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, 1) = len; 63 64 for (i = 0; i < skb->len; i++) 65 crc = crc ^ skb->data[i]; 66 67 skb_put_u8(skb, 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(3000, 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, skb->data, skb->len); 119 120 if (r == -EREMOTEIO) { /* Retry, chip was in standby */ 121 usleep_range(6000, 10000); 122 r = i2c_master_send(client, skb->data, 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, &len, 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(1 + len, GFP_KERNEL); 160 if (*skb == NULL) { 161 r = -ENOMEM; 162 goto flush; 163 } 164 165 skb_put_u8(*skb, len); 166 167 r = i2c_master_recv(client, skb_put(*skb, len), len); 168 if (r != len) { 169 kfree_skb(*skb); 170 return -EREMOTEIO; 171 } 172 173 I2C_DUMP_SKB("cc frame read", *skb); 174 175 r = check_crc(*skb); 176 if (r != 0) { 177 kfree_skb(*skb); 178 r = -EBADMSG; 179 goto flush; 180 } 181 182 skb_pull(*skb, 1); 183 skb_trim(*skb, (*skb)->len - MICROREAD_I2C_FRAME_TAILROOM); 184 185 usleep_range(3000, 6000); 186 187 return 0; 188 189 flush: 190 if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0) 191 r = -EREMOTEIO; 192 193 usleep_range(3000, 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); 213 if (r == -EREMOTEIO) { 214 phy->hard_fault = r; 215 216 nfc_hci_recv_frame(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(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(&client->dev, sizeof(struct microread_i2c_phy), 240 GFP_KERNEL); 241 if (!phy) 242 return -ENOMEM; 243 244 i2c_set_clientdata(client, phy); 245 phy->i2c_dev = client; 246 247 r = request_threaded_irq(client->irq, NULL, microread_i2c_irq_thread_fn, 248 IRQF_TRIGGER_RISING | IRQF_ONESHOT, 249 MICROREAD_I2C_DRIVER_NAME, 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, &i2c_phy_ops, LLC_SHDLC_NAME, 256 MICROREAD_I2C_FRAME_HEADROOM, 257 MICROREAD_I2C_FRAME_TAILROOM, 258 MICROREAD_I2C_LLC_MAX_PAYLOAD, &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(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_new = 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