diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 8bc6fb8..a8f48a2 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -149,6 +149,7 @@ struct tpm_chip {
 	 * when the driver is unregistered, see tpm_try_get_ops.
 	 */
 	struct rw_semaphore ops_sem;
+	const struct tpm_class_lowlevel *lowlevel;
 	const struct tpm_class_ops *ops;
 
 	unsigned int flags;
@@ -466,6 +467,46 @@ static inline void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value)
 	tpm_buf_append(buf, (u8 *) &value2, 4);
 }
 
+static inline void tpm_read_bytes(struct tpm_chip *chip, u32 addr, u16 len,
+				  u8 *result)
+{
+	chip->lowlevel->read_bytes(chip, addr, len, result);
+}
+
+static inline u8 tpm_read8(struct tpm_chip *chip, u32 addr)
+{
+	u8 result;
+
+	chip->lowlevel->read_bytes(chip, addr, 1, &result);
+	return result;
+}
+
+static inline u16 tpm_read16(struct tpm_chip *chip, u32 addr)
+{
+	return chip->lowlevel->read16(chip, addr);
+}
+
+static inline u32 tpm_read32(struct tpm_chip *chip, u32 addr)
+{
+	return chip->lowlevel->read32(chip, addr);
+}
+
+static inline void tpm_write_bytes(struct tpm_chip *chip, u32 addr, u16 len,
+				   u8 *value)
+{
+	chip->lowlevel->write_bytes(chip, addr, len, value);
+}
+
+static inline void tpm_write8(struct tpm_chip *chip, u32 addr, u8 value)
+{
+	chip->lowlevel->write_bytes(chip, addr, 1, &value);
+}
+
+static inline void tpm_write32(struct tpm_chip *chip, u32 addr, u32 value)
+{
+	chip->lowlevel->write32(chip, addr, value);
+}
+
 extern struct class *tpm_class;
 extern dev_t tpm_devt;
 extern const struct file_operations tpm_fops;
diff --git a/drivers/char/tpm/tpm_tis.c b/drivers/char/tpm/tpm_tis.c
index 1e45e73..eb0b6802 100644
--- a/drivers/char/tpm/tpm_tis.c
+++ b/drivers/char/tpm/tpm_tis.c
@@ -132,10 +132,9 @@ static inline int is_itpm(struct acpi_device *dev)
  * correct values in the other bits.' */
 static int wait_startup(struct tpm_chip *chip, int l)
 {
-	struct priv_data *priv = dev_get_drvdata(&chip->dev);
 	unsigned long stop = jiffies + chip->timeout_a;
 	do {
-		if (ioread8(priv->iobase + TPM_ACCESS(l)) &
+		if (tpm_read8(chip, TPM_ACCESS(l)) &
 		    TPM_ACCESS_VALID)
 			return 0;
 		msleep(TPM_TIMEOUT);
@@ -147,7 +146,7 @@ static int check_locality(struct tpm_chip *chip, int l)
 {
 	struct priv_data *priv = dev_get_drvdata(&chip->dev);
 
-	if ((ioread8(priv->iobase + TPM_ACCESS(l)) &
+	if ((tpm_read8(chip, TPM_ACCESS(l)) &
 	     (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID)) ==
 	    (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID))
 		return priv->locality = l;
@@ -157,13 +156,11 @@ static int check_locality(struct tpm_chip *chip, int l)
 
 static void release_locality(struct tpm_chip *chip, int l, int force)
 {
-	struct priv_data *priv = dev_get_drvdata(&chip->dev);
-
-	if (force || (ioread8(priv->iobase + TPM_ACCESS(l)) &
+	if (force || (tpm_read8(chip, TPM_ACCESS(l)) &
 		      (TPM_ACCESS_REQUEST_PENDING | TPM_ACCESS_VALID)) ==
 	    (TPM_ACCESS_REQUEST_PENDING | TPM_ACCESS_VALID))
-		iowrite8(TPM_ACCESS_ACTIVE_LOCALITY,
-			 priv->iobase + TPM_ACCESS(l));
+		tpm_write8(chip, TPM_ACCESS(l), TPM_ACCESS_ACTIVE_LOCALITY);
+
 }
 
 static int request_locality(struct tpm_chip *chip, int l)
@@ -175,8 +172,8 @@ static int request_locality(struct tpm_chip *chip, int l)
 	if (check_locality(chip, l) >= 0)
 		return l;
 
-	iowrite8(TPM_ACCESS_REQUEST_USE,
-		 priv->iobase + TPM_ACCESS(l));
+	tpm_write8(chip, TPM_ACCESS(l), TPM_ACCESS_REQUEST_USE);
+
 
 	stop = jiffies + chip->timeout_a;
 
@@ -211,8 +208,7 @@ static u8 tpm_tis_status(struct tpm_chip *chip)
 {
 	struct priv_data *priv = dev_get_drvdata(&chip->dev);
 
-	return ioread8(priv->iobase +
-		       TPM_STS(priv->locality));
+	return tpm_read8(chip, TPM_STS(priv->locality));
 }
 
 static void tpm_tis_ready(struct tpm_chip *chip)
@@ -220,8 +216,7 @@ static void tpm_tis_ready(struct tpm_chip *chip)
 	struct priv_data *priv = dev_get_drvdata(&chip->dev);
 
 	/* this causes the current command to be aborted */
-	iowrite8(TPM_STS_COMMAND_READY,
-		 priv->iobase + TPM_STS(priv->locality));
+	tpm_write8(chip, TPM_STS(priv->locality), TPM_STS_COMMAND_READY);
 }
 
 static int get_burstcount(struct tpm_chip *chip)
@@ -234,11 +229,8 @@ static int get_burstcount(struct tpm_chip *chip)
 	/* which timeout value, spec has 2 answers (c & d) */
 	stop = jiffies + chip->timeout_d;
 	do {
-		burstcnt = ioread8(priv->iobase +
-				   TPM_STS(priv->locality) + 1);
-		burstcnt += ioread8(priv->iobase +
-				    TPM_STS(priv->locality) +
-				    2) << 8;
+		burstcnt = tpm_read8(chip, TPM_STS(priv->locality) + 1);
+		burstcnt += tpm_read8(chip, TPM_STS(priv->locality) + 2) << 8;
 		if (burstcnt)
 			return burstcnt;
 		msleep(TPM_TIMEOUT);
@@ -254,12 +246,11 @@ static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
 	       wait_for_tpm_stat(chip,
 				 TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 				 chip->timeout_c,
-				 &priv->read_queue, true)
-	       == 0) {
-		burstcnt = get_burstcount(chip);
-		for (; burstcnt > 0 && size < count; burstcnt--)
-			buf[size++] = ioread8(priv->iobase +
-					      TPM_DATA_FIFO(priv->locality));
+				 &priv->read_queue, true) == 0) {
+		burstcnt = min_t(int, get_burstcount(chip), count - size);
+		tpm_read_bytes(chip, TPM_DATA_FIFO(priv->locality), burstcnt,
+			       buf + size);
+		size += burstcnt;
 	}
 	return size;
 }
@@ -341,12 +332,10 @@ static int tpm_tis_send_data(struct tpm_chip *chip, u8 *buf, size_t len)
 	}
 
 	while (count < len - 1) {
-		burstcnt = get_burstcount(chip);
-		for (; burstcnt > 0 && count < len - 1; burstcnt--) {
-			iowrite8(buf[count], priv->iobase +
-				 TPM_DATA_FIFO(priv->locality));
-			count++;
-		}
+		burstcnt = min_t(int, get_burstcount(chip), len - count - 1);
+		tpm_write_bytes(chip, TPM_DATA_FIFO(priv->locality),
+				burstcnt, buf + count);
+		count += burstcnt;
 
 		wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
 				  &priv->int_queue, false);
@@ -358,8 +347,7 @@ static int tpm_tis_send_data(struct tpm_chip *chip, u8 *buf, size_t len)
 	}
 
 	/* write last byte */
-	iowrite8(buf[count],
-		 priv->iobase + TPM_DATA_FIFO(priv->locality));
+	tpm_write8(chip, TPM_DATA_FIFO(priv->locality), buf[count]);
 	wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
 			  &priv->int_queue, false);
 	status = tpm_tis_status(chip);
@@ -381,12 +369,10 @@ static void disable_interrupts(struct tpm_chip *chip)
 	struct priv_data *priv = dev_get_drvdata(&chip->dev);
 	u32 intmask;
 
-	intmask =
-	    ioread32(priv->iobase +
-		     TPM_INT_ENABLE(priv->locality));
+	intmask = tpm_read32(chip, TPM_INT_ENABLE(priv->locality));
 	intmask &= ~TPM_GLOBAL_INT_ENABLE;
-	iowrite32(intmask,
-		  priv->iobase + TPM_INT_ENABLE(priv->locality));
+	tpm_write32(chip, TPM_INT_ENABLE(priv->locality), intmask);
+
 	devm_free_irq(&chip->dev, priv->irq, chip);
 	priv->irq = 0;
 	chip->flags &= ~TPM_CHIP_FLAG_IRQ;
@@ -409,9 +395,7 @@ static int tpm_tis_send_main(struct tpm_chip *chip, u8 *buf, size_t len)
 		return rc;
 
 	/* go and do it */
-	iowrite8(TPM_STS_GO,
-		 priv->iobase + TPM_STS(priv->locality));
-
+	tpm_write8(chip, TPM_STS(priv->locality), TPM_STS_GO);
 	if (chip->flags & TPM_CHIP_FLAG_IRQ) {
 		ordinal = be32_to_cpu(*((__be32 *) (buf + 6)));
 
@@ -471,11 +455,10 @@ static const struct tis_vendor_timeout_override vendor_timeout_overrides[] = {
 static bool tpm_tis_update_timeouts(struct tpm_chip *chip,
 				    unsigned long *timeout_cap)
 {
-	struct priv_data *priv = dev_get_drvdata(&chip->dev);
 	int i;
 	u32 did_vid;
 
-	did_vid = ioread32(priv->iobase + TPM_DID_VID(0));
+	did_vid = tpm_read32(chip, TPM_DID_VID(0));
 
 	for (i = 0; i != ARRAY_SIZE(vendor_timeout_overrides); i++) {
 		if (vendor_timeout_overrides[i].did_vid != did_vid)
@@ -503,7 +486,7 @@ static int probe_itpm(struct tpm_chip *chip)
 	};
 	size_t len = sizeof(cmd_getticks);
 	bool rem_itpm = itpm;
-	u16 vendor = ioread16(priv->iobase + TPM_DID_VID(0));
+	u16 vendor = tpm_read16(chip, TPM_DID_VID(0));
 
 	/* probe only iTPMS */
 	if (vendor != TPM_VID_INTEL)
@@ -561,6 +544,61 @@ static const struct tpm_class_ops tpm_tis = {
 	.req_canceled = tpm_tis_req_canceled,
 };
 
+static void tpm_mem_read_bytes(struct tpm_chip *chip, u32 addr, u16 len,
+			       u8 *result)
+{
+	struct priv_data *priv = dev_get_drvdata(&chip->dev);
+
+	while (len--)
+		*result++ = ioread8(priv->iobase + addr);
+}
+
+static void tpm_mem_write_bytes(struct tpm_chip *chip, u32 addr, u16 len,
+				u8 *value)
+{
+	struct priv_data *priv = dev_get_drvdata(&chip->dev);
+
+	while (len--)
+		iowrite8(*value++, priv->iobase + addr);
+}
+
+static u16 tpm_mem_read16(struct tpm_chip *chip, u32 addr)
+{
+	struct priv_data *priv = dev_get_drvdata(&chip->dev);
+
+	return ioread16(priv->iobase + addr);
+}
+
+static void tpm_mem_write16(struct tpm_chip *chip, u32 addr, u16 value)
+{
+	struct priv_data *priv = dev_get_drvdata(&chip->dev);
+
+	iowrite16(value, priv->iobase + addr);
+}
+
+static u32 tpm_mem_read32(struct tpm_chip *chip, u32 addr)
+{
+	struct priv_data *priv = dev_get_drvdata(&chip->dev);
+
+	return ioread32(priv->iobase + addr);
+}
+
+static void tpm_mem_write32(struct tpm_chip *chip, u32 addr, u32 value)
+{
+	struct priv_data *priv = dev_get_drvdata(&chip->dev);
+
+	iowrite32(value, priv->iobase + addr);
+}
+
+static const struct tpm_class_lowlevel tpm_mem = {
+	.read_bytes = tpm_mem_read_bytes,
+	.write_bytes = tpm_mem_write_bytes,
+	.read16 = tpm_mem_read16,
+	.write16 = tpm_mem_write16,
+	.read32 = tpm_mem_read32,
+	.write32 = tpm_mem_write32,
+};
+
 static irqreturn_t tis_int_handler(int dummy, void *dev_id)
 {
 	struct tpm_chip *chip = dev_id;
@@ -568,8 +606,7 @@ static irqreturn_t tis_int_handler(int dummy, void *dev_id)
 	u32 interrupt;
 	int i;
 
-	interrupt = ioread32(priv->iobase +
-			     TPM_INT_STATUS(priv->locality));
+	interrupt = tpm_read32(chip, TPM_INT_STATUS(priv->locality));
 
 	if (interrupt == 0)
 		return IRQ_NONE;
@@ -587,10 +624,9 @@ static irqreturn_t tis_int_handler(int dummy, void *dev_id)
 		wake_up_interruptible(&priv->int_queue);
 
 	/* Clear interrupts handled with TPM_EOI */
-	iowrite32(interrupt,
-		  priv->iobase +
-		  TPM_INT_STATUS(priv->locality));
-	ioread32(priv->iobase + TPM_INT_STATUS(priv->locality));
+	tpm_write32(chip, TPM_INT_STATUS(priv->locality), interrupt);
+
+	tpm_read32(chip, TPM_INT_STATUS(priv->locality));
 	return IRQ_HANDLED;
 }
 
@@ -612,19 +648,16 @@ static int tpm_tis_probe_irq_single(struct tpm_chip *chip, u32 intmask,
 	}
 	priv->irq = irq;
 
-	original_int_vec = ioread8(priv->iobase +
-				   TPM_INT_VECTOR(priv->locality));
-	iowrite8(irq,
-		 priv->iobase + TPM_INT_VECTOR(priv->locality));
+	original_int_vec = tpm_read8(chip, TPM_INT_VECTOR(priv->locality));
+	tpm_write8(chip, TPM_INT_VECTOR(priv->locality), irq);
 
 	/* Clear all existing */
-	iowrite32(ioread32(priv->iobase +
-			   TPM_INT_STATUS(priv->locality)),
-		  priv->iobase + TPM_INT_STATUS(priv->locality));
+	tpm_write32(chip, TPM_INT_STATUS(priv->locality),
+		    tpm_read32(chip, TPM_INT_STATUS(priv->locality)));
 
 	/* Turn on */
-	iowrite32(intmask | TPM_GLOBAL_INT_ENABLE,
-		  priv->iobase + TPM_INT_ENABLE(priv->locality));
+	tpm_write32(chip, TPM_INT_ENABLE(priv->locality),
+		    intmask | TPM_GLOBAL_INT_ENABLE);
 
 	priv->irq_tested = false;
 
@@ -640,8 +673,9 @@ static int tpm_tis_probe_irq_single(struct tpm_chip *chip, u32 intmask,
 	 * will call disable_irq which undoes all of the above.
 	 */
 	if (!(chip->flags & TPM_CHIP_FLAG_IRQ)) {
-		iowrite8(original_int_vec,
-			 priv->iobase + TPM_INT_VECTOR(priv->locality));
+		tpm_write8(chip, TPM_INT_VECTOR(priv->locality),
+			   original_int_vec);
+
 		return 1;
 	}
 
@@ -658,8 +692,7 @@ static void tpm_tis_probe_irq(struct tpm_chip *chip, u32 intmask)
 	u8 original_int_vec;
 	int i;
 
-	original_int_vec = ioread8(priv->iobase +
-				   TPM_INT_VECTOR(priv->locality));
+	original_int_vec = tpm_read8(chip, TPM_INT_VECTOR(priv->locality));
 
 	if (!original_int_vec) {
 		if (IS_ENABLED(CONFIG_X86))
@@ -679,12 +712,12 @@ MODULE_PARM_DESC(interrupts, "Enable interrupts");
 static void tpm_tis_remove(struct tpm_chip *chip)
 {
 	struct priv_data *priv = dev_get_drvdata(&chip->dev);
-	void __iomem *reg = priv->iobase + TPM_INT_ENABLE(priv->locality);
+	u32 reg = TPM_INT_ENABLE(priv->locality);
 
 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
 		tpm2_shutdown(chip, TPM2_SU_CLEAR);
 
-	iowrite32(~TPM_GLOBAL_INT_ENABLE & ioread32(reg), reg);
+	tpm_write32(chip, reg, ~TPM_GLOBAL_INT_ENABLE & tpm_read32(chip, reg));
 	release_locality(chip, priv->locality, 1);
 }
 
@@ -712,6 +745,8 @@ static int tpm_tis_init(struct device *dev, struct tpm_info *tpm_info,
 	if (IS_ERR(priv->iobase))
 		return PTR_ERR(priv->iobase);
 
+	chip->lowlevel = &tpm_mem;
+
 	/* Maximum timeouts */
 	chip->timeout_a = TIS_TIMEOUT_A_MAX;
 	chip->timeout_b = TIS_TIMEOUT_B_MAX;
@@ -726,13 +761,11 @@ static int tpm_tis_init(struct device *dev, struct tpm_info *tpm_info,
 	}
 
 	/* Take control of the TPM's interrupt hardware and shut it off */
-	intmask = ioread32(priv->iobase +
-			   TPM_INT_ENABLE(priv->locality));
+	intmask = tpm_read32(chip, TPM_INT_ENABLE(priv->locality));
 	intmask |= TPM_INTF_CMD_READY_INT | TPM_INTF_LOCALITY_CHANGE_INT |
 		   TPM_INTF_DATA_AVAIL_INT | TPM_INTF_STS_VALID_INT;
 	intmask &= ~TPM_GLOBAL_INT_ENABLE;
-	iowrite32(intmask,
-		  priv->iobase + TPM_INT_ENABLE(priv->locality));
+	tpm_write32(chip, TPM_INT_ENABLE(priv->locality), intmask);
 
 	if (request_locality(chip, 0) != 0) {
 		rc = -ENODEV;
@@ -743,12 +776,12 @@ static int tpm_tis_init(struct device *dev, struct tpm_info *tpm_info,
 	if (rc)
 		goto out_err;
 
-	vendor = ioread32(priv->iobase + TPM_DID_VID(0));
+	vendor = tpm_read32(chip, TPM_DID_VID(0));
 	priv->manufacturer_id = vendor;
 
 	dev_info(dev, "%s TPM (device-id 0x%X, rev-id %d)\n",
 		 (chip->flags & TPM_CHIP_FLAG_TPM2) ? "2.0" : "1.2",
-		 vendor >> 16, ioread8(priv->iobase + TPM_RID(0)));
+		 vendor >> 16, tpm_read8(chip, TPM_RID(0)));
 
 	if (!itpm) {
 		probe = probe_itpm(chip);
@@ -764,9 +797,7 @@ static int tpm_tis_init(struct device *dev, struct tpm_info *tpm_info,
 
 
 	/* Figure out the capabilities */
-	intfcaps =
-	    ioread32(priv->iobase +
-		     TPM_INTF_CAPS(priv->locality));
+	intfcaps = tpm_read32(chip, TPM_INTF_CAPS(priv->locality));
 	dev_dbg(dev, "TPM interface capabilities (0x%x):\n",
 		intfcaps);
 	if (intfcaps & TPM_INTF_BURST_COUNT_STATIC)
@@ -849,18 +880,15 @@ static void tpm_tis_reenable_interrupts(struct tpm_chip *chip)
 
 	/* reenable interrupts that device may have lost or
 	   BIOS/firmware may have disabled */
-	iowrite8(priv->irq, priv->iobase +
-		 TPM_INT_VECTOR(priv->locality));
+	tpm_write8(chip, TPM_INT_VECTOR(priv->locality), priv->irq);
 
-	intmask =
-	    ioread32(priv->iobase + TPM_INT_ENABLE(priv->locality));
+	intmask = tpm_read32(chip, TPM_INT_ENABLE(priv->locality));
 
 	intmask |= TPM_INTF_CMD_READY_INT
 	    | TPM_INTF_LOCALITY_CHANGE_INT | TPM_INTF_DATA_AVAIL_INT
 	    | TPM_INTF_STS_VALID_INT | TPM_GLOBAL_INT_ENABLE;
 
-	iowrite32(intmask,
-		  priv->iobase + TPM_INT_ENABLE(priv->locality));
+	tpm_write32(chip, TPM_INT_ENABLE(priv->locality), intmask);
 }
 
 static int tpm_tis_resume(struct device *dev)
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 706e63e..19d5d426 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -46,6 +46,17 @@ struct tpm_class_ops {
 
 };
 
+struct tpm_class_lowlevel {
+	void (*read_bytes)(struct tpm_chip *chip, u32 addr, u16 len,
+			   u8 *result);
+	void (*write_bytes)(struct tpm_chip *chip, u32 addr, u16 len,
+			    u8 *value);
+	u16 (*read16)(struct tpm_chip *chip, u32 addr);
+	void (*write16)(struct tpm_chip *chip, u32 addr, u16 src);
+	u32 (*read32)(struct tpm_chip *chip, u32 addr);
+	void (*write32)(struct tpm_chip *chip, u32 addr, u32 src);
+};
+
 #if defined(CONFIG_TCG_TPM) || defined(CONFIG_TCG_TPM_MODULE)
 
 extern int tpm_is_tpm2(u32 chip_num);
