);
1619err_clk_dis:
1620	clk_disable_unprepare(id->clk);
1621	pm_runtime_disable(&pdev->dev);
1622	pm_runtime_set_suspended(&pdev->dev);
1623	return ret;
1624}
1625
1626/**
1627 * cdns_i2c_remove - Unregister the device after releasing the resources
1628 * @pdev:	Handle to the platform device structure
1629 *
1630 * This function frees all the resources allocated to the device.
1631 *
1632 * Return: 0 always
1633 */
1634static void cdns_i2c_remove(struct platform_device *pdev)
1635{
1636	struct cdns_i2c *id = platform_get_drvdata(pdev);
1637
1638	pm_runtime_disable(&pdev->dev);
1639	pm_runtime_set_suspended(&pdev->dev);
1640	pm_runtime_dont_use_autosuspend(&pdev->dev);
1641
1642	i2c_del_adapter(&id->adap);
1643	clk_notifier_unregister(id->clk, &id->clk_rate_change_nb);
1644	reset_control_assert(id->reset);
1645	clk_disable_unprepare(id->clk);
1646}
1647
1648static struct platform_driver cdns_i2c_drv = {
1649	.driver = {
1650		.name  = DRIVER_NAME,
1651		.of_match_table = cdns_i2c_of_match,
1652		.pm = &cdns_i2c_dev_pm_ops,
1653	},
1654	.probe  = cdns_i2c_probe,
1655	.remove = cdns_i2c_remove,
1656};
1657
1658module_platform_driver(cdns_i2c_drv);
1659
1660MODULE_AUTHOR("Xilinx Inc.");
1661MODULE_DESCRIPTION("Cadence I2C bus driver");
1662MODULE_LICENSE("GPL");