NFC: st21nfcb: Add driver for STMicroelectronics ST21NFCB NFC chip

Add driver for STMicroelectronics ST21NFCB NFC controller.
ST21NFCB is using NCI protocol and a proprietary low level transport
protocol called NDLC used on top.

NDLC:
The protocol defines 2 types of frame:
- One type carrying NCI data (referred as DATAFRAME frames).
- One type carrying protocol information used for flow control and error
control mechanisms (referred as SUPERVISOR frames).

After each frame transmission to the NFC controller, the device host
SHALL waitfor  an ACK (SUPERVISOR frame) reception before sending a
new frame.
The NFC controller MAY send a frame at anytime to the device host.
The NFC controller MAY send a specific WAIT supervisor frame to indicate
to device host that a NCI data packet has been received but that it could
take significant time before the NFC controller sends an ACK and thus
allows next data reception.

Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 462 insertions, 0 deletions

diff --git a/drivers/nfc/st21nfcb/i2c.c b/drivers/nfc/st21nfcb/i2c.c
new file mode 100644
index 000000000000..0f690baaef7a
--- /dev/null
+++ b/drivers/nfc/st21nfcb/i2c.c
@@ -0,0 +1,462 @@
+/*
+ * I2C Link Layer for ST21NFCB NCI based Driver
+ * Copyright (C) 2014  STMicroelectronics SAS. 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/crc-ccitt.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/gpio.h>
+#include <linux/of_irq.h>
+#include <linux/of_gpio.h>
+#include <linux/miscdevice.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/nfc.h>
+#include <linux/firmware.h>
+#include <linux/unaligned/access_ok.h>
+#include <linux/platform_data/st21nfcb.h>
+
+#include <net/nfc/nci.h>
+#include <net/nfc/llc.h>
+#include <net/nfc/nfc.h>
+
+#include "ndlc.h"
+
+#define DRIVER_DESC "NCI NFC driver for ST21NFCB"
+
+/* ndlc header */
+#define ST21NFCB_FRAME_HEADROOM	1
+#define ST21NFCB_FRAME_TAILROOM 0
+
+#define ST21NFCB_NCI_I2C_MIN_SIZE 4   /* PCB(1) + NCI Packet header(3) */
+#define ST21NFCB_NCI_I2C_MAX_SIZE 250 /* req 4.2.1 */
+
+#define ST21NFCB_NCI_I2C_DRIVER_NAME "st21nfcb_nci_i2c"
+
+static struct i2c_device_id st21nfcb_nci_i2c_id_table[] = {
+	{ST21NFCB_NCI_DRIVER_NAME, 0},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, st21nfcb_nci_i2c_id_table);
+
+struct st21nfcb_i2c_phy {
+	struct i2c_client *i2c_dev;
+	struct llt_ndlc *ndlc;
+
+	unsigned int gpio_irq;
+	unsigned int gpio_reset;
+	unsigned int irq_polarity;
+
+	int powered;
+
+	/*
+	 * < 0 if hardware error occured (e.g. i2c err)
+	 * and prevents normal operation.
+	 */
+	int hard_fault;
+};
+
+#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 int st21nfcb_nci_i2c_enable(void *phy_id)
+{
+	struct st21nfcb_i2c_phy *phy = phy_id;
+
+	gpio_set_value(phy->gpio_reset, 0);
+	usleep_range(10000, 15000);
+	gpio_set_value(phy->gpio_reset, 1);
+	phy->powered = 1;
+	usleep_range(80000, 85000);
+
+	return 0;
+}
+
+static void st21nfcb_nci_i2c_disable(void *phy_id)
+{
+	struct st21nfcb_i2c_phy *phy = phy_id;
+
+	pr_info("\n");
+
+	phy->powered = 0;
+	/* reset chip in order to flush clf */
+	gpio_set_value(phy->gpio_reset, 0);
+	usleep_range(10000, 15000);
+	gpio_set_value(phy->gpio_reset, 1);
+}
+
+static void st21nfcb_nci_remove_header(struct sk_buff *skb)
+{
+	skb_pull(skb, ST21NFCB_FRAME_HEADROOM);
+}
+
+/*
+ * 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 st21nfcb_nci_i2c_write(void *phy_id, struct sk_buff *skb)
+{
+	int r = -1;
+	struct st21nfcb_i2c_phy *phy = phy_id;
+	struct i2c_client *client = phy->i2c_dev;
+
+	I2C_DUMP_SKB("st21nfcb_nci_i2c_write", skb);
+
+	if (phy->hard_fault != 0)
+		return phy->hard_fault;
+
+	r = i2c_master_send(client, skb->data, skb->len);
+	if (r == -EREMOTEIO) {  /* Retry, chip was in standby */
+		usleep_range(1000, 4000);
+		r = i2c_master_send(client, skb->data, skb->len);
+	}
+
+	if (r >= 0) {
+		if (r != skb->len)
+			r = -EREMOTEIO;
+		else
+			r = 0;
+	}
+
+	st21nfcb_nci_remove_header(skb);
+
+	return r;
+}
+
+/*
+ * Reads an ndlc frame and returns it in a newly allocated sk_buff.
+ * returns:
+ * frame size : if received frame is complete (find ST21NFCB_SOF_EOF at
+ * end of read)
+ * -EAGAIN : if received frame is incomplete (not find ST21NFCB_SOF_EOF
+ * at end of read)
+ * -EREMOTEIO : i2c read error (fatal)
+ * -EBADMSG : frame was incorrect and discarded
+ * (value returned from st21nfcb_nci_i2c_repack)
+ * -EIO : if no ST21NFCB_SOF_EOF is found after reaching
+ * the read length end sequence
+ */
+static int st21nfcb_nci_i2c_read(struct st21nfcb_i2c_phy *phy,
+				 struct sk_buff **skb)
+{
+	int r;
+	u8 len;
+	u8 buf[ST21NFCB_NCI_I2C_MAX_SIZE];
+	struct i2c_client *client = phy->i2c_dev;
+
+	r = i2c_master_recv(client, buf, 4);
+	if (r == -EREMOTEIO) {  /* Retry, chip was in standby */
+		usleep_range(1000, 4000);
+		r = i2c_master_recv(client, buf, 4);
+	} else if (r != 4) {
+		nfc_err(&client->dev, "cannot read ndlc & nci header\n");
+		return -EREMOTEIO;
+	}
+
+	len = be16_to_cpu(*(__be16 *) (buf + 2));
+	if (len > ST21NFCB_NCI_I2C_MAX_SIZE) {
+		nfc_err(&client->dev, "invalid frame len\n");
+		return -EBADMSG;
+	}
+
+	*skb = alloc_skb(4 + len, GFP_KERNEL);
+	if (*skb == NULL)
+		return -ENOMEM;
+
+	skb_reserve(*skb, 4);
+	skb_put(*skb, 4);
+	memcpy((*skb)->data, buf, 4);
+
+	if (!len)
+		return 0;
+
+	r = i2c_master_recv(client, buf, len);
+	if (r != len) {
+		kfree_skb(*skb);
+		return -EREMOTEIO;
+	}
+
+	skb_put(*skb, len);
+	memcpy((*skb)->data + 4, buf, len);
+
+	I2C_DUMP_SKB("i2c frame read", *skb);
+
+	return 0;
+}
+
+/*
+ * Reads an ndlc frame from the chip.
+ *
+ * On ST21NFCB, IRQ goes in idle state when read starts.
+ */
+static irqreturn_t st21nfcb_nci_irq_thread_fn(int irq, void *phy_id)
+{
+	struct st21nfcb_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)
+		return IRQ_HANDLED;
+
+	if (!phy->powered) {
+		st21nfcb_nci_i2c_disable(phy);
+		return IRQ_HANDLED;
+	}
+
+	r = st21nfcb_nci_i2c_read(phy, &skb);
+	if (r == -EREMOTEIO) {
+		phy->hard_fault = r;
+                ndlc_recv(phy->ndlc, NULL);
+		return IRQ_HANDLED;
+	} else if (r == -ENOMEM || r == -EBADMSG) {
+		return IRQ_HANDLED;
+	}
+
+	ndlc_recv(phy->ndlc, skb);
+
+	return IRQ_HANDLED;
+}
+
+static struct nfc_phy_ops i2c_phy_ops = {
+	.write = st21nfcb_nci_i2c_write,
+	.enable = st21nfcb_nci_i2c_enable,
+	.disable = st21nfcb_nci_i2c_disable,
+};
+
+#ifdef CONFIG_OF
+static int st21nfcb_nci_i2c_of_request_resources(struct i2c_client *client)
+{
+	struct st21nfcb_i2c_phy *phy = i2c_get_clientdata(client);
+	struct device_node *pp;
+	int gpio;
+	int r;
+
+	pp = client->dev.of_node;
+	if (!pp)
+		return -ENODEV;
+
+	/* Get GPIO from device tree */
+	gpio = of_get_named_gpio(pp, "reset-gpios", 0);
+	if (gpio < 0) {
+		nfc_err(&client->dev,
+			"Failed to retrieve reset-gpios from device tree\n");
+		return gpio;
+	}
+
+	/* GPIO request and configuration */
+	r = devm_gpio_request(&client->dev, gpio, "clf_reset");
+	if (r) {
+		nfc_err(&client->dev, "Failed to request reset pin\n");
+		return -ENODEV;
+	}
+
+	r = gpio_direction_output(gpio, 1);
+	if (r) {
+		nfc_err(&client->dev,
+			"Failed to set reset pin direction as output\n");
+		return -ENODEV;
+	}
+	phy->gpio_reset = gpio;
+
+	/* IRQ */
+	r = irq_of_parse_and_map(pp, 0);
+	if (r < 0) {
+		nfc_err(&client->dev,
+				"Unable to get irq, error: %d\n", r);
+		return r;
+	}
+
+	phy->irq_polarity = irq_get_trigger_type(r);
+	client->irq = r;
+
+	return 0;
+}
+#else
+static int st21nfcb_nci_i2c_of_request_resources(struct i2c_client *client)
+{
+	return -ENODEV;
+}
+#endif
+
+static int st21nfcb_nci_i2c_request_resources(struct i2c_client *client)
+{
+	struct st21nfcb_nfc_platform_data *pdata;
+	struct st21nfcb_i2c_phy *phy = i2c_get_clientdata(client);
+	int r;
+	int irq;
+
+	pdata = client->dev.platform_data;
+	if (pdata == NULL) {
+		nfc_err(&client->dev, "No platform data\n");
+		return -EINVAL;
+	}
+
+	/* store for later use */
+	phy->gpio_irq = pdata->gpio_irq;
+	phy->gpio_reset = pdata->gpio_reset;
+	phy->irq_polarity = pdata->irq_polarity;
+
+	r = devm_gpio_request(&client->dev, phy->gpio_irq, "wake_up");
+	if (r) {
+		pr_err("%s : gpio_request failed\n", __FILE__);
+		return -ENODEV;
+	}
+
+	r = gpio_direction_input(phy->gpio_irq);
+	if (r) {
+		pr_err("%s : gpio_direction_input failed\n", __FILE__);
+		return -ENODEV;
+	}
+
+	r = devm_gpio_request(&client->dev,
+			      phy->gpio_reset, "clf_reset");
+	if (r) {
+		pr_err("%s : reset gpio_request failed\n", __FILE__);
+		return -ENODEV;
+	}
+
+	r = gpio_direction_output(phy->gpio_reset, 1);
+	if (r) {
+		pr_err("%s : reset gpio_direction_output failed\n",
+			__FILE__);
+		return -ENODEV;
+	}
+
+	/* IRQ */
+	irq = gpio_to_irq(phy->gpio_irq);
+	if (irq < 0) {
+		nfc_err(&client->dev,
+			"Unable to get irq number for GPIO %d error %d\n",
+			phy->gpio_irq, r);
+		return -ENODEV;
+	}
+	client->irq = irq;
+
+	return 0;
+}
+
+static int st21nfcb_nci_i2c_probe(struct i2c_client *client,
+				  const struct i2c_device_id *id)
+{
+	struct st21nfcb_i2c_phy *phy;
+	struct st21nfcb_nfc_platform_data *pdata;
+	int r;
+
+	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)) {
+		nfc_err(&client->dev, "Need I2C_FUNC_I2C\n");
+		return -ENODEV;
+	}
+
+	phy = devm_kzalloc(&client->dev, sizeof(struct st21nfcb_i2c_phy),
+			   GFP_KERNEL);
+	if (!phy) {
+		nfc_err(&client->dev,
+			"Cannot allocate memory for st21nfcb i2c phy.\n");
+		return -ENOMEM;
+	}
+
+	phy->i2c_dev = client;
+
+	i2c_set_clientdata(client, phy);
+
+	pdata = client->dev.platform_data;
+	if (!pdata && client->dev.of_node) {
+		r = st21nfcb_nci_i2c_of_request_resources(client);
+		if (r) {
+			nfc_err(&client->dev, "No platform data\n");
+			return r;
+		}
+	} else if (pdata) {
+		r = st21nfcb_nci_i2c_request_resources(client);
+		if (r) {
+			nfc_err(&client->dev,
+				"Cannot get platform resources\n");
+			return r;
+		}
+	} else {
+		nfc_err(&client->dev,
+			"st21nfcb platform resources not available\n");
+		return -ENODEV;
+	}
+
+	r = devm_request_threaded_irq(&client->dev, client->irq, NULL,
+				st21nfcb_nci_irq_thread_fn,
+				phy->irq_polarity | IRQF_ONESHOT,
+				ST21NFCB_NCI_DRIVER_NAME, phy);
+	if (r < 0) {
+		nfc_err(&client->dev, "Unable to register IRQ handler\n");
+		return r;
+	}
+
+	return ndlc_probe(phy, &i2c_phy_ops, &client->dev,
+			ST21NFCB_FRAME_HEADROOM, ST21NFCB_FRAME_TAILROOM,
+			&phy->ndlc);
+}
+
+static int st21nfcb_nci_i2c_remove(struct i2c_client *client)
+{
+	struct st21nfcb_i2c_phy *phy = i2c_get_clientdata(client);
+
+	dev_dbg(&client->dev, "%s\n", __func__);
+
+	ndlc_remove(phy->ndlc);
+
+	if (phy->powered)
+		st21nfcb_nci_i2c_disable(phy);
+
+	return 0;
+}
+
+static const struct of_device_id of_st21nfcb_i2c_match[] = {
+	{ .compatible = "st,st21nfcb_i2c", },
+	{}
+};
+
+static struct i2c_driver st21nfcb_nci_i2c_driver = {
+	.driver = {
+		.owner = THIS_MODULE,
+		.name = ST21NFCB_NCI_I2C_DRIVER_NAME,
+		.owner = THIS_MODULE,
+		.of_match_table = of_match_ptr(of_st21nfcb_i2c_match),
+	},
+	.probe = st21nfcb_nci_i2c_probe,
+	.id_table = st21nfcb_nci_i2c_id_table,
+	.remove = st21nfcb_nci_i2c_remove,
+};
+
+module_i2c_driver(st21nfcb_nci_i2c_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION(DRIVER_DESC);