1 /*
2 * HCI based Driver for Inside Secure microread NFC Chip - i2c layer
3 *
4 * Copyright (C) 2013 Intel Corporation. All rights reserved.
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms and conditions of the GNU General Public License,
8 * version 2, as published by the Free Software Foundation.
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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21 #include <linux/module.h>
22 #include <linux/i2c.h>
23 #include <linux/delay.h>
24 #include <linux/slab.h>
25 #include <linux/interrupt.h>
26 #include <linux/gpio.h>
27
28 #include <linux/nfc.h>
29 #include <net/nfc/hci.h>
30 #include <net/nfc/llc.h>
31
32 #include "microread.h"
33
34 #define MICROREAD_I2C_DRIVER_NAME "microread"
35
36 #define MICROREAD_I2C_FRAME_HEADROOM 1
37 #define MICROREAD_I2C_FRAME_TAILROOM 1
38
39 /* framing in HCI mode */
40 #define MICROREAD_I2C_LLC_LEN 1
41 #define MICROREAD_I2C_LLC_CRC 1
42 #define MICROREAD_I2C_LLC_LEN_CRC (MICROREAD_I2C_LLC_LEN + \
43 MICROREAD_I2C_LLC_CRC)
44 #define MICROREAD_I2C_LLC_MIN_SIZE (1 + MICROREAD_I2C_LLC_LEN_CRC)
45 #define MICROREAD_I2C_LLC_MAX_PAYLOAD 29
46 #define MICROREAD_I2C_LLC_MAX_SIZE (MICROREAD_I2C_LLC_LEN_CRC + 1 + \
47 MICROREAD_I2C_LLC_MAX_PAYLOAD)
48
49 struct microread_i2c_phy {
50 struct i2c_client *i2c_dev;
51 struct nfc_hci_dev *hdev;
52
53 int irq;
54
55 int hard_fault; /*
56 * < 0 if hardware error occured (e.g. i2c err)
57 * and prevents normal operation.
58 */
59 };
60
61 #define I2C_DUMP_SKB(info, skb) \
62 do { \
63 pr_debug("%s:\n", info); \
64 print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET, \
65 16, 1, (skb)->data, (skb)->len, 0); \
66 } while (0)
67
microread_i2c_add_len_crc(struct sk_buff * skb)68 static void microread_i2c_add_len_crc(struct sk_buff *skb)
69 {
70 int i;
71 u8 crc = 0;
72 int len;
73
74 len = skb->len;
75 *skb_push(skb, 1) = len;
76
77 for (i = 0; i < skb->len; i++)
78 crc = crc ^ skb->data[i];
79
80 *skb_put(skb, 1) = crc;
81 }
82
microread_i2c_remove_len_crc(struct sk_buff * skb)83 static void microread_i2c_remove_len_crc(struct sk_buff *skb)
84 {
85 skb_pull(skb, MICROREAD_I2C_FRAME_HEADROOM);
86 skb_trim(skb, MICROREAD_I2C_FRAME_TAILROOM);
87 }
88
check_crc(struct sk_buff * skb)89 static int check_crc(struct sk_buff *skb)
90 {
91 int i;
92 u8 crc = 0;
93
94 for (i = 0; i < skb->len - 1; i++)
95 crc = crc ^ skb->data[i];
96
97 if (crc != skb->data[skb->len-1]) {
98 pr_err("CRC error 0x%x != 0x%x\n", crc, skb->data[skb->len-1]);
99 pr_info("%s: BAD CRC\n", __func__);
100 return -EPERM;
101 }
102
103 return 0;
104 }
105
microread_i2c_enable(void * phy_id)106 static int microread_i2c_enable(void *phy_id)
107 {
108 return 0;
109 }
110
microread_i2c_disable(void * phy_id)111 static void microread_i2c_disable(void *phy_id)
112 {
113 return;
114 }
115
microread_i2c_write(void * phy_id,struct sk_buff * skb)116 static int microread_i2c_write(void *phy_id, struct sk_buff *skb)
117 {
118 int r;
119 struct microread_i2c_phy *phy = phy_id;
120 struct i2c_client *client = phy->i2c_dev;
121
122 if (phy->hard_fault != 0)
123 return phy->hard_fault;
124
125 usleep_range(3000, 6000);
126
127 microread_i2c_add_len_crc(skb);
128
129 I2C_DUMP_SKB("i2c frame written", skb);
130
131 r = i2c_master_send(client, skb->data, skb->len);
132
133 if (r == -EREMOTEIO) { /* Retry, chip was in standby */
134 usleep_range(6000, 10000);
135 r = i2c_master_send(client, skb->data, skb->len);
136 }
137
138 if (r >= 0) {
139 if (r != skb->len)
140 r = -EREMOTEIO;
141 else
142 r = 0;
143 }
144
145 microread_i2c_remove_len_crc(skb);
146
147 return r;
148 }
149
150
microread_i2c_read(struct microread_i2c_phy * phy,struct sk_buff ** skb)151 static int microread_i2c_read(struct microread_i2c_phy *phy,
152 struct sk_buff **skb)
153 {
154 int r;
155 u8 len;
156 u8 tmp[MICROREAD_I2C_LLC_MAX_SIZE - 1];
157 struct i2c_client *client = phy->i2c_dev;
158
159 r = i2c_master_recv(client, &len, 1);
160 if (r != 1) {
161 nfc_err(&client->dev, "cannot read len byte\n");
162 return -EREMOTEIO;
163 }
164
165 if ((len < MICROREAD_I2C_LLC_MIN_SIZE) ||
166 (len > MICROREAD_I2C_LLC_MAX_SIZE)) {
167 nfc_err(&client->dev, "invalid len byte\n");
168 r = -EBADMSG;
169 goto flush;
170 }
171
172 *skb = alloc_skb(1 + len, GFP_KERNEL);
173 if (*skb == NULL) {
174 r = -ENOMEM;
175 goto flush;
176 }
177
178 *skb_put(*skb, 1) = len;
179
180 r = i2c_master_recv(client, skb_put(*skb, len), len);
181 if (r != len) {
182 kfree_skb(*skb);
183 return -EREMOTEIO;
184 }
185
186 I2C_DUMP_SKB("cc frame read", *skb);
187
188 r = check_crc(*skb);
189 if (r != 0) {
190 kfree_skb(*skb);
191 r = -EBADMSG;
192 goto flush;
193 }
194
195 skb_pull(*skb, 1);
196 skb_trim(*skb, (*skb)->len - MICROREAD_I2C_FRAME_TAILROOM);
197
198 usleep_range(3000, 6000);
199
200 return 0;
201
202 flush:
203 if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0)
204 r = -EREMOTEIO;
205
206 usleep_range(3000, 6000);
207
208 return r;
209 }
210
microread_i2c_irq_thread_fn(int irq,void * phy_id)211 static irqreturn_t microread_i2c_irq_thread_fn(int irq, void *phy_id)
212 {
213 struct microread_i2c_phy *phy = phy_id;
214 struct sk_buff *skb = NULL;
215 int r;
216
217 if (!phy || irq != phy->i2c_dev->irq) {
218 WARN_ON_ONCE(1);
219 return IRQ_NONE;
220 }
221
222 if (phy->hard_fault != 0)
223 return IRQ_HANDLED;
224
225 r = microread_i2c_read(phy, &skb);
226 if (r == -EREMOTEIO) {
227 phy->hard_fault = r;
228
229 nfc_hci_recv_frame(phy->hdev, NULL);
230
231 return IRQ_HANDLED;
232 } else if ((r == -ENOMEM) || (r == -EBADMSG)) {
233 return IRQ_HANDLED;
234 }
235
236 nfc_hci_recv_frame(phy->hdev, skb);
237
238 return IRQ_HANDLED;
239 }
240
241 static struct nfc_phy_ops i2c_phy_ops = {
242 .write = microread_i2c_write,
243 .enable = microread_i2c_enable,
244 .disable = microread_i2c_disable,
245 };
246
microread_i2c_probe(struct i2c_client * client,const struct i2c_device_id * id)247 static int microread_i2c_probe(struct i2c_client *client,
248 const struct i2c_device_id *id)
249 {
250 struct microread_i2c_phy *phy;
251 struct microread_nfc_platform_data *pdata =
252 dev_get_platdata(&client->dev);
253 int r;
254
255 dev_dbg(&client->dev, "client %p\n", client);
256
257 if (!pdata) {
258 nfc_err(&client->dev, "client %p: missing platform data\n",
259 client);
260 return -EINVAL;
261 }
262
263 phy = devm_kzalloc(&client->dev, sizeof(struct microread_i2c_phy),
264 GFP_KERNEL);
265 if (!phy)
266 return -ENOMEM;
267
268 i2c_set_clientdata(client, phy);
269 phy->i2c_dev = client;
270
271 r = request_threaded_irq(client->irq, NULL, microread_i2c_irq_thread_fn,
272 IRQF_TRIGGER_RISING | IRQF_ONESHOT,
273 MICROREAD_I2C_DRIVER_NAME, phy);
274 if (r) {
275 nfc_err(&client->dev, "Unable to register IRQ handler\n");
276 return r;
277 }
278
279 r = microread_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
280 MICROREAD_I2C_FRAME_HEADROOM,
281 MICROREAD_I2C_FRAME_TAILROOM,
282 MICROREAD_I2C_LLC_MAX_PAYLOAD, &phy->hdev);
283 if (r < 0)
284 goto err_irq;
285
286 nfc_info(&client->dev, "Probed\n");
287
288 return 0;
289
290 err_irq:
291 free_irq(client->irq, phy);
292
293 return r;
294 }
295
microread_i2c_remove(struct i2c_client * client)296 static int microread_i2c_remove(struct i2c_client *client)
297 {
298 struct microread_i2c_phy *phy = i2c_get_clientdata(client);
299
300 microread_remove(phy->hdev);
301
302 free_irq(client->irq, phy);
303
304 return 0;
305 }
306
307 static struct i2c_device_id microread_i2c_id[] = {
308 { MICROREAD_I2C_DRIVER_NAME, 0},
309 { }
310 };
311 MODULE_DEVICE_TABLE(i2c, microread_i2c_id);
312
313 static struct i2c_driver microread_i2c_driver = {
314 .driver = {
315 .name = MICROREAD_I2C_DRIVER_NAME,
316 },
317 .probe = microread_i2c_probe,
318 .remove = microread_i2c_remove,
319 .id_table = microread_i2c_id,
320 };
321
322 module_i2c_driver(microread_i2c_driver);
323
324 MODULE_LICENSE("GPL");
325 MODULE_DESCRIPTION(DRIVER_DESC);
326