networking: add and use skb_put_u8()
[sfrench/cifs-2.6.git] / drivers / nfc / microread / i2c.c
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 hard_fault;         /*
54                                  * < 0 if hardware error occured (e.g. i2c err)
55                                  * and prevents normal operation.
56                                  */
57 };
58
59 #define I2C_DUMP_SKB(info, skb)                                 \
60 do {                                                            \
61         pr_debug("%s:\n", info);                                \
62         print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET, \
63                        16, 1, (skb)->data, (skb)->len, 0);      \
64 } while (0)
65
66 static void microread_i2c_add_len_crc(struct sk_buff *skb)
67 {
68         int i;
69         u8 crc = 0;
70         int len;
71
72         len = skb->len;
73         *(u8 *)skb_push(skb, 1) = len;
74
75         for (i = 0; i < skb->len; i++)
76                 crc = crc ^ skb->data[i];
77
78         skb_put_u8(skb, crc);
79 }
80
81 static void microread_i2c_remove_len_crc(struct sk_buff *skb)
82 {
83         skb_pull(skb, MICROREAD_I2C_FRAME_HEADROOM);
84         skb_trim(skb, MICROREAD_I2C_FRAME_TAILROOM);
85 }
86
87 static int check_crc(struct sk_buff *skb)
88 {
89         int i;
90         u8 crc = 0;
91
92         for (i = 0; i < skb->len - 1; i++)
93                 crc = crc ^ skb->data[i];
94
95         if (crc != skb->data[skb->len-1]) {
96                 pr_err("CRC error 0x%x != 0x%x\n", crc, skb->data[skb->len-1]);
97                 pr_info("%s: BAD CRC\n", __func__);
98                 return -EPERM;
99         }
100
101         return 0;
102 }
103
104 static int microread_i2c_enable(void *phy_id)
105 {
106         return 0;
107 }
108
109 static void microread_i2c_disable(void *phy_id)
110 {
111         return;
112 }
113
114 static int microread_i2c_write(void *phy_id, struct sk_buff *skb)
115 {
116         int r;
117         struct microread_i2c_phy *phy = phy_id;
118         struct i2c_client *client = phy->i2c_dev;
119
120         if (phy->hard_fault != 0)
121                 return phy->hard_fault;
122
123         usleep_range(3000, 6000);
124
125         microread_i2c_add_len_crc(skb);
126
127         I2C_DUMP_SKB("i2c frame written", skb);
128
129         r = i2c_master_send(client, skb->data, skb->len);
130
131         if (r == -EREMOTEIO) {  /* Retry, chip was in standby */
132                 usleep_range(6000, 10000);
133                 r = i2c_master_send(client, skb->data, skb->len);
134         }
135
136         if (r >= 0) {
137                 if (r != skb->len)
138                         r = -EREMOTEIO;
139                 else
140                         r = 0;
141         }
142
143         microread_i2c_remove_len_crc(skb);
144
145         return r;
146 }
147
148
149 static int microread_i2c_read(struct microread_i2c_phy *phy,
150                               struct sk_buff **skb)
151 {
152         int r;
153         u8 len;
154         u8 tmp[MICROREAD_I2C_LLC_MAX_SIZE - 1];
155         struct i2c_client *client = phy->i2c_dev;
156
157         r = i2c_master_recv(client, &len, 1);
158         if (r != 1) {
159                 nfc_err(&client->dev, "cannot read len byte\n");
160                 return -EREMOTEIO;
161         }
162
163         if ((len < MICROREAD_I2C_LLC_MIN_SIZE) ||
164             (len > MICROREAD_I2C_LLC_MAX_SIZE)) {
165                 nfc_err(&client->dev, "invalid len byte\n");
166                 r = -EBADMSG;
167                 goto flush;
168         }
169
170         *skb = alloc_skb(1 + len, GFP_KERNEL);
171         if (*skb == NULL) {
172                 r = -ENOMEM;
173                 goto flush;
174         }
175
176         skb_put_u8(*skb, len);
177
178         r = i2c_master_recv(client, skb_put(*skb, len), len);
179         if (r != len) {
180                 kfree_skb(*skb);
181                 return -EREMOTEIO;
182         }
183
184         I2C_DUMP_SKB("cc frame read", *skb);
185
186         r = check_crc(*skb);
187         if (r != 0) {
188                 kfree_skb(*skb);
189                 r = -EBADMSG;
190                 goto flush;
191         }
192
193         skb_pull(*skb, 1);
194         skb_trim(*skb, (*skb)->len - MICROREAD_I2C_FRAME_TAILROOM);
195
196         usleep_range(3000, 6000);
197
198         return 0;
199
200 flush:
201         if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0)
202                 r = -EREMOTEIO;
203
204         usleep_range(3000, 6000);
205
206         return r;
207 }
208
209 static irqreturn_t microread_i2c_irq_thread_fn(int irq, void *phy_id)
210 {
211         struct microread_i2c_phy *phy = phy_id;
212         struct sk_buff *skb = NULL;
213         int r;
214
215         if (!phy || irq != phy->i2c_dev->irq) {
216                 WARN_ON_ONCE(1);
217                 return IRQ_NONE;
218         }
219
220         if (phy->hard_fault != 0)
221                 return IRQ_HANDLED;
222
223         r = microread_i2c_read(phy, &skb);
224         if (r == -EREMOTEIO) {
225                 phy->hard_fault = r;
226
227                 nfc_hci_recv_frame(phy->hdev, NULL);
228
229                 return IRQ_HANDLED;
230         } else if ((r == -ENOMEM) || (r == -EBADMSG)) {
231                 return IRQ_HANDLED;
232         }
233
234         nfc_hci_recv_frame(phy->hdev, skb);
235
236         return IRQ_HANDLED;
237 }
238
239 static struct nfc_phy_ops i2c_phy_ops = {
240         .write = microread_i2c_write,
241         .enable = microread_i2c_enable,
242         .disable = microread_i2c_disable,
243 };
244
245 static int microread_i2c_probe(struct i2c_client *client,
246                                const struct i2c_device_id *id)
247 {
248         struct microread_i2c_phy *phy;
249         int r;
250
251         dev_dbg(&client->dev, "client %p\n", client);
252
253         phy = devm_kzalloc(&client->dev, sizeof(struct microread_i2c_phy),
254                            GFP_KERNEL);
255         if (!phy)
256                 return -ENOMEM;
257
258         i2c_set_clientdata(client, phy);
259         phy->i2c_dev = client;
260
261         r = request_threaded_irq(client->irq, NULL, microread_i2c_irq_thread_fn,
262                                  IRQF_TRIGGER_RISING | IRQF_ONESHOT,
263                                  MICROREAD_I2C_DRIVER_NAME, phy);
264         if (r) {
265                 nfc_err(&client->dev, "Unable to register IRQ handler\n");
266                 return r;
267         }
268
269         r = microread_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
270                             MICROREAD_I2C_FRAME_HEADROOM,
271                             MICROREAD_I2C_FRAME_TAILROOM,
272                             MICROREAD_I2C_LLC_MAX_PAYLOAD, &phy->hdev);
273         if (r < 0)
274                 goto err_irq;
275
276         nfc_info(&client->dev, "Probed\n");
277
278         return 0;
279
280 err_irq:
281         free_irq(client->irq, phy);
282
283         return r;
284 }
285
286 static int microread_i2c_remove(struct i2c_client *client)
287 {
288         struct microread_i2c_phy *phy = i2c_get_clientdata(client);
289
290         microread_remove(phy->hdev);
291
292         free_irq(client->irq, phy);
293
294         return 0;
295 }
296
297 static struct i2c_device_id microread_i2c_id[] = {
298         { MICROREAD_I2C_DRIVER_NAME, 0},
299         { }
300 };
301 MODULE_DEVICE_TABLE(i2c, microread_i2c_id);
302
303 static struct i2c_driver microread_i2c_driver = {
304         .driver = {
305                 .name = MICROREAD_I2C_DRIVER_NAME,
306         },
307         .probe          = microread_i2c_probe,
308         .remove         = microread_i2c_remove,
309         .id_table       = microread_i2c_id,
310 };
311
312 module_i2c_driver(microread_i2c_driver);
313
314 MODULE_LICENSE("GPL");
315 MODULE_DESCRIPTION(DRIVER_DESC);