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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 22 23 #include <linux/module.h> 24 #include <linux/i2c.h> 25 #include <linux/delay.h> 26 #include <linux/slab.h> 27 #include <linux/interrupt.h> 28 #include <linux/gpio.h> 29 30 #include <linux/nfc.h> 31 #include <net/nfc/hci.h> 32 #include <net/nfc/llc.h> 33 34 #include "microread.h" 35 36 #define MICROREAD_I2C_DRIVER_NAME "microread" 37 38 #define MICROREAD_I2C_FRAME_HEADROOM 1 39 #define MICROREAD_I2C_FRAME_TAILROOM 1 40 41 /* framing in HCI mode */ 42 #define MICROREAD_I2C_LLC_LEN 1 43 #define MICROREAD_I2C_LLC_CRC 1 44 #define MICROREAD_I2C_LLC_LEN_CRC (MICROREAD_I2C_LLC_LEN + \ 45 MICROREAD_I2C_LLC_CRC) 46 #define MICROREAD_I2C_LLC_MIN_SIZE (1 + MICROREAD_I2C_LLC_LEN_CRC) 47 #define MICROREAD_I2C_LLC_MAX_PAYLOAD 29 48 #define MICROREAD_I2C_LLC_MAX_SIZE (MICROREAD_I2C_LLC_LEN_CRC + 1 + \ 49 MICROREAD_I2C_LLC_MAX_PAYLOAD) 50 51 struct microread_i2c_phy { 52 struct i2c_client *i2c_dev; 53 struct nfc_hci_dev *hdev; 54 55 int irq; 56 57 int hard_fault; /* 58 * < 0 if hardware error occured (e.g. i2c err) 59 * and prevents normal operation. 60 */ 61 }; 62 63 #define I2C_DUMP_SKB(info, skb) \ 64 do { \ 65 pr_debug("%s:\n", info); \ 66 print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET, \ 67 16, 1, (skb)->data, (skb)->len, 0); \ 68 } while (0) 69 70 static void microread_i2c_add_len_crc(struct sk_buff *skb) 71 { 72 int i; 73 u8 crc = 0; 74 int len; 75 76 len = skb->len; 77 *skb_push(skb, 1) = len; 78 79 for (i = 0; i < skb->len; i++) 80 crc = crc ^ skb->data[i]; 81 82 *skb_put(skb, 1) = crc; 83 } 84 85 static void microread_i2c_remove_len_crc(struct sk_buff *skb) 86 { 87 skb_pull(skb, MICROREAD_I2C_FRAME_HEADROOM); 88 skb_trim(skb, MICROREAD_I2C_FRAME_TAILROOM); 89 } 90 91 static int check_crc(struct sk_buff *skb) 92 { 93 int i; 94 u8 crc = 0; 95 96 for (i = 0; i < skb->len - 1; i++) 97 crc = crc ^ skb->data[i]; 98 99 if (crc != skb->data[skb->len-1]) { 100 pr_err("CRC error 0x%x != 0x%x\n", crc, skb->data[skb->len-1]); 101 pr_info("%s: BAD CRC\n", __func__); 102 return -EPERM; 103 } 104 105 return 0; 106 } 107 108 static int microread_i2c_enable(void *phy_id) 109 { 110 return 0; 111 } 112 113 static void microread_i2c_disable(void *phy_id) 114 { 115 return; 116 } 117 118 static int microread_i2c_write(void *phy_id, struct sk_buff *skb) 119 { 120 int r; 121 struct microread_i2c_phy *phy = phy_id; 122 struct i2c_client *client = phy->i2c_dev; 123 124 if (phy->hard_fault != 0) 125 return phy->hard_fault; 126 127 usleep_range(3000, 6000); 128 129 microread_i2c_add_len_crc(skb); 130 131 I2C_DUMP_SKB("i2c frame written", skb); 132 133 r = i2c_master_send(client, skb->data, skb->len); 134 135 if (r == -EREMOTEIO) { /* Retry, chip was in standby */ 136 usleep_range(6000, 10000); 137 r = i2c_master_send(client, skb->data, skb->len); 138 } 139 140 if (r >= 0) { 141 if (r != skb->len) 142 r = -EREMOTEIO; 143 else 144 r = 0; 145 } 146 147 microread_i2c_remove_len_crc(skb); 148 149 return r; 150 } 151 152 153 static int microread_i2c_read(struct microread_i2c_phy *phy, 154 struct sk_buff **skb) 155 { 156 int r; 157 u8 len; 158 u8 tmp[MICROREAD_I2C_LLC_MAX_SIZE - 1]; 159 struct i2c_client *client = phy->i2c_dev; 160 161 r = i2c_master_recv(client, &len, 1); 162 if (r != 1) { 163 nfc_err(&client->dev, "cannot read len byte\n"); 164 return -EREMOTEIO; 165 } 166 167 if ((len < MICROREAD_I2C_LLC_MIN_SIZE) || 168 (len > MICROREAD_I2C_LLC_MAX_SIZE)) { 169 nfc_err(&client->dev, "invalid len byte\n"); 170 r = -EBADMSG; 171 goto flush; 172 } 173 174 *skb = alloc_skb(1 + len, GFP_KERNEL); 175 if (*skb == NULL) { 176 r = -ENOMEM; 177 goto flush; 178 } 179 180 *skb_put(*skb, 1) = len; 181 182 r = i2c_master_recv(client, skb_put(*skb, len), len); 183 if (r != len) { 184 kfree_skb(*skb); 185 return -EREMOTEIO; 186 } 187 188 I2C_DUMP_SKB("cc frame read", *skb); 189 190 r = check_crc(*skb); 191 if (r != 0) { 192 kfree_skb(*skb); 193 r = -EBADMSG; 194 goto flush; 195 } 196 197 skb_pull(*skb, 1); 198 skb_trim(*skb, (*skb)->len - MICROREAD_I2C_FRAME_TAILROOM); 199 200 usleep_range(3000, 6000); 201 202 return 0; 203 204 flush: 205 if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0) 206 r = -EREMOTEIO; 207 208 usleep_range(3000, 6000); 209 210 return r; 211 } 212 213 static irqreturn_t microread_i2c_irq_thread_fn(int irq, void *phy_id) 214 { 215 struct microread_i2c_phy *phy = phy_id; 216 struct i2c_client *client; 217 struct sk_buff *skb = NULL; 218 int r; 219 220 if (!phy || irq != phy->i2c_dev->irq) { 221 WARN_ON_ONCE(1); 222 return IRQ_NONE; 223 } 224 225 client = phy->i2c_dev; 226 227 if (phy->hard_fault != 0) 228 return IRQ_HANDLED; 229 230 r = microread_i2c_read(phy, &skb); 231 if (r == -EREMOTEIO) { 232 phy->hard_fault = r; 233 234 nfc_hci_recv_frame(phy->hdev, NULL); 235 236 return IRQ_HANDLED; 237 } else if ((r == -ENOMEM) || (r == -EBADMSG)) { 238 return IRQ_HANDLED; 239 } 240 241 nfc_hci_recv_frame(phy->hdev, skb); 242 243 return IRQ_HANDLED; 244 } 245 246 static struct nfc_phy_ops i2c_phy_ops = { 247 .write = microread_i2c_write, 248 .enable = microread_i2c_enable, 249 .disable = microread_i2c_disable, 250 }; 251 252 static int microread_i2c_probe(struct i2c_client *client, 253 const struct i2c_device_id *id) 254 { 255 struct microread_i2c_phy *phy; 256 struct microread_nfc_platform_data *pdata = 257 dev_get_platdata(&client->dev); 258 int r; 259 260 dev_dbg(&client->dev, "client %p\n", client); 261 262 if (!pdata) { 263 nfc_err(&client->dev, "client %p: missing platform data\n", 264 client); 265 return -EINVAL; 266 } 267 268 phy = devm_kzalloc(&client->dev, sizeof(struct microread_i2c_phy), 269 GFP_KERNEL); 270 if (!phy) 271 return -ENOMEM; 272 273 i2c_set_clientdata(client, phy); 274 phy->i2c_dev = client; 275 276 r = request_threaded_irq(client->irq, NULL, microread_i2c_irq_thread_fn, 277 IRQF_TRIGGER_RISING | IRQF_ONESHOT, 278 MICROREAD_I2C_DRIVER_NAME, phy); 279 if (r) { 280 nfc_err(&client->dev, "Unable to register IRQ handler\n"); 281 return r; 282 } 283 284 r = microread_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME, 285 MICROREAD_I2C_FRAME_HEADROOM, 286 MICROREAD_I2C_FRAME_TAILROOM, 287 MICROREAD_I2C_LLC_MAX_PAYLOAD, &phy->hdev); 288 if (r < 0) 289 goto err_irq; 290 291 nfc_info(&client->dev, "Probed"); 292 293 return 0; 294 295 err_irq: 296 free_irq(client->irq, phy); 297 298 return r; 299 } 300 301 static int microread_i2c_remove(struct i2c_client *client) 302 { 303 struct microread_i2c_phy *phy = i2c_get_clientdata(client); 304 305 microread_remove(phy->hdev); 306 307 free_irq(client->irq, phy); 308 309 return 0; 310 } 311 312 static struct i2c_device_id microread_i2c_id[] = { 313 { MICROREAD_I2C_DRIVER_NAME, 0}, 314 { } 315 }; 316 MODULE_DEVICE_TABLE(i2c, microread_i2c_id); 317 318 static struct i2c_driver microread_i2c_driver = { 319 .driver = { 320 .name = MICROREAD_I2C_DRIVER_NAME, 321 }, 322 .probe = microread_i2c_probe, 323 .remove = microread_i2c_remove, 324 .id_table = microread_i2c_id, 325 }; 326 327 module_i2c_driver(microread_i2c_driver); 328 329 MODULE_LICENSE("GPL"); 330 MODULE_DESCRIPTION(DRIVER_DESC); 331