NFC: microread: Add i2c physical layer

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

3 files changed, 354 insertions, 0 deletions

diff --git a/drivers/nfc/microread/Kconfig b/drivers/nfc/microread/Kconfig
index 5b89d011d098..cd6744bc8db6 100644
--- a/drivers/nfc/microread/Kconfig
+++ b/drivers/nfc/microread/Kconfig
@@ -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.
diff --git a/drivers/nfc/microread/Makefile b/drivers/nfc/microread/Makefile
index 9ce2c53f49a7..74c185165ebf 100644
--- a/drivers/nfc/microread/Makefile
+++ b/drivers/nfc/microread/Makefile
@@ -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
index 000000000000..101089495bf8
--- /dev/null
+++ b/drivers/nfc/microread/i2c.c
@@ -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);