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 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("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 } 105 106 static int microread_i2c_enable(void *phy_id) 107 { 108 return 0; 109 } 110 111 static void microread_i2c_disable(void *phy_id) 112 { 113 return; 114 } 115 116 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 } 149 150 151 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 } 210 211 static irqreturn_t microread_i2c_irq_thread_fn(int irq, void *phy_id) 212 { 213 struct microread_i2c_phy *phy = phy_id; 214 struct i2c_client *client; 215 struct sk_buff *skb = NULL; 216 int r; 217 218 if (!phy || irq != phy->i2c_dev->irq) { 219 WARN_ON_ONCE(1); 220 return IRQ_NONE; 221 } 222 223 client = phy->i2c_dev; 224 225 if (phy->hard_fault != 0) 226 return IRQ_HANDLED; 227 228 r = microread_i2c_read(phy, &skb); 229 if (r == -EREMOTEIO) { 230 phy->hard_fault = r; 231 232 nfc_hci_recv_frame(phy->hdev, NULL); 233 234 return IRQ_HANDLED; 235 } else if ((r == -ENOMEM) || (r == -EBADMSG)) { 236 return IRQ_HANDLED; 237 } 238 239 nfc_hci_recv_frame(phy->hdev, skb); 240 241 return IRQ_HANDLED; 242 } 243 244 static struct nfc_phy_ops i2c_phy_ops = { 245 .write = microread_i2c_write, 246 .enable = microread_i2c_enable, 247 .disable = microread_i2c_disable, 248 }; 249 250 static int microread_i2c_probe(struct i2c_client *client, 251 const struct i2c_device_id *id) 252 { 253 struct microread_i2c_phy *phy; 254 struct microread_nfc_platform_data *pdata = 255 dev_get_platdata(&client->dev); 256 int r; 257 258 dev_dbg(&client->dev, "client %p\n", client); 259 260 if (!pdata) { 261 nfc_err(&client->dev, "client %p: missing platform data\n", 262 client); 263 return -EINVAL; 264 } 265 266 phy = devm_kzalloc(&client->dev, sizeof(struct microread_i2c_phy), 267 GFP_KERNEL); 268 if (!phy) 269 return -ENOMEM; 270 271 i2c_set_clientdata(client, phy); 272 phy->i2c_dev = client; 273 274 r = request_threaded_irq(client->irq, NULL, microread_i2c_irq_thread_fn, 275 IRQF_TRIGGER_RISING | IRQF_ONESHOT, 276 MICROREAD_I2C_DRIVER_NAME, phy); 277 if (r) { 278 nfc_err(&client->dev, "Unable to register IRQ handler\n"); 279 return r; 280 } 281 282 r = microread_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME, 283 MICROREAD_I2C_FRAME_HEADROOM, 284 MICROREAD_I2C_FRAME_TAILROOM, 285 MICROREAD_I2C_LLC_MAX_PAYLOAD, &phy->hdev); 286 if (r < 0) 287 goto err_irq; 288 289 nfc_info(&client->dev, "Probed"); 290 291 return 0; 292 293 err_irq: 294 free_irq(client->irq, phy); 295 296 return r; 297 } 298 299 static int microread_i2c_remove(struct i2c_client *client) 300 { 301 struct microread_i2c_phy *phy = i2c_get_clientdata(client); 302 303 microread_remove(phy->hdev); 304 305 free_irq(client->irq, phy); 306 307 return 0; 308 } 309 310 static struct i2c_device_id microread_i2c_id[] = { 311 { MICROREAD_I2C_DRIVER_NAME, 0}, 312 { } 313 }; 314 MODULE_DEVICE_TABLE(i2c, microread_i2c_id); 315 316 static struct i2c_driver microread_i2c_driver = { 317 .driver = { 318 .name = MICROREAD_I2C_DRIVER_NAME, 319 }, 320 .probe = microread_i2c_probe, 321 .remove = microread_i2c_remove, 322 .id_table = microread_i2c_id, 323 }; 324 325 module_i2c_driver(microread_i2c_driver); 326 327 MODULE_LICENSE("GPL"); 328 MODULE_DESCRIPTION(DRIVER_DESC); 329