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, write to the 17 * Free Software Foundation, Inc., 18 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 19 */ 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 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 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 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(MICROREAD_I2C_DRIVER_NAME 99 ": CRC error 0x%x != 0x%x\n", 100 crc, skb->data[skb->len-1]); 101 102 pr_info(DRIVER_DESC ": %s : BAD CRC\n", __func__); 103 104 return -EPERM; 105 } 106 107 return 0; 108 } 109 110 static int microread_i2c_enable(void *phy_id) 111 { 112 return 0; 113 } 114 115 static void microread_i2c_disable(void *phy_id) 116 { 117 return; 118 } 119 120 static int microread_i2c_write(void *phy_id, struct sk_buff *skb) 121 { 122 int r; 123 struct microread_i2c_phy *phy = phy_id; 124 struct i2c_client *client = phy->i2c_dev; 125 126 if (phy->hard_fault != 0) 127 return phy->hard_fault; 128 129 usleep_range(3000, 6000); 130 131 microread_i2c_add_len_crc(skb); 132 133 I2C_DUMP_SKB("i2c frame written", skb); 134 135 r = i2c_master_send(client, skb->data, skb->len); 136 137 if (r == -EREMOTEIO) { /* Retry, chip was in standby */ 138 usleep_range(6000, 10000); 139 r = i2c_master_send(client, skb->data, skb->len); 140 } 141 142 if (r >= 0) { 143 if (r != skb->len) 144 r = -EREMOTEIO; 145 else 146 r = 0; 147 } 148 149 microread_i2c_remove_len_crc(skb); 150 151 return r; 152 } 153 154 155 static int microread_i2c_read(struct microread_i2c_phy *phy, 156 struct sk_buff **skb) 157 { 158 int r; 159 u8 len; 160 u8 tmp[MICROREAD_I2C_LLC_MAX_SIZE - 1]; 161 struct i2c_client *client = phy->i2c_dev; 162 163 pr_debug("%s\n", __func__); 164 165 r = i2c_master_recv(client, &len, 1); 166 if (r != 1) { 167 dev_err(&client->dev, "cannot read len byte\n"); 168 return -EREMOTEIO; 169 } 170 171 if ((len < MICROREAD_I2C_LLC_MIN_SIZE) || 172 (len > MICROREAD_I2C_LLC_MAX_SIZE)) { 173 dev_err(&client->dev, "invalid len byte\n"); 174 pr_err("invalid len byte\n"); 175 r = -EBADMSG; 176 goto flush; 177 } 178 179 *skb = alloc_skb(1 + len, GFP_KERNEL); 180 if (*skb == NULL) { 181 r = -ENOMEM; 182 goto flush; 183 } 184 185 *skb_put(*skb, 1) = len; 186 187 r = i2c_master_recv(client, skb_put(*skb, len), len); 188 if (r != len) { 189 kfree_skb(*skb); 190 return -EREMOTEIO; 191 } 192 193 I2C_DUMP_SKB("cc frame read", *skb); 194 195 r = check_crc(*skb); 196 if (r != 0) { 197 kfree_skb(*skb); 198 r = -EBADMSG; 199 goto flush; 200 } 201 202 skb_pull(*skb, 1); 203 skb_trim(*skb, (*skb)->len - MICROREAD_I2C_FRAME_TAILROOM); 204 205 usleep_range(3000, 6000); 206 207 return 0; 208 209 flush: 210 if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0) 211 r = -EREMOTEIO; 212 213 usleep_range(3000, 6000); 214 215 return r; 216 } 217 218 static irqreturn_t microread_i2c_irq_thread_fn(int irq, void *phy_id) 219 { 220 struct microread_i2c_phy *phy = phy_id; 221 struct i2c_client *client; 222 struct sk_buff *skb = NULL; 223 int r; 224 225 if (!phy || irq != phy->i2c_dev->irq) { 226 WARN_ON_ONCE(1); 227 return IRQ_NONE; 228 } 229 230 client = phy->i2c_dev; 231 dev_dbg(&client->dev, "IRQ\n"); 232 233 if (phy->hard_fault != 0) 234 return IRQ_HANDLED; 235 236 r = microread_i2c_read(phy, &skb); 237 if (r == -EREMOTEIO) { 238 phy->hard_fault = r; 239 240 nfc_hci_recv_frame(phy->hdev, NULL); 241 242 return IRQ_HANDLED; 243 } else if ((r == -ENOMEM) || (r == -EBADMSG)) { 244 return IRQ_HANDLED; 245 } 246 247 nfc_hci_recv_frame(phy->hdev, skb); 248 249 return IRQ_HANDLED; 250 } 251 252 static struct nfc_phy_ops i2c_phy_ops = { 253 .write = microread_i2c_write, 254 .enable = microread_i2c_enable, 255 .disable = microread_i2c_disable, 256 }; 257 258 static int microread_i2c_probe(struct i2c_client *client, 259 const struct i2c_device_id *id) 260 { 261 struct microread_i2c_phy *phy; 262 struct microread_nfc_platform_data *pdata = 263 dev_get_platdata(&client->dev); 264 int r; 265 266 dev_dbg(&client->dev, "client %p", client); 267 268 if (!pdata) { 269 dev_err(&client->dev, "client %p: missing platform data", 270 client); 271 return -EINVAL; 272 } 273 274 phy = devm_kzalloc(&client->dev, sizeof(struct microread_i2c_phy), 275 GFP_KERNEL); 276 if (!phy) { 277 dev_err(&client->dev, "Can't allocate microread phy"); 278 return -ENOMEM; 279 } 280 281 i2c_set_clientdata(client, phy); 282 phy->i2c_dev = client; 283 284 r = request_threaded_irq(client->irq, NULL, microread_i2c_irq_thread_fn, 285 IRQF_TRIGGER_RISING | IRQF_ONESHOT, 286 MICROREAD_I2C_DRIVER_NAME, phy); 287 if (r) { 288 dev_err(&client->dev, "Unable to register IRQ handler"); 289 return r; 290 } 291 292 r = microread_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME, 293 MICROREAD_I2C_FRAME_HEADROOM, 294 MICROREAD_I2C_FRAME_TAILROOM, 295 MICROREAD_I2C_LLC_MAX_PAYLOAD, &phy->hdev); 296 if (r < 0) 297 goto err_irq; 298 299 dev_info(&client->dev, "Probed"); 300 301 return 0; 302 303 err_irq: 304 free_irq(client->irq, phy); 305 306 return r; 307 } 308 309 static int microread_i2c_remove(struct i2c_client *client) 310 { 311 struct microread_i2c_phy *phy = i2c_get_clientdata(client); 312 313 dev_dbg(&client->dev, "%s\n", __func__); 314 315 microread_remove(phy->hdev); 316 317 free_irq(client->irq, phy); 318 319 return 0; 320 } 321 322 static struct i2c_device_id microread_i2c_id[] = { 323 { MICROREAD_I2C_DRIVER_NAME, 0}, 324 { } 325 }; 326 MODULE_DEVICE_TABLE(i2c, microread_i2c_id); 327 328 static struct i2c_driver microread_i2c_driver = { 329 .driver = { 330 .name = MICROREAD_I2C_DRIVER_NAME, 331 }, 332 .probe = microread_i2c_probe, 333 .remove = microread_i2c_remove, 334 .id_table = microread_i2c_id, 335 }; 336 337 module_i2c_driver(microread_i2c_driver); 338 339 MODULE_LICENSE("GPL"); 340 MODULE_DESCRIPTION(DRIVER_DESC); 341