NFC: Add STMicroelectronics ST95HF driver

This driver supports STMicroelectronics NFC Transceiver
"ST95HF", in in initiator role to read/write ISO14443 Type 4A,
ISO14443 Type 4B and ISO15693 Type5 tags.

The ST95HF datasheet is available here:
http://www.st.com/web/en/resource/technical/document/datasheet/DM00102056.pdf

Signed-off-by: Shikha Singh <shikha.singh@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/nfc/Kconfig

@@ -76,4 +76,5 @@ source "drivers/nfc/st21nfca/Kconfig"
 source "drivers/nfc/st-nci/Kconfig"
 source "drivers/nfc/nxp-nci/Kconfig"
 source "drivers/nfc/s3fwrn5/Kconfig"
+source "drivers/nfc/st95hf/Kconfig"
 endmenu

drivers/nfc/Makefile

@@ -16,3 +16,4 @@ obj-$(CONFIG_NFC_ST21NFCA)  	+= st21nfca/
 obj-$(CONFIG_NFC_ST_NCI)	+= st-nci/
 obj-$(CONFIG_NFC_NXP_NCI)	+= nxp-nci/
 obj-$(CONFIG_NFC_S3FWRN5)	+= s3fwrn5/
+obj-$(CONFIG_NFC_ST95HF)	+= st95hf/

drivers/nfc/st95hf/Kconfig

@@ -0,0 +1,10 @@
+config NFC_ST95HF
+	tristate "ST95HF NFC Transceiver driver"
+	depends on SPI && NFC_DIGITAL
+	help
+	This enables the ST NFC driver for ST95HF NFC transceiver.
+	This makes use of SPI framework to communicate with transceiver
+	and registered with NFC digital core to support Linux NFC framework.
+
+	Say Y here to compile support for ST NFC transceiver ST95HF
+	linux driver into the kernel or say M to compile it as module.

drivers/nfc/st95hf/Makefile

@@ -0,0 +1,6 @@
+#
+# Makefile for STMicroelectronics NFC transceiver ST95HF
+#
+
+obj-$(CONFIG_NFC_ST95HF)	+= st95hf.o
+st95hf-objs			:= spi.o core.o

drivers/nfc/st95hf/spi.c

@@ -0,0 +1,167 @@
+/*
+ * ----------------------------------------------------------------------------
+ * drivers/nfc/st95hf/spi.c function definitions for SPI communication
+ * ----------------------------------------------------------------------------
+ * Copyright (C) 2015 STMicroelectronics Pvt. Ltd. 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/>.
+ */
+
+#include "spi.h"
+
+/* Function to send user provided buffer to ST95HF through SPI */
+int st95hf_spi_send(struct st95hf_spi_context *spicontext,
+		    unsigned char *buffertx,
+		    int datalen,
+		    enum req_type reqtype)
+{
+	struct spi_message m;
+	int result = 0;
+	struct spi_device *spidev = spicontext->spidev;
+	struct spi_transfer tx_transfer = {
+		.tx_buf = buffertx,
+		.len = datalen,
+	};
+
+	mutex_lock(&spicontext->spi_lock);
+
+	if (reqtype == SYNC) {
+		spicontext->req_issync = true;
+		reinit_completion(&spicontext->done);
+	} else {
+		spicontext->req_issync = false;
+	}
+
+	spi_message_init(&m);
+	spi_message_add_tail(&tx_transfer, &m);
+
+	result = spi_sync(spidev, &m);
+	if (result) {
+		dev_err(&spidev->dev, "error: sending cmd to st95hf using SPI = %d\n",
+			result);
+		mutex_unlock(&spicontext->spi_lock);
+		return result;
+	}
+
+	/* return for asynchronous or no-wait case */
+	if (reqtype == ASYNC) {
+		mutex_unlock(&spicontext->spi_lock);
+		return 0;
+	}
+
+	result = wait_for_completion_timeout(&spicontext->done,
+					     msecs_to_jiffies(1000));
+	/* check for timeout or success */
+	if (!result) {
+		dev_err(&spidev->dev, "error: response not ready timeout\n");
+		result = -ETIMEDOUT;
+	} else {
+		result = 0;
+	}
+
+	mutex_unlock(&spicontext->spi_lock);
+
+	return result;
+}
+EXPORT_SYMBOL_GPL(st95hf_spi_send);
+
+/* Function to Receive command Response */
+int st95hf_spi_recv_response(struct st95hf_spi_context *spicontext,
+			     unsigned char *receivebuff)
+{
+	int len = 0;
+	struct spi_transfer tx_takedata;
+	struct spi_message m;
+	struct spi_device *spidev = spicontext->spidev;
+	unsigned char readdata_cmd = ST95HF_COMMAND_RECEIVE;
+	struct spi_transfer t[2] = {
+		{.tx_buf = &readdata_cmd, .len = 1,},
+		{.rx_buf = receivebuff, .len = 2, .cs_change = 1,},
+	};
+
+	int ret = 0;
+
+	memset(&tx_takedata, 0x0, sizeof(struct spi_transfer));
+
+	mutex_lock(&spicontext->spi_lock);
+
+	/* First spi transfer to know the length of valid data */
+	spi_message_init(&m);
+	spi_message_add_tail(&t[0], &m);
+	spi_message_add_tail(&t[1], &m);
+
+	ret = spi_sync(spidev, &m);
+	if (ret) {
+		dev_err(&spidev->dev, "spi_recv_resp, data length error = %d\n",
+			ret);
+		mutex_unlock(&spicontext->spi_lock);
+		return ret;
+	}
+
+	/* As 2 bytes are already read */
+	len = 2;
+
+	/* Support of long frame */
+	if (receivebuff[0] & 0x60)
+		len += (((receivebuff[0] & 0x60) >> 5) << 8) | receivebuff[1];
+	else
+		len += receivebuff[1];
+
+	/* Now make a transfer to read only relevant bytes */
+	tx_takedata.rx_buf = &receivebuff[2];
+	tx_takedata.len = len - 2;
+
+	spi_message_init(&m);
+	spi_message_add_tail(&tx_takedata, &m);
+
+	ret = spi_sync(spidev, &m);
+
+	mutex_unlock(&spicontext->spi_lock);
+	if (ret) {
+		dev_err(&spidev->dev, "spi_recv_resp, data read error = %d\n",
+			ret);
+		return ret;
+	}
+
+	return len;
+}
+EXPORT_SYMBOL_GPL(st95hf_spi_recv_response);
+
+int st95hf_spi_recv_echo_res(struct st95hf_spi_context *spicontext,
+			     unsigned char *receivebuff)
+{
+	unsigned char readdata_cmd = ST95HF_COMMAND_RECEIVE;
+	struct spi_transfer t[2] = {
+		{.tx_buf = &readdata_cmd, .len = 1,},
+		{.rx_buf = receivebuff, .len = 1,},
+	};
+	struct spi_message m;
+	struct spi_device *spidev = spicontext->spidev;
+	int ret = 0;
+
+	mutex_lock(&spicontext->spi_lock);
+
+	spi_message_init(&m);
+	spi_message_add_tail(&t[0], &m);
+	spi_message_add_tail(&t[1], &m);
+	ret = spi_sync(spidev, &m);
+
+	mutex_unlock(&spicontext->spi_lock);
+
+	if (ret)
+		dev_err(&spidev->dev, "recv_echo_res, data read error = %d\n",
+			ret);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(st95hf_spi_recv_echo_res);

drivers/nfc/st95hf/spi.h

@@ -0,0 +1,64 @@
+/*
+ * ---------------------------------------------------------------------------
+ * drivers/nfc/st95hf/spi.h functions declarations for SPI communication
+ * ---------------------------------------------------------------------------
+ * Copyright (C) 2015 STMicroelectronics – 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/>.
+ */
+
+#ifndef __LINUX_ST95HF_SPI_H
+#define __LINUX_ST95HF_SPI_H
+
+#include <linux/spi/spi.h>
+
+/* Basic ST95HF SPI CMDs */
+#define ST95HF_COMMAND_SEND	0x0
+#define ST95HF_COMMAND_RESET	0x1
+#define ST95HF_COMMAND_RECEIVE	0x2
+
+#define ST95HF_RESET_CMD_LEN	0x1
+
+/*
+ * structure to contain st95hf spi communication specific information.
+ * @req_issync: true for synchronous calls.
+ * @spidev: st95hf spi device object.
+ * @done: completion structure to wait for st95hf response
+ *	for synchronous calls.
+ * @spi_lock: mutex to allow only one spi transfer at a time.
+ */
+struct st95hf_spi_context {
+	bool req_issync;
+	struct spi_device *spidev;
+	struct completion done;
+	struct mutex spi_lock;
+};
+
+/* flag to differentiate synchronous & asynchronous spi request */
+enum req_type {
+	SYNC,
+	ASYNC,
+};
+
+int st95hf_spi_send(struct st95hf_spi_context *spicontext,
+		    unsigned char *buffertx,
+		    int datalen,
+		    enum req_type reqtype);
+
+int st95hf_spi_recv_response(struct st95hf_spi_context *spicontext,
+			     unsigned char *receivebuff);
+
+int st95hf_spi_recv_echo_res(struct st95hf_spi_context *spicontext,
+			     unsigned char *receivebuff);
+
+#endif