1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * HCI based Driver for Inside Secure microread NFC Chip - i2c layer |
4 | * |
5 | * Copyright (C) 2013 Intel Corporation. All rights reserved. |
6 | */ |
7 | |
8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
9 | |
10 | #include <linux/module.h> |
11 | #include <linux/i2c.h> |
12 | #include <linux/delay.h> |
13 | #include <linux/slab.h> |
14 | #include <linux/interrupt.h> |
15 | #include <linux/gpio.h> |
16 | |
17 | #include <linux/nfc.h> |
18 | #include <net/nfc/hci.h> |
19 | #include <net/nfc/llc.h> |
20 | |
21 | #include "microread.h" |
22 | |
23 | #define MICROREAD_I2C_DRIVER_NAME "microread" |
24 | |
25 | #define MICROREAD_I2C_FRAME_HEADROOM 1 |
26 | #define MICROREAD_I2C_FRAME_TAILROOM 1 |
27 | |
28 | /* framing in HCI mode */ |
29 | #define MICROREAD_I2C_LLC_LEN 1 |
30 | #define MICROREAD_I2C_LLC_CRC 1 |
31 | #define MICROREAD_I2C_LLC_LEN_CRC (MICROREAD_I2C_LLC_LEN + \ |
32 | MICROREAD_I2C_LLC_CRC) |
33 | #define MICROREAD_I2C_LLC_MIN_SIZE (1 + MICROREAD_I2C_LLC_LEN_CRC) |
34 | #define MICROREAD_I2C_LLC_MAX_PAYLOAD 29 |
35 | #define MICROREAD_I2C_LLC_MAX_SIZE (MICROREAD_I2C_LLC_LEN_CRC + 1 + \ |
36 | MICROREAD_I2C_LLC_MAX_PAYLOAD) |
37 | |
38 | struct microread_i2c_phy { |
39 | struct i2c_client *i2c_dev; |
40 | struct nfc_hci_dev *hdev; |
41 | |
42 | int hard_fault; /* |
43 | * < 0 if hardware error occured (e.g. i2c err) |
44 | * and prevents normal operation. |
45 | */ |
46 | }; |
47 | |
48 | #define I2C_DUMP_SKB(info, skb) \ |
49 | do { \ |
50 | pr_debug("%s:\n", info); \ |
51 | print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET, \ |
52 | 16, 1, (skb)->data, (skb)->len, 0); \ |
53 | } while (0) |
54 | |
55 | static void microread_i2c_add_len_crc(struct sk_buff *skb) |
56 | { |
57 | int i; |
58 | u8 crc = 0; |
59 | int len; |
60 | |
61 | len = skb->len; |
62 | *(u8 *)skb_push(skb, len: 1) = len; |
63 | |
64 | for (i = 0; i < skb->len; i++) |
65 | crc = crc ^ skb->data[i]; |
66 | |
67 | skb_put_u8(skb, val: crc); |
68 | } |
69 | |
70 | static void microread_i2c_remove_len_crc(struct sk_buff *skb) |
71 | { |
72 | skb_pull(skb, MICROREAD_I2C_FRAME_HEADROOM); |
73 | skb_trim(skb, MICROREAD_I2C_FRAME_TAILROOM); |
74 | } |
75 | |
76 | static int check_crc(const struct sk_buff *skb) |
77 | { |
78 | int i; |
79 | u8 crc = 0; |
80 | |
81 | for (i = 0; i < skb->len - 1; i++) |
82 | crc = crc ^ skb->data[i]; |
83 | |
84 | if (crc != skb->data[skb->len-1]) { |
85 | pr_err("CRC error 0x%x != 0x%x\n" , crc, skb->data[skb->len-1]); |
86 | pr_info("%s: BAD CRC\n" , __func__); |
87 | return -EPERM; |
88 | } |
89 | |
90 | return 0; |
91 | } |
92 | |
93 | static int microread_i2c_enable(void *phy_id) |
94 | { |
95 | return 0; |
96 | } |
97 | |
98 | static void microread_i2c_disable(void *phy_id) |
99 | { |
100 | return; |
101 | } |
102 | |
103 | static int microread_i2c_write(void *phy_id, struct sk_buff *skb) |
104 | { |
105 | int r; |
106 | struct microread_i2c_phy *phy = phy_id; |
107 | struct i2c_client *client = phy->i2c_dev; |
108 | |
109 | if (phy->hard_fault != 0) |
110 | return phy->hard_fault; |
111 | |
112 | usleep_range(min: 3000, max: 6000); |
113 | |
114 | microread_i2c_add_len_crc(skb); |
115 | |
116 | I2C_DUMP_SKB("i2c frame written" , skb); |
117 | |
118 | r = i2c_master_send(client, buf: skb->data, count: skb->len); |
119 | |
120 | if (r == -EREMOTEIO) { /* Retry, chip was in standby */ |
121 | usleep_range(min: 6000, max: 10000); |
122 | r = i2c_master_send(client, buf: skb->data, count: skb->len); |
123 | } |
124 | |
125 | if (r >= 0) { |
126 | if (r != skb->len) |
127 | r = -EREMOTEIO; |
128 | else |
129 | r = 0; |
130 | } |
131 | |
132 | microread_i2c_remove_len_crc(skb); |
133 | |
134 | return r; |
135 | } |
136 | |
137 | |
138 | static int microread_i2c_read(struct microread_i2c_phy *phy, |
139 | struct sk_buff **skb) |
140 | { |
141 | int r; |
142 | u8 len; |
143 | u8 tmp[MICROREAD_I2C_LLC_MAX_SIZE - 1]; |
144 | struct i2c_client *client = phy->i2c_dev; |
145 | |
146 | r = i2c_master_recv(client, buf: &len, count: 1); |
147 | if (r != 1) { |
148 | nfc_err(&client->dev, "cannot read len byte\n" ); |
149 | return -EREMOTEIO; |
150 | } |
151 | |
152 | if ((len < MICROREAD_I2C_LLC_MIN_SIZE) || |
153 | (len > MICROREAD_I2C_LLC_MAX_SIZE)) { |
154 | nfc_err(&client->dev, "invalid len byte\n" ); |
155 | r = -EBADMSG; |
156 | goto flush; |
157 | } |
158 | |
159 | *skb = alloc_skb(size: 1 + len, GFP_KERNEL); |
160 | if (*skb == NULL) { |
161 | r = -ENOMEM; |
162 | goto flush; |
163 | } |
164 | |
165 | skb_put_u8(skb: *skb, val: len); |
166 | |
167 | r = i2c_master_recv(client, buf: skb_put(skb: *skb, len), count: len); |
168 | if (r != len) { |
169 | kfree_skb(skb: *skb); |
170 | return -EREMOTEIO; |
171 | } |
172 | |
173 | I2C_DUMP_SKB("cc frame read" , *skb); |
174 | |
175 | r = check_crc(skb: *skb); |
176 | if (r != 0) { |
177 | kfree_skb(skb: *skb); |
178 | r = -EBADMSG; |
179 | goto flush; |
180 | } |
181 | |
182 | skb_pull(skb: *skb, len: 1); |
183 | skb_trim(skb: *skb, len: (*skb)->len - MICROREAD_I2C_FRAME_TAILROOM); |
184 | |
185 | usleep_range(min: 3000, max: 6000); |
186 | |
187 | return 0; |
188 | |
189 | flush: |
190 | if (i2c_master_recv(client, buf: tmp, count: sizeof(tmp)) < 0) |
191 | r = -EREMOTEIO; |
192 | |
193 | usleep_range(min: 3000, max: 6000); |
194 | |
195 | return r; |
196 | } |
197 | |
198 | static irqreturn_t microread_i2c_irq_thread_fn(int irq, void *phy_id) |
199 | { |
200 | struct microread_i2c_phy *phy = phy_id; |
201 | struct sk_buff *skb = NULL; |
202 | int r; |
203 | |
204 | if (!phy || irq != phy->i2c_dev->irq) { |
205 | WARN_ON_ONCE(1); |
206 | return IRQ_NONE; |
207 | } |
208 | |
209 | if (phy->hard_fault != 0) |
210 | return IRQ_HANDLED; |
211 | |
212 | r = microread_i2c_read(phy, skb: &skb); |
213 | if (r == -EREMOTEIO) { |
214 | phy->hard_fault = r; |
215 | |
216 | nfc_hci_recv_frame(hdev: phy->hdev, NULL); |
217 | |
218 | return IRQ_HANDLED; |
219 | } else if ((r == -ENOMEM) || (r == -EBADMSG)) { |
220 | return IRQ_HANDLED; |
221 | } |
222 | |
223 | nfc_hci_recv_frame(hdev: phy->hdev, skb); |
224 | |
225 | return IRQ_HANDLED; |
226 | } |
227 | |
228 | static const struct nfc_phy_ops i2c_phy_ops = { |
229 | .write = microread_i2c_write, |
230 | .enable = microread_i2c_enable, |
231 | .disable = microread_i2c_disable, |
232 | }; |
233 | |
234 | static int microread_i2c_probe(struct i2c_client *client) |
235 | { |
236 | struct microread_i2c_phy *phy; |
237 | int r; |
238 | |
239 | phy = devm_kzalloc(dev: &client->dev, size: sizeof(struct microread_i2c_phy), |
240 | GFP_KERNEL); |
241 | if (!phy) |
242 | return -ENOMEM; |
243 | |
244 | i2c_set_clientdata(client, data: phy); |
245 | phy->i2c_dev = client; |
246 | |
247 | r = request_threaded_irq(irq: client->irq, NULL, thread_fn: microread_i2c_irq_thread_fn, |
248 | IRQF_TRIGGER_RISING | IRQF_ONESHOT, |
249 | MICROREAD_I2C_DRIVER_NAME, dev: phy); |
250 | if (r) { |
251 | nfc_err(&client->dev, "Unable to register IRQ handler\n" ); |
252 | return r; |
253 | } |
254 | |
255 | r = microread_probe(phy_id: phy, phy_ops: &i2c_phy_ops, LLC_SHDLC_NAME, |
256 | MICROREAD_I2C_FRAME_HEADROOM, |
257 | MICROREAD_I2C_FRAME_TAILROOM, |
258 | MICROREAD_I2C_LLC_MAX_PAYLOAD, hdev: &phy->hdev); |
259 | if (r < 0) |
260 | goto err_irq; |
261 | |
262 | return 0; |
263 | |
264 | err_irq: |
265 | free_irq(client->irq, phy); |
266 | |
267 | return r; |
268 | } |
269 | |
270 | static void microread_i2c_remove(struct i2c_client *client) |
271 | { |
272 | struct microread_i2c_phy *phy = i2c_get_clientdata(client); |
273 | |
274 | microread_remove(hdev: phy->hdev); |
275 | |
276 | free_irq(client->irq, phy); |
277 | } |
278 | |
279 | static const struct i2c_device_id microread_i2c_id[] = { |
280 | { MICROREAD_I2C_DRIVER_NAME, 0}, |
281 | { } |
282 | }; |
283 | MODULE_DEVICE_TABLE(i2c, microread_i2c_id); |
284 | |
285 | static struct i2c_driver microread_i2c_driver = { |
286 | .driver = { |
287 | .name = MICROREAD_I2C_DRIVER_NAME, |
288 | }, |
289 | .probe = microread_i2c_probe, |
290 | .remove = microread_i2c_remove, |
291 | .id_table = microread_i2c_id, |
292 | }; |
293 | |
294 | module_i2c_driver(microread_i2c_driver); |
295 | |
296 | MODULE_LICENSE("GPL" ); |
297 | MODULE_DESCRIPTION(DRIVER_DESC); |
298 | |