NFC: microread: Add i2c physical layer
authorSamuel Ortiz <sameo@linux.intel.com>
Tue, 18 Dec 2012 13:56:15 +0000 (14:56 +0100)
committerSamuel Ortiz <sameo@linux.intel.com>
Sun, 3 Feb 2013 19:37:48 +0000 (20:37 +0100)
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
drivers/nfc/microread/Kconfig
drivers/nfc/microread/Makefile
drivers/nfc/microread/i2c.c [new file with mode: 0644]

index 5b89d011d0986d7465de45a49a99e9ef02f5294d..cd6744bc8db62b03989fdbf34a6b95793e2af64a 100644 (file)
@@ -11,3 +11,14 @@ config NFC_MICROREAD
          To compile this driver as a module, choose m here. The module will
          be called microread.
          Say N if unsure.
+
+config NFC_MICROREAD_I2C
+       tristate "NFC Microread i2c support"
+       depends on NFC_MICROREAD && I2C && NFC_SHDLC
+       ---help---
+         This module adds support for the i2c interface of adapters using
+         Inside microread chipsets.  Select this if your platform is using
+         the i2c bus.
+
+         If you choose to build a module, it'll be called microread_i2c.
+         Say N if unsure.
index 9ce2c53f49a77cb29bdd77444d23850d656d5d95..74c185165ebfb87a01715366dc6ad077b59f1424 100644 (file)
@@ -2,4 +2,7 @@
 # Makefile for Microread HCI based NFC driver
 #
 
+microread_i2c-objs  = i2c.o
+
 obj-$(CONFIG_NFC_MICROREAD)     += microread.o
+obj-$(CONFIG_NFC_MICROREAD_I2C) += microread_i2c.o
diff --git a/drivers/nfc/microread/i2c.c b/drivers/nfc/microread/i2c.c
new file mode 100644 (file)
index 0000000..1010894
--- /dev/null
@@ -0,0 +1,340 @@
+/*
+ * HCI based Driver for Inside Secure microread NFC Chip - i2c layer
+ *
+ * Copyright (C) 2013 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the
+ * Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/gpio.h>
+
+#include <linux/nfc.h>
+#include <net/nfc/hci.h>
+#include <net/nfc/llc.h>
+
+#include "microread.h"
+
+#define MICROREAD_I2C_DRIVER_NAME "microread"
+
+#define MICROREAD_I2C_FRAME_HEADROOM 1
+#define MICROREAD_I2C_FRAME_TAILROOM 1
+
+/* framing in HCI mode */
+#define MICROREAD_I2C_LLC_LEN          1
+#define MICROREAD_I2C_LLC_CRC          1
+#define MICROREAD_I2C_LLC_LEN_CRC      (MICROREAD_I2C_LLC_LEN + \
+                                       MICROREAD_I2C_LLC_CRC)
+#define MICROREAD_I2C_LLC_MIN_SIZE     (1 + MICROREAD_I2C_LLC_LEN_CRC)
+#define MICROREAD_I2C_LLC_MAX_PAYLOAD  29
+#define MICROREAD_I2C_LLC_MAX_SIZE     (MICROREAD_I2C_LLC_LEN_CRC + 1 + \
+                                       MICROREAD_I2C_LLC_MAX_PAYLOAD)
+
+struct microread_i2c_phy {
+       struct i2c_client *i2c_dev;
+       struct nfc_hci_dev *hdev;
+
+       int irq;
+
+       int hard_fault;         /*
+                                * < 0 if hardware error occured (e.g. i2c err)
+                                * and prevents normal operation.
+                                */
+};
+
+#define I2C_DUMP_SKB(info, skb)                                        \
+do {                                                           \
+       pr_debug("%s:\n", info);                                \
+       print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET, \
+                      16, 1, (skb)->data, (skb)->len, 0);      \
+} while (0)
+
+static void microread_i2c_add_len_crc(struct sk_buff *skb)
+{
+       int i;
+       u8 crc = 0;
+       int len;
+
+       len = skb->len;
+       *skb_push(skb, 1) = len;
+
+       for (i = 0; i < skb->len; i++)
+               crc = crc ^ skb->data[i];
+
+       *skb_put(skb, 1) = crc;
+}
+
+static void microread_i2c_remove_len_crc(struct sk_buff *skb)
+{
+       skb_pull(skb, MICROREAD_I2C_FRAME_HEADROOM);
+       skb_trim(skb, MICROREAD_I2C_FRAME_TAILROOM);
+}
+
+static int check_crc(struct sk_buff *skb)
+{
+       int i;
+       u8 crc = 0;
+
+       for (i = 0; i < skb->len - 1; i++)
+               crc = crc ^ skb->data[i];
+
+       if (crc != skb->data[skb->len-1]) {
+               pr_err(MICROREAD_I2C_DRIVER_NAME
+                      ": CRC error 0x%x != 0x%x\n",
+                      crc, skb->data[skb->len-1]);
+
+               pr_info(DRIVER_DESC ": %s : BAD CRC\n", __func__);
+
+               return -EPERM;
+       }
+
+       return 0;
+}
+
+static int microread_i2c_enable(void *phy_id)
+{
+       return 0;
+}
+
+static void microread_i2c_disable(void *phy_id)
+{
+       return;
+}
+
+static int microread_i2c_write(void *phy_id, struct sk_buff *skb)
+{
+       int r;
+       struct microread_i2c_phy *phy = phy_id;
+       struct i2c_client *client = phy->i2c_dev;
+
+       if (phy->hard_fault != 0)
+               return phy->hard_fault;
+
+       usleep_range(3000, 6000);
+
+       microread_i2c_add_len_crc(skb);
+
+       I2C_DUMP_SKB("i2c frame written", skb);
+
+       r = i2c_master_send(client, skb->data, skb->len);
+
+       if (r == -EREMOTEIO) {  /* Retry, chip was in standby */
+               usleep_range(6000, 10000);
+               r = i2c_master_send(client, skb->data, skb->len);
+       }
+
+       if (r >= 0) {
+               if (r != skb->len)
+                       r = -EREMOTEIO;
+               else
+                       r = 0;
+       }
+
+       microread_i2c_remove_len_crc(skb);
+
+       return r;
+}
+
+
+static int microread_i2c_read(struct microread_i2c_phy *phy,
+                             struct sk_buff **skb)
+{
+       int r;
+       u8 len;
+       u8 tmp[MICROREAD_I2C_LLC_MAX_SIZE - 1];
+       struct i2c_client *client = phy->i2c_dev;
+
+       pr_debug("%s\n", __func__);
+
+       r = i2c_master_recv(client, &len, 1);
+       if (r != 1) {
+               dev_err(&client->dev, "cannot read len byte\n");
+               return -EREMOTEIO;
+       }
+
+       if ((len < MICROREAD_I2C_LLC_MIN_SIZE) ||
+           (len > MICROREAD_I2C_LLC_MAX_SIZE)) {
+               dev_err(&client->dev, "invalid len byte\n");
+               pr_err("invalid len byte\n");
+               r = -EBADMSG;
+               goto flush;
+       }
+
+       *skb = alloc_skb(1 + len, GFP_KERNEL);
+       if (*skb == NULL) {
+               r = -ENOMEM;
+               goto flush;
+       }
+
+       *skb_put(*skb, 1) = len;
+
+       r = i2c_master_recv(client, skb_put(*skb, len), len);
+       if (r != len) {
+               kfree_skb(*skb);
+               return -EREMOTEIO;
+       }
+
+       I2C_DUMP_SKB("cc frame read", *skb);
+
+       r = check_crc(*skb);
+       if (r != 0) {
+               kfree_skb(*skb);
+               r = -EBADMSG;
+               goto flush;
+       }
+
+       skb_pull(*skb, 1);
+       skb_trim(*skb, (*skb)->len - MICROREAD_I2C_FRAME_TAILROOM);
+
+       usleep_range(3000, 6000);
+
+       return 0;
+
+flush:
+       if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0)
+               r = -EREMOTEIO;
+
+       usleep_range(3000, 6000);
+
+       return r;
+}
+
+static irqreturn_t microread_i2c_irq_thread_fn(int irq, void *phy_id)
+{
+       struct microread_i2c_phy *phy = phy_id;
+       struct i2c_client *client;
+       struct sk_buff *skb = NULL;
+       int r;
+
+       if (!phy || irq != phy->i2c_dev->irq) {
+               WARN_ON_ONCE(1);
+               return IRQ_NONE;
+       }
+
+       client = phy->i2c_dev;
+       dev_dbg(&client->dev, "IRQ\n");
+
+       if (phy->hard_fault != 0)
+               return IRQ_HANDLED;
+
+       r = microread_i2c_read(phy, &skb);
+       if (r == -EREMOTEIO) {
+               phy->hard_fault = r;
+
+               nfc_hci_recv_frame(phy->hdev, NULL);
+
+               return IRQ_HANDLED;
+       } else if ((r == -ENOMEM) || (r == -EBADMSG)) {
+               return IRQ_HANDLED;
+       }
+
+       nfc_hci_recv_frame(phy->hdev, skb);
+
+       return IRQ_HANDLED;
+}
+
+static struct nfc_phy_ops i2c_phy_ops = {
+       .write = microread_i2c_write,
+       .enable = microread_i2c_enable,
+       .disable = microread_i2c_disable,
+};
+
+static int microread_i2c_probe(struct i2c_client *client,
+                              const struct i2c_device_id *id)
+{
+       struct microread_i2c_phy *phy;
+       struct microread_nfc_platform_data *pdata =
+               dev_get_platdata(&client->dev);
+       int r;
+
+       dev_dbg(&client->dev, "client %p", client);
+
+       if (!pdata) {
+               dev_err(&client->dev, "client %p: missing platform data",
+                       client);
+               return -EINVAL;
+       }
+
+       phy = devm_kzalloc(&client->dev, sizeof(struct microread_i2c_phy),
+                          GFP_KERNEL);
+       if (!phy) {
+               dev_err(&client->dev, "Can't allocate microread phy");
+               return -ENOMEM;
+       }
+
+       i2c_set_clientdata(client, phy);
+       phy->i2c_dev = client;
+
+       r = request_threaded_irq(client->irq, NULL, microread_i2c_irq_thread_fn,
+                                IRQF_TRIGGER_RISING | IRQF_ONESHOT,
+                                MICROREAD_I2C_DRIVER_NAME, phy);
+       if (r) {
+               dev_err(&client->dev, "Unable to register IRQ handler");
+               return r;
+       }
+
+       r = microread_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
+                           MICROREAD_I2C_FRAME_HEADROOM,
+                           MICROREAD_I2C_FRAME_TAILROOM,
+                           MICROREAD_I2C_LLC_MAX_PAYLOAD, &phy->hdev);
+       if (r < 0)
+               goto err_irq;
+
+       dev_info(&client->dev, "Probed");
+
+       return 0;
+
+err_irq:
+       free_irq(client->irq, phy);
+
+       return r;
+}
+
+static int microread_i2c_remove(struct i2c_client *client)
+{
+       struct microread_i2c_phy *phy = i2c_get_clientdata(client);
+
+       dev_dbg(&client->dev, "%s\n", __func__);
+
+       microread_remove(phy->hdev);
+
+       free_irq(client->irq, phy);
+
+       return 0;
+}
+
+static struct i2c_device_id microread_i2c_id[] = {
+       { MICROREAD_I2C_DRIVER_NAME, 0},
+       { }
+};
+MODULE_DEVICE_TABLE(i2c, microread_i2c_id);
+
+static struct i2c_driver microread_i2c_driver = {
+       .driver = {
+               .name = MICROREAD_I2C_DRIVER_NAME,
+       },
+       .probe          = microread_i2c_probe,
+       .remove         = microread_i2c_remove,
+       .id_table       = microread_i2c_id,
+};
+
+module_i2c_driver(microread_i2c_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION(DRIVER_DESC);