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 const 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); 316