1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (C) 2015 Infineon Technologies AG
  4 * Copyright (C) 2016 STMicroelectronics SAS
  5 *
  6 * Authors:
  7 * Peter Huewe <peter.huewe@infineon.com>
  8 * Christophe Ricard <christophe-h.ricard@st.com>
  9 *
 10 * Maintained by: <tpmdd-devel@lists.sourceforge.net>
 11 *
 12 * Device driver for TCG/TCPA TPM (trusted platform module).
 13 * Specifications at www.trustedcomputinggroup.org
 14 *
 15 * This device driver implements the TPM interface as defined in
 16 * the TCG TPM Interface Spec version 1.3, revision 27 via _raw/native
 17 * SPI access_.
 18 *
 19 * It is based on the original tpm_tis device driver from Leendert van
 20 * Dorn and Kyleen Hall and Jarko Sakkinnen.
 21 */
 22
 23#include <linux/acpi.h>
 24#include <linux/completion.h>
 25#include <linux/init.h>
 26#include <linux/interrupt.h>
 27#include <linux/kernel.h>
 28#include <linux/module.h>
 29#include <linux/slab.h>
 30
 31#include <linux/of_device.h>
 32#include <linux/spi/spi.h>
 33#include <linux/tpm.h>
 34
 35#include "tpm.h"
 36#include "tpm_tis_core.h"
 37#include "tpm_tis_spi.h"
 38
 39#define MAX_SPI_FRAMESIZE 64
 40
 41/*
 42 * TCG SPI flow control is documented in section 6.4 of the spec[1]. In short,
 43 * keep trying to read from the device until MISO goes high indicating the
 44 * wait state has ended.
 45 *
 46 * [1] https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
 47 */
 48static int tpm_tis_spi_flow_control(struct tpm_tis_spi_phy *phy,
 49				    struct spi_transfer *spi_xfer)
 50{
 51	struct spi_message m;
 52	int ret, i;
 53
 54	if ((phy->iobuf[3] & 0x01) == 0) {
 55		// handle SPI wait states
 56		for (i = 0; i < TPM_RETRY; i++) {
 57			spi_xfer->len = 1;
 58			spi_message_init(&m);
 59			spi_message_add_tail(spi_xfer, &m);
 60			ret = spi_sync_locked(phy->spi_device, &m);
 61			if (ret < 0)
 62				return ret;
 63			if (phy->iobuf[0] & 0x01)
 64				break;
 65		}
 66
 67		if (i == TPM_RETRY)
 68			return -ETIMEDOUT;
 69	}
 70
 71	return 0;
 72}
 73
 74int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
 75			 u8 *in, const u8 *out)
 76{
 77	struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
 78	int ret = 0;
 79	struct spi_message m;
 80	struct spi_transfer spi_xfer;
 81	u8 transfer_len;
 82
 83	spi_bus_lock(phy->spi_device->master);
 84
 85	while (len) {
 86		transfer_len = min_t(u16, len, MAX_SPI_FRAMESIZE);
 87
 88		phy->iobuf[0] = (in ? 0x80 : 0) | (transfer_len - 1);
 89		phy->iobuf[1] = 0xd4;
 90		phy->iobuf[2] = addr >> 8;
 91		phy->iobuf[3] = addr;
 92
 93		memset(&spi_xfer, 0, sizeof(spi_xfer));
 94		spi_xfer.tx_buf = phy->iobuf;
 95		spi_xfer.rx_buf = phy->iobuf;
 96		spi_xfer.len = 4;
 97		spi_xfer.cs_change = 1;
 98
 99		spi_message_init(&m);
100		spi_message_add_tail(&spi_xfer, &m);
101		ret = spi_sync_locked(phy->spi_device, &m);
102		if (ret < 0)
103			goto exit;
104
105		/* Flow control transfers are receive only */
106		spi_xfer.tx_buf = NULL;
107		ret = phy->flow_control(phy, &spi_xfer);
108		if (ret < 0)
109			goto exit;
110
111		spi_xfer.cs_change = 0;
112		spi_xfer.len = transfer_len;
113		spi_xfer.delay.value = 5;
114		spi_xfer.delay.unit = SPI_DELAY_UNIT_USECS;
115
116		if (out) {
117			spi_xfer.tx_buf = phy->iobuf;
118			spi_xfer.rx_buf = NULL;
119			memcpy(phy->iobuf, out, transfer_len);
120			out += transfer_len;
121		}
122
123		spi_message_init(&m);
124		spi_message_add_tail(&spi_xfer, &m);
125		reinit_completion(&phy->ready);
126		ret = spi_sync_locked(phy->spi_device, &m);
127		if (ret < 0)
128			goto exit;
129
130		if (in) {
131			memcpy(in, phy->iobuf, transfer_len);
132			in += transfer_len;
133		}
134
135		len -= transfer_len;
136	}
137
138exit:
139	spi_bus_unlock(phy->spi_device->master);
140	return ret;
141}
142
143static int tpm_tis_spi_read_bytes(struct tpm_tis_data *data, u32 addr,
144				  u16 len, u8 *result, enum tpm_tis_io_mode io_mode)
145{
146	return tpm_tis_spi_transfer(data, addr, len, result, NULL);
147}
148
149static int tpm_tis_spi_write_bytes(struct tpm_tis_data *data, u32 addr,
150				   u16 len, const u8 *value, enum tpm_tis_io_mode io_mode)
151{
152	return tpm_tis_spi_transfer(data, addr, len, NULL, value);
153}
154
155int tpm_tis_spi_init(struct spi_device *spi, struct tpm_tis_spi_phy *phy,
156		     int irq, const struct tpm_tis_phy_ops *phy_ops)
157{
158	phy->iobuf = devm_kmalloc(&spi->dev, MAX_SPI_FRAMESIZE, GFP_KERNEL);
159	if (!phy->iobuf)
160		return -ENOMEM;
161
162	phy->spi_device = spi;
163
164	return tpm_tis_core_init(&spi->dev, &phy->priv, irq, phy_ops, NULL);
165}
166
167static const struct tpm_tis_phy_ops tpm_spi_phy_ops = {
168	.read_bytes = tpm_tis_spi_read_bytes,
169	.write_bytes = tpm_tis_spi_write_bytes,
170};
171
172static int tpm_tis_spi_probe(struct spi_device *dev)
173{
174	struct tpm_tis_spi_phy *phy;
175	int irq;
176
177	phy = devm_kzalloc(&dev->dev, sizeof(struct tpm_tis_spi_phy),
178			   GFP_KERNEL);
179	if (!phy)
180		return -ENOMEM;
181
182	phy->flow_control = tpm_tis_spi_flow_control;
183
184	/* If the SPI device has an IRQ then use that */
185	if (dev->irq > 0)
186		irq = dev->irq;
187	else
188		irq = -1;
189
190	init_completion(&phy->ready);
191	return tpm_tis_spi_init(dev, phy, irq, &tpm_spi_phy_ops);
192}
193
194typedef int (*tpm_tis_spi_probe_func)(struct spi_device *);
195
196static int tpm_tis_spi_driver_probe(struct spi_device *spi)
197{
198	const struct spi_device_id *spi_dev_id = spi_get_device_id(spi);
199	tpm_tis_spi_probe_func probe_func;
200
201	probe_func = of_device_get_match_data(&spi->dev);
202	if (!probe_func) {
203		if (spi_dev_id) {
204			probe_func = (tpm_tis_spi_probe_func)spi_dev_id->driver_data;
205			if (!probe_func)
206				return -ENODEV;
207		} else
208			probe_func = tpm_tis_spi_probe;
209	}
210
211	return probe_func(spi);
212}
213
214static SIMPLE_DEV_PM_OPS(tpm_tis_pm, tpm_pm_suspend, tpm_tis_spi_resume);
215
216static void tpm_tis_spi_remove(struct spi_device *dev)
217{
218	struct tpm_chip *chip = spi_get_drvdata(dev);
219
220	tpm_chip_unregister(chip);
221	tpm_tis_remove(chip);
222}
223
224static const struct spi_device_id tpm_tis_spi_id[] = {
225	{ "st33htpm-spi", (unsigned long)tpm_tis_spi_probe },
226	{ "slb9670", (unsigned long)tpm_tis_spi_probe },
227	{ "tpm_tis_spi", (unsigned long)tpm_tis_spi_probe },
228	{ "tpm_tis-spi", (unsigned long)tpm_tis_spi_probe },
229	{ "cr50", (unsigned long)cr50_spi_probe },
230	{}
231};
232MODULE_DEVICE_TABLE(spi, tpm_tis_spi_id);
233
234static const struct of_device_id of_tis_spi_match[] = {
235	{ .compatible = "st,st33htpm-spi", .data = tpm_tis_spi_probe },
236	{ .compatible = "infineon,slb9670", .data = tpm_tis_spi_probe },
237	{ .compatible = "tcg,tpm_tis-spi", .data = tpm_tis_spi_probe },
238	{ .compatible = "google,cr50", .data = cr50_spi_probe },
239	{}
240};
241MODULE_DEVICE_TABLE(of, of_tis_spi_match);
242
243static const struct acpi_device_id acpi_tis_spi_match[] = {
244	{"SMO0768", 0},
245	{}
246};
247MODULE_DEVICE_TABLE(acpi, acpi_tis_spi_match);
248
249static struct spi_driver tpm_tis_spi_driver = {
250	.driver = {
251		.name = "tpm_tis_spi",
252		.pm = &tpm_tis_pm,
253		.of_match_table = of_match_ptr(of_tis_spi_match),
254		.acpi_match_table = ACPI_PTR(acpi_tis_spi_match),
255		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
256	},
257	.probe = tpm_tis_spi_driver_probe,
258	.remove = tpm_tis_spi_remove,
259	.id_table = tpm_tis_spi_id,
260};
261module_spi_driver(tpm_tis_spi_driver);
262
263MODULE_DESCRIPTION("TPM Driver for native SPI access");
264MODULE_LICENSE("GPL");