NFC: microread: Add i2c physical layer

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

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.

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

drivers/nfc/microread/i2c.c

+/*
+ * 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);