[PATCH v3 2/4] tpm: tpm_tis_spi: Export functionality to other drivers

[Stephen Boyd]

We want to use most of the code in this driver, except we want to modify
the flow control and idle behavior. Let's "libify" this driver so that
another driver can call the code in here and slightly tweak the
behavior.

Cc: Andrey Pronin <apronin@xxxxxxxxxxxx>
Cc: Duncan Laurie <dlaurie@xxxxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Guenter Roeck <groeck@xxxxxxxxxxxx>
Cc: Alexander Steffen <Alexander.Steffen@xxxxxxxxxxxx>
Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
---
 drivers/char/tpm/tpm_tis_spi.c | 98 +++++++++++++++++++---------------
 drivers/char/tpm/tpm_tis_spi.h | 37 +++++++++++++
 2 files changed, 93 insertions(+), 42 deletions(-)
 create mode 100644 drivers/char/tpm/tpm_tis_spi.h

diff --git a/drivers/char/tpm/tpm_tis_spi.c b/drivers/char/tpm/tpm_tis_spi.c
index 19513e622053..fd3fb4f9f506 100644
--- a/drivers/char/tpm/tpm_tis_spi.c
+++ b/drivers/char/tpm/tpm_tis_spi.c
@@ -36,26 +36,43 @@
 #include <linux/tpm.h>
 #include "tpm.h"
 #include "tpm_tis_core.h"
+#include "tpm_tis_spi.h"
 
 #define MAX_SPI_FRAMESIZE 64
 
-struct tpm_tis_spi_phy {
-	struct tpm_tis_data priv;
-	struct spi_device *spi_device;
-	u8 *iobuf;
-};
-
-static inline struct tpm_tis_spi_phy *to_tpm_tis_spi_phy(struct tpm_tis_data *data)
+static int tpm_tis_spi_flow_control(struct tpm_tis_spi_phy *phy,
+				    struct spi_transfer *spi_xfer)
 {
-	return container_of(data, struct tpm_tis_spi_phy, priv);
+	struct spi_message m;
+	int ret, i;
+
+	if ((phy->iobuf[3] & 0x01) == 0) {
+		// handle SPI wait states
+		phy->iobuf[0] = 0;
+
+		for (i = 0; i < TPM_RETRY; i++) {
+			spi_xfer->len = 1;
+			spi_message_init(&m);
+			spi_message_add_tail(spi_xfer, &m);
+			ret = spi_sync_locked(phy->spi_device, &m);
+			if (ret < 0)
+				return ret;
+			if (phy->iobuf[0] & 0x01)
+				break;
+		}
+
+		if (i == TPM_RETRY)
+			return -ETIMEDOUT;
+	}
+
+	return 0;
 }
 
-static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
+int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
 				u8 *in, const u8 *out)
 {
 	struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
 	int ret = 0;
-	int i;
 	struct spi_message m;
 	struct spi_transfer spi_xfer;
 	u8 transfer_len;
@@ -82,26 +99,9 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
 		if (ret < 0)
 			goto exit;
 
-		if ((phy->iobuf[3] & 0x01) == 0) {
-			// handle SPI wait states
-			phy->iobuf[0] = 0;
-
-			for (i = 0; i < TPM_RETRY; i++) {
-				spi_xfer.len = 1;
-				spi_message_init(&m);
-				spi_message_add_tail(&spi_xfer, &m);
-				ret = spi_sync_locked(phy->spi_device, &m);
-				if (ret < 0)
-					goto exit;
-				if (phy->iobuf[0] & 0x01)
-					break;
-			}
-
-			if (i == TPM_RETRY) {
-				ret = -ETIMEDOUT;
-				goto exit;
-			}
-		}
+		ret = phy->flow_control(phy, &spi_xfer);
+		if (ret < 0)
+			goto exit;
 
 		spi_xfer.cs_change = 0;
 		spi_xfer.len = transfer_len;
@@ -117,6 +117,8 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
 
 		spi_message_init(&m);
 		spi_message_add_tail(&spi_xfer, &m);
+		if (phy->pre_transfer)
+			phy->pre_transfer(phy);
 		ret = spi_sync_locked(phy->spi_device, &m);
 		if (ret < 0)
 			goto exit;
@@ -133,9 +135,10 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
 	spi_bus_unlock(phy->spi_device->master);
 	return ret;
 }
+EXPORT_SYMBOL_GPL(tpm_tis_spi_transfer);
 
-static int tpm_tis_spi_read_bytes(struct tpm_tis_data *data, u32 addr,
-				  u16 len, u8 *result)
+static int tpm_tis_spi_read_bytes(struct tpm_tis_data *data, u32 addr, u16 len,
+				  u8 *result)
 {
 	return tpm_tis_spi_transfer(data, addr, len, result, NULL);
 }
@@ -146,7 +149,7 @@ static int tpm_tis_spi_write_bytes(struct tpm_tis_data *data, u32 addr,
 	return tpm_tis_spi_transfer(data, addr, len, NULL, value);
 }
 
-static int tpm_tis_spi_read16(struct tpm_tis_data *data, u32 addr, u16 *result)
+int tpm_tis_spi_read16(struct tpm_tis_data *data, u32 addr, u16 *result)
 {
 	__le16 result_le;
 	int rc;
@@ -158,8 +161,9 @@ static int tpm_tis_spi_read16(struct tpm_tis_data *data, u32 addr, u16 *result)
 
 	return rc;
 }
+EXPORT_SYMBOL_GPL(tpm_tis_spi_read16);
 
-static int tpm_tis_spi_read32(struct tpm_tis_data *data, u32 addr, u32 *result)
+int tpm_tis_spi_read32(struct tpm_tis_data *data, u32 addr, u32 *result)
 {
 	__le32 result_le;
 	int rc;
@@ -171,8 +175,9 @@ static int tpm_tis_spi_read32(struct tpm_tis_data *data, u32 addr, u32 *result)
 
 	return rc;
 }
+EXPORT_SYMBOL_GPL(tpm_tis_spi_read32);
 
-static int tpm_tis_spi_write32(struct tpm_tis_data *data, u32 addr, u32 value)
+int tpm_tis_spi_write32(struct tpm_tis_data *data, u32 addr, u32 value)
 {
 	__le32 value_le;
 	int rc;
@@ -183,6 +188,20 @@ static int tpm_tis_spi_write32(struct tpm_tis_data *data, u32 addr, u32 value)
 
 	return rc;
 }
+EXPORT_SYMBOL_GPL(tpm_tis_spi_write32);
+
+int tpm_tis_spi_init(struct spi_device *spi, struct tpm_tis_spi_phy *phy,
+		     int irq, const struct tpm_tis_phy_ops *phy_ops)
+{
+	phy->iobuf = devm_kmalloc(&spi->dev, MAX_SPI_FRAMESIZE, GFP_KERNEL);
+	if (!phy->iobuf)
+		return -ENOMEM;
+
+	phy->spi_device = spi;
+
+	return tpm_tis_core_init(&spi->dev, &phy->priv, irq, phy_ops, NULL);
+}
+EXPORT_SYMBOL_GPL(tpm_tis_spi_init);
 
 static const struct tpm_tis_phy_ops tpm_spi_phy_ops = {
 	.read_bytes = tpm_tis_spi_read_bytes,
@@ -202,11 +221,7 @@ static int tpm_tis_spi_probe(struct spi_device *dev)
 	if (!phy)
 		return -ENOMEM;
 
-	phy->spi_device = dev;
-
-	phy->iobuf = devm_kmalloc(&dev->dev, MAX_SPI_FRAMESIZE, GFP_KERNEL);
-	if (!phy->iobuf)
-		return -ENOMEM;
+	phy->flow_control = tpm_tis_spi_flow_control;
 
 	/* If the SPI device has an IRQ then use that */
 	if (dev->irq > 0)
@@ -214,8 +229,7 @@ static int tpm_tis_spi_probe(struct spi_device *dev)
 	else
 		irq = -1;
 
-	return tpm_tis_core_init(&dev->dev, &phy->priv, irq, &tpm_spi_phy_ops,
-				 NULL);
+	return tpm_tis_spi_init(dev, phy, irq, &tpm_spi_phy_ops);
 }
 
 static SIMPLE_DEV_PM_OPS(tpm_tis_pm, tpm_pm_suspend, tpm_tis_resume);
diff --git a/drivers/char/tpm/tpm_tis_spi.h b/drivers/char/tpm/tpm_tis_spi.h
new file mode 100644
index 000000000000..48be5130794a
--- /dev/null
+++ b/drivers/char/tpm/tpm_tis_spi.h
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2015 Infineon Technologies AG
+ * Copyright (C) 2016 STMicroelectronics SAS
+ */
+
+#ifndef TPM_TIS_SPI_H
+#define TPM_TIS_SPI_H
+
+#include "tpm_tis_core.h"
+
+struct tpm_tis_spi_phy {
+	struct tpm_tis_data priv;
+	struct spi_device *spi_device;
+	int (*flow_control)(struct tpm_tis_spi_phy *phy,
+			     struct spi_transfer *xfer);
+	void (*pre_transfer)(struct tpm_tis_spi_phy *phy);
+
+	u8 *iobuf;
+};
+
+static inline struct tpm_tis_spi_phy *to_tpm_tis_spi_phy(struct tpm_tis_data *data)
+{
+	return container_of(data, struct tpm_tis_spi_phy, priv);
+}
+
+extern int tpm_tis_spi_init(struct spi_device *spi, struct tpm_tis_spi_phy *phy,
+			    int irq, const struct tpm_tis_phy_ops *phy_ops);
+
+extern int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
+				u8 *in, const u8 *out);
+
+extern int tpm_tis_spi_read16(struct tpm_tis_data *data, u32 addr, u16 *result);
+extern int tpm_tis_spi_read32(struct tpm_tis_data *data, u32 addr, u32 *result);
+extern int tpm_tis_spi_write32(struct tpm_tis_data *data, u32 addr, u32 value);
+
+#endif
-- 
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