cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
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i2c-uniphier-f.c (18180B)


      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
      4 */
      5
      6#include <linux/clk.h>
      7#include <linux/i2c.h>
      8#include <linux/iopoll.h>
      9#include <linux/interrupt.h>
     10#include <linux/io.h>
     11#include <linux/module.h>
     12#include <linux/platform_device.h>
     13
     14#define UNIPHIER_FI2C_CR	0x00	/* control register */
     15#define     UNIPHIER_FI2C_CR_MST	BIT(3)	/* master mode */
     16#define     UNIPHIER_FI2C_CR_STA	BIT(2)	/* start condition */
     17#define     UNIPHIER_FI2C_CR_STO	BIT(1)	/* stop condition */
     18#define     UNIPHIER_FI2C_CR_NACK	BIT(0)	/* do not return ACK */
     19#define UNIPHIER_FI2C_DTTX	0x04	/* TX FIFO */
     20#define     UNIPHIER_FI2C_DTTX_CMD	BIT(8)	/* send command (slave addr) */
     21#define     UNIPHIER_FI2C_DTTX_RD	BIT(0)	/* read transaction */
     22#define UNIPHIER_FI2C_DTRX	0x04	/* RX FIFO */
     23#define UNIPHIER_FI2C_SLAD	0x0c	/* slave address */
     24#define UNIPHIER_FI2C_CYC	0x10	/* clock cycle control */
     25#define UNIPHIER_FI2C_LCTL	0x14	/* clock low period control */
     26#define UNIPHIER_FI2C_SSUT	0x18	/* restart/stop setup time control */
     27#define UNIPHIER_FI2C_DSUT	0x1c	/* data setup time control */
     28#define UNIPHIER_FI2C_INT	0x20	/* interrupt status */
     29#define UNIPHIER_FI2C_IE	0x24	/* interrupt enable */
     30#define UNIPHIER_FI2C_IC	0x28	/* interrupt clear */
     31#define     UNIPHIER_FI2C_INT_TE	BIT(9)	/* TX FIFO empty */
     32#define     UNIPHIER_FI2C_INT_RF	BIT(8)	/* RX FIFO full */
     33#define     UNIPHIER_FI2C_INT_TC	BIT(7)	/* send complete (STOP) */
     34#define     UNIPHIER_FI2C_INT_RC	BIT(6)	/* receive complete (STOP) */
     35#define     UNIPHIER_FI2C_INT_TB	BIT(5)	/* sent specified bytes */
     36#define     UNIPHIER_FI2C_INT_RB	BIT(4)	/* received specified bytes */
     37#define     UNIPHIER_FI2C_INT_NA	BIT(2)	/* no ACK */
     38#define     UNIPHIER_FI2C_INT_AL	BIT(1)	/* arbitration lost */
     39#define UNIPHIER_FI2C_SR	0x2c	/* status register */
     40#define     UNIPHIER_FI2C_SR_DB		BIT(12)	/* device busy */
     41#define     UNIPHIER_FI2C_SR_STS	BIT(11)	/* stop condition detected */
     42#define     UNIPHIER_FI2C_SR_BB		BIT(8)	/* bus busy */
     43#define     UNIPHIER_FI2C_SR_RFF	BIT(3)	/* RX FIFO full */
     44#define     UNIPHIER_FI2C_SR_RNE	BIT(2)	/* RX FIFO not empty */
     45#define     UNIPHIER_FI2C_SR_TNF	BIT(1)	/* TX FIFO not full */
     46#define     UNIPHIER_FI2C_SR_TFE	BIT(0)	/* TX FIFO empty */
     47#define UNIPHIER_FI2C_RST	0x34	/* reset control */
     48#define     UNIPHIER_FI2C_RST_TBRST	BIT(2)	/* clear TX FIFO */
     49#define     UNIPHIER_FI2C_RST_RBRST	BIT(1)	/* clear RX FIFO */
     50#define     UNIPHIER_FI2C_RST_RST	BIT(0)	/* forcible bus reset */
     51#define UNIPHIER_FI2C_BM	0x38	/* bus monitor */
     52#define     UNIPHIER_FI2C_BM_SDAO	BIT(3)	/* output for SDA line */
     53#define     UNIPHIER_FI2C_BM_SDAS	BIT(2)	/* readback of SDA line */
     54#define     UNIPHIER_FI2C_BM_SCLO	BIT(1)	/* output for SCL line */
     55#define     UNIPHIER_FI2C_BM_SCLS	BIT(0)	/* readback of SCL line */
     56#define UNIPHIER_FI2C_NOISE	0x3c	/* noise filter control */
     57#define UNIPHIER_FI2C_TBC	0x40	/* TX byte count setting */
     58#define UNIPHIER_FI2C_RBC	0x44	/* RX byte count setting */
     59#define UNIPHIER_FI2C_TBCM	0x48	/* TX byte count monitor */
     60#define UNIPHIER_FI2C_RBCM	0x4c	/* RX byte count monitor */
     61#define UNIPHIER_FI2C_BRST	0x50	/* bus reset */
     62#define     UNIPHIER_FI2C_BRST_FOEN	BIT(1)	/* normal operation */
     63#define     UNIPHIER_FI2C_BRST_RSCL	BIT(0)	/* release SCL */
     64
     65#define UNIPHIER_FI2C_INT_FAULTS	\
     66				(UNIPHIER_FI2C_INT_NA | UNIPHIER_FI2C_INT_AL)
     67#define UNIPHIER_FI2C_INT_STOP		\
     68				(UNIPHIER_FI2C_INT_TC | UNIPHIER_FI2C_INT_RC)
     69
     70#define UNIPHIER_FI2C_RD		BIT(0)
     71#define UNIPHIER_FI2C_STOP		BIT(1)
     72#define UNIPHIER_FI2C_MANUAL_NACK	BIT(2)
     73#define UNIPHIER_FI2C_BYTE_WISE		BIT(3)
     74#define UNIPHIER_FI2C_DEFER_STOP_COMP	BIT(4)
     75
     76#define UNIPHIER_FI2C_FIFO_SIZE		8
     77
     78struct uniphier_fi2c_priv {
     79	struct completion comp;
     80	struct i2c_adapter adap;
     81	void __iomem *membase;
     82	struct clk *clk;
     83	unsigned int len;
     84	u8 *buf;
     85	u32 enabled_irqs;
     86	int error;
     87	unsigned int flags;
     88	unsigned int busy_cnt;
     89	unsigned int clk_cycle;
     90	spinlock_t lock;	/* IRQ synchronization */
     91};
     92
     93static void uniphier_fi2c_fill_txfifo(struct uniphier_fi2c_priv *priv,
     94				      bool first)
     95{
     96	int fifo_space = UNIPHIER_FI2C_FIFO_SIZE;
     97
     98	/*
     99	 * TX-FIFO stores slave address in it for the first access.
    100	 * Decrement the counter.
    101	 */
    102	if (first)
    103		fifo_space--;
    104
    105	while (priv->len) {
    106		if (fifo_space-- <= 0)
    107			break;
    108
    109		writel(*priv->buf++, priv->membase + UNIPHIER_FI2C_DTTX);
    110		priv->len--;
    111	}
    112}
    113
    114static void uniphier_fi2c_drain_rxfifo(struct uniphier_fi2c_priv *priv)
    115{
    116	int fifo_left = priv->flags & UNIPHIER_FI2C_BYTE_WISE ?
    117						1 : UNIPHIER_FI2C_FIFO_SIZE;
    118
    119	while (priv->len) {
    120		if (fifo_left-- <= 0)
    121			break;
    122
    123		*priv->buf++ = readl(priv->membase + UNIPHIER_FI2C_DTRX);
    124		priv->len--;
    125	}
    126}
    127
    128static void uniphier_fi2c_set_irqs(struct uniphier_fi2c_priv *priv)
    129{
    130	writel(priv->enabled_irqs, priv->membase + UNIPHIER_FI2C_IE);
    131}
    132
    133static void uniphier_fi2c_clear_irqs(struct uniphier_fi2c_priv *priv,
    134				     u32 mask)
    135{
    136	writel(mask, priv->membase + UNIPHIER_FI2C_IC);
    137}
    138
    139static void uniphier_fi2c_stop(struct uniphier_fi2c_priv *priv)
    140{
    141	priv->enabled_irqs |= UNIPHIER_FI2C_INT_STOP;
    142	uniphier_fi2c_set_irqs(priv);
    143	writel(UNIPHIER_FI2C_CR_MST | UNIPHIER_FI2C_CR_STO,
    144	       priv->membase + UNIPHIER_FI2C_CR);
    145}
    146
    147static irqreturn_t uniphier_fi2c_interrupt(int irq, void *dev_id)
    148{
    149	struct uniphier_fi2c_priv *priv = dev_id;
    150	u32 irq_status;
    151
    152	spin_lock(&priv->lock);
    153
    154	irq_status = readl(priv->membase + UNIPHIER_FI2C_INT);
    155	irq_status &= priv->enabled_irqs;
    156
    157	if (irq_status & UNIPHIER_FI2C_INT_STOP)
    158		goto complete;
    159
    160	if (unlikely(irq_status & UNIPHIER_FI2C_INT_AL)) {
    161		priv->error = -EAGAIN;
    162		goto complete;
    163	}
    164
    165	if (unlikely(irq_status & UNIPHIER_FI2C_INT_NA)) {
    166		priv->error = -ENXIO;
    167		if (priv->flags & UNIPHIER_FI2C_RD) {
    168			/*
    169			 * work around a hardware bug:
    170			 * The receive-completed interrupt is never set even if
    171			 * STOP condition is detected after the address phase
    172			 * of read transaction fails to get ACK.
    173			 * To avoid time-out error, we issue STOP here,
    174			 * but do not wait for its completion.
    175			 * It should be checked after exiting this handler.
    176			 */
    177			uniphier_fi2c_stop(priv);
    178			priv->flags |= UNIPHIER_FI2C_DEFER_STOP_COMP;
    179			goto complete;
    180		}
    181		goto stop;
    182	}
    183
    184	if (irq_status & UNIPHIER_FI2C_INT_TE) {
    185		if (!priv->len)
    186			goto data_done;
    187
    188		uniphier_fi2c_fill_txfifo(priv, false);
    189		goto handled;
    190	}
    191
    192	if (irq_status & (UNIPHIER_FI2C_INT_RF | UNIPHIER_FI2C_INT_RB)) {
    193		uniphier_fi2c_drain_rxfifo(priv);
    194		/*
    195		 * If the number of bytes to read is multiple of the FIFO size
    196		 * (msg->len == 8, 16, 24, ...), the INT_RF bit is set a little
    197		 * earlier than INT_RB. We wait for INT_RB to confirm the
    198		 * completion of the current message.
    199		 */
    200		if (!priv->len && (irq_status & UNIPHIER_FI2C_INT_RB))
    201			goto data_done;
    202
    203		if (unlikely(priv->flags & UNIPHIER_FI2C_MANUAL_NACK)) {
    204			if (priv->len <= UNIPHIER_FI2C_FIFO_SIZE &&
    205			    !(priv->flags & UNIPHIER_FI2C_BYTE_WISE)) {
    206				priv->enabled_irqs |= UNIPHIER_FI2C_INT_RB;
    207				uniphier_fi2c_set_irqs(priv);
    208				priv->flags |= UNIPHIER_FI2C_BYTE_WISE;
    209			}
    210			if (priv->len <= 1)
    211				writel(UNIPHIER_FI2C_CR_MST |
    212				       UNIPHIER_FI2C_CR_NACK,
    213				       priv->membase + UNIPHIER_FI2C_CR);
    214		}
    215
    216		goto handled;
    217	}
    218
    219	spin_unlock(&priv->lock);
    220
    221	return IRQ_NONE;
    222
    223data_done:
    224	if (priv->flags & UNIPHIER_FI2C_STOP) {
    225stop:
    226		uniphier_fi2c_stop(priv);
    227	} else {
    228complete:
    229		priv->enabled_irqs = 0;
    230		uniphier_fi2c_set_irqs(priv);
    231		complete(&priv->comp);
    232	}
    233
    234handled:
    235	/*
    236	 * This controller makes a pause while any bit of the IRQ status is
    237	 * asserted. Clear the asserted bit to kick the controller just before
    238	 * exiting the handler.
    239	 */
    240	uniphier_fi2c_clear_irqs(priv, irq_status);
    241
    242	spin_unlock(&priv->lock);
    243
    244	return IRQ_HANDLED;
    245}
    246
    247static void uniphier_fi2c_tx_init(struct uniphier_fi2c_priv *priv, u16 addr,
    248				  bool repeat)
    249{
    250	priv->enabled_irqs |= UNIPHIER_FI2C_INT_TE;
    251	uniphier_fi2c_set_irqs(priv);
    252
    253	/* do not use TX byte counter */
    254	writel(0, priv->membase + UNIPHIER_FI2C_TBC);
    255	/* set slave address */
    256	writel(UNIPHIER_FI2C_DTTX_CMD | addr << 1,
    257	       priv->membase + UNIPHIER_FI2C_DTTX);
    258	/*
    259	 * First chunk of data. For a repeated START condition, do not write
    260	 * data to the TX fifo here to avoid the timing issue.
    261	 */
    262	if (!repeat)
    263		uniphier_fi2c_fill_txfifo(priv, true);
    264}
    265
    266static void uniphier_fi2c_rx_init(struct uniphier_fi2c_priv *priv, u16 addr)
    267{
    268	priv->flags |= UNIPHIER_FI2C_RD;
    269
    270	if (likely(priv->len < 256)) {
    271		/*
    272		 * If possible, use RX byte counter.
    273		 * It can automatically handle NACK for the last byte.
    274		 */
    275		writel(priv->len, priv->membase + UNIPHIER_FI2C_RBC);
    276		priv->enabled_irqs |= UNIPHIER_FI2C_INT_RF |
    277				      UNIPHIER_FI2C_INT_RB;
    278	} else {
    279		/*
    280		 * The byte counter can not count over 256.  In this case,
    281		 * do not use it at all.  Drain data when FIFO gets full,
    282		 * but treat the last portion as a special case.
    283		 */
    284		writel(0, priv->membase + UNIPHIER_FI2C_RBC);
    285		priv->flags |= UNIPHIER_FI2C_MANUAL_NACK;
    286		priv->enabled_irqs |= UNIPHIER_FI2C_INT_RF;
    287	}
    288
    289	uniphier_fi2c_set_irqs(priv);
    290
    291	/* set slave address with RD bit */
    292	writel(UNIPHIER_FI2C_DTTX_CMD | UNIPHIER_FI2C_DTTX_RD | addr << 1,
    293	       priv->membase + UNIPHIER_FI2C_DTTX);
    294}
    295
    296static void uniphier_fi2c_reset(struct uniphier_fi2c_priv *priv)
    297{
    298	writel(UNIPHIER_FI2C_RST_RST, priv->membase + UNIPHIER_FI2C_RST);
    299}
    300
    301static void uniphier_fi2c_prepare_operation(struct uniphier_fi2c_priv *priv)
    302{
    303	writel(UNIPHIER_FI2C_BRST_FOEN | UNIPHIER_FI2C_BRST_RSCL,
    304	       priv->membase + UNIPHIER_FI2C_BRST);
    305}
    306
    307static void uniphier_fi2c_recover(struct uniphier_fi2c_priv *priv)
    308{
    309	uniphier_fi2c_reset(priv);
    310	i2c_recover_bus(&priv->adap);
    311}
    312
    313static int uniphier_fi2c_master_xfer_one(struct i2c_adapter *adap,
    314					 struct i2c_msg *msg, bool repeat,
    315					 bool stop)
    316{
    317	struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);
    318	bool is_read = msg->flags & I2C_M_RD;
    319	unsigned long time_left, flags;
    320
    321	priv->len = msg->len;
    322	priv->buf = msg->buf;
    323	priv->enabled_irqs = UNIPHIER_FI2C_INT_FAULTS;
    324	priv->error = 0;
    325	priv->flags = 0;
    326
    327	if (stop)
    328		priv->flags |= UNIPHIER_FI2C_STOP;
    329
    330	reinit_completion(&priv->comp);
    331	uniphier_fi2c_clear_irqs(priv, U32_MAX);
    332	writel(UNIPHIER_FI2C_RST_TBRST | UNIPHIER_FI2C_RST_RBRST,
    333	       priv->membase + UNIPHIER_FI2C_RST);	/* reset TX/RX FIFO */
    334
    335	spin_lock_irqsave(&priv->lock, flags);
    336
    337	if (is_read)
    338		uniphier_fi2c_rx_init(priv, msg->addr);
    339	else
    340		uniphier_fi2c_tx_init(priv, msg->addr, repeat);
    341
    342	/*
    343	 * For a repeated START condition, writing a slave address to the FIFO
    344	 * kicks the controller. So, the UNIPHIER_FI2C_CR register should be
    345	 * written only for a non-repeated START condition.
    346	 */
    347	if (!repeat)
    348		writel(UNIPHIER_FI2C_CR_MST | UNIPHIER_FI2C_CR_STA,
    349		       priv->membase + UNIPHIER_FI2C_CR);
    350
    351	spin_unlock_irqrestore(&priv->lock, flags);
    352
    353	time_left = wait_for_completion_timeout(&priv->comp, adap->timeout);
    354
    355	spin_lock_irqsave(&priv->lock, flags);
    356	priv->enabled_irqs = 0;
    357	uniphier_fi2c_set_irqs(priv);
    358	spin_unlock_irqrestore(&priv->lock, flags);
    359
    360	if (!time_left) {
    361		dev_err(&adap->dev, "transaction timeout.\n");
    362		uniphier_fi2c_recover(priv);
    363		return -ETIMEDOUT;
    364	}
    365
    366	if (unlikely(priv->flags & UNIPHIER_FI2C_DEFER_STOP_COMP)) {
    367		u32 status;
    368		int ret;
    369
    370		ret = readl_poll_timeout(priv->membase + UNIPHIER_FI2C_SR,
    371					 status,
    372					 (status & UNIPHIER_FI2C_SR_STS) &&
    373					 !(status & UNIPHIER_FI2C_SR_BB),
    374					 1, 20);
    375		if (ret) {
    376			dev_err(&adap->dev,
    377				"stop condition was not completed.\n");
    378			uniphier_fi2c_recover(priv);
    379			return ret;
    380		}
    381	}
    382
    383	return priv->error;
    384}
    385
    386static int uniphier_fi2c_check_bus_busy(struct i2c_adapter *adap)
    387{
    388	struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);
    389
    390	if (readl(priv->membase + UNIPHIER_FI2C_SR) & UNIPHIER_FI2C_SR_DB) {
    391		if (priv->busy_cnt++ > 3) {
    392			/*
    393			 * If bus busy continues too long, it is probably
    394			 * in a wrong state.  Try bus recovery.
    395			 */
    396			uniphier_fi2c_recover(priv);
    397			priv->busy_cnt = 0;
    398		}
    399
    400		return -EAGAIN;
    401	}
    402
    403	priv->busy_cnt = 0;
    404	return 0;
    405}
    406
    407static int uniphier_fi2c_master_xfer(struct i2c_adapter *adap,
    408				     struct i2c_msg *msgs, int num)
    409{
    410	struct i2c_msg *msg, *emsg = msgs + num;
    411	bool repeat = false;
    412	int ret;
    413
    414	ret = uniphier_fi2c_check_bus_busy(adap);
    415	if (ret)
    416		return ret;
    417
    418	for (msg = msgs; msg < emsg; msg++) {
    419		/* Emit STOP if it is the last message or I2C_M_STOP is set. */
    420		bool stop = (msg + 1 == emsg) || (msg->flags & I2C_M_STOP);
    421
    422		ret = uniphier_fi2c_master_xfer_one(adap, msg, repeat, stop);
    423		if (ret)
    424			return ret;
    425
    426		repeat = !stop;
    427	}
    428
    429	return num;
    430}
    431
    432static u32 uniphier_fi2c_functionality(struct i2c_adapter *adap)
    433{
    434	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
    435}
    436
    437static const struct i2c_algorithm uniphier_fi2c_algo = {
    438	.master_xfer = uniphier_fi2c_master_xfer,
    439	.functionality = uniphier_fi2c_functionality,
    440};
    441
    442static int uniphier_fi2c_get_scl(struct i2c_adapter *adap)
    443{
    444	struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);
    445
    446	return !!(readl(priv->membase + UNIPHIER_FI2C_BM) &
    447							UNIPHIER_FI2C_BM_SCLS);
    448}
    449
    450static void uniphier_fi2c_set_scl(struct i2c_adapter *adap, int val)
    451{
    452	struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);
    453
    454	writel(val ? UNIPHIER_FI2C_BRST_RSCL : 0,
    455	       priv->membase + UNIPHIER_FI2C_BRST);
    456}
    457
    458static int uniphier_fi2c_get_sda(struct i2c_adapter *adap)
    459{
    460	struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);
    461
    462	return !!(readl(priv->membase + UNIPHIER_FI2C_BM) &
    463							UNIPHIER_FI2C_BM_SDAS);
    464}
    465
    466static void uniphier_fi2c_unprepare_recovery(struct i2c_adapter *adap)
    467{
    468	uniphier_fi2c_prepare_operation(i2c_get_adapdata(adap));
    469}
    470
    471static struct i2c_bus_recovery_info uniphier_fi2c_bus_recovery_info = {
    472	.recover_bus = i2c_generic_scl_recovery,
    473	.get_scl = uniphier_fi2c_get_scl,
    474	.set_scl = uniphier_fi2c_set_scl,
    475	.get_sda = uniphier_fi2c_get_sda,
    476	.unprepare_recovery = uniphier_fi2c_unprepare_recovery,
    477};
    478
    479static void uniphier_fi2c_hw_init(struct uniphier_fi2c_priv *priv)
    480{
    481	unsigned int cyc = priv->clk_cycle;
    482	u32 tmp;
    483
    484	tmp = readl(priv->membase + UNIPHIER_FI2C_CR);
    485	tmp |= UNIPHIER_FI2C_CR_MST;
    486	writel(tmp, priv->membase + UNIPHIER_FI2C_CR);
    487
    488	uniphier_fi2c_reset(priv);
    489
    490	/*
    491	 *  Standard-mode: tLOW + tHIGH = 10 us
    492	 *  Fast-mode:     tLOW + tHIGH = 2.5 us
    493	 */
    494	writel(cyc, priv->membase + UNIPHIER_FI2C_CYC);
    495	/*
    496	 *  Standard-mode: tLOW = 4.7 us, tHIGH = 4.0 us, tBUF = 4.7 us
    497	 *  Fast-mode:     tLOW = 1.3 us, tHIGH = 0.6 us, tBUF = 1.3 us
    498	 * "tLow/tHIGH = 5/4" meets both.
    499	 */
    500	writel(cyc * 5 / 9, priv->membase + UNIPHIER_FI2C_LCTL);
    501	/*
    502	 *  Standard-mode: tHD;STA = 4.0 us, tSU;STA = 4.7 us, tSU;STO = 4.0 us
    503	 *  Fast-mode:     tHD;STA = 0.6 us, tSU;STA = 0.6 us, tSU;STO = 0.6 us
    504	 */
    505	writel(cyc / 2, priv->membase + UNIPHIER_FI2C_SSUT);
    506	/*
    507	 *  Standard-mode: tSU;DAT = 250 ns
    508	 *  Fast-mode:     tSU;DAT = 100 ns
    509	 */
    510	writel(cyc / 16, priv->membase + UNIPHIER_FI2C_DSUT);
    511
    512	uniphier_fi2c_prepare_operation(priv);
    513}
    514
    515static int uniphier_fi2c_probe(struct platform_device *pdev)
    516{
    517	struct device *dev = &pdev->dev;
    518	struct uniphier_fi2c_priv *priv;
    519	u32 bus_speed;
    520	unsigned long clk_rate;
    521	int irq, ret;
    522
    523	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
    524	if (!priv)
    525		return -ENOMEM;
    526
    527	priv->membase = devm_platform_ioremap_resource(pdev, 0);
    528	if (IS_ERR(priv->membase))
    529		return PTR_ERR(priv->membase);
    530
    531	irq = platform_get_irq(pdev, 0);
    532	if (irq < 0)
    533		return irq;
    534
    535	if (of_property_read_u32(dev->of_node, "clock-frequency", &bus_speed))
    536		bus_speed = I2C_MAX_STANDARD_MODE_FREQ;
    537
    538	if (!bus_speed || bus_speed > I2C_MAX_FAST_MODE_FREQ) {
    539		dev_err(dev, "invalid clock-frequency %d\n", bus_speed);
    540		return -EINVAL;
    541	}
    542
    543	priv->clk = devm_clk_get(dev, NULL);
    544	if (IS_ERR(priv->clk)) {
    545		dev_err(dev, "failed to get clock\n");
    546		return PTR_ERR(priv->clk);
    547	}
    548
    549	ret = clk_prepare_enable(priv->clk);
    550	if (ret)
    551		return ret;
    552
    553	clk_rate = clk_get_rate(priv->clk);
    554	if (!clk_rate) {
    555		dev_err(dev, "input clock rate should not be zero\n");
    556		ret = -EINVAL;
    557		goto disable_clk;
    558	}
    559
    560	priv->clk_cycle = clk_rate / bus_speed;
    561	init_completion(&priv->comp);
    562	spin_lock_init(&priv->lock);
    563	priv->adap.owner = THIS_MODULE;
    564	priv->adap.algo = &uniphier_fi2c_algo;
    565	priv->adap.dev.parent = dev;
    566	priv->adap.dev.of_node = dev->of_node;
    567	strlcpy(priv->adap.name, "UniPhier FI2C", sizeof(priv->adap.name));
    568	priv->adap.bus_recovery_info = &uniphier_fi2c_bus_recovery_info;
    569	i2c_set_adapdata(&priv->adap, priv);
    570	platform_set_drvdata(pdev, priv);
    571
    572	uniphier_fi2c_hw_init(priv);
    573
    574	ret = devm_request_irq(dev, irq, uniphier_fi2c_interrupt, 0,
    575			       pdev->name, priv);
    576	if (ret) {
    577		dev_err(dev, "failed to request irq %d\n", irq);
    578		goto disable_clk;
    579	}
    580
    581	ret = i2c_add_adapter(&priv->adap);
    582disable_clk:
    583	if (ret)
    584		clk_disable_unprepare(priv->clk);
    585
    586	return ret;
    587}
    588
    589static int uniphier_fi2c_remove(struct platform_device *pdev)
    590{
    591	struct uniphier_fi2c_priv *priv = platform_get_drvdata(pdev);
    592
    593	i2c_del_adapter(&priv->adap);
    594	clk_disable_unprepare(priv->clk);
    595
    596	return 0;
    597}
    598
    599static int __maybe_unused uniphier_fi2c_suspend(struct device *dev)
    600{
    601	struct uniphier_fi2c_priv *priv = dev_get_drvdata(dev);
    602
    603	clk_disable_unprepare(priv->clk);
    604
    605	return 0;
    606}
    607
    608static int __maybe_unused uniphier_fi2c_resume(struct device *dev)
    609{
    610	struct uniphier_fi2c_priv *priv = dev_get_drvdata(dev);
    611	int ret;
    612
    613	ret = clk_prepare_enable(priv->clk);
    614	if (ret)
    615		return ret;
    616
    617	uniphier_fi2c_hw_init(priv);
    618
    619	return 0;
    620}
    621
    622static const struct dev_pm_ops uniphier_fi2c_pm_ops = {
    623	SET_SYSTEM_SLEEP_PM_OPS(uniphier_fi2c_suspend, uniphier_fi2c_resume)
    624};
    625
    626static const struct of_device_id uniphier_fi2c_match[] = {
    627	{ .compatible = "socionext,uniphier-fi2c" },
    628	{ /* sentinel */ }
    629};
    630MODULE_DEVICE_TABLE(of, uniphier_fi2c_match);
    631
    632static struct platform_driver uniphier_fi2c_drv = {
    633	.probe  = uniphier_fi2c_probe,
    634	.remove = uniphier_fi2c_remove,
    635	.driver = {
    636		.name  = "uniphier-fi2c",
    637		.of_match_table = uniphier_fi2c_match,
    638		.pm = &uniphier_fi2c_pm_ops,
    639	},
    640};
    641module_platform_driver(uniphier_fi2c_drv);
    642
    643MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
    644MODULE_DESCRIPTION("UniPhier FIFO-builtin I2C bus driver");
    645MODULE_LICENSE("GPL");