kernel/drivers/nfc/microread/i2c.c

   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\n");
 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);