drivers/nfc/st21nfcb/i2c.c

   1 /*
   2  * I2C Link Layer for ST21NFCB NCI based Driver
   3  * Copyright (C) 2014  STMicroelectronics SAS. All rights reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms and conditions of the GNU General Public License,
   7  * version 2, as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  19
  20 #include <linux/module.h>
  21 #include <linux/i2c.h>
  22 #include <linux/gpio.h>
  23 #include <linux/of_irq.h>
  24 #include <linux/of_gpio.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/delay.h>
  27 #include <linux/nfc.h>
  28 #include <linux/platform_data/st21nfcb.h>
  29
  30 #include "ndlc.h"
  31
  32 #define DRIVER_DESC "NCI NFC driver for ST21NFCB"
  33
  34 /* ndlc header */
  35 #define ST21NFCB_FRAME_HEADROOM 1
  36 #define ST21NFCB_FRAME_TAILROOM 0
  37
  38 #define ST21NFCB_NCI_I2C_MIN_SIZE 4   /* PCB(1) + NCI Packet header(3) */
  39 #define ST21NFCB_NCI_I2C_MAX_SIZE 250 /* req 4.2.1 */
  40
  41 #define ST21NFCB_NCI_I2C_DRIVER_NAME "st21nfcb_nci_i2c"
  42
  43 static struct i2c_device_id st21nfcb_nci_i2c_id_table[] = {
  44         {ST21NFCB_NCI_DRIVER_NAME, 0},
  45         {}
  46 };
  47 MODULE_DEVICE_TABLE(i2c, st21nfcb_nci_i2c_id_table);
  48
  49 struct st21nfcb_i2c_phy {
  50         struct i2c_client *i2c_dev;
  51         struct llt_ndlc *ndlc;
  52
  53         unsigned int gpio_reset;
  54         unsigned int irq_polarity;
  55
  56         int powered;
  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 int st21nfcb_nci_i2c_enable(void *phy_id)
  67 {
  68         struct st21nfcb_i2c_phy *phy = phy_id;
  69
  70         gpio_set_value(phy->gpio_reset, 0);
  71         usleep_range(10000, 15000);
  72         gpio_set_value(phy->gpio_reset, 1);
  73         phy->powered = 1;
  74         usleep_range(80000, 85000);
  75
  76         return 0;
  77 }
  78
  79 static void st21nfcb_nci_i2c_disable(void *phy_id)
  80 {
  81         struct st21nfcb_i2c_phy *phy = phy_id;
  82
  83         phy->powered = 0;
  84         /* reset chip in order to flush clf */
  85         gpio_set_value(phy->gpio_reset, 0);
  86         usleep_range(10000, 15000);
  87         gpio_set_value(phy->gpio_reset, 1);
  88 }
  89
  90 static void st21nfcb_nci_remove_header(struct sk_buff *skb)
  91 {
  92         skb_pull(skb, ST21NFCB_FRAME_HEADROOM);
  93 }
  94
  95 /*
  96  * Writing a frame must not return the number of written bytes.
  97  * It must return either zero for success, or <0 for error.
  98  * In addition, it must not alter the skb
  99  */
 100 static int st21nfcb_nci_i2c_write(void *phy_id, struct sk_buff *skb)
 101 {
 102         int r = -1;
 103         struct st21nfcb_i2c_phy *phy = phy_id;
 104         struct i2c_client *client = phy->i2c_dev;
 105
 106         I2C_DUMP_SKB("st21nfcb_nci_i2c_write", skb);
 107
 108         if (phy->ndlc->hard_fault != 0)
 109                 return phy->ndlc->hard_fault;
 110
 111         r = i2c_master_send(client, skb->data, skb->len);
 112         if (r == -EREMOTEIO) {  /* Retry, chip was in standby */
 113                 usleep_range(1000, 4000);
 114                 r = i2c_master_send(client, skb->data, skb->len);
 115         }
 116
 117         if (r >= 0) {
 118                 if (r != skb->len)
 119                         r = -EREMOTEIO;
 120                 else
 121                         r = 0;
 122         }
 123
 124         st21nfcb_nci_remove_header(skb);
 125
 126         return r;
 127 }
 128
 129 /*
 130  * Reads an ndlc frame and returns it in a newly allocated sk_buff.
 131  * returns:
 132  * frame size : if received frame is complete (find ST21NFCB_SOF_EOF at
 133  * end of read)
 134  * -EAGAIN : if received frame is incomplete (not find ST21NFCB_SOF_EOF
 135  * at end of read)
 136  * -EREMOTEIO : i2c read error (fatal)
 137  * -EBADMSG : frame was incorrect and discarded
 138  * (value returned from st21nfcb_nci_i2c_repack)
 139  * -EIO : if no ST21NFCB_SOF_EOF is found after reaching
 140  * the read length end sequence
 141  */
 142 static int st21nfcb_nci_i2c_read(struct st21nfcb_i2c_phy *phy,
 143                                  struct sk_buff **skb)
 144 {
 145         int r;
 146         u8 len;
 147         u8 buf[ST21NFCB_NCI_I2C_MAX_SIZE];
 148         struct i2c_client *client = phy->i2c_dev;
 149
 150         r = i2c_master_recv(client, buf, ST21NFCB_NCI_I2C_MIN_SIZE);
 151         if (r == -EREMOTEIO) {  /* Retry, chip was in standby */
 152                 usleep_range(1000, 4000);
 153                 r = i2c_master_recv(client, buf, ST21NFCB_NCI_I2C_MIN_SIZE);
 154         }
 155
 156         if (r != ST21NFCB_NCI_I2C_MIN_SIZE)
 157                 return -EREMOTEIO;
 158
 159         len = be16_to_cpu(*(__be16 *) (buf + 2));
 160         if (len > ST21NFCB_NCI_I2C_MAX_SIZE) {
 161                 nfc_err(&client->dev, "invalid frame len\n");
 162                 return -EBADMSG;
 163         }
 164
 165         *skb = alloc_skb(ST21NFCB_NCI_I2C_MIN_SIZE + len, GFP_KERNEL);
 166         if (*skb == NULL)
 167                 return -ENOMEM;
 168
 169         skb_reserve(*skb, ST21NFCB_NCI_I2C_MIN_SIZE);
 170         skb_put(*skb, ST21NFCB_NCI_I2C_MIN_SIZE);
 171         memcpy((*skb)->data, buf, ST21NFCB_NCI_I2C_MIN_SIZE);
 172
 173         if (!len)
 174                 return 0;
 175
 176         r = i2c_master_recv(client, buf, len);
 177         if (r != len) {
 178                 kfree_skb(*skb);
 179                 return -EREMOTEIO;
 180         }
 181
 182         skb_put(*skb, len);
 183         memcpy((*skb)->data + ST21NFCB_NCI_I2C_MIN_SIZE, buf, len);
 184
 185         I2C_DUMP_SKB("i2c frame read", *skb);
 186
 187         return 0;
 188 }
 189
 190 /*
 191  * Reads an ndlc frame from the chip.
 192  *
 193  * On ST21NFCB, IRQ goes in idle state when read starts.
 194  */
 195 static irqreturn_t st21nfcb_nci_irq_thread_fn(int irq, void *phy_id)
 196 {
 197         struct st21nfcb_i2c_phy *phy = phy_id;
 198         struct i2c_client *client;
 199         struct sk_buff *skb = NULL;
 200         int r;
 201
 202         if (!phy || irq != phy->i2c_dev->irq) {
 203                 WARN_ON_ONCE(1);
 204                 return IRQ_NONE;
 205         }
 206
 207         client = phy->i2c_dev;
 208         dev_dbg(&client->dev, "IRQ\n");
 209
 210         if (phy->ndlc->hard_fault)
 211                 return IRQ_HANDLED;
 212
 213         if (!phy->powered) {
 214                 st21nfcb_nci_i2c_disable(phy);
 215                 return IRQ_HANDLED;
 216         }
 217
 218         r = st21nfcb_nci_i2c_read(phy, &skb);
 219         if (r == -EREMOTEIO || r == -ENOMEM || r == -EBADMSG)
 220                 return IRQ_HANDLED;
 221
 222         ndlc_recv(phy->ndlc, skb);
 223
 224         return IRQ_HANDLED;
 225 }
 226
 227 static struct nfc_phy_ops i2c_phy_ops = {
 228         .write = st21nfcb_nci_i2c_write,
 229         .enable = st21nfcb_nci_i2c_enable,
 230         .disable = st21nfcb_nci_i2c_disable,
 231 };
 232
 233 #ifdef CONFIG_OF
 234 static int st21nfcb_nci_i2c_of_request_resources(struct i2c_client *client)
 235 {
 236         struct st21nfcb_i2c_phy *phy = i2c_get_clientdata(client);
 237         struct device_node *pp;
 238         int gpio;
 239         int r;
 240
 241         pp = client->dev.of_node;
 242         if (!pp)
 243                 return -ENODEV;
 244
 245         /* Get GPIO from device tree */
 246         gpio = of_get_named_gpio(pp, "reset-gpios", 0);
 247         if (gpio < 0) {
 248                 nfc_err(&client->dev,
 249                         "Failed to retrieve reset-gpios from device tree\n");
 250                 return gpio;
 251         }
 252
 253         /* GPIO request and configuration */
 254         r = devm_gpio_request_one(&client->dev, gpio,
 255                                 GPIOF_OUT_INIT_HIGH, "clf_reset");
 256         if (r) {
 257                 nfc_err(&client->dev, "Failed to request reset pin\n");
 258                 return r;
 259         }
 260         phy->gpio_reset = gpio;
 261
 262         phy->irq_polarity = irq_get_trigger_type(client->irq);
 263
 264         return 0;
 265 }
 266 #else
 267 static int st21nfcb_nci_i2c_of_request_resources(struct i2c_client *client)
 268 {
 269         return -ENODEV;
 270 }
 271 #endif
 272
 273 static int st21nfcb_nci_i2c_request_resources(struct i2c_client *client)
 274 {
 275         struct st21nfcb_nfc_platform_data *pdata;
 276         struct st21nfcb_i2c_phy *phy = i2c_get_clientdata(client);
 277         int r;
 278
 279         pdata = client->dev.platform_data;
 280         if (pdata == NULL) {
 281                 nfc_err(&client->dev, "No platform data\n");
 282                 return -EINVAL;
 283         }
 284
 285         /* store for later use */
 286         phy->gpio_reset = pdata->gpio_reset;
 287         phy->irq_polarity = pdata->irq_polarity;
 288
 289         r = devm_gpio_request_one(&client->dev,
 290                         phy->gpio_reset, GPIOF_OUT_INIT_HIGH, "clf_reset");
 291         if (r) {
 292                 pr_err("%s : reset gpio_request failed\n", __FILE__);
 293                 return r;
 294         }
 295
 296         return 0;
 297 }
 298
 299 static int st21nfcb_nci_i2c_probe(struct i2c_client *client,
 300                                   const struct i2c_device_id *id)
 301 {
 302         struct st21nfcb_i2c_phy *phy;
 303         struct st21nfcb_nfc_platform_data *pdata;
 304         int r;
 305
 306         dev_dbg(&client->dev, "%s\n", __func__);
 307         dev_dbg(&client->dev, "IRQ: %d\n", client->irq);
 308
 309         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
 310                 nfc_err(&client->dev, "Need I2C_FUNC_I2C\n");
 311                 return -ENODEV;
 312         }
 313
 314         phy = devm_kzalloc(&client->dev, sizeof(struct st21nfcb_i2c_phy),
 315                            GFP_KERNEL);
 316         if (!phy) {
 317                 nfc_err(&client->dev,
 318                         "Cannot allocate memory for st21nfcb i2c phy.\n");
 319                 return -ENOMEM;
 320         }
 321
 322         phy->i2c_dev = client;
 323
 324         i2c_set_clientdata(client, phy);
 325
 326         pdata = client->dev.platform_data;
 327         if (!pdata && client->dev.of_node) {
 328                 r = st21nfcb_nci_i2c_of_request_resources(client);
 329                 if (r) {
 330                         nfc_err(&client->dev, "No platform data\n");
 331                         return r;
 332                 }
 333         } else if (pdata) {
 334                 r = st21nfcb_nci_i2c_request_resources(client);
 335                 if (r) {
 336                         nfc_err(&client->dev,
 337                                 "Cannot get platform resources\n");
 338                         return r;
 339                 }
 340         } else {
 341                 nfc_err(&client->dev,
 342                         "st21nfcb platform resources not available\n");
 343                 return -ENODEV;
 344         }
 345
 346         r = devm_request_threaded_irq(&client->dev, client->irq, NULL,
 347                                 st21nfcb_nci_irq_thread_fn,
 348                                 phy->irq_polarity | IRQF_ONESHOT,
 349                                 ST21NFCB_NCI_DRIVER_NAME, phy);
 350         if (r < 0) {
 351                 nfc_err(&client->dev, "Unable to register IRQ handler\n");
 352                 return r;
 353         }
 354
 355         return ndlc_probe(phy, &i2c_phy_ops, &client->dev,
 356                         ST21NFCB_FRAME_HEADROOM, ST21NFCB_FRAME_TAILROOM,
 357                         &phy->ndlc);
 358 }
 359
 360 static int st21nfcb_nci_i2c_remove(struct i2c_client *client)
 361 {
 362         struct st21nfcb_i2c_phy *phy = i2c_get_clientdata(client);
 363
 364         dev_dbg(&client->dev, "%s\n", __func__);
 365
 366         ndlc_remove(phy->ndlc);
 367
 368         if (phy->powered)
 369                 st21nfcb_nci_i2c_disable(phy);
 370
 371         return 0;
 372 }
 373
 374 #ifdef CONFIG_OF
 375 static const struct of_device_id of_st21nfcb_i2c_match[] = {
 376         { .compatible = "st,st21nfcb_i2c", },
 377         {}
 378 };
 379 MODULE_DEVICE_TABLE(of, of_st21nfcb_i2c_match);
 380 #endif
 381
 382 static struct i2c_driver st21nfcb_nci_i2c_driver = {
 383         .driver = {
 384                 .owner = THIS_MODULE,
 385                 .name = ST21NFCB_NCI_I2C_DRIVER_NAME,
 386                 .of_match_table = of_match_ptr(of_st21nfcb_i2c_match),
 387         },
 388         .probe = st21nfcb_nci_i2c_probe,
 389         .id_table = st21nfcb_nci_i2c_id_table,
 390         .remove = st21nfcb_nci_i2c_remove,
 391 };
 392
 393 module_i2c_driver(st21nfcb_nci_i2c_driver);
 394
 395 MODULE_LICENSE("GPL");
 396 MODULE_DESCRIPTION(DRIVER_DESC);