tpm/tpm_tis_spi: Add support for spi phy

Spi protocol standardized by the TCG is now supported by most of TPM
vendors.

It supports SPI Bit Protocol as describe in the TCG PTP
specification (chapter 6.4.6 SPI Bit Protocol).

Irq mode is not supported.

This commit is based on the initial work by Peter Huewe.

Signed-off-by: Peter Huewe <[e-mail]>
Signed-off-by: Alexander Steffen <[e-mail]>
Signed-off-by: Christophe Ricard <[e-mail]>
Reviewed-by: Jarkko Sakkinen <[e-mail]>
Tested-by: Jarkko Sakkinen <[e-mail]>
Tested-by: Stefan Berger <[e-mail]>
Reviewed-by: Stefan Berger <[e-mail]>
Signed-off-by: Jarkko Sakkinen <[e-mail]>

Documentation/devicetree/bindings/security/tpm/tpm_tis_spi.txt

···
+Required properties:
+- compatible: should be one of the following
+    "st,st33htpm-spi"
+    "infineon,slb9670"
+    "tcg,tpm_tis-spi"
+- spi-max-frequency: Maximum SPI frequency (depends on TPMs).
+
+Optional SoC Specific Properties:
+- pinctrl-names: Contains only one value - "default".
+- pintctrl-0: Specifies the pin control groups used for this controller.
+
+Example (for ARM-based BeagleBoard xM with TPM_TIS on SPI4):
+
+&mcspi4 {
+
+        status = "okay";
+
+        tpm_tis@0 {
+
+                compatible = "tcg,tpm_tis-spi";
+
+                spi-max-frequency = <10000000>;
+        };
+};

drivers/char/tpm/Kconfig

···
 	  within Linux. To compile this driver as a module, choose  M here;
 	  the module will be called tpm_tis.
 
+config TCG_TIS_SPI
+	tristate "TPM Interface Specification 1.3 Interface / TPM 2.0 FIFO Interface - (SPI)"
+	depends on SPI
+	select TCG_TIS_CORE
+	---help---
+	  If you have a TPM security chip which is connected to a regular,
+	  non-tcg SPI master (i.e. most embedded platforms) that is compliant with the
+	  TCG TIS 1.3 TPM specification (TPM1.2) or the TCG PTP FIFO
+	  specification (TPM2.0) say Yes and it will be accessible from
+	  within Linux. To compile this driver as a module, choose  M here;
+	  the module will be called tpm_tis_spi.
+
 config TCG_TIS_I2C_ATMEL
 	tristate "TPM Interface Specification 1.2 Interface (I2C - Atmel)"
 	depends on I2C

drivers/char/tpm/Makefile

···
 endif
 obj-$(CONFIG_TCG_TIS_CORE) += tpm_tis_core.o
 obj-$(CONFIG_TCG_TIS) += tpm_tis.o
+obj-$(CONFIG_TCG_TIS_SPI) += tpm_tis_spi.o
 obj-$(CONFIG_TCG_TIS_I2C_ATMEL) += tpm_i2c_atmel.o
 obj-$(CONFIG_TCG_TIS_I2C_INFINEON) += tpm_i2c_infineon.o
 obj-$(CONFIG_TCG_TIS_I2C_NUVOTON) += tpm_i2c_nuvoton.o

drivers/char/tpm/tpm_tis_spi.c

···
+/*
+ * Copyright (C) 2015 Infineon Technologies AG
+ * Copyright (C) 2016 STMicroelectronics SAS
+ *
+ * Authors:
+ * Peter Huewe <[e-mail]>
+ * Christophe Ricard <[e-mail]>
+ *
+ * Maintained by: <[e-mail]>
+ *
+ * Device driver for TCG/TCPA TPM (trusted platform module).
+ * Specifications at www.trustedcomputinggroup.org
+ *
+ * This device driver implements the TPM interface as defined in
+ * the TCG TPM Interface Spec version 1.3, revision 27 via _raw/native
+ * SPI access_.
+ *
+ * It is based on the original tpm_tis device driver from Leendert van
+ * Dorn and Kyleen Hall and Jarko Sakkinnen.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2 of the
+ * License.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/wait.h>
+#include <linux/acpi.h>
+#include <linux/freezer.h>
+
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+#include <linux/gpio.h>
+#include <linux/of_irq.h>
+#include <linux/of_gpio.h>
+#include <linux/tpm.h>
+#include "tpm.h"
+#include "tpm_tis_core.h"
+
+#define MAX_SPI_FRAMESIZE 64
+
+struct tpm_tis_spi_phy {
+	struct tpm_tis_data priv;
+	struct spi_device *spi_device;
+
+	u8 tx_buf[MAX_SPI_FRAMESIZE + 4];
+	u8 rx_buf[MAX_SPI_FRAMESIZE + 4];
+};
+
+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);
+}
+
+static int tpm_tis_spi_read_bytes(struct tpm_tis_data *data, u32 addr,
+				  u16 len, u8 *result)
+{
+	struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
+	int ret, i;
+	struct spi_message m;
+	struct spi_transfer spi_xfer = {
+		.tx_buf = phy->tx_buf,
+		.rx_buf = phy->rx_buf,
+		.len = 4,
+	};
+
+	if (len > MAX_SPI_FRAMESIZE)
+		return -ENOMEM;
+
+	phy->tx_buf[0] = 0x80 | (len - 1);
+	phy->tx_buf[1] = 0xd4;
+	phy->tx_buf[2] = (addr >> 8)  & 0xFF;
+	phy->tx_buf[3] = addr	      & 0xFF;
+
+	spi_xfer.cs_change = 1;
+	spi_message_init(&m);
+	spi_message_add_tail(&spi_xfer, &m);
+
+	spi_bus_lock(phy->spi_device->master);
+	ret = spi_sync_locked(phy->spi_device, &m);
+	if (ret < 0)
+		goto exit;
+
+	memset(phy->tx_buf, 0, len);
+
+	/* According to TCG PTP specification, if there is no TPM present at
+	 * all, then the design has a weak pull-up on MISO. If a TPM is not
+	 * present, a pull-up on MISO means that the SB controller sees a 1,
+	 * and will latch in 0xFF on the read.
+	 */
+	for (i = 0; (phy->rx_buf[0] & 0x01) == 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;
+	}
+
+	spi_xfer.cs_change = 0;
+	spi_xfer.len = len;
+	spi_xfer.rx_buf = result;
+
+	spi_message_init(&m);
+	spi_message_add_tail(&spi_xfer, &m);
+	ret = spi_sync_locked(phy->spi_device, &m);
+
+exit:
+	spi_bus_unlock(phy->spi_device->master);
+	return ret;
+}
+
+static int tpm_tis_spi_write_bytes(struct tpm_tis_data *data, u32 addr,
+				   u16 len, u8 *value)
+{
+	struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
+	int ret, i;
+	struct spi_message m;
+	struct spi_transfer spi_xfer = {
+		.tx_buf = phy->tx_buf,
+		.rx_buf = phy->rx_buf,
+		.len = 4,
+	};
+
+	if (len > MAX_SPI_FRAMESIZE)
+		return -ENOMEM;
+
+	phy->tx_buf[0] = len - 1;
+	phy->tx_buf[1] = 0xd4;
+	phy->tx_buf[2] = (addr >> 8)  & 0xFF;
+	phy->tx_buf[3] = addr         & 0xFF;
+
+	spi_xfer.cs_change = 1;
+	spi_message_init(&m);
+	spi_message_add_tail(&spi_xfer, &m);
+
+	spi_bus_lock(phy->spi_device->master);
+	ret = spi_sync_locked(phy->spi_device, &m);
+	if (ret < 0)
+		goto exit;
+
+	memset(phy->tx_buf, 0, len);
+
+	/* According to TCG PTP specification, if there is no TPM present at
+	 * all, then the design has a weak pull-up on MISO. If a TPM is not
+	 * present, a pull-up on MISO means that the SB controller sees a 1,
+	 * and will latch in 0xFF on the read.
+	 */
+	for (i = 0; (phy->rx_buf[0] & 0x01) == 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;
+	}
+
+	spi_xfer.len = len;
+	spi_xfer.tx_buf = value;
+	spi_xfer.cs_change = 0;
+	spi_xfer.tx_buf = value;
+	spi_message_init(&m);
+	spi_message_add_tail(&spi_xfer, &m);
+	ret = spi_sync_locked(phy->spi_device, &m);
+
+exit:
+	spi_bus_unlock(phy->spi_device->master);
+	return ret;
+}
+
+static int tpm_tis_spi_read16(struct tpm_tis_data *data, u32 addr, u16 *result)
+{
+	int rc;
+
+	rc = data->phy_ops->read_bytes(data, addr, sizeof(u16), (u8 *)result);
+	if (!rc)
+		*result = le16_to_cpu(*result);
+	return rc;
+}
+
+static int tpm_tis_spi_read32(struct tpm_tis_data *data, u32 addr, u32 *result)
+{
+	int rc;
+
+	rc = data->phy_ops->read_bytes(data, addr, sizeof(u32), (u8 *)result);
+	if (!rc)
+		*result = le32_to_cpu(*result);
+	return rc;
+}
+
+static int tpm_tis_spi_write32(struct tpm_tis_data *data, u32 addr, u32 value)
+{
+	value = cpu_to_le32(value);
+	return data->phy_ops->write_bytes(data, addr, sizeof(u32),
+					   (u8 *)&value);
+}
+
+static const struct tpm_tis_phy_ops tpm_spi_phy_ops = {
+	.read_bytes = tpm_tis_spi_read_bytes,
+	.write_bytes = tpm_tis_spi_write_bytes,
+	.read16 = tpm_tis_spi_read16,
+	.read32 = tpm_tis_spi_read32,
+	.write32 = tpm_tis_spi_write32,
+};
+
+static int tpm_tis_spi_probe(struct spi_device *dev)
+{
+	struct tpm_tis_spi_phy *phy;
+
+	phy = devm_kzalloc(&dev->dev, sizeof(struct tpm_tis_spi_phy),
+			   GFP_KERNEL);
+	if (!phy)
+		return -ENOMEM;
+
+	phy->spi_device = dev;
+
+	return tpm_tis_core_init(&dev->dev, &phy->priv, -1, &tpm_spi_phy_ops,
+				 NULL);
+}
+
+static SIMPLE_DEV_PM_OPS(tpm_tis_pm, tpm_pm_suspend, tpm_tis_resume);
+
+static int tpm_tis_spi_remove(struct spi_device *dev)
+{
+	struct tpm_chip *chip = spi_get_drvdata(dev);
+
+	tpm_chip_unregister(chip);
+	tpm_tis_remove(chip);
+	return 0;
+}
+
+static const struct spi_device_id tpm_tis_spi_id[] = {
+	{"tpm_tis_spi", 0},
+	{}
+};
+MODULE_DEVICE_TABLE(spi, tpm_tis_spi_id);
+
+static const struct of_device_id of_tis_spi_match[] = {
+	{ .compatible = "st,st33htpm-spi", },
+	{ .compatible = "infineon,slb9670", },
+	{ .compatible = "tcg,tpm_tis-spi", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, of_tis_spi_match);
+
+static const struct acpi_device_id acpi_tis_spi_match[] = {
+	{"SMO0768", 0},
+	{}
+};
+MODULE_DEVICE_TABLE(acpi, acpi_tis_spi_match);
+
+static struct spi_driver tpm_tis_spi_driver = {
+	.driver = {
+		.owner = THIS_MODULE,
+		.name = "tpm_tis_spi",
+		.pm = &tpm_tis_pm,
+		.of_match_table = of_match_ptr(of_tis_spi_match),
+		.acpi_match_table = ACPI_PTR(acpi_tis_spi_match),
+	},
+	.probe = tpm_tis_spi_probe,
+	.remove = tpm_tis_spi_remove,
+	.id_table = tpm_tis_spi_id,
+};
+module_spi_driver(tpm_tis_spi_driver);
+
+MODULE_DESCRIPTION("TPM Driver for native SPI access");
+MODULE_LICENSE("GPL");