1/*
2 * STMicroelectronics TPM SPI Linux driver for TPM ST33ZP24
3 * Copyright (C) 2009 - 2015  STMicroelectronics
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, see <http://www.gnu.org/licenses/>.
17 */
18
19#include <linux/module.h>
20#include <linux/spi/spi.h>
21#include <linux/gpio.h>
22#include <linux/of_irq.h>
23#include <linux/of_gpio.h>
24#include <linux/tpm.h>
25#include <linux/platform_data/st33zp24.h>
26
27#include "st33zp24.h"
28
29#define TPM_DATA_FIFO           0x24
30#define TPM_INTF_CAPABILITY     0x14
31
32#define TPM_DUMMY_BYTE		0x00
33
34#define MAX_SPI_LATENCY		15
35#define LOCALITY0		0
36
37#define ST33ZP24_OK					0x5A
38#define ST33ZP24_UNDEFINED_ERR				0x80
39#define ST33ZP24_BADLOCALITY				0x81
40#define ST33ZP24_TISREGISTER_UKNOWN			0x82
41#define ST33ZP24_LOCALITY_NOT_ACTIVATED			0x83
42#define ST33ZP24_HASH_END_BEFORE_HASH_START		0x84
43#define ST33ZP24_BAD_COMMAND_ORDER			0x85
44#define ST33ZP24_INCORECT_RECEIVED_LENGTH		0x86
45#define ST33ZP24_TPM_FIFO_OVERFLOW			0x89
46#define ST33ZP24_UNEXPECTED_READ_FIFO			0x8A
47#define ST33ZP24_UNEXPECTED_WRITE_FIFO			0x8B
48#define ST33ZP24_CMDRDY_SET_WHEN_PROCESSING_HASH_END	0x90
49#define ST33ZP24_DUMMY_BYTES				0x00
50
51/*
52 * TPM command can be up to 2048 byte, A TPM response can be up to
53 * 1024 byte.
54 * Between command and response, there are latency byte (up to 15
55 * usually on st33zp24 2 are enough).
56 *
57 * Overall when sending a command and expecting an answer we need if
58 * worst case:
59 * 2048 (for the TPM command) + 1024 (for the TPM answer).  We need
60 * some latency byte before the answer is available (max 15).
61 * We have 2048 + 1024 + 15.
62 */
63#define ST33ZP24_SPI_BUFFER_SIZE (TPM_BUFSIZE + (TPM_BUFSIZE / 2) +\
64				  MAX_SPI_LATENCY)
65
66
67struct st33zp24_spi_phy {
68	struct spi_device *spi_device;
69	struct spi_transfer spi_xfer;
70	u8 tx_buf[ST33ZP24_SPI_BUFFER_SIZE];
71	u8 rx_buf[ST33ZP24_SPI_BUFFER_SIZE];
72
73	int io_lpcpd;
74	int latency;
75};
76
77static int st33zp24_status_to_errno(u8 code)
78{
79	switch (code) {
80	case ST33ZP24_OK:
81		return 0;
82	case ST33ZP24_UNDEFINED_ERR:
83	case ST33ZP24_BADLOCALITY:
84	case ST33ZP24_TISREGISTER_UKNOWN:
85	case ST33ZP24_LOCALITY_NOT_ACTIVATED:
86	case ST33ZP24_HASH_END_BEFORE_HASH_START:
87	case ST33ZP24_BAD_COMMAND_ORDER:
88	case ST33ZP24_UNEXPECTED_READ_FIFO:
89	case ST33ZP24_UNEXPECTED_WRITE_FIFO:
90	case ST33ZP24_CMDRDY_SET_WHEN_PROCESSING_HASH_END:
91		return -EPROTO;
92	case ST33ZP24_INCORECT_RECEIVED_LENGTH:
93	case ST33ZP24_TPM_FIFO_OVERFLOW:
94		return -EMSGSIZE;
95	case ST33ZP24_DUMMY_BYTES:
96		return -ENOSYS;
97	}
98	return code;
99}
100
101/*
102 * st33zp24_spi_send
103 * Send byte to the TIS register according to the ST33ZP24 SPI protocol.
104 * @param: phy_id, the phy description
105 * @param: tpm_register, the tpm tis register where the data should be written
106 * @param: tpm_data, the tpm_data to write inside the tpm_register
107 * @param: tpm_size, The length of the data
108 * @return: should be zero if success else a negative error code.
109 */
110static int st33zp24_spi_send(void *phy_id, u8 tpm_register, u8 *tpm_data,
111			     int tpm_size)
112{
113	u8 data = 0;
114	int total_length = 0, nbr_dummy_bytes = 0, ret = 0;
115	struct st33zp24_spi_phy *phy = phy_id;
116	struct spi_device *dev = phy->spi_device;
117	u8 *tx_buf = (u8 *)phy->spi_xfer.tx_buf;
118	u8 *rx_buf = phy->spi_xfer.rx_buf;
119
120	/* Pre-Header */
121	data = TPM_WRITE_DIRECTION | LOCALITY0;
122	memcpy(tx_buf + total_length, &data, sizeof(data));
123	total_length++;
124	data = tpm_register;
125	memcpy(tx_buf + total_length, &data, sizeof(data));
126	total_length++;
127
128	if (tpm_size > 0 && tpm_register == TPM_DATA_FIFO) {
129		tx_buf[total_length++] = tpm_size >> 8;
130		tx_buf[total_length++] = tpm_size;
131	}
132
133	memcpy(&tx_buf[total_length], tpm_data, tpm_size);
134	total_length += tpm_size;
135
136	nbr_dummy_bytes = phy->latency;
137	memset(&tx_buf[total_length], TPM_DUMMY_BYTE, nbr_dummy_bytes);
138
139	phy->spi_xfer.len = total_length + nbr_dummy_bytes;
140
141	ret = spi_sync_transfer(dev, &phy->spi_xfer, 1);
142	if (ret == 0)
143		ret = rx_buf[total_length + nbr_dummy_bytes - 1];
144
145	return st33zp24_status_to_errno(ret);
146} /* st33zp24_spi_send() */
147
148/*
149 * read8_recv
150 * Recv byte from the TIS register according to the ST33ZP24 SPI protocol.
151 * @param: phy_id, the phy description
152 * @param: tpm_register, the tpm tis register where the data should be read
153 * @param: tpm_data, the TPM response
154 * @param: tpm_size, tpm TPM response size to read.
155 * @return: should be zero if success else a negative error code.
156 */
157static int read8_reg(void *phy_id, u8 tpm_register, u8 *tpm_data, int tpm_size)
158{
159	u8 data = 0;
160	int total_length = 0, nbr_dummy_bytes, ret;
161	struct st33zp24_spi_phy *phy = phy_id;
162	struct spi_device *dev = phy->spi_device;
163	u8 *tx_buf = (u8 *)phy->spi_xfer.tx_buf;
164	u8 *rx_buf = phy->spi_xfer.rx_buf;
165
166	/* Pre-Header */
167	data = LOCALITY0;
168	memcpy(tx_buf + total_length, &data, sizeof(data));
169	total_length++;
170	data = tpm_register;
171	memcpy(tx_buf + total_length, &data, sizeof(data));
172	total_length++;
173
174	nbr_dummy_bytes = phy->latency;
175	memset(&tx_buf[total_length], TPM_DUMMY_BYTE,
176	       nbr_dummy_bytes + tpm_size);
177
178	phy->spi_xfer.len = total_length + nbr_dummy_bytes + tpm_size;
179
180	/* header + status byte + size of the data + status byte */
181	ret = spi_sync_transfer(dev, &phy->spi_xfer, 1);
182	if (tpm_size > 0 && ret == 0) {
183		ret = rx_buf[total_length + nbr_dummy_bytes - 1];
184
185		memcpy(tpm_data, rx_buf + total_length + nbr_dummy_bytes,
186		       tpm_size);
187	}
188
189	return ret;
190} /* read8_reg() */
191
192/*
193 * st33zp24_spi_recv
194 * Recv byte from the TIS register according to the ST33ZP24 SPI protocol.
195 * @param: phy_id, the phy description
196 * @param: tpm_register, the tpm tis register where the data should be read
197 * @param: tpm_data, the TPM response
198 * @param: tpm_size, tpm TPM response size to read.
199 * @return: number of byte read successfully: should be one if success.
200 */
201static int st33zp24_spi_recv(void *phy_id, u8 tpm_register, u8 *tpm_data,
202			     int tpm_size)
203{
204	int ret;
205
206	ret = read8_reg(phy_id, tpm_register, tpm_data, tpm_size);
207	if (!st33zp24_status_to_errno(ret))
208		return tpm_size;
209	return ret;
210} /* st33zp24_spi_recv() */
211
212static int evaluate_latency(void *phy_id)
213{
214	struct st33zp24_spi_phy *phy = phy_id;
215	int latency = 1, status = 0;
216	u8 data = 0;
217
218	while (!status && latency < MAX_SPI_LATENCY) {
219		phy->latency = latency;
220		status = read8_reg(phy_id, TPM_INTF_CAPABILITY, &data, 1);
221		latency++;
222	}
223	return latency - 1;
224} /* evaluate_latency() */
225
226static const struct st33zp24_phy_ops spi_phy_ops = {
227	.send = st33zp24_spi_send,
228	.recv = st33zp24_spi_recv,
229};
230
231#ifdef CONFIG_OF
232static int tpm_stm_spi_of_request_resources(struct st33zp24_spi_phy *phy)
233{
234	struct device_node *pp;
235	struct spi_device *dev = phy->spi_device;
236	int gpio;
237	int ret;
238
239	pp = dev->dev.of_node;
240	if (!pp) {
241		dev_err(&dev->dev, "No platform data\n");
242		return -ENODEV;
243	}
244
245	/* Get GPIO from device tree */
246	gpio = of_get_named_gpio(pp, "lpcpd-gpios", 0);
247	if (gpio < 0) {
248		dev_err(&dev->dev,
249			"Failed to retrieve lpcpd-gpios from dts.\n");
250		phy->io_lpcpd = -1;
251		/*
252		 * lpcpd pin is not specified. This is not an issue as
253		 * power management can be also managed by TPM specific
254		 * commands. So leave with a success status code.
255		 */
256		return 0;
257	}
258	/* GPIO request and configuration */
259	ret = devm_gpio_request_one(&dev->dev, gpio,
260			GPIOF_OUT_INIT_HIGH, "TPM IO LPCPD");
261	if (ret) {
262		dev_err(&dev->dev, "Failed to request lpcpd pin\n");
263		return -ENODEV;
264	}
265	phy->io_lpcpd = gpio;
266
267	return 0;
268}
269#else
270static int tpm_stm_spi_of_request_resources(struct st33zp24_spi_phy *phy)
271{
272	return -ENODEV;
273}
274#endif
275
276static int tpm_stm_spi_request_resources(struct spi_device *dev,
277					 struct st33zp24_spi_phy *phy)
278{
279	struct st33zp24_platform_data *pdata;
280	int ret;
281
282	pdata = dev->dev.platform_data;
283	if (!pdata) {
284		dev_err(&dev->dev, "No platform data\n");
285		return -ENODEV;
286	}
287
288	/* store for late use */
289	phy->io_lpcpd = pdata->io_lpcpd;
290
291	if (gpio_is_valid(pdata->io_lpcpd)) {
292		ret = devm_gpio_request_one(&dev->dev,
293				pdata->io_lpcpd, GPIOF_OUT_INIT_HIGH,
294				"TPM IO_LPCPD");
295		if (ret) {
296			dev_err(&dev->dev, "%s : reset gpio_request failed\n",
297				__FILE__);
298			return ret;
299		}
300	}
301
302	return 0;
303}
304
305/*
306 * tpm_st33_spi_probe initialize the TPM device
307 * @param: dev, the spi_device drescription (TPM SPI description).
308 * @return: 0 in case of success.
309 *	 or a negative value describing the error.
310 */
311static int
312tpm_st33_spi_probe(struct spi_device *dev)
313{
314	int ret;
315	struct st33zp24_platform_data *pdata;
316	struct st33zp24_spi_phy *phy;
317
318	/* Check SPI platform functionnalities */
319	if (!dev) {
320		pr_info("%s: dev is NULL. Device is not accessible.\n",
321			__func__);
322		return -ENODEV;
323	}
324
325	phy = devm_kzalloc(&dev->dev, sizeof(struct st33zp24_spi_phy),
326			   GFP_KERNEL);
327	if (!phy)
328		return -ENOMEM;
329
330	phy->spi_device = dev;
331	pdata = dev->dev.platform_data;
332	if (!pdata && dev->dev.of_node) {
333		ret = tpm_stm_spi_of_request_resources(phy);
334		if (ret)
335			return ret;
336	} else if (pdata) {
337		ret = tpm_stm_spi_request_resources(dev, phy);
338		if (ret)
339			return ret;
340	}
341
342	phy->spi_xfer.tx_buf = phy->tx_buf;
343	phy->spi_xfer.rx_buf = phy->rx_buf;
344
345	phy->latency = evaluate_latency(phy);
346	if (phy->latency <= 0)
347		return -ENODEV;
348
349	return st33zp24_probe(phy, &spi_phy_ops, &dev->dev, dev->irq,
350			      phy->io_lpcpd);
351}
352
353/*
354 * tpm_st33_spi_remove remove the TPM device
355 * @param: client, the spi_device drescription (TPM SPI description).
356 * @return: 0 in case of success.
357 */
358static int tpm_st33_spi_remove(struct spi_device *dev)
359{
360	struct tpm_chip *chip = spi_get_drvdata(dev);
361
362	return st33zp24_remove(chip);
363}
364
365static const struct spi_device_id st33zp24_spi_id[] = {
366	{TPM_ST33_SPI, 0},
367	{}
368};
369MODULE_DEVICE_TABLE(spi, st33zp24_spi_id);
370
371#ifdef CONFIG_OF
372static const struct of_device_id of_st33zp24_spi_match[] = {
373	{ .compatible = "st,st33zp24-spi", },
374	{}
375};
376MODULE_DEVICE_TABLE(of, of_st33zp24_spi_match);
377#endif
378
379static SIMPLE_DEV_PM_OPS(st33zp24_spi_ops, st33zp24_pm_suspend,
380			 st33zp24_pm_resume);
381
382static struct spi_driver tpm_st33_spi_driver = {
383	.driver = {
384		.owner = THIS_MODULE,
385		.name = TPM_ST33_SPI,
386		.pm = &st33zp24_spi_ops,
387		.of_match_table = of_match_ptr(of_st33zp24_spi_match),
388	},
389	.probe = tpm_st33_spi_probe,
390	.remove = tpm_st33_spi_remove,
391	.id_table = st33zp24_spi_id,
392};
393
394module_spi_driver(tpm_st33_spi_driver);
395
396MODULE_AUTHOR("TPM support (TPMsupport@list.st.com)");
397MODULE_DESCRIPTION("STM TPM 1.2 SPI ST33 Driver");
398MODULE_VERSION("1.3.0");
399MODULE_LICENSE("GPL");
400