NFC: Separate pn544 hci driver in HW dependant and independant parts

The driver now has all HCI stuff isolated in one file, and all the
hardware link specifics in another. Writing a pn544 driver on top of
another hardware link is now just a matter of adding a new file for that
new hardware specifics.

Signed-off-by: Eric Lapuyade <eric.lapuyade@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 500 insertions, 0 deletions

diff --git a/drivers/nfc/pn544/i2c.c b/drivers/nfc/pn544/i2c.c
new file mode 100644
index 000000000000..fb430d882352
--- /dev/null
+++ b/drivers/nfc/pn544/i2c.c
@@ -0,0 +1,500 @@
+/*
+ * I2C Link Layer for PN544 HCI based Driver
+ *
+ * Copyright (C) 2012  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/crc-ccitt.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/gpio.h>
+#include <linux/miscdevice.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+
+#include <linux/nfc/pn544.h>
+
+#include <net/nfc/hci.h>
+#include <net/nfc/llc.h>
+
+#include "pn544.h"
+
+#define PN544_I2C_FRAME_HEADROOM 1
+#define PN544_I2C_FRAME_TAILROOM 2
+
+/* framing in HCI mode */
+#define PN544_HCI_I2C_LLC_LEN		1
+#define PN544_HCI_I2C_LLC_CRC		2
+#define PN544_HCI_I2C_LLC_LEN_CRC	(PN544_HCI_I2C_LLC_LEN + \
+					 PN544_HCI_I2C_LLC_CRC)
+#define PN544_HCI_I2C_LLC_MIN_SIZE	(1 + PN544_HCI_I2C_LLC_LEN_CRC)
+#define PN544_HCI_I2C_LLC_MAX_PAYLOAD	29
+#define PN544_HCI_I2C_LLC_MAX_SIZE	(PN544_HCI_I2C_LLC_LEN_CRC + 1 + \
+					 PN544_HCI_I2C_LLC_MAX_PAYLOAD)
+
+static struct i2c_device_id pn544_hci_i2c_id_table[] = {
+	{"pn544", 0},
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, pn544_hci_i2c_id_table);
+
+#define PN544_HCI_I2C_DRIVER_NAME "pn544_hci_i2c"
+
+struct pn544_i2c_phy {
+	struct i2c_client *i2c_dev;
+	struct nfc_hci_dev *hdev;
+
+	unsigned int gpio_en;
+	unsigned int gpio_irq;
+	unsigned int gpio_fw;
+	unsigned int en_polarity;
+
+	int powered;
+
+	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 pn544_hci_i2c_platform_init(struct pn544_i2c_phy *phy)
+{
+	int polarity, retry, ret;
+	char rset_cmd[] = { 0x05, 0xF9, 0x04, 0x00, 0xC3, 0xE5 };
+	int count = sizeof(rset_cmd);
+
+	pr_info(DRIVER_DESC ": %s\n", __func__);
+	dev_info(&phy->i2c_dev->dev, "Detecting nfc_en polarity\n");
+
+	/* Disable fw download */
+	gpio_set_value(phy->gpio_fw, 0);
+
+	for (polarity = 0; polarity < 2; polarity++) {
+		phy->en_polarity = polarity;
+		retry = 3;
+		while (retry--) {
+			/* power off */
+			gpio_set_value(phy->gpio_en, !phy->en_polarity);
+			usleep_range(10000, 15000);
+
+			/* power on */
+			gpio_set_value(phy->gpio_en, phy->en_polarity);
+			usleep_range(10000, 15000);
+
+			/* send reset */
+			dev_dbg(&phy->i2c_dev->dev, "Sending reset cmd\n");
+			ret = i2c_master_send(phy->i2c_dev, rset_cmd, count);
+			if (ret == count) {
+				dev_info(&phy->i2c_dev->dev,
+					 "nfc_en polarity : active %s\n",
+					 (polarity == 0 ? "low" : "high"));
+				goto out;
+			}
+		}
+	}
+
+	dev_err(&phy->i2c_dev->dev,
+		"Could not detect nfc_en polarity, fallback to active high\n");
+
+out:
+	gpio_set_value(phy->gpio_en, !phy->en_polarity);
+}
+
+static int pn544_hci_i2c_enable(void *phy_id)
+{
+	struct pn544_i2c_phy *phy = phy_id;
+
+	pr_info(DRIVER_DESC ": %s\n", __func__);
+
+	gpio_set_value(phy->gpio_fw, 0);
+	gpio_set_value(phy->gpio_en, phy->en_polarity);
+	usleep_range(10000, 15000);
+
+	phy->powered = 1;
+
+	return 0;
+}
+
+static void pn544_hci_i2c_disable(void *phy_id)
+{
+	struct pn544_i2c_phy *phy = phy_id;
+
+	pr_info(DRIVER_DESC ": %s\n", __func__);
+
+	gpio_set_value(phy->gpio_fw, 0);
+	gpio_set_value(phy->gpio_en, !phy->en_polarity);
+	usleep_range(10000, 15000);
+
+	gpio_set_value(phy->gpio_en, phy->en_polarity);
+	usleep_range(10000, 15000);
+
+	gpio_set_value(phy->gpio_en, !phy->en_polarity);
+	usleep_range(10000, 15000);
+
+	phy->powered = 0;
+}
+
+static void pn544_hci_i2c_add_len_crc(struct sk_buff *skb)
+{
+	u16 crc;
+	int len;
+
+	len = skb->len + 2;
+	*skb_push(skb, 1) = len;
+
+	crc = crc_ccitt(0xffff, skb->data, skb->len);
+	crc = ~crc;
+	*skb_put(skb, 1) = crc & 0xff;
+	*skb_put(skb, 1) = crc >> 8;
+}
+
+static void pn544_hci_i2c_remove_len_crc(struct sk_buff *skb)
+{
+	skb_pull(skb, PN544_I2C_FRAME_HEADROOM);
+	skb_trim(skb, PN544_I2C_FRAME_TAILROOM);
+}
+
+/*
+ * Writing a frame must not return the number of written bytes.
+ * It must return either zero for success, or <0 for error.
+ * In addition, it must not alter the skb
+ */
+static int pn544_hci_i2c_write(void *phy_id, struct sk_buff *skb)
+{
+	int r;
+	struct pn544_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);
+
+	pn544_hci_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;
+	}
+
+	pn544_hci_i2c_remove_len_crc(skb);
+
+	return r;
+}
+
+static int check_crc(u8 *buf, int buflen)
+{
+	int len;
+	u16 crc;
+
+	len = buf[0] + 1;
+	crc = crc_ccitt(0xffff, buf, len - 2);
+	crc = ~crc;
+
+	if (buf[len - 2] != (crc & 0xff) || buf[len - 1] != (crc >> 8)) {
+		pr_err(PN544_HCI_I2C_DRIVER_NAME
+		       ": CRC error 0x%x != 0x%x 0x%x\n",
+		       crc, buf[len - 1], buf[len - 2]);
+
+		pr_info(DRIVER_DESC ": %s : BAD CRC\n", __func__);
+		print_hex_dump(KERN_DEBUG, "crc: ", DUMP_PREFIX_NONE,
+			       16, 2, buf, buflen, false);
+		return -EPERM;
+	}
+	return 0;
+}
+
+/*
+ * Reads an shdlc frame and returns it in a newly allocated sk_buff. Guarantees
+ * that i2c bus will be flushed and that next read will start on a new frame.
+ * returned skb contains only LLC header and payload.
+ * returns:
+ * -EREMOTEIO : i2c read error (fatal)
+ * -EBADMSG : frame was incorrect and discarded
+ * -ENOMEM : cannot allocate skb, frame dropped
+ */
+static int pn544_hci_i2c_read(struct pn544_i2c_phy *phy, struct sk_buff **skb)
+{
+	int r;
+	u8 len;
+	u8 tmp[PN544_HCI_I2C_LLC_MAX_SIZE - 1];
+	struct i2c_client *client = phy->i2c_dev;
+
+	r = i2c_master_recv(client, &len, 1);
+	if (r != 1) {
+		dev_err(&client->dev, "cannot read len byte\n");
+		return -EREMOTEIO;
+	}
+
+	if ((len < (PN544_HCI_I2C_LLC_MIN_SIZE - 1)) ||
+	    (len > (PN544_HCI_I2C_LLC_MAX_SIZE - 1))) {
+		dev_err(&client->dev, "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("i2c frame read", *skb);
+
+	r = check_crc((*skb)->data, (*skb)->len);
+	if (r != 0) {
+		kfree_skb(*skb);
+		r = -EBADMSG;
+		goto flush;
+	}
+
+	skb_pull(*skb, 1);
+	skb_trim(*skb, (*skb)->len - 2);
+
+	usleep_range(3000, 6000);
+
+	return 0;
+
+flush:
+	if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0)
+		r = -EREMOTEIO;
+
+	usleep_range(3000, 6000);
+
+	return r;
+}
+
+/*
+ * Reads an shdlc frame from the chip. This is not as straightforward as it
+ * seems. There are cases where we could loose the frame start synchronization.
+ * The frame format is len-data-crc, and corruption can occur anywhere while
+ * transiting on i2c bus, such that we could read an invalid len.
+ * In order to recover synchronization with the next frame, we must be sure
+ * to read the real amount of data without using the len byte. We do this by
+ * assuming the following:
+ * - the chip will always present only one single complete frame on the bus
+ *   before triggering the interrupt
+ * - the chip will not present a new frame until we have completely read
+ *   the previous one (or until we have handled the interrupt).
+ * The tricky case is when we read a corrupted len that is less than the real
+ * len. We must detect this here in order to determine that we need to flush
+ * the bus. This is the reason why we check the crc here.
+ */
+static irqreturn_t pn544_hci_i2c_irq_thread_fn(int irq, void *phy_id)
+{
+	struct pn544_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 = pn544_hci_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 = pn544_hci_i2c_write,
+	.enable = pn544_hci_i2c_enable,
+	.disable = pn544_hci_i2c_disable,
+};
+
+static int __devinit pn544_hci_i2c_probe(struct i2c_client *client,
+				     const struct i2c_device_id *id)
+{
+	struct pn544_i2c_phy *phy;
+	struct pn544_nfc_platform_data *pdata;
+	int r = 0;
+
+	dev_dbg(&client->dev, "%s\n", __func__);
+	dev_dbg(&client->dev, "IRQ: %d\n", client->irq);
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+		dev_err(&client->dev, "Need I2C_FUNC_I2C\n");
+		return -ENODEV;
+	}
+
+	phy = kzalloc(sizeof(struct pn544_i2c_phy), GFP_KERNEL);
+	if (!phy) {
+		dev_err(&client->dev,
+			"Cannot allocate memory for pn544 i2c phy.\n");
+		r = -ENOMEM;
+		goto err_phy_alloc;
+	}
+
+	phy->i2c_dev = client;
+	i2c_set_clientdata(client, phy);
+
+	pdata = client->dev.platform_data;
+	if (pdata == NULL) {
+		dev_err(&client->dev, "No platform data\n");
+		r = -EINVAL;
+		goto err_pdata;
+	}
+
+	if (pdata->request_resources == NULL) {
+		dev_err(&client->dev, "request_resources() missing\n");
+		r = -EINVAL;
+		goto err_pdata;
+	}
+
+	r = pdata->request_resources(client);
+	if (r) {
+		dev_err(&client->dev, "Cannot get platform resources\n");
+		goto err_pdata;
+	}
+
+	phy->gpio_en = pdata->get_gpio(NFC_GPIO_ENABLE);
+	phy->gpio_fw = pdata->get_gpio(NFC_GPIO_FW_RESET);
+	phy->gpio_irq = pdata->get_gpio(NFC_GPIO_IRQ);
+
+	pn544_hci_i2c_platform_init(phy);
+
+	r = request_threaded_irq(client->irq, NULL, pn544_hci_i2c_irq_thread_fn,
+				 IRQF_TRIGGER_RISING | IRQF_ONESHOT,
+				 PN544_HCI_I2C_DRIVER_NAME, phy);
+	if (r < 0) {
+		dev_err(&client->dev, "Unable to register IRQ handler\n");
+		goto err_rti;
+	}
+
+	r = pn544_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
+			    PN544_I2C_FRAME_HEADROOM, PN544_I2C_FRAME_TAILROOM,
+			    PN544_HCI_I2C_LLC_MAX_PAYLOAD, &phy->hdev);
+	if (r < 0)
+		goto err_hci;
+
+	return 0;
+
+err_hci:
+	free_irq(client->irq, phy);
+
+err_rti:
+	if (pdata->free_resources != NULL)
+		pdata->free_resources();
+
+err_pdata:
+	kfree(phy);
+
+err_phy_alloc:
+	return r;
+}
+
+static __devexit int pn544_hci_i2c_remove(struct i2c_client *client)
+{
+	struct pn544_i2c_phy *phy = i2c_get_clientdata(client);
+	struct pn544_nfc_platform_data *pdata = client->dev.platform_data;
+
+	dev_dbg(&client->dev, "%s\n", __func__);
+
+	pn544_hci_remove(phy->hdev);
+
+	if (phy->powered)
+		pn544_hci_i2c_disable(phy);
+
+	free_irq(client->irq, phy);
+	if (pdata->free_resources)
+		pdata->free_resources();
+
+	kfree(phy);
+
+	return 0;
+}
+
+static struct i2c_driver pn544_hci_i2c_driver = {
+	.driver = {
+		   .name = PN544_HCI_I2C_DRIVER_NAME,
+		  },
+	.probe = pn544_hci_i2c_probe,
+	.id_table = pn544_hci_i2c_id_table,
+	.remove = __devexit_p(pn544_hci_i2c_remove),
+};
+
+static int __init pn544_hci_i2c_init(void)
+{
+	int r;
+
+	pr_debug(DRIVER_DESC ": %s\n", __func__);
+
+	r = i2c_add_driver(&pn544_hci_i2c_driver);
+	if (r) {
+		pr_err(PN544_HCI_I2C_DRIVER_NAME
+		       ": driver registration failed\n");
+		return r;
+	}
+
+	return 0;
+}
+
+static void __exit pn544_hci_i2c_exit(void)
+{
+	i2c_del_driver(&pn544_hci_i2c_driver);
+}
+
+module_init(pn544_hci_i2c_init);
+module_exit(pn544_hci_i2c_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION(DRIVER_DESC);